Author Topic: Arnold's take on the MEM Corliss  (Read 134672 times)

Offline Maryak

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Re: Arnold's take on the MEM Corliss
« Reply #270 on: June 16, 2013, 01:39:43 AM »
Nice work as always Arnold, :praise2:

Vince,

Unless I'm misunderstanding, if one end is fixed then I think the adjustment is limited to half turns to line up the other end.................???

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline vcutajar

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Re: Arnold's take on the MEM Corliss
« Reply #271 on: June 16, 2013, 04:49:24 AM »
Yes Bob you are right and every half a turn it moves in or out (depending which way one turns it) by 0.25mm.

Vince

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #272 on: June 16, 2013, 06:51:12 PM »
Thanks Bob & Vince  :)

Vince, you're quite right; it may not be needed to add additional fine adjustment.  Between the "differential" created by the pivot arm for the main rods, it may just be possible to use adjustments on either side; adjusting on the eccentric side by 0.25mm will make the other rod move more than that, but then, on the other rod, the adjustment is pretty much "infinite", as it's connected to the valve disk using the pivot and a grub screw...  So no need to really faff around too much  :)
As for adjusting the rods going from the disk to the valves, this is also not really needed; one only needs to turn the valve in the arm that connects the rod to it.  I think we're over-complicating things  :Lol:

I started work on the eccentric strap today.  Digging around, I could not find suitable material to make it from as a whole part, so I settled on making it as an assembly.  I had a bit of suitable phosphor bronze bar on hand to make the "round" section from; it's slightly smaller than the plans, but should be fine.  I cleared the skin off it on the lathe:


Next on to the mill, and I drilled a 5mm hole about 4mm deep into it, as well as touched a 4mm end mill on either side to form shallow pockets:


I turned up and threaded a short section of brass rod to 5mm OD and M3 on the inside, and then drilled a 2mm hole into a piece of 4mm brass and parted of two 6mm long sections:


Some Silver Soldering done:


I didn't bother to pickle that lot to get it totally clean; just enough to get rid of any flux left.  Then onto the mill again, and I used a 0.5mm slitting saw to run through the center:


The workpiece was placed vertically in the vise, and I used the height gauge to set the slitting saw height to chop off the top:


I ended with this lot for the day:


In my next shop session I'll stick that lot in the 4-jaw chuck and bore it to size.  The 0.25mm either side that it's "out of round" from using the 0.5mm slitting saw will be barely noticeable, and some judicious strokes with a file will hide even that.  Right now it looks a bit rough, but it should come out OK once finished.

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline Jo

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Re: Arnold's take on the MEM Corliss
« Reply #273 on: June 16, 2013, 07:08:15 PM »
Looks good Arnold.

Did you get over enthusiastic with your silver solder at one point there  :???: The way around it is to cut off a small piece and lay it in the flux then apply the heat. That way you can control the amount of silversolder and have less to clean up after, it does not stop you poking  :stickpoke: a bit extra in if you feel the need  :D

Jo
Usus est optimum magister

Offline vcutajar

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Re: Arnold's take on the MEM Corliss
« Reply #274 on: June 16, 2013, 07:10:01 PM »
I am seeing a nice strap there.  I am really enjoying this.  Seeing the same parts being made in a different way.  Really educational.

Vince

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #275 on: June 16, 2013, 07:36:22 PM »
Thanks Jo.  You're dead on the money; a slight bit of inattention and I'd tapped the rod in the wrong spot.  I still have problems with cutting bits of and placing them; when the flux starts to bubble the bits go all over the show and away from the joint  :???: .  I still need to get some of that thin silver solder available overseas.  Once I have a bit of a stash built up I'll order in, but for now, the stash is depleted as I still have to pay import duties and VAT on a new "toy" that should be arriving in the next couple of weeks...

Vince, thanks.  Yes; we're all building the same "thing", but in different ways.  No mass-production here; one-off originals for each and every person who builds something  :)
It's all part of the fun of this hobby; there's just some basic "rules" and after that everyone can do as they see fit with whatever they have available  :ThumbsUp:

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline Jo

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Re: Arnold's take on the MEM Corliss
« Reply #276 on: June 16, 2013, 07:47:20 PM »
I still have problems with cutting bits of and placing them; when the flux starts to bubble the bits go all over the show and away from the joint  :???:

Start by just warming it slowly to get the flux to dry and you will find it will stick the solder to the joint. I normally make little loops around the things I am sticking that way they don't go walk about. The other thing worth sometimes doing is flattening out the bit of silver solder with a hammer ;)

Jo
Usus est optimum magister

Offline arnoldb

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Re: Arnold's take on the MEM Corliss
« Reply #277 on: June 23, 2013, 08:35:35 PM »
Thanks Jo; I'll give that a try as well  :) .  One thing I keep forgetting is to try and make up my own "silver solder paste" by filing a bit of solder down over a bit of paper to catch the filings, and then mixing it with flux.  Have to experiment with that one as well at some stage...

Yesterday was a lost cause; I had to pay attention to other matters, but today I got some more bits done.  First of was more work on the eccentric strap; first, I marked the center:


Then clocked it up in the 4-jaw, taking care not to be too heavy-handed while chucking it up:

 ::) I REALLY need to make a pump-center...

I very carefully drilled it out to 10mm - keeping the feed rate low to prevent the drill "grabbing" in the bronze , and from there used a small sharp boring bar to bore it to final size.  The eccentric ended at 22.05mm, so I bored this to 22.1mm to give a bit of room to form the bearing surface:


Not exactly a thing of beauty after clean-up, but it will do for now.  I'll make smaller nuts; the standard M2 nuts are too big:


It turned out to be a very nice fit on the eccentric; turning smoothly, but without discernible play:


Next, a bit of 2mm brass plate for the lever arm.  The plans call for 1.5mm, but I had a choice of 1.2 or 2mm, and the 1.2 could be a bit flimsy, so I went with the 2mm.  Holding smaller bits of plate like this for drilling can be problematic, but it's a breeze on the tooling plate I made:


Some rounding-over and a bit of clean-up, and the lever was done.  the bigger 3mm hole on the one end is not exactly to plans; I made the thread in the base for the pivot M3, hence the larger hole:


Like Vince mentioned, the forks for the two eccentric rods are identical, so I also made them as a pair from some 12.7x4.7mm (1/2" x 3/16") brass flat bar I have.  I used the edge finder to find the middle of the bar on the Y-axis, and the end on the X axis.  I started to mill the center out wit a 2mm slot drill, but after I reached about 5mm deep, it snapped...  On the 6mm deep level, another one snapped, even though I was very careful with the feed-rate.  Not wanting to break my entire supply of 2mm mills on these pieces, I decided on another tact.  I set up the vise stop so I could flip the workpiece upside-down, and drilled and tapped the M3 holes for the rods - leaving 1mm additional gap between them for a 1mm slitting saw to slit the two bits apart:


Then I slit off the two still-joined pieces from the parent stock at the needed length, and once again reverted to the tooling plate; clamping down securely on the end of the workpiece in the area that would not get material removed.  I didn't want to have the workpiece come loose once I started removing material.  I finished the slots with a 1mm slitting saw (that's the thickest I own) - one cut top and one cut bottom:


Then I slit the pieces apart - leaving the tiniest little burr keeping them together.  It saves having to play hide-and-seek on the shop floor to find the workpiece as it gets flung away if fully slit off... :


Some more rounding over and clean-up, and I had the two forks.  I just noticed there's still quite a big scratch left on the right-hand one  ::) :


A bit of 3mm stainless steel volunteered to get threaded either end with a tailstock die holder, and I had one eccentric rod.  I intentionally left it slightly long at this point:


The results of today's work assembled together.  Broken slot-mill shanks makes nice holding-together pins  :LittleDevil: :


I couldn't leave it at that, so I disassembled the engine a bit first.  When I made the bits of the frame, I didn't tap the one bearing mounting hole, nor the thread for eccentric pivot, so I quickly, but carefully, did those.  Then I loosely assembled things again, with the eccentric set roughly at 90o to the crank, and checked how far the eccentric lever pivoted to either side from "straight-up" while turning the flywheel.  As mentioned earlier, I left the eccentric rod a bit long.  I had to shorten it by another 2mm and add four turns of thread to the eccentric rod, and things ended up pivoting evenly and equally both ways by eyeball MK1.  That should just about do for adjustments on "this" side of the eccentric pivot.

From a top assembly view, you can see that I need to move the eccentric slightly more toward the flywheel to get it in it's correct place:


The pivot rod is pretty much upright at the full piston travel to either side of the cylinder:


Still crude, but it's slowly starting to resemble an engine  ;D :


One thing I would do differently if when I have to do it again is for the screws/bolts on the eccentric strap.  Rather than drill clearance through both parts to use a bolt or screw with a nut, I'd drill through the "flywheel side" for clearance, but tap the "engine side".  It was a real bugger to get the bottom nut into place for installation; I eventually resorted to contorting my index finger with a dab of grease on it to hold the nut in place through the flywheel to get the nut into position. Once I make the smaller nuts, that will be a heck of a load of "fun"!

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline Jo

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Re: Arnold's take on the MEM Corliss
« Reply #278 on: June 23, 2013, 08:44:26 PM »
Nice Arnold  :ThumbsUp:

Best to avoid those very small suicidal milling cutters if there is some way to get a slitting saw to do the job  :D.

Looking forward to seeing your pump centre come together it is only a 10 miniute job..

Jo
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Offline b.lindsey

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Re: Arnold's take on the MEM Corliss
« Reply #279 on: June 23, 2013, 08:47:31 PM »
Another wonderful update Arnold. The ecentric strap looks perfect as does the assembly shot...nothing crude about any of it...lovely work on every part!!

Bill

Offline vcutajar

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Re: Arnold's take on the MEM Corliss
« Reply #280 on: June 23, 2013, 08:56:37 PM »
Nicely done Arnold.

Vince

Offline NickG

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Arnold's take on the MEM Corliss
« Reply #281 on: June 23, 2013, 09:43:33 PM »
It's looking great Arnold, thanks for the update.

Offline Captain Jerry

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Re: Arnold's take on the MEM Corliss
« Reply #282 on: June 23, 2013, 09:47:51 PM »
Nice work, Arnold. Its looking very good.  Here is a tip for getting to the bottom screw on the strap.  Disconnect the clevis at the lever end and flip the eccentric rod over so that it is pointing the other way.  Then the bottom screw becomes the top screw.

Jerry
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Offline Don1966

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Re: Arnold's take on the MEM Corliss
« Reply #283 on: June 23, 2013, 10:59:25 PM »
Beautifully done and well presented Arnold. Great progress a usual and she's shaping up nicely. Well done  :praise2:.

Don

Offline swilliams

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Re: Arnold's take on the MEM Corliss
« Reply #284 on: June 24, 2013, 06:40:57 AM »
It's shaping up great Arnold. I notice you have a shot with your shoes in it, that's not one of Bob's design features is it??  :LittleDevil:

Cheers
Steve