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Picture of Sanding Drum for a Thickness Sander
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I decided that I wanted to build a Thickness Sander so that I can sand boards that have been glued together for segmented wood turnings. When you have multiple species of wood at different angles, you can't run them through a planner anymore.

I found a set of plans at http://www.shigshop.com/thickness-sander.html for a thickness sander, bought them, and embarked on the task of building this project.

It is a lot of fun -- and a reasonable amount of work. Since I am making this at Tech Shop, I have all of the space and tools necessary to make the job easy.

So far, I have the sanding drum and four conveyor supports done. It has taken me about 20 hours to get this far.

 
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Step 1: Cut out the MDF disks

Picture of Cut out the MDF disks
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The plans call for 38 5 1/2" MDF disks and 128 2 1/2" MDF disks.   

I made these on a CNC shopbot using vCarve Pro.  The MDF is 3/4" thick.

Click here to see the ShoBot do it's stuff:  http://youtu.be/Febtki81qE0

Step 2: Prepare blocks for use as rams for the glue-up process

Picture of Prepare blocks for use as rams for the glue-up process
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I purchased 1" cold rolled steel rods and cut them to length using a metal lathe at Tech Shop.

I then cut 2" square blocks of pine and drilled 1 1/8 holes in them.  I built a jig to allow me to quickly and safely drill the large holes.  I used a forstner bit,

When I was done, I had about 35 blocks.

Step 3: Glue the MDF Disks to 1" Steel Shafts

Picture of Glue the MDF Disks to 1
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The steel shafts are 1" in diameter and the ID of the disks is also 1".  This makes for a tight fit.

I drilled a hole in a 4x4 and placed the shaft in the hole.  I then placed the disks over the rod and used a 10 Ton arbor press to force the MDF disks down the shaft. 

I used Original Titebond PVA glue and liberally applied glue to the disks.  I then used the wooden squares and the arbor press to ram the disks together on the steel shaft.

This took a while , but I was able to apply pressure.  Note the glue squeeze-out.

I used long clamps to apply pressure while the glue dried.

Step 4: Use a router and a fixture to turn the MDF disks round

Build this fixture and mount two bearings on it using bolts.  Mount a shaft with the MDF disks in the fixture.

Use a 3/4" flat router bit and go back and forth with the router slowly turning the shaft.

This takes about 45 minutes to an hour for each shaft.  You need to take your time and use feeler gauges to adjust the height of the router as you measure the diameter of the disks / shafts.

This video shows the process.  http://youtu.be/lnMJCr7mGp4

Step 5: Measure and prepare for sealing with Polyurethane

Picture of Measure and prepare for sealing with Polyurethane
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Use a caliper to measure the diameter of the drums.  I wanted the diameter to be 5 inches.  I was a little bit off -- 0.002 is not that bad.

Note the dust from routing one of the drums round.

I sealed the drums with three coats of poly in the Tech Shop finishing room

This was a lot of work -- but it should pay off in the end.

As it stands right now -- I have twenty hours of work.  I have the drums for a thickness sander completed.

I made it at Tech Shop!
lafnbear1 year ago
Forgive my ignorance... you're making this sander to thickness sand wood for turning; why didn't you just turn the rollers from a hardwood instead of gluing them up from mdf disks?
CWKr (author)  lafnbear1 year ago
“When I was a boy of 14, my father was so ignorant I could hardly stand to have the old man around. But when I got to be 21, I was astonished at how much the old man had learned in seven years.” ― Mark Twain

Lafnbear -- Good Question -- I was going to go that route until I realized that the drum and rollers are affixed to a 1" and 3/4" shaft respectively.  The drum needs to turn at 1725 RPM.  There is no way to glue the shaft to a 38" hole that would have had to have been bored through solid wood.

The MDF ( it could have been plywood too) is glued at every point along the set of MDF disks.  There is also a great deal of friction holding each disk on to the shafts.  It was very difficult to press a 3/4" thick disk onto a shaft when I was ramming more than 2.  More than five was a "tactical error" -- I actually had to cut some of them off and start again.

I can't imagine how many tons of pressure I would have needed to get a tight fit if I had turned a 38"+ length of wood. bored a hole, then added glue and tried to push a 1" steel rod through it.