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17 posts 1 2

Belt Sander

#191622 by GeorgeM » Mon Jul 13, 2015 9:41 pm

Hi All

In Sawdust Session #12, Nick says that if the belt sander roller has a crown, take it and get it removed. Mine has a very slight crown. How important do you all feel the removal of this crown is?

Thanks
GeorgeM

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Re: Belt Sander

#191623 by algale » Mon Jul 13, 2015 9:46 pm

If your belt sander tracks correctly, I'd say it isn't important at all and don't mess with it.

Incidentally, my recollection is that Nick said that they used to crown both the upper and lower roller and now only crown one of them (which one I don't recall).

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Gale's Law: The bigger the woodworking project, the less the mistakes show in any photo taken far enough away to show the entire project!

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Re: Belt Sander

#191625 by billmayo » Mon Jul 13, 2015 11:08 pm

The drive drum surface is flat on later model belt sanders. The idler drum still has a crown on it and you still need to crown any new sanding belt to get better tracking. I machine the lower drive drum flat on any belt sander I rebuild. It does make tracking a lot better with the flat drive drum. I have been adding a zerk grease fitting in the upper idler drum so a pressure grease gun can be used to grease it. I find the idler drum shaft (expensive from Shopsmith) always will show wear from lack of grease which has harden over time and can bind the torsion spring.

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Re: Belt Sander

#191631 by GeorgeM » Tue Jul 14, 2015 9:03 am

billmayo wrote:The drive drum surface is flat on later model belt sanders. The idler drum still has a crown on it and you still need to crown any new sanding belt to get better tracking. I machine the lower drive drum flat on any belt sander I rebuild. It does make tracking a lot better with the flat drive drum. I have been adding a zerk grease fitting in the upper idler drum so a pressure grease gun can be used to grease it. I find the idler drum shaft (expensive from Shopsmith) always will show wear from lack of grease which has harden over time and can bind the torsion spring.



Hi

How do you crown a belt and could you show some detail regarding the zerk fitting?

Thanks
GeorgeM

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Re: Belt Sander

#191639 by billmayo » Tue Jul 14, 2015 12:43 pm

The crowning of the sanding belt is discussed under topic #7 "Crown the belt" on page 15 of the 6" Belt Sander Manual 555355. NOTE: Cloth-backed belts should be crowned when they are new and occasionally during their useful life. However, DO NOT crown paper-backed belts. Paper does not stretch as easily as cloth and the belt may tear or split.

I find almost all of the Idler Drum problems are from grease inside the drum getting hard. It will get to where you are unable to wind the spring the needed number of turns and/or the spring is restricted from applying the necessary pressure to keep the sanding belt tight. I find that if I remove the sanding belt, release the spring pressure and then can turn the tension knob 4 complete turns while hold the Idler Drum, then you are in great shape.

Years ago, I would drill a grease fitting hole through the hole in the middle of the Idler Drum and installed a grease fitting. I also drilled 3 holes in the center of the idler shaft (45) so grease could get to the spring (46). This way, I could use my grease gun to lubricate the Idler Drum when needed. I discussed this modification with Shopsmith QA in 2008 but they felt it was over kill due to the few reported problems in this area. I strongly believe that the Idler Drum shaft needs a method to grease it. All the Idler drum shafts I have reviewed have shown wear due to the grease hardening and no longer providing lubrication.

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There is a Sawdust Session video for rebuilding the belt sander. You need to keep track of the location of all the parts removed when disassembling the Idler Drum assembly. I use what I believe is a #10 threaded screw to pull the spring end out to where I can remove the roll pin and to install the roll pin when done lubricating.

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Re: Belt Sander

#191771 by GeorgeM » Fri Jul 17, 2015 9:43 pm

Hi

My belt sander is rather old. It's model # 505642, serial # 7515. My manual is # 84-3472 and it does not have a page 15, but I found crowning on page 3. Now my problem is that it does not automatically tension itself. I can not figure out how to get it to do that.

This is what should happen: ..."Automatic belt tensioning and tracking -- Just twist the Tensioning Knob until it clicks to release the tension for belt changes. Then, depress the knob release lever and everything snaps back to “normal”, automatically."... Except it doesn't. There is no snap back to "normal".

When I rotate the knob counterclockwise, the release lever does pop out. However, when I push the release lever back in all it does is allow me to manually turn the knob and increase tension. But there is no locking of the tension knob and it is possible to increase the tension to a point where it is so tight that the machine will not start. I can set the tension knob to any amount of tension but there is no way to keep it at that level of tension. There must be some way to adjust it so that the automatic tensioning works, but I have been unable to find out how to do that.

Any help would be appreciated.


Thanks
GeorgeM

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Re: Belt Sander

#191774 by billmayo » Fri Jul 17, 2015 11:53 pm

I find this often happens when the grease harden in the idler drum. You rotate tension knob CCW while holding the idler drum and the knob latch should click and hold after each rotation. I do 4 rotations and install the belt. I adjust the tracking screws to level the idler drum to where I can just slide the sanding belt onto the idler drum before pressing the knob latch to release the spring tension. There is a sawdust session #12 Tuning up the Shopsmith Belt Sander on rebuilding the belt sander that is excellent if you decide to disassemble the belt sander. http://www.shopsmithacademy.com/Sawdust_Sessions.htm

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Re: Belt Sander

#191809 by GeorgeM » Sat Jul 18, 2015 9:51 pm

billmayo wrote:I find this often happens when the grease harden in the idler drum. You rotate tension knob CCW while holding the idler drum and the knob latch should click and hold after each rotation. I do 4 rotations and install the belt. I adjust the tracking screws to level the idler drum to where I can just slide the sanding belt onto the idler drum before pressing the knob latch to release the spring tension. There is a sawdust session #12 Tuning up the Shopsmith Belt Sander on rebuilding the belt sander that is excellent if you decide to disassemble the belt sander. http://www.shopsmithacademy.com/Sawdust_Sessions.htm



Thanks Bill, I'll try that when I get back home

GeorgeM

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Re: Belt Sander

#191918 by GeorgeM » Mon Jul 20, 2015 10:32 pm

billmayo wrote:I find this often happens when the grease harden in the idler drum. You rotate tension knob CCW while holding the idler drum and the knob latch should click and hold after each rotation. I do 4 rotations and install the belt. I adjust the tracking screws to level the idler drum to where I can just slide the sanding belt onto the idler drum before pressing the knob latch to release the spring tension. There is a sawdust session #12 Tuning up the Shopsmith Belt Sander on rebuilding the belt sander that is excellent if you decide to disassemble the belt sander. http://www.shopsmithacademy.com/Sawdust_Sessions.htm


Hi Bill

I was able to set the tension by turning the knob four turns counterclockwise. Now if I understand you correctly what I need to do is put the belt back on, and then depress the detent on the knob. What I'm not sure of is exactly what happens next. Am I supposed to hold onto the knob and the internal spring will then set the tension when I press the detent? Or do I press the detent and then let go of the knob and allow the knob to turn thus setting the tension? What exactly is the correct method of setting the tension?

Either way I am in trouble as the knob will not travel by itself. It looks like I will have to take it apart in order to grease the shaft where the bearings ride. I have viewed the video several times but I'm still not looking forward to doing that job.

Regards
George

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Re: Belt Sander

#191924 by JPG » Mon Jul 20, 2015 11:32 pm

Courtesy of Reible

belt sander tension adj.jpg
belt sander tension adj.jpg (73.63 KiB) Viewed 2807 times

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