[LongRat]

Based on the time it is taking to cut such a small amount of material, it could well be that you are feeding way too slowly. Speeding that up might well get rid of all of the screech and chatter. Also, you don't mention what tooling you are using.
Normally I would have suggested flex in the tool post on a 9x20 lathe as that is a crippling weak link on the machine as I am sure you know, however you have clearly upgraded that weakness very nicely already. Impressive sheet metal work too.

[BobWarfield]

Jake, I don't know what you mean by an "arm and a leg" (i.e. what your price range is), but spindles are expensive. You can fairly commonly find 5C collet spindles on eBay from firms like Dunham. They'll be circa $700-900, but should be very nice spindles with sealed precision bearings and so on. If that's too much, you will probably have to look at making your own spindle.

I have toyed with that idea, even the idea of making one based on bronze sleeve bearings, which would be a lot easier machining job. In the end, I bought a Dunham spindle, which I intend to use for a 4th axis project.

Best,

BW

[jakemestre]

Jake, I don't know what you mean by an "arm and a leg" (i.e. what your price range is), but spindles are expensive. You can fairly commonly find 5C collet spindles on eBay from firms like Dunham. They'll be circa $700-900, but should be very nice spindles with sealed precision bearings and so on. If that's too much, you will probably have to look at making your own spindle.

I have toyed with that idea, even the idea of making one based on bronze sleeve bearings, which would be a lot easier machining job. In the end, I bought a Dunham spindle, which I intend to use for a 4th axis project.

Best,

BW

Bob,
Thank you very much for the help. I think I might be able to buy a Grizzly 12x24 spare part spindle for about $600. I'll have to figure that one out, there's no detailed drawing, and it just falls into the arm and leg category. I'll keep an eye on ebay and check in with the local tool distributor to see if there's an old 13 or14-40 lathe for super cheep.

Great looking machine, good job!

You didn't mention the spindle speed or SFM...too fast perhaps? Can't imagine how a .02 mm (or inch) diameter cut could cause any problems whatsoever in 1018 unless it's WAY too fast?

Also what does "the height on all tools is positive with perfect center alignment" mean. Perfect center alignment I understand but positive height?

I have a converted Denford ORAC which is similar to yours in size & construction (except mine has 3/4 hp DC spindle motor) and it'll peel off a decent sized hunk of swarf without a whimper. It's a work in progress and I haven't worked it hard yet. So far the biggest loads I've thrown at it were .060" (dia.) roughing cuts in 3/4" dia. 1018 without a problem.

Thanks for the compliment,
I posted a quickreply before I noticed new posts. I meant positive rake on the tool. Not positive height. You know I might just try replacing the bolts for the headstock with stainless bolts. That might help a lot.

[DICKEYBIRD]

Great looking machine, good job!

You didn't mention the spindle speed or SFM...too fast perhaps? Can't imagine how a .02 mm (or inch) diameter cut could cause any problems whatsoever in 1018 unless it's WAY too fast?

Also what does "the height on all tools is positive with perfect center alignment" mean. Perfect center alignment I understand but positive height?

I have a converted Denford ORAC which is similar to yours in size & construction (except mine has 3/4 hp DC spindle motor) and it'll peel off a decent sized hunk of swarf without a whimper. It's a work in progress and I haven't worked it hard yet. So far the biggest loads I've thrown at it were .060" (dia.) roughing cuts in 3/4" dia. 1018 without a problem.

[jakemestre]

Based on the time it is taking to cut such a small amount of material, it could well be that you are feeding way too slowly. Speeding that up might well get rid of all of the screech and chatter. Also, you don't mention what tooling you are using.
Normally I would have suggested flex in the tool post on a 9x20 lathe as that is a crippling weak link on the machine as I am sure you know, however you have clearly upgraded that weakness very nicely already. Impressive sheet metal work too.

Thanks for the suggestion LongRat. I did forget to mention the tooling. I'm using a Sandvik CCMT3251 PF 4215 grade insert. It's in a 1/2" holder that's choked all the way up in the toolpost. I started with the recommended feeds and speeds off the box at .014" radial depth of cut, .004"/rev and 1500SFM. My machine about exploded with chatter with these values so I took it down to the absolute minimum of .004"DOC, .002"/rev and 1500SFM. Still lots of chatter. The spindle is moving relative to the cross slide, but I tightened every bolt and even built some L brackets to help stabilize the headstock.
The only way I can stop the chatter is at 200SFM, .01"DOC and .oo2"/rev. The part takes 26min at that speed, and I need to make it in 3. The insert is rated to 1950SFM(15500RPM at .472"diameter), .079" radial depth of cut, and .009"/rev. The insert will get me there even for a finishing mid grade insert, it's the machine that won't.