My Drill Chuck Keeps Falling Off

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CFLBob

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This is the drill chuck I use on my big milling machine. The mill has an R8 taper (Grizzly G0704) and when I was setting up tooling for it, I bought a nice chuck from Little Machine Shop for it. The chuck has a JT33 taper and I bought an R8 to JT33 adapter - from LMS, I think.

If it matters, the adapter is branded South Bend and the chuck is Harvest. The chuck is 1/32" to 1/2" and I've not seen many of those, so I'd like to keep it.

For the last several months, the chuck has been falling off the adapter more and more often. I've cleaned both surfaces with a rag, but that has apparently done nothing because the problem keeps getting worse.

How can I fix this? I can't push the R8 adapter into the chuck harder than I've been doing.


Bob
 

jack620

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How can I fix this?
You can try chilling the adaptor in the freezer and warming the chuck in the oven (say 100C/210F). Make sure the chuck jaws are retracted inside the body. Using an oven mitt, hold the heated chuck vertically on a block of wood and drop the chilled adaptor into it. Give the adaptor a few good taps with a soft faced hammer. This will give you a tight shrink-fit.

I've done this a couple of times and never had a chuck come loose.
 

SmithDoor

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Clean all oil off both parts.
Then putting both together.
Tap the Chuck on the R8 using a brass hammer and a anvil. Do not try tapping in the mill.

Dave

This is the drill chuck I use on my big milling machine. The mill has an R8 taper (Grizzly G0704) and when I was setting up tooling for it, I bought a nice chuck from Little Machine Shop for it. The chuck has a JT33 taper and I bought an R8 to JT33 adapter - from LMS, I think.

If it matters, the adapter is branded South Bend and the chuck is Harvest. The chuck is 1/32" to 1/2" and I've not seen many of those, so I'd like to keep it.

For the last several months, the chuck has been falling off the adapter more and more often. I've cleaned both surfaces with a rag, but that has apparently done nothing because the problem keeps getting worse.

How can I fix this? I can't push the R8 adapter into the chuck harder than I've been doing.


Bob
 

CFLBob

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Thanks Dave, and Jack620.

I will attempt both. Clean thoroughly with solvent to make sure there's no grease, and then try the hot chuck, frozen adapter method.
 

dnalot

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If the above does not work lap the chuck to the adapter and then clean and try again. I had this problem before and lapping did the trick.

Mark T
 

BaronJ

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Hi CFL Bob,

You will probably find that both parts are very hard so my preference would be to lap them together. It doesn't take much of a difference in the taper angle for them to loosen.

You could also blue them and actually see where the points of contact are.
 

ShopShoe

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Second on testing the fit with the blue. I had that problem with my old Delta drill press and I found the fit poor. Once I cleaned things up it stayed on.

--ShopShoe
 

WOB

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If the fit is reasonably good, put a dab of Loctite( any kind) on the degreased male taper and tap it into the chuck body with a soft hammer. 24 hrs. cure time and problem solved.

WOB
 

packrat

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The best way to fix the problem is with a Abrecht drill chuck with a R8 shank {not cheep} or go with a straight shank and use a collet in the R8 spindle
to hold the straight shank...and do away with the Morse taper or the 33JT
 

SmithDoor

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The down side to Loctite is need to remove the Chuck it is real pain.

Dave

If the fit is reasonably good, put a dab of Loctite( any kind) on the degreased male taper and tap it into the chuck body with a soft hammer. 24 hrs. cure time and problem solved.

WOB
 

bluejets

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How can I fix this? I can't push the R8 adapter into the chuck harder than I've been doing.
Bob
Fist check would be to make sure it's not bottoming out in the adaptor.
 

dwentz

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I would start with testing the fit with highspot blue or a smoke test. That will tell you how good or bad the fit is. If they are not perfect you can lap them in a bit and then do the hot and cold thing. You did not say what operation you are doing when the chuck was coming off. If you are using the chuck to hold end mills or other tooling and applying side pressure it is common for them to separate, due to the side pressure.
 

CFLBob

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For some reason, the forum never let me know these updates posted yesterday, just today. I came back and see several posts talking about checking with dye. I don't know what a smoke test is.

I tried the hot/cold approach yesterday but haven't tested it yet. I put the adaptor into my freezer set to 0F, and put the chuck in a toaster oven in the shop set to 200. I left both in those places almost a full hour.

Dale, this has been exclusively drilling. No end mills, and no cranking the work sideways into the chuck. I'm not sure when it started, but I'm rather sure it has gotten worse. The pair was bought toward the end of '14.

If the fit doesn't work, I'll start looking at the blue Dykem on the adapter. It will certainly be easier to see issues on that than on the inside of the chuck.
 

BaronJ

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For some reason, the forum never let me know these updates posted yesterday, just today. I came back and see several posts talking about checking with dye. I don't know what a smoke test is.
The "smoke" test is using a candle flame to make soot on the part !
When the two parts are fitted together the soot gets rubbed off where the parts make contact.

I don't think Dykem will work for this, you need engineers blue. A really thin smear will do.

I tried the hot/cold approach yesterday but haven't tested it yet. I put the adaptor into my freezer set to 0F, and put the chuck in a toaster oven in the shop set to 200. I left both in those places almost a full hour.

Dale, this has been exclusively drilling. No end mills, and no cranking the work sideways into the chuck. I'm not sure when it started, but I'm rather sure it has gotten worse. The pair was bought toward the end of '14.

If the fit doesn't work, I'll start looking at the blue Dykem on the adapter. It will certainly be easier to see issues on that than on the inside of the chuck.
 

dwentz

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Correct on the smoke test, a candle or a wooden stick soaked in oil works, that how I was taught to do it. Soot one of the parts and see what is removed. Dykem is not what you want, Prussian Blue Fitting Compound by Permatex or Dykem Hi-Spot Blue are the two most common. Warning on the prussian blue. It will leak from the container once open and make mess that is impossible to clean up. Put in a baggie or small sealed container after opening the tube. Not sure what it is with this stuff, but it defies all the laws of physics with its ability to escape the tube, or get on things you do not want it on. I have observed this phenomenon many times, it does not like to be contained!!!
 

SmithDoor

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Any time I machine a tapper for morse tapper or Jacob tapper I use Prussian Blue for fitting.
I have also use Prussian Blue for scraping bed ways too.

Dave

Correct on the smoke test, a candle or a wooden stick soaked in oil works, that how I was taught to do it. Soot one of the parts and see what is removed. Dykem is not what you want, Prussian Blue Fitting Compound by Permatex or Dykem Hi-Spot Blue are the two most common. Warning on the prussian blue. It will leak from the container once open and make mess that is impossible to clean up. Put in a baggie or small sealed container after opening the tube. Not sure what it is with this stuff, but it defies all the laws of physics with its ability to escape the tube, or get on things you do not want it on. I have observed this phenomenon many times, it does not like to be contained!!!
 

BaronJ

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Warning on the prussian blue. It will leak from the container once open and make mess that is impossible to clean up. Put in a baggie or small sealed container after opening the tube. Not sure what it is with this stuff, but it defies all the laws of physics with its ability to escape the tube, or get on things you do not want it on. I have observed this phenomenon many times, it does not like to be contained!!!
Tell me about it ! I bought a tin of Engineers Blue. Never been opened. It must have sat in that tool box for a year or so. When I came to use it the tin and part of the tool box bottom was covered in the stuff.
 

CFLBob

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I did eight operations with the chuck by making a couple of countersunk holes in a piece of scrap today and had no trouble with the chuck at all.

Two spot drills, two small drill holes, two full-sized holes and two countersinks. All of these things were bigger than what I was working on when I finally said I've got to fix this.

I couldn't get through one set of operations the other day. I couldn't countersink a drilled hole. The hole was smaller than 1/8" dia. (0.116) and a 3/8" countersink. Almost as soon as countersink touched metal, I could hear the sound change and the chuck would go loose on the adapter.

I can't swear it's all fixed, but it's better than it was.

Thanks for the suggestions on Prussian blue. I ordered some lapping compound and if I have more trouble, I'll go that route.
 

Saddo

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Drill chucks should only be used for drilling. Hope your not using it for milling as under side forces they will ultimately fall off anyway.
 

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