Drill chuck runout.

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Hukshawn

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I'm sure this topic has been beat to death previously, a quick search didn't return anything useful, however.

I have a 16N Jacobs drill chuck. Older. The jaws are decent, but definate signs of wear. I filed to remove burrs, etc.

Before I consider a rebuild kit, what is realistic for TIR?
I get different readings depending on how I clamp a drill, or end mill, or center drill. How deep I insert the piece, how hard I tighten, etc.
The most runout I read was nearly .017", which is just downright unacceptable to me, and I managed to get a 1/2" carbide endmill to run at .002". All depending on where the endmill sits in the jaws, how hard I clamp, etc. So the jaws are definitely worn.

I'm just hobby, but the weeble wobble bothers me. I tried running a reamer last week with less than desirable results. (Quite possibly also due to an old worn out reamer, but it wobbled none the less)

I know I've read several times before that it's nearly unheard of to have a drill chuck run dead nuts in a mill. So, how high should I really be setting the bar...? Before I go and spend over 100$ on a rebuild kit.
 
Hi Shawn,
acceptable runout may be different for each person using the drill chuck
IMO you are good if you have less than .010" runout,
but i'm sure i have a drill chuck or 2 that have greater runout due to having the snot kicked out of them for 50 years.

drilling, for the most part, is not a precision activity. sure where you place the hole may be in a precise location
but the size hole you want is almost never the same size as the drill you use.

if you know that your chuck has a lot of runout, simply select a smaller drill bit than the intended size and finish ream to specifications
 
Albrecht advertises that its chucks have the lowest run out in the industry. Their "precision drill chucks have a maximum run out of .04MM or .0015"
Jacobs advertises their plain bearing chucks to have a run out of .004", their super ball bearing chucks to have a maximum run out of .003", and their precision keyless chucks to have a run out of .0016"

All these specifications are made with arbors that have supposedly .0000 run out. I have several Jacobs super ball beating chucks. The best has a run out of .002, and the worst in .0035. All are in the 20+ year old range, and have never been rebuilt. I also have an Albrecht key less that's nearly brand new and it has a run out of .0015 as advertised.

If you can get to .004" on a rebuilt chuck I would say that's about as good as it's going to get.
 
Ten thou.. wow. Okay.

I think what bugs me most is when I use a center punch and try to have the center drill actually land in the punch hole and it's wobbling all over the place.

Someone spun a bit in the jaws pretty good at one point. There's actually a tiny shoulder. Maybe I'll try to file that out with a diamond file and see how I feel about it afterwards.
 
35 thou?!!?
Alright. I guess my standards are pretty high...
 
That Ebay rebuild kit is for a USA Jacobs 16n. $45 is a great price. These kits are rare. I see them going for $100 or more.
Huckshawn; Is your Jacobs a Hartford, CT USA 16n? I read that Jacobs chuck jaws can be trued up using a ceramic rod on a lathe, if the jaws aren't too bell mouthed. Brownells has the ceramic rods. Albrecht is the way to go if you want better precision. I get nice clean holes and round countersinking with my Albrechts, and Albrecht has plenty of spare parts available. Keep in mind, that the sleeve can also wear after a while, not just the jaws & bearing., which must come in a matched set or all bets are off.

And here's a NOS JAcobs USA 16n race/bearing balls kit: https://www.ebay.com/itm/USA-Origin...372140340109?_trksid=p2349526.m4383.l4275.c10
 
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