Looking to buy a Lathe, help me find the right one

[JustTinkering]

Well Iam looking into getting a lathe, and would like to hear your advice on what you think is the right size and brand.

I'll give you some info on what I am trying to do so you can better help me.

i am looking to bore out some old alum atv cylinders that I have so i can press in new sleeves,"so no need to be 100% perfect" the diameter's range from 3-5 inches and the total cylinder height is from 5-7 inches. the out side of the cylinder is about 8 inches across at the widest point, so not sure what size lathe i would need for that size swing out, more then 8" ? or not? I am new to this so go easy on me. here is a pic of what i am working with



I am not opposed to buying used or new, just looking for a good price being on a hobbyist budget. I am located in MI, if that helps
also if anyone has any good links on reading or video on tools and proses of boring, that would help someone just starting out would be much appreciated.

Thanks for your time

DEREK

[aametalmaster]

I would look for a used 10" american built lathe like South Bend, Logan, Atlas, and a few other goodie brands that i can't find in my head right now. Join my SBL10K lathe group and look at the how to do pictures there. A 9" lathe might do you but a 10" would be better for sure...Bob
http://groups.yahoo.com/group/southbend10k/

[JustTinkering]

Ahh just the man I was hoping would reply, after doing some poking around this morning. I am also joining the 10k group now


thanks

DEREK

[JustTinkering]

ok so now i have a few new questions.

1. lets say the cylinder has a max radius of 9", so i would need a lathe with a minim of 4.5" swing over the bed and carriage?

2. looking at the pic i posted earlier, how would you even get that chucked in a lathe? when boring wouldn't the cylinder have to be balanced? if so, how would you do that with a part that is not symmetrical or balanced?

Thanks

DEREK

[aametalmaster]

Thats why i said a 10" lathe to give you a little more room to make sure the ears on the part don't hit anything. You would clamp that part to a faceplate and center it by the bore until it runs true. If boring all the way thru the part it will have to be held off the faceplate either by a fixture (great if you have lots the same) or a spacer ring of some sort. If not the boring tool will hit the faceplate and won't go completly thru your part...Bob

[aametalmaster]

http://www.youtube.com/watch?v=uFKQrKMNYig

[JustTinkering]

Thank you, That helps a lot, would you happen to know what boring bar set up that is?

also would anyone know of any good sources to start looking for a south bend 10k ?

Thanks

DEREK

[aametalmaster]

Here is a 10K for sale in SE Pa. Don't know where you are at but it looks pretty good...Bob
http://www.practicalmachinist.com/vb...lvania-219277/

[aametalmaster]

Originally Posted by JustTinkering

Thank you, That helps a lot, would you happen to know what boring bar set up that is?

DEREK

It looks just like a regular boring bar that holds carbide inserts and its in a fancy tool post...Bob

[AR1911]

if you can mount it to a faceplate with the head stud holes you can get away with a 10"
If you have to use external clamping bars as in the video above, you might want to go with a 12" or larger

SB or Logan or Sheldon are fine, if you can find a pristine eample. the last of these was made around 1980, so it's 30-year-old machine. Avoid the Craftsman lathes for the most part, although the late 12" undercabinet with 1/2" ways would be worthwhile.

One thing to keep in mind: All the wear in an older lathe is in the first 6" from the chuck, which is exactly where your saddle will be running as your boring bar moves into the cylinder. .001" wear will be mirrored in your bore, no matter what you do. You could conceivalbe back the saddle away to an unworn section of bed and use a long boring bar, but then you give up the rigidity that brings accuracy. so, an unworn, accurate bed is more critical for your need than say, cutting bronze bearings or making spacers.

Don't write off the asian lathes. I have a couple of Encos made in Taiwan ca 1985, both are fine machines with separate feedshaft for the apron, which few American lathes have. Even a new 12x36 or larger is likely as good as 95% of the old iron out there.
Right now I have a very nice 9" Southbend in excellent condition. But I do almost all my projects on the 10" Enco behind it. It's just as accurate and a lot more rigid.
Bottom line is most any 10" or larger lathe will work for you.