Turret for a benchtop lathe

[durableoreo]

Wondering how common CNC turrets are for small lathes. Couldn't find much on eBay or Alibaba. Are small turrets so rare? Something like this:

The backstory is that I'm doing a CNC conversion of a 9x20 lathe. For years, I was in need of a DRO and variable speed. I realize that being unwilling to change belts to adjust spindle speed is a character defect but apparently my character has taken a bit of a "set". I also acknowledge that a few speeds should be enough but I've watched a lot of 10EE content and became convinced that the variable speed is a real advantage for odd materials that only behave with particular feeds and speeds. Eventually I found some videos about electronic lead screws (ELS) would give me most DRO functions and I could throw away the change gears, too. From there, you're basically doing all the work of a CNC retrofit so I threw myself in the deep end and and purchased a Masso Touch control, closed-loop stepper motors, and an AC servo (86M-DHT from DMM and DYN4 driver) for the spindle. That should get me variable speed, ramp up, ramp down, and indexing.

The whole setup will enable me to cut tapers with a fixed tool post and thread quickly. Why quickly? Well, the other day I had to cut an external 5/8-18 thread in a O-1 part. Hadn't done any threading in 6 months so I was a little rusty. All told, it took 2 hours and I made a mistake on the 25th pass (too deep of a cut, IIRC) which forced me to make the part again and cut the threads again. The 2nd attempt was faster, of course, but the result was not the best because O-1 doesn't cut perfectly at 8 SFM and it still took an hour. Seems impossibly incompetent to take so long. So I'm hoping that CNC will speed me up a bit.

So... turrets for small lathes... where to buy?

 

[mmcmdl]

25 passes on a 18 pitch thread ? No wonder it took 2 hours . As far as vertical turrets on a manual , I've never seen one that would retrofit easily . If you check out most Hardinges , they are horizontal . My question would be , why did you have the need to make 25 passes threading ? The tool needs to cut and not rub .

 

[pacifica]

Wondering how common CNC turrets are for small lathes. Couldn't find much on eBay or Alibaba. Are small turrets so rare? Something like this:

The backstory is that I'm doing a CNC conversion of a 9x20 lathe. For years, I was in need of a DRO and variable speed. I realize that being unwilling to change belts to adjust spindle speed is a character defect but apparently my character has taken a bit of a "set". I also acknowledge that a few speeds should be enough but I've watched a lot of 10EE content and became convinced that the variable speed is a real advantage for odd materials that only behave with particular feeds and speeds. Eventually I found some videos about electronic lead screws (ELS) would give me most DRO functions and I could throw away the change gears, too. From there, you're basically doing all the work of a CNC retrofit so I threw myself in the deep end and and purchased a Masso Touch control, closed-loop stepper motors, and an AC servo (86M-DHT from DMM and DYN4 driver) for the spindle. That should get me variable speed, ramp up, ramp down, and indexing.

The whole setup will enable me to cut tapers with a fixed tool post and thread quickly. Why quickly? Well, the other day I had to cut an external 5/8-18 thread in a O-1 part. Hadn't done any threading in 6 months so I was a little rusty. All told, it took 2 hours and I made a mistake on the 25th pass (too deep of a cut, IIRC) which forced me to make the part again and cut the threads again. The 2nd attempt was faster, of course, but the result was not the best because O-1 doesn't cut perfectly at 8 SFM and it still took an hour. Seems impossibly incompetent to take so long. So I'm hoping that CNC will speed me up a bit.

So... turrets for small lathes... where to buy?

Get a used geometric die head; I see one on ebay right now, 5/16d with about 10 chasers for 349.99. Will cut perfect threads in one pass and you can easily adjust the head from class 1 to class 4 threads , about 15 to 20 sfm on stainless, 16 to 24 tpi.

 

[mmcmdl]

Get a used geometric die head; I see one on ebay right now, 5/16d with about 10 chasers for 349.99.

That's the way to go .

 

[benmychree]

Yes, die heads are a wonderful thing to have and use, there are several other makes besides Geometric, but Geometric is the easiest to set upn and chaser sets are readily available both used and new, that said, a die head is not something practical if one is making a one off part, unless it is already set up with the chasers needed. I have a 9/16 Geometric die and a Jones & Lampson Hartness die in 7/8 size. I used the Geometric die recently to thread a couple of 7/16 studs, had a quite bad time getting it to work satisfactorily, I think Covid19 had it jammed up ---

 

[woodchucker]

I think Covid19 had it jammed up ---

probably.. it just wasn't up to the task yet.

 

[durableoreo]

25 passes on a 18 pitch thread ? No wonder it took 2 hours . As far as vertical turrets on a manual , I've never seen one that would retrofit easily . If you check out most Hardinges , they are horizontal . My question would be , why did you have the need to make 25 passes threading ? The tool needs to cut and not rub .

I've seen people cut small threads (M10) in brass at 1500-3000 RPM on a CNC lathe in 10 passes with a polished aluminum full-profile insert. That would be about 0.024" deep , so about 0.0024 per cut. In my case, it was about 0.028" deep but using medium hard O-1 at very low surface footage. The tool was made in the shop, single-point, solid carbide, with slightly positive geometry. First few cuts are 0.005 but a bunch of cuts are 0.001 and several spring passes. The cut sounded fine and chips were curling off the tool. Blondihacks and others have pointed out that a bunch of passes are needed on hobby equipment. How many passes would you take? What lathe?

 

[benmychree]

probably.. it just wasn't up to the task yet.

Actually, I had not used it since before Covid, and I think it got gunked up with TapMagic, which seems to solidify into a black gooey cruddy mess, combined with shop dirt and whatever the wind brings along.

 

[projectnut]

One of the used equipment dealers I frequent literally has a hundred or more die heads and thousands of sets of chasers. I've always avoided them because I rarely make more than a few of the same size threaded fasteners at one time, and they seem to be overkill for anything short of production work. You might want to check used equipment dealers in your area. Around here most dealers are asking a fraction of the prices listed on eBay.

As for infinitely variable spindle speed that was something I was looking for when I purchased a lathe a few years ago. I ended up with a Sheldon MW-56-P. It uses a Worthington All Speed Drive to vary spindle speed. The All-Speed drive is similar to a Reeves drive. In this case sheaves are opened and closed by a gear motor controlled by a push button on the operator console. Speed range in high range is 360 to 2200 rpm. Low range goes down to 60 rpm.

Here are a few pictures of the machine. Note the tach speed is at 599 in one picture and moved up to only 601 in the next one. The other pictures are the Worthington drive in the cabinet below the headstock.

 

[benmychree]

Does it make much noise?