Question regarding leather strop wheel?

[Tannikca]

I'm interested in sharpening my carving tools with a leather strop wheel and I was wondering if there is a certain number of rpms the wheel should be turning.

[AlArchie]

I'm not sure there is a "standard" for rpm on a leather strop, but Tormek turns theirs at 90 RPM, and a couple of the clones turn between that and 60.

RPM, however isn't the definitive factor. Feet or inches per minute is a bit more accurate, and that will vary directly with the diameter of the wheel..

A 6" wheel turning at 90 RPM, for example, will have a surface speed of roughly 141 FPM. A 10" wheel turning at the same RPM will have a surface speed of 235 FPM.

To find the FPM of your proposed wheel, multiply the wheel diameter by 3.1415 (PI) for the circumference, then by the RPM of the wheel. That will give you the linear speed of the surface in inches per minute. Divide that by 12 (12 inches to the foot) to get FPM.

PI x D x RPM/ 12= FPM surface speed.

I'd try to get the FPM somewhwere in the range of theTormek and the clones. Tormek T-7 has a 10" diameter wheel so their FPM would run roughly 235 FPM at the 90 RPM shaft speed.

Hope that helps.

Al

[CarverFromNoWhere]

Looks like you have got it coverd Al Thumbs Up.
Carl

[Tannikca]

Thanks for your information, Al.
It helps a lot!!

[AlArchie]

A little added info regarding the FPM.....it's probably not all that critical as Tormek also made a T-3 model with a 10" wheel turning at 120 RPM or about 315 FPM surface speed.

I'd still try to stay in that lower speed range, though.

Al.

[BobT]

If you are referring to the leather wheels like you can buy at Woodcraft and such, the package says "Do Not Exceed 650 RPM"
Bob

[xsailer]

Not saying I do things right but I have 8-10 inch leather covered mdf wheel I turn at around 1000RPM and I've not had any problems. I press very little against the leather and have compound on it. I don't stay long on the wheel either and check constantly for high temp on the blade.

[BobT]

I am sure the 650 RPM is a Product Liability concern. I can't imagine them coming apart at 1000 RPM (or even higher). I used to use those paper wheels at 3600 RPM. They never threw anything at me.

[AlArchie]

I doubt very much if there is a problem with those high speed wheels.....I use a 1750 RPM 6" felt wheel myself for an occasional power stropping and have never had a problem with overheating...it's durn near impossible to get a blade hot enough on a honing power strop to do damage unless you REALLY try. You have to get that blade to the point of the metal turning blue, and with cloth or leather strops, those things would be either smoking or blazing.
Having said that, I would think that on a purely engineering basis, the folks at Tormek have put some research into optimal speeds for both honeing and power stropping and have settled on that 90 RPM with a 10" wheel as optimal. In other words, that speed is plenty fast enough to get the job done and there is no need to go any faster. Faster won't hurt and slower will get the job done and more slowly, but they have determined what they feel is OPTIMAL.

Our club has a Tormek that I'm "sort of" in charge of and it works great. I also have four sharpening systems at my home, including now, one of those "see through" wheels you use from underneath. I have yet to try this one out, but it looks like it will also do a fine job of re-beveling my turning tools, etc.


Along with the 1750 felt and cloth wheel units I have a home made leather faced power strop with an 8" wheel turning at around 400 RPM. (or thereabouts) All of them work well! Simple as that.

Bottom line on my thinking is that any rotational speed from 60 to 3750 will work, if the wheel will stand the rotational forces. But judging from the engineering done by Tormek and their clones, 10" wheels with rotational speeds of from 60 RPM to 120 RPM are OPTIMAL.

Al

[xsailer]

I think the concern is the leather coming of the wheel not the wheel disintergrating. I've not had any problems at all.