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Question about DIY Drum Sanders

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Forum topic by Dallas posted 01-31-2012 08:07 PM 2191 views 1 time favorited 5 replies Add to Favorites Watch
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Dallas

2905 posts in 1140 days


01-31-2012 08:07 PM

I have been watching the various threads on homemade drum sanders and have been seriously considering building one for myself.

It seems that some people use a lathe to turn layers of plywood (I think), to make the drum.

My problem is that I don’t have a lathe and my ability to cut repeatable circles diminishes after about 2. Even when using my DeWalt holesaw there is enough variance that I doubt I would have accurate, useful rounds.

My thought was to use something else, like maybe some 4” or 6” PVC with plywood rounds filling it and Gorilla glue expanded into the nooks and crannies to hold it tightly.

I had another thought about using some steel well casing I have laying around, either 6” or 8” and using the plywood rounds as end pieces to use for mounting the casing. I know that the casing is heavy, and wonder if it’s too much for a 1 1/2 HP motor with a pulley system set up for about 1100 rpm.

Would either of these be a good idea?

Thanks!

Dallas

-- Improvise.... Adapt...... Overcome!


5 replies so far

View crank49's profile

crank49

3421 posts in 1623 days


#1 posted 01-31-2012 08:39 PM

From an engineering point of view I see much more to fear from the shaft and bearing loads a steel pipe spinning at 1100 RPM will generate than the load on the motor.

Any reason you want to make it 6” or 8” other than that’s what you have on hand? That’s going to give 2300 SFPM (surface feet per minute) at 1100 RPM. I was thinking most sanders keep it below 1400 SFPM.

Also, the motor load will come from the large diameter of the drum, regardless of the material the drum is made from.

I would use MDF and wouldn’t go more than 4”, or possibly 5” diameter if I was looking to build one myself. Well, actually I do plan to build one myself, but it’s way down a long list.

As for making the disks round, they don’t have to start out perfect. Cut them with a hole saw or a jig saw or whatever and mount on the shaft. Then, with the drive hooked up, spin the drum against a rasp and then very coarse sanding block and work it round gradually. I have even done this type work without any drive hooked up and used a belt sander held by hand at a skewed angle to the drum. The sander will spin the drum. This is not as hard as it sounds.

One other thing. Gorilla glue, although it’s mighty handy stuff, will be too brittle in this application. It has very low shear strength. Use the best epoxy you can get.

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

View Viking's profile

Viking

857 posts in 1848 days


#2 posted 01-31-2012 08:51 PM

Dallas;

Another issue will the steel pipe is that it would most likely be anywhere close to being balanced which would also be hard on your motor.

Crank has the right idea.

Good luck.

-- Rick Gustafson - Lost Creek Ranch - Colorado County, Texas

View Radu's profile

Radu

299 posts in 1696 days


#3 posted 01-31-2012 08:55 PM

Here is link to a video on how to cut a circle on a table saw (I’m sure there are a lot more out there)
http://www.videojug.com/film/how-to-cut-a-circle-on-a-table-saw-2
Though, I don’t know how small of a circle can be safely cut this way. I think 5” diameter is on the small side. A similar jig could be used on the band saw.

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Dallas

2905 posts in 1140 days


#4 posted 01-31-2012 09:38 PM

Wayy Coooollllll as my son says.

Yes, the only reason to make it 6” or 8” would be because it’s available, cheap, strong and extremely concentric. (Oil and gas drillers can’t use pipe that isn’t almost perfectly round).
Another thought on the well casing, after a bit of time thinking about it is, I have a 12.5 Kw air cooled Onan generator. It works but it’s big, heavy and really noisy, aside from the fact that getting parts or information from Onan is almost impossible, It has a nice flywheel and a great squirrel cage fan.
I could remove the fan for use in the dust collection department, and use the fly wheel on one end of the drum sander to help balance the weight of the drum itself. I would have it welded to the drum and another piece welded on the other end and balanced by the local machine shop to give me a true round surface to work with.

The idea of so much weight is that if you’ve ever used an under powered bench grinder or other spinning tool, it’s a real PITA to have to stop and wait for the speed to come back up again if you apply too much pressure to the work piece.

I will agree with the 1400 SFPM as I may have misread what I saw before. I was under the impression that the faster it spun, the easier it was on the unit as a whole. Since I’m not an engineer, I’m asking here, especially from my fellow LJ’ers with engineering back grounds.
I could always reset the sizes of the pulleys to give the best performance.
On this Idea I would be using a 1 1/4” mandrel which should be able to handle the power and torque involved, (I hope? I’ll be checking further to see if that is a good choice although it is another piece I already have).

I have pretty much dismissed the PVC idea because when PVC gets warm it has a tendency to deform, and even a little deformation doesn’t sound like a good thing.

Keep the ideas coming folks, I’m all ears! (My mom said my ears were born first and I grew on six months later).

-- Improvise.... Adapt...... Overcome!

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Grandpa

3130 posts in 1328 days


#5 posted 02-01-2012 03:47 AM

http://lumberjocks.com/projects/13699
I think somewhere around 5 inches is what most people are using. This one is 5.5”

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