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-   -   Machinists, need your input... (http://www.mcarterbrown.com/forums/ask-experts/230740-machinists-need-your-input.html)

PistolRogue 04-06-2013 02:01 PM

Machinists, need your input...
 
I have access to a lathe at work, but the chuck only goes down to about 5/8" diameter. I don't use it a lot, and don't know much more other than basic facing/cutting, and how to avoid crashing the thing.

I have a couple of small parts I'd like to run on it (mostly 1/2" brass rod stock getting center drilled and cut down to 1/4" diameter for a small section. Since the part's final ID doesn't need to be bigger than 1/2", I'd rather use 1/2" stock than cutting down 3/4" that will actually fit the chuck of the lathe.

I'm not looking to buy expensive equipment for the lathe I don't own, and frankly I can't predict how much it would get used anyway, so can I just chuck this up in the existing chuck and use it safely/reliably?

1 32 1 2" Geared Drill Chuck with 3 4 SS Arbor Shank and Key | eBay

Or is there a better way that won't break the bank or require me to perform operations I'm really not qualified for?

Now I'm starting to wonder how much of a dumbass I'm going to sound like for asking this.... :ROTFL:

wes 04-06-2013 06:47 PM

The chuck you linked is really meant for holding a drills not for chucking stock for turning, but for a little small diameter turning you may be OK.

A simpler way would be make a bushing, take a piece of stock that will fit in the existing chuck(5/8-3/4) and make a hole in it the size of your stock, cut some slits in it so it will flex, and chuck in the lathe. You would need a bushing for each diameter of stock you plan to use.

Is there a 5C collet chuck and collets for that lathe, that would be best.

BigOldSkool 04-06-2013 06:49 PM

Get 5/8th stock?

Hawkeye20 04-06-2013 06:56 PM

Quote:

Originally Posted by PistolRogue (Post 2676552)
so can I just chuck this up in the existing chuck and use it safely/reliably?

1 32 1 2" Geared Drill Chuck with 3 4 SS Arbor Shank and Key | eBay

Honestly, all I can think of is images of your work piece or the drill chuck itself working loose and FLYING out of the lathe and impaling someone. The spinning motion, combined with the pressure of the cutting tool makes me think there would be a possibility that the drill chuck could slowly begin to open. Drill chucks are most likely built for straight-on (for lack of a better term) pressure, not pressure that pushes at a sideways angle.

It's hard to say. I would try seeing how it works at a LOW speed (like, below a steel turning speed) and later on then turn it up for the brass/aluminum/delrin or whatever you're working with.

PistolRogue 04-06-2013 07:15 PM

Quote:

Originally Posted by BigOldSkool (Post 2676713)
Get 5/8th stock?

The problem with that is the parts I'm making need a different diameter hole drilled in each side, one side gets a hole for a 1/4-28 thread, the other a 1/8 NPT thread. So at some point it needs to be flipped and the final product is short, just an inch to inch and a half. Final diameter has to be 1/2" max or it won't fit where it's intended to be installed. I could conceivably just leave a 1" portion of it that I leave in 5/8 and hacksaw it off at the end but I feel like with the particular lathe in question it'll be harder to get it chucked up straight with that short of a piece actually making contact with the chuck, if that makes any sense. Would also waste a lot of material that way. Material that's already more expensive then the same length 1/2" stock.

And yes, this will be getting turned at lower speed, I have no reason or desire to be turning this at 3200 RPM or anything stupid like that. I'm an amateur, not an idiot.

Hawkeye20 04-06-2013 07:19 PM

Quote:

Originally Posted by PistolRogue (Post 2676739)
And yes, this will be getting turned at lower speed, I have no reason or desire to be turning this at 3200 RPM or anything stupid like that. I'm an amateur, not an idiot.

When I said slow, I meant closer to ~600 RPM (good speed for cold folded steel) to start with. Do some testing.


Another thing you could do: Ask whoever is in charge of the lathe (or just your boss) if there is a smaller chuck that will go smaller than 5/8ths somewhere in the back storage room? The shop that I work in typically has more than one size of just about anything you could possibly need.

You never know, wouldn't hurt to ask.

dukie 04-06-2013 07:31 PM

Quote:

Originally Posted by PistolRogue (Post 2676739)
The problem with that is the parts I'm making need a different diameter hole drilled in each side, one side gets a hole for a 1/4-28 thread, the other a 1/8 NPT thread. So at some point it needs to be flipped and the final product is short, just an inch to inch and a half. Final diameter has to be 1/2" max or it won't fit where it's intended to be installed. I could conceivably just leave a 1" portion of it that I leave in 5/8 and hacksaw it off at the end but I feel like with the particular lathe in question it'll be harder to get it chucked up straight with that short of a piece actually making contact with the chuck, if that makes any sense. Would also waste a lot of material that way. Material that's already more expensive then the same length 1/2" stock.

And yes, this will be getting turned at lower speed, I have no reason or desire to be turning this at 3200 RPM or anything stupid like that. I'm an amateur, not an idiot.

Are you Sure of that number?? I think you better check that again or you will have some very unhappy customers lol. Unless you are making something other than what I am thinking of.

I would just make a bushing. do all the turning and external threading first, part it off. Flip it, face it, through drill for porting and then drill the npt port. the npt port may not be perfectkly in line with the body but its pipe thread, it really wont make a huge difference. Try and find an npt fitting that actually goes in perfectly straight. the ones from china don't lol.

tony montana 2 04-06-2013 10:47 PM

do you have access to ER32 collets? If you do this would work New C1" ER32 100L Straight Milling Chuck Holder US | eBay

Hawkeye20 04-06-2013 11:15 PM

Quote:

Originally Posted by tony montana 2 (Post 2676884)
do you have access to ER32 collets? If you do this would work New C1" ER32 100L Straight Milling Chuck Holder US | eBay

Well, that's cool.

ER32 collets are interesting. I've only used R8's and 5C's.

tony montana 2 04-06-2013 11:21 PM

I have a ER32 to MT3 for my lathe works great


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