Model Engine Maker
Engines => Your Own Design => Topic started by: Brian Rupnow on August 28, 2018, 06:09:17 PM
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I am going to build a model drag saw. The power for this saw will come from the second i.c. engine I ever built--The Kerzel hit and miss engine. There are so many things that I don't know about a drag saw that it makes my head vibrate, but I am a fast learner. I am going to use a driving mechanism similar to the one in the attached picture. One of the first things I have to design is a "dog clutch" which enables me to shift a lever and put the engine "out of gear" so that I don't have to shut the engine down to stop the saw blade moving. I have at one time or other built everything in a drag saw (on other machinery) except for a dog clutch. Since I have the capability to cut my own gears, this saw will have a gear drive instead of a sprocket and chain. If you like this sort of thing, then follow along. Parts of this story may be boring, but parts of it will be something new.
(https://imageshack.com/a/img923/2166/8wd8Ep.jpg)
(https://imageshack.com/a/img921/7920/WQkuN6.jpg)
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Excellent!!
If you need any details about how they work, there are lots of patents about them that you can find on Google Patents, they usually have great diagrams of linkages.
:popcorn: :popcorn: :popcorn:
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Hi Brian.
I too will be watching with interest.
The " dog clutch " was the el cheapo version apparently. More sophisticated saws had a friction clutch which massively reduced the impact on the engine whilst engaging the blade to cut.
Having actually driven a full sized Witte engine powered saw they are rather a handful. You hold the blade off the cut using an extension to the top linkage in your right hand whilst engaging the clutch with your left. Now you're right arm is going back and forth as you gently drop the blade onto the log. Not for the feint of heart, I can tell you!
Oh, don't forget that the connecting rod is made of wood. It's a safety device, designed to snap if something goes radically wrong.
Cheers Graham.
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This first bit is a head scratcher. Where do I start?--well, the green colored part is the available shaft end and flywheel hub on the side of the Kerzel opposite from the governor weights. It is 3/8" diameter x 1.125" long. The brown colored part is a steel shaft extender 3/8" i.d. x 7/16" o.d. that slides over the Kerzel shaft and is pinned there by a 3/32" diameter cross pin. (And maybe some Loctite). The dark blue gear is a 24 dp x 20 tooth gear which has an internal bore of 1/2" and has a bronze bushing (red color) pressed into it. It also has three "dogs" machined on one side. It actually "floats" on the shaft extender and is not keyed to it in any way. There is a shoulder on the end of the brown shaft extender which the gear rides up against. The pink part is a steel sliding bushing with three "dogs" machined on it that will fit into the three slots between the dogs on the blue gear. It has a "groove" machined into the outer diameter, which a pair of pins on the shift lever fit into. It is capable of sliding along the shaft extender, and is also keyed to the shaft extender so it can not rotate freely. (I haven't quite worked that last bit out yet.)
(https://imageshack.com/a/img924/562/kz2xrr.jpg)
(https://imageshack.com/a/img921/1961/Z1NDt5.jpg)
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You will find it slips into drive easier if one side is sloped.
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Okay---I got it!! Two pictures here, one with dog clutch engaged and one with dog clutch disengaged. The green cross-pin on the extreme right hand end is for my electric starter.
(https://imageshack.com/a/img924/316/1YfMgh.jpg)
(https://imageshack.com/a/img923/5306/rHunxg.jpg)
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You will find it slips into drive easier if one side is sloped.
Thank you Jason. I've never made one of these before.
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Hey Brian
You had me thinking in the totally wrong direction first. What I had in mind by reading "drag saw" was some kind of powertool dragster saw :Lol:
Something like these:
https://www.youtube.com/watch?v=b5TN75_k8x8
But I just learnt what a drag saw actually is :embarassed:
With your clutch: don't you make it extra complicated that way?
I would make the dog and the gear one part. That way the coupler doesn't need to be able to slide sideways while the already has a bushing (wich of course can slide and rotate at the same time)
Florian
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This is it for today. Since I have now modelled the dog clutch, I will decide whether to stop designing and make some real metal parts or do some further design tomorrow.
(https://imageshack.com/a/img921/9817/Jh9NT4.jpg)
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I may very well put a ramp on the driving dogs. I just did a little test out in my main garage. I put a spruce 2 x 4 in my vice and got one of my handsaws. My son was here and had a stop watch built into his cell phone. I sawed at what seemed to me to be a reasonable speed, and he timed me for three different 10 second intervals. Seems like 14 strokes per 10 seconds is "reasonable". Six times 14 equals 84 strokes per minute. The ratio between my two gears is 108 divided by 20 equals a ratio of 5.4 to 1 So---5.4 x 84=453 rpm at the engine crankshaft. I don't remember what speed my Kerzel engine runs at, but I will probably start it tomorrow and check it with a laser tachometer. I know my single cylinder flathead engine runs at about 1000 rpm. I think the Kerzel runs slower than the flathead, but I will have to check it and see. If I have to have a second stage gear reduction built into this drag saw to make it work, I would much rather know now at the design stage than after it is all finished.
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Oh goody.... :popcorn: :popcorn:
Hi Brian,
Following along!
Cheers Kerrin
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First thing to do this morning was machine ramps on the driving dogs. Others have told me this makes the dog clutch much easier to engage. Now I'm off to my garage to start the Kerzel engine and decide what rpm it runs at.
(https://imageshack.com/a/img924/792/k8CjJU.jpg)
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This first bit is a head scratcher. Where do I start?--well, the green colored part is the available shaft end and flywheel hub on the side of the Kerzel opposite from the governor weights. It is 3/8" diameter x 1.125" long. The brown colored part is a steel shaft extender 3/8" i.d. x 7/16" o.d. that slides over the Kerzel shaft and is pinned there by a 3/32" diameter cross pin. (And maybe some Loctite). The dark blue gear is a 24 dp x 20 tooth gear which has an internal bore of 1/2" and has a bronze bushing (red color) pressed into it. It also has three "dogs" machined on one side. It actually "floats" on the shaft extender and is not keyed to it in any way. There is a shoulder on the end of the brown shaft extender which the gear rides up against. The pink part is a steel sliding bushing with three "dogs" machined on it that will fit into the three slots between the dogs on the blue gear. It has a "groove" machined into the outer diameter, which a pair of pins on the shift lever fit into. It is capable of sliding along the shaft extender, and is also keyed to the shaft extender so it can not rotate freely. (I haven't quite worked that last bit out yet.)
(https://imageshack.com/a/img924/562/kz2xrr.jpg)
(https://imageshack.com/a/img921/1961/Z1NDt5.jpg)
Brian, what keeps the blue gear from sliding sideways towards the moving dog when the dog is disengaged? Seems like it could slip sideways on the red bearing?
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I set up the Kerzel engine this morning and ran it. My laser tachometer tells me it is turning at 960 rpm. This is twice as fast as I require, in order to get the saw to make 12 to 14 strokes every 10 seconds. I can not make the engine run any slower, so I will have to put one more set of gears in the drag-saw gear train. I currently have a 5.4:1 ratio in the gears on the saw, so I will have to install a second set of gears at 2:1 ratio to give an engine speed of about 900 rpm.
https://www.youtube.com/watch?v=5Y5VTDfrIRg
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This first bit is a head scratcher. Where do I start?--well, the green colored part is the available shaft end and flywheel hub on the side of the Kerzel opposite from the governor weights. It is 3/8" diameter x 1.125" long. The brown colored part is a steel shaft extender 3/8" i.d. x 7/16" o.d. that slides over the Kerzel shaft and is pinned there by a 3/32" diameter cross pin. (And maybe some Loctite). The dark blue gear is a 24 dp x 20 tooth gear which has an internal bore of 1/2" and has a bronze bushing (red color) pressed into it. It also has three "dogs" machined on one side. It actually "floats" on the shaft extender and is not keyed to it in any way. There is a shoulder on the end of the brown shaft extender which the gear rides up against. The pink part is a steel sliding bushing with three "dogs" machined on it that will fit into the three slots between the dogs on the blue gear. It has a "groove" machined into the outer diameter, which a pair of pins on the shift lever fit into. It is capable of sliding along the shaft extender, and is also keyed to the shaft extender so it can not rotate freely. (I haven't quite worked that last bit out yet.)
(https://imageshack.com/a/img924/562/kz2xrr.jpg)
(https://imageshack.com/a/img921/1961/Z1NDt5.jpg)
Brian, what keeps the blue gear from sliding sideways towards the moving dog when the dog is disengaged? Seems like it could slip sideways on the red bearing?
Nothing at the moment. Will have to figure out a retainer.---Brian
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Crueby--will probably put a 1/16" pin thru one of the dogs in the blue gear that fits into a shallow round slot in the shaft extender it runs on. that lets the gear rotate freely but stops it from sliding away from the shoulder it rides against.
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I've spent 6 hours today in "geometry world", coming up with a set of linkages that will work for the drag saw. I know of no set of equations that will let you calculate this stuff. It is more "try it and see" engineering. What I have here is a set of linkages that go through all of the required motions without binding or going into a "lock" position. Now I have to take the time to do a visual comparison between what I have and what a real drag-saw looks like. This is fun stuff, but it isn't easy. Before I cut any metal, I will build these linkages full scale in cardboard and using "stick pins" work it through all of the required motions.
(https://imageshack.com/a/img921/2360/Z7OAvc.jpg)
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Brian now that you have added the second shaft it may be easier to have the dog clutch on the sproket end of your lay shaft. That way the pinion gear can fit onto the existing engines crank without the need for extending it and the slower speed will mean less crunching when you engage the clutch plus you have an untouched shaft to start with.
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I am having second thoughts about using the Kerzel engine with the drag saw. The Kerzel has a 3/4" bore, while the Odds and Ends engine has a 1" bore, larger flywheels, and is all around a bigger engine. I'm looking at the size of the Kerzel compared to the larger Odds and Ends hit and miss engine and I think the Odds and Ends engine would be a better choice.
(https://imageshack.com/a/img922/6261/YiN5vU.jpg)
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Jason--You are right, but there are too many things rotating around the face of the disc on the second shaft to give me room there for a dog clutch.
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Brian I mean the lay shaft with the large gear/small chain sproket which has nothing in the way
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Here's one I made earlier.
https://www.youtube.com/watch?v=FaBTscGnkjY
Robert
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Beautiful display Robert!
Gbritnell
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Beautiful Robert!! That must get a lot of attention at shows.
Bill
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Hi Robert,
Stunning display.
John
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Robert--Lovely job. I can't see clearly--the rope that lifts the saw goes over a pulley block on top of the mast, and I can't see where it goes from there. Does it go back down to a winch system? --Brian
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That is very cool, Robert!
Love having the boiler, engine and saw all on the same display. And the little row of cut-off disks showing the work of the saw is great!
Kim
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Okay--Got that sorted. The engine is now the Philip Duclos "Odds and Ends" hit and miss engine. In order to get from 1000 rpm at the crankshaft to 84 rpm at the disc which the saw arm attaches, and to fit the constraints of what I have, there are actually two gear reductions coming off the engine shaft and one roller chain reduction. Part of the reason there are two gear reductions is to get the disc spinning the same clockwise rotation of the engine, and to get that large 108 tooth pulley with the spokes far enough away from the engine crankshaft to enable getting a cross shaft underneath the engine to reach the far side of the engine where the chain and sprockets will be. I haven't changed anything on the drive disc and linkages which are shown.
(https://imageshack.com/a/img924/4002/wVooBx.jpg)
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Looks great Brian, this will be a fun project to follow.
Have a great day,
Thomas
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That small yellow gear won't do anything in the way of reduction, it's just acting as an idler, could be any size you like and won't affect the ratios.
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That small yellow gear won't do anything in the way of reduction, it's just acting as an idler, could be any size you like and won't affect the ratios.
I'm not sure you are right. The smallest gear is a 20 tooth on the crankshaft. The yellow gear directly below it is a 30 tooth. When the crankshaft gear does one revolution, the yellow gear will only make 0.666 revolutions. The 108 tooth gear below the 30 tooth yellow gear will only turn 0.2777 turns when the yellow gear revolves once. so--Total reduction from crank gear to 108 tooth gear is 5.4:1.
when the 108 tooth gear rotates once, the crankshaft will rotate 5.4 times.
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Hi Brian.
Jason is quite correct, that gear is purely an idler. In fact on early " high class " engines they made the intermediate gear with an odd tooth number, this reduced the wear in one place as each valve was lifted.
That intermediate wheel simply reverses the rotation between primary and secondary wheels, one tooth in one tooth out.
Cheers Graham.
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Brian, just look back at your earler post or do the maths again 108/20 also equals 5.4
http://www.modelenginemaker.com/index.php/topic,8396.msg181692.html#msg181692
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I pulled the flywheel off of the starter side of the Odds and Ends hit and miss engine. It appears that I will be able to make my dog clutch work on this side and still be able to use my electric drill starter. I am proceeding with more layout work on the drag saw mechanism and frame.
(https://imageshack.com/a/img922/827/hKctTk.jpg)
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Yes Jason--You were right. I thought there might be something a bit fishy about what I was saying, although it sounded good to me ---at first.---Brian
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Just love the display Robert, all together like that shows the complete system, especially if you wish to explain it to someone at a show/display. Maybe a newbie :shrug: :thinking: :cartwheel:
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This thing is going to be big!! I'm pretty sure I have all the calculations right. The log is 3" diameter which is fairly close "scale-wise". The keyhole saw I inherited from my father and haven't used in 20 years is going to provide the blade for this beast.
(https://imageshack.com/a/img921/2051/5aUmVq.jpg)
(https://imageshack.com/a/img921/9831/lWisj8.jpg)
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I'm along for the ride. :popcorn:
An engine is great. An engine doing work is really great.
Robert's model is certainly an inspiration.
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Brian
I can't see clearly--the rope that lifts the saw goes over a pulley block on top of the mast, and I can't see where it goes from there. Does it go back down to a winch system? --Brian
The "rope" attaches via a pulley block to the cross head guide. The end of the rope goes around the hand winch.
Robert
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Brian, as has been mentioned before you really want a blade that cuts on the PULL stroke and that pad saw won't unless you intend to cut it down and drill for fixings at the other end. If the blade sticks when it is pushed it will buckle but that won't happen when it is being pulled as it will be in tension. Small bow saw blade or a cut down Japanese saw or a tree pruning saw will do. These can be cut down and a hole added and will look the part.
https://www.dictum.com/en/japanese-saws-baaa/replacement-blade-for-akagashi-universal-270-kataba-universal-270-712986
That may also affect the direction you run in as the engine end of the saw wants to go downwards on the pull stroke.
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Jason--My intent was to cut this blade down and taper it in the other direction to what is shown. That way it will be cutting on the pull stroke. If that doesn't work (it's free) then I will buy the one in your link. Thank you.---Brian
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Someone said that a journey of 1000 miles begins with one step. The only thing on this drag saw that I haven't made before is the "dog clutch". So---that is where I will begin. The design is going to be marginally different from the one in the attached 3D model because of minor differences in the output shaft on the Odds and Ends engine from the Kerzel.
(https://imageshack.com/a/img924/792/k8CjJU.jpg)
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Today I machined the crankshaft extension for the Odds and Ends engine. There is more to this extension than meets the eye. It has two counterbores machined on the far end, one to precisely fit the flywheel hub, and one to match the 1/2" length of crankshaft that extended past the flywheel hub. The end you can't see is drilled and tapped six places to match the clearance holes in the flywheel. You can see that in the pulley I removed in order to fit the extension on. In a perfect world, there will be no wobble in the end of that shaft extension when the engine is running. The 20 tooth gear, bushing, and drive dog will all be fitted to this extension. I machined two grooves in the large outside diameter of the extension in case I want at some point to drive o-ring drive belts with this engine.
(https://imageshack.com/a/img922/2886/qaqKVO.jpg)
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Today has been mostly cad work, figuring out the overall layout, how part A connects to point B, etcetera. I still have to find room for a gas tank, as the one currently on the Odds and Ends engine will be in the way. I'm liking this. The log being sawed is 3" diameter.
(https://imageshack.com/a/img924/1616/aEWFSk.jpg)
(https://imageshack.com/a/img923/7408/X3d9Xk.jpg)
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This shows the dog clutch lever by itself and how it assembles to the drag saw, where it pivots on the axle. It moves very little to engage or disengage the dog clutch. Right now I'm not sure how to make it stay "in gear" or "disengaged". There isnt enough movement to use ball detents`. Maybe a couple of spring washers and a bolt through the bottom pivot?
(https://imageshack.com/a/img922/8963/ASjkT0.jpg)
(https://imageshack.com/a/img922/7231/GC0XT6.jpg)
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This morning I even found room for a gas tank. I also changed the two members that reach from the engine up to the log. I originally had them as 1/2" round rod, but all of the drag saw videos show them as being rectangular wood. I'm getting close to the point where I start cutting metal.
(https://imageshack.com/a/img923/4048/ZY5PYE.jpg)
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Today I finished most of the detail drawings and machined the gear half of the dog clutch. It may prove interesting to make the other half.
(https://imageshack.com/a/img922/4461/TBNbSR.jpg)
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Something in my black old heart tells me that both parts of the dog clutch should be hardened, then "drawn back" to a point where they are tough but not brittle. My heat treat capabilities are limited to oxy-acetylene torch and my wifes kitchen oven. I already had the gear, made from 1018 mild steel so can't heat treat it, but I am going to machine the drive dog tomorrow, and it just happens that I do have a piece of o1 material the right diameter. I will machine it to size, heat it to cherry red with my torch, then drop it into a container of oil. Then 2 hours in my good wifes kitchen oven at 350 degrees F for two hours.
(https://imageshack.com/a/img921/4138/kyFCJw.jpg)
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I've been watching. :popcorn:
A drag saw (not that I knew about them before) is a wonderful model of times past.
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:popcorn:
:ThumbsUp:
Very cool Brian.
John
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Brian, you could case harden the mild steel gear which will give a hard wear surface but the core will remain soft.
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Jason--I would like to do that, but I would have to send it out and have it done somewhere, as I have neither casenite nor a heat treat oven.----Brian
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I do it with my propane torch, your Oxy one would do it too. There are some home brew mixtures if you don't have the powder using things like leather and bone.
As you are only heating to red, dipping in the powder and then quenching the heating is no different to how you harden your O1 but as it needs no tempering afterwards you don't even need to bother the wife about using here oven
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Hark Hark--The dogs bark!!! Dog clutch is finished and will engage and disengage as I had hoped. A lot of fussy set-up, but turned out great. Pictures show it engaged and disengaged.
(https://imageshack.com/a/img922/4954/aLHAGi.jpg)
(https://imageshack.com/a/img921/2329/DGoLYN.jpg)
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All the gears that will be used in the drag-saw are finished. The largest and smallest were "repurposed" from the walking beam project. The center gear was just finished 15 minutes ago, and I'm done for the day. My back is killing me and I have to go across town and pick up some aluminum from my supplier.
(https://imageshack.com/a/img924/5107/VzvXbk.jpg)
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Interesting project Brian. :popcorn: :popcorn:
I've seen a few of these in full size. The model will be interesting.
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Hi Craig--I haven't seen one before either, only YouTube videos. I did see one at a steam show in Milton last weekend, but it was a different style than the one I'm making, and it wasn't operating. I have just about ran out of ideas for things to run with my engines, so I welcome a new project.---Brian
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This build has inspired me to finally go back and figure out how the valving works on the Ransome Tree Feller, which is a simaler setup to this but steam powered - had never been able to figure out the valving till now. At some point I will model it up in Fusion as a 3D model from the patent drawings (probably during some cold snowy week this winter).
For now, really enjoying this build!
:popcorn: :popcorn: :popcorn:
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Hi Chris--Thanks for your interest. I follow your thread every day. Now that I have the basics of the dog clutch finished and the gears cut, my next step will be to make the two plates which support the engine and the shaft for the gears. I want to start the engine and see how it handles the load of the gears alone, although I think it shouldn't have a problem.---Brian
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So far today, it has been "work like Hell and not accomplish much" kind of a day. I did drill and ream holes in a piece of scrap at the calculated gear centers, and all seems to be fine. Gears mesh with no binding. In the picture they are running in the mill with lots of oil on them. I will let them run for 15 minutes or so before tearing the set-up down. Now, I have a calculated number for the sprocket centers, and will test the chain and sprockets the same way, after I have shortened the chain to the appropriate number of links.
(https://imageshack.com/a/img924/2816/aOPjCu.jpg)
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My calculation for sprocket center distance seems to have been "right on". After a half hour struggle with the master link it all goes together and looks about right. Not under tension but not a lot of slack either. The uglies on the face of that large sprocket are a testament to just how bad my vision is getting for welding things. A little J.B. Weld will fill those cavities. I buy my sprockets as "flat" sprockets with no center hub. I make up my own center hubs and weld them in.
(https://imageshack.com/a/img923/8927/W1gj7f.jpg)
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Progress is being made. This morning I finished the 1/2" thick engine sub-base which connects the engine to the rest of the components underneath, and gives me an alternate place to mount a gas tank. The original gas tank on this engine was mounted to the side where you see the two socket head cap screws, and would have been in the way. The next plate I make, which is going to provide a place for the 108 tooth gear shaft and the 30 tooth gear is going to be a challenge.
(https://imageshack.com/a/img924/4955/iFiSe4.jpg)
(https://imageshack.com/a/img924/1971/1ZqdOK.jpg)
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Going to be cutting something other than metal pretty soon. :ThumbsUp:
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Looking good Brian. You may want to allow turning the rear wheels 90 deg. Though, it seems like the saw may want to pull itself up & over the log like a rack & pinion.
John
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The complex endplate is roughed in using the bandsaw, and tomorrow will be milled to finished size. That 1 1/2" hole bored in the center is cosmetic, nothing more. The large sprocket with the shabby welding showing on the one face was treated to some J.B. weld, left overnight to harden up, then painted with a rattle can. A little paint hides a lot of sin!!
(https://imageshack.com/a/img922/4249/S3JNtD.jpg)
(https://imageshack.com/a/img924/4378/yysiXF.jpg)
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:popcorn: :popcorn: :popcorn:
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That went very well!! The riser plate is finished and installed. The gears all mesh perfectly. I have a couple of shafts to shorten, but all in all I'm happy with the way that turned out.
(https://imageshack.com/a/img922/6170/aOPpcC.jpg)
(https://imageshack.com/a/img923/239/M6ZesX.jpg)
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This morning I completed the other riser block, which serves as the bushing holder for the large sprocket shaft and also gives a place to bolt the two long rectangular "handles" to. I have removed the engine from the drag saw platform to make some adjustments to it before reassembly. The chain fits as I had intended, with no last minute surprises. While I was boring this last piece in the lathe, I managed to turn out the tailstock spindle too far and it all came apart, so now before I do any more work, I have to figure out how that goes back together.
(https://imageshack.com/a/img921/7483/exQ4yj.jpg)
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Today is a milestone in the drag saw build. I wanted to be certain that the Odds and Ends hit and miss engine had sufficient power to cope with the gear train of the drag saw. It handles it with no difficulty, which is great. Now I can proceed with the rest of the build.
https://www.youtube.com/watch?v=r5A2P8KrjSg (https://www.youtube.com/watch?v=r5A2P8KrjSg)
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Nothing real exciting machined today. Just an axle. The real, full sized drag saws had short stub axles, each attached to a pivot so the machine could be dragged along using the handles, or the wheels could be turned at 90 degrees to help prevent the drag saw platform and engine from moving as the saw cut through the log. Obviously, I'm not going to do that with mine. Mine will have the handles pinned to the log to prevent the platform and engine from moving as the saw cuts. If you look closely, you can see the 3/16" hole thru the right hand end of the axle where my dog clutch arm will pivot.
(https://imageshack.com/a/img924/1682/kD1Bd3.jpg)
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Hello Brian,
Your project is coming along really good. Went to youtube and watched your last video and it sure looks nice with all the parts in action. Great build.
Have a great day,
Thomas
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Thanks for having a look at the video and for saying Hi. I'm not getting a lot of spectator comments on this build, but maybe it's so "far out there" that either people aren't interested or they are waiting to see if it actually runs and saws logs.---Brian
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We are definitely here and watching!
:popcorn: :popcorn: :popcorn:
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We are definitely here and watching!
:popcorn: :popcorn: :popcorn:
For sure :ThumbsUp:
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Some of us have to saw logs once in a while ;D
I've been following. :popcorn:
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Hi Brian, I am also following along with interest. I am sure it will cut logs, and projects that make an engine do some work are always interesting.
MJM460
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I've got a little mystery to solve here. The engine runs at 1000 rpm. I have an overall gear ratio of 12:1. That means the piece of tape should be turning 1000/12=83.3 rpm, which equals 13.9 times per 10 second interval. I just had my son count of 10 seconds on his cell phone/stop-watch, and it looks like the tape is going about 20 complete turns per 10 second interval.--Which would mean 120 rpm, which multiplied by 12 gives an engine rpm of 1440 rpm. Check the video and tell me how many revolutions that piece of tape makes in a 10 second interval.---Brian
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Hello brain,
I'll let you know that I'm following you. Looks promising already.
On the basis of your video that you uploaded yesterday. I did have counted 114 rotations per minute. I played the youtube video with a speed of 0.25. I did count 57 rotations over 30 seconds time. So that's pretty close to what you measured (20 rotations per 10 seconds).
On the basis of this you would reach a motor speed of order size 1360 with a ratio of 12: 1.
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Can't you just put your tacho on it again?
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And there gentlemen, you have the long and short of it.--mostly the long. I knew right from the beginning that this was going to be a lengthy beast, and this just confirms it. The notches in the underside of the rails, out at the end opposite the engine, is for a cross-beam that bolts on and can be "pinned" to the log to keep the main saw body from dancing all over the place during a cut. The notch in the top side is for a beam with an adjustable stop on it that prevents the saw blade from trying to dig a hole thru to China after it has passed thru the log.
(https://imageshack.com/a/img923/3439/eihJ6G.jpg)
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Jason---It isn't a huge problem. That sought after 14 strokes in a 10 second time interval was based on me sawing a pine 2 x 4 with a handsaw. It probably won't hurt is the saw runs a bit faster. I have lots of room on the roller chain side to put on a larger sprocket to bring the speed lower if I need to. Thank you for confirming my count.--Brian
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So--We're getting right down to the "short steps" of this monster. Today I made and installed the two cross-members that fit between the frame rails, the brass "Handgrips" at the end of the arms, and the 4" diameter wheels. I still have to make an arm to control the dog clutch, and all of the parallelogram links in the saw mechanism. I went and looked at saws today, and nothing really appealed to me. Then I called a saw sharpening service here in town, and they charge $10 to sharpen a saw and $4 extra if they have to "set" the teeth. I have about 4 or 5 handsaws that I inherited from my father---They are all dull. I made an appointment to see the saw sharpener tomorrow and I will take my collection of handsaws over to him and explain what I am doing and have him sharpen one of the existing cross-cut saws to use on this project. I may use the keyhole saw I showed earlier in this thread. The only part of the entire machine that motivates the saw to cut thru the log is the weight of the saw blade and the parallelogram arms, responding to gravity. The arms will all be made from steel.
(https://imageshack.com/a/img923/1797/cxKk6D.jpg)
(https://imageshack.com/a/img921/3502/Q1ebXk.jpg)
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Great progress, looking forward to seeing it go!
:popcorn: :popcorn: :popcorn:
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Looking great!
I do wonder about those rear wheels. I think someone else asked...are you going to modify so they can pivot 90 degrees?
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I went over this morning and took three of my dad's hand-saws to the saw sharpener guy. I explained to him what I was making, and asked which of the saws would have the best tooth profile for the drag saw. He had a look at them and said that none of them had been sharpened correctly in the past, and there wasn't a lot he could do to sharpen them. Then he went over to a rack of used saws that he had sharpened and no-one had picked up, and he gave me one, newly sharpened, with the correct tooth profile. I gave him two of dads old saws in return, because I've had them over twenty five years and never used them. I am currently working on the parallelogram links to mount the saw blade.
(https://imageshack.com/a/img924/3485/UGtz54.jpg)
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Looking great!
I do wonder about those rear wheels. I think someone else asked...are you going to modify so they can pivot 90 degrees?
No Zee, I'm not going to make the rear wheels so they swivel 90 degrees. The cross-member farthest from the engine gets "pinned" to the log, and that will keep the saw rig from moving.
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Are you not going for the usual chain on a drum with simple ratchet to hold it to the log?
The wheels swung more to make it easy to move along the log than stop it moving during the cut
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Today was one of those days when I spent more time figuring out how to make some of the parts than I did making the parts. The first three parallelogram arms are semi finished and shown in place.
(https://imageshack.com/a/img922/2320/gkp8ry.jpg)
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Are you not going for the usual chain on a drum with simple ratchet to hold it to the log?
The wheels swung more to make it easy to move along the log than stop it moving during the cut
Not right now. Maybe after I see if it actually works.
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Looking good Brian :popcorn:
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Hi Brian,
It looks bigger every time you post new photos, looking real good.
Have a great day,
Thomas
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Brian
I continue to watch your great progress. I was displaying my models at county fair and my friend, Bud, had his Witte running. It is the one you showed in the first post. He had not had it out in awhile and the clutch pad was soaked with oil. He had made a new one and was trying to get it adjusted when I took some photos. If I had been there 30 minutes earlier he had the friction clutch all apart. From my photo all you can see is the leather sticking out of the clutch plate.
Looking forward to log cutting.
Bob
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Bob--I wish I could see a real one like that, running. I have only ever seen videos of drag saws.---Brian
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It doesn't look like much, but I have a full days work in these parallelogram arms. Each arm has oilite bronze bushings at the pivot points. The actual pivot pins are 3/8" shoulder bolts. I got very lucky and discovered that one of my slitting saws was the same width as the saw blade I plan on using, so the bottom link is slit and ready to accept the saw blade. Tomorrow I will possibly make the crank arm and the connecting link. I was a bit concerned about there being sufficient weight in the arm assemblies to force the saw into the cut, but now that I have the arms almost finished I see that there will be sufficient weight.
(https://imageshack.com/a/img922/2750/qsfcLm.jpg)
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Check out this video of a drag saw with parallelogram action, same as the model I am building. Notice that the wheels are NOT turned at 90 degrees, but are positioned the same as the wheels on my model.---Brian
https://www.youtube.com/watch?v=MTG4jku86bM
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Hi Brian,
Looking good! The video brings it all together. I see that the saw has a “post arrangement” down against the log on the saw side & chain & hook on the outer side of the log to stop it moving to much. As a suggestion & I’m not sure this is going to make sense but have you thought about a couple of fold down arms on the outer end of the 2 main arms that lock against the main arms when in the down position? I have fold up foot boards on my trolley that is used behind my loco’s, an L shaped bracket gets the pivot point out & the face of the arm them pushes against the frame. Can supply a picture if this is totally unclear!
Cheers Kerrin
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As I say in the attached video, "We're almost ready to rock and roll." I need to cut out my saw blade and machine a lever to operate the clutch and then I think we will be ready to cut up a log.---Brian
https://www.youtube.com/watch?v=XCsBUj2Pfg0
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Looking forward to the results.
John
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And for those of you who asked "Where do you get a blade" and "You know those saws only cut on the pull stroke." Here is where you get the blade with the teeth cutting in the correct direction. About 10 minutes work with a die grinder and an abrasive wheel. I wrapped a piece of steel bar with a wet dish cloth and laid it over the part of the saw I wanted to keep so the heat wouldn't warp it. Now if I'm really lucky, I will be able to carbide two 1/8" diameter holes in it to bolt it on.
(https://imageshack.com/a/img923/2163/1AXHKs.jpg)
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Did you show that picture of the saw to the nieghbor you borrowed it from? :o
:popcorn:
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I may have to rename this thing the Pinnochio saw---
(https://imageshack.com/a/img921/6601/4MPZkh.jpg)
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Did you show that picture of the saw to the nieghbor you borrowed it from? :o
:popcorn:
No---When I explained to the saw sharpening service guy what I was building, he gave it to me--all sharpened up.
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I like your Pinnochio saw! That blade is just right for a model...
One last part to make..... the parking clamp for the blade.
:ThumbsUp: :popcorn:
Pete
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That last picture is great! I'm enjoying the build...it's given me some motivation.
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I have a laymans knowledge of handsaws. My dad was a carpenter when he wasn't lumberjacking, so I know the difference in a cross cut saw and a rip saw. I have a vague notion of what "raker teeth" do. My saw knowledge stops about there, and although I am aware of "pit saws" and "ice saws", I have no idea as to the tooth profile. I have never seen a "real live drag saw" other than a couple of weeks ago when I seen one that wasn't operating at a steam show in Milton Ontario, and it wasn't the type which I am building. You folks have no idea of how desperate I get to find something mechanical that I haven't already built. This has been a fun build, and I am in the home stretch now. I may even give this thing a test drive tomorrow, but only on a pine 2 x 4. I won't make a video until I can find a 3" diameter round of dry cedar or pine with the bark still on it. I still have to build the handle which engages and disengages the dog clutch, but that won't stop me from taking a test drive.
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I like your Pinnochio saw! That blade is just right for a model...
One last part to make..... the parking clamp for the blade.
:ThumbsUp: :popcorn:
Pete
Pete--Tell me more. I am not aware of a "parking clamp" anywhere.---Brian
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Hello Brian,
The saw looks really great and you have done a wonderful job on all the construction and design. Looking forward to a working video.
Have a great day,
Thomas
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Brian, in posts #91 & 94 the pics show a deeply slotted block. In the first pic the blade is halfway in to the block. The next pic shows the blade/block positions in use.
Those ol' boys sure knew what they wanted on the machine! I'd only seen a few of these saws until this thread was created. There's nothing like old iron...
Pete
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Actually to "park" the blade there is an arm that swings up and supports the linkage. When moving the saw about it needs to be held up so that it does not flop about, this picture shows it in use. It also shows how the wooden block rides up the angle bracket when the blade is raised. The wooden block only serves to guide th eblade at the start of the cut much like you would put your thumb against a handsaw to start it where you want, once the cut has started the saw blade will guide itself in the kerf it has created.
(https://i.ebayimg.com/images/g/bswAAOSwcUBYQzId/s-l1600.jpg)
As does this Video, maybe you want to add the felling rig too
https://www.youtube.com/watch?v=Np2jED0HB3M
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I am about to finish the final parts of this drag saw. If you have followed this post, you will know I am using a dog clutch which is engaged and disengaged by a lever. I have watched two dozen videos of drag saws on YouTube, and I'm still not certain of what type of clutch they used--it isn't clear in the videos. If anyone has detailed knowledge of how these original drag saw clutches operated, now would be a really good time to contact me and let me know. I have heard that they too have lever operated dog clutches, but I have also heard that they had friction clutches which gave them a gentler engagement than a dog clutch. If anyone has this knowledge, I would really appreciate a heads up.---Brian
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Jason--Thank you for that picture--I hadn't seen that before. Pete--That thing you are talking about is a saw guide to ensure that the saw starts cutting where you want it to.
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Hi Brian,
Enjoying your Drag Saw build, friction clutch for full size Drag Saw here may give food for thought. Mike.
http://www.herculesengines.com/hercules/NewManual/page_58.html (http://www.herculesengines.com/hercules/NewManual/page_58.html)
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Today I finished the dog clutch engagement lever. I realized that I had no way to put in the fancy scallops on each side that are shown in the cad model, because the handle is too long to swing on my lathe faceplate. If I can make it work properly, I may drill a series of cosmetic holes down the face below the hole that fits over the clutch diameter. Right now it works fine as far as engaging g/disengaging the dog clutch goes while the engine is not running, but there is nothing to make it stay engaged or disengaged. I have been warned that it is difficult to disengage the dog clutch while the engine is running. If that is true, perhaps I can just install a light spring that makes the lever disengage when no other forces are applied to it.
(https://imageshack.com/a/img921/6486/mOGgUY.jpg)
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Hi Brian,
Enjoying your Drag Saw build, friction clutch for full size Drag Saw here may give food for thought. Mike.
http://www.herculesengines.com/hercules/NewManual/page_58.html (http://www.herculesengines.com/hercules/NewManual/page_58.html)
Mike--Thank you. That is exactly what I was looking for.---Brian
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So--We have confirmation that everything goes round and round and up and down when the saw is operating but not actually cutting anything. Next step will be for me to tramp around in the woods behind my place and find a real 3" diameter log to cut.
https://www.youtube.com/watch?v=bzR7VE02jeo (https://www.youtube.com/watch?v=bzR7VE02jeo)
(https://imageshack.com/a/img923/6058/jR4NzT.jpg)
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So--Today the drag saw cut it's first log. Everything went very well, except that I need to get a more aggressive blade. About half way thru the log, the saw seemed to take forever until I gave it a bit of extra weight from my thumb. A picture taken after the cut shows that there were two knots hidden away in the center of the log. Everything works as I hoped it would. My dog clutch worked as I had hoped. (I never made one of them before). I will post another video after I get a more aggressive blade and put a spring on my dog clutch lever to keep it from rattling. I sell a complete set of drawings for this drag saw for $25 Canadian, but that does not include the engine.
https://www.youtube.com/watch?v=ylLgquXJfhQ (https://www.youtube.com/watch?v=ylLgquXJfhQ)
(https://imageshack.com/a/img922/8669/FkVMed.jpg)
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hey Brian,
Watched both videos and your machine is just fantastic. A blade with a bit more aggress teeth would surely cut a log faster. Beautiful job.
Have a great day,
Thomas
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Fantastic!
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That is pretty cool, Brian! Fun video :ThumbsUp:
Kim
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I just went downtown and spent $12 of the Rupnow fortune on a saw with a really radical tooth profile on one side. Tomorrow we will see about mounting it on the drag saw. I did find out something today. Saws that have a handle which spans both ends of the blade are only .024" thick. Saws that have a handle at only one end are .036" thick.
(https://imageshack.com/a/img924/6016/JG1vFt.jpg)
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That tooth profile looks much more like a log saw, should work much better.
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Nice job! :ThumbsUp: Cut the log quite smooth.
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Brian
Really looking good, nice cut. Do not get rid of the slow cutting saw. As I mentioned in another thread my friend Jim ran one of these at shows. He would have it running for days at a time. Would run out of logs, and continually moving the saw and locking it got to be a bit of a pain. Now it was fun to watch it cut off a log but after three or four days at a show it became work. The solution was a dull blade so all the action was there and everyone could see it cut away. He used a band saw at home to cut lots of cutoffs ( to give to the spectators). He would lay four or five around the end of the log. When someone wanted one he gave it to them. Running all day maybe only cut 3 or 4 actual pieces. More fun less work, could spend time answering endless number of questions about the models.
So from experience, keep that slow blade.
Bob
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Bob--You're giving advice on keeping things to a man that never throws anything away. If the new blade cuts better, the old blade will hang on a nail in my garage into the next millennium. :Lol: :Lol: I've enjoyed this build, and it has went relatively quickly.---Brian
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Works a treat! Congratulations Brian!
Great work,
John
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Very nice Brian. Will be interesting to see what the more agressive blade does. Great project!!
Bill
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Hi Brian, nice project and congratulations for the first cuts.
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I installed the new saw blade, drilled a few cosmetic holes in the dog clutch handle, and put a very weak tension spring on the dog clutch handle to keep it disengaged. When it is engaged and the saw is moving, it seems to stay engaged without much of a problem, although I can disengage it quite easily by moving the lever. Even with the new aggressive sawblade, this thing is no speed demon at getting thru a log. When you've been used to chainsaws all your life, this thing cuts pretty damned slow by comparison, but 100 years ago it certainly would have seemed like a marvel to two men on a manual crosscut saw. The batteries for my camera are charging right now, so I might get the final video up before the day is over.
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This will be my final video of the drag saw, and I am deeming it a success. It cuts logs the way it is supposed to, and the engine has ample power.
https://www.youtube.com/watch?v=l3ypmkh12M4
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Good interesting project Brian with a successful ending :ThumbsUp:
Stew
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Excellent!!
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:ThumbsUp: Nicely done Brian!
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Thank you guys. So--an interesting comparison. In the first video, using a newly sharpened carpenters saw, the saw took 7.2 minutes to cut thru the log. In the last video, with a much coarser style of saw profile, the saw took 3.2 minutes to cut thru the log. That is more than twice as fast.
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Nicely contrived, Brian. It was a fun journey following along.
Regards,
Rudy
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That new blade eats right through that log. :ThumbsUp:
Have a great day,
Thomas
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Just wonderful Brian; do MEM members get a discount on the plans?
Whiskey
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Nicely done Brian!
Dave
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Just wonderful Brian; do MEM members get a discount on the plans?
Whiskey
That is my discounted price. Designed, detailed, built, de-bugged, and operational.
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Just wonderful Brian; do MEM members get a discount on the plans?
Whiskey
By the time Brian has paid out all those who have helped him with info during the build there won't be much left for him if he discounts it any more :LittleDevil:
I think the two knots had more effect on the time it took to cut the first log than the blade, looking at the videos they both take about 30secs to get to the same point where the knots start. I wonder if the linkages were made from steel rather than aluminium if you would get a better cut as there would be more weight on the saw blade though that may start to bog down the engine.
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Jason--You may have missed it in an earlier post.--all of the saw links are made of steel. If they were aluminum, the saw wouldn't feed at all. The knots definitely had an effect on the cut in the first video. The saw is not bogging down at all, so I could safely add weight to the mechanism. The problem is that when I start adding weight anywhere, it looks less and less like the original dragsaw it was patterned after.
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Great project and result Brian, I might be way off the mark here but could the log be set too low? It looked at the end like the blade was being pushed down into the log, shouldn’t the angle mean it is pulling down into it on the back stroke? Anyway, it worked well and I think the blade you used can cut on front and back stroke?
Sent from my iPhone using Tapatalk
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Nick--It's all in the position of the pivots and the lengths of the arms. When the saw blade is held up by the log it takes on a totally different path as it strokes than when the main overhead arm is held up by a bolt underneath it to prevent from the saw cutting too deeply and plowing into the ground at the end of the cut. When the saw is setting more or less level on top of the log, it maintains that level, but as the saw drops thru the log the saw takes on more and more of a tilt in the swing as it gets lower and lower. There is a "range" of where the saw stays level, but above or below that rang, the saw tilts more and more.
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Nice Brian. I've seen a few of these in operation and your model really mimmicks the "real thing". :ThumbsUp:
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Love watching these at engine shows - another great job !