# Runout Redemption



## petertha (Apr 23, 2019)

I bought this LFA 0-0.25" range mini chuck a while back & finally got around to 'almost' using it. I put some accurate pins of various diameters & it measures consistently crappy runout. Like north of 0.004" so I am a bit bummed. The mechanism is smooth & jaws close nice. I have a larger LFA in my drill press & is pretty decent at least for that application like ~ 0.001" so I wasn't expecting it being this bad.

I put a DTI on the arbor collar, not that it means much, but its within 0.001" & the shank itself seems nicely ground & under 0.0005" right adjacent to collect lip. I'm holding in an accurate R8 collet for testing. This particular arbor threads into the chuck body as opposed to typical taper mount.

Since its rather useless for intended purpose of teeny drills & confined chuck space in certain applications, I'm wondering out loud about drastic measures. If I unscrewed it & turned down the threads a bit so it had just enough lateral play to compensate the 0.004" back out. Then coat the threads with retaining compound or filled epoxy, establish runout back to zero & let the adhesive set up. The gaps are so small I really don't think it will come apart. well.... ever 
Viable plan or wishful thinking?


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## darkzero (Apr 23, 2019)

No idea on a fix but was it brand new? 4 thou is surprising cause LFA chucks are usually pretty nice. I've seen some with very low runout.


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## Canus (Apr 23, 2019)

Could you possibly chuck a piece of drill rod in the chuck then mount it in a lathe, with the drill rod in the lathe jaws, and machine the shank?


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## petertha (May 2, 2019)

That thought crossed my mind too. It would probably have to be toolpost ground & it would probably no longer fit a 0.5" R8 collet. A smaller collet isn't the end of the world but maybe throwing good money after bad. That's why I thought I'd try & confine the fudging to the chuck/arbor thread section. I have to get it apart & don't have a thin wrench so have to fabricate something. 

If I would have known it was going to be a trouble maker I would have gotten something like an ER11 collet chuck. The specs are probably better with a decent quality name. Min collet size is 0.5mm I believe so small enough for what I want to do.


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