Holding in hard jaws and stick out.

plutoniumsalmon · Jan 10, 2019

Hello.
I have this part to do in astm 572 50 steel. I have to mill out a bunch of stuff and threamill some threads. I need to turn it down a bit an face it. Is the material indicated in yellow enough to hold on to for all of this. I am thinking of using hard jaws as making soft ones is not justified for the number of parts.

Will this work? Thank you.

Generic Default · Jan 10, 2019

Definitely not, unless you take a bunch of very light cuts and do it slowly. A collet might work for that but 3 hard jaws will deform the grip contact points at best, and most likely the part will get kicked out of the chuck by cutting forces.

If you were doing that on a live tooled lathe or mill turn machine, you could do the whole thing at once and part off the back side.

litlerob1 · Jan 10, 2019

plutoniumsalmon said:
I am thinking of using hard jaws as making soft ones is not justified for the number of parts.

We're on opposite ends of the justification spectrum for "when to use soft jaws". I think their whole reason for being is 1 or 5 parts.

But I agree, that's not enough to hang onto. I'd build an Aluninium split sleeve and Chuck the shit out of that part. Mill toward the Chuck.

R

Booze Daily · Jan 10, 2019

You could leave the 1.480 dia big and about 2” longer to chuck on and finish it after.

plutoniumsalmon · Jan 10, 2019

Generic Default said:
Definitely not, unless you take a bunch of very light cuts and do it slowly. A collet might work for that but 3 hard jaws will deform the grip contact points at best, and most likely the part will get kicked out of the chuck by cutting forces.

If you were doing that on a live tooled lathe or mill turn machine, you could do the whole thing at once and part off the back side.

Hello.

I am doing it on a live tooled lathe. Can you please clarify what part off the back? My plan was to turn the yellow feature and then flip and use it to hold. Ideally I wanted to mill away the material but there is a part that exceeds my bore capacity and I would not know how to hold it.

plutoniumsalmon · Jan 10, 2019

Booze Daily said:
You could leave the 1.480 dia big and about 2” longer to chuck on and finish it after.

Oh. Good. Client does not care how long that is. It goes into a pipe.

Bobw · Jan 10, 2019

Double them up...

I'm assuming 2" stock, and assuming you can get 2" into your spindle bore..

Cut 'em 13" or so. Do your complicated end, flip, do it to the other end..
Cut 'em in half and finish the small end. Done.

There is a part I do on occasion that gets roughed, sent back to the customer
for heat treat and then back to me for finish.. The only realistic way to do
this part is to double it up, and they get all freaked out when I send in 12 parts
for heat treat and the contract is for 20... Screws their paperwork all up.

plutoniumsalmon · Jan 10, 2019

Bobw said:
Double them up...

I'm assuming 2" stock, and assuming you can get 2" into your spindle bore..

Cut 'em 13" or so. Do your complicated end, flip, do it to the other end..
Cut 'em in half and finish the small end. Done.

There is a part I do on occasion that gets roughed, sent back to the customer
for heat treat and then back to me for finish.. The only realistic way to do
this part is to double it up, and they get all freaked out when I send in 12 parts
for heat treat and the contract is for 20... Screws their paperwork all up.

Hello.
That will fit in the bore (my limit is slightly under 4. But they also have a 4 inch dia part. I like the doubling up idea at the very least for its novelty to me.

Thank you

litlerob1 · Jan 10, 2019

plutoniumsalmon said:
Hello.

I am doing it on a live tooled lathe. Can you please clarify what part off the back? My plan was to turn the yellow feature and then flip and use it to hold. Ideally I wanted to mill away the material but there is a part that exceeds my bore capacity and I would not know how to hold it.

Do the whole part, 5.119" dimension away from the Chuck. Do the Mill work. Come back in with a Groove Tool and do the smaller diameter, close to the Chuck, then part it off with the same Tool.

R

plutoniumsalmon · Jan 10, 2019

litlerob1 said:
Do the whole part, 5.119" dimension away from the Chuck. Do the Mill work. Come back in with a Groove Tool and do the smaller diameter, close to the Chuck, then part it off with the same Tool.

R

Yes. Thats what I was thinking of in the car on the way home. Instead had to think of a back asswards way. The whole part is 6 I am assuming 3x dia stick out is ok?

litlerob1 · Jan 10, 2019

plutoniumsalmon said:
Yes. Thats what I was thinking of in the car on the way home. Instead had to think of a back asswards way. The whole part is 6 I am assuming 3x dia stick out is ok?

4-1 Steel overhang is okay.

plutoniumsalmon · Jan 11, 2019

Final question.

When I part this thing off should I go all the way or leave a bit and cut it manually?
Thank you.

litlerob1 · Jan 11, 2019

I'll often go down not far enough that it wobbles off center, but far enough that I can hit it with a dead blow to knock it off.

R

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