What's new
What's new

Boring small diameters in lathe soft jaws.

ThisIsShopLife

Plastic
Joined
Oct 31, 2017
I have a job coming up where I will need to bore a .375 diameter into my chuck jaws. It is not a production job so investing in a collet chuck is out of the question. Curious if anybody has recommendations on best practices and tooling for this as I have zero experience boring jaws to less than 1.250. Some of my thots have been just drilling them using .375 carbide drill, live milling with small endmill, or miniature boring bars etc.

Lathe has live tooling and Y-axis.

Part tolerances are +/-.005 on OD.

Thanks !
 
What I do is use jaws that come to a point, install them so you have room for a 1/4 bar in the I.D. chucking position. On my Mazak I also do a TPC change so the bar moves away .005 before it moves out. With very small passes I cut to my diameter. I also cut a taper larger to the chuck so I know my material is held at the jaw top, this taper depends on jaw depth. Then I close my jaws adjust my diameters and cut again. Then I move my jaws in one V groove and chuck up my material. Love Louisville if you are near there!
 
Thru or to a shoulder?

Thru - Chuck on a washer or thin pc. of stock stuck way deep in the jaws. Bore big enough to just nick the tips of the jaws.
(It doesn't matter what the actual diameter is, the small bored surface of the jaws will run true and your stock won't know the difference.)
Remove washer and clear out where the washer was sitting to a bigger dia.

To a shoulder - chuck on a smaller-than-.375 drill shank or gage pin., grind up a b-bar out of a small trashed endmill and have at it.
 
Cut relieve to the back side of the jaws and bore as usual with small boring bar to 3xD...5xD depth?
I'd choose PH Horn miniature solid carbide boring bar for the job but that just based on what I have in the drawers..
 
grind up a b-bar out of a small trashed endmill and have at it.

Beat up endmills make the best little boring bars ever.. And they are FAR cheaper than
buying new ones.. And you get the advantage that they are high positive, where as most
of the small stuff you buy off the shelf is neutral.

I've held down to 3/32 in a 10" chuck in soft jaws... Make sure they
are pointy...

And don't forget that jaws can be modified in a vise on a mill if need be...

Also never hurts if you have some way to mount up a small manual 3 jaw or 4 jaw.

I also occasionally will use a straight shank ER16 or an ER32 in bigger jaws...
 
I have a job coming up where I will need to bore a .375 diameter into my chuck jaws. It is not a production job so investing in a collet chuck is out of the question. Curious if anybody has recommendations on best practices and tooling for this as I have zero experience boring jaws to less than 1.250. Some of my thots have been just drilling them using .375 carbide drill, live milling with small endmill, or miniature boring bars etc.

Lathe has live tooling and Y-axis.

Part tolerances are +/-.005 on OD.

Thanks !

Funny when I see the word "small" I think something totally different. :D

OP I know you don;t want to invest in a collet chuck, BUT this here is minimum investment and you will use it and use it and use and use it.;


Standard%20Catalog_0156_0002.jpg
 
Beat up endmills make the best little boring bars ever.. And they are FAR cheaper than
buying new ones.. And you get the advantage that they are high positive, where as most
of the small stuff you buy off the shelf is neutral.

I've held down to 3/32 in a 10" chuck in soft jaws... Make sure they
are pointy...

And don't forget that jaws can be modified in a vise on a mill if need be...

Also never hurts if you have some way to mount up a small manual 3 jaw or 4 jaw.

I also occasionally will use a straight shank ER16 or an ER32 in bigger jaws...


I often use end mill as a boring bar and like you said, often grip a smaller chuck
in the bigger one.
 
I have a job coming up where I will need to bore a .375 diameter into my chuck jaws. It is not a production job so investing in a collet chuck is out of the question. Curious if anybody has recommendations on best practices and tooling for this as I have zero experience boring jaws to less than 1.250. Some of my thots have been just drilling them using .375 carbide drill, live milling with small endmill, or miniature boring bars etc.

Lathe has live tooling and Y-axis.

Part tolerances are +/-.005 on OD.

Thanks !

You can actually leave the chuck and its jaws TF alone, and instead adapt or even "make" a form of spring-collet specifically for the short-run tasking that is actuated BY your chuck.

Worse-case, either mini-chuck or straight-shank mounted collet system just held by your present chuck - NOT directly "cycled" - and operated manually.

Those "solutions" are slower as to cycle time, and by a LOT, usually. Short enough run, that might still be the least-risk and least-cost option?

I'm assuming where "live tooling" exists it is a workhorse of a CNC mount, not a cheap toy, nor a museum-escapee, and that the "chuck" is a good one, and power-operated, so messing with it AT ALL isn't really your fondest wish?

ELSE you would already HAVE a full collet system of one or more flavours for it as a generally useful extension to its ability to earn coin.
 
just throw a straight shank er32 or er40 collet chuck in there and run your parts in that. Thats what we do.
 
Funny when I see the word "small" I think something totally different. :D

OP I know you don;t want to invest in a collet chuck, BUT this here is minimum investment and you will use it and use it and use and use it.;


OT, curious what do you/your shop find 'small'?. :D

I used to cut with 1/16" and think that was small, new job has me using .007", .020" endmills! :eek:
 
OT, curious what do you/your shop find 'small'?. :D

I used to cut with 1/16" and think that was small, new job has me using .007", .020" endmills! :eek:

Yup. Small to me is Tiny to others. Turning on 1mm TGP bar is fairly common. Using those same size Endmills is normal, Drilling .00097" diameter holes, Boring with a .0078 bar.

R
 
OT, curious what do you/your shop find 'small'?. :D

My simplistic (and actual Day Job) world-view?

"Small" a minimum 8X magnification, better-yet 20X and binocular was required, not optional.

"Large" was when you needed a traveling crane to change the tooling or toolpost, not just the workpiece.

In-between was "medium".

If you have to have stairs, a catwalk, or an elevator to get INTO or ONTO the machine, and/or ride ON it's carriage to run it? Or it WAS the building?

That's VERY large.

I did say "simplistic"?
 
Using ER collets did actually cross my mind at one point.

But another issue I'm facing is this job will be a qty. 120 pcs. with 28 different variations of this part on the OD dimension ranging from .375 up to 1.375. Trying to plan the most efficient way to run this job. All parts will be bar fed from 1.5 bar stock.

I was planning on using the sub spindle with soft jaws to pick it off and finish the back side and I would just start with the smallest OD part and bore sub spindle soft jaws to that diameter, run those few parts, bore the soft jaws again for the next diameter I need, run the next few parts, and so on... That way I would only need to use one set of soft jaws for the whole job.


If anybody has other suggestions to run this job more efficiently , I'm all ears.

I guess my thot is I will be boring soft jaws anyway it would maybe make sense to use a small diameter boring bar to start out with for the smallest outer dimensioned part.

Thanks everyone for the input so far!
 
Now that we know what you are doing. Machine the jaws at an angle to the inside, that way you will only have to bore a short distance for small diameters and the length will increase as you bore larger. Look at the inside of a small bore collet to get the idea, my soft 16c collets have quite a taper inside.

Ed
 
If anybody has other suggestions to run this job more efficiently , I'm all ears.
I cannot see it actually being any help to YOU, 'cept MAYBE for "futures" planning, but that's Hardinge "loop" nose-closer 2J or Burnerd Multisize (also nose-lever closer), here.

CNC and POWER operated? Oy! Wouldn't I love to at least TRY Ortlieb's "Quadro". Take note of blade type, steel spring-collet type, and ability to set up for dual-grip as well.

QUADRO(R) Dead Length Collet Chucks

They even have a manual lever-actuated option. Not cheap, I am sure, but really flexible once you have "Jack or better" for openers to get into their game!

If I HAD that? My 5C, 2J, Burnerd Multisize, Rubberflex 9XX, ER-20, ER-40, and TG 100 could ALL be "elsewhere".
 
Using ER collets did actually cross my mind at one point.

But another issue I'm facing is this job will be a qty. 120 pcs. with 28 different variations of this part on the OD dimension ranging from .375 up to 1.375. Trying to plan the most efficient way to run this job. All parts will be bar fed from 1.5 bar stock.

I was planning on using the sub spindle with soft jaws to pick it off and finish the back side and I would just start with the smallest OD part and bore sub spindle soft jaws to that diameter, run those few parts, bore the soft jaws again for the next diameter I need, run the next few parts, and so on... That way I would only need to use one set of soft jaws for the whole job.


If anybody has other suggestions to run this job more efficiently , I'm all ears.

I guess my thot is I will be boring soft jaws anyway it would maybe make sense to use a small diameter boring bar to start out with for the smallest outer dimensioned part.

Thanks everyone for the input so far!

I have a suggestion----cough up some money and invest in yourself. It sounds like you're a tight ass, I might be wrong. But if you're running a Lathe with a sub-spindle you're only kicking your own ass, not buying all the toys that make them efficient.

R
 
Yup. Small to me is Tiny to others. Turning on 1mm TGP bar is fairly common. Using those same size Endmills is normal, Drilling .00097" diameter holes, Boring with a .0078 bar.

R

High speed spindles? Ours are 'standard' 10k which means everything (in that range) runs slooowww. :(
 
I have a suggestion----cough up some money and invest in yourself. It sounds like you're a tight ass, I might be wrong. But if you're running a Lathe with a sub-spindle you're only kicking your own ass, not buying all the toys that make them efficient.

R

I'm not against spending money for a collet system if that is what we need. Here's a scenario tho: The job coming up after this one I will need to grip on a 6" diameter slug. I know next to nothing about collet chucks and their ease/difficulty of installation but the big question is how much time would I burn up switching out from collet chuck to jaw chuck?
 
About as much time as you’ll burn boring jaws for every size OD.
Plus, you’ll have it for future small jobs.

Buy once, cry once.
 








 
Back
Top