Washer die & sanding mandrel

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This article was originally posted as My first scales: Purpleheart with brass inlay by vladsch.

Here is the jig (modified from Bill Ellis' version) and mandrel for sanding.

Making the Jig[edit | edit source]

The jig is made from 1/2" steel rod available from local hardware store. I made one piece about 3" the other 1". This is almost identical to Bill Ellis' jig with the difference that it is all made from 1/2" rod and the post is NOT glued in. This allows it to be removed with the newly made washer and then tapped out of the washer.

  1. Drill a 1/16" hole to a depth of about 1/4" to 3/8". Make sure the hole is vertical. Centering is not as critical. In one of the pieces drill out the washer shape using a 3/16" drill. Do it a little at a time so you don't make it too deep. (Pictures 1, 2 and 3)
  2. Cut off the bottom of a 1/16" drill bit to use as a post. The two pieces should fit flush with the post in the holes. If not then shorten until they fit flush. (Picture 1)
  3. I sanded down the faces by putting one of the rods in the drill press and skewering a folded a piece of sandpaper (so you get sanding action on both sides) on the post then sandwiching it with the other rod at the highest drill press speed. After a while the two faces were sanded smooth and flush. This was not really necessary since you will sand the washer anyway.
  4. I place the longer piece in a small vise as in picture 4.
  5. Insert the 1/16" post into a brass or copper 1/16" I.D. tube (pic 5) and cut about 1/10" by pressing a knife (I use a carpet knife) with a rolling action. After a few seconds the tube will be scored all the way through (pic 6). Pull out the post with the cut off tube (pic 7).
  6. Place post into the rod (pic 8) and sandwich with the second. After a few taps with the hammer the rough washer is formed. (pic 9).
  7. Take out the post with the washer and remove the washer. I place the two into pliers and tap out the rod with a hammer as in pic 10.

Further Experimentation[edit | edit source]

In Bill's original jig the post is glued into the rod this creates more handling and difficulties in removing the finished washer. Finishing the washer requires sanding and polishing. I experimented with a few methods and finally lucked into this one.

  1. Make a conical mandrell to fit the washer. My experimental version was ground from a small screw by placing it in a dremel and grinding it against a rough stone.
  2. Place a newly minted washer on the conical post, seat firmly and grind off any of the post that sticks out. (pics 11, 12, 13 and 14).

Sanding & Polishing[edit | edit source]

Here are heat treated samples on top of an untreated one. BTW I got the wood from Lee Valley. 3" x 24" x 1/8" for about $10 Canadian. They have a few exotic woods from 1/8" to 3/4" thick.
  1. Place the conical mandrel into a dremel (pic 14).
  2. Place a newly minted washer on the conical mandrell, a bit of pressure will firmly seat it (pic 15). Make sure it is well aligned otherwise it will sand lopsided.
  3. At the lowest speed sand with 320, 600 and 1500 grit. I do it by pressing the sandpaper with my finger against the washer.
  4. Dip the sanded washer lightly into polishing paste (any brass/copper polish will do) and press into a kleenex or paper towel to polish. Mirror finished washer in pic 16.
  5. Newly minted washer back side is rough (pic 17). Sand it smooth by running it on sandpaper with your finger a few times (pic 18).

Cutting, stamping and sanding/polishing takes a bit under 4 minutes without rushing.

I also heat treated the wood to give it a deeper color. I accidentally discovered that purpleheart turns a deep purple when heated during sanding. So I experimented and figured out that if you bake it at about 275 F for 90-120 minutes it becomes a deep purple. Increase the temp to 300 F and you get a very deep purple but leave it too long and you get almost black.