Author Topic: A Machinist Question...  (Read 12666 times)

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Offline Sumner

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A Machinist Question...
« on: May 11, 2008, 10:45:05 AM »
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

Offline aircap

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Re: A Machinist Question...
« Reply #1 on: May 11, 2008, 12:08:18 PM »
In my years of experience as a tool and die maker, keyless chucks work best for smaller drills in production situations, where timed saved is important.
If you are doing fabrication, stick with the keyed chuck - you can get the drills tighter in the chuck.
Don't forget to tighten all 3 holes, it makes a difference!

(I didn't even know keyless chucks went up to 1 inch)
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Offline Glen

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Re: A Machinist Question...
« Reply #2 on: May 11, 2008, 12:24:54 PM »
Turned down shanks, and they bend easy as well. I agree a keyed chuck is the best way to go.
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Offline Sumner

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Re: A Machinist Question...
« Reply #3 on: May 11, 2008, 03:51:36 PM »
Turned down shanks, and they bend easy as well. I agree a keyed chuck is the best way to go.

Glen is right the bits are turned down to 1/2 inch.  Sorry, but you aren't going to get me to give up on the keyless chucks, I love them.  I have 2 keyed chucks and I'm not going back.  The problem, when it occurred, was not the bit turning in the chuck, but the chuck turning on the adapter.  Not often at all.  A little while ago a friend says he locktites his on and gives them a smack with a brass hammer and never has had them turn, so I'll try that.

The two new keyless that I'm going to order also have a spanner wrench that comes with them if you really want them tight on the bit.

Thanks for the tips, guys,

Sum

Offline Peter Jack

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Re: A Machinist Question...
« Reply #4 on: May 11, 2008, 04:03:05 PM »
I keep a couple of strap wrenches handy so I can loosen them after a larger size has been used for heavy drilling. Their self tightening feature sometimes works more than my bare hands can handle.

Pete

Offline salt27

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Re: A Machinist Question...
« Reply #5 on: May 11, 2008, 04:06:39 PM »
Sum,
I put my chuck-adapter in the freezer over night before I seated it.
It has not sliped in 20+ years of use. I don't know if that has had any bearing on it or not.
Don

Offline Sumner

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Re: A Machinist Question...
« Reply #6 on: May 11, 2008, 04:38:35 PM »
I keep a couple of strap wrenches handy so I can loosen them after a larger size has been used for heavy drilling. Their self tightening feature sometimes works more than my bare hands can handle.

Pete

Yep I have to use the strap wrench usually on bits larger than 1/2 inch and thanks for the freezer tip Don,

Sum

Offline Dean Los Angeles

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Re: A Machinist Question...
« Reply #7 on: May 12, 2008, 10:16:05 AM »
The brass hammer is a good idea, the Loctite not a good idea.

Tapers hold based on the metal-to-metal contact. It's possible one of the tapers is screwed up. Put some Dykem Hi-Spot blue and see if you have good contact. You may have to lap the tapers. One inch drill or not, it should never spin. And once it does spin it galls the taper.

Don is right. If you heat the collet and put the adapter in the freezer and then seat it home with a brass hammer it isn't going anywhere. But you have to have a good fit or it won't matter.
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Offline ol38y

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Re: A Machinist Question...
« Reply #8 on: May 12, 2008, 10:45:36 AM »
I'm confussed?  :?

Wouldn't you want to heat the adapter and freeze the collet. Kinda like putting a crank in m/c cases.

BTW, anyone wanna buy a freezer? Only has two holes in bottom from drill press legs... :-o

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Offline willieworld

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Re: A Machinist Question...
« Reply #9 on: May 12, 2008, 12:03:12 PM »
when i was 30 my wife bought me a drill press for my birthday -a friend told me when you put the chuck on coat the tapers with salt water but dont ever plan to get it off --that drill press has drilled millions of holes and i turned 63 last january --go figure     wilie buchta
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Offline bearingburner

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Re: A Machinist Question...
« Reply #10 on: May 21, 2008, 07:56:08 PM »
It seams like in a Machinist class I took many years ago the instructor said to put a lathe dog on the drill bit and rest the end on the compound to prevent a large drill from spinning in the tail stock. Worked with tapered shank drills in the tail stock should work with drills in a chuck.

Offline Tom Simon

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Re: A Machinist Question...
« Reply #11 on: April 10, 2009, 05:57:07 PM »
I keep a couple of strap wrenches handy so I can loosen them after a larger size has been used for heavy drilling. Their self tightening feature sometimes works more than my bare hands can handle.

Pete

One of my first jobs at a machine shop that hired me in 1981... beside working on this hybrid car for the owner, was to repair several broken Albriecht brand keyless chucks, that had been fitted to a production lathe. A strap wrench was almost always needed to remove drills.

The issue with using them in a lathe is that they self tighten when the drill grabs. Sounds good, but most machinists will use 'reduced shank' or 'Silver and Demming' 1/2" dia. shank drills in sizes designed to cut up to 1-1/4" diameter holes in the tailstock of a lathe, needing to 'poke as large a hole as you can' is a common lathe job. The problem is large cutting flute have a lot a leverage over a 1/2" shank. Relatively expensive keyless chucks self-destruct as a result. We wound up getting rid of the brokem ones, and replacing the rest with keyed chucks.

Offline 754

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Re: A Machinist Question...
« Reply #12 on: May 23, 2009, 02:47:16 PM »
It is just the machine telling why taper shank & tangs were invented. I stopped using 1 inch reduced shanks in a keyless after I saw how hard they bit in..

 To the OP, the taper probably had a bit of damage from the first episode, and is not seating fully.. is tru tho that the bigger the JT shank going intio the chuck, the more you can expect it to hold.

Offline Anvil*

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Re: A Machinist Question...
« Reply #13 on: May 24, 2009, 03:24:09 AM »
On the mill chuck larger bits directly in the R8 collet if possible. For the mill one inch and above, look into cutters like the Rotabroach (annular cutter) to reduce the energy required. For heavy drilling on a lathe go with the MT taper on the bit (no chuck). Have one large enough so you can switch to your boring bar. Drills are more for roughing out holes on a lathe. IMO