Model Engine Maker
Engines => Your Own Design => Topic started by: Brian Rupnow on May 24, 2018, 01:52:02 AM
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This is an engine which has always interested me. I think I first seen an engine like this posted by Tel from Australia. I was bored today, so I thought I would begin sussing out a design for one, built from bar stock. The one in this post has 1" bore cylinders with a 1.732" stroke. The flywheel is almost 4" in diameter (I am still trying to find a way to use those two steel rings I made up for the Kerzel. They didn't work out on the Kerzel, but they may do fine here.) Stay tuned, and as the design develops I will posted updated models.
(https://imageshack.com/a/img922/1662/QVFSto.jpg)
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Excellent, I love it when you get bored!!
:popcorn: :popcorn: :popcorn:
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Brian,
Chris is right its time for the :popcorn: as your builds are always entertaining.
Art
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Another 4 hours and we go from concept to an animation of the finished engine. I decided that a 4" flywheel was small enough that it looked out of place, so I bumped it up to 6" diameter.
https://www.youtube.com/watch?v=FUln-ar9By4&feature=youtu.be (https://www.youtube.com/watch?v=FUln-ar9By4&feature=youtu.be)
(https://imageshack.com/a/img921/9756/XCXqii.jpg)[/img]
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I think I first seen an engine like this posted by Tel from Australia.
That would be the "Green Twin" from Preston's as it became known. Tel made a start on his and Pat Jorgenson drew it all out in CAD and made some castings for it. I've still got it on my "future projects" list and if I do make it it will be fabricated but made to look like castings.
(https://prestonservices.co.uk/wp-content/uploads/Oscillating_Twin_Horiz_1.jpg)
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Thanks Jason--I spent about 4 hours cruising the internet looking for that one, but all I could find were pictures of "Double Tangye" engines.
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but made to look like castings.
:lolb:
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Thanks Jason--I spent about 4 hours cruising the internet looking for that one, but all I could find were pictures of "Double Tangye" engines.
That's the problem with castings the same old thing crops up again and again, if you want something a bit more original and exclusive you just gota do it yourself.
That little single oscillator I did at Christmas is basically one half you your twin.
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Thanks Jason--I spent about 4 hours cruising the internet looking for that one, but all I could find were pictures of "Double Tangye" engines.
That's the problem with castings the same old thing crops up again and again, if you want something a bit more original and exclusive you just gota do it yourself.
Like a Le Blond 60 engine ::)
Jo
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Le Blonde....
Who mentioned Le Blonde? :Love:
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I like blondes---
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I love mine!!
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Like a Le Blond 60 engine ::)
Jo
It's got the look of the Morton M5 about it or vice versa :)
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Another nice project Brian. I didn't figure it would be long before something caught your eye. Looking forward to it.
Bill
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If I make the spacer transparent, you can see the 1/4" diameter pivot that is attached to the cylinder and passes thru a 1/4" hole in the angle. A stiff little compression spring and a 1/4" nylock nut ensures that the "face" of the cylinder body is held tightly against the face of the angle to avoid pressure loss, but still lets the cylinder pivot.
(https://imageshack.com/a/img921/6813/6KF3t1.jpg)
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The steeper angle of your design reminds me of the old air pumps often seen in labs
(http://www.aquarist-classifieds.co.uk/php/image/68996.jpg)
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Just a thought but would the cranks be better set at 90o to allow self starting ?
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Gas_mantle--I did think of that, but decided for the sake of balance to leave the crank at 180 degrees. If this was going to be a real "working engine" I would make the cylinders from cast iron or bronze, and make the angle from cast iron as well, because of the high wear factor at the point where the cylinder face pivots against the angle. Since it will only ever live as a "demonstration" engine, the cylinders and pistons will still be made from cast iron, but the angle will be 6061 aluminum. The green colored end caps will probably be made from brass for a bit of contrast. The flywheel is massive enough that I am considering making it from solid aluminum.
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It's got the look of the Morton M5 about it or vice versa :)
That's the problem with doing models of real engines the same old thing crops up again and again :facepalm:
Jo
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I've just been publicly whipped by someone on another forum. I had suggested that the engine would run "smoother" with better balance if the crankshaft was set up for 180 degrees. I was wrong. With the crank throws at 180 degrees, you only get a power stroke twice in one full revolution of the crankshaft. With the crankshaft set for 90 degrees, you not only get self starting capability, you also get a power stroke every 90 degrees, so consequently the engine should run much smoother and slower with a 90 degree crank.---Brian
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When I suggested a 90o offset I reasoned it would run smoother but I kinda thought a relatively heavy base would be needed to dampen the uneven cylinder movement.
I can appreciate you are building a twin engine as a fun exercise and to look attractive but personally I'd want a twin to have an advantage over a single (whether that be self starting or smoother running) and to me a 180o twin is really little more than a single :headscratch:
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When I suggested a 90o offset I reasoned it would run smoother but I kinda thought a relatively heavy base would be needed to dampen the uneven cylinder movement.
I can appreciate you are building a twin engine as a fun exercise and to look attractive but personally I'd want a twin to have an advantage over a single (whether that be self starting or smoother running) and to me a 180o twin is really little more than a single :headscratch:
We live---we learn. My first thought was that with a 90 degree crankshaft the engine would tend to "gallop" at low speed. I had that wrong. It might "gallop" if the cylinders were single acting, but with them being double acting, it should run smoother with a 90 degree crank.
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i like your engine but 180 degree or 90 degree is up to you 180 degree will be better balanced at high speed not self starting 90 degree will be self starting and run slower so thats for you to decide.
In full size engines there are both.you decide .its what you like.
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I'll follow along with interest, your threads always generate good talking points and give people chance to exchange ideas :)
Looking back at the photos Jason posted, the green engine appears to have a 90o offset - admittedly the air pumps appear to be 180o but they are being driven from the crank so a balanced oscillation seems to make more sense in that case.
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Locomotives don't gallop...
Pete
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Two cylinders and either 90 or 180 degree crank ….
90 degrees gives a smother torsional running - no matter if single or double acting and that is the reason why several modern two cylinder motorcycle engines are done this way …!... The negative side effect is vibration balancing - first order + rocking couple and this can be cured with a counter rotating balancer axel.
180 degrees has a bad torsional running as both pistons comes to complete standstill at the same time every 180 degrees. First order vibrations are canceled but you still has the rocking couple. A balance axle can cure the rocking couple, but not the torsional unbalance …!
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As you are going to have to have removable cranks so the engine can be assembles it would beeasy to try it with bot 90 and 180 degree settings and see what difference it makes to running.
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It looks like big oscillators for real work are set at 90o
http://www.shippingwondersoftheworld.com/oscillating_engines.html
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Yes Jason--for the sake of one additional keyway in the end of the crankshaft, I am going to make this engine capable of running either/or 90 degrees and 180 degrees.
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This morning I priced out the material to build this engine. It was going to cost $155 for all of the material except the bearings. $50 of that was for brass, so I did a very deep scrounge of every bit of brass and/or bronze I have tucked away. I still had the top knob of that 50 pound bronze government weight that was used to check scales, and one lonesome piece of 2" bronze round stock x about 7/8" long. That actually yielded enough bronze to make four cylinder end caps. I have lots of little pieces to make the piston rod ends from. As soon as I have posted this, I'm heading out to buy the rest of the material.
(https://imageshack.com/a/img923/5083/DcA6B2.jpg)
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I've just been publicly whipped by someone on another forum. I had suggested that the engine would run "smoother" with better balance if the crankshaft was set up for 180 degrees. I was wrong. With the crank throws at 180 degrees, you only get a power stroke twice in one full revolution of the crankshaft. With the crankshaft set for 90 degrees, you not only get self starting capability, you also get a power stroke every 90 degrees, so consequently the engine should run much smoother and slower with a 90 degree crank.---Brian
I was going to say the same then saw this post. Still, will be interesting to see the real difference if you can configure both ways.
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In the picture you see $105 worth of material. $25 for the 2" diameter cast iron and $80 for the aluminum angle and 2" thick bar. I worked for about 3 hours to salvage $50 worth of bronze that I had laying around my shop.--Not very sound economics, but these small engines never make sense from a $$ point of view. I have finished turning the two cylinder end caps for the non rod ends, and I have the material for the other two cylinder caps up in the lathe. That will be tomorrows job.
(https://imageshack.com/a/img922/2748/mtzJum.jpg)
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Brian, why is it costing so much? I reckon I could get enough material for 10 engines for that price over here.
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I pay that much because that is what material costs in Canada. I don't know where you are, but if you can buy the same material cheaper, then I'm happy for you.
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Sorry, It just sounds an awful lot, it’s a shame that.
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Nick: Half the dollar cost to get an idea of the cost in pounds … College metals would charge more than that over here ::)
Jo
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As Jo says 12" of 2" CI bar would be about £25-28 here so actually more than Brian is paying. Those a quiet big lumps of metal in the photo.
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This morning I finished machining the cylinder end caps, except for the counterbored holes for #6 shcs. I managed to break my 1/4" reamer. It started to squeal a bit and then "grabbed" in the bronze and twisted off. That reamer owes me nothing. I've had it for 10 years now, and it has reamed a thousand holes. It was getting dull anyways, and I don't think you can sharpen a reamer without it ending up "undersize". If you wonder why the counterbore in the non rod end caps is so deep, it's because the one piece of bronze I scrounged up had a deep drill hole at that end, and I had to go deep enough to get past the drilled hole. It won't affect the way the engine runs, as it's just a cosmetic feature anyways.
(https://imageshack.com/a/img922/3561/bqEzXe.jpg)
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Fair enough if he bought a foot of each. But you can buy large by the inch here. Those two pieces of aluminium £40? A foot of each I could possibly understand.
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Cylinder end caps are finished, and I'm done for the day. Each end cap has a milled pocket to let air into or out of the cylinder. There will be a few holes in the cylinder body that connect to these pockets, and as the engine oscillates the appropriate holes will be covered and uncovered.
(https://imageshack.com/a/img924/2179/ITxgtZ.jpg)
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Nick--The 2" diameter cast iron was 12" long for $25. Somewhere in that price, there is a cutting charge for the worker to pull a length out of the rack, take it over to the saw, cut off what I need, and then return what is left to the rack. There will be enough in that 12" length to build two or even three engines. If I bought a number of shorter pieces, I would have to pay that cutting charge every time, and the guys I buy it from would hate me. The aluminum angle is 6" x 6" x 1/2" x 16" long, the 6" x 2" aluminum bar is 12" long. The angle and the bar were purchased at a different shop. It made my eyes water a little bit when I paid $80 for the aluminum, but unless I find another supplier right here in my home town, then I pay the price.--And really,--what would you have to pay for the same material?
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It's the same here Brian, as I said about £25-28 for a foot length but if you buy by the inch you are looking at something like £6 and inch :-[
Nick try this e-bay shop and see how the price goes up if you buy the shorter lengths, College that Jo mentioned are about £6.50 an inch too but don't reduce it for longer length so you pay about £80 for a foot :insane:
https://www.ebay.co.uk/itm/50mm-approx-2-dia-meehanite-cast-iron-round-bar-1-12-lengths/263651805198?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D31d599fa697e4da2ae4aa96d840677c1%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D263651805198%26itm%3D263651805198&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A744bd1ab-611a-11e8-997a-74dbd18076f8%7Cparentrq%3A9de914f31630a688a74dd2d7fffd297c%7Ciid%3A1
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This place is about the cheapest I know for aluminium. There may be better deals around in UK locally
www.aluminiumwarehouse.co.uk/6-in-x-6-in-x-1-2-in-aluminum-angle
To the best of my knowledge they will not supply bespoke lengths of angle.
It ain't free by any means.
Brian is quite right to point out the 'hidden' costs. As a percentage they can be very significant.
( Some years ago a shop in Derby was selling transistors in singles actually made a loss on each if you work it out. A 2N2907 was 6p, by the time the assistant had got it, put it in a little bag, taken the cash, possibly given change about 5 mins. had elapsed. At that time the labour rate for a shop assistant was far more than some 72p per hour! )
Dave
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Haven’t checked it all but as Jason says about £25 for a foot of 2” cast iron. Where I go it is sold by the inch at £2.16.
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I have to admit being on vacation and missing a bit. Gas_mantle your link had me chasing down the rabbit hole and finding Fred Dibnah. I was loaned some of his videos some time ago and the boat made me think of him. :ROFL: Won't get me climbing a 150 foot ladder.
Art
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Ah Fred Dibnah, what a great character he was :)
I wonder if he was well known on the other side of the pond ?
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Never hear of him until now but a google search brings up a lot of videos. He does indeed look like an interesting character!!
Bill
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"Come on over baby--A whole lot a hoggin going on---" This morning I am turning my 2" diameter cast iron into rectangular cast iron. For some reason my suppler doesn't stock any cast iron flatbar, so this is what I have to do to get material for my cylinders. Nothing alarmingly difficult, but a lot of cranking. The cylinder bodies are only 2.6" long, but then I need another inch to hold them in the chuck to work on them.
(https://imageshack.com/a/img922/2613/usO6Sf.jpg)
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Never hear of him until now but a google search brings up a lot of videos. He does indeed look like an interesting character!!
Bill
Bill, this is a interesting video of Fred 'laddering' a chimney - it's worth watching carefully to see exactly how he does it :)
https://www.youtube.com/watch?v=F04dGK1_wYA
https://www.youtube.com/watch?v=E-a27xwcLfU
Then when you get to the top it's time to erect the scaffolding ;)
https://www.youtube.com/watch?v=6W_7uIapoHc
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In this shot you can see the two cylinders parted off from the main stock, with one end machined "square" and the finished profile marked out in layout die. The next job will be to set the cylinders up in the four jaw chuck and to drill and ream the bores out to 1" diameter.
(https://imageshack.com/a/img924/3103/0AO9DE.jpg)
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I paid $25 for that length of round cast iron. There has to be at least $5 worth of it in the pile of chips left after boring one cylinder out to 1" diameter. Tomorrow morning when I do the other cylinder, there will be another pile equally big from it.
(https://imageshack.com/a/img923/9379/aljuQ9.jpg)
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Brian, why did you allow the extra 1" length to go in the chuck? You have a very thick cylinder wall so no risk of distortion if held by the outside.
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Jason--It has to do with the profiling on the outside of the cylinder. In order too profile the outside radius, I will mount the cylinder horizontally on a piece of 1" diameter rod held in the chuck on my rotary table and do the profiling in my milling machine. I need a means to attach the 1" rod to the cast iron cylinder, and that is why I left the extra inch of length. I will cross-pin the cylinder to the shaft near the end, then when the profiling is finished, I will remove the cross pin and then cut the cylinder to it's correct length.
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With the price of that material, glueing the cylinder on a mandrel would have saved a third cylinder from the two being made!
Pete
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Pete--I've done it 2 or 3 different ways. I have used Loctite, but then you have a tough time getting rid of the residue when you take things apart. I've done it with expanding mandrels as well, but each time I need an expanding mandrel I have to make it from scratch. This way wastes a bit of material, but it works very well.
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:ThumbsUp: :ThumbsUp: :popcorn: :popcorn:
Love watching you work. I like to kibbitz a bit...
Pete
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Okay--First end of first cylinder tapped and air passage machined. Now it's going to be "repeat 3 more times and pray to the machining Gods that we don't bust a tap." I tried one end cap on just to be really really sure, and everything seems to be fitting okay.
(https://imageshack.com/a/img924/5556/DzEQii.jpg)
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And that, gentlemen, is the way I machine the radius on the outside of the cylinders. You have to look close, but what you see is the cylinder, mounted on a 1" diameter round rod, which is held in the 3 jaw chuck on my rotary table. A half inch end mill is mounted directly over the center of the round bar, and lowered until it is just "kissing" the top of the cylinder, then a little more until it is cutting a full 1/2" wide path but very shallow. Then I take a full length "pass" left to right or vice-versa under the milling cutter. My mill has "stops" on it that I can adjust to limit table travel in the X axis, and I set them so that I don't move the jaws of the chuck under my milling cutter in one direction and just clear of the cylinder in the other direction. My rotary table moves 4 degrees with every full turn of the handle. I advance the rotary table clockwise half a turn, then take a full length pass under the cutting tool. My machine is rigid enough to climb mill, so at the end of one pass I unlock the rotary table, turn the handle half a turn, lock the table and then crank the table in the other direction. After what seems to be about a thousand passes, the cylinder will have turned 90 degrees. Then you crank the rotary table back to its original position and repeat everything, only this time turning the rotary table counterclockwise half a turn between cuts to put the radius on the other side. Don't be confused by the milling vice setting there. It isn't doing anything related to what I'm doing.
(https://imageshack.com/a/img923/4948/Q1SUqJ.jpg)
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So, there we have two cylinders finished. Both of the cast iron cylinders have to spend a bit of time with some 150 grit emery paper to get rid of any unwanted machining marks, but the machining itself is finished. Sixteen #6-32 tapped holes in and no broken tap, big sigh of relief.
(https://imageshack.com/a/img924/5803/qZBwgm.jpg)
(https://imageshack.com/a/img921/5011/GZdTFG.jpg)
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Nice cylinders :ThumbsUp:
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Excellent! :popcorn:
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Very nice Brian. Yeah getting the holes tapped is definitely sigh worthy.
Bill
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This morning I machined the piston rod glands, fitted everything, and made the first assembly of the cylinders. These are "long stroke" cylinders, and Jeez they look huge. 1" bore x 1 3/4" stroke. Those are not the real piston rods you see sticking out the end of the cylinders. They are just some "dummy rods" to aid in keeping everything lined up for assembly. I still have to profile the inward side of the cylinder caps, but had to assemble things to this stage and "mark out" where the fillet ends, as I don't want the fillet to continue around the caps where they meet the cylinder bodies on the lower half.
(https://imageshack.com/a/img921/1772/BiC1OR.jpg)
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This is a big engine. You’ll have to keep your fingers out of the way when you run it!!
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Nick--It is big. I will be running it on low pressure air, but it is big enough to do some real work if I wanted it to.
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Big for sure, should run nice and slow too if you want.
Bill
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Bill--That's why I chose such a long stroke. I think this will be a very low rpm engine with a 1 3/4" stroke length. Those cylinders look huge, yet the model is only 6" long and 8 1/4" tall.
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Another reason to set the cranks at 90 should def allow it to run slower, otherwise that’s one hell of a combined power stroke each half Rev. It will look like a karate punch!
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This morning I'm making piston rod ends. They are not terribly hard to make, but the sequence of machining operations is quite important. In this shot the diameters have been turned onto the end of a stick of 5/8" round bronze. The one closest to the end has been reamed for a 1/4" dia. piston rod. The rod is mostly hidden inside the chuck and hollow headstock shaft. Now I will move operations over to the rotary table on the mill and put the flats on both sides and the 5/16" holes for the crank-pin in. Then back to the lathe where I can part off the one closest to the end.
This morning I'm making piston rod ends. They are not terribly hard to make, but the sequence of machining operations is quite important. In this shot the diameters have been turned onto the end of a stick of 5/8" round bronze. The one closest to the end has been reamed for a 1/4" dia. piston rod. The rod is mostly hidden inside the chuck and hollow headstock shaft. Now I will move operations over to the rotary table on the mill and put the flats on both sides and the 5/16" holes for the crank-pin in. Then back to the lathe where I can part off the one closest to the end.
(https://imageshack.com/a/img924/1786/eyGxTq.jpg)
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Here we have a shot of the two piston rod ends, still attached to the main piece of round bronze they were machined on. It is set up in the rotary table and the two sides have been machined flat. Then the 5/16" holes were drilled and reamed in the same set-up. The part was moved back into the lathe, where the one closest to the end which had already been drilled and reamed to 1/4" was parted off. Then the remaining one was drilled and reamed to 1/4" and then it was parted off. A little rub on my 150 grit emery paper laid out flat on my cast iron band-saw table, and Presto!! We have two more finished parts. I can't remember--I think I can silver solder the bronze ends onto my cold rolled 1/4" piston rods. I may have to do a little test first on a scrap of bronze. I don't want to screw these up. If I have to I can cross-drill and pin them to my piston rods.
(https://imageshack.com/a/img924/1702/sO2oYA.jpg)
(https://imageshack.com/a/img923/5505/MWbMZn.jpg)
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I just realized that I haven't given any real information about the size of this engine. It doesn't occupy a lot of space, and most of it is cylinders and flywheel.
(https://imageshack.com/a/img923/9526/D5GMd6.jpg)
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I did a little test, and yes, it appears that you can indeed silver solder bronze to steel. The solder bonded well to the bronze, but it seems that the heat has caused some alloy in the bronze to "boil up" to the surface and leave a bit of a mess. I think I'm going to play it safe and pin the bronze piston rod ends too the piston rod shafts.
(https://imageshack.com/a/img922/9094/Tfp11i.jpg)
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Whick alloy bronze was it? I've had no trouble with phospher bronze and bearing bronze.
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Whick alloy bronze was it? I've had no trouble with phospher bronze and bearing bronze.
Crueby-I don't really know. I will call my supplier and find out today.
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Hi Brian.
I don't comment much but I love following your work :ThumbsUp:
Cheers
Rich
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Brian, your "silver soldering" never seems to flow so I wonder what you are actually using as the filler material. Could be a high temp one of even brazing rod and that is why you have had to get things hot enough to melt your piece of bronze which was not helped by being thin.
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Thanks Rich---It's good to know someone is watching.---Brian
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This mornings work was to make two cast iron pistons. I had enough short ends of cast iron left over from making cylinders that I was able to find a couple that were "just long enough". I turned both pistons down to about .0005" oversize, then "wrung" them into the cylinders using 600 grit compound. One piston fits really good, one is a little looser than I like, but when I put in a couple of v shaped oil grooves on each piston, that will displace enough material either side of the V to make them fit perfectly, in fact they might have to be "Wrung in" again to get them into the cylinders.
(https://imageshack.com/a/img923/7800/KK0ikg.jpg)
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Dang--Ya gotta love it when a plan comes together---
[(https://imagizer.imageshack.com/v2/659x494q90/r/923/E6QOFA.jpg)
(https://imagizer.imageshack.com/v2/800x507q90/r/921/Zw7rew.jpg)
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Whick alloy bronze was it? I've had no trouble with phospher bronze and bearing bronze.
Crueby-I don't really know. I will call my supplier and find out today.
I never had any trouble with them - am using the 'medium' and 'easy' versions of the silver solder, so the temperature is a little lower than the 'hard', and also like the Tenacity 5 flux (common in UK, available overseas on ebay too) a little better than the Harris white flux, seems to last longer in the molten state before burning off. For the solder, I get the jewelry version of thin wire, easy to cut and fit in to small places, hold with the flux, and when hot it just wicks into the joints.
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One piston fits really good, one is a little looser than I like, but when I put in a couple of v shaped oil grooves on each piston, that will displace enough material either side of the V to make them fit perfectly, in fact they might have to be "Wrung in" again to get them into the cylinders.
I was wrong about that. Putting the v-grooves in the cast iron pistons didn't raise a "berm" of displaced material on each side of the v-groove like it does when working with cold rolled steel. On the cast iron the v is cleanly cut but no metal seems to get displaced on each side.--I live---I learn.
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I decided not to solder the piston rod ends in place on the rods. The holes in the piston rod ends were reamed and provided a good "fit" for the rod end itself, so I used some 638 Loctite and when it had set up I cross drilled with a 1/16" drill and loctited in a 1/16" mild steel pin. A great tip here that was given to me by someone else--It is difficult to buy 1/16" diameter cold rolled steel rod, but the welding supply store sells 1/16" diameter steel welding rod that seems to be perfect for jobs like this and also on pinned crankshafts.
(https://imageshack.com/a/img923/2471/VOSy1o.jpg)
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One piston fits really good, one is a little looser than I like, but when I put in a couple of v shaped oil grooves on each piston, that will displace enough material either side of the V to make them fit perfectly, in fact they might have to be "Wrung in" again to get them into the cylinders.
I was wrong about that. Putting the v-grooves in the cast iron pistons didn't raise a "berm" of displaced material on each side of the v-groove like it does when working with cold rolled steel. On the cast iron the v is cleanly cut but no metal seems to get displaced on each side.--I live---I learn.
Heat the Cast Iron up then cool it quickly: it should grow a few thou ;)
Jo
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Jo--Orange hot and then into a bucket of water?
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Why not just cut a groove then add graphite string covered in oil as a piston ring.
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Gas_Mantle--I've never done that before. All I have ever used is either a Viton o-ring, or no ring at all. I'm waiting to hear back from Jo on her method of "growing " the cast iron a little bit.
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Heating cast Iron does make it " grow " a little but I'd be suggesting natural cooling rather than a quench.
You might end up with a piston that's grown too big to fit and too hard to alter. It's the same as " chilled " castings that are almost un machinable.
Peter, " old school " rules!! ;)
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Peter, " old school " rules!! ;)
The old ways are the best ;)
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Some people use ptfe rings these days but it’s difficult to machine I’ve heard
as not very structurally stable. I recently used some graphited yarn on my regulator gland but it leaked under hydraulic test so platted some ptfe tape and packed that in which did the job. Maybe I didn’t have enough yarn in there.
Regarding growing the cast iron, doesn’t look like it needs it to me looking at the fit you have. Steam engines are very forgiving on the fit, if you want it to run slowly it will be better with a loose sliding fit.
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Okay Jo, let's hear about it. Were you telling me something about cast iron growing when heated that is a true fact, or were you deliberately suggesting something you knew would cause problems. You are saying to "Cool it quickly", somebody else is saying "Don't water quench it or it may yield unmachinable hard spots in the iron. I have Googled this "Cast iron growing" under the effect of heat and I get a lot of conflicting answers. Please give me a little more information on this phenomenon.---Brian
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Hi Brian, I have grown a piston that was not as snug as I wanted by applying heat :).
There is a lot different between cooling a molten piece of iron and a red hot piece. Start by just heating it and letting it cool - measure before and after it might be enough.
Jo
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Hold it at cherry red for a few minutes and then quench in oil
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As it happens, I have a couple of "extra" cast iron pistons that were originally used in my build of a flamesucker engine built to Jan Ridders plans, before I changed to graphite pistons. I will measure the diameter on one before and after heating/cooling and let you know what happened.
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As it happens, I have a couple of "extra" cast iron pistons that were originally used in my build of a flamesucker engine built to Jan Ridders plans, before I changed to graphite pistons. I will measure the diameter on one before and after heating/cooling and let you know what happened.
Very interesting experiment - never knew the size would change at all like that. Too bad you can't keep repeating to grow a much larger chunk!
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I haven't personally heard of this "growing" cast iron by heating, then cooling. However--there are a lot of things that I haven't heard of. This process does seem to have a bit of credibility, but nobody seems really sure about it. Good time for a test. I have two or three model size (3/4" diameter to 1" diameter) cast iron pistons that will never get used but I couldn't bring myself to throw out. Tomorrow we test!!
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Thanks for running a test Brian. Looking forward to seeing the results as well.
Bill
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Well if you don't think our answers are creditable have a look at Ramon's post with photos to prove it.
http://www.modelenginemaker.com/index.php/topic,1334.msg29324.html#msg29324
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............. but nobody seems really sure about it..............
Thanks Jason for pointing Brian in my direction :ThumbsUp:
Yes Brian, I have described on here on more than one occasion about growing pistons that are undersized. It is an easy procedure to carry out but - it does not always work and it can only be done the once - i.e. once 'grown' it can't be reheated to grow more.
A good 'bright red' but not 'orange' is required and a good soak to get the temperature right through the part. If the heat is too high carbon forms on the surface and is quickly removed in lapping with nothing left to work with. If a piston is thin walled then uneven heating and even more important uneven quenching (in oil not water) will lead to distortion possibly, indeed probably, to the detriment of any ability to reclaim it by lapping.
Though I have, over many years, carried this technique out and usually, though not always, with a successful outcome it is not my idea.
Fair credit is due to one 'George Aldrich' whose writings on small engines set the benchmark for many to follow. I read of this technique in one of his monthly columns in Model Aviation or Model Airplane News far too long ago to remember. George was highly respected in the field of small I/C engines - tuning many world classing winning examples. His openness to share his 'secrets' on the techniques involved is not something in my book that should go unrecognised. He did actually write a very good article for the British 'Aeromodeller Annual' called just that - "There Are No Secrets" - a classic piece of work. Credit then where credit is due :)
Hope your testing leads to the same success as I have had
Regards - Tug
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Okay--Here we have two rather dirty cast iron pistons that were made and only used for about half an hour. They have never had any kind of heat treat from me. One will be heated to "orange" and then dropped into a container of oil. The other will be heated to orange and left to air cool back to ambient temperature. I have measured multiple positions around the diameter on both pistons and they are all 0.875" +/- .0005" diameter.
(https://imageshack.com/a/img922/5807/Gai9a8.jpg)
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The results are in. The piston which was heated to bright orange and then allowed to air dry did not change in any way. The heating and air cooling had no effect whatsoever.---BUT---The piston that was heated to bright orange and then tipped into a can of oil has grown, and uniformly measures 0.876" , measured at multiple spots around the piston. So, yes, about 0.001" of growth on the 0.875" diameter. I will set the "grown' piston up in my lathe and turn some off the diameter to see if the machineability has been altered by this test.
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The third test has just been completed. I burned up two drill bits trying to enlarge the center hole in that "grown" piston, to mount it on an arbor. So--not only does the heat and quench make the piston marginally larger, it makes it harder than the devil's horn. Test is over. I conclude that "growing" a cast iron piston is possible, but not advisable because the iron becomes super hard and can no longer be machined with conventional tooling.---Brian
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Well Brian - water and horses spring to mind :D but at least for you you've satisfied yourself that it does work albeit somewhat 'overdone'.
Good luck with the rest of your build :ThumbsUp:
Tug
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Thanks Raymon--It was an interesting little side trip to take. In Jo's first post where she suggested this and used an emoticon with a wink, I figured there had to be a little more to it. There are a number of little "tricks" like that procedure, which work sometimes but not all the times, and if they do work they throw up other different problems. As last resorts in a desperate situation, they can be tried, knowing that if they do you're golden.---If they don't, you were going to have to make a new part anyways. I try to stay away from procedures with unpredictable results, because they're---ahh---Unpredictable.
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No probs Brian :) As you say there are many little tricks and tips that can get you by at times and this is without doubt one of them.
I should have mentioned the hardening - I'm sure I have before but of course heat treating anything with carbon in is going to do so.
Maybe, if there's any general interest I'd be happy to pop up a new post describing the procedure in slightly more depth as it is a 'trick' worth knowing.
Regards - Tug
PS BTW definitely no Y in Ramon ;) nor a D either ;D
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Maybe, if there's any general interest I'd be happy to pop up a new post describing the procedure in slightly more depth as it is a 'trick' worth knowing.
Hi Tug without a Y or a D either ;)
If you did want to describe the procedure in more detail elsewhere I'd be interested to read it.
I work with cast iron in small pieces quite a bit so it could be something useful to know
Thanks :)
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I've been faffing about all weekend trying to convince myself to make both of the crank arms out of steel. Not difficult, just an awful lot of offset turning in the 4 jaw chuck. I chased my tail round and round and finally decided to make them a three part assembly. Probably use aluminum for the slime green hub and brass for the arm itself, with three #4 shcs holding everything together and a steel shaft press fitted into place..(https://imageshack.com/a/img924/5829/izdKGx.jpg)
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Following along.
I thought the discussion on 'growing' cast iron was very interesting.
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Carl--Since getting involved in machining ten years ago, I have found there are two totally different sets of "The way things are." There are a lot of "If we do this, we know that is going to happen."--and we know that sequence is utterly infallible. A + B +C invariably yields D. If it doesn't yield D, then somebody has screwed up!! Those are the rules that professional and hobby machinists go by, because it is "safe". However, there are a complete other set of rules, which sort of sum up as A +B+C might equal D--or---maybe something else. Growing cast iron comes under the second set of realities. We all try some of these different reality "things" to see if they work or not. Sometimes they don't.--or--Sometimes they do, but not all the time.--Interesting stuff indeed.
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I've been the type of person who likes predictability. You do this...you get that. No surprises.
I typically avoid a gray world. But...I've found that often times, what appears to be 'iffy' is simply because a set of 'rules' hasn't been established yet.
It's well worth exploring the gray world.
Mainly because it's there where you get surprises and learnings.
As you said..."Interesting stuff indeed".
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If you make that crank from a rectangular block there would not be much material to remove so won't take long. Could even be done all on the mill as I know you shy away from the 4-jaw. Just drill & ream the holes, taper the two edges and then hold in a vice on the rotary table to do the round bit, press/loctite in a drill rod pin.
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Peter - I have twice tried this morning to begin a separate thread on the matter of 'growing'. Doing the text in Word first it keeps getting locked for editing and I can't get it back. I need to get this (PC) sorted again so back with it later I guess.
Apologies for interrupting your thread Brian
Tug
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Peter - I have twice tried this morning to begin a separate thread on the matter of 'growing'. Doing the text in Word first it keeps getting locked for editing and I can't get it back. I need to get this (PC) sorted again so back with it later I guess.
Apologies for interrupting your thread Brian
Tug
That's ok, there's no rush. I just thought if you are able to explain your method a bit more I'd be interested to read and I'm sure many others would too :)
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After a "machining free" weekend I decided to build some crank arms. I could have used the four jaw chuck in my lathe and turned them from solid (not including the rod journal) or I could make them from built up pieces. I decided to make them "built up" assemblies. Honestly, I think it would have taken about the same amount of time either way. I've been dragging my feet a little on the cylinder assemblies because I need a couple of rather "special" set-ups" involving my rotary table and mill to put a partial radius on the center side of the cylinder caps. Will probably get to that tomorrow.
(https://imageshack.com/a/img922/9213/lNa54o.jpg)
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Looks good Brian.
John
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Nice Brian. Good and solid looking.
Bill
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Maybe a little too solid Bill. I pulled them into the main assembly on CAD and only then realized that the aluminum portion was 1/4" too long. Oh well---Better too long than too short. It'l be an easy fix.
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What a monster!!! With the cylinders and crank arms finished, there isn't much to do now except the angle frame and the flywheel. There are very few "small bits" on this engine anywhere.
(https://imageshack.com/a/img924/7669/L1ifPy.jpg)
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Quite a beast for sure Brian. Should have some decent power, if you want to drive anything with it. The sub assembly looks great !!
Bill
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I suppose it comes down to what you call a "monster" having made quite a few engines now with a very similar 24mm bore I regard them all as quite small engines.
The heavily built design of this one adds a lot to the look of something large and heavy, for example the traditional steam engine would not have solid cylinders they would be a lot thinner waisted with a flange at the ends and the cylinder covers would only be say 3/32" think not 1/4plus as this design. Just look at that green one I posted on page one, you would not think it has a 12" flywheel.
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Here is a rather interesting video showing how I take any "sticky spots" out of an assembled cylinder and piston assembly. No lapping compound is being used, just 30 weight motor oil.
https://www.youtube.com/watch?v=YFalHshAOQ0
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Remember that piece of 2" aluminum plate from way back at the beginning of this thread? Today it's slowly becoming a 1.6" thick flywheel. The key word here is SLOWLY. There's a lot of turning in that 6" dia. flywheel.
(https://imageshack.com/a/img923/483/Nag5T2.jpg)
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Taking shape though, even if slowly. Nice!!
Bill
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Brian.,
I just thought I'd jump in here to let you know I'm following along even if I'm not chiming in every step along the way. Your builds are always fun to follow.
Art
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A slight change to the game plan this morning. I didn't like the flywheel being so far up in the air, and I really didn't like having to work with the frame angles when everything was going to be at such strange angles to machine them. So--this morning I spent a couple of hours bringing the frame around to a more conventional setting. Nothing is lost, but it should be a bit more stable when running, and a lot more easy to machine the frame.
(https://imageshack.com/a/img923/7945/NUPedu.jpg)
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Here we have a rather nasty "in process" shot of the 7/8" holes being drilled around the flywheel, and a family shot of all the completed pieces. That flywheels borders on the ridiculous, but it's what I wanted. I have to figure out a way to deburr the 7/8" holes, and then it's time to move into working on the angle frame.
(https://imageshack.com/a/img921/5342/Meus5c.jpg)
(https://imageshack.com/a/img921/4363/WzUNyo.jpg)
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Just a thought Brian are the cylinder ports a bit on the large size ?
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Would a large port be detrimental to performance? Wouldn’t have thought so, but the cylinders are big for an oscillator so look about right I think. Brian, do you have one of those hand de-burrers with replaceable tips? They are great for holes like this.
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Looks like there might be room for a 1" countersink without hitting the rim or hub if you have one. Just a thought.
Bill
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Would a large port be detrimental to performance? Wouldn’t have thought so, but the cylinders are big for an oscillator so look about right I think. Brian, do you have one of those hand de-burrers with replaceable tips? They are great for holes like this.
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Hi Nick, I'm sure Brian has got everything sussed out and that the engine will run well but I'm just kinda comparing it with the oscillators I have built. The last one I made had about a 25mm bore 40mm stroke but the ports were a lot smaller and it runs very well.
Presumably larger ports require greater angular movement of the cylinder to work properly ?
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Those ports are "best guess". Almost everything I've ever built is set up with 1/8" diameter ports. Since these cylinders have a longer than ordinary stroke, I upped the port size to 0.157" wide. This engine is going to run on compressed air, so port size isn't really a big deal.
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The ultimate evil deburring tool. Some strange tapered thing I inherited from my father, held in a keyless chuck that I repurposed from an old 3/8" drill.
(https://imageshack.com/a/img924/6617/QcaUKJ.jpg)
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By redesigning the frame, it not only simplifies the construction of the frame pieces, it also gives me a nice vertical surface on which to mount the intake/exhaust manifold.
(https://imageshack.com/a/img923/4702/xjOxqp.jpg)
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The deburring tool worked perfectly, and I like re redesign of the frame!!
Bill
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Getting closer to the "green twin" with every iteration. Looks nice.
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Hi Woodguy--I haven't heard from you before. Thanks for stopping by and saying Hi. This is an exciting build for me. I knew when I started designing this that the frame would probably change before I actually got to building it. I like the new frame better, and it is simpler to build.---Brian
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Would a large port be detrimental to performance? Wouldn’t have thought so, but the cylinders are big for an oscillator so look about right I think. Brian, do you have one of those hand de-burrers with replaceable tips? They are great for holes like this.
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Hi Nick, I'm sure Brian has got everything sussed out and that the engine will run well but I'm just kinda comparing it with the oscillators I have built. The last one I made had about a 25mm bore 40mm stroke but the ports were a lot smaller and it runs very well.
Presumably larger ports require greater angular movement of the cylinder to work properly ?
Yes I there is that , you’d need enough angular movement so that the ports were a port width apart. And I suppose excess angular movement could be seen as wasted energy, guess that all depends on the length of the piston rod Brian has chosen.
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Brians long port face allows for more movement as he has the ports quite a distance from the pivot. Down side to this is the increased contact area of the port face creating greater friction. The round face like the green (and grey) twin have less friction but ports are closer to the pivot which is why they are oval shaped and not just simple holes as this keeps the angular movement needed low yet gives a decent area of port.
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I'd be curious to now what the formula is for working out optimum port size on steam engines is. Presumably designers of full size working engines have some mathematical way of finding the optimum.
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Brians long port face allows for more movement as he has the ports quite a distance from the pivot. Down side to this is the increased contact area of the port face creating greater friction. The round face like the green (and grey) twin have less friction but ports are closer to the pivot which is why they are oval shaped and not just simple holes as this keeps the angular movement needed low yet gives a decent area of port.
Can see your point but in theory the friction shouldn’t be any greater as long as the surfaces are lapped (F=uR). More difficult to get a good seal being a larger surface to get flat though, I always put a relief on either the cylinder or mating port face where the pivot is.
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I'd be curious to now what the formula is for working out optimum port size on steam engines is. Presumably designers of full size working engines have some mathematical way of finding the optimum.
They must do but bet it is far from simple - fluid dynamics and all of that! There might be some rough rules of thumb though. As others said, it probably doesn’t matter too much with air sol long as it isn’t so small it’s restrictive. With steam it will be a whole different kettle of fish for power, efficiency, correct blast up chimney to draw fire etc. Wish I knew all of that stuff too!
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After what seemed to be an amazing amount of band sawing and milling, the 6 x 6 x 1/2" aluminum angle has been reduced to two angles 4 1/2" x 2.4" x 1/2" x 7 3/4" long. They are as identical as I can make them, and anything done next is going to make them right and left hand. I am off to a party this afternoon for my old electrical engineer friend who turns 60 years old today. He has been working in Germany for the last 15 years, and just returned to Canada last week. I haven't been to a party in years so I'm looking forward to this.
(https://imageshack.com/a/img924/6066/v9fSaM.jpg)
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Enjoy the welcome party for your friend Brian. Fifteen years is a long time!!
Bill
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Good wife and I drove down to the "big smoke" (Toronto), partied like it was 1999, and got back to Barrie like good old geezers before dark. Great time was had by all, my electrical engineer friend plans on returning to Germany for six more years. You can retire with a pension at sixty six in Germany. Then he is coming back to Canada for his retirement.
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One more pretty picture before I go to bed. By putting a .045 deep counterbore at each port opening and a #10-24 threaded hole between them, I can bolt on my valve block with internal porting and set rubber O-rings in the counterbores to seal everything up. There may even be a possibility of building a reverse into the valve block, but my mind hasn't got that far yet.--- I plan on dowelling everything to maintain the relation ship between all the components of the frame.
(https://imageshack.com/a/img922/1279/HR9QGn.jpg)
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Sometimes you've just got to make big holes!! The largest hole here is 1.7" diameter. the smaller hole that breaks thru the end of the angle is 1 1/2" diameter. These were both done with the boring head in my milling machine. The biggest hole with metal all around it was pretty straightforward. The smaller hole that breaks thru the end of the angle was somewhat "clenchworthy". I drilled and bored both angles together, to ensure that all of the holes lined up. Anything that has a counterbore was drilled first with a clearance drill thru both angles, then counterbored on the near side only. I will have to separate the angles and flip the bottom one over to put the counterbores in the far side.
(https://imageshack.com/a/img924/4952/xwgHUm.jpg)
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The votes aren't all in yet, but Dang, it sure looks promising!!!
(https://imageshack.com/a/img924/260/lcs346.jpg)
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The manifold is really quite simple, with an air inlet only. The only magic (which you can't see, but trust me) is that by taking out the two #10 shcs and flipping the manifold end for end I can reverse the rotation of the engine. In it's current configuration, the exhaust comes out the underside of the manifold. If I flip it over, the exhaust will come out the top side.
(https://imageshack.com/a/img921/9093/pyWGV1.jpg)
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Taking shape nicely :)
It looks to be quite a chunky solidly built engine, just as a matter of interest do you know what the completed model will weigh ?
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I like the inlet exhaust arrangement idea. Is there anyway that could be pivoted centrally to reverse the engine without undoing the bolts and flipping? Maybe not worth the effort!
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I like the inlet exhaust arrangement idea. Is there anyway that could be pivoted centrally to reverse the engine without undoing the bolts and flipping? Maybe not worth the effort!
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Yes there is but I want to get it running before I spend a lot of time on a reversing manifold. The engine weighs about 10 pounds.
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Preliminary results are in from the first assembly and they are good. Everything goes round and round and up and down with no interference issues. The crankshaft is cut to length and keyways are cut and installed. I still have to finish that spreader angle with the blue layout dye on it, but so far things are great. I may even run an airline in and see what results I get. I haven't yet installed the proper pivots nor hold down springs for the cylinders, but I can hold them in by hand for a short test.
(https://imageshack.com/a/img924/3509/6jnZTp.jpg)
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EXCITEMENT rules the day.--It runs!! Not good enough for a video, and you need more arms than an octopus to hold the airgun and the frame and the cylinder, but it runs. Time to run up to Tim Hortons donut shop and have a coffee and an apple fritter to celebrate.
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Hi Brian,
Always enjoy following your builds. You and Jason B. seem to be able to take a project from concept to a running engine in no time at all. Thanks for sharing your designs and knowledge. Always look forward to what you will come up with next.
My wife and I grew up in Western NY State outside of Buffalo. I could see Fort Erie from my living room window across the Niagara River in one place I lived. One of the things I miss most is Tim Hortons. Being so close to Canada and having Tim Horton play for our Buffalo Sabres, our area had Tim Horton donut shops from near the beginning of the franchise I would guess. Every time we go back to visit our family we bring back as many Tim Horton coffee beans as we can fit in our suitcases. Some of the best coffee around.
Kind regards,
Mike
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:whoohoo:
You'll get the :pinkelephant: upon receipt of video. ;D
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Mmmm....apple fritters and coffee. And a successful engine build. You must be livin' right Brian! ;D
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Pic looks great, looking forward to the rest of the bits being on so you can do the video!
Hmmm, no eating-donut-and-smiling icon, this will have to do... :DrinkPint:
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Pic looks great, looking forward to the rest of the bits being on so you can do the video!
Hmmm, no eating-donut-and-smiling icon, this will have to do... :DrinkPint:
(https://www.cheesebuerger.de/images/smilie/nahrung/c035.gif)
Jo
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Once I get this all buttoned up you will never get to see this. So--This is the compression spring and nylock nut that pull the flat base on the cylinder tight up against the side of the angle frame to minimize any air leaks. I don't have a lot of room between the angles when fully assembled, but there should be about 0.030" clearance between the two nylock nuts.
(https://imageshack.com/a/img923/2158/EjrXuO.jpg)
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Everything is back together. It is stiff, but I expected it to be. My butt is kicked for today, but tomorrow I hope to make the manifold and maybe get some air on it. A 1" diameter cylinder at 50 psi will give a force of 40 pounds, and this has two cylinders, so I expect any stiffness will give up fairly quickly with a total of 80 pounds of force acting on the crank arms.
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-Probably Belleville washers would work fine instead of springs. I never even thought of anything but "compression spring". There is a rather delicate balance here, of having the springs exert enough force that all the air doesn't escape between the cylinder and the frame, and yet not so much force that the engine is too stiff to run. Since it is a brand new engine, I don't know if the stiffness in it comes as a result of spring compression too tight, or just accumulated tolerances on everything. Once I get it up and running, I will decide if I have to take a coil or two off the springs.---Brian
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Really looking good, Brian! This one's going to have some power.
If the mating surfaces are really good, the seal will be improved and the friction less if you put a little grease on them. I put a little dab of wheel bearing grease on my oscillator and it made a big difference.
Pete
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Way ahead of you on that Pete. On a brand new engine like this everything is soaked in 30 weight oil for break in. Once it runs a little easier I have some "extra hard usage" heavy truck grease for that area.--Brian
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:ThumbsUp: :ThumbsUp:
Pete
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Things are looking great Brian. Will be looking forward to the video as well once you get things all buttoned up to your liking.
Bill
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I have a couple of small single cylinder "wobblers" from early days ten years ago when I started machining. Brass 1/2" bore cylinders and aluminum frames. Never had a problem with them and was tickled pink when they actually ran. Fast forward ten years, and I have built what is a monster double wobbler compared to those early engines. If I have trouble with "galling" of the aluminum under the 1" bore cylinders, I may have to mill away 1/8" of aluminum and J.B. Weld a piece of cast iron or 660 bronze in the area where the cylinders pivot. Someone had suggested that earlier, but I decided to wait and see whether I would need to do it.---Brian
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A thin bit of UHMW or teflon or such as a 'gasket' will solve the metal-to-metal issues...
Or even greased paper...
Pete
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Why do you need to run it on 50psi if its just a display engine, 5psi should be more than enough. With this lower running pressure you also lower the force required to hold the cylinder against the port face by 90% so can run much lighter springs which will help to reduce the tightness and galling.
Also make a spring seat to go under the locknut or even machine the bottom of the locknut so the spring is centralised rather than being pushed off to one side as it is now. Being crooked will be putting uneven load onto the pivot again making things tighter than they should be.
Address the causes rather than try to fix the symptoms!
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I think you’ll probably find that the spring pulling the faces together hardly contributes to the overall friction in the system. If properly lapped and oiled the friction is very low from that interface. I don’t like aluminium as a material choice for cylinders, especially if it’s a soft grade, but as you say the amount it’s actually going to run it probably doesn’t matter. I’m with Jason, 5psi should be sufficient here. I’ve made a couple of oscillators and rocking engine that will run on lung power, I try to reduce the stiffness by getting fits right during the machining phase.
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You misunderstood me guys. I hope to have it run on 5 or 10 psi. The 50 pound pressure I quoted was just a run in pressure to get it started and take out any tight spots.
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So folks, here we have it. It runs just as well as I had hoped it would, and will self start with the crank throws at 90 degrees to each other. It runs on about 10 psi of air. This engine has the fewest parts of any engine I have ever built. If anyone would like to build this engine, I sell a complete set of plans for $25 Canadian funds. There are 23 drawings in the set, including general arrangements and bills of material. You can contact me at brupnow@rogers.com
https://www.youtube.com/watch?v=AllNZnfLpZc
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:pinkelephant: :pinkelephant:
That runs beautifully, Brian!! Congratulations on another successful engine.
:cheers:
Pete
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Wow - very nice for a first run! Already pretty slow for an oscillator, majestic at that size.
:ThumbsUp:
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After 3/4 of an hour running, 80% of the stiffness is gone. Any residual friction is easily overcome by the power of the engine. I thought it would be like that, but I'm never sure until I've run a new engine for a while.
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Nice work Brian, sounds good too
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Well done Brian. A nice slow runner too. Looks and sounds great.
Bill
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And here's your :pinkelephant:.
:ThumbsUp:
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Great job Brian. It really has an “industrial” look. Think it would be just right what for hooking up to your cross cut saw
Cletus
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Thank you for your kind words gentlemen. This engine has a fit of flair to the style, to me it looks a bit like 1950's version of what engines would be in the future. i.e. "The Jetsons". I didn't make any allowances for a power take-off on this engine because I was only interested in the engine itself. It is easy to see why this type of engine was so popular for small marine applications, there are really no "small or intricate" parts to it.
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Runs great - enjoyed your build log !
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Brian,
It runs great, Good job. I have to admit watching your video had me doing down the Jay Leno rabbit hole.
Art
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As promised, here is the final video of the double cylinder oscillating engine. Please note that I misspoke in the voice-over and said it has a 2 3/4" stroke. That was wrong.--It has a 1 3/4" stroke.---Brian
https://www.youtube.com/watch?v=1id_-5Ahbo4
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Is there a "tried and true" method of making a simple air reversing valve. On my current engine I have two "out" ports which the exhaust comes out of, and two "in" ports where the air pressure goes in. My intake manifold feeds air to the top two ports and allows the bottom two ports to exhaust to atmosphere. I was laying in bed last night thinking about a "reversing handle" on the manifold which would allow me to reverse the engine direction. I have it designed in my head, but it is a bit crude. If a current design exists for this, I would happily copy it.
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Very smooth runner and nice and slow Brian very nice engine indeed. Are the port caves running together both ally. I have some drawings of a reversing valves for engines that I’ve made if you want i can mail them
Stew
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Stew--I would appreciate that.--Brian If you send the plan snail mail, my address is 1095 Carson Road, springwater, Ontario L9X0V4
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Very smooth runner and nice and slow Brian very nice engine indeed. Are the port caves running together both ally. I have some drawings of a reversing valves for engines that I’ve made if you want i can mail them
Stew
Stew--Not sure what you mean by "port caves". The frame is aluminum and has port passsages drilled in it. The rocking cylinders are cast iron and have the mating ports drilled in them, in typical wobbler fashion.---Brian
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Now we're going to engage in a little foolery here. The part shown is part #1 of a theoretical reversing valve. All you really need to know is that with an oscillating engine, if you put air in port "A" and let the air go thru the engine and come out port "B" the engine will revolve clockwise. However, if you put the air in thru port "B" and let it run thru the engine and out port "A", the engine will revolve counter-clockwise. The third hole with no designation is going to be a pivot for a reversing lever.---Use your imagination---It helps.
(https://imageshack.com/a/img921/3081/rcKmf5.jpg)
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So here we have the reversing lever in position #1. Air flows in the green inlet tube, up thru a passage in the lever, and out a hole in the far side of the lever which is lined up with port "A". Air flows in port "A", thru the engine, and out port "B".---Engine revolves clockwise.
(https://imageshack.com/a/img921/8866/AWDRIA.jpg)
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In this picture, the reversing handle is at mid position. Air flows in thru green tube, up thru passage in handle, but can't flow out far side of handle because it is not lined up with port "A" or port "B'. Engine is stopped.
(https://imageshack.com/a/img923/8090/C0ipxp.jpg)
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In this picture, the reversing lever has been swung over until it lines up with port "B". Air enters thru the green tube, up thru the internal passage in the handle, into port "B", then thru the engine and out port 'A", causing the engine to run counter-clockwise. Remember, that hole at the bottom of the lever is for a "pivot shaft".--There is no air flowing down towards the pivot, ever.
(https://imageshack.com/a/img922/936/BYp5YB.jpg)
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So---As I said earlier, I have an idea for a reversing valve, but it is crude. Even under the best of conditions it would be difficult to keep air from leaking like crazy, and it is crude having the airline running to the reversing lever. I know it would work.--However---None of this is "new" stuff. I am sure that somewhere over the last 200 years, a far superior and simpler design must have been made. I am looking for that "simpler and superior" design now, and remember, it has to be something simple enough to be fabricated on a manual mill and lathe.---Brian
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I quite like that on Brian, easy to make. As you say the only issue could be
Sealing but with the surfaces lapped and if you can put a compression spring on the pivot it would have a decent chance. Probably only be a real issue in the engine stopped position. Getting more complicated but if you encapsulated it I.e. made something around the other side of the lever you could use a kind of lead spring to exert pressure right across whole lever rather than just where the pivot is.
Or, you could do something along the same lines with 2 discs. So when you rotate through that angle, holes in the discs line up for inlet / exhaust. If the pivot can be kept in the centre of the disc it would give you a better chance of sealing as the spring will exert a more even pressure.
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Not quite two hundred years Brian but here's one I did earlier - not rocket science and nothing magic just a bit of R/T work involved - no leaks at 30 - 40 psi
(https://lh3.googleusercontent.com/D2bqoNvXKMNZem2VTPQGj0hixATs_ebPLiQ83kA2HgYvCEiUP5l1m64CNiiPLg-tKfvZZ7eYQ8nEd5NqBCVmzwFavbby6QanDC9ko99lQWQ9V2dcrtxHpuGphCP-uaBy2Ww2XcM8xs8ObJZL4cgO8QbZ6MsFup0nQQQchIbMAjsc9eZb8VXK4YgaXe4_qcSyBjtDipt4CMZ4NF-6L-Q58h-gi5ZTG7lrxNAvPEisoI5hHDuWSGFO6_0AB1z1CaORaRF5kaXurWZHGKu5BWY4P0wcr-ZOttbvtbTo7cX6uJOA-PFfQIicN04-M-3ssHSJHyeXAFKRJtzemMRxINcnCDlerrdw9QTtYrbHGR-kCg7E-JEhaiGN9W27JKIK56d7RLiLgEbxgTeIHe4gCmRU43xN8kIJhzUyOCCOIm1QhXANsEj1Ae1_fmM-ABDl5gMuawuEMfO3qkDss8uPSh1zQb9IOFToMBW9YgNPLqnlL_7C20NhT7rt1tzOAyd360yMzCjiPPG39iLbi1UWFbGV3Azpt8_evqe5Osz4jRqqvpoBFOtmjqjhgA_jwARj9AX4PSY34RMYhewTbukfYu-2sRUO2x9TYQxfCosen2c=w1224-h918-no)
Works as you describe - one way to go one way, the other way to go the other and stops in the middle.
No drawings but the pic should be explanatory enough - inlet on one side, exhaust on the other top outlets to the engine (the two holes in the bottom are mounting holes) - as here...
(https://lh3.googleusercontent.com/4pcc_XAPJdErYVhdpE-fiOx6aWZaz5ekkX4RhWE8hkrd-u6YBw-YSpXbpONTW_tchyKRf9W0wJ57g4bEmT4kyrXvCQ99buab-_iQjjfSMpkLKbuAbojQMiPxFdoNzUjceYtNdsmengIAn3yWvRO0gPUYmEH9d9M4Tq6LUhMewQMCMy_SBIO8ok4Jjk5cgOyxrVLbvS6W3hXQUZyAt3mfB7S_qOZlVBTha079Z83EMY8F_PCYX0lqgoA7s0UF5AUUZdgMdMraKxu1MPMHafXXB8ARrqk7yuBCicPFfNjbZKCCILwGsQbXYQ2qsTn2sCiedmR6ZlyHgsLNWAJM2eanwjsMP5DpvISUDZHM0tl0ZQIz3d3okc0r8Mhy431b0B5N8rXeO0jz_1bUQj6ikaRpARG4VdbWwmmPp1DB9O-IcehGs1hJb1oY_nPfGzn5uqHIF4_QVKXIcaA7_6vDR-3B2Ti5DowsuEv2nyJknJdiVqB-Eo3mItGCu9lgKEy4KUljREbJhe5q3uluR0Ni1GEKsogVtrqTLKZgV9niGEve6iWLeAyJTH6SG_SDVZu7ipVBYj3LCQC5dWfgGoX5kXNY8XEDQJ4CRhBirEcwRMc=w1224-h918-no)
Hope that's of use - Tug
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Ramon--that's great. thank you.---Brian
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Ramon--I am trying to model this valve and figure out what the passages are in the bronze block. I wish I had x-ray eyes like Superman. Can you give me any hint as to what lines connect to which of the 4 visible ports? How far do you have to swing the handle to go from full clockwise to full counterclockwise. I am assuming that when the handle is straight up there is no steam passing at all and the engine is stopped.---Brian EDIT--EDIT--I think I got it. The ports going out to the cylinder are on the extreme right and extreme left on the face of the block. Air coming into the block comes out at the top port on the face of the block. Air exhausting from the block has it's port at the extreme bottom of the face on the block. You would have to swing the handle 45 degrees either way from the vertical position to make the engine run clockwise or counterclockwise.---i think!!!
(https://imageshack.com/a/img923/1944/442Ly9.jpg)
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Brian:
There is a Elmer's Engine #3 that is OPEN COLUMN ENGINE with Reverse that may give you a switching valve idea that you could use to make your "GREAT" engine reversible. Your modeling is very admirable and a joy to watch the whole process from idea to running engines. Thank You for your contributions to us Model Engineering folks.
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The 'ghost' model you posted there is exactly correct, Brian. Just like that...
Pete
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Very smooth runner and nice and slow Brian very nice engine indeed. Are the port caves running together both ally. I have some drawings of a reversing valves for engines that I’ve made if you want i can mail them
Stew
Stew--Not sure what you mean by "port caves". The frame is aluminum and has port passsages drilled in it. The rocking cylinders are cast iron and have the mating ports drilled in them, in typical wobbler fashion.---Brian
It was a predictive text error Brian it should read Port Faces, but you've answered the ? thank you, I think I have your email address so drawings will be sent that way.
Stew
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Simple piston valve would seal a lot better than your lever design Brian, take a look at Peter's (Gas Mantles) post a few days ago about how an engine reversed.
Muncaster also shows a simple reversing valve for his wobblers.
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It took me a while to figure out too, but came to same conclusion Brian, model looks correct.
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'Morning Brian,
I'm sure you have it as mine is as far as I can remember. The two connections either side are not in line vertically, the two outlets are.
It will act as a throttle but only over a very small radial movement - it soon allows a full flow of air through so perhaps a secondary valve on the inlet side might be in order for a more varied throttle control.
Glad to be of help - Tug
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Thanks to Raymon in the United Kingdom for sharing his rotary reversing valve design with me. I will probably build this. It only consists of two pieces plus the center pivot and handle.
(https://imageshack.com/a/img924/7824/WATxhG.jpg)
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I had hoped to start on this reversing valve today, but life got in my way. Had to take good wife out to buy a new patio umbrella, which turned into a patio umbrella and two wicker patio chairs. Then had to wash the rear deck before we could put the new chairs on it, then had to dismantle the old patio umbrella-----anyways, you get the idea. I did stop at my metal suppliers and check out a piece of 660 bronze to make the reversing valve out of, but decided that for $42 (which was the asking price) I could use a piece of aluminum I already have for the dark blue part and some brass that I already have for the round reddish colored part. That dark blue piece is 3/4" thick, and has more holes and passages in it than Mamoth Cave. My original plan was to have that round reddish colored piece 3/8" thick, however since I have 1/4" brass plate I may end up soldering two pieces of 1/4" plate together and make it 1/2" thick. I'll figure that part out when I get to it.
(https://imageshack.com/a/img921/904/FvwwC9.jpg)
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Work is progressing on the reversing mechanism. The first plate with all of the passages in it is finished, all except for the area at the top where the blue layout dye is. That will be filed to match the contour of the rotary plate which I hope to make tomorrow. A search of my brass drawer yielded a piece of brass 1/2" thick so at least I'm not going to have to laminate two pieces of 1/4" brass together like I originally thought.
(https://imageshack.com/a/img924/4315/GXt03L.jpg)
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Ramon--I'm going to tell you how I think your valve goes together. If I get it all right, then great. If I haven't got it right please speak up. The steel pivot shaft fits into the brass block from the far side, with the red o-ring under it's head. Probably the o-ring and the head set in a counterbore on the back side of the brass block. The o-ring isn't there to seal as much as it is to create a bit of pre-load between the face of the brass block and the face of the disc with the slots milled into it's face. This disc with the slots has a partial bore to fit the smaller "step" in the center of the pivot shaft. It also has a thread to match the thread on the end of the pivot shaft. The pivot shaft is restrained from turning (slot in far end for screwdriver maybe) and the disc with slots is tightened onto the thread until a fairly good pre-load is arrived at (from the crush resistance of the o-ring setting under the head). Enough thread on pivot shaft sticks out past outside of disc with slots to allow a hex nut to be threaded on, which acts as a lock nut to prevent the disc from unscrewing as it is swung back and forth to reverse the engine. I see that you have relieved the area on the brass block that is not part of the "mating face" and that you have a ring of material on the "disc with slots" that fits down around the mating face on the brass block. I think that is more cosmetic than a sealing lip, but I'm not sure. The o-ring will also seal any pressure trying to sneak back around the pivot shaft and escape out the back side.--Is this about right?---Brian
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Morning Brian, Yes you have that dead right :ThumbsUp:
As you say the lip on the disc is not important and can be done away with - the rest of it is as you describe.
I'm off early for a day at a model show so will look in tonight to see how you got on. Apart from the odd look on here I've had little to say for some time - pleased to say that hopefully the causes are at an end and I'll be back in the workshop this week :)
Regards - Tug
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Thanks Raymon--You are a great guy for sharing this knowledge.---Brian
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This morning I finished the reversing disc. In the "set up" picture you can quite easily see that the slot on one side was cut with a 4 flute endmill that was duller than a hoe. The other side was cut with a new 2 flute carbide endmill. And of course, the all finished shot. Now I have to go and take two grandchildren to a live play of "Cinderella" at our community theater. I liked the Grimm's fairytale version where the ugly stepsisters cut off their toes with the axe to try and get the slipper on.--Might not set well with todays audience though, I suppose.
(https://imageshack.com/a/img924/3649/cEk2hW.jpg)
(https://imageshack.com/a/img923/2203/hsX6ef.jpg)
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Today I successfully completed my first reversing valve. These valves are not difficult to build, but the set-up is a bit fussy so that the valve doesn't have any major air leaks. A gentleman in the United Kingdom was kind enough to send me a picture of a disassembled reversing valve that he had built, and that served as the basis for my design. Thank you, Raymon. The video shows me operating the reversing valve, and I must say, I am very pleased with it.
https://www.youtube.com/watch?v=hy4R43Oqew4
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That is working great Brian, I think these can be operated by solenoids for boats etc. I have a question though, do you think there is a leak somewhere? It’s sounds a bit hissy compared to your previous video where I could hear a much more distinct exhaust beat.
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Yes, it's a bit hissy. The "hissy" is happening between the mating faces of the rotary disc and the reversing valve. They should have been lapped better.
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Brian, I like your engine and it seems a good runner but I don't think the difference in running speeds forward or reverse has much to do with the way it has been run in.
My guess is there will be some very small asymmetery in the way it has been machined. It would seem to me the probable difference will lie in the reversing gear, are the arc slots a perfect match ?
What does it run like in forward and reverse if you bypass the reverser but swap the inlet / exhaust connections ?
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Congrats on a good result Brian :ThumbsUp: glad to have been able to help in some small way. Thanks for the acknowledgement on the video - that's a first for me ;).
The valve faces do need to be well lapped to each other and the mating should not be influenced by the pivot thread/tightening for best results ie the two faces need to pull up truly flat to each other.
Regards - Tug
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That is working great Brian, I think these can be operated by solenoids for boats etc. I have a question though, do you think there is a leak somewhere? It’s sounds a bit hissy compared to your previous video where I could hear a much more distinct exhaust beat.
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Nick--If I was deeply troubled by the hissing, I do have room for one more o-ring around the rotary disc, out beyond the air passage slots. I have shown a "standard size" 1 3/8" x 1 1/2" o-ring groove x .045" deep. I just don't know if it's worth the bother. It is difficult to buy individual o-rings in specific sizes.
(https://imageshack.com/a/img923/593/0OWrCa.jpg)
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An o ring there might make it worse, lifting the plate slightly and giving crosstalk between the ports, though if the center bolt is tightened that could be minimal. Seems like lapping would be enough.
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Now that the excitement has died down a little, I have been analyzing what is happening here. The faces of the moving disc and the stationary part of the valve must fit tightly against each other at all times to prevent air loss. This is not happening. When the engine is revolving in it's original direction, there is very little air leakage at the reversing valve. However, when I swing the handle thru a 90 degree arc to run the engine in the opposite direction, there is a lot more air escaping from between the valve faces, and that is the reason the engine is running slower, contrary to what I first thought. I believe that the reason for this may be that the faces are held tightly together by a thread cut on the outer diameter of the pivot shaft and the inner diameter of the rotating disc.--I have never had a lot of luck getting a threaded connection so perfectly square to the rotational axis that the pressure is equalized all around. There are a couple of ways I can think of to make a better seal. One would be with an o-ring slot milled around the circumference of the rotary disc as shown in the previous post. The o-ring slot would be cut to about 75% of the o-ring's cross sectional diameter, so that when the threaded sections were screwed tightly together the o-ring would be for all intents crushed flat. Then if rotated thru 90 degrees and there was any loosening of the two pieces the o-ring would expand to "fill up the gap". That is probably the solution that takes the least amount of work. A second way would be to remove any threads from the inner diameter of the rotary disc so it is free to slide on the pivot shaft, and have a longer threaded end on the pivot shaft with a small die-spring captured between the hex nut and the face of the rotary disc. I have to ponder this for a while to decide what I will do.
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Brian, that's a great engine!! Congratulations! :cartwheel:
Air leak: I found that, using your reversing valve for example, if you open the clearance hole in the disc so it's, say .02" (.5mm) bigger than the shaft, that it will no longer dictate position and let the disc sit flat on the mating surface. The radial positioning on the valve, or the cylinder of the oscillator, is much less important than letting the disc seat properly. Then a little spring will hold the seal tight.
I would NOT use an o-ring. Besides the o-ring trying to lift the valve off it's seat it introduces a drag element in to the 'shifting' of the valve. This is something the RC boat guys try to avoid because servos have limited power.
The other part is making the seal surfaces mate right up to the passage ways, otherwise pressure can get in the much larger area and make more force trying to lift the valve off it's seat.
I hope I'm making some sense here....
Love your work!
Pete
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Have the valve disc a free fit on a parallel pivot that is only threaded at the end for a nut with a spring under it, same as seals your cylinders so use the same simple method to seal the valve. That small O ring in Ramon's photo provides the small amount of "spring" pressure to hold his disc to the port face and it pivots on the plan section of the shaft, though he has it under the head of the shaft not the nut.
As said if you use the O ring as drawn and there is any lift between the face and valve disc air will just flow across the face from inlet to exhaust as the o ring expands to fill the gap.
(https://www.tapatalk.com/groups/modelsteam/imageproxy.php?url=http://i895.photobucket.com/albums/ac154/gaynorandtony/Paddle%20Wheel%20Engine/031PaddleWheelengineregamprevvalvefittedLR_zps96f29893.jpg)
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I agree with the guys, well lapped surfaces, clearance in the pivot hole and spring to keep them together. In off position spring needs to be strong enough to prevent the pressure from pushing discs apart.
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Okay Guys---Good advice. I drilled the threads out of the rotary disc, and opened up the 1/4" diameter that was a "precision fit" on the 1/4" pivot shaft x about .005" . I found a couple of little compression springs and captured them under the hex nut so they bear against the front side of the rotary disc. This is going to work, and quite well I think. It still leaks a bit around the edges of the disc, but it's dramatically reduced.--And--If I apply a little more pressure with my thumbs on the face of the disc, the air leakage totally stops. I will go down to the company where I buy my springs and pick a heavier compression spring this morning. The compression springs I have on hand are a bit wimpy, but are strong enough that I believe this operation is going to be a success. thank you for the advice and suggestions.---Brian
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Just got back from my spring people with a very stiff little compression spring and installed it under the hex nut. The air leak is completely gone.---And yes, it runs the same speed in both forward and reverse. The new spring is 0.040" diameter wire x .3125" outside diameter with a 0.050" pitch when free and a free length of 1.1". In it's fully compressed state it is 0.350" long. Again, thank you to everyone for their help.---Brian
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:ThumbsUp: :cartwheel:
Pete
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Brilliant, nice work Brian. Will you have time to do a final video?
I’ve just seen two cast iron brake cylinders that were the wrong ones for my car in garage and it got me thinking about big wobbler cylinders! There’d be a few holes to block though - do able or a waste of time and better starting from scratch?!
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Nick--I've seen it done, but--Considering the low cost of round cast iron, you would save $20 worth of material to do 50 hours of extra work. Yes, I will put up a final video. I'm machining a fancy "bullet" nosecone right now to cover the spring and hex nut.---Brian
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I was thinking the basic shape and the bore is there, would it save a lot of machining or could just cause more needing to block up holes etc!
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I don't advise it.---Then again, I don't make the rules. Try it and see. You have nothing to loose but your time.---Brian
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Thanks, I agree. That might be the way forward, just try and machine one, as the first part - if it fails, throw it in the bin and start from scratch with no compromises!
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A word of caution here---People are buying plan sets for this engine, and I have been explaining to them that in it's current state there is really no good way to have a power take off from it to run anything. If people want to use a belt drive to power something using this engine, then three parts have to change. The crankshaft, spacer angle, and manifold all have to be 1/2" longer. This allows room for a 1/2" wide pulley to set beside the flywheel so the engine can be used as a power source to drive a belt. Tomorrow I will add drawings for these three items to the design package.---Brian Rupnow
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And if you were wondering---this is the engine with the power take-off modification. Basically, what it means is that the two angles which make up the main frame of the engine are 1/2" farther apart. This gives room for the red, 1/2" wide power take off pulley.
(https://imageshack.com/a/img922/6564/9UGSPH.jpg)
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Why not just specify a flywheel cut from steel or Cast Iron bar then it can be made narrower than your lightweight alloy one and there will be room for a pully though it still needs the ending stripping to fit belts.
Or as your red pully is no wider than the boss on the crank arms why not change one crank arm to a disc, cut the belt groove into it and just drill for the crank pin. Or just make the light green crank boss a larger diameter. That way you only need to undo the crank pin to get a belt on and off.
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I think it's better just left as display engine rather than one to do work. The design as it stands doesn't lend itself to belt driving so any modifications are likely to detract from the appearance.
It's not really practical to strip the engine down to change belts and once one is fitted it won't look right unless it is driving something.
The idea of adding the pulley will mean the flywheel is no longer central in the gap and spoil the symmetry.
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Yes, but the straight crankshaft pulls straight out of the engine. Just loosen of the set-screws in the crankshaft and it pulls straight out of the engine allowing a belt to be installed. It takes about 10 minutes. The engine was never designed to drive anything. It was built for the beauty of the engine itself. I am just reacting to customers requests.
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I have been asked by a forum member to post a video of the engine running with the new "Leakproof" reversing valve design. Here ya go---
https://www.youtube.com/watch?v=qgzw0y9IZes
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Spot on Brian, no leaks, same in either direction and the exhaust beat is back.
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Oh my god---A GIANT BRAIN FART!!!!! I spent a goodly share of yesterday designing all of the components required to widen the engine and add a take off pulley beside the flywheel. Got up this morning and looked at it and thought "I could just put the pulley on the crank arm without changing anything else". Musta been that funny stuff I was smoking yesterday---
(https://imageshack.com/a/img923/2934/bMYJJP.jpg)
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You sure you did not read my suggestion to do that first? ;)
"Or as your red pully is no wider than the boss on the crank arms why not change one crank arm to a disc, cut the belt groove into it and just drill for the crank pin. Or just make the light green crank boss a larger diameter. That way you only need to undo the crank pin to get a belt on and off."
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Jason--Honestly, I didn't read that. It just struck me like a bolt out of the blue this morning, and of course I felt like a complete idiot. Fortunately, any of the plans I have sold so far did not include all of the changes I dreamed up yesterday. I only wasted my time, and right now time is something I have way too much of. I do appreciate the picture you posted of the spring between the hex nut and the reversing disc.---Brian
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Nice addition to your engine. Looks like a neat little valve that works great! :ThumbsUp:
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Thanks Craig--I am impressed by how well it works. and it is one more thing to add to my stable of facts about "little engines".---Brian
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Great addition to an already nice design Brian. Well done !!
Bill
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Today I was bored, so I decided to go back and address the subject of "running something" with my oscillating engine. I took 20 minutes to machine a pulley and added it to the crank arm on one side, then set up my "Crazy Joint" for a demo video.
https://www.youtube.com/watch?v=RNwpUGp89SE
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If anybody would like to build that crazy joint, I have a complete set of drawings for sale for it. Contact me at brupnow@rogers.com
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Great fun seeing the engine drive that - very smooth, very intriguing. Cheers!
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Excellent! Very nice runner, and that crazy joint is a fun thing, they have a full size one at the steam show near here in August, but its not connected to the engines near it, just on a handwheel.
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I've had a few questions about the "crazy joint". I modelled it in 3D, then animated it. It's kind of hard to get your head around it even when you see it in operation. And--whatever camera effect makes the stage coach wheels revolve backwards is still in play. I would have thought that would be overcome by now, but apparently it hasn't.----Brian
https://www.youtube.com/watch?v=B72Y4wnqqJE
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A heads up to all of you who are currently building this engine from my plans. When I designed the pulley which fits over the crank arm, I put a set screw in it, but failed to realize that with the pulley in place there was no way to access the set screw in the crank arm. So, a clearance hole has been added to the pulley to allow access to the crank arm set screw.---Brian
(https://imageshack.com/a/img923/3286/huaFw5.jpg)
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I have a three ball governor that I designed about three years ago. At the time I designed it, I was looking for a way that I could change the rpm setting while the governor was working, not setting still. I was successful in doing that, by adding a pair of tension springs to the output lever to counteract the compression spring on the main post. Since this type of governor will work in either direction, I may try marrying it to the double oscillator engine.
(https://imageshack.com/a/img923/7250/JvdAFt.jpg)
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I have just spent much of the morning remaking a 3d model of the three ball governor. I don't know how it happened, but I had completely lost my original SolidWorks files on this governor. So---It was a matter of chasing down existing .pdf files, printing out some old drawings I had posted about 8 years ago on the forum, and measuring my existing governor. I'm not totally finished yet, as I have to add in the steam control valve, but I'm a lot closer now than I was early this morning.
(https://imageshack.com/a/img922/5629/CFvXot.jpg)
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Here we go. A few compromises here, as I am working with an existing governor. The governor in it's current state as shown in the earlier photograph is not set up for a steam valve. I have to remove the adjusting counter-springs and add on the steam valve components.
(https://imageshack.com/a/img921/4569/Kez8xM.jpg)
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Very interesting configuration, Brian. It would be neat to re-work the existing gov to add the steam valve and then put it to the test!
:cheers:
Pete
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Okay--Going to look sorta/kinda like this. I'm a bit surprised--the scale doesn't look all that bad, considering the oscillator and the governor were built a few years apart. If I go ahead and do this I may have to move the dark blue steam inlet/outlets around a bit on the governor.
(https://imageshack.com/a/img922/5400/lyrF7t.jpg)
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That looks real good.
Have a great day,
Thomas
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This morning was time to do some "real world" tests of the governor, to determine what the maximum rpm needed to be for the stem-post to turn at, in order to get full travel of the pivoting lever arm which controls the steam valve. The video explains this as I drive the governor through it's full range of movement.
https://www.youtube.com/watch?v=a0Sald9f5Es
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Very interesting to see, thanks!
I always thought that the governor had to be vertical, but you ran it horizontal. Is the spring you used strong enough to make gravity irrelevant for the movement? I never knew that springs were used in them, my brain needs a rethink...
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That type of governor will run either vertical or horizontal. The spring negates any effect that gravity would have.
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In order to mount and drive the governor at the right speed, I will have to use a "bend pulley" which mounts to the side of the main frame with a shoulder bolt. This will keep everything (the o-ring drive belt) from interfering with the oscillating cylinder.
(https://imageshack.com/a/img922/6799/ilztRI.jpg)
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Thats going to be great!
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Doing a bit of "real time" testing here to see if the governor is spinning fast enough to take advantage of it's full range of motion with the engine running at a reasonable rpm.
https://www.youtube.com/watch?v=ocC4o6EXrfw
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Very neat! :ThumbsUp:
Is there a link to the origins of your governor?
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Very neat! :ThumbsUp:
Is there a link to the origins of your governor?
Zee---This is the link
https://www.homemodelenginemachinist.com/threads/3-ball-governor.9474/
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Very interesting result this morning. I tried exactly the same test this morning (as shown in the video) but with the compression spring removed from the stem post. This gave full movement of the governor arms as I wanted, and made the governor much more responsive at a lower speed. Gravity seemed sufficient to return the balls into "low speed" mode when I slowed down the engine. The only thing I am absolutely sure of after dicking around with mechanisms like this for 50 years---Gravity only works when you are watching it. As soon as you turn your back, something screws up. I'm off now to buy a lighter compression spring.
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Thanks for the link Brian.
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I have spent the entire day fitting the governor to the engine, building and mounting a bend pulley, and changing out the spring on the stem-post for a lighter spring. I'm happy with the results so far, but it has eaten an entire day to get to this stage.
https://www.youtube.com/watch?v=4xsOk4-D2zY
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I'm happy with the results so far, but it has eaten an entire day to get to this stage.
A day well spent I'm thinking. It's a neat looking governor.
What are the advantages to this design versus the traditional two-ball governor?
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Zee----Non really. I just think they look neater.---Brian
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Zee----Non really. I just think they look neater.---Brian
Works for me! :ThumbsUp:
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Hi Brian, I'm with Zee, a great days work. And well worth the time experimenting to get that spring stiffness right.
I think you will find that the three ball design means you get the force from three balls under centrifugal force instead of two. This should give you about fifty percent more force to operate the throttle valve. This may make all the difference if you have a gland on the throttle valve that is a bit tight in order to seal.
Similarly, with the governor shaft vertical, gravity is holding all then balls downwards, so the governor has to spin faster to force the ball weights outwards. If the shaft is horizontal, gravity helps the balls move out while below the centre line but tends to hold them in in the top half of the revolution, so reducing the average effect of the weights. I would expect this to make for a more sensitive governor at low speed, but probably less force available to operate the throttle valve, and perhaps less stable.
A great thread,
MJM460
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Either the parts are getting more complicated or else I'm getting slower.---Probably both!!! I made the new front end for the governor (which will be part of the steam valve), and made the brass bushing that lines it. In the middle of all that my lathe quit, and when I went to check the glass fuse the entire fuse holder fell apart in my hands.---Fortunately for me, I knew that they had plastic fuse holder assemblies at Sayal electronics across town, so I went over there, bought one, brought it home and after a little soldering and finessing my lathe was up and running again.
(https://imageshack.com/a/img923/6092/Zjlu8D.jpg)
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I spent 8 hours today doing a 1 1/2 hour job. BAH!! HUMBUG!! OINK!!! The steam valve started out with a center rod 3/16" diameter.--It leaked. Then we went for a 7/32" center rod---it leaked. Then we tried a 1/4" center rod---it leaked. Finally I went with a 9/32" center rod and it leaks such a small amount that I think it is acceptable. And of course every time I went up 1/32" in rod diameter I had to go up 1/32" in reamer size for the rod to fit into. Days like today I wish I had taken up needlepoint as a hobby instead of machining.
(https://imageshack.com/a/img924/7537/ZybXJZ.jpg)
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I'm pleased to report that the governor works quite well on this engine. For projects that were built 3 or 4 years apart and never intended to run together, they work together quite well. I have some clean-up work to do and some pivot pins to shorten, and then I will make a video to post.---Brian
(https://imageshack.com/a/img921/9963/BGe1Fn.jpg)
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Hi Brian,
Looks real good on top of the engine, great job.
Have a great day,
Thomas
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And here, as promised, is a final video of the 3 ball governor running on the dual oscillating engine.
https://www.youtube.com/watch?v=Gbl3XxCJbP0
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Hi Brian, wonderful explanation and demonstration of how it all works - excellent!!
Chris
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:ThumbsUp:
Very cool video Brian, thanks for posting this.
John
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You have to feel pretty cool about that one.
Doing a project some time ago without knowing the future and then being able to apply it to a new project...that's pretty cool. :ThumbsUp:
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Nicely done Brian!
Dave
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Thanks guys. I've done this thread right to death now. Hope to stay out of the machine shop for a couple of months now.---Brian
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Hey Brian, what is the diameter of the disc on your reversing valve? Looks like about an inch?
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Chuck--That reversing valve worked so well that I started a separate thread on it with full details.---Brian
http://www.modelenginemaker.com/index.php/topic,8226.msg176712.html#msg176712
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Excellent log of the build of this fine and solid engine.
It's a beauty!