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.
Friction clutch for small engines
- Thread starter Brian Rupnow
- Start date
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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!!!
nel2lar
Well-Known Member
centrifugal clutch requires a sharp increase of speed, Brian's engine runs very close to the same speed even under a load
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.
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.
Brian,
I have had some luck with 1/8" Masonite, not the hardened kind as it is too slick. The regular grade gives a good bite on both sides.
I have had some luck with 1/8" Masonite, not the hardened kind as it is too slick. The regular grade gives a good bite on both sides.
Thanks Loren.--A gentleman in British Columbia had some extra friction material from McMaster Carr that was left over from a project, and he has mailed some to me. I just sent out the expander hub today for case hardening, so the project won't get finished for a week or more.---Brian
Never heard of an anti snake anything.--Sounds interesting.
Link to “towsure” friction pads for their own and “bulldog” anti-snake or stabiliser bar..
https://www.towsure.com/bulldog-lc3-3-friction-discs-200q-400q-stabilisers
https://www.towsure.com/bulldog-lc3-3-friction-discs-200q-400q-stabilisers
Brian: I have been following this thread with interest. When I was on the farm, we had a Wisconsin single lung engine with an enclosed clutch assembly and an exterior lever to engage or disengage the clutch. the lever acted as a snap over center motion and the clutch itself was a cone clutch with a l ining. I know you have done a lot of work on your current assembly but it could be the cone clutch complex is a better alternative. John
Anatol
Well-Known Member
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.
Brian, reading this thread is interesting because you understand, just by looking at a machine, how the parts function to handle the forces they experience. They developed that way because other solutions had broken, wore out etc. Its interesting to think about the 'evolution' of such things (at least for me
You discovered a subtlety in an original design (the brass half rings). I assume they function as a kind of split bushing, to 'cradle' the 'drum' and spread the load of pulling it along the shaft. Actually its kind of gimbal. I *guess* you could also imagine it as an uncut ring, like timbale, it you had some way of holding it on the drum - but that would take a collar, or similar.
I'm just kicking around different daring solutions here. Because its fun to think about
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.
Nodaker--I have built a cone clutch, and it works very well, but it is a bit too large to act in this application. It is not an "over center" mechanism, but has a spring loaded latch to hold the clutch engaged. I will try and hunt up the thread I posted while building it and put the link here.---Brian
https://www.homemodelenginemachinist.com/threads/clutch-again.20528/
https://www.homemodelenginemachinist.com/threads/clutch-again.20528/
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I have a full size drag saw that utilizes a cone clutch. It works quite well.
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.
Loren Otto--I didn't say that a cone clutch wouldn't work on a dragsaw. I have also seen videos of them using a dog clutch. I have a great interest in clutches. I have built ( in model size) a cone clutch, a line shaft expanding shoe clutch, a dog clutch, and now this current clutch I'm working on is something new that I haven't built before. The excitement of modelling and building something new (to me) is what drives me in situations like this.---Brian
nel2lar
Well-Known Member
Brian
I have been watching with quite a bit of fascination of the mechanics and the way you solve some of the problems. I was looking through some of my old files and ran upon my old Bolen mower and the clutch system on it, a lite bulb lit up. I was thinking in the idea of the center being a floating belt or chain sprocket with pads around the flats about .500 to .750 from edge. The newest method you have for engage and disengage on the outside the shaft just like you have yours. This has become one of the best projects I've seen in a long time.
Looking good Brian
Nelson
I have been watching with quite a bit of fascination of the mechanics and the way you solve some of the problems. I was looking through some of my old files and ran upon my old Bolen mower and the clutch system on it, a lite bulb lit up. I was thinking in the idea of the center being a floating belt or chain sprocket with pads around the flats about .500 to .750 from edge. The newest method you have for engage and disengage on the outside the shaft just like you have yours. This has become one of the best projects I've seen in a long time.
Looking good Brian
Nelson
Brian,
It appears that McMaster-Carr has started to service Canada. Over the years I would occasionally give it a try ... and was always rejected. A few months ago, I tried again and bingo ... no problems. They charge GST, land the shipment in Canada (ie. no customs clearance fees), with two day courier shipping to my home in Salt Spring Island, BC for about US$20 shipping fee (I suppose depending on size & weight - I ordered about US$60 of various lengths of O ring cord, adhesive, a cutoff blade .... so it wasn't very heavy).
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.
