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- From: Lawrence London <lfljvenaura@gmail.com>
- To: machinist@lists.ibiblio.org
- Subject: [machinist] Chuck in a chuck
- Date: Sat, 22 Feb 2014 00:10:33 -0500
http://www.practicalmachinist.com/vb/general/chuck-chuck-280648/
Thread: Chuck in a chuck
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Chuck in a chuck
Curious to hear pro's and con's of this practice. I've got a short run of copper nubs to make and pulling my 10" chuck off my A1-6 spindle is like.... meh. I have a nice Bison collet chuck on a A1-6 backplate that I made.... I chucked it up to save time. Which made me want to hear what the salty pretzels in the bag think of this.
What I did:
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02-21-2014, 05:21 PM #3
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02-21-2014, 05:24 PM #4
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02-21-2014, 05:25 PM #5
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People do that all the time. I use a small drill chuck in a chuck for polishing small parts in my wood lathe.
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02-21-2014, 05:39 PM #7
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Only flaw I see is the presence of a 3-Jaw as 'master'.
Were it a 4-Jaw 'master', 3-Jaw or collet 'sub', you'd have far better grip AND the inherent ability to dial-in either low/no TIR, OR a deliberate eccentric if there was a need for a run of such.
JM2CW .. D1-(n) swaps are easy enough here, but that eccentric capability on a plate-mount 5C or ER-series can be handy.
Bill -
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I've done the same as others. Obvious discretion applies. And try when grabbing a chuck with a hollowed out casting on the back (such as many 4-jaws) that you hold over solid material rather than a cored section.
I've also taken my lathe chuck off the spindle with the work still held, then grabbed the chuck in the dividing head chuck, then returned it to the lathe, so that I didn't have to break a setup on finicky, flimsy parts.
Look closely, that 3-jaw is set-tru. He can dial it in if he so chooses.
Originally Posted by thermite
Only flaw I see is the presence of a 3-Jaw as 'master'.
Were it a 4-Jaw 'master', 3-Jaw or collet 'sub', you'd have far better grip AND the inherent ability to dial-in either low/no TIR, OR a deliberate eccentric if there was a need for a run of such.
JM2CW .. D1-(n) swaps are easy enough here, but that eccentric capability on a plate-mount 5C or ER-series can be handy.
Bill -
Nothing wrong with that! Both 3-jaw AND 5C chucks are SETTRU/SETRITE... You can make it as accurate as you want it to be. Just mark them to always be able to position them in the 0-TIR position and you'll have a 100% repeatable accuracy.
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02-21-2014, 05:58 PM #11
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Not by much. And it is still a scroll-back - much less clamping force to-hand than 4-J independents have to offer. Originally Posted by Halcohead
Look closely, that 3-jaw is set-tru. He can dial it in if he so chooses.
That part would bother me more than centering. -
doubts
Maybe you haven't noticed that the 3jaw chuck isn't a cheap one, it's a BISON or a ROEHM as well as the 5c chuck is a BISON. Both could work out fine...
Originally Posted by thermite
Not by much. And it is still a scroll-back - much less clamping force to-hand than 4-J independents have to offer.
That part would bother me more than centering. -
02-21-2014, 06:31 PM #13
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I'm doing it tonight- a little import 3 jaw (gift) in my nice 12" Pratt-Burnerd, going to be doing some little stuff in brass...
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02-21-2014, 06:32 PM #14
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You've worn out that saying.....I're read it 3 times today.... Originally Posted by wgnrr1
Been there, done that, didn't buy the t-shirt.
Josh -
Hey Bill! At least as far as runout, the 10" 3-jaw chuck is a Set-Tru AND that Bison 5c chuck is also set up as a Set-Tru. I did a quick setup and got it running about +\- .001" and called it good. For these parts they could .010" out and it wouldn't matter! Originally Posted by thermite
Only flaw I see is the presence of a 3-Jaw as 'master'.
Were it a 4-Jaw 'master', 3-Jaw or collet 'sub', you'd have far better grip AND the inherent ability to dial-in either low/no TIR, OR a deliberate eccentric if there was a need for a run of such.
JM2CW .. D1-(n) swaps are easy enough here, but that eccentric capability on a plate-mount 5C or ER-series can be handy.
Bill
I hear you about gripping power. At least for the operation I'm doing- on copper no less- it won't matter. I do have a lot of faith in the 10" Bison chuck's grip.
Anyway- your points are good and I'm not arguing them; just making conversation!
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As long as we are talking about it- that Bison 5C chuck is really nice. Made in Poland, which I think is no longer a given with Bison. It wasn't cheap. I made a Set-Tru backplate for it that bolts to my A1-6 spindle with really great repeatability. I need to find more work for it- I have a ton of 5C collets that came with my other lathe; I just don't seen to get much small work.
Although, my Webb spinning at 1800 rpm is a little much <g>. What I REALLY need is a top-shelf toolroom lathe. Anyway. Rambling here. I'm beat. Just finished a $2200 run of parts in 8 days, deburred and marked with part #'s today, packed to survive the Apocolypse and away they will go on the UPS truck shortly. This next thing- the little copper nubs- is for the final touch on a run of beer tap handles I made and has no time pressure. Given that, I should just man up and take that 10" chuck off and mount the 5C chuck properly!
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02-21-2014, 06:50 PM #17
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Then it IS a 'cheap' one. Just not a 'super-cheap' one. Originally Posted by maxmartnl
Maybe you haven't noticed that the 3jaw chuck isn't a cheap one, it's a BISON or a ROEHM as well as the 5c chuck is a BISON. Both could work out fine...
And still a scroll-driven, not power-driven wedge, ramp, or balanced-lever (see $chunk et al).
SCHUNK GmbH & Co. KG Spann- und Greiftechnik
Mind - when it comes to clamping force, virtue amongst scroll-backs - 3-Jaw or other - is akin to virtue amongst hoors.
There ain't a great deal to be found there, and even so - once stressed by temptation and cheater-bar, it don't last long, nor repeat forever.
Anything done with proper respect of its limits CAN work, and for a longish time...but in general, if one has the choice, far better to have the outer chuck working on screws, inner or 'held' one on scroll than the reverse.
Bill -
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BISON-BIAL SET-TRU are not CHEAP and are not inaccurate. I've a KLOPFER WEDGE type, a BURNERD GRIPTRU 6-jaw and a few EMCO and FORTE STEEL(SCA comparative) and BANI and REISHAUER 3 and 4-jaws chucks and have been able to compare a few makes. Modern BISON/BIAL chucks are equal to the top notch other chucks. The design doesn't make the difference, the make does and the Polish seem to be able to stand to their sayings. Don't underestimate these guys...
SCHUNK btw is no better then KLOPFER by my findings, or SMW or KITAGAWA.
Originally Posted by thermite
Then it IS a 'cheap' one. Just not a 'super-cheap' one.
And still a scroll-driven, not power-driven wedge, ramp, or balanced-lever (see $chunk et al).
SCHUNK GmbH & Co. KG Spann- und Greiftechnik
Mind - when it comes to clamping force, virtue amongst scroll-backs - 3-Jaw or other - is akin to virtue amongst hoors.
There ain't a great deal to be found there, and even so - once stressed by temptation and cheater-bar, it don't last long, nor repeat forever.
Anything done with proper respect of its limits CAN work, and for a longish time...but in general, if one has the choice, far better to have the outer chuck working on screws, inner or 'held' one on scroll than the reverse.Bill -
As long as the end result meets your accuracy standards, why not? You won't be able to lean into the cut quite as heavily, though.
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- [machinist] Chuck in a chuck, Lawrence London, 02/22/2014
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