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Hi George,

In my case, I drilled holes in the pully wheel that is used on the drum, and screwed the drum to the pully. I then drilled a small hole in the shaft where the pully set screw got in and thus secured everything in place. I did the same thing on the otherside of the drum, albeit the pully on that side was not couple to the motor.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Thanks. Did you leave any gaps between disks (or sets of disks)?

George

No. I stood the shaft upright, exactly how I have nowforgotten, but in a way that the first disk to go on would be straight (shaft plumb to the plane of the disk) and glue would not stick to whatever was holding it up. I put the first disk on with a little glue on the shaft where it would set. Then I put glue on the inside of the disk and up the shaft, set the next disk on and repeated. My drum is 25.5” (34 disks) wide so I had to work fairly quickly. After all the disks were on, I added several heavy weights to help clamp the last few disks (which didn’t have the benefit of the weight of the stack of disks). The end result was quite a lot of messy foam on the surface (easily removed when truing the drum) and no space between the disks. Thinking about it more, I may have done it in two sessions, I can’t remember for sure. I spun the drum on the sander and roughed it round then trued it to the table with sandpaper on the table. I have noticed 2 or three cracks where the MDF has split (not the glue lines) but they are so narrow that I don’t consider them to be a factor at all. So, over the span of 25.5 inches, it moved enough to open 2 or three (just wider than) hairline cracks. Plywood would probably move a bit more, but likely not enough to cause a glue-line failure between the drum and shaft. . .

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Wonderful. Thanks for the detailed explanation.

George

I finally have the thing almost finished and am trying to true up the drum. Something odd is going on and I'm getting a 0.01" to 0.015" variation every 90 degrees around the drum. Do you know how consistent your drum is around the circumference? I noticed that my motor moves about 1/8" over one drum rotation due to an inconsistent pulley I think (a new one is on order). I'm not sure if the vibration caused by the motor bouncing around is enough to cause the variations in my drum. Just curious if maybe I'm worrying over nothing.

George

That's true if the vac filter is clean, but using a shopvac with a drum sander will clog the filter pretty quickly. Strange as it may sound, a clogged filter has better efficiency at removing small particles, as long as it's still got adequate airflow. It's not as good as a real dust collectoin system, but I was suprised at how good my shopvac works with my sander.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

I trued up the drum on mine by spray-gluing a strip of 80 grit to the table and raising the table to the rotating drum. It worked like a charm.

My drum is 6" dia PVC pipe with five 3/4" disks glued to the shaft. I used PU glue for gluing down flooring.

Bob

Just my belief based on experience, but I think the best course of action is to start at foundation and work your way up. We all need different levels of precision, so I can't tell you what is acceptable for your needs.

Disconnect the belt when taking measurements for runout. Record all measurements.

1. Measure motor shaft first, then the driver sheave (pulley on the motor shaft).
If you are out of tolerance on the motor shaft, either the shaft is not straight, or your motor bearings are suspect. If the shaft is OK, but the runout at the sheave is unacceptable, then you know it's time for a better sheave.

2. Check the shaft for the drum.
Typically this is done before the drum is assembled to ensure straightness of the shaft itself, but you also want to check after the shaft is inserted into the bearings. If the shaft was straight to begin with, but shows excessive runout after insertion into the bearings, then either a) the bearings are at fault, or b) the fit between the bearing and shaft needs improved.

3. Driven sheave (pulley on the drum shaft).

4. The drum itself.

Don't overlook the belt. Often the right belt can alleviate inconsistencies between the driver half (motor and pulley) and the driven half (drum assembly and pulley).

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Always have plenty of sandpaper; it's rough out there!

They are VERY dusty to run. But a medium sized shop vac would probably be enough to operate it.

How wide is your sander? Mine is 20". I can't quite imagine PVC pipe working for that length sander. It must have been hard to slide the pipe over the disks if they're any kind of snug fit.

When I turn the drum by hand with the sandpaper underneath it will take down the high spots. I'm suspecting that the pulley I have where the belt rides high in one spot causing the motor to bounce a bit is setting up a vibration that is causing the problem. I suppose my wide drum (20") isn't helping. Even though it seems solid as a rock with a 1" cold rolled shaft it must be vibrating when turning at high speed.

George

What type of belt?
If the belt is riding erratically on the sheave, broken cords in the belt can cause that, but I wouldn't suspect the belt until the previous items in the chain checked out OK (motor shaft and sheave). BTW, broken cords are assuming that you're using a v-belt; obviously doesn't apply to the same degree if using a linkbelt.

As to the high spots on the drum, I don't know what materials you have used, to what dimensions, to what tolerances. Yes, you can (and should) true the drum, but it's sorta putting the cart before the horse if the items before the drum are not addressed.

I feel your pain, and finding the little gremlins can truly give you fits and send you off on a wild goose chase.
The last one I built ended up using a 1.5" TGP shaft; went with that because the initial CRS didn't meet standard. Thought I was getting a good price, but the initial shaft was not straight, and the diameter was a tad on the small side for the bearings being used, causing the shaft to run in an eccentric manner. And that's after I already had everything assembled and had trued the drum. Some new words were invented that day.

Determine cause of movement at the motor and take care of that, then work your way up through the belt. Once that area is satisfied, check the drum assembly, starting at the shaft/bearing. If the shaft does not rotate to your standards, then it will do no good to true the drum. Once you know the shaft is riding OK, then true the drum.

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Always have plenty of sandpaper; it's rough out there!

First of all, thanks much for taking the time to work with me. Hopefully this discussion will help someone else too.

I'm using a V belt. I'm pretty sure the belt isn't at fault. I shifted the belt around while keeping the pulley still and the high spot always occurs at the same spot on the pulley. A new one should be here soon.

Unfortunately it's too late to check much on the shaft. My gauge won't reach the shaft past the disks. The shaft is a very tight fit in the bearings. I had two extra bearings at my disposal to try and they didn't help.

I used MDF for the disks.

It seems that since I can't really measure anything about the shaft all I can do at this point is take care of the vibration caused by the bad pulley. If that fails I'm probably stuck with starting over with a new shaft - or looking for a used sander. I wish I had found your instructions before I started the build. In all the builds I saw on the web (at least a dozen) it seemed like everyone just slapped the disks on the shaft, trued up the drum and ended up with a perfect sander.

George

I disagree. A medium sized shop vac will pull about 150 cfm. Supermax recommends a minimum of 600 cfm for their 19/38 drum sander and to get good fine dust collection you need 800+ cfm at the machine. You would need a 3+ hp cyclone dust collector with 6" port to get 800 cfm at the machine. But at the very least you should get a 1.5 hp "hobbyist" dust collector with a 4" port (straight to the machine, will need to open up your port wider), run a short hose, and upgrade to a Wynn Env. canister filter, all while wearing a Niosh approved respirator until safe to remove. A shop vac will be inadequate to remove the fine harmful dust and your sander will mostly likely bog down with any but the lightest passes.

Hi George,
Did you use plain cold rolled steel, or the Turned, Ground, and Polished shafting? The TG &P is made to much tighter specs, and is really the only thing you should use for shafts...

To true up my wheel, I glued some sandpaper to some MDF and ran it through the machine. Worked great.

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Regards,
Phillip Patton

http://www.pattonblades.com

The bitterness of poor quality lingers long after the sweetness of low price has faded.

https://hoosierbladesmith.wordpress.com

I used cold rolled. Somebody else, who I thought he knew what he was talking about, said that was what I should get. If I have to make another one I'll try the TG&P.

I also tried to true up my drum just like you did. Did you happen to measure just how true your drum ended up?

My new pulley should be here soon. I'll report back if the decreased vibration allowed me to get rid of the high spots on the drum.

No, not really. My sander isn't very precise. For most things, it's ok, but I'd really like to get a "real" drum sander.

Mine sand things thinner on one side (I need to shim up one bearing) but this works great if I want to make a top thinner on the outside.

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Regards,
Phillip Patton

http://www.pattonblades.com

The bitterness of poor quality lingers long after the sweetness of low price has faded.

https://hoosierbladesmith.wordpress.com

I'm going to build a thickness sander and have located most materials on line (wood, hinges etc. will be easy locally).

Pillow blocks from Amazon

http://www.amazon.com/Bearing-UCP205-16 ... s_indust_5

T,G & P 1" steel rod from Speedy Metals

http://www.speedymetals.com/pc-1623-823 ... 0-001.aspx

Motor from Harbor Freight - Is 1/2 HP enough??

http://www.harborfreight.com/12-hp-gene ... 67839.html

I do not have a source for the pulleys. Where did you buy the pulleys? And is 2" at the motor and 5" at the disks the proper sizes?

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Thank You and Best To All

Looks like Grizzly has a NICE selection of motors. What HP is considered ideal to use with a thickness sander like Pat Hawley's design? And what RPM - 1725 or 3450?

http://www.grizzly.com/search/search.as ... 0050973296

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Thank You and Best To All

So I just built a drum sander as inspired by this string.
I have limited space in my shop so I incorporated the sander beneath my existing workbench. Works great!
Anyone kicking this idea around needs to know how easy it really is...not to mention the $1500 one saves with this approach as opposed to a commercial unit.

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Doug

Don't let fear or common sense stop you from trying to build something

My unit is 1/2 hp, 19" wide and it seems to be plenty of power for light passes. I have a 2" pulley on the drive shaft and a 5" pulley on the drum shaft...the speed seems comfortable coming off a motor turning at 1725 rpm.

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Doug

Don't let fear or common sense stop you from trying to build something

LOVE the idea of mounting under the work bench. Where'd you get the pulleys? Drum shaft size? Thanks.

It seems like the 2" and 5" are accepted sizes for the pulleys, slowing the rpms at the drum from the motor's 1725 rpm, but then accelerating the rpm's from the larger diameter of the drum.

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Thank You and Best To All

Re-size the pic to 800 pixels wide - seems to be a good size for forums. You'll need a photo editing program to do so but there's tons of free ones on line. Gimp and IrfanView are two that I use.

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Thank You and Best To All

For pulleys try furnace repair section of Lowes or HD. I used cold rolled 3/4" for shaft and would not do anything less for sure.

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Doug

Don't let fear or common sense stop you from trying to build something

I just finished mine. So far so good. Mine is 20" wide with a 1" shaft. I used an old 1/2" hp motor from Menards that works fine. The motor pulley is 4" and the shaft pulley is 5". After trying several pulleys I finally found a good cast iron one at Fastenall. It was only $16. Cheaper than crummy ones I tried first.

George