Help Me Find A Pulley

[Chanceywd]

Or is that pulley part of a centrifugal clutch which then it would be a regular bearing.

 

[etpm]

I am trying to convert an old makita that I don't use anymore into a debarking tool. The kit I bought comes with pulleys for Stihl and Husky. I was hoping one of them would work with the Makita, Doesn't seem like they will. So I need to find a pulley that will work. I figure if I use my digital caliper to find the diameter of the post on the makita I can find something that will work. I am here to ask if anyone know a source for such a thing. If does not have to be very elaborate. The included pulleys are quite simple. Once has a bearing in it the other does not. Suggetions? Tips? Warnings? HELP!View attachment 2410331

Speaking as a machinist those pulleys are not simple, though they look so. They are a pulley and clutch drum combo, and you need both. To use them they must fit the chainsaw shaft properly, both in diameter and length. Since one pulley has no bearing you may be in luck but you will need a machinist to look at and measure things. If the Makita shaft is a standard size for needle bearings then you may be able to have the plain pulley modified so that a needle bearing can be used in it. Hopefully it can just be bored to a larger size to fit the needle bearing. Maybe it is already the proper size and you can just press the needle bearing into the pulley. If the bore is too large then it could be bushed down to fit the needle bearing. But there is also the issue of length. The clutch threads onto the end of that shaft and traps the pulley/clutch drum combo. If the bearing is too long the clutch will bind against the bearing. If the pulley/clutch drum combo is too short then the pulley will move back and forth along the shaft excessively, which may be a problem. My feeling is that the Makita shaft is made to a standard size to fit a standard size needle bearing because that is the cheapest and best way to engineer something like this. In fact, it may be that the pulley/drum combo may already be bored to accept the proper bearing. Look here for standard needle bearing sizes: McMaster-Carr
Look here for needle bearings that use a larger bore: McMaster-Carr
Most needle bearings are the drawn cup style and that is the type of bearing shown in the picture you posted. But there are needle bearings with a thicker outer race which could be used if the bore in the plain bore pulley is too large for a standard drawn cup bearing. This is probably than using a bushing to make the hole smaller to accept the drawn cup bearing, but there may not be enough material in the pulley for the bigger bore. Though it does look like there is plenty of material. If the pulley needs to be bored to accept the larger type bearing you will need a competent machinist to do the work. Don't think you can just drill out the pulley. It may work for a little while but will ultimately fail, and fail soon.
Eric

 

[dstig1]

IIRC Makita chainsaws were made by Dolmar, and I think they have merged now. Can you look for parts from Dolmar?

 

[HawkinsHollow]

Speaking as a machinist those pulleys are not simple, though they look so. They are a pulley and clutch drum combo, and you need both. To use them they must fit the chainsaw shaft properly, both in diameter and length. Since one pulley has no bearing you may be in luck but you will need a machinist to look at and measure things. If the Makita shaft is a standard size for needle bearings then you may be able to have the plain pulley modified so that a needle bearing can be used in it. Hopefully it can just be bored to a larger size to fit the needle bearing. Maybe it is already the proper size and you can just press the needle bearing into the pulley. If the bore is too large then it could be bushed down to fit the needle bearing. But there is also the issue of length. The clutch threads onto the end of that shaft and traps the pulley/clutch drum combo. If the bearing is too long the clutch will bind against the bearing. If the pulley/clutch drum combo is too short then the pulley will move back and forth along the shaft excessively, which may be a problem. My feeling is that the Makita shaft is made to a standard size to fit a standard size needle bearing because that is the cheapest and best way to engineer something like this. In fact, it may be that the pulley/drum combo may already be bored to accept the proper bearing. Look here for standard needle bearing sizes: McMaster-Carr
Look here for needle bearings that use a larger bore: McMaster-Carr
Most needle bearings are the drawn cup style and that is the type of bearing shown in the picture you posted. But there are needle bearings with a thicker outer race which could be used if the bore in the plain bore pulley is too large for a standard drawn cup bearing. This is probably than using a bushing to make the hole smaller to accept the drawn cup bearing, but there may not be enough material in the pulley for the bigger bore. Though it does look like there is plenty of material. If the pulley needs to be bored to accept the larger type bearing you will need a competent machinist to do the work. Don't think you can just drill out the pulley. It may work for a little while but will ultimately fail, and fail soon.
Eric

So you're saying it's possible? Maybe easy, maybe hard? That is a lot to digest, I need to reread that.

 

[HawkinsHollow]

Speaking as a machinist those pulleys are not simple, though they look so. They are a pulley and clutch drum combo.

No there is no clutch involved on the pulleys for the debarker, they just attach to the shaft. Those drums are empty. The entire clutch assembly of the chainsaw is removed.

 

[etpm]

No there is no clutch involved on the pulleys for the debarker, they just attach to the shaft. Those drums are empty. The entire clutch assembly of the chainsaw is removed.

That pulley must be driven somehow and retained somehow. Usually the drum is retained around the clutch with a retaining ring. However, I have seen setups where the drum is retained by the clutch, which is threaded onto the shaft. But I think those were on weedeaters. And why, if the drum isn't used with the clutch, is it even there? I'm confused. If the drum isn't driven by the clutch then I suppose the pulley with the needle bearing could actually contain a sprag clutch and not a regular needle bearing. But then how is the pulley without a bearing driven? Are you sure the pulley isn't driven by the clutch? I looked online for a unit that resembled yours and found a YouTube video that shows installation. In the video the clutch is plainly left in place to drive the drum.
Eric

 

[ning]

That pulley must be driven somehow and retained somehow. Usually the clutch retains the drum, at least that is the only way I have ever seen them work. And why, if the drum isn't used with the clutch, is it even there? I'm confused. If the drum isn't driven by the clutch then I suppose the pulley with the needle bearing could actually contain a sprag clutch and not a regular needle bearing. But then how is the pulley without a bearing driven? Are you sure the pulley isn't driven by the clutch?
Eric

I think what he's saying is that when you make a debarker, you attach the pulley directly to the shaft - you don't use the clutch or drum from the source saw.

 

[etpm]

I think what he's saying is that when you make a debarker, you attach the pulley directly to the shaft - you don't use the clutch or drum from the source saw.

Yes, but the pulley has a drum attached. Why include the drum if it isn't to be driven by a clutch?
Eric

 

[HawkinsHollow]

I think what he's saying is that when you make a debarker, you attach the pulley directly to the shaft - you don't use the clutch or drum from the source saw.

Yes, I'm pretty sure the pulley is attached directly to the shaft, no clutch involved. No idea why it has the drum. Took some measurements with the calipers today. Going to see if I can find something at mcmaster carr. Amazon has quite a few pulleys as well.

 

[etpm]

Yes, I'm pretty sure the pulley is attached directly to the shaft, no clutch involved. No idea why it has the drum. Took some measurements with the calipers today. Going to see if I can find something at mcmaster carr. Amazon has quite a few pulleys as well.

All of the debarkers I found online use the clutch. I'm mystified. Can you provide a link to the exact brand and model so that maybe I can find the manual online to satisfy my curiosity?
Thanks,
Eric