# Building Thickness sander - Drum Question



## wildbill001 (Mar 2, 2011)

Building a thickness sander based on designs I've seen here and on the 'net'. One thing I rarely, if ever, see mentioned is attachment of the wooddisk to the shaft. Some folks have said that the epoxy/glue they used to glue-up the drum was sufficient to hold to the shaft. Others don't mention anything about it.

I have a 5/8" shaft, with 5" MDF disks. The disks move easily along the shaft after drilling a 5/8" hole. I can't help but wonder if I need to somehow "pin" the drum to the shaft to keep it from free-wheeling.

So for those who have gone down this road, How did you attach the disks to the shaft ?

TIA

Bill


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## Bertha (Jan 10, 2011)

I considered making one of these. You could grind a flat into the shaft to engage a long machine screw inserted from the perimeter of the disk. You could also thread the axle and capture the disks with nuts. I was worried about exactly what you're worrying about; I applaud you for going for it!


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## crank49 (Apr 7, 2010)

Caution! A 5/8" dia shaft is pretty small for the mass you are wanting to spin. across the length most drums need to be; I'm assuming over 20" or so. If it was a metal drum, no problem; the drum itself adds rigidity. Not so much so with wood or MDF. Then, to drill a 1/4" hole through this shaft in three places; I don't think I want to be standing in the line of fire when this thing revs up.

From what I have read, most of these drums use 5/8" dia. shaft for a 16" to 18" drum. One builder said if he were doing it over, or going any longer, he would use 1", but didn't say why.

The link below here is another LJ who did this. His, and 3 or 4 other threads I read, indicate they only attach the drum disks to the shaft with epoxy.
http://www.rockslide.org/drum%20sander.html


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## Bertha (Jan 10, 2011)

Good point, Cr1. How are the other guys around here doing it?


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## wildbill001 (Mar 2, 2011)

Let me clarify. I'm planning on a width of 12", possibly shorter but certainly no longer.

Bill


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## crank49 (Apr 7, 2010)

Well, for a 12" drum width, based on other projects I have read, you should be okay.

As far as attaching the disks to the shaft, the epoxy will absolutely adhere to the ID of the disks. 
You might want to rough up the surface of the shaft in the area to be glued. Also, you want to be absolutely sure and clean all traces of oil off the shaft before installing in the disks. I have had good results using lacquer thinner as a solvent for this purpose, then follow with acetone.

Good luck, and keep us posted.


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## SASmith (Mar 22, 2010)

This is how it is done in Shopnotes #86 Vol. 15.


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## Bertha (Jan 10, 2011)

Thanks SASmith, I'm trying to imagine what that locking wedge does.


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## SASmith (Mar 22, 2010)

It is to hold the end(s) of the sandpaper.


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## wildbill001 (Mar 2, 2011)

Thanks SASmith for the diagram. That's actually pretty much how I envisioned it.


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## crank49 (Apr 7, 2010)

Ya'll did notice that the ShopNotes version uses a 3/4" shaft? and 3/16" pins?


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## Bertha (Jan 10, 2011)

Cr1, I was planning on 1" just because the pillowblocks are easy to come by. I tend to agree with Cr1 that I'm probably underestimating the forces generated at the moment arm. I imagine 12 inches of sandpaper meeting wood at relatively high speed could generate a lot of force. I can see the axle twisting off at the pin points. I'm no engineer but I do break a lot of stuff.


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## GMotichka (Oct 31, 2010)

I used a 1" shaft for mine. It also uses MDF disks, but has a 26" capacity, and use the pin system seen in the Shopnotes article. The wedges are to anchor the sandpaper. Instead I used the conversion kit sold by Jet that uses Hook and Loop.
It works well, but if I did it again, I would use an aluminum cylinder rather than MDF.


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## Bertha (Jan 10, 2011)

Thanks to all for explaining the wedge to me. I'll have to look into this JET conversion.


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## GMotichka (Oct 31, 2010)

cr1,
You would have to either turn some aluminum blanks into hubs, or have someone do it for you. The LJ who helped me (Johnz) could do it. He turned the aluminum hubs for my transport rollers. I also believe TomT used an aluminum cylinder for his drum.


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## BritBoxmaker (Feb 1, 2010)

I used PVA between the discs and Epoxy to glue them to the shaft. One year of constant use later its still intact.


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## wildbill001 (Mar 2, 2011)

What I have ended up doing was to drill the shaft for a 3/16" steel rod at each end, 90deg difference. I routed a channel in two disks to accept that rod as a "lock". I was able to cut a small piece off the shaft which I cleaned completely. As a test, I cut some small blocks, drilled them and glued them together with TB II using a lot of glue close to the shaft. Let it dry for a good 24-36 hrs. I couldn't move them. SO, I glued up the disks onto the shaft using the 3/16" steel pin at each end. Let it dry for 2 days.

At that point, I mounted the shaft onto its frame, placed a board across the frame and powered it up. I then took a cheap bowl-gouge that I use for roughing on the lathe and using the board I layed parallel to the "drum" proceeded to start scraping the dried glue off (there was a lot of it). At one point the gouge caught and grabbed the drum, stopping it dead (the belt just slipped on the pulley). Shut everything down and checked the drum. Still tight so I powered up and finished removing all the old glue. Everything seems to be holding just fine.

Once I get back home, I plan to true the drum to the table. Then mount some 80 or 100 grit and take it all for a test drive.

Bill


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