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Setting Burr Sizes


#1

Hello and happy to report success with my first tube setting
experience after getting good Orchidian help a couple weeks ago
finding the right tubing for the job. Metalliferous to the rescue!

Now onto another related question regarding setting burrs. The above
mentioned tube setting required using a 4mm setting burr which I got
with no problem. Decided to get a couple more (and yes, probably
should just break down and get a good set) and discovered that while
you can order an 4mm setting burr, any diameter smaller than that
decreases by 0.2mm odd increments on down the line (to 1?). In other
words, to tube set a 3mm stone which should require using a 3mm
setting burr…Can’t seem to order that one. Is there a reason why
individual burrs are sold like that? Not sure which one I could use
for a 3mm stone. I’m stumped. This is where buying a set comes in
isn’t it?

Thanks as always for any helpful advice, Carol


#2

I am sure someone will come out with the exact reason for the sizes,
but it seems that the burs are made to the more common stone cutting
sizes. In a lot of our rings I use diamonds that are cut to 1.6mm and
1.8mm. That means I have to use a 1.5mm burr and carefully "enlarge"
the hole. Basically I cut the seat to depth, then rotate the bur in a
circular motion to make the hole bigger, does this make sense?
Another thing that will help, start the hole with a bud bur, which
will be slightly larger than the finished size, giving the opening a
little taper, cut the bottom seat, then rotate the bur. Remember
though, better to cut a little, then have to cut a little more, than
to cut away to much, so gently open the hole.

Hope this helps.

Thank You,
Eric McCafferty
Studio311.com


#3

I took a setting class at new approach school and blaine used nitric
acid to slightly reduce the size of burs just for the scenario of
uncommon stone sizes… he also said it was helpful to resharpen worn
burs by etching them with nitric acid. I have also heard of people
using muratic (the stuff that eats mortar off of bricks) for the same
purpose. has anyone heard the same thing or tried it.

guy g.


#4
I took a setting class at new approach school and blaine used
nitric acid to slightly reduce the size of burs just for the
scenario of uncommon stone sizes.. he also said it was helpful to
resharpen worn burs by etching them with nitric acid 

My understanding is that you want the acid weak so it attacks the
sides of the tooth thus sharpening it. If the acid is too strong it
will round and blunt the top of the tooth first. I’ve heard of using
sparex for this as well as dilute nitric acid.

best
Charles