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My Drill Chuck Run-Out

thestelster

Ultra Member
Premium Member
As an extension of the recent post by @van123d
on drill chuck recommendations, I decided to measure a few things. I have an Albrecht 1/2" drill chuck with and integral 5/8" straight shank. I purchased it 36 years ago to drill holes using my Ex-Cell-O 602 milling machine. I've used it to drill holes almost every day since I bought it. If I only drilled one hole a day, that would be 13,000 holes. I decided to measure the run-out of the chuck. But the drill chuck is held in the mill with a NMTB-40 ER40 collet chuck. So I measured the run-out inside the mill spindle, inside the collet chuck cavity, the collet gripping a 5/8" shaft, and then the Albrecht chuck gripping a 1/2" shaft ( at close to the drill chuck jaws; 2" further down, and then 4" away). Measurements were taken with a Mitutoyo tenths DTI. See the results below. Not too bad for an old, well used drill chuck.
 

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Susquatch

Ultra Member
Moderator
Premium Member
I decided to measure a few things

Excellent test @thestelster. It isn't really enough to measure a chuck alone. You need the full stack up of variables like you did.

My bride and I have been laid up with Covid for the last week. But I'll get out to the shop soon enough and do the same thing for a sample of the tools I have. I did a few tests a while back. It will be interesting to see if they have changed.

I have a few different makes of collets the same size that I can try too. It will be a good low effort activity I can do while recovering from covid.

Your chuck results were very interesting. It seems that it holds the test bar in good parallel alignment but off-center a thou. Not bad at all! Especially for an old girl like that!

Did you try remounting it to see if dust or something got in there and/or what happens if you turn it 90 or 180 degrees?
 

thestelster

Ultra Member
Premium Member
Excellent test @thestelster. It isn't really enough to measure a chuck alone. You need the full stack up of variables like you did.

My bride and I have been laid up with Covid for the last week. But I'll get out to the shop soon enough and do the same thing for a sample of the tools I have. I did a few tests a while back. It will be interesting to see if they have changed.

I have a few different makes of collets the same size that I can try too. It will be a good low effort activity I can do while recovering from covid.

Your chuck results were very interesting. It seems that it holds the test bar in good parallel alignment but off-center a thou. Not bad at all! Especially for an old girl like that!

Did you try remounting it to see if dust or something got in there and/or what happens if you turn it 90 or 180 degrees?
I did not try remounting the different connections ie. drill chuck, collet chuck, collet, shafts, but just made sure everything was clean and tightened to what I normally do.

The other interesting part is that the distance from inside the mill spindle to the furthest position I measured on the shaft held by the drill chuck is 10", which is a little more than 10x the run-out between those measured positions. Which leads me to believe,(though I could be completely wrong), that the connections/interfaces are quite accurate/precise/square.
 

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Susquatch

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Premium Member
Which leads me to believe,(though I could be completely wrong), that the connections/interfaces are quite accurate/precise/square.

Although not bulletproof, I agree. That a very reasonable and probable conclusion.
 

Susquatch

Ultra Member
Moderator
Premium Member
connections ie. drill chuck, collet chuck, collet, shafts, but just made sure everything was clean and tightened to what I normally do.

I'm just looking at the photo you posted here of your Albrecht chuck. How much of that assembly turns relative to the rest when you tighten down on a drill bit? Are you able to use one hand on the top half and one hand on the bottom to tighten/loosen the chuck by twisting in opposite directions?

If so, I'm even more interested in trying out an Albrecht chuck myself! That would solve my need for 3 hands.
 

thestelster

Ultra Member
Premium Member
I'm just looking at the photo you posted here of your Albrecht chuck. How much of that assembly turns relative to the rest when you tighten down on a drill bit? Are you able to use one hand on the top half and one hand on the bottom to tighten/loosen the chuck by twisting in opposite directions?

If so, I'm even more interested in trying out an Albrecht chuck myself! That would solve my need for 3 hands.
The top knurled ring is fixed with with the spindle. The bottom knurled body rotates to tighten or loosen the jaws. Yes, you could use two hands, twisting in opposite directions. Below are pictures doing it one handed!! I even did it with the spindle unlocked and in neutral. I did it as well with that small stub drill. No problem one handed. To remove, just a quick twist clockwise (viewed from above) and it's out.

Think of the keyless chuck for the mill as the equivalent of a QCTP for the lathe. I can edgefind, spot drill, small drill bit, large drill bit, countersink, power tap in lickity split time!
 

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PeterT

Ultra Member
Premium Member
The only time my keyless spins relatively free on its own is when the machine is in neutral. Even the high speed range there is enough mechanical drag. Low speed or any gearbox type mill should be sufficient drag.

So right hand on the drill, left hand on the chuck knurl. Position drill & tighten enough so it doesn't drop out. (I like to rotate the drill itself within the jaws to feel contact & ensure its not somehow cocked in the jaws.) With drill temporarily secure, hold the brake & tighten to desired level. It takes longer to type LOL
 

Susquatch

Ultra Member
Moderator
Premium Member
I managed to get out of bed today and went out to play in my shop for an hour. I decided it was a good time to test my drill chuck runout more rigourously.

My bare Spindle consistently measures less than a quarter of a tenth on my Mitutoyo 10ths dial test indicator. (0.000025) The needle barely moves. This is admittedly my best dial test indicator. The space between tenths lines is wide enough to be able to judge to a quarter tenth. I even decided to run the Mill at 5 Hz in low speed to see how reliably the dial indicator wobbled. It was pretty much bang on no matter where I tested it on the taper. Can't complain about that.

So I installed my R8 Drill Chuck. A Gerardi Spa Precision Chuck. That's when things went more squirrelly. I made the following chart.


Device Runout

R8 Spindle Alone 0.000025

End Mills in drill chuck
1/2 HSS 0.0020
1/4 Carbide #1 0.0038
1/4 Carbide #2 0.0010
3/8 Carbide 0.0012

Drill bits in drill chuck
Dormer 1/4 drill 0.00075
Dormer 3/8 drill 0.00050

R8 ER32 Holder
Holder Taper 0.00005

End Mills in ER32 Collets
1/2 HSS 0.0014
1/4 Carbide #1 0.0032
1/4 Carbide #2 0.0007
3/8 Carbide 0.0008

Drill bits in ER Collets
Dormer 1/4 drill 0.000075
Dormer 3/8 drill 0.000075

These all seemed to repeat quite well even removing, rotating, and re-installing the bits. Therefore I suspect that most of the runout is in the various bits themselves. I was particularly struck by the difference in runout between my good drill bits and end mill shanks. I should have tried some cheap drill bits, but didn't. Maybe another time.

So I spent some time hunting around for a rod or something with better precision. Everything I tested was either bad or inconsistent.

I don't have a set of precision dowel pins.

At this point, my head started spinning, so I went back to the house and crawled back into bed to write this note.

I'm almost certain I have some precision shafts somewhere.... I just need to remember where.

Tomorrow I'll try to evaluate my R8 to MT3 adapter and my MT3 Drill Chucks, and perhaps take a look at axial alignment using a longer rod - if I can find one.

I confess, that I am quite chuffed with the results using drill bits on both the GS drill chuck and the collets (the latter being better all the way around), and I guess I think the end mill results are pretty good too although I really don't think their runout matters that much given how end mills are used.
 

Susquatch

Ultra Member
Moderator
Premium Member
Think of the keyless chuck for the mill as the equivalent of a QCTP for the lathe. I can edgefind, spot drill, small drill bit, large drill bit, countersink, power tap in lickity split time!

I don't know what to say to all that except perhaps to express my jealousy.

My spindle has way less friction in it and my chuck prolly has way more. There is no place on my chuck to twist in opposite directions. And the Spindle protrusion out of the quill is way too little (and oily) to grab.

I did find that I can actually lock my Spindle up by engaging the back gear and the spindle hi speed clutch simultaneously. But it hurts my sensibilities to do that. So I'm still a 3 handed operation when using my chuck.

On the other hand, my collet chucks all have top and bottom sections and it's rather easy to twist them in opposite directions. So I can see how some keyless chucks would work well.

If I can ever find a decent keyed chuck for my mill, it will find its way home with me. I used to keep the key for the chuck on my mill/drill on an automatic retractor cable attached to the mill head. It was pretty darn convenient. I imagine it would work well on my mill too.
 

PeterT

Ultra Member
Premium Member
There is probably a way to measure the (low) torque required to tighten the keyless chuck. Maybe that's the issue if yours has more drag for whatever reason. I'll see if I can rig something up & measure mine for comparison.

The runout variation in runout is interesting. Hopefully your #1 is a bad outlier for whatever reason. I think the way to go for this type of thing is get some gage pins with defined specs. I've tried to find them individually but didn't land on a source. The import sets are reasonable cost for what you get, but they only span a certain range. Unless one does a lot of that kind of work, hard to justify.

End Mills in drill chuck
1/2 HSS 0.0020
1/4 Carbide #1 0.0038
1/4 Carbide #2 0.0010
3/8 Carbide 0.0012
 

Susquatch

Ultra Member
Moderator
Premium Member
Hopefully your #1 is a bad outlier for whatever reason.

Why do you say that Peter? It seems, reasonable to me. It's a shaft on an end-mill so I don't really expect it to be very concentric. There is also a flat ground in it for a keeper screw. I wouldnt be surprised if grinding the flat affected the concentricity above and below it.

There is probably a way to measure the (low) torque required to tighten the keyless chuck. Maybe that's the issue if yours has more drag for whatever reason. I'll see if I can rig something up & measure mine for comparison.

Yes, measuring the torque would be useful. The drag I feel on it with my hand isn't horrible. But it is higher than my Southbend chuck. And also very close to the torque required to turn the spindle. I can probably measure the spindle torque, but I'm not so sure about measuring the chuck torque.
 

PeterT

Ultra Member
Premium Member
Why do you say that Peter? It seems, reasonable to me. It's a shaft on an end-mill so I don't really expect it to be very concentric. There is also a flat ground in it for a keeper screw. I wouldnt be surprised if grinding the flat affected the concentricity above and below it.
Purely because everything else you tested in the chuck is significantly lower. Don't the other EM's have flats as well?
I don't know what you mean by a 'shaft on an end mill'.
 

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Susquatch

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Purely because everything else you tested in the chuck is significantly lower. Don't the other EM's have flats as well?

Ah, I see. You meant 1/4" #1 Endmill. I thought you meant first in the list which is the HSS end mill. This first hss end mill has the flat. Neither 1/4 end mill has a flat.

My guess is that the first 1/4" carbide shaft is bent a bit. It is an Ali special. I could actually check it on a runout fixture I have. The only reason I tried two of them is because I was shocked a bit by the first one. I thought about excluding it from the data but decided it was better to just tell it like it was and test it again.

I don't know what you mean by a 'shaft on an end mill'.

By shaft, I just mean the shank or the part of the end mill that gets held by a collet or a chuck. Basically, the part without any cutter edges on it.

I seem to going backward a bit with Covid so I'm not doing any other testing today.
 

jcdammeyer

John
Premium Member
I seem to going backward a bit with Covid so I'm not doing any other testing today.
Sorry to hear about the COVID issue. Given that my wife is a health care professional and likely exposed more often than others it's amazing we've missed it so far. One of her Pharmacy Technicians has had it three times and this time it's starting to look like he may be experiencing long covid. She had her 4th booster in August. I had mine last week Tuesday. I don't wish this bug on anyone.
 

Susquatch

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Premium Member
Sorry to hear about the COVID issue. Given that my wife is a health care professional and likely exposed more often than others it's amazing we've missed it so far. One of her Pharmacy Technicians has had it three times and this time it's starting to look like he may be experiencing long covid. She had her 4th booster in August. I had mine last week Tuesday. I don't wish this bug on anyone.

Thanks John. I don't wish it on anyone else either.
 
I seem to going backward a bit with Covid so I'm not doing any other testing today.
Sorry to hear this, having travelled that path a couple times now, all I can suggest is that you take it easy, especially as you start feeling better. Long covid seems to take hold if you over do things for the first while, not sure how long it sticks around, but I am still feeling the effects almost a year in..... Take care my friend.
 

Susquatch

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Premium Member
Long covid seems to take hold if you over do things for the first while, not sure how long it sticks around, but I am still feeling the effects almost a year in.....

Scary thought...... I'll try hard to heed your advice.
 
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