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Foam on lapidary wheels


Hi there, I am trying to resurrect some old lapidary equipment. I
have three wheels which have a spongey layer on the wheel to give a
softer base under the sanding belt. The foam is hardened and
crumbly. If I scrape it off and clean off the wheel, what type of
foam should I use and what type of adhesive would work best to hold
it to the metal wheel?? Thanks, Rose Alene (in wet, wet Idaho)


Go to the site: and read the
descriptions of the various materials and supplies. This takes some
time as there is a lot to learn. You can also do the same with Rio,
but Kingsley North sells to the lapidary market, have amore complete
line, and I have found them great to work with. Look also at
Covington Engineering and Graves. Rob


Hi Rose, I did a quick look, and it looks as if Rob was the only
response to your query. If these are the older type wheels that use
sanding/grinding strips that are held on with clamps or nuts through
a slot in the outer diameter of the wheel, then Covington Engineering
(which was one of the companies that Rob mentioned) is probably your
best bet. I have re-habed many of these wheels. Covington sells foam
rubber strips that are made for that purpose for about 4 or 5 bucks
a strip. You will want to scrape the wheels thoroughly (carefully)
down to aluminum. Clean any residue off with denatured alcohol.
Unroll and thumbtack the foam strip to a piece of cardboard. Using a
spray can of contact cement (must say appropriate for foam rubber on
the label, otherwise it will melt your foam), put a light coat on the
foam and set aside for a few minutes to get tacky. Do the same with
the outside rim of the aluminum. When both are tacky (10 minutes or
so) start with one end of the foam CAREFULLY lining up with the slot
in the wheel and the outside edges, and while pulling gently but
firmly rotate the wheel and press the two tacky surfaces together
till you reach the slot again. There will be a small amount of rubber
excess. Simply cut that off with a razor knife using care and the
slot as a guide. There is a learning curve, and you will get better.
Unless the first one is an absolute disaster, it may not be pretty,
but it will probably be usable. This will go better if you can find a
friend with a steady hand to help roll the wheel while you apply the

I have wasted your time, if on the other hand your wheels are the
newer type that has the abrasive strip glued to the foam such as the
type on most new machines, the Genie, and almost everything else now
days. They are a much harder DIY, but the hubs can be sent to the
Johnson Brothers to be repaired with most of the common grits. Lastly
if these are expanding drums, which are still made, but are of harder
rubber (belts are made to be slipped over the outer diameter of the
wheel), they to my knowledge cannot be repaired. As Rob pointed out
there are many supply houses, all with toll free numbers, and usually
with free catalogs. A couple more are Crystalite, and Indian Jewelry
Supply, and Diamond Pacific. The reason I mentioned Covington, is
they still sell the old “thumper” wheels, and both rolls of SIC
stripping, along with diamond abrasive strips. Good luck, lapidary is
a great creative outlet! Thomas III