Drill Chuck run-out

[T Bredehoft]

Before istalling my refurbished Albrecht chuck on a new Jacobs arbor, I put the arbor in a 1/2" R8 collet, checked it with a .0001 Testmaster indicator. Spinning about 150 rpm the needle didn't move. Any. Haven't tried a pin in the chuck, yet.

 

[EmilioG]

Before istalling my refurbished Albrecht chuck on a new Jacobs arbor, I put the arbor in a 1/2" R8 collet, checked it with a .0001 Testmaster indicator. Spinning about 150 rpm the needle didn't move. Any. Haven't tried a pin in the chuck, yet.

The Albrecht chuck arbors are very concentric. Very well made and don't cost a fortune. You can get them on sale at Msc for about $45 for the 1/2" straight. I put 1/2" str. shank arbors on all of my drill chucks to make changes easy. Jacobs arbors?, I would only buy NOS USA made.

 

[ddickey]

I'm sure the arbor is original. It's 5/8".
The readings are completely inconsistent from close to the jaws to 6"s away. Just to make sure my ground rod was good I set it up on vee blocks and there is zero movement on the dti.
I'm thinking it is the arbor. Is it possible for them to be skewed?

I tried a few things earlier just to see. I know this is a bad way but I was bored. I put the ground rod in the lathe and clamped the drill chuck onto it. Then I indicated the arbor. Big time run-out and it got worse as I moved down. I did this to my Rohm as well. Then I tried my Taiwan made chuck which has a MT3 arbor. It had the least amount of run-out but what was interesting to me is as you moved the indicator towards the T.S. nothing changed unlike the other two.

Also I learned a few other things that the new guys, like myself, might be interested in. Do not put your straight shank arbor all the way into an R8 collet. From what I understand R8 collets grab mostly at the end. Make sure you pull your drill chuck out a little so there is a good clamping surface. Also, check your drill bit shanks making sure there are no raised burrs from spinning them in the chuck.

 

[EmilioG]

Could be the arbor or a combination, stack or error, including the jaws, worn jaw guides, ...I would start with a known, good arbor.
I use Albrecht Chuck removal tools to safely separate the chuck/arbor. If the jaws are worn or if someone spun a drill in the chuck, it could
increase run out. Could you post a photo of the Albrecht and it's arbor?

 

[ddickey]

Couldn't get a good shot if the jaws.

 

[mikey]

Hard to tell but the jaws look decent. When you had the hood off, did you happen to scuff (220 wet/dry sand paper works good) the inside of the hood where the jaws contact? If that area is too smooth the jaws can move around as you tighten the chuck so just make sure there is a visible scratch pattern in those contact areas. Also lightly lube the inside of the hood at those contact points; a tiny bit of oil on a Q-tip is enough.

I agree with Emilio that it is possible that the arbor is not in straight. My suggestion is to remove the arbor and make sure the taper socket in the back of the chuck is burr-free; same for the arbor. Before reinstalling the arbor, chuck it in the mill and check to see if it has any run out of its own. Indicate on the jacobs taper; if it is straight, it will be very straight.

When reinstalling the arbor, be sure you clean all traces of oil from the taper socket and jacobs taper. I suggest you use lacquer thinner for this, not alcohol. Retract the jaws of the chuck and place it on a solid surface - concrete or an anvil. Insert the arbor with a gentle twist and allow it to drop into the socket by gravity. Once it bottoms, protect the end of the arbor with a wood block and give it ONE light tap straight down on the end and that will seat it.

Then check your run out again.

 

[ddickey]

I did scratch the inside of the hood Mikey.
I'll try the other suggestions next week. Back to work tomorrow night.
Should I freeze the arbor?

 

[mikey]

No, please do not freeze it. You want to be able to remove it at need.

 

[EmilioG]

ddickey; The jaws look a little bell mouthed to me. It could be that someone spun a drill in the jaws. The arbor looks like a vintage Roehm. Albrecht arbors do not look like that one.

I would consider buying two new parts; a new Albrecht arbor and a set of new jaws. I know, it's a fairly large expense,($130 for both), but buying a used Albrecht can be a gamble.

Most people sell them on Ebay because they encountered a problem or abused it. Check Msc for a sale or Ebay for new jaws and Albrecht arbors. I would start with at least a new Albrecht arbor. ($60/5/8" Albrecht Str. JT33). Or, a set of new Jaws, if the arbor checks out.

 

[mikey]

I wrote a short piece on installing drill chuck arbors that might be useful to the new guys. There are many ways to install an arbor, from heat shrinking to epoxy to whacking it straight with a hammer. I like to think that a gentler approach works better.