Author Topic: Belt Sander Tweak  (Read 8615 times)

Offline sparky961

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Belt Sander Tweak
« on: December 23, 2012, 11:49:46 PM »
I had a project that would go a lot quicker with a bench top belt sander.  A quick Kijiji search showed that there were quite a few of the Canadian Tire 4 inch combination belt/disc sanders for sale near me.  The majority of the ads claimed they were like new, and they were selling them for about half of Canadian Tire's SALE price (so about $40 CAD).

This is the Menard's version of the same thing because it was a better picture and I hadn't taken any showing the whole thing.


I ended up picking one up for $30, and considering the heavy cast base on the machine I was pretty happy with the purchase.  Now, the guy I bought it from did show it working, but since he couldn't figure out how the belt tracking worked, I didn't want him to demo it any further (in both senses of the word - demolish/demonstrate).  From what I could tell, everything was in order so I handed over the cash and headed home with my new toy.

When I stated playing with it at home I noticed there was a surprising amount of vibration of the belt "arm".  After a bit of investigation, I found that with the belt tilted in the upright position, turning the belt by hand resulted in the top moving sideways by almost 1/4"!  It smoothed out a bit once running, but this was definitely the cause of the vibration.

I started to take things apart, being careful to pay attention so that things would go back together when I was done.  I put an indicator on a bunch of different parts, trying to track down what wasn't right.  Starting at the belt drive roller, I moved my way back to the timing pulley inside the belt cover.  This is where I found the problem.  Slowly rotating it by hand, I found that the upper pulley (gear, if you prefer) measured 0.015" TIR.  The bottom one was almost the same amount out.



I decided to bore & sleeve them, re-machining the hole on center with the OD.  My first challenge was taking the screw out that held the pulley on.  It seemed like it was extremely tight and had a gallon of loctite holding it from turning.  I stripped the Phillips head after applying almost enough force to snap it, and half-way through drilling it out it started to unscrew.... the wrong way.  Yes, it was a left-hand thread.  :doh:



So after removing the bottom one (hey, that came out pretty easily when you turn it the correct direction!) it was off to the lathe to bore out.  The upper had a 12mm hole and the lower was 13mm.  I decided to bore them both out to 14mm for simplicity of setup.





Since they're cast iron, the machining was very easy.  When I had a nice 14mm hole, I turned down a shaft to a light press fit and loctited them both onto the shaft.  I've had this huge bottle for years, and there will probably still be some left to pass on when I'm gone.



I'm not sure how long this is supposed to take to set, but since there was a bit of a press fit and I was taking light cuts I wasn't too worried about the sleeve coming out.  After cutting them off with the band saw, I drilled and bored to size, being very careful not to go over.  I made up a gauge rod to check the fit along the way.

Back to the lathe for facing and drilling.



A bit more work cross drilling and tapping for grub screws, and everything is ready to go back together.



If you have one of these sanders and it shakes all over the place, you might want to consider this fix.  When I was done, I re-checked the pulleys and smiled when I saw that they were both within 0.001" TIR.  The whole thing runs much smoother and quieter now.  All of this took only a few hours tonight (not that I would have minded it taking longer).  When I was done, I was reminded of why I like having the capability to make and modify parts.

Rob.Wilson

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Re: Belt Sander Tweak
« Reply #1 on: December 24, 2012, 04:18:04 AM »
Very well  done post Sparky  :clap: :clap: :clap:

Good to read you made up a gauge to check your pulley bores  :dremel:


Rob

Offline Meldonmech

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Re: Belt Sander Tweak
« Reply #2 on: January 09, 2013, 05:22:34 AM »
Hi Rob,
                    Just come across this mod, a neat fix. Worth doing even if the machine is running ok.

                                                                             Cheer up  David

Offline modeng200023

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Re: Belt Sander Tweak
« Reply #3 on: January 09, 2013, 10:50:31 AM »
I have one of these belt/disc sanders thought it was marketed under a different name. On powering it up it started to walk across the bench. The vibration was really bad. Inspection revealed the disc for the circular sanding sheets was a long way out of balance. The central hole that was keyed to the shaft was not at right angles to the disc face so that when originally machined one edge of the disc  ended up thicker than the opposite edge.

Fortunately there was enough thickness in the disc to machine the front face true to the central hole and then all was well.

I did check with the supplier for a replacement disc but all those I was shown were just as bad!

John

Offline sparky961

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Re: Belt Sander Tweak
« Reply #4 on: January 10, 2013, 01:10:40 AM »
So far mine's been sitting pretty still on the bench in the same place, but I'll be certain to check how that part of it is running now too.

When I buy a used machine, I always assume that I'll have to repair and tweak a few things before it runs the way I want it to.  Actually, that's 90% of the fun of getting a new machine for me.

For new machines though, I'm thoroughly disappointed when the manufacturer can't be bothered to make it right the first time around.  It seems that just as the Chinese metalworking tools are purchased as a "kit" to finish off yourself, so are other power tools like this.

Aren't you glad you can do something about it yourself though? :) It thoroughly satisfies me.

-Sparky

Offline Fredbare

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Re: Belt Sander Tweak
« Reply #5 on: January 10, 2013, 06:28:21 PM »
Thanks for sharing

John

Offline Deko

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Re: Belt Sander Tweak
« Reply #6 on: January 11, 2013, 04:52:00 AM »
I have one of these and happy to say no problems so far, however "men in sheds" have one and i had to fix that about a month ago.
The bearing behind the pully had locked up solid and worn the 12mm shaft down to 6mm !!!!! so i had to make a new shaft.  A week later they broke the switch  :palm:

Cheers Dek.