Model Engine Maker

Help! => Hints, Tips & Tricks => Topic started by: Brian Rupnow on September 19, 2018, 08:45:58 PM

Title: How does this clutch work?
Post by: Brian Rupnow on September 19, 2018, 08:45:58 PM
After building the dog clutch for the drag saw, I asked for any friction clutch plans that people could find. Mike sent me this link. It looks like something I could use/build, but I can't tell how it works. It seems that the arm, part #A227 moves the slider, #A225 ahead and forces the comma shaped pieces #A223 apart. I assume that once the part #A225 is captured by these arms #A223, it will stay in place. Somehow the pressure of the spring #A238 must be involved here, to make the arms #A223 spring loaded to hold the expander cone part #A225 in place. There is a very faint dashed outline that shows these comma shaped parts #A223 in the position they would have if the slider cone A225 was not engaged. The only way I can figure a clutching action here is if there were gear teeth in the comma shaped part and a rack style series of annular grooves in the shaft it slides on, forcing everything to the right to put pressure on the friction disc #A189.  Maybe I'm overthinking this. Any other explanation of how this works will be gladly listened to.---Brian
http://www.herculesengines.com/hercules/NewManual/page_58.html
Title: Re: How does this clutch work?
Post by: Doc on September 19, 2018, 09:11:57 PM
Looks to be the same clutch as on old garden tractors. Pull the handle in and it pushes the clutch faces together and spins the outer shaft.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 19, 2018, 09:54:38 PM
I've been studying on this thing, and I think I have it figured out. I'll have to make a model to confirm what I think. It seems that the secret to this mechanism is all in the spring and the comma shaped pieces. When those comma shaped pieces are forced outward by the expander cone, they not only trap the expander cone but a tit on the bottom of the comma shaped piece makes the whole stack up of parts become marginally longer--enough to put pressure on the friction disc. Of course the magic in this isn't in engaging the clutch--it's in also capturing the handle so it can't slip out of engagement.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 20, 2018, 01:31:16 AM
Okay--Burned a few brain cells on this one. The clutch which I posted a link to in post #1 is not an "over center" clutch. It does however, not only engage and disengage the clutch thru pressure on the friction material, but also traps the handle so it won't jump out of engagement. This is a very clever design, and I had to study it a lot to see what was really happening. I have modelled it in both engaged and disengaged positions. EDIT EDIT--I have updated these drawings based on information from Velocette.
(https://imageshack.com/a/img922/8536/mGp0ry.jpg)
(https://imageshack.com/a/img921/4985/5uMXlg.jpg)
Title: Re: How does this clutch work?
Post by: 10KPete on September 20, 2018, 03:16:32 AM
Beautiful drawings, Brian. And a lingering question answered!

Pete
Title: Re: How does this clutch work?
Post by: dieselpilot on September 20, 2018, 02:03:04 PM
This is essentially the same mechanism for most collet lever drawbars. Simple cam action.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 20, 2018, 03:58:33 PM
I think this is an ingenious design for a clutch. The only issue with it that I see is that while it may be great for 1" diameter shafts and larger, it would be incredibly difficult to miniaturize it to work on a 3/8" shaft like most of my engines have. True, most of the components are simply "turnings" that would present no difficulty to miniaturize, but the comma shaped pieces would get so small I don't think I could machine them accurately. Too bad, because it is a really slick design.
Title: Re: How does this clutch work?
Post by: dieselpilot on September 20, 2018, 07:13:55 PM
The shape of the cam can be simplified. Only the contact points are functional.
Title: Re: How does this clutch work?
Post by: Doc on September 20, 2018, 08:24:06 PM
This is essentially the same mechanism for most collet lever drawbars. Simple cam action.
Yes this mechanism is used in many things.
Title: Re: How does this clutch work?
Post by: BillTodd on September 20, 2018, 09:13:00 PM
This  is an animation of the clutch pusher on a Churchill Cub lathe :
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 20, 2018, 10:18:54 PM
One of the nifty things about my software is that I can shrink or grow a part by whatever factor I want to. Since my model to develop the drawings from had a 1" diameter shaft, and my engines 3/8" shafts are roughly 33% of 1", I shrunk the comma shaped pieces by that factor to see what they would be like to machine. I don't think I could machine this repeatedly 3 times to have three comma shaped pieces 120 degrees apart.
(https://imageshack.com/a/img922/8509/rAkPRd.jpg)
Title: Re: How does this clutch work?
Post by: Admiral_dk on September 21, 2018, 11:21:39 AM
I will not in any way claim that I can make the part ….. But I would not start on 3 separate pieces - I would make one wide enough to cut 3 identical parts from with a slitting saw.

I'm not going to claim that this will make it easy, as even 3 identical "comma's" isn't a warrant for a working clutch - you need to get the slots and holes for the pins that hold them in place perfect too ….

I will certainly follow this closely if you should decide to have a go at it anyway Brian  :cheers:
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 03:10:06 PM
I suppose that if I were to get serious about making this part, the first step would be to rough it out as rectangular part  and drill the required holes as shown. You can see the shape it will become, and also the "first cut" of the metal. All of these cuts and holes can be made with great accuracy, using the DRO on my mill for positioning.
(https://imageshack.com/a/img923/9918/pSx6FF.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 03:20:10 PM
In second stage of machining all of the grey area would be milled away--again with a good deal of accuracy using the mill DRO's.
(https://imageshack.com/a/img924/4125/P3WR1J.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 03:37:37 PM
Final filing would look like this. The filing buttons would let me hold very good accuracy on the round ends.  The rest would have to be "filed to the line". Maybe I could make these.  Since they would be made from 1/8" thick cold rolled steel plate I "might" be able to stick three pieces of plate together and do them all at once to ensure they were all exactly the same. I have heard of folks soft soldering plates like this together, then doing all the machining, then reheating them to separate them. I have never done this and don't know how difficult it would be.
(https://imageshack.com/a/img924/3449/WBsITo.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 03:40:53 PM
Non of my slitting saws are large enough to cut these apart if they were all machined on a single piece of stock.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 03:59:16 PM
Might be simpler if I welded all three plates together first on the non critical side.--Then machine that area of plate and the weld off as my last step to leave me with three identical plates.
(https://imageshack.com/a/img921/6339/KuWNze.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 04:22:11 PM
Since these parts see the most wear as the clutch engages and disengages, I would make them out of 01 material, flame harden and quench, then draw them back to a stage of non brittleness in my kitchen oven for two hours at 350 degrees. 01 material is a bit harder to machine in its unhardened state than mild steel, but only a bit. It can be worked with HSS tooling.
Title: Re: How does this clutch work?
Post by: Alan Haisley on September 21, 2018, 05:52:17 PM
I think this is an ingenious design for a clutch. The only issue with it that I see is that while it may be great for 1" diameter shafts and larger, it would be incredibly difficult to miniaturize it to work on a 3/8" shaft like most of my engines have. True, most of the components are simply "turnings" that would present no difficulty to miniaturize, but the comma shaped pieces would get so small I don't think I could machine them accurately. Too bad, because it is a really slick design.
You're amazing, Brian  :)
First you decide that something is too hard for you to do and then you go ahead and figure out how to do it anyway.  :praise2:
If you are going to build this clutch I certainly want to look over your shoulder while you do it.
Alan
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 06:55:33 PM
Alan--It's okay---I'm going a bit mad these days. I don't have any real design work, I'm waiting for all my authors to publish something new so I'll have a good book to read. My yard-work is all caught up, and I'm too old to drink whiskey or chase women. I did have the only other model engineer in Barrie over for a couple of hours this morning and we sat and talked machinery and told lies to each other for a while but he's gone home now. I may build this clutch, #1-Just to see if I can, and #2-to give me something to do other than watch the idiot box.---Brian
Title: Re: How does this clutch work?
Post by: crueby on September 21, 2018, 07:32:19 PM
Alan--It's okay---I'm going a bit mad these days. I don't have any real design work, I'm waiting for all my authors to publish something new so I'll have a good book to read. My yard-work is all caught up, and I'm too old to drink whiskey or chase women. I did have the only other model engineer in Barrie over for a couple of hours this morning and we sat and talked machinery and told lies to each other for a while but he's gone home now. I may build this clutch, #1-Just to see if I can, and #2-to give me something to do other than watch the idiot box.---Brian
Brian, perhaps you may need a large model project, a vehicle or construction machine - great variety of parts, and many of them, something to keep you busy over a longer time. Lots of plan books (Kozo, etc) for locos and other types, maybe an early style Formula 1 or Indy style car...
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 08:58:23 PM
I decided that shrinking the clutch to 1/3 of it's original size was just going to make components too small, so I just spent a couple of hours shrinking everything to 1/2 size. In the large version it is configured for a 1" diameter shaft. In the small version it is configured for a 1/2" diameter shaft.
This brings it into a more "doable" size range.
(https://imageshack.com/a/img923/1341/Y3nob9.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 21, 2018, 09:01:01 PM
Chris--If I ever did what you advise, I would work myself right to death trying to finish it. I get so "into" whatever I am making, I find it hard to take time out to eat or sleep. I like these smaller projects that have a 30 day timeline.
Title: Re: How does this clutch work?
Post by: BillTodd on September 22, 2018, 12:19:31 AM
I don't think you need the :over centre' locking mechanism Brian .

Unless your clutch friction material is very compliant, and able to provide the traction pressure itself , the clutch will lack grip when over the peak . The collet closer on my hardinge uses pretty much the same finger lever as your design but has a flat after the expanding section , so once the closing force reaches maximum it stays at that level with the lever held in place by the friction of the fingers on thr flat section only.

Bill
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 22, 2018, 01:08:42 AM
Bill--You could be right---but---Open the link in the very first post of this thread and see what they did. I probably have the reduced diameter of the expander cone too exaggerated. I'll take a closer look at that in the morning.
Title: Re: How does this clutch work?
Post by: john mills on September 22, 2018, 10:08:03 AM
what does the spring do   does it not give some compressibility and give to control pressure on the clutch facing?
Title: Re: How does this clutch work?
Post by: dieselpilot on September 22, 2018, 12:32:00 PM
what does the spring do   does it not give some compressibility and give to control pressure on the clutch facing?

This is exactly the purpose of the spring in this case. Adjustment described in the text controls engagement point, so to change pressure you'd really have to change spring rate assuming the cam and cone are fixed.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 22, 2018, 04:07:51 PM
In about two minutes I am going to jump up and grab a piece of mild steel and make this expander cone. It's cold outside and good wife and visiting daughter are off to the mall. I don't have any 01 stock this large in diameter, so I'm not going to harden it.
(https://imageshack.com/a/img923/7830/YPFBEt.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 22, 2018, 06:18:26 PM
First part made---the expander hub. I made it from a scrap end of material that I had left over from something.
(https://imageshack.com/a/img923/2104/TWrtcx.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 23, 2018, 12:06:31 AM
I was originally going to make this clutch with three comma shaped arms. However, looking at the slitting saws I have, I decided to make it with four comma shape arms. This way I can cut the 1/8" wide slots in the blue hub all the way across the face.
(https://imageshack.com/a/img924/6007/jSKx0D.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 24, 2018, 12:01:43 AM
I don't post very many set up shots anymore, but this is a worthy one. No, it's not a Maltese cross, it's the hub that will hold the four comma shaped arms. There is more work yet to be done on it.
(https://imageshack.com/a/img922/3082/za2OwH.jpg)
Title: Re: How does this clutch work?
Post by: crueby on September 24, 2018, 02:34:57 AM
 :popcorn: :popcorn: :popcorn:
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 24, 2018, 05:12:51 PM
Now, is that a beautiful thing or is that a beautiful thing? I chickened out at the very last moment and put the slots in with a 1/8" carbide endmill instead of using my slitting saw. This part is steel and I didn't want to take a years life off my slitting saw. I took 0.010" deep cuts with the mill running at 1300 rpm and hand cranked very cautiously so as not to snap the endmill off.
(https://imageshack.com/a/img921/5965/DyHfxS.jpg)
Title: Re: How does this clutch work?
Post by: Ye-Ole Steam Dude on September 24, 2018, 05:17:17 PM
That is beautiful work Brian.

Have a great day,
Thomas
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 24, 2018, 05:19:08 PM
Now it's my turn to ask a question. What can I buy for a friction disc. The disc stands alone and is not attached to anything, simply centered on the shaft. In a perfect world, I would like something about 1/16" to 1/8" thick. Whatever it is, it has to not only have very good friction surfaces on it, but must be durable and capable of holding it's shape. It needs to be 2 1/4" diameter. If I don't get a good answer to this question, I may default to a piece of 1/4" plywood for a friction disc.
Title: Re: How does this clutch work?
Post by: Vixen on September 24, 2018, 05:39:46 PM
Hi Brian,

A plywood friction disc would be a good choice, especially if you can win some aircraft grade spruce ply. My old 1932 MG had multiple ply inserts in a steel disc for it's clutch plates, they were soaked in an oil bath, but did not slip.

Alternatively, you could try glass fiber printed circuit board, it's often pale green in colour, don't recommend the brown laminated paper/ resin stuff. Look out for some PCB with double sided copper. Either chemically etch or perhaps rip away the copper laminate. The exposed surface is rough with high friction. In the past, I have used it for the steering transmission for a 1/6 scale model tank

Mike
Title: Re: How does this clutch work?
Post by: gbritnell on September 24, 2018, 06:20:38 PM
Use a piece of leather. Available at most craft shops or on good old EBay. I save my old wallets for a good thin leather source.
gbritnell
Title: Re: How does this clutch work?
Post by: michaelr on September 24, 2018, 07:14:34 PM
Cork was one material that was used for clutch friction plates, may be still obtainable today.
Michaelr
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 24, 2018, 08:19:25 PM
I went down street on a shopping trip today, and bought a 3 foot length of 1" x 1/8" precision ground 01 steel to make the comma shaped pieces from. Also bought a couple of very healthy small springs, one of them will work on the end of the clutch shaft, not sure which yet. Also picked up a sprocket which can be bored out to fit the appropriate clutch hub. I sawed off four 1 1/2" long pieces of the 1 x 1/8" 01 material, lined up the sides and one end, and clamped them in a set of welding vice grips. I will put a dab of mig weld on the ends which will be trimmed away after the fact, so I can machine all four pieces at the same time to ensure that they are all the same.
(https://imageshack.com/a/img921/2240/b2OeCe.jpg)
Title: Re: How does this clutch work?
Post by: Tennessee Whiskey on September 24, 2018, 08:37:47 PM
+1 on the leather

Whiskey
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 01:09:09 AM
I'm curious--those of you who have suggested leather, how would you use it. Would you glue it to the face of one of the discs, or just let it free float between the two metal discs?
Title: Re: How does this clutch work?
Post by: gbritnell on September 25, 2018, 03:19:07 AM
You could do it either way but I would let it float. The diameter is small enough that it won't (shouldn't) flop around.
gbritnell
Title: Re: How does this clutch work?
Post by: Ian S C on September 25, 2018, 03:34:35 AM
I'v seen suggested that slices of wine bottle corks glued to the clutch disc work ok.Don't have to be cut evenly at first, just stick them on, then dress to a flat after the glue has set/cured. Another source of cork is the old fashoned cork place mats for the dinning room table.
Ian S C
Title: Re: How does this clutch work?
Post by: Bluechip on September 25, 2018, 08:20:08 AM
Cork floor tiles are readily available ( in UK anyway   :thinking: ) Good for lining tool-box drawers  :ThumbsUp:

The greeny-grey fiberglass PCB laminate is usually FR4 grade. ( fibre ?? )

Some clutches I encountered on old computer stuff were made from SRBF.

I would go for for leather.

Dave
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 02:31:05 PM
Cuttings from the west coast of Canada has kindly volunteered to send me a piece of friction material from McMaster Carr. So far I have two or three recommendations for leather, one for plywood like I originally suggested, and one for an abrasive disc. The whole idea of a friction clutch like this is that it engages gradually, and not with a sudden grab like a jaw clutch. I think that lets out the abrasive disc suggestion. I do have a cone clutch which I designed a few years ago, on which the cone material is oak wood. It works very well, but then again my engines are only very fractional horsepower engines.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 03:16:35 PM
After cutting the four plates of 01 material to size and milling a notch in the area that will be machined away as a last step, I milled a notch 0.100" deep in all four plates and then with them clamped in a vice I ran a mig weld across all four plates in the bottom of the slot. Then any weld which was "proud" of the plate surface was removed with my 1/2" wide electric belt sander. Now I can grip all four plates together in the vice for farther machining operations.
(https://imageshack.com/a/img922/9356/YArZBL.jpg)
(https://imageshack.com/a/img922/8049/gCYKTA.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 04:38:41 PM
Here are a couple of borderline awful pictures of drilling the appropriate holes in the stack of comma plates, and the final shape marked out on the drilled stack. Now it's cutter, file,  and grinder time.
(https://imageshack.com/a/img924/5413/7LUCK0.jpg)
(https://imageshack.com/a/img924/9471/A0rSSm.jpg)
Title: Re: How does this clutch work?
Post by: Stuart on September 25, 2018, 05:21:06 PM
How about red fiber

It’s like a compressed paper and it’s red of course

Jo will know it as the brake linings for old British motor bikes why befor the used an asbestos lining but after the wooden brake blocks


Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 05:49:25 PM
One more thing before I cut loose with files and grinders. If you remember, I mentioned making "filing buttons" to accurately file the radii onto the ends of these comma shaped pieces. This shows the filing buttons in place in both ends. They are made from 01, and oil hardened to the max. A file will not touch them. Now when I file the rad on the comma shaped pieces, they should end up perfect. Then the filing buttons go into a jar where I keep all the different sizes I have made.
(https://imageshack.com/a/img924/1304/iYtvJu.jpg)
Title: Re: How does this clutch work?
Post by: crueby on September 25, 2018, 06:35:24 PM
Still watching along, great progress...
Title: Re: How does this clutch work?
Post by: Kim on September 25, 2018, 08:45:53 PM
Hmm... Have you changed where you're hosting your pictures Brian?  I've been missing them for the last few posts.  Looks like they are being blocked by my work's firewall.

Guess I'll have to wait till I get home to see all your progress.  But I have no doubt its excellent! :)
Kim
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 10:01:48 PM
The fingers are all finished, filed and fitted. I am happy with the results so far. Now I can harden them. Those 3/16" diameter pins in the assembly are just scrap pieces I had available. The hardened filing buttons and pieces of 3/16" pins are shown along with the comma shaped pieces. Tomorrow I will make proper length pins with snap rings, and make some washers out of the 01 material I have left.
(https://imageshack.com/a/img921/7058/lAHXf5.jpg)
(https://imageshack.com/a/img923/1087/kYsooT.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 25, 2018, 10:03:46 PM
Kim--I am now using Image Shack to host my pictures but that is old news. I changed when Photobucket went nuts and were trying to ransom all of our pictures.---Brian
Title: Re: How does this clutch work?
Post by: Ye-Ole Steam Dude on September 25, 2018, 11:04:39 PM
Looking really good Brian.

Have a great day,
Thomas
Title: Re: How does this clutch work?
Post by: Tennessee Whiskey on September 25, 2018, 11:58:20 PM
I think the “comma thingy” is actually called a “finger”

Whiskey
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 26, 2018, 01:05:05 AM
Well, I've never to my knowledge been given the "comma", but remember a number of times I have been given the "finger"---you're probably right.
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 26, 2018, 10:20:42 PM
This was one of the days when I worked all day and don't have a lot to show for it. I drilled and tapped the end of the shaft for a threaded stud, shortened up a spring to fit, and drilled and tapped the holes to mount the sprocket. The sprocket had to be bored to fit on the hub. Tomorrow I'll make the proper pivot pins.
(https://imageshack.com/a/img922/9271/UzycAX.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 27, 2018, 12:26:14 AM
I think this clutch is going to work. Now that I have the spring in place and the appropriate washers and bushings made, I have assembled it with a clamp ring on the side which will normally hold the friction disc and flywheel. The sliding cone does indeed make the four "fingers" expand when pushed by hand, and the resulting action makes the entire pack expand about 1/16" linearly. That isn't much, but  it's surely enough to clamp the friction disc securely between two faces. I find this quite exciting.
Title: Re: How does this clutch work?
Post by: crueby on September 27, 2018, 12:42:42 AM
Excellent, great when it all comes together!
Title: Re: How does this clutch work?
Post by: Ian S C on September 27, 2018, 03:38:35 AM
With the friction disc floating, leather or other flexable material could be glued on both sides of a steel , or just about any rigid and thin disc.
Ian S C
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 27, 2018, 07:10:56 PM
I just had one of those mornings we don't like to talk about much. After fully assembling all the clutch pieces, I seen that one of the 01 steel washers could be shaved thinner to make things work better. So I did--and then it wouldn't work at all. So--I got to make a brand new washer from 01. Then I noticed that the bushing which the sliding cone slides on could be made 3/16" shorter to make a more compact package, so I did---and then it wouldn't work at all. So---I got to make a brand new 01 steel bushing. I hope I don't see anything else that needs improving!!! I may make the flywheel this afternoon, and I still have to harden all of the 01 steel pieces. I wish I had made that sliding cone out of 01, but I didn't have any 01 that size. I might ask a local shop about case hardening it.
(https://imageshack.com/a/img923/2263/Icthq5.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 27, 2018, 08:43:10 PM
So--If I had my friction material, we're ready to rock and roll. Since there is no way to show inanimate pictures and tell people "it works", I will be rigging a drive and a clutch handle and setting up a live performance I can take a video of.
(https://imageshack.com/a/img922/1223/iTyQfw.jpg)
(https://imageshack.com/a/img921/9938/RDICav.jpg)
Title: Re: How does this clutch work?
Post by: Admiral_dk on September 27, 2018, 09:19:15 PM
Looks very nice so far Brian  :ThumbsUp:   :popcorn:
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 27, 2018, 11:22:30 PM
I've had a revelation this afternoon!! My back was getting sore from standing at the lathe, so I decided to do a bit more studying on clutches, looking at dragsaw videos. When I made the dog clutch on my drag saw, the sliding portion of the dog clutch was moved by two 3/16" diameter pins thru the clutch handle as shown in the first picture. It worked, but I thought that the minimal contact between the round pins and the slot in the sliding cone would probably have been a problem. Today, I replayed all the YouTube dragsaw videos, and SHAZAM!!!--I seen that on the full size machine, there were actually two bronze crescents that fit into the groove on the sliding cone.--See second picture. Damn!!! Learn something new every day!!!
(https://imageshack.com/a/img922/397/1issh7.jpg)
(https://imageshack.com/a/img923/7164/D3DhQ7.jpg)
Title: Re: How does this clutch work?
Post by: crueby on September 28, 2018, 01:44:37 AM
Nice catch!  On the dog clutch for the track drive on the marion shovel, it used a full ring rather than the two crescents, but same idea. Gotta go back and look at the pictures to see how they assembled that...!
Title: Re: How does this clutch work?
Post by: 10KPete on September 28, 2018, 02:03:06 AM
Yep, the collet closer on my 10K is like that...

Pete
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 28, 2018, 02:44:50 PM
I can get very close to what was originally designed by cutting the blue inserts from bronze, soldering on stub shafts, and using a piece of 2 1/2" std. pipe to form the outer housing. Not really sure that I want t go to all that bother, but maybe. A lot depends on how well I can silver solder onto bronze.
(https://imageshack.com/a/img922/2833/kQ1y3F.jpg)
Title: Re: How does this clutch work?
Post by: crueby on September 28, 2018, 02:48:46 PM
Nice catch!  On the dog clutch for the track drive on the marion shovel, it used a full ring rather than the two crescents, but same idea. Gotta go back and look at the pictures to see how they assembled that...!
Found pics of the one on the Marion - they also did it in two halves like you show, they meet at the ends and have a bolted flange to form the full circle inside the groove. Never noticed that, may have when I went to make it (maybe).
Anyway, back to yours!
Chris
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 28, 2018, 07:21:16 PM
Oh yeah baby--I had some brass or bronze, (I don't know which and for what I'm doing it doesn't matter). Now I'm off to see a friend who will send my sliding cone out with some of his stuff to get case hardened.
(https://imageshack.com/a/img922/1111/eE4NkQ.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 30, 2018, 12:45:02 AM
All of my clutches 01 steel parts have been heated to orange/red, quenched in oil, and then baked in good wife's oven for 2 1/2 hours at 350 degrees. The heating and quenching makes them diamond hard, but very brittle. The oven heat soak leaved them hard but takes away the brittleness. The cone part of the clutch, which was made from mild steel has been sent out for case hardening. The bushing which fits between the cone and the shaft is also made from 01 steel, and has been heated, quenched, and tempered. It is not in the picture, because the surface finish was SO UGLY that I am ashamed to show it. On my very last pass on the o.d. I didn't retract the cutting tool before backing it away from the chuck, and it left a spiral gouge full length of the bushing. There wasn't enough material left to do a clean-up pass without going undersize. I dressed it with 200 grit carborundum strip paper, which takes off only about half a thou but cleans up a lot of the minor tooling marks, but the spiral gouge is still there. It won't affect anything, and will in fact act to retain some lubrication between the outer diameter of the bushing and the steel cone which slides on it, but it looks really nasty. Once everything is assembled it won't be visible.
(https://imageshack.com/a/img922/4237/asqMkI.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on September 30, 2018, 11:44:17 PM
Today I'm reduced to "farting around". Can't do much on the clutch assembly until I get the friction material and the part I sent out for case hardening back. I did accomplish one thing--a close examination of that big 8" wobbly v-belt pulley that I've used on numerous set-ups showed that two of the spokes were broken, so I went down to Canadian Tire and bought a new pulley and a couple of cheapo 1/2" dia. pillow block bearings. I modelled them this afternoon for something to do. The actual test set-up for video is going to look like this.
(https://imageshack.com/a/img924/5279/QcqKYt.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 01, 2018, 08:31:27 PM
I have reached the "Can't do anymore" point. I have to wait now for my friction material and my case hardened expander cone. This is the mechanism which operates the clutch. The ends of the flatbar are left untrimmed for now, until I assemble everything.
(https://imageshack.com/a/img922/2298/SgKKXM.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 02, 2018, 12:08:53 AM
A huge THANK YOU going out to "Cuttings" from beautiful British Columbia for two pieces of friction disc material that came in my mail today.---Brian Rupnow
(https://imageshack.com/a/img922/2700/0PzcgQ.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 02, 2018, 11:21:04 PM
This will be (more or less) the set-up for testing the clutch. An electric motor is going to drive the large pulley via a v-belt. The sprocket which is bolted to the driven hub of the clutch will drive a second smaller sprocket when the clutch is engaged, thru a #35 pitch roller chain. In order for a clutch like this to function properly, there has to be some resistance to turning. If there is no resistance to turning, then just the fact that the clutch sprocket is setting on a revolving shaft will make the sprocket turn also. The resistance in this case will be provided by a nylon pellet under a #10-24 set screw thru the side of the small sprocket shaft housing. I will be able to vary the resistance to turning by tightening down the set screw against the shaft which carries the small sprocket.
(https://imageshack.com/a/img922/1026/0t50ab.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 05, 2018, 08:07:20 PM
And now we are in "wait mode". I can't do anymore until my case hardened expander hub comes back from case hardening.--And I can't call the guy and hurry him along, because its being done as a "favour". The set-up as shown lets the shaft revolve freely without turning the sprocket. it also lets the sprockets and chain revolve freely without rotating the shaft. I may have to adjust the width of the wooden stand, but won't know until the expander hub is installed and anchored in the correct place.
(https://imageshack.com/a/img923/9060/VWD5Wv.jpg)
Title: Re: How does this clutch work?
Post by: Roger B on October 05, 2018, 08:21:21 PM
Just catching up with this one. I have seen various versions of this design in old engine books. Looking foreword to seeing how it works  :ThumbsUp:  :ThumbsUp:  :wine1:
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 05, 2018, 08:27:05 PM
Hi Roger--this is a new one for me also, and I find it quite interesting.---Brian
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 08, 2018, 10:46:42 PM
Spent today eating turkey and pumpkin pie--House was full of adult children and grandchildren. Good wife cooked her usual fantastic thanksgiving dinner.--and when I wasn't actively engaged in being grandpa I was thinking about clutches. Earlier in the week I had looked up and studied on a wrap-spring clutch, which I have never heard of before but now I know how they work. Also looked at a number of "over center" manual clutches and electromagnetic over-center clutches. I have built cone style clutches and expanding shoe clutches and dog clutches. They all seem to work, but they all (except for the dog clutch) seem to have too many parts to "miniaturize" down to a point where they work repeatably and consistently on an engine with a 3/8" crankshaft. I also looked at a proprietary friction clutch which is sold for go-carts and mini-bikes, but couldn't really tell how it operated. I hope to get the final part for my current clutch build back from case hardening this week to finish it up.---Brian
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 09, 2018, 10:35:45 PM
Today I'm just dickin' around. No real work and my clutch part isn't back from case hardening yet. Of all the different clutches I've designed, the expanding shoe clutch seems to lend itself best to installing on a small engine. It is relatively small at 1 3/4" diameter, and it doesn't put any axial load into the crankshaft. I checked out all of my engines, and the one most suited to adding a clutch to was the flathead engine I had featured in the Home Shop Machinist magazine a few years ago.
(https://imageshack.com/a/img924/5131/Q82GeE.jpg)
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 15, 2018, 11:43:40 PM
It seems that my case hardening friend has let me down. I will give him one more week and then I will get the part back and use it unhardened, or else build another from 01 and harden it myself.---Sorry about the delay.---Brian
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 19, 2018, 04:43:42 PM
Okay--We're back in the saddle again on this project. I just went down to the machine shop that was going to have my tapered hub case hardened, and then didn't.--Moving on--I'm going out to my main garage right now and set this up with a motor to drive it, and see if and how well it works. A video and picture will be posted here shortly.---Brian
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 19, 2018, 06:29:40 PM
And as I promised, here we have a still shot of the assembled clutch, and a nice video of it in operation---Brian
(https://imageshack.com/a/img922/7654/cc2Ibx.jpg)
JS0IhUyVdO0t=4s
Title: Re: How does this clutch work?
Post by: Brian Rupnow on October 19, 2018, 10:19:03 PM
As promised, here are all the engineering drawings to fabricate this clutch.---Brian
http://www.mediafire.com/file/x7shbmds6box782/FRICTION_CLUTCH_BASED_ON_DRAGSAW.zip/file