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Thickness Sander

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Blog entry by Bob, Oregon posted 1200 days ago 7539 reads 46 times favorited 18 comments Add to Favorites Watch

There were a few questions about the sander so I thought I’d answer them here.

Condor1 & Blake:

Yes, I simply push the stock under the drum freehand on a sled. The sled is nothing more than a piece of plywood with a sacrificial little wedge-shaped fence that is tapped into a saw kerf at the operator end. That keeps the drum from trying to spit the wood back at you. (By the way, I have found that the same safety rule for table saws applies to this bugger…stay to one side – out of the line of fire – in case of kickback.) The drum turns so that it is working against you as you push. Since you won’t take very much off on a pass, this proves to be very workable. The drum is 3” in diameter. My motor runs @ 3450 rpm and I used a 2:1 pulley ratio to step the drum rpm down to somewhere in the vicinity of 1725. So far I have only used 120 grit paper on the drum and that has proven to be a very workable grit. It leaves an amazingly smooth finish, even on extremely thin (.031 or 1/32”) strips that I have milled out (of ebony, even!) for my ship modeling.

This is a view of the “back” of the sander and the coarse adjustment part. There is a 1/2” X 1/16” aluminum strip that runs vertically between the stationary base and the moving (table) support to keep the table support aligned. It is fixed (epoxied) in a slot in the fixed base and it runs free in a groove cut in the moving table support. It is just visible at bottom-right next to the cove-shaped cutout. The knobs have threaded studs that engage blind nuts on the inside of the base. Almost all of this hardware came from Reid Supply, which has a fabulous selection of goodies.

Here is the fine adjustment. The rod is 3/8 X 16 threaded rod from the local Ace Hardware. The adjustment knob is a “Quick-Acting” knob from Reid (p/n QK-3). It has a threaded, oblong hole through the center that allows you to tip the knob one way and it releases from the thread. Tip it back the other way and it engages. I made the little table that supports the knob by designing it in my head as I cut. Nothing fancy here. It’s maple.

This is the pivot arrangement between the fine-adjustment rod and the underside of the table. A couple of gate barrel bolt assemblies (Ace Hardware – brass) were dismantled to accomplish this. The only reason I needed two assemblies was because I needed two of the sockets. I drove the knob out of one of the barrel bolts and cut it to length. Then I ground the 3/-16 rod down to a place where it would press-fit into the hole in the barrel bolt and finally I soldered the joint.

And yes, Blake, I think we definitely looked at the same website. I wonder what happened to it?? There’s another one here that has similar thoughts.

Mark:

The pressure to feed the wood through is entirely dependent on how much you try to sand off in a pass. Taking off .002 takes very little pressure; taking off 1/32 requires considerably more.

Oh, by the way…Sandy…about 25 miles west of Mt. Hood. Where are you?

Jeremy:

After I turned the drum on the lathe, I assembled the sander. Then I stuck a sheet of 80 grit sandpaper to a piece of 3/4 MDF and ran it back and forth on the table under the drum. This does a final “squaring” of the drum with the table. I suppose it might be possible to completely turn the drum this way once you got it cut to an octagonal shape, but it would probably prove to be a long and tedious process.

Steve:

The motor is simply mounted on a 3/4” BB plate that is hinged at one end and there is an arrangement at the other end similar to the underside of the table fine adjustment – for adjusting the tension on the belt. Only I just used a couple of washers, a wingnut and nuts on either side since belt adjustment wouldn’t happen very often. (See below)

Any other questions? I’ll try to answer. I built this a couple of years ago and the ol’ memory ain’t what it used to be (if it ever was!)

And yes, to address the obvious: I suppose you could build a guard to put over the belt/pulleys if you so desire. I am the only one who ever gets near this thing (no kids in the house) and I stand on the side opposite the belt when I’m using it, so I am not terribly concerned.

-- 73, Bob



18 comments so far

View sras's profile

sras

3611 posts in 1631 days


#1 posted 1200 days ago

This is a really nice addition to your project posting! I appreciate the extra detail.

-- Steve - Impatience is Expensive

View Blake's profile

Blake

3432 posts in 2376 days


#2 posted 1200 days ago

WOW, Bob, that “course adjustment” feature is great. I wish I had thought of that. My table is fixed by the hinge in the back which limits the height to about 2.5 or 3”. I envy your ability to sand railroad ties, they are a great source of recycled lumber as long as you are pretty sure there won’t be any trains using that track for a while.

Actually there are times when I wish I could send a small box through my sander to level out the top or bottom so the lid sits flat. Anyway nice job on the sander and thanks for the extra photos.

-- Happy woodworking! http://www.openarmsphotography.com

View rweitz's profile

rweitz

89 posts in 1580 days


#3 posted 1200 days ago

I was not the one to ask the question, but always notice when someone else is from Oregon- go Ducks!
I’m over near Tigard by the way, close to I-5 & 217.

Also always looking at drum sanders on LJ and this looks like a nice one!

-- You cannot build a reputation on what you are going to do. - Henry Ford

View Eagle1's profile

Eagle1

2060 posts in 1567 days


#4 posted 1200 days ago

Nice piece of equipment. I might have to try to build one of these some day.

-- Tim, Missouri ....Inside every older person is a younger person wondering what the heck happened

View BigTiny's profile

BigTiny

1664 posts in 1390 days


#5 posted 1200 days ago

This is something high on my to do list, and yours has some great ideas. Consider them stolen! ;)

-- The nicer the nice, the higher the price!

View Furnitude's profile

Furnitude

292 posts in 2009 days


#6 posted 1194 days ago

This is an awesome machine! My questions are 1) where did you get the pulleys? and 2) what are the mounts that the drum (and the threaded rod and bearing) sit inside and where did you get those?

Thanks so much!

-- Mitch, http://furnitude.blogspot.com

View Bob, Oregon's profile

Bob, Oregon

90 posts in 1894 days


#7 posted 1194 days ago

Hi Mitch,

The bearings are pillow block bearings and they came from an outfit called The Surplus Center. The shaft is not a threaded rod, but rather a piece of plain steel rod (1/2”). There are numerous sources on the Internet and there may be some in your local area as well. I got mine from a buddy who had some left over from another project. I drilled the rod in two places about 2” from either end of the drum and inserted steel dowel pins to help prevent the shaft wanting to spin inside of the drum, which is made of laminated oak boards. I routed a groove in both halves of the drum for the shaft to rest in using a 1/2” cove bit. I roughed up the rod with a file and then epoxied the whole thing together, using LOTS of epoxy to make sure that everything was bonded and there were no air gaps.

The dowel pins came from Fastenal, primarily because the company has a local outlet in my home town (a fact that never ceases to amaze me because my home town has about 8000 residents!) The pulleys came from the Surplus Center as well. The rod needed a bit of filing to get both the pulleys and the bearings to fit. I made a cobbled-together rig on my wood lathe using a collet on the drive end and a simple wooden V-block clamped to the tool rest to support the out end.

Then I was able to use a mill smooth file to dress the rod down to the point where it would fit snugly into the bearings and pulleys. It seems these rods (at least the ones that normal people can afford) are not precisely the size that is stated. Mine were a bit oversized. I don’t own a metal lathe so I have to make do with what I have.

-- 73, Bob

View Furnitude's profile

Furnitude

292 posts in 2009 days


#8 posted 1193 days ago

Bob, thanks so much for the great information and photos. You documented your process very well. That makes it very helpful for those of us who aspire to making something this cool. Thanks again!

-- Mitch, http://furnitude.blogspot.com

View Bob, Oregon's profile

Bob, Oregon

90 posts in 1894 days


#9 posted 1193 days ago

One additional thought: Wiring.

If you look at the second picture you’ll see the on-off switch and a couple of outlets next to it. I wired this up so that the bottom outlet (as well as the sander motor) is controlled by the switch and the top outlet is hot full-time. I plug my shop-vac into the bottom outlet so that the vacuum comes on at the same time that the sander is turned on. (Keeps me from having to listen to the shop-vac howl any more than is necessary!) The full-time outlet is there in case I decide to figure out a way to add an articulated desk lamp to the thing, although to date I have not really had the need for additional lighting.

And by the way…wear ear protection. The combination of the sander and the shop-vac is overwhelming.

-- 73, Bob

View tdv's profile

tdv

1114 posts in 1572 days


#10 posted 1193 days ago

Bob That’s a great blog & an excellent machine I have made a surface sander but I like your design just wondering if I can incorporate your design & mount a table above something for me to ponder. By the way I built a guard for the drivebelt with bendy ply & some 18mm scraps I don’t know if you have built a guard yet but you can check it out it works fine, & spinning belts & pulleys don’t take prisoners
Thanks again for the great blog
Trevor

-- God created wood that we may create. Trevor East Yorkshire UK

View Bob, Oregon's profile

Bob, Oregon

90 posts in 1894 days


#11 posted 1192 days ago

Hi Mafe,

You can see how I joined the sides together around the shaft in the photo in my blog on this sander. I used plain ol’ 3/4” oak from HD. I had to plane a plank on each side down a bit as I recall, so that the glued-up dimensions would be a bit over 3 1/2” square. I then ripped all four sides down so that they were about 3 1/4” square. This got everything consistent and eliminated the ragged edges and glue squeeze-out. Then I made a simple sled so that I could trim off the corners on the table saw and produce an octagonal shape around the shaft.

Then I had to invent a sort of “Rube Goldberg” arrangement using a collet to spin the shaft and using the actual pillow block bearing, set up on some appropriately-sized wood blocks with shims and clamped to the lathe bed, to support the out end. I also put a small wood block between the tailstock dead center and the end of the shaft to keep everything under control.

Then it was a simple matter of turning the drum down to about 3 1/8” diameter. As I said earlier, when I got the whole sander assembled, I glued a sheet of 80 grit sandpaper to a piece of 3/4” MDF and ran that back and forth under the spinning (bare wood) drum. That trued the drum to the table.

So I guess the answer to your question is that since I used the steel shaft as a mandrel when turning, that automatically made the wood drum concentric with the shaft.

-- 73, Bob

View Bob, Oregon's profile

Bob, Oregon

90 posts in 1894 days


#12 posted 1192 days ago

Hi Mafe,

You can see how I joined the sides together around the shaft in the photo in my blog on this sander. I used plain ol’ 3/4” oak from HD. I had to plane a plank on each side down a bit as I recall, so that the glued-up dimensions would be a bit over 3 1/2” square. I then ripped all four sides down so that they were about 3 1/4” square. This got everything consistent and eliminated the ragged edges and glue squeeze-out. Then I made a simple sled so that I could trim off the corners on the table saw and produce an octagonal shape around the shaft.

Then I had to invent a sort of “Rube Goldberg” arrangement using a collet to spin the shaft and using the actual pillow block bearing, set up on some appropriately-sized wood blocks with shims and clamped to the lathe bed, to support the out end. I also put a small wood block between the tailstock dead center and the end of the shaft to keep everything under control.

Then it was a simple matter of turning the drum down to about 3 1/8” diameter. As I said earlier, when I got the whole sander assembled, I glued a sheet of 80 grit sandpaper to a piece of 3/4” MDF and ran that back and forth under the spinning (bare wood) drum. That trued the drum to the table.

So I guess the answer to your question is that since I used the steel shaft as a mandrel when turning, that automatically made the wood drum concentric with the shaft.

-- 73, Bob

View Bob, Oregon's profile

Bob, Oregon

90 posts in 1894 days


#13 posted 1192 days ago

Don’t know how I got two of the same posts in there, but maybe a moderator could delete one for me?? (I can’t figure out how to do that!)

-- 73, Bob

View tyka's profile

tyka

140 posts in 1195 days


#14 posted 1171 days ago

Good work Bob. Great idea for the back adjustment. I don’t have railroad ties around but a large opening should be good to sand small boxes :-) Thanks for sharing and for all the information.

-- Paul, Plantagenet, Ontario

View stiletta's profile

stiletta

23 posts in 1715 days


#15 posted 1157 days ago

I`m impressed with the way you are able to make that with woodworking equipment. How you trued up the drum to the table, sure is a clever idea.

The advantage of wood construction is that it absorbs vibration very well.

The only thing I can think to add to it is a harmonic balance, perhaps on the drum shaft, maybe both ends . it`s basically a heavy round weight, it may cancel out any unbalance of the wooden drum . Of coarse it would have to be keyed to the shaft.The motor would start up a bit slower but once it gets to spinning, the added torque would make for one mean sanding machine.

Great Job Bob!

-- WWW.MACHINISTCHEST.COM

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