A Machinist Question....

[1FATGMC]

This past year I got a keyless chuck for my mill/drill.  I love it and would like to also get one for the tailstock of my lathe and for the new mill I just ordered.  The one thing that has been a problem with the new chuck and the old chuck is that occasionally when drilling with a bit in the 3/4 inch to 1 inch size the bit will grab the metal and the chuck will spin on the R8 tapered adapter.

I can get the new keyless chucks with either 6JT or 33JT mounts and I can get both a R8 to 6JT or R8 to 33JT adapter for the mill and a 3MT to 6JT or 3MT to 33JT for the lathe tailstock.  Is one of these tapers less prone to slipping than the other??

Thanks,

Sum

[C9]

This past year I got a keyless chuck for my mill/drill.  I love it and would like to also get one for the tailstock of my lathe and for the new mill I just ordered.  The one thing that has been a problem with the new chuck and the old chuck is that occasionally when drilling with a bit in the 3/4 inch to 1 inch size the bit will grab the metal and the chuck will spin on the R8 tapered adapter.

I can get the new keyless chucks with either 6JT or 33JT mounts and I can get both a R8 to 6JT or R8 to 33JT adapter for the mill and a 3MT to 6JT or 3MT to 33JT for the lathe tailstock.  Is one of these tapers less prone to slipping than the other??

Thanks,

Sum

I'm sure you've made sure the taper mating surfaces are clean and dry.
Common white blackboard chalk seems to help.
Powder some up and rub it on the taper before installation.

If you have a soft brass hammer it can help to give the chuck a firm swat when installing it on the taperered adapter or into the mill taper.
Make sure the chuck jaws are retracted and you're just striking the body of the chuck.
Be aware that some brass alloys are hard enough to dent steel.

A yellow plastic or even a rawhide hammer can help, but if you're using a brass hammer don't get too carried away with the striking force and hit the chuck body squarely when you hit it.

If you've got some vibration going on, that will loosen the tapered adapter in short order and either the chuck will fall off - not the usual - or the mill end of the tapered adapter will come out, which is what usually happens.

Vibration can occur for several reasons, but one that can get you is an unevenly sharpened twist drill which is cutting on one side only.

Slow the speed down for the big drills, that also takes a lot of vibration out.

[1FATGMC]

Thanks Jay,

I clean the surfaces good with brake cleaner and then dry them good, but haven't tried the chalk.  I have used a rubber dead blow on them also. I do slow the speed down and that is one of the things I really like about the mill/drill I have is that it is gear drive and so changing speeds is just the flick of the levers on the front.

This doesn't happen often, but though if one of the two tapers that are available was better than the other I'd go with it as the adapters cost the same.

c ya,

Sum

[unklian]

Those drills are too big for a keyless chuck.

They should be held in a collet.
Turn the shanks down if necessary.

[1FATGMC]

Those drills are too big for a keyless chuck.

They should be held in a collet.
Turn the shanks down if necessary.

I'll try that.  They are turned down to 1/2 inch.  Problem is that since the table on this mill/drill is not on a knee if I go from the chuck to a collet I loose my position when I have to lower the head.  The new mill I ordered is a full size mill with a knee so I wouldn't have that problem.  The holes are normally only through 1/8 or 3/16 inch material unless I'm drilling a hole in round stock on the lathe.  Once I get over 1/2 inch with the mill or lathe I usually just step the cuts up in 1/16 inch intervals with the bits and that is one reason I like the keyless chucks as I can change bits so quick with them.

I guess the question I still have is, does one of those tapers (6JT or 33JT)have an advantage over the other in anyway?

c ya,

Sum

[Pete]

I have 3 chucks with 33jt taper. I put locktite on them when assembling.
I have never had one slip..If you need to remove it just warm it to about 200 degrees and the locktite will soften.
I use a brass hammer like C9 suggested.

[1FATGMC]

I have 3 chucks with 33jt taper. I put locktite on them when assembling.
I have never had one slip..If you need to remove it just warm it to about 200 degrees and the locktite will soften.
I use a brass hammer like C9 suggested.

Thanks, good tip, I didn't ever think about the locktite.  I don't  need to take them off the adapter, so that is a good idea.  Do you remember if you used the low temp red or the blue.

I'll also get the 33JT taper,

Sum

[Dave]

Super glue works also..
Dave

[Pete]

Red

[C9]

No evidence to back it up, but it seems that the taper with the most gripping area would stick together the best.

Shallower angles in other words.

My keyless chucks are threaded and the R8s not going anywhere due to the threaded rod on the mill.

Pretty sure the drill press is 33JT and it hasn't slipped since I swatted it with a brass hammer.

The lathe has a Jacobs 5/8" key-type chuck that threads onto a MT2 arbor.
It does pretty good drilling with big drills and in fact I have a 1 1/4" and I think a 1 1/2" I need to turn down so they will fit the Jacobs chuck.

I use the Jacobs on the lathe to hold taps sometimes, but when they get over 1/4" I use a standard tap handle - not the T style, regular double bar type - retract the jaws on the Jacobs chuck so it's flat and use that to make a square alignment or if the tap is center drilled I use a dead center to keep the tap aligned.
Set the lathe quick-change to the thread pitch, set a piece of wood on the compound and let the compound resist the torque of the tap handle while you slide the tailstock by hand to keep the tap handle flush with the Jacobs chuck so as to retain alignment.

A material and time-saving trick is to use a large hole saw to start the cut for a large bore in thin material, the pic shows 1/4" thick aluminum being hole sawed - at slow speed - prior to using the boring bar to get to a 2 1/2" bore for a fuel tank flange.

[1FATGMC]

Some good ideas there, thanks,

Sum

[Leon]

When I put mine together, I put the arbor in the freezer and the chuck in the oven to about 200 degrees.  When I took them out and shoved them together, whacked with a soft mallet.  Now I doubt I could get them apart if I tried.

[unklian]

Some of the No Name Brand tapers don't match real well,
so they tend to come loose when you really need them.

[Silbefeil]

This past year I got a keyless chuck for my mill/drill.  I love it and would like to also get one for the tailstock of my lathe and for the new mill I just ordered.  The one thing that has been a problem with the new chuck and the old chuck is that occasionally when drilling with a bit in the 3/4 inch to 1 inch size the bit will grab the metal and the chuck will spin on the R8 tapered adapter.

I can get the new keyless chucks with either 6JT or 33JT mounts and I can get both a R8 to 6JT or R8 to 33JT adapter for the mill and a 3MT to 6JT or 3MT to 33JT for the lathe tailstock.  Is one of these tapers less prone to slipping than the other??

Thanks,

Sum

any drill over 1/2" should be a taper drill which fits your  Drill head taper and tail stock etc. Using turned down drill shanks is asking for trouble with inaccurate work.
Buy quality taper shank drills which fit your tapers. mark them with blue and check the taper is correct before use, If there are high spots etc use a fine lapping paste to to get the taper to fit correctly.
A correctly fitting taper should NEVER have to be hammered home!.
A drill should be just pushed into the taper and must be capable of sitting by itself.
Any normal drill made in the last 180 years will have a slot to insert your taper drift to release the drill and, to release it from the tail stock ,this  should be designed to pop it out when the screw is returned back fully.
Keyless chucks are for cheap quick work,something you should avoid if you want to make quality stuff with your machine.
if I had been caught wacking a machine with a hammer when I was  serving my Apprenticeship ,I would have had the hammer used on me...