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1/8" end mill extension

madmachinst

Stainless
Joined
Jan 15, 2007
Location
Central FL
OK I am working very near the edge of my 5c spin index. I have already broke at least 3 end mills keeping the cutter fairly extended in the collet. That is Not and Option. What I need is something that will allow me to get some extension. I have been able to use the drill chuck, but I believe that should kill the end mill way prematurely. BTW, the cutter diameter is .110 and LOC is 3/16 I am going 4800 rpm and .0005 IPT feed. YOu guys think something like what I need can be made on a lathe? My other constraint is paying $200 in that one item for a $200 job just doesn't make sense, but I want to get the job done, cause there "might" be more work coming.
Thanks everyone.
John
 
I can't tell how much vertical reach you need , from the bottom of spindle I assume. You might try an endmill holder as it usually extends further from spindle. I would think a drill chuck would have unacceptable runout, depending on brand. This might lead to more brokem EM's. Making an EM holder would be a straight fwd job on lathe, though.
 
PM your e-mail and I'll send you a plan tonight. You have to be good at tapers. I dunno how well it will work for you. You might be able to google the same thing if you don't want to wait.
 
I'd be afraid to make more than 0.010 DOC per pass with a stuck out 1/8" end mill.
 
AB Tools makes precision endmill extensions. In fact, I saw one at Destiny Tools being used for holding endmills while being ground.

These are top shelf, none better that I've seen, call AB Tools and get one.
 
Hardinge also makes extended nose 5C collets, with a reduced diameter at the tip, for clearance away from the indexer. Maybe find a used one?
 
Use a DA-300 Collet holder with a 5/8 shank and grab that with a 5/8 R-8 collet in the mill spindle. Stick it down all you want then!
 
Cheap and cheerful get over;-

Use the largest dia of steel you can, drill, BORE and ream the cutter hole and turn the collet chuck E/M holder dia AT THE SAME SETTING loctitie / set screw the cutter in and you're away.
 
I second the DA collet holder. It was the first thing that came to mind especially with a small end mill like 1/8". But I will add that somewhere I read that these are not supposed to be used for milling purposes but rather just drilling. Has anyone else seen this before?
 
Cheap and cheerful get over;-

Use the largest dia of steel you can, drill, BORE and ream the cutter hole and turn the collet chuck E/M holder dia AT THE SAME SETTING loctitie / set screw the cutter in and you're away.

Cheap, quick, dirty. That's exactly what I was going to say. I'd use drill rod so you don't need to do the collet end. Make it nice and long and you have an extended cutter for future use.
 
I second the DA collet holder. It was the first thing that came to mind especially with a small end mill like 1/8". But I will add that somewhere I read that these are not supposed to be used for milling purposes but rather just drilling. Has anyone else seen this before?

I'm using this one today, 5/32 carbide EM, .317 deep in 7075, full slotting width.
 

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I second the DA collet holder. It was the first thing that came to mind especially with a small end mill like 1/8". But I will add that somewhere I read that these are not supposed to be used for milling purposes but rather just drilling. Has anyone else seen this before?

Mine are all Erikson QC30 (NMTB30) to DA-300 for a cnc mill!
 
come on folks, how about concentricity. I though that it has to be some where like .0002 for end milling. I never saw those plans that Knudsen was offering. anyone have a link, just curious.
 
Done it like Limy Sami said at least a dozen times.
OD and ID in same chucking, concentricity should come out better than your end mill is and way better than any 5C collet. If you are lucky you'll get some runout in the adapter which you can rotate to eliminate the error from the 5C. :)
Bob
 








 
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