cutting flutes/miniature work - help!

[M.Baunach]

Could use any help or advice on methods of cutting flutes(straight) in stainless and titanium on rods 2.5mm in dia. Finish is critical and process must be repeatable. Length of cut is only 3mm so I shouldn't need any type of follower. The tricky part:I only have a Bridgeport type verticle mill and a 9" Southbend lathe at my disposal. Also, no need for indexing since flutes will oppose each other(180 out). Depth of cut approx. 1mm.

Miniature endmill, burrs, grind - ?

thanks
Mike B.

[SGW]

I take it these flutes are lengthwise of the rods. I'm not sure what you mean by not needing indexing, if the flutes need to be 180 degrees apart; you need to determine that, somehow.

How long are these rods? How wide are the flutes?

I'd be inclined to use a slitting saw, I think, if you can live with the saw runout at the end of the flutes. Or do you not want square edges/bottom?

[Thrud]

Mike

I would support the work with a v-block to prevent deflection. An indexer on one end will insure true 180* placement of the slots.
As SGW states, the physical property requirements of the slot will determine if you can use a saw or an endmill to cut the slot.

You say repeatability is paramount - to insure this you will have to use an indexer. A 5C Spin Index (Bison makes a really nice one for under $120) would work fine and an internal stop in the collet could position the rods the same way every time. If the rods are realtivly short the indexer alone could support the rod close to the machining.

A sharp carbide endmill at maximum mill speed using coolant or cutting fluid to assist cutting action should make short work of it.

Dave

[kap pullen]

Had a job once cutting keyways for a compressor company. Thousands of shafts.
Started with end mills but had constant wear, and breakage problems.
We finished up with woodruff kew cutters (and side cutters).
This eliminater all size, and wear problems to a managable level.
Don't know what kind of flute you are cutting.
Kapullen

[halfnut]

M

You never mentioned the lenth of the rods, nor the exact profile.

I see clearance problems with a standard indexing device. Building a special indexer might be the answer, something small in diameter to allow one to cut that flute with the least amount of overhang. A collet type end such as used on a pin vice comes to mind, not that hard to make. This on the end of, or made directly onto a lenth of drill rod, fitted nicely into a block which is split with a cramping bolt. On oposite end a simple pin or notch indexer.

2.5mm with 2 cuts opposite, 1mm deep, that only leaves .5mm in middle, or just a bit over 1/64th for us English thinkers.

Tiny!

[crypto]

You must be joking.

[Thrud]

Crypto

I never doubt much anymore. Just when I think I have seen it all , I am proven wrong by some so-called engineer - it disgusts me that they have the nerve to call themselves "professionals". (I am not putting down good engineers, just the twits) Common sense is apparently never a factor with some people.

[crypto]

Until Baunach discloses 1.the exact grade of titanium or stainless to be used 2.flute profile 3. surface roughness grade required 4. quantity. I say it's a joke.

We all know there are vast differences between stainless grades not to mention the differences between grades of titanium. First question I always ask of any customer is --WHAT IS THE MATERIAL?

Engineers! there's some good ones and there's the others like; the one who said there was no steel in stainless, the one who had never heard of a broach and on and on.

[M.Baunach]

The problem we are having is one of clearance. The length of rod to be fluted is 3mm and this sits at the end of a 6mm dia. rod that is 50mm in length (visualize an unsharpened pencil with its graphite core extending 3mm out of the end).

Tool clearance is a problem using coventional endmills, burrs, slitting saws etc... The exact grade of Ti or alloy of stainless steel is of no consequence here - methodology is what I am addressing.

Surface roughness is a concern, although one would assume that generally a smooth surface will carry away material more efficiently than one which is rough. As far as flute profile, I stated straight flutes but this may seem ambiguious to some because I didn't mention wheather they be cammed, receeding, involute etc...something we still have not determined.

For those individuals who have replied that this is "stupid", please try to remember that I was only wanting responses related to empirical methodology, I did not intend for anyone to split hairs and reinvent technologies. If you don't have any knowledge to contribute, simply don't.

Many others are providing solutions and great advice(we are rapid prototyping several designs right now).

My thanks to those who replied with insightful suggestions.

[JCHannum]

Back to the old "There are no stupid questions thing."

Almost sounds like job for EDM. But thaat is not available.

How about high speed dental burr. There was article in HSM or other a couple months ago mounting Dremel tool in milling machine. This may be a little crude, but a high speed precision grinding spindle may not be out of the question. Possibly use in lathe rather than mill.

I am constantly amazed by watch and clock making tooling. Very simple and accurate. Been around for years, and we try to reinvent wheel.

------------------
Jim H.

[snorman]

Good idea JC. If they can index close enough in the lathe, just stick a carbide burr in that Dremel, strap it to the tool post(somehow?), and make itty bitty chips.

There's a site somewhere on the net that shows how one person attached a hobby grinder to the tool post. Anyone have that handy?

I am constantly amazed at how carbide burrs can stand up to grinder speeds and keep on cutting. We use them in air grinders for rough stock removal and they flat out get with it.

Steve

[This message has been edited by snorman (edited 01-15-2002).]

[Oso]

That would be the 'varmint al" website. don't remember the URL.

[Rich Carlstedt]

There is hardly any room to properly grind or mill the flutes as described.
An alternative method is to make the 3mm flute diameter as a rod or EDM small pieces and then under-bore out the 6mm rod , heat it , and shrink it on the flute section

Only grinding will solve your surface finish spec, or Electromachining !

My 2 cents

[Thrud]

Mike B.;
From your updated discription, I do not see any reason it could not be mounted in a 5C spin indexer. An internal stop could be used to insure proper positioning of the rod. The end to be milled could be just hanging out a bit and it could be milled easily in the vertical mill.

If you use a smaller burr or endmill the highest rpm you can muster will be required.
If a number of these are being made an air grinding attachment that can spin up to 60-100K rpm may be worth looking into (NSK Planet). Equiped with a diamond wheel you could even hog out Carbide rods if you wanted too.

Spindle speeders are available in R-8 that can up RPMS to 20K.

I hope this helps.

Dave

[SGW]

Somebody a few notes back mentioned a Dremel tool. Maybe the bearings in my Dremel are just trashed, but the times I have tried using it to grind in the lathe have produced surface finishes that aren't all that great. But a weeny carbide burr, using a quality grinding spindle (maybe just a NEW Dremel tool, although I think you'll need something better) ought to do it. I like Thrud's idea of the air grinding attachment for the Bridgeport.


[This message has been edited by SGW (edited 01-16-2002).]