Measurements off of bearing-style Strip Sander Idlers

[nuhobby]

Greetings,

I have my brand-new Strip-Sander which has, as noted in some prior threads, the plastic idler-wheels rather than ball-bearing metal idler-wheels.

While I'm OK so far, my "annual minus nu" personality may pursue fabricating some metal idlers with bearings.

Can anyone with the metal wheels & bearings confirm for me:
- The outer diameter of the wheels?
- Any crowning present?

Thanks in Advance,

[SDSSmith]

I can measure the diameter later today if no one else comes forward with the info. I know the steel idlers on my sander have a slight crown to them and I would expect the diameter to be the same as the newer version.

Before fabricating, I would call and check to see if Shopsmith still sells item 516399 listed for sanders prior to 1993 and if they are the steel idler wheel.

[JPG]

I can measure the diameter later today if no one else comes forward with the info. I know the steel idlers on my sander have a slight crown to them and I would expect the diameter to be the same as the newer version.

Before fabricating, I would call and check to see if Shopsmith still sells item 516399 listed for sanders prior to 1993 and if they are the steel idler wheel.

That would be great if so, but I think it has been determined previously that they are 'gone'.





If they are not, and it is stated here, I predict they will be 'gone' in a very short period of time.

[reible]

Hi,

I've got two machines with metal wheels and can get some measurements but I forgot which of the wheels were changed to plastic... If it is the idlers as was suggested by the one post then I can answer that right now.

First I have one that has no rubber banding on it and a second that does. I have had no problem with belts coming off so maybe that doesn't really matter. I can not say the bare wheels once had the banding or if they came standard that way.

The bare metal wheel measures 1.87" at the center and as close as I could get to the edge it was 1.825". The wheel with the tire measures 1.99" with a little pressure applied.

Some pictures of what they look like follow.

[ATTACH]14786[/ATTACH]

[ATTACH]14787[/ATTACH]

Ed

[nuhobby]

Gents,

Thanks for your help! It does look like the dimensions/shapes were kept the same when they went to the plastic wheels. I'll report back one of these days after I do some tinkering.

[JPG]

Hi,

I've got two machines with metal wheels and can get some measurements but I forgot which of the wheels were changed to plastic... If it is the idlers as was suggested by the one post then I can answer that right now.

First I have one that has no rubber banding on it and a second that does. I have had no problem with belts coming off so maybe that doesn't really matter. I can not say the bare wheels once had the banding or if they came standard that way.

The bare metal wheel measures 1.87" at the center and as close as I could get to the edge it was 1.825". The wheel with the tire measures 1.99" with a little pressure applied.

Some pictures of what they look like follow.

[ATTACH]14786[/ATTACH]

[ATTACH]14787[/ATTACH]

Ed

I wonder if the rubber sleeved ones are intended to be the idler that the abrasive side of the belt runs on when doing 'inside' sanding. I worry about wear on that pulley. I do not envision the plastic ones lasting very long under that scenario. I do not recall anything in my manual referring to rubber sleeves.

I will be looking for a bicycle tire inner tube of about the same size(1 3/4) if they exist!;)

[nuhobby]

An interim update....

I thought about this and there were a few aspects to consider as different between the current-production plastic idler-wheels and the prior metal idler-wheels. Such as (1.) Mass/Rotational Inertia, (2.) Concentricity, (3.) Machined profile including crowning or lack of, (4.) Material hardness/durability, (5.) Bearing type.

I decided to save some energy and try a step to improve points (1.) thru (4.) with a minimal investment. I've increased mass/inertia/hardness by using some extremely hard persimmon wood I had on hand. It is well-machined on the lathe to a gentle crown as a starting point. For concentricity, I nailed one wheel exactly, and the 2nd wheel I should be able to improve during the glue-up between brass tubes and wheels. I'm using some brass tube which appears to be just about the same ID as the factory wheel's bushing.

Regarding point (5.), a bushing may be sufficient if I keep it lubed. Accounts of plastic wheels wearing out may be caused in large part by points (1.) thru (4.). A lazy man's speculation.....

A photo is attached. It will be a few days before I get to finishing my wheels and trying them. IF I'm successful, I have enough of this particular brass tubing stock to share some with those who'd be interested.

[ATTACH]14897[/ATTACH]

[nuhobby]

I don't think anybody was hanging on hearing more on this thread, but here's what I found:

- The wood idlers I made were louder than the Shopsmith plastic idlers. Could have been a slight dimensional mis-match in the brass-rod 'bushings' I used. Also the mass/density of the hardwood seemed to audibly "ring" more than the plastic material.

- Having a deliberately "crowned" idler-wheel was OK for the usual strip-sanding idler (near the rear of the machine) but was a 'bust' for the alternate setup of re-threading and sanding inside a work-piece. Having a crowned idler in that configuration seemed to make the strip-sandpaper walk off the wheels.

At the end of the day, I really don't rethread and sand inside holes much (if ever), so with the factory plastic wheels I'm really satisfied after all. I lube them with some nice light grease that I use on bicycle repairs.

P.S. It's good to make projects rather than tinker with machines sometimes.