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Burs grabbing

I have been trying to make some seats in some round prong settings
and have been having a problem with the stone setting bur grabbing
the prongs and not moving. I was using my Fordom flexshaft and was
working very gently, and very slowly. However, the bur would grab,
and not move. The stone setting bur was the correct size for the
stone I was trying to set. I used Bur-life to facilitate the process,
but it did not help.

I then removed the bur from the flexshaft and put it in my pin vise
and very gently tried to rotate it, but it grabbed the prongs and
would not turn I then switched to the next smaller size bur and had
the same problem, and furthermore when I did get it to rotate, it was
cutting the seat lower than I really wanted, and really chewed up the
bur. It seems to me that the teeth of the bur are too coarse, and
that a bur with finer teeth would work better. When I checked the Rio
catalog, there is no mention of the size of the teeth of the burs,
Does this mean that they all come just one size?

I finally was able to get the seat made, but am not happy with the
way the bur chewed the prongs when I finally got it to rotate. After
using a tiny file, I was able to get them smooth, but wonder if there
are better burs than the ones I have. I purchased them some time ago,
and don’t know the name of the brand. I will appreciate any
suggestions you have as to the best stone setting burs to use, and
any other suggestions. I don’t mind paying premium prices for the
burs. I just want ones that will work without grabbing. Thank you.


Your burs are just very sharp, that’s why they are grabbing. I have
always used bees wax for my burs instead of bur life. Try that and
see if that helps.


I like the high-speed burs Stuller sells. You run 'em at high speeds
and they don’t dull from heat as quickly as cheaper burs.


Try making it go faster to cut the seat to start with. Don’t start
the rotation when you are on or in the prongs. Start outside and get
a medium speed and slowly enter the prongs. If you find it grabbing
your rotation is too slow. Another thing is try high speed burs
instead of the ones you are using. They have a different cutting edge
made at different angles.

Best of luck…don’t be chicken!!!
Russ Hyder The Jewelry CAD Institute

Dear Alma,

Many times the high speed burs have a coarser cut. These burs are
made to last a longer time than the less expensive burs. They do grip
though and travel around the prong leaving nasty marks.

Look for a Busch brand bur. They are a German bur and have less of a
cut. They don’t last as long as the high speed bur, but may be what
you need.

Best regards,
Todd Hawkinson

Thanks Russ for the suggestion. I tried that, but unfortunately I
guess I was not squarely centered over the prongs and the bur chewed
into them, and distorted them. Will keep practicing following all the
wonderful suggestions people have been giving me.


Alma, were you by any chance trying to cut all the prongs at one
time? If so, don’t. Use a smaller bur and cut just one at a time.


I use a air drill to do my stone seats with on difficult settings…
it is much better then most burs as most colored stones are not cut
to match the burs shapes…You might also think about using a higher
speed with the burs you are using. This will not allow it to grab as
easily. … just remember one thing… the price you pay for a tool
reflects the quality… Only buy good quality burs and tools and you
will have better success.

Vernon Wilson

I want to thank everyone for all the wonderful suggestions sent to
me both on and off line about dealing with grabbing burs. I shall try
all of the suggestions, and see which works best for me. You have all
taught me a lot and I am grateful. Thanks to all of you for taking
the time to help me.


Conversing with Alma offline, I questioned which Foredom she has, it
is an old model cc, and that is the problem.

For using burs, you need full torque at all speeds or else you have
no control. Being mostly self taught I massacred many prong setting
no matter how hard I tried, the bur sticks and then goes real fast,
jumps out of the setting and makes bur cuts on the prongs where I did
not want them.

I also suggested pre-cut settings from Tripp’s. I use the sterling
one= s and they work quite well, and I save time and time is money.
They have light and heavy ones. If I make a mold of a piece for
production, I use the heavy setting and it is plenty thick for secure
setting, and unskilled employees can set them!!!

Richard Hart G.G.
Denver, Co.

Try making it go faster to cut the seat to start with. 

Put your foot on the floor… It’s like a circular saw (SkilSaw
or table saw) Put a piece of wood on it and turn the blade by hand. A
tooth of the blade will hit the wood and stop cold. Turn on the
motor to 3450 urpums and it will cut like butter. Those teeth need
to ~move~. There is such a thing as TOO fast, but I’m not sure I’ve
ever found that place.:slight_smile:

No, not everything goes at top speed, but most burs do quite well
there. Use your hand for control and let those burs fly. And Alma’s
particular case could be coarse-cut burs, too.