.062 slots in 17-4 SS

[Lead Screw]

OK-Heres one from work. One of my working buddies has been racking himself for about a week trying to cut .062 slots in some 17-4. He keeps breaking the cutters. Ouch and expensive. He is running a big Lagoon horizontal mill. Water soluble coolant, really flooding good. He has had best luck with TIN coated HSS slitters 3"od with 33 teeth. He has rpm set at 90. He has played with speeds 71 to 112 range. His feed is 3/8---Thats as slow as she goes. The slots are .270 deep and 14 inches long. The 1" arbor has some run out. I think this may be the problem. The cutting teeth get dull then the cutter breaks. They are considering a carbide cutter with inserts. This should help but it is costly. They got about two hundred grooves left.Has anyone ever had any luck straightening a bent arbor.Ithas .010 runout. I ran a file across it and it felt hard. Other than the bent arbor, everything looks good and rigid in his setup to me. Any advice will be appreciated. Thanks

[Thrud]

You certainly should not run a carbide cutter on a bent arbor - get a new one. Carbide can't handle slop like that. Try a screw slotting cutter at higher sfpm - lots of suds. I would do that before going to the Carbide insert slitting saw.

Dave


[This message has been edited by Thrud (edited 11-08-2001).]

[C. Tate]

Sounds like chip clearance problems. The chips may be building up between the teeth or you may be recutting chips. Try using mist coolant blown across the teeth and ahead of the cut to keep things clean.

Surface footage sounds good to me you may want to go to a cutter with fewer teeth to allow for greater chip clearance and higher chip loads. Increasing the RPM will also decrease the chip load and may help. If you are not climb cutting you may want to try.

Would like to know your solution
Good Luck
Chris

[crypto]

Try this stunt. Apply some Sta-Lube (or any other brand) Anti-Seixe compound to the cutter teeth and then just sink the cutter into the cut. Full depth, if you have the guts. I hit on it by accident and could not believe the results. The anti-seize paste is apparently too slick to permit the chips to lodge in the teeth and this permits centrifugal force to throw them out. I've sunk 3" dia. slitting saws full depth into soft aluminum and copper and never had any trouble. Still scares me everytime I use this trick. Cut a 0.006" saw slit 1/4" deep in aluminum, one pass, full depth. Climb milling or conventional does not seem to make any difference.

[toff]

Thanks CRYPTO,
never heard of that one! will try it
thanx
toff

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To know by reading is different than knowing by doing. OR:
What you have going into a situation is knowlege..What you have coming out of that situation (providing you survive!) is wisdom.

[crypto]

Doggone, just wiped out my reply, I'll try again. Here's a bit more info. The anti-seize comes in various formulations: copper, nickel, aluminum. I have used the copper and the aluminum, both work equally well. Auto parts supply houses stock it. The 4oz can comes with a brush in the cap and that is what I use to apply. Just a small application on a few teeth is all that's needed, cutter will quickly smear it on all the teeth. No other lubricant is needed. A long cut such as your friend's will probably require several applications. Have only used this method on soft material but should work equally well. After 50+ years at this game I find it truly miraculous to see a cutter sink so deep into gummy material and then just breeze thru it.
I would'nt be concerned about out-of-round arbor. Hell, most cutters never run very true on their arbors anyway.

[JIM DEWOLF]

The anti-seizing compund is a great idea. I was going to suggest heavy oil but that is better. With an arbour run out of .010" you will have problems. I would try to correct some of that with a hydraulic jack on the table with the draw bar up tight and a dial at top of bar. And of course with the outboard arm in place. With care (don't push too far), you should get it running within .003 to.005". I have had good luck that way.
Let us know how you make out.

[crypto]

Using the mill itself to straighten the arbor is a good idea. May I add to that suggestion that you use a block on the table surface to press against the bend in the arbor. This will permit you to control the bending force with extreme accuracy by noting the readings on the elevation dial as you gradually increase the bending pressure.

[JIM DEWOLF]

That's right Cripto! I often move too fast. Makes me a lousy teacher. Extreem care must be used when using a jack, not to go too far. I would start off with say .025 to .030" just to see if there is any reaction.Move up in .010 incerments till you see a change. You have to be very careful or you can ruin the arbour getting a dogs leg bend, then there is no hope! Just go slow and take lots of time. It can be done. Whach that dial reading on top of the arbour. Good Luck!