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BETTER Field Solution Needed: Back spotfacing Inconel

Ready4Launch

Plastic
Joined
Feb 11, 2019
Hi - sorry, first post and quick intro... Working in powergen field, ME background, Field Engineer, and now working in contract management ... not pretending to be a machinist although I understand some of the techniques and such.

Here's the situation. I am on the freakin' Hawaiian island of Oahu. I have a fairly large casing with 22 holes. I need to have some spot faces cut into the bolt holes for a spacer to sit. Given the setup, we had to flip the casing to be able to get a magbase drill over the hole center. We're currently using the magbase with a morse taper and custom made cutter blades (2 blades opposite). We're having to cut into the case, which is Inconel, to a depth of about 3mm. The spotfaces are 43mm in diameter. Since, the drill is mounted on the upside-down flange of the casing, the shank drops through the hole, and the drill is pulling upwards to apply pressure to cutting surface. Of course, with the morse taper, this is not ideal.

I've done quite a bit of researching for back spotfacing tools made out of carbide, but it seems that the ideal fix is a complicated tooling setup designed for automated shop work and not a field application. However, that is why I'm posting here to see if someone more knowledgeable than I knows of a setup that would work.

I'm also trying to see if I could get a portable, hydraulic Lamina mag setup. But, time is money, and I've got a time clock running to finish this work, rebuild, and start the unit before we get into some serious liquidated damages.

Looking for miracles...

#hawaii #inconel #complicated #hotmess #getmeouttahere #theoddsagainst :wall::bawling::drink:
 
#hawaii #inconel #complicated #hotmess #getmeouttahere #theoddsagainst :wall::bawling::drink:
I would like to help you, and have some experience in this area, but
cannot for the life of me understand the above quoted.

I think, above all, it shows your not very serious about this problem/job.
 
You did not mention the drill hole diameter, which is an important factor in rigidity and reducing deflection.

You may need multiple back spotface shanks to suit wildly varying drill hole diameters... .002/.004 inch clearance drill hole to back spotface shank would be ideal.

Have you looked at Eclipse back spotface tools?

I'd think multiple HSS back spotface tools at low speed 45~50 RPM (20SFM) and light feed with lots of oil or coolant on the spotface cutter and the back spotface shank. Tool life with HSS will be poor, but it is a tough material for difficult applications.

Mike
 
Try calling Vermont Indexable tooling. Your going to want something that uses an insert, because you're going to go through a lot of them. If you're in such a bind that you can't afford the time it takes, well, that's just too bad.
 
Depending on how the spacer is supposed to work, you may have to control the depth of cut of the spot face to a high level of accuracy. I might suggest that instead of trying to do that in the field, that you do a simpler process of creating a spot face in whatever method works for you (and a generic mag drill isn't that stiff, and so isn't ideal for for Inconel), then map out the actual spot depths at each position.

Then cut the spacer pads (as that's what it sounds like actually fits in the Cbores) to suit. This can be done in a conventional shop with the right equipment on hand.

For the mag drill, you could try drilling with carbide drills into the Morse socket, then trying to tap with hi-hardness taps for set screws to retain the taper shank. You might look at carbide spade drill inserts in a custom shank to do the actual cutting, they're easy to replace and available in a ton of sizes and geometries.

Heck, fly me out to HI and I can set up the process for you... :D
 
It doesn't sound like the depth is super critical since the spotfaces are on the outside of the casing. I would follow Mike's advice and if you have trouble with the tools popping out, dsergison's. (Try to use the pin over the Loc-Tite). Very important to try to match the spotface tool shank to the hole with minimal clearance. If you have to, make a bushing for the holes. Order a stack of spotfacing tools so that you don't have to dick around when one gets dull.
 
Eclipse makes the same type of back spotfacing tooling as the stuff Sami posted - and I know they have carbide versions too. I would not bother with indexable tooling since with these types of cutters it's so quick and easy to change the entire cutter head. Just get multiple cutter heads and swap them if they get dull. Sharpen them up again after the job's done. If you're up against a big financial penalty deadline don't monkey around with anything else. Buy a couple shanks (insurance) and a bunch of cutter heads off the shelf from either of the posted manufacturers that will work and make a bushing (that is a slip fit in the hole and on the spotfacing tool shank) with a flange to move and drop into each hole as you work on it.
 
Wida Metcut is another name for back spotfacers. The back spotfacer is a tool that slips on the shank after the shank is placed through the hole. The cutting tool is a 1/4 turn set-up that is held in place by the cutting force. The cutter will do the job if your portable drill is up to the task.
 
I would like to help you, and have some experience in this area, but
cannot for the life of me understand the above quoted.

I think, above all, it shows your not very serious about this problem/job.

#youknowexactlywhathemeans #hesamillenial #giveitarest
 








 
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