I have a Taig cnc mill and want to machine some small items for
jewelry. Mostly i will work in wax, but somtimes I want to mill SS
directly. What i ahve so far is the machinist vise that came with it
(too large and hard to get a grip on small items). I am having
trouble figuring out how to hold down small pieces of stock for
milling. The best i could come up with was some bolts/washers screwed
into the table, with the washers holding the stock down. I have seen
hold-down kits and such but they are all for much larger stock.
What about a fixture plate like (via google search on “taig
fixture”): http://www.whitewolfairsmithing.com/taig.htm The other nice
thing about fixture plates is that they protect your table from your
mill. You mill “hello world” into your table once…
Sherline mills are small too, you might want to search for these as
well (check that the sherline and the taig use the same table slots):
Part # Desc.
P/N 3012 Hold Down Set
P/N 3560 Tooling Plate
http://www.cartertools.com/ (he has a link to clamping kits by
Robitek and Spillage International, but those sites aren’t selling
right now. He’s also got a bit on making your own nuts from aluminum
stock)
I have a Taig cnc mill and want to machine some small items for
jewelry. Mostly i will work in wax, but somtimes I want to mill SS
directly. What i ahve so far is the machinist vise that came with
it (too large and hard to get a grip on small items). I am having
trouble figuring out how to hold down small pieces of stock for
milling. The best i could come up with was some bolts/washers
screwed into the table, with the washers holding the stock down. I
have seen hold-down kits and such but they are all for much larger
stock. Any helpful ideas??
Work fixturing is an art all by itself. In the machining industry
there are companies that specialize in supply bits and pieces as well
as full solutions for work holding. Studying what they offer can give
you some new ideas and approaches. One that has an extensive line of
items is www.carrlane.com They are definitely not oriented to the
tiny things in jewelry, but the concepts and approaches are very
good.
One solution that can be quite helpful is to put a tooling plate on
your mill. We sell a couple of different sized ones specifically for
the Taig mill as well as another series for the Sherline mill. They
are listed on our A2ZCNC.com website and can be ordered there as
well. What they are is 1/2" thick precision ground cast aluminum
tooling plate material that we machine to precise size and put in
mounting holes to attach it to your table as well as a pattern of
10-32 threaded holes that allow you to bolt things down directly. You
basically use it as a fixture that you can modify as needed. Many
people will drill and tap additional holes where they need them to
hold special items. Others will set up a number of different
“stations” on the plate that hold things different ways.
For flat work item it is common to use double sided carpet tape to
stick it to a fixture. Another approach is to drill holes through
areas that are on the edges and screw the piece to a tooling/fixture
plate. One very interesting approach for total strange shapes is to
use a low temperature melting (165 - 190 deg F is normal) fixturing
metal. This is an allow that melts in boiling water and like water
expands when it transitions to a solid state. It is listed in the
Grobet catalog as Fusible metal item# 54.812. One ingot is not very
much and getting a few is handy. What you do with it is cut a pocket
into a plate. It ideally has some undercut to it. You then melt the
alloy in the pocket and while that is molten you place your item to
fixture into the molten alloy and keep applying heat until the piece
comes up to temperature and the liquid alloy flows over it. Then hold
it in the position you want and let the alloy solidify. As it cools
to room temperature the alloy continues to expand and locks you item
in place. Machine away. When finished heat the plate and let the
alloy melt. Pull your part out and you are ready to go. The alloy is
completely reusable as long as you don’t ruin it by over heating.
This will not work on wax, but because the temperature is so low it
works with most metals without the fixturing alloy getting into the
work piece alloy.
Tim
A2Z CNC
1530 W Tufts Ave Unit B
Englewood CO 80110
A machinist once told me that you can machine anything if you can
hold on to it… Wise words. So much so, in fact, that there is a
whole category called “workholding”. If you go to MSC.com, enco.com, travers.com - even ebay, there is a whole section devoted to it. A
few tips, though: you can get a toolmakers vise in any size. I have
one that’s 2 inches long by an inch wide. Get some parallels to block
parts up in the vise jaws. Clamp kits come in sizes, it’s true. You
can get individual clamps and all manner of parts in any size,
though. There are also various products, one prominent one being made
by Mitee-Bite, that hold flat work around the edges, without going
over the top edge. I made my own version for a LOT cheaper - they’re
real handy. The real point of this is there is no answer to your
question. You need the tools - vises, clamps, etc. and then you need
to figure out the best way for your particular job every time,
because they’re all different. Angle blocks, sine vises, rotary
tables and such are handy, too. I’d say 1/3 of my tooling (I have a
bench mill R8 spindle, 2HP, 9 x 42 table) is related to workholding.
i made some tiny hold downs for my drill press out of flat steel
stock from a home store ( lowes). It was about 1/4" wx 4mm thick, i
bent pieces about 3 inches long into a modified 7 ( i still havent
figured out how to use a drawing board in email!) basically it
threads through the slots on the mills table and i ground the ends
with a bench grinder to fit a wing nut and there it is…or was…as
they rusted after hurricane katrina- but worked quite well, oh i also
put a small bit of rubber tubing under the wing nut to keep it from
slipping…improvisation yes, but it worked/works well as i haven’t
found any small enough hold down clamps either. Dremel,grs, no one i
know of makes small ones…dremel, in fact recomended that one make
exactly what you described for their drill press tables…
There are a whole series of these fusible metal (bismuth) alloys
that have all kinds of handy uses from fixturing to bending thin
walled tubing to short run dies and metal injection molds for wax and
plastic patterns. There are some things to remember about using them
first most of them contain some significant amount of lead and
should be treated with care to keep from poisoning your self. Some
contain also cadmium. Overheating them can easily be done with a
torch and you can get lead and or cadmium vapors in the air and then
you are well on the way to heavy metal poisoning. Wash your hands
after handling them to keep from ingesting them. Use them with care
and you can do things with them that are very difficult to do any
other way
Jim
James Binnion @James_Binnion
James Binnion Metal Arts
Have you tried Jett Sett? Miraculous stuff. Depending on how small
your stock really is, will determine the workability of the Jett Sett
as a solution for you.
It’s a thermoplastic material that can be used to hold pieces while
setting stones; it can be shaped around tool handles for a better
ergonomic fit. It is softened with hot water and hardens to rock-hard
when cooled.
I sing praises for it! The most complicated job of setting 9 stones
in an articulated piece was made nearly EASY! Just make sure that
when the Jett Sett is soft, you leave yourself the working area to
set stones or do the other work.
Rio Grande sells it. Disclaimer. I’m just a very grateful customer,
happy to be living in the space age.
The Yahoo newsgroup TaigTools is an excellent resource for the Taig
mill and lathe. There is lots of on hold down clamps if
you do a search of the archives.
I think Jet Set could be something like Polymorph, Friendly Plastic,
Protoplast, Shapelock, all of which seem to be tradenames for
polycaprolactone and the like:
I think you can even do lost wax casting with it, although I haven’t
tried that yet.
I’ve never bought anything from Rio Grande. Maybe if they were to
put their catalogs up online in pdf format, I would. It is not that
hard to chop a 1000 page catalog into downloadable 100 page pdf
chunks, I suspect.
I’m up here in Canada. I was wondering, is Indian Jewelers Supply
any good? their prices seem better than Lacy Lools.
For general machining supplies in Canada, all the machinists I’ve
talked to use and recommended Travers Tool Co. travers.com They are
based in the US, and sell quite a bit there as well.
-Sebastien Bailard
developer, reprap.org - self-reproducing 3D printer project
Indian Jewelers Supply is great. It beats the big guys in personal
service, at least in the real- life setting.
But you can just call Rio Grande and set up a customer number (as I
remember) and they’ll send you the hard catalogues.
About the Jett Sett. Sort of doubt the lost wax casting into it
because it is temperature sensitive. Molten wax will probably even
morph it. You can use as a die when hard.
Thanks for the recommendation for Indian Jewelers Supply. I knew to
avoid Finding King, but that was about it.
With Rio, I may try go and get a hard catalogue as you’re suggesting.
It’s hard to say. Teri at Silver & Cameo Heritage Jewelry mentioned
they’ve got a vacuum casting system "new for $500 item number 705-013
". I think I may be a little while figuring this out. Roger Bowersox
let me know about this mailing list, with good on
home-built casting equipment
Regarding thermoplastic, I’m looking to do lost-plastic-casting,
where the model is made from plastic and invested in the usual
manner. It’s a complicated pipe dream right now. If anything comes of
it, I’ll let the list know.
Had a classmate who made a mold straight from the jet sett piece and
then cast a bunch of wax implressions made from the mold into silver.
Left some great detail in the peide and they cast nicely.
1319 W. Alabama
Houston, Texas 77006
voice 713 610 1162
I'm up here in Canada. I was wondering, is Indian Jewelers Supply
any good? their prices seem better than Lacy Lools.
I’ve had pretty good luck with them, but they are a day or two
slower than Rio. I can’t really say anything about their prices,
though. They do carry things that Rio and others don’t, particularly
several unusual forms of very heavy guage sterling wire.
I have ordered some of the Jett Sett and look forward to seeing if
that works. Regarding the low-melting point alloys, I am loking into
them as well. I know of some ‘non-toxic’ alloys using gallium and
bismuth
a2zcnc, in denver, Tim Goldstein, www.a2zcnc.com makes a great hold
down plate of their own design, $80 or so. they really know their
stuff., millign and CNC as applied to jewelry.
the plate just paid for itself in 2 hours on the first piece I used
it on.
the usual disclaimer, no relation, just a satisifed customer
Personally, I do not think I’d trust the Jett-Set or any of the
other brands of these thermoplastics to hold well enough to machine
metal… Most shrink to some degree, and since they are not metal to
begin with - tend to “move” a bit. You have to “wrap” the material
over the edges to keep things from coming out. If you are trying to
be very precise, I’d stick with metal fixtures and jigs.
While most waxes are too heat sensitive to mount into these
plastics, I believe I have a wax I bought from Lacy’s (spelling?)
that will stand the temperature of vulcanizing… Perhaps it might
work if you are dead set on using thermoplastic for fixturing wax?
Brian P. Marshall
Stockton Jewelry Arts School
Stockton, CA USA
209-477-0550 www.jewelryartschool.com
a2zcnc, in denver, Tim Goldstein, www.a2zcnc.com makes a great
hold down plate of their own design, $80 or so. they really know
their stuff., millign and CNC as applied to jewelry
I am no relation of Tim Goldstein either but I have rented bench
space from his workshop in littleton and he really knows his way
around with the CNC…