Flex-shaft tool advice, too!

First, thank you to Peter and everyone who gave their thoughts about
soldering equipment. I think that I will take the advice of having a
"Y" connector and both full size and a little torch handpieces. Still
haven't decided on gas, yet, although I am leaning toward acetylene
and oxygen.

Being new to jewelry making, I need to purchase everything - and there
are so many things, ultimately, needed. I hope to buy the soldering
equipment in the next week or so and will plan a flex-shaft tool for
next month. Everyone seems to recommend the Foredom models. I was
wondering, though, about the Foredom flex-shafts that come off of the
Foredom bench grinder. Would this be a better use of resourses - kind
of like two for one, or should they be separate units?

Other equipment I am planning over time (not including little things
like files, hammers, saws, etc) would be a shearer and a rolling mill.

Please tell me what you think are the most important tools to have and
what your favorite brands are. What equipment couldn't you live
without?

Thanks all for being so generous with your knowledge.

Best,

Raane

I think that I will take the advice of having a
"Y" connector and both full size and a little
torch handpieces.

Another option is female quick-disconnectors on the hoses coming off
the tanks and male connectors on each of the torches. That way you
can swap torches in seconds without always having to struggle with
tangled hoses etc.

I was wondering, though, about the Foredom flex-
shafts that come off of the Foredom bench
grinder. Would this be a better use of resourses -
kind of like two for one, or should they be
separate units?

Personally I've found that the speed ranges of the flexshaft to be a
pretty significant issue and in the end that's what's guided my
purchases. Cleanliness is another factor.

Grinding/polishing is usually a relatively low speed operation, in the
1500 to 3500 rpm range. Some wheels and mops become a safety risk if
they're run faster than this. Grinding/Polishing is also a pretty
dirty job and it's highly advisable to do it away from your smithing
bench. Weather permitting I take my grinder outside, that's how much
of a mess it can be. Also consider that you can get an acceptable
stand-alone bench grinder for US$50 or less. It ain't fancy --fixed
speed, non-reversible-- but it does the job.

Hammer (and engraver) handpieces also require low speeds, though they
need speed variability unlike the typical grinding/polishing process.
My hammer handpiece for instance is rated at a max of 5000 rpm.
Running it faster could permanently damage it. Drilling is also often
best done all lower speeds. All of this means that having a good,
low-speed, variable-speed motor can be a significant benefit.

On the other hand there are many flexshaft bits that benefit from high
speeds, up to 18,000 rpm or more. Running these at lower speeds will
often result in inferior operation or even damage to the bit.

Reversability can also be a good feature to have. I frequently make
my own small, specialized tools which means I do a lot of detailed
grinding and cutting. Having a reverse on your flexshaft can be a
distinct advantage in cases like this.

So what does all this boil down to? Every person's needs and
preferences are different, of course, but my solution has been to have
a cheap bench grinder for grinding/polishing; a low-speed Series L
Foredom for drilling, special polishing needs and my hammer handpiece;
and a Series SR Foredom for high-speed and reversability. No doubt
we're talking a non-trivial investment in motors here but once you've
purchased a number of handpieces, scads of drills and bits, and
grinding/polishing wheels you'll see that the motor costs are quickly
dwarfed by your investment in accessories.

My process was to use inexpensive Dremel tools for years --I went
through at least 4 of these-- until I upgraded to the (vastly more
appropriate) Foredom SR. Almost all of the Dremel accessories I'd
bought over the years were usable on the SR. I added the bench
grinder soon after and then popped for the Series L when my budget
permitted.

I hope some of this is useful to you.

Cheers,
Trevor F.

On 11-Feb-2004, (TrevorF) wrote:

Grinding/polishing is usually a relatively low speed operation, in the
1500 to 3500 rpm range.


Flag on the play!! This TOTALY depends on the wheel make up and diameter,
check manufacture spec and do not over speed.
I put a cretex(sp) wheel on an air grinder that would spin 50,000 rpm on 90
psi, shop air was over 100 psi.
It left a large knot on my forehead, been there done that.


On the other hand there are many flexshaft bits that benefit from high
speeds, up to 18,000 rpm or more. Running these at lower speeds will
often result in inferior operation or even damage to the bit.

Ah..in a word no. Cutters are never damaged by spinning too slow. If they
are damaged it will be to too high a load, too high rpm, cloging leading to
over heating, etc. But it wont be because they spun too slow.

I'm not knitpicking Trevor,(at least I hope I'm not). I may be a crummy
jeweler, but Iknow how to cut metal

Les

On Wed, 11 Feb 2004 20:31:49 -0800, in rec.crafts.jewelry
wrote:


On 11-Feb-2004, (TrevorF) wrote:

Grinding/polishing is usually a relatively low speed operation, in the
1500 to 3500 rpm range.


Flag on the play!! This TOTALY depends on the wheel make up and diameter,
check manufacture spec and do not over speed.
I put a cretex(sp) wheel on an air grinder that would spin 50,000 rpm on 90
psi, shop air was over 100 psi.
It left a large knot on my forehead, been there done that.



Les, I think you misread Trevors post on that point. he's suggesting low rpms,
not high. At the speeds he suggests, you're not going to be destroying any
abrasives or rubber wheels from too high rpm. Now, I'll agree wholeheartedly
that all wheels have manufacturers specified maximum rpms, which must be paid
attention to for safety. some rubber wheels can run at very high rpm, but most
specify max speeds more in line with what a normal flex shaft can produce.
Many of the smaller, permanently mounted harder rubber silicone wheels, the
type originally produced perhaps more for the dental technicians, are made with
the micromotors in mind, which are more common in those settings than standard
flex shafts. The micromotors often will turn at fairly high rpms compared to a
flex shaft (My flex shaft maxes out, says the nameplate, at around 18,000 prm.
My little micromotor (fordom, one of the cheapest, lowest power, and slowest)
goes 35,000 rpm at full throttle. The little shofu wheels, among others, are
quite happy, and in fact VERY effective at such high rpms, as they then need
only the slightest touch to cut well. On the other hand, one of my favorite
wheels is a soft, semi-coarse grey silicone abrasive wheel from Pacific
Abrasives. I usually use it at only low rpms.

On the other hand there are many flexshaft bits that benefit from high
speeds, up to 18,000 rpm or more. Running these at lower speeds will
often result in inferior operation or even damage to the bit.

Ah..in a word no. Cutters are never damaged by spinning too slow. If they
are damaged it will be to too high a load, too high rpm, cloging leading to
over heating, etc. But it wont be because they spun too slow.


Um. here again, Trevor is sometimes right. Too slow a speed won't overheat a
cutter, to be sure. but Carbide, in particular, is brittle. To fast a cut
will chip the teeth. Running small carbide bits slowly is a great way to wear
them out prematurely. run at high speed, each tooth is taking only a very tiny
cut per pass through the metal, and they last a lot longer. Plus, at high
speeds, burs don't grab and catch the way they can at low speeds. As with the
rubber wheels, it depends a lot on what type of bur or cutter you're talking
about, and what it's made of. The high speed steel ones tolerate high rpms
very well, though some of the larger ones can be more dangerous this way if
they get out of hand somehow. The smaller, dental type, busch burs work well
at high rpms IF, and only if, one takes very light cuts. If you bear down on
it at all, you overheat it and destroy it. But a tiny busch bur at 30,000 rpm,
used gently so as not to overheat it, is often just fine, and more easily
controlled than at lower speeds. As with abrasive wheels, these are generally
marked with a max rpm, and one should pay attention to those specs.

Peter

Not to take too firm a stand here...but I am




Um. here again, Trevor is sometimes right.

We are all sometimes right

Too slow a speed won't
overheat a
cutter, to be sure. but Carbide, in particular, is brittle. To fast a
cut
will chip the teeth.
Sorry wrong, you have mixed up cause and effect here. High rpm will do no
harm, it is the chatter, the vibration that breaks the teeth.



Running small carbide bits slowly is a great way to
wear
them out prematurely.

No..slow rpm will not cause faster wear, too high a chip load will chip
teeth. If you are removing the same abount of material, in the same time
span at a lower rpm chip load has gone up.


run at high speed, each tooth is taking only a very
tiny
cut per pass through the metal, and they last a lot longer. Plus, at high
speeds, burs don't grab and catch the way they can at low speeds. As with
the
rubber wheels, it depends a lot on what type of bur or cutter you're
talking
about, and what it's made of. The high speed steel ones tolerate high
rpms
very well, though some of the larger ones can be more dangerous this way
if
they get out of hand somehow. The smaller, dental type, busch burs work
well
at high rpms IF, and only if, one takes very light cuts. If you bear down
on
it at all, you overheat it and destroy it. But a tiny busch bur at 30,000
rpm,
used gently so as not to overheat it, is often just fine, and more easily
controlled than at lower speeds. As with abrasive wheels, these are
generally
marked with a max rpm, and one should pay attention to those specs.

Peter

FYI carbide can run very hot and not lose strength, like up to 1000 deg F.
There is no danger of over heating carbide, only chiping it. It is
impossible to over heat carbide on jewerly. I dont think anyone has seen
there bit glowing. In a nut shell carbide wont wear out any time soon,
but it is easy to chip, same result only faster!

If you steel bit is blue it got too hot, but I bet you knew that.

If you have chatter when using burs, try a slower speed, or a heaver cut.
Holding tool with both hands can help dampen vibration.
Steel bits are going to be much less prone to chiping from chatter, but are
softer so they wear faster and can be over heated.


And use lubercation(sp) if you can to keep from loading up the bit. Coolant
can be messy to use but it is the cutters friend.

Les

Thanks Peter, you caught the intent of my post where I perhaps wasn't
being quite specific enough. I was offering general advice in
response to what I read as a very general question. From the nature
of Raane's question I thought that that's what would be useful.

Since Raane had mentioned "bench grinder" in the original post I
figured that that's the sort of applications they had in mind. And
that's where I had some hard-knocks experience, in particular, so I
thought it would be worth sharing.

And yes, I was cautioning against running grinding wheels --such as
bench grinder wheels or the cheapo grinding wheels on 1/4" shafts-- at
too high a speed. As indicated there are of course a myriad of
cutting/grinding/polishing wheels that are rated much higher than
typical bench grinder speeds.

Cheers,
Trevor F.

On Thu, 12 Feb 2004 08:13:58 -0800, in rec.crafts.jewelry
wrote:


Too slow a speed won't
overheat a
cutter, to be sure. but Carbide, in particular, is brittle. To fast a
cut
will chip the teeth.
Sorry wrong, you have mixed up cause and effect here. High rpm will do no
harm, it is the chatter, the vibration that breaks the teeth.



Apparently, I wasn't clear. I used the word "fast" to indicate too heavy a
cut, not speed. Sorry. I did not say too high an rpm will damage carbide.
it's the reverse. But note that it's not, as you say, the low rpm that does
it. Carbide can take this just fine. And in a properly ridid machine tool
setup, where workpiece vibration and tool vibration are minimized, the
situation is quite different from a hand held workpiece with a hand held
handpiece. We are, in essence, saying the same thing, but debating the words.
In PRACTICE, no matter how you refer to it, running small carbide cutters at
high speed will let them last longer and not end up with chipped teeth, since
running slowly, vibration, and teeth snagging, and the like, will end up
overloading individual teeth and chipping them. We're agreeing on what breaks
carbide, just wording it differently, and your background with working in
machine tools rather than hand held cutters may be affecting how you read my
post.



Running small carbide bits slowly is a great way to
wear
them out prematurely.

No..slow rpm will not cause faster wear, too high a chip load will chip
teeth. If you are removing the same abount of material, in the same time
span at a lower rpm chip load has gone up.



Which is precisely what I said.


FYI carbide can run very hot and not lose strength, like up to 1000 deg F.
There is no danger of over heating carbide, only chiping it. It is
impossible to over heat carbide on jewerly. I dont think anyone has seen
there bit glowing. In a nut shell carbide wont wear out any time soon,
but it is easy to chip, same result only faster!

High speed steel, too, is pretty resistant to overheating, though not as much
as carbide. By the way, one metal in particular will wear out cutters (and of
them) quickly if you arent' careful. Platinum, though soft, is tough enough
that it creates more drag and friction on a cutter than other jewelry metals.
Steel burrs, even HSS ones, dull a lot more quickly. And my comments about
carbide teeth chipping easily if the bur is run too slowly apply especially to
working in platinum. This is sometimes important, since carbide cutters and
gravers in general, work a lot better in platinum than steel tools do. Steel
tools, even gravers, tend to weld or adhere, (or whatever you want to call it)
to the cutting edges. So then the surface finish of the cut goes down.
Compare the degree of bright cut you can get with even a perfectly polished
steel graver with what you can get with a carbide one, and you'll see the
diference. Plus, the carbide one will cut with a good deal less effort.


And use lubercation(sp) if you can to keep from loading up the bit. Coolant
can be messy to use but it is the cutters friend.


Not all are messy. Rio's burr life, and products like it, are dry, yet work
quite well. And who's paying attention to a little extra stuff around the cut
when using it cuts drill breakage in half?

cheers

Peter