# Mechanical Clutch



## Brian Rupnow (Dec 19, 2012)

My brain never stops!!! Not all of my ideas are good ones, but I never run out of mechanical things to think about. Playing about with my model sawmill has got me thinking about simple mechanical clutches. Not something that tightens or loosens a drive belt, and not something that creates "drag" when disengaged. Rather some device that totally and completely disengages the driveshaft from whatever it is driving, and can be engaged softly like the clutch on an automobile, not with a sudden "grab and lurch". It would have to be simple, cheap, small, and a minimum of moving parts. I have many small, single race ball bearings from disassembling various "things" over the years, and they will take a lot of axial as well as radial pressure without failing. I was doodling on a piece of paper, and where the levers are in the sketch, think about a Destaco style clamp. Not the ones with the swinging lever, but the push/pull type. I see the friction material as being oak or maple, glued into a brass or aluminum housing. Not sure if I will build something like this or not, but it is intriguing!!!


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## Jasonb (Dec 20, 2012)

Very much like the cone clutches found on some hit & miss engines except a handwheel was turned to engage and isengage them rather than use a lever.

The make part of the cone had friction material on it


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## aonemarine (Dec 20, 2012)

Some outdrives on boats use the same set up and some posi traction rears.....steel on steel!


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## crankshafter (Dec 20, 2012)

Brian Rupnow said:


> My brain never stops!!! Not all of my ideas are good ones, but I never run out of mechanical things to think about. Playing about with my model sawmill has got me thinking about simple mechanical clutches. Not something that tightens or loosens a drive belt, and not something that creates "drag" when disengaged. Rather some device that totally and completely disengages the driveshaft from whatever it is driving, and can be engaged softly like the clutch on an automobile, not with a sudden "grab and lurch". It would have to be simple, cheap, small, and a minimum of moving parts. I have many small, single race ball bearings from disassembling various "things" over the years, and they will take a lot of axial as well as radial pressure without failing. I was doodling on a piece of paper, and where the levers are in the sketch, think about a Destaco style clamp. Not the ones with the swinging lever, but the push/pull type. I see the friction material as being oak or maple, glued into a brass or aluminum housing. Not sure if I will build something like this or not, but it is intriguing!!!


Hi Brian.
I have been following this build( and all your other ones)But when you say: "Not sure if I will build something like this or not, but it is intriguing!!!"
I know you will.;D

Best Regards
CS


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## rodw (Dec 20, 2012)

Brian, I think back in the day they preferred to use laminated leather for cones in friction clutches. Back to my shearing shed experience, an overhead shaft carried a large friction wheel for each shearing stand. A leather cone was used to engage with this wheel to drive a smaller shaft at right angles. I can't find a photo but photo 3 on this PDF shows one on a single stand electric version. They do mention wood cones in this document but I never saw one. Leather eventually gave way to synthetic cones. 

http://www.kondiningroup.com.au/web_multimedia/startDownload.asp?strMultimediaFileName=FA128-28.pdf

You might be able to get away with machining your clutch cone out of a plastic. I reckon that you could machine laminated discs of leather into a cone shape as it is very stiff.

I also remember a ride on mower we had as a kid that had a siimilar leather cone mounted directly to a 8 hp engine drive shaft that sat between two friction plates mounted to the rear axle, one on each side of the cone. Moving a lever moved the engine sideways. One side drove forwards, moving the cone to the other plate drive in reverse and of course, in the middle was neutral.


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## myrickman (Dec 20, 2012)

The angle of the taper determines whether the clutch will lock or not. It depends on the coefficient of friction of the 2 materials. If you do a google search, there is a wealth of info out there. I'll have to check the angle on a cast iron clutch on a stationary engine  which is currently removed.


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## Brian Rupnow (Dec 22, 2012)

And moving from hand doodles to CAD doodles, we have this. What I have attempted to do here is to ensure that all axial loads are transferred thru the ball bearings instead of any sliding surfaces betwen rotating mechanical parts.


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## Brian Rupnow (Dec 22, 2012)

Bad on me!!! I forgot to show the drive pin and slot in the shaft in the first drawing I posted.


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## Brian Rupnow (Dec 22, 2012)

This is the first part I will make. As you can see, I have added a second groove to it, simply because I have the room. This entire clutch is not going to be a study in superior engineering. Its something to do to keep me from going nuts during the ensuing festive season. I THINK it will work fine and I will post drawings as I go along, because I have to make them anyways for myself. If it works really really great, then you can copy the drawings and save them. If it doesn't work, then at least it will have amused you.


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## Brian Rupnow (Dec 22, 2012)

Here is a little trick that works for me. When I want to go to a non critical flat bottomed hole in a part, which has a smaller thru bore already in it, I stick this 1" dia. 4 flute end mill in the tailstock chuck with my lathe on its lowest speed (about 150 rpm) and crank it in. This seems to put a smaller chip load on the lathe than cranking in a 1" drill bit, and I can go full depth in one shot without having to worry about a tapered bottom like you get from a drill. This side will now be opened out with a boring tool to 1 5/16" diameter, and then I will set my topslide over 25 degrees to make the final taper.


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## Brian Rupnow (Dec 22, 2012)

There!!! Enough silliness for one evening. Time to go spend some wife time.


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## hammer2100 (Dec 22, 2012)

Brian,
      First I like your idea, I like  the idea of the Oak. My Grandfather's family used Hickory bands in Model T Fords, I have one of the bands. But I have a idea for you that might help.
I have seen something like your design smoewhere but they used the cone part of the clutch to sycronize the shafts than a splined collar slipped over the input shaft. This would then
take away the thrust load on the bearings. Just a thought.
      Hammer


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## sssfox (Dec 22, 2012)

hammer2100 said:


> Brian,
> 
> I have seen something like your design smoewhere but they used the cone part of the clutch to sycronize the shafts than a splined collar slipped over the input shaft. This would then
> take away the thrust load on the bearings. Just a thought.
> Hammer



It's called a synchromesh transmission.  The gears are always meshed and the little cone/clutch thingies connect them to the output shaft.

Here is an explanation here:
http://en.wikipedia.org/wiki/Manual_transmission#Synchromesh

That would probably work well in this application.  It wouldn't be necessary to maintain pressure on the lever.


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## Brian Rupnow (Dec 23, 2012)

Thanks for looking and commenting guys. The plan keeps evolving!!!  My whole premise behind this clutch is that the bearings do take up all the axial load. Ball bearings like the ones I am using (because I already have them) will take amazing radial loads, but they will take considerable axial loads as well, though not as great. As for holding the lever in to keep the clutch engaged, this latest drawing will show what I have in mind.  On the extreme right hand piece the outer diameter of the body will have a 1 1/4" thread on an extended boss and will be threaded thru a plate with a 1 1/4" thread, which is attached to the baseplate. A handle on it will engage or disengage the clutch by swinging in an arc to advance the entire end (holding the bearing) on the threads. Since the threads on a 1 1/4" nut are quite coarse, a 45 degree swing of the handle should advance all the pieces sufficiently to engage the clutch, and it should hold its position there untill the handle is revolved 1/4 turn in the opposite direction. This is very hard to get your head around, but the drawing I have posted should make it clearer.---Brian


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## Dave Sohlstrom (Dec 23, 2012)

From the Willamette Iron & Steel Works 1925 catalog they were using the same principal on there donkey winches used here in the PNW. Here is a scan of there friction device.

Dave


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## Brian Rupnow (Dec 23, 2012)

Thanks Dave. And here's how the other side turned out. I am always amazed by the infinitesmaly (is that a word?) small difference between a press fit and a Loctite fit!!! This was supposed to be a "light press fit" . It turned out by about one zillionth to be a Loctite fit. No fear though. I had reamed the bore on the fabricated part and it was right on. So---I slipped a piece of 3/8" cold rolled shaft thru the fab'd part, slipped the bearing over that, slathered on a bit of 638 Loctite, and together it went. Concentricity gaurenteed.


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## Brian Rupnow (Dec 23, 2012)

Some observant soul on "the other" forum just pointed out that the slot in the shaft should be centered on the pin to allow the oak disc and its holder freedom to move in either direction.---And he's absolutely right!!!


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## Brian Rupnow (Dec 23, 2012)




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## Brian Rupnow (Dec 23, 2012)




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## Charles Lamont (Dec 23, 2012)

I don't think oak is ideal for this job. I would say it is too coarse and too open grained. Of course, if it is all you have, then it is worth a try. If you later decide to refine it, I would suggest something hard with a fine, even grain and preferably an oily nature. Lignum Vitae would have been ideal but is now unobtanium and if I remember rightly Goncalo Alves is a reasonable substitute. African Blackwood might be good too. Less exotic alternatives, without the desirable oiliness might include Rock Maple or Apple. Or Tufnol.

I think I would have used a smaller cone angle, but have done no calculations.


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## Brian Rupnow (Dec 23, 2012)

But the oak was FREE!!!---And I'm just guessing at the cone angle.


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## Brian Rupnow (Dec 24, 2012)

There----Thats the outer clutch housing finished. I did manage to get a much better fit on the bearing this time. I lined both pieces up on an old 3/8" bolt to take this picture, as I couldn't find a piece of 3/8" cold rolled. Maybe I will have time to make the oak friction cone and epoxy it in place later today. Gotta go now and do Christmas things.


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## Brian Rupnow (Dec 24, 2012)

The oak, turned to correct o.d. and epoxied into the outer metal housing.


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## Brian Rupnow (Dec 24, 2012)

The oak machines very cleanly at 1620 rpm, with HSS turning tools and/or carbide boring tools.


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## kutzdibutz (Dec 24, 2012)

Brian,
very good to know! I would have expected a dedicated cutting angle to be required to cut wood properly. Very good to know it works with the 'standard' tools. 

Cheers, Karsten


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## Brian Rupnow (Dec 24, 2012)

I have machined oak before, for some of the wacky things I build, and I too was surprised by how cleanly it machines with my standard tooling. I think the fact that it is a hardwood and the high rpm are the ticket. I have tried machining softer woods like pine, but the tools must be razor sharp to get good results.


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## Brian Rupnow (Dec 24, 2012)

I "blued" the inside of the metal cone with some Dykem layout dye, and after it had completely dried I set up both parts on a 3/8" alignment shaft and spun them in opposite directions by hand. The initial results appear very good. I had to swing my topslide over to the opposite side to turn the oak, and I set it to 25 degrees by the protractor built into the topslide. The protractor is marked in 1 degree increments and is only slightly better than a guess. I know that if things weren't perfectly concentric, they would be after the first 5 minutes of actual use. From the pattern I see where the Dykem wore off the aluminum and onto the oak, I think I got it pretty close.


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## Brian Rupnow (Dec 26, 2012)

This morning I made up a drawing of the main support bearing. More to determine whether I have a piece of material big enough or not.


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## Brian Rupnow (Dec 26, 2012)

Well. no 3/4" plate, but I  did find a chunk of 1" aluminum plate big enough to carve this from.


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## Brian Rupnow (Dec 27, 2012)

Thru good luck, 4$, and some creative begging I was able to scoop a 1 1/4"-7 hex nut and about 3" of threaded rod this morning. I keep changing the right hand end of the clutch, and refining it so that none of the rotational moments feed back thru to the thread which forces the clutch faces together. The wood in the background is boards sawn from my model sawmill.


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## Brian Rupnow (Dec 27, 2012)

Sometimes I think that the quality of my life would improve if I could cut single point threads on my lathe!!! However I can't. First it was learners inability, Then somehting went crunch in the leadscrew drive. So----I live with work arounds.


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## Brian Rupnow (Dec 27, 2012)

I just finished the part which "activates" the clutch cones, to move them together or apart. I was going to weld the threaded portion to the turned portion of shaft, but found out that the piece of what I thought was 1 1/2 diameter steel was actually cast iron. Thats okay though. Since the threaded portion sets up against a shoulder when the clutch is being engaged, Loctite 638 will suffice to keep the two pieces together. The cross hole for an anti rotation pin has not been drilled yet.


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## Brian Rupnow (Dec 27, 2012)

The design of the right hand end of this clutch mechanism keeps evolving, as I think of potential problem areas and ways to overcome them. This is the latest vesion, in which the part with the external thread on it has an anti rotation pin riding in a slot, so that none of the rotational moments up at the "cone" end can be transferred to the part with the external thread, causing it to tighten or loosen by itself.


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## mygrizzly1022 (Dec 28, 2012)

Hi Brian
I am having a hard time believing that single point threading and a Crunch could possible intimidate you. The tenacity with which you pursue your various projects is such that the threading issue complete with Crunch should provide a miniscule challenge.
I look forward to your thread on Beating the crunch. The lathe you have seems to have a reasonably good reputation as does the Bee so my guess is once you attack it, you will win, and work a rounds will not be necessary.
Regards Bert


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## Brian Rupnow (Dec 28, 2012)

This is where I'm going next---


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## Brian Rupnow (Dec 28, 2012)

mygrizzly1022 said:


> Hi Brian
> I am having a hard time believing that single point threading and a Crunch could possible intimidate you. The tenacity with which you pursue your various projects is such that the threading issue complete with Crunch should provide a miniscule challenge.
> I look forward to your thread on Beating the crunch. The lathe you have seems to have a reasonably good reputation as does the Bee so my guess is once you attack it, you will win, and work a rounds will not be necessary.
> Regards Bert


Bert---The reason that I haven't persued this issue is that the lathes lowest speed is 115 rpm, and thats simply too fast to thread with. And I believe that on this lathe, to reverse it, you have to shut off the motor, reverse it, and then restart the motor.


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## Brian Rupnow (Dec 28, 2012)

Well, is it starting to look interesting yet? Thats all the internal parts finished. The #10-24 threaded rod screwed into one of the tapped holes in the ring was just there to give me a temporary handle to see how smoothly things turned. While I had the rotary table set up, I also added the 3/16" hole for the anti rotation cross pin in the part which I made earlier today.


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## starnovice (Dec 28, 2012)

Very interesting Brian.  When it is done maybe you can connect it to the sawmill to demonstrate it.

Pat


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## Brian Rupnow (Dec 28, 2012)

starnovice said:


> Very interesting Brian.  When it is done maybe you can connect it to the sawmill to demonstrate it.
> 
> Pat


Starnovice--Thats been my intent all along. I want to use the Atkinson as my power source, but I don't want to have to stop and start the engine. If this clutch is succesfull, I can leave the engine running while I do any tweaking I want to with the sawmill, then engage the clutch and have the engine saw under power.


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## Brian Rupnow (Dec 29, 2012)

In my great surge of creativity and rush to complete the mechanical clutch, I did the unthinkable!!! I designed a part which, although it looks just great, simply can't be built with the tooling I have. That cut out in the center with a 0.906" radius is impossible for me to machine. The design engineer thought it made perfect sense. The machinist looked at it and after studying the drawing for a few minutes said "How in H%$# am I supposed to machine that???" So---The design engineer sat down, screatched his head for a while, and said "I Know!!! We'll make it in two pieces with the split line right on the center of that .375 width and bolt the two peices together with a couple of alignment dowels to keep everything concentric. And thats what he did!!! (The alignment dowels are not shown in the solid model.)


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## Brian Rupnow (Dec 30, 2012)

Making the endblock in two pieces is the only way I can make this part.


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## Brian Rupnow (Dec 30, 2012)

Wanting to do this in as few set-ups as possible, I clamped a 2" x 1" x 12" piece of aluminum bar to the mill table with a 1/4" spacer bar under each end. This was to raise the piece being machined up of the mill table so I could drill thru it without damaging the mill table. I aligned it very carefully with the right to left axis of the mill and then cut away two areas to the finished thicknesses of .938" and .813", both about 3/8" longer than the part it would make. Then all bores except one and all bolt holes and tapped holes were done without having to move the part. I also milled away the 1" x 3/16" x 2" relief on the mating faces while in this set-up. The faces which were machined will face each other when the two parts are seperated and bolted together. Of course that means that there is one bore which will be on the far side as well as 4 bolt counterbores. I will flip the part over, pick up position off of the .75" reamed hole, and then put in the final 1.5" dia. counterbore and the c'bores for the bolt heads. I hope I have this sequence figured out correctly, and it seems to be going okay so far. I will use the round piece that registers in the .75 bore and the 1.5" bore as an alignment tool when bolting and doweling the two pieces together.


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## Brian Rupnow (Jan 1, 2013)

Happy New Year everybody!!! Things keep moving along, and as the work progresses the design keeps evolving. These drawings are current and will not change, because the parts are made and assembled. I will be posting a video a bit later today of this actuating mechanism working.


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## Brian Rupnow (Jan 1, 2013)

Here is a rather shabby quality video of the clutch actuator working. I am fighting with my camera today, and this is the best of 3 videos I made of the same thing. Its not great, but it does show the action very well.----Brian


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## Brian Rupnow (Jan 2, 2013)

This is the last part I have to make, other than the shaft and the final pulley (which I will change to a double groove). I finished the part this morning that looks like a large pillow block bearing, all except for rounding the top, which I do on my big stationary belt sander out in the main garage. However, wife and I are both sick with the cold. I'm recovering, she's in bed----And her bedroom is right above the main garage. I won't be firing up the big belt sander until wife is up and about.


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## Brian Rupnow (Jan 2, 2013)

Almost finished!!! I have to make a pulley for the outboard end and put a slot in the shaft, thats all. What about the gap?--Oh, that gap. Well---I left the oak about .080" longer than what the drawing called for, to give me some "extra" friction surface to wear away, then went and built that bottom plate to the blueprint. Thats okay. I sort of figures there would be some fine tuning when I got to this stage of things.


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## starnovice (Jan 2, 2013)

Looking forward to seeing it used on the sawmill!

Pat


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## trumpy81 (Jan 2, 2013)

Brian, that's an interesting piece you have there. I'd be interested in seeing just how it performs.

It could be useful for many things and if scaled up a little, I can see a use for it on my Chinese lathe 

Loved the video too, more please!


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## Gedeon Spilett (Jan 3, 2013)

looking at the pattern of dye marks in the femeale cone, of the same "thead" than the top slide screw I bet, a setting of the top slide will reduce this wobbling, if the slides are worn regularly along their ways... turning a morse cone in my lathe is now impossible without a major overhaul of the topslide, someday, but morse cone are not that expensive...  
Cheers
I'm fond of yours thread, all of them, awsome engines.


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## Brian Rupnow (Jan 3, 2013)

Thanks for looking and commenting, fellows. I will be finished with the clutch this week, and will definitly post a video of it in operation.


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## Brian Rupnow (Jan 3, 2013)

How do you put a 3/32" slot thru a 3/8" diameter steel shaft?---Answer: The same way porcupines make love.---VERY carefully!!! I drilled thru the shaft at what would become the ends of the slot, then walked a 3/32 carbide endmill back and forth taking about .010 doc each pass. Held my breath the whole time, but it turned out okay. I thought I was ready for final assembly, then realized that I still hadn't made the 3/8" diameter shaft collar that prevents the pulley part of the clutch from following the friction disc along the shaft when the clutch is disengaged. Then after taking another look at the assembly drawing, I realized that if I put a set screw thru the outer diameter of the collar the normal way, I wouldn't be able to get at it to tighten it up unless I drilled an access hole thru the face of the pulley. I will look at it more closely tomorrow. I may have to put the set screw thru from the side at an angle. At any rate, here is a picture of all the parts except the shaft collar and the outer pulley.


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## Brian Rupnow (Jan 4, 2013)

Just enough room--barely, barely---with a cut down allen wrench, to reach in and tighten the screws in the shaft collar.


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## sssfox (Jan 4, 2013)

Brian Rupnow said:


> Just enough room--barely, barely---with a cut down allen wrench, to reach in and tighten the screws in the shaft collar.



How did you drill those holes in there?


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## Brian Rupnow (Jan 4, 2013)

Its hard to see in the picture, but this drawing will clear it up some. That piece with the set screws in it is a seperate piece altogether. It was fully machined, then slid over the shaft into position. It shows up as the red part in the drawing.---Brian


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## sssfox (Jan 4, 2013)

Got it.  Thanks.


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## Brian Rupnow (Jan 4, 2013)

The clutch works!!! At least it works as near as I can tell by turning the shaft with a pair of vice grips while engaging and disengaging the handle and holding the cone-pulley with my OTHER hand. Yeah, I know. Thats 3 hands!!! Can't really tell a lot until I get this pulley made and get things hooked up with my o-ring drive belts.


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## Brian Rupnow (Jan 4, 2013)

Teaser shot!!! I haven't tapped the set screw threads in the pulley yet, but I just had to see what it looked like. The outer pulley is driven, the inner pulley is the clutched pulley. Although, I suppose it could just as well be the other way round.


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## Brian Rupnow (Jan 5, 2013)

Here we have the promised video of the clutch in operation. Bear in mind that the clutch is brand new, and consequently a bit stiff untill it gets ran for a while and loosens up. The sawmill takes very little power to drive it, but the stiffness in the clutch is the reason that the electric drill was working as hard as it appears in the video. Once this clutch mechanism is fully "run in", it will take very little power away from the engine it is used with. My trusty Canon digital camera has crapped out on me, so I just went and bought a Sony DSC-H90 to make this video.---Brian


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## starnovice (Jan 7, 2013)

Very nice Brian.  Your saw mill must really be built well to be able to take a cut that only produces sawdust the width of the blade and not wander out of the kerf.  Good job!

Pat


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## Brian Rupnow (Jan 7, 2013)

starnovice said:


> Very nice Brian.  Your saw mill must really be built well to be able to take a cut that only produces sawdust the width of the blade and not wander out of the kerf.  Good job!
> 
> Pat


Pat---I hadn't even noticed that. I had to play the video over again to see what you were talking about, and you're right, it was shaving off a cut the width of the blade. I have the clutch working much more freely now. I put a v-belt bulley on it and set it up with a belt drive from ny lathe and drove it at 550 rpm for about 20 minutes to take the stiffness out of it. Its too cold out in my big garage to mess with the atkinson engine now, but when the weather warms up (which may be the end of March) I hope to make a video of the sawmill cutting a log driven by the Atkinson thru the clutch.---Brian


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## BillH (Jan 13, 2013)

I am late to the party but wanted to make a suggestion about single point threading.  For my lathe, I made a hand crank with an expanding collet that fits in back end of the spindle. Works like a charm and easy to do.  Just don't forget it's there when you turn on the lathe!


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## Charles Lamont (Jan 13, 2013)

BillH said:


> I am late to the party but wanted to make a suggestion about single point threading.  For my lathe, I made a hand crank with an expanding collet that fits in back end of the spindle. Works like a charm and easy to do.  Just don't forget it's there when you turn on the lathe!



Oh, you've done that too! As an extra precaution I now disengage the clutch and push the off button before I insert the spindle handle. One of the first lathe accessories I made and indispensable since.


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