Cut off cycle time

[HuFlungDung]

Vern,
You do lose some spindle bore capacity with the drawtube. For 2.5" stock, it might be tight even with the TL2's 3" spindle bore. Mind, a collet chuck big enough for 2.5" stock would likely be pricey to tool up.

Maybe an SMW air chuck for $87000 would be in order? They don't take away from the spindle bore.

Edit: No, no, what was I thinking. The 12" SMW is $87,000. You'd probably only need an 8

[Geof]

Hu's $87k is a bit rich for my taste, and I think he has transposed the numbers because my memory recalls him posting something about $78k in a different thread a while back.

However, there is an alternative, allow me to link you to one of my threads:

http://www.cnczone.com/forums/showthread.php?t=19212

Somewhat less costly than Hu's approach; the chuck if I recall correctly was less than $6000, the hydraulic unit was about $5000 and we had the adapters and drawtube done by a local job shop for (I think) $1500 to give a total of $12,500. Of course the GT20 was bought with the 8" hydraulic chuck option at an added $8000 so in effect the total cost was $25,000. But it gave us a machine that can part off 2-3/4" round bar and the alternative was a SL20 Big Bore at a heck of a lot more.

Incidentally it was tight getting 2.77" inside the drawtube when the OD had to be kept below 2.997" (which is the actual bore of the GT20 (and TL2) spindle, but we did it.

[Delw]

Originally Posted by Geof A 0.125" tool is a bit thin for 2.5" diameter but you do have a hole so maybe it will be okay; a narrow tool is more prone to the shimmy I mentioned. Parallel to +/-0.003"? Yes, probably but not necessarily smooth. Have a look at the pictures in post #17 in this thread discussing parting aluminum. http://www.cnczone.com/forums/showthread.php?t=48859

Geof this post reminded me I owe you a picture. Happen to have the parts laying in the back.

the big one is 1.995 dia 1 operation( plus hand mill operation) than a few crazy 8's on some sand paper to take the tit off , the part is .032 thickness everywhere +-.002 if I remember correctly and .001 flatness on back side the oal was .417

the small part is 1.595 same tolorance easier for the small part, the job was in 500 quanities every couple months, we just loaded bar up and hit the button.

all tools were iscar and I wanna say the part off tool was .1875, I think I ran 2 iscar part off tools for the 2" one, one tool had a very sharp special ground insert for us from iscar.
you can see in the center of the big part both front and back side were we had the worse problem with chip build up and the part just being too thin.

I would love to have this Job again, I don't remember exact cycle tmes but we ran balls out fast on it.

we would loose maybe 2 parts per 25-30 due to them trying to be flying saucers inside the machine

Delw