# Jacobs Drill Chuck Runout--



## Bob V (Jan 2, 2016)

Hi All, and Happy New Year,

I have an old Van Norman mill with spindle runout under .001.
To tool this up over the past 4 months, I bought a Jacobs chuck,  Model 34-33C and i got a new arbor  (JT33 to 2M) adaptor to adapt to my spindle taper: Van Norman Style "C".
All of this fits together just fine-- but with a rather long "stack", even without a drill bit in the chuck.

I've read quite a bit on forums about Jacobs chuck runout-- and Jacobs says my chuck should have no more than .004 TIR at half capacity-

.004 seems like a lot of runout-- and doesn't include runout of the spindle and stack of adaptors to the chuck.-- not to mention that twist drills are frequently not that straight (I'm new to this but this is what I've read.)

Anyways, my question is: how do you drill a "straight hole" (where it's supposed to be and the correct diameter) with this kind of setup?  .004 plus all the other stacked runouts could really add up-- so what do guys do to get the right size hole in the right place?

--Hope I made this question clear enough! please tell me if it's not clear!
Thanks
Bob


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## Bill Gruby (Jan 2, 2016)

What would really help here is apicture of the set-up and the parts. I don't own a Van Norman so without the pics it's hard to help.

 "Billy G"


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## Techie1961 (Jan 2, 2016)

When Jacobs mentions the max runout, they're referring to the manufacturing tolerance, not necessarily what yours has. You are right that there might be a compounding of runouts happening but you can also use this to your advantage. I would try indexing the different components one by one to see where you get the best concentricity. Index each component at 90 degree increments and recheck. Use a gauge pin or long dowel pin for your checks. Also check the jaws of the chuck. They may be worn at the tips which is common. A rebuild kit from Jacobs would fix that nicely.


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## Bill Gruby (Jan 2, 2016)

Rebuild kit, why, this is a brand new chuck not an old one. If anything get a replacement.

 n
"Billy G"


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## Techie1961 (Jan 2, 2016)

Bill Gruby said:


> Rebuild kit, why, this is a brand new chuck not an old one. If anything get a replacement.
> 
> n
> "Billy G"


I wasn't aware that it was a new chuck. He said that he bought one but didn't say if it was new. Of course if it is new, and doesn't meet the manufacturers tolerances, it should be returned.


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## Bob Korves (Jan 2, 2016)

+1 on checking each component separately for runout, marking the high (or low) spots, and then using the variations to cancel each other out.  Put a high spot and a low spot together and they work toward cancelling each other out.  It is a simple way to achieve good (or at least better) accuracy while using less than perfectly accurate tooling.


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## Bob V (Jan 2, 2016)

Bob Korves said:


> +1 on checking each component separately for runout, marking the high (or low) spots, and then using the variations to cancel each other out.  Put a high spot and a low spot together and they work toward cancelling each other out.  It is a simple way to achieve good (or at least better) accuracy while using less than perfectly accurate tooling.


I don't actually know how to get the arbor out of the Jacobs chuck--so I can't check the arbor independent of the chuck.
How do I get the arbor out of the chuck?? the drill end of the chuck (with the jaws) is a blind hole--


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## randyjaco (Jan 2, 2016)

I wouldn't worry about . 004"  runout for a drill. If you start the hole with a center punch and use a centering drill, drill bits up to 1/4" will flex enough to keep your hole straight.

Randy


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## joshua43214 (Jan 2, 2016)

You remove a chuck with a Jacobs Chuck wedge
http://www.use-enco.com/CGI/INPDFF?PMPAGE=480&PMCTLG=00
Other wise you have to drill through the bottom of the chuck and drive the arbor out with a drift.

You have brought up an important point about drills. The short story is that drills do not make accurate holes.
If you want to drill in a particular spot, then start with a spotting drill. A spotting drill will carve a vee bottomed hole that is centered under the spindle axis, and unlike a center drill, the vee will engage the outside of the drill bit and make the drill start with no chatter in the correct spot.
If you want a hole a certain size, then you have to ream or bore.


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## brino (Jan 2, 2016)

Bob V said:


> Anyways, my question is: how do you drill a "straight hole" (where it's supposed to be and the correct diameter) with this kind of setup? .004 plus all the other stacked runouts could really add up-- so what do guys do to get the right size hole in the right place?



Joshua has it.....If you need a very accurate hole you do not drill it.

I am not familiar with your mill, but for the most accurately sized holes:
-keep the extra stuff between the spindle and the tool to a minimum; each adds play
-don't use a drill chuck, perhaps collets if your spindle accepts them
-don't use a drill bit (a bad sharpening can throw them off wildly)
-use a large diameter(stiff) new end mill (be sure it is an "end-cutting" cutter!)
-if possible ream to final size

It could also be done with a boring head on the mill or boring bar in the lathe.

As for "on location":
-on the mill I use an edge finder and the dials on the feeds to set location (a DRO would be even nicer!)
-search "tool makers buttons" to find another accurate way to position holes
-a co-ax indicator or even a wiggler can help get on centre.
-I use a centre punch like this to mark accurately to my scribed lines: http://www.leevalley.com/en/wood/page.aspx?p=45502&cat=1,180,42311

However, with all that said, normally for the accuracy I need a drill is fine.
-brino


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## mksj (Jan 3, 2016)

Agree with Bob Korves on trying to use the any runout between the arbor and the chuck to cancel out each other (or consider a keyless chuck with an integrated arbor). I recently had a Jacobs 14N which I bought used, but was in very good condition. I was surprised that it had a TIR of 0.005". I took off some high points on the jaws, and then  milled a wedge tool out of some 1/2" aluminum. Took some effort, but was able to separate the chuck and the arbor without any damage. Put the arbor in the lathe and used some very fine grit sandpaper to clean the mating surfaces, then put the arbor in a 4J independent chuck and zeroed the runout. I put some 1/2" precision rod in the Jacobs chuck and hand mounted it to the JT3 arbor. I then kept indexing the Jacobs chuck to the arbor until I got the lowest TIR from the precision ground rod, the TIR was now 0.0005".  When I pressed them together and mounted in my mill, the TIR was~ 0.0008" with 1/4 and 1/2" rod. Although you can measure the drill chuck and arbor separately and estimate what might give the least TIR, that did not give the lowest TIR, most likely because of slight difference in taper and the interference fit. Only by indexing the two, and measuring them together at difference points, was I able to get the minimum TIR with both pieces joined. 

As others have mentioned, using a short stiff center drill to locate the hole really helps in decreasing the drill  from walking. Using shorter screw machine drills with 135 degree flutes helps, a lot also depends on the material and final size hole. I usually use an end mill to finish a larger hole after stepping the hole larger with standard drills. As of recently, I have had issues with end mill bits causing over sized holes in some materials, because they do not clear the chips as effectively as a good sharp twist drill. Good lubricant and clearing the chips is important. You may use a chuck reamer if you need a high degree of accuracy or slightly over or under size diameter. I find that an ER-32 collet holder to have the least run out in my mill, and after that, a keyless drill chuck with an integrated arbor. There are also factors of how well your mill is aligned and rigidity.


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## Bob V (Jan 3, 2016)

mksj said:


> Put the arbor in the lathe and used some very fine grit sandpaper to clean the mating surfaces, then put the arbor in a 4J independent chuck and zeroed the runout



First, thanks to everyone--I've learned a lot.

*mksj  -- *how did you "put the arbor in the lathe" for sanding it?-- the arbor I have has tapers on both ends. 
            --again, how did you "put the arbor in a 4Jchuck and zero the runout"?
    --sorry if these are obvious to you and not to me-- but at my stage-- just about everything is new-----


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## Techie1961 (Jan 3, 2016)

Bob V said:


> I don't actually know how to get the arbor out of the Jacobs chuck--so I can't check the arbor independent of the chuck.
> How do I get the arbor out of the chuck?? the drill end of the chuck (with the jaws) is a blind hole--


If you want to remove the chuck (but I don't think you need to in this case) I have had luck with this technique.

If there is a shoulder on the arbor, you can use two pieces of aluminum that are the same thickness as the gap between the back face of the chuck and the shoulder on the arbor. Mount one piece of aluminum in a vise and place the chuck/arbor over it. Put another piece over the top and hit it with a hammer a few times. When the aluminum deforms, it will push the pieces apart with a sort of hydraulic action.


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## mksj (Jan 3, 2016)

Hi Bob,
Alignment between the arbor and the drill chuck can be done in the lathe or in your mill. In either case, I manually turn the spindle to check the TIR. Be very gentle in clamping the arbor in a lathe, just lightly tighten the lathe chuck jaws as not damage the arbor.  I used the lathe because I wanted to check the arbor and Jacobs chuck TIR separately and clean up some marks on the arbor. If using the mill just find the arbor to drill chuck position that gives the least TIR and then mark the two (see red marker I used). Probably lots of ways to do this.
Mark

Polishing up the arbor.



Setting up the arbor to ~0 TIR with the 4J, I actually check it at different points on the taper.



Checking the drill chuck TIR, the Jacobs chuck is hand tightened to the arbor. I keep indexing (turning) the Jacobs chuck relative to a fixed position on the arbor until I get the minimum TIR position. I was actually amazed that I could reduce the TIR of the Jacobs chuck to under 0.001" when both separately measured worse.


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## Paul in OKC (Jan 3, 2016)

Couple of thoughts. Using a center drill will give you a pretty accurate placement for your hole. The run out may effect the final diameter at the top of the hole making it slightly larger. As said above, smaller drill bits will flex a bit. Drill chucks can be like 3 jaw lathe chucks. Use all three holes for the chuck wrench to tighten, and there may be a 'magic' hole or combination that puts things in line.


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## Jason Annen (Jan 3, 2016)

Is it a brand new Jacobs?  We got one at work and the runout was .016", and that's not a typo.

Jason


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## Bob V (Jan 5, 2016)

mksj and everyone else- thanks!

Today I just turned one of the components of my mill/drillchuck stack 180 degrees, and the runout went from 12 thou to one thou!
Thanks for all the "tips and tricks".
JA  did you guys return that chuck with .016 TIR?
Bob


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## Jason Annen (Jan 5, 2016)

Replaced the Chuck with an older one found in a draw and sent the new one back to the crib.

It's probably sitting on a shelf somewhere now.

Jason


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## brino (Jan 5, 2016)

Bob V said:


> Today I just turned one of the components of my mill/drillchuck stack 180 degrees, and the runout went from 12 thou to one thou!



That's quite a lot!
Is it reproducible or was there some debris in the tapers?
-brino


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## Big Bore Builder (Jan 5, 2016)

There is merit in buying the ball bearing super chuck.

As other posters have said, drilling is not accurate.

And inexpensive arbors add to the run out.

One question in my mind is how was the run out of the old Van Norman mill determined.    May not be much at the beginning of the quill opening, but back in the quill where the small end of the MT is could have a ding, dirt, chip, burr, or whatever.

AND! what is the real taper of the Van Noman the OP has?     Is there another adapter in place?    NO. 2 MT does not appear to be the original spindle taper, I am guessing a C to No 2 adapter is in use.   

Old collets and adapters wear and suffer from abuse.  

We need photos!

*Spindle Tooling For Van Norman Milling Machines*
Van Norman milling machines used a number of different spindle tapers. In addition to standard 30, 40, and 50 tapers, there are two proprietary Van Norman tapers. The #6and #12 mills, as well as some #16 mills, used the Van Norman "C" taper. This taper is more commonly known as "5V", which is the Hardinge designation. The other Van Norman taper is "2", which Hardinge calls "50V". It was used in some 22L mills, and possibly others. Collets and tooling made by Van Norman will be marked "C" or "2", while items made by Hardinge or others will probably be marked "5V" or "50V".



The next drawing shows a milling arbor for a 5C spindle. The main difference is the addition of key slots that engage the keys on the front of the spindle. This drawing is also based on a drawing I got from Orrin Iseminger, as well as measurements made on my own machine.
(UNDER CONSTRUCTION - Drawing not done yet)



Page design and contents copyright 2002 by John Kasunich. All rights reserved. These pages are presented as a free service for owners and prospective owners of Van Norman milling machines. The information on these pages is believed to be accurate but is not guaranteed. Please contact me if you find errors, have more information, or just have comments about this site or Van Norman machines.
Thanks for visiting.


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## mksj (Jan 5, 2016)

Bob V said:


> Today I just turned one of the components of my mill/drill chuck stack 180 degrees, and the runout went from 12 thou to one thou!



Sweet! The newer Jacobs drill chucks from China are quite poor by reports from others. At the price you pay for them, they should have better QC (and quality), but one needs to include the arbor in the equation. I use a Z-Live integrated  arbor keyless 3MT chuck on my lathe tailstock, and it works like a dream. So it seems hit or miss.  On the mill I like a keyed drill chuck so tooling does not fall out of the chuck when reversed, like threading. I need to get a bigger drill chuck, probably a ball bearing 5/8" Llambrich chuck.


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## Bob V (Jan 6, 2016)

Hi John K, and thanks for the input,
I've finally taken pictures of my setup-- yes there is an adapter in the setup as can be seen in the photos and as I indicated in my first post about this.
-- I did get the runout  down to less than one thou at the gage pin in the chuck in the pic when mounted in my old mill.
I plan to use dome dykem blue to try to see if there are any burrs or whatever up in the spindle-- but I think the inside of the spindle is OK.
The collets (nearly a full set came with the mill) are in pretty rough shape: quite a few are galled inside and I'm trying to see if I can rehab any of these-- would appreciate any tips on this--
It seems my major hurtle is the lack of availability of 5c collets at a reasonable price--

Thanks again for all the help--
Bob


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## EmilioG (Apr 27, 2017)

The drill chuck jaws may be the culprit in some cases.  I've read in Lautards MBSR #1, that using a ceramic rod, 1/4" dia. to lightly
grind the jaws, can help in reducing TIR.  By lightly closing the jaws around the abrasive rod while it's spinning in the lathe, this is supposed to
grind the jaws ID evenly.  Not sure if I would do this to a new set of jaws.  I have back up sets of the older USA Jacobs 14n rebuild kits.
May be worth a try on slightly worn jaws?  Another source of wear on a Jacobs, is the sleeve. The ID bearing surfaces wear over time.  I've also read that using a .0001" indicator is better for checking TIR, along with a dowel pin size that is half the chucks capacity. (Jacobs 14n- 1/4" dowel pin).  Precision dowel pins are supposedly the straightest pins one can easily find and use.


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## Wreck™Wreck (Apr 27, 2017)

It is a DRILL CHUCK, these are commonly used for DRILLING rough holes at rapid metal removal rates. If you require a very high level of diametral accuracy do not use one for such purposes.


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