Lathe Comparison - Best small lathe for CNC

[acondit]

I currently have a HF12x36 (33274) and a Grizzly 9x20 (G4000). I am reluctant to CNC the HF because of all the gear drive mechanisms involved. I am thinking about some of the same issues with regard to the Grizzly 9x20 the half gearbox. Additionally, since I may have to begin downsizing my shop I am thinking about selling both of the lathes that I currently own and replacing them with a smaller CNC lathe or possibly two.

It seems silly to buy an expensive lathe with a lot of features (like a gearbox) to CNC. So I am thinking about one or possibly two of the following lathes:

(1) Grizzly 7x12 (G8688)
(2) Microlux 7x14 (82710)
(3) HarborFreight 8x12 (44859)
(4) LatheMaster 8x14 (CQ6120x320)
(5) LatheMaster 9x30 (HD250x750)

Questions:

Other than the obvious concerns of weight, mass and price, which of numbers 1,2,3 and 4 would you choose and why?
Has anyone had the opportunity to do a firsthand physical comparison of both the HF8x12 and the LM8x14? What are the differences between them other than accessories?
If I bought #5 I believe that it would probably be in addition to one of the first four, so, would you keep one lathe manual and CNC one or would you CNC both?

Thanks,
Alan

[RotarySMP]

Given that space is not a premium concern to you, I would not (again) CNC a 7x lathe.

Since you already have the 9x20 and they are cheap, just CNC that. The gearbox which you will put ina box in the corner of the garage is probably only worth about 80 Rinimbi.

Why sell the 12X lathe? You can never have a big enough lathe!

[acondit]

Mark,

We are looking at retirement and moving into a smaller place where space will be at a premium. Also we are looking at moving to a different city and the cost and hassle of moving a 1000 pound lathe is not cheap.

Alan

[Chris D]

I am currently gathering parts for a 9 x 20 conversion to CNC. Your right about the gear train on the 9 x 20's - the questions stands "Could it be made any worse?"

However, through the CNC conversion, just about everything will be gone from my machine. The bed, carriage, cross slide, headstock, and tail stock will be kept, the rest will be made into a boat anchor.

I already have mine converted to a DC spindle drive. I will be using Gecko 320s, Servos, and ball screws for motion. So, as you can see, not much left of the original machine.

Chris

[RTP_Burnsville]

What about a model similar to the Grizzly G0516? It is the model I have been thinking about as a first lathe.

Robert

[acondit]

Robert,

Positives:
I like some of the specs on it (9.75 swing, 21" between centers on the lathe). It comes with 5" 3-jaw and 4-jaw chucks).

Negatives:
I have not heard many positive things about 3 in 1 machines in general.
It seems to have the same poor design on the compound mount as the 9x20.
The mill at the back seems to make that addition of a DRO more difficult.
The fixed position of the mill head in relation to the lathe head makes it less useful as a 4-axis machine.
The size of the milling table attachment to the crossfeed is pretty small even in relation to the minimill.

Plus I already have a RF30 Mill-Drill and a HF Minimill (both R8).

Alan

Originally Posted by RTP_Burnsville What about a model similar to the Grizzly G0516? It is the model I have been thinking about as a first lathe. Robert

[RTP_Burnsville]

Originally Posted by acondit Robert, Positives: I like some of the specs on it (9.75 swing, 21" between centers on the lathe). It comes with 5" 3-jaw and 4-jaw chucks). Negatives: I have not heard many positive things about 3 in 1 machines in general. It seems to have the same poor design on the compound mount as the 9x20. The mill at the back seems to make that addition of a DRO more difficult. The fixed position of the mill head in relation to the lathe head makes it less useful as a 4-axis machine. The size of the milling table attachment to the crossfeed is pretty small even in relation to the minimill. Plus I already have a RF30 Mill-Drill and a HF Minimill (both R8). Alan

Thanks for the response... A couple additional comments.

The mill head does not need to be attached and LMS sells a matching base/table to turn it into a X2 mill ($200).

LMS also has a replacement spindle if one would rather have R8 tooling ($50).

There are a few other places (PennTool) that offer a similar lathe without the mill head but the price is close to the same. Being you have a mill I see your point.

The larger swing and the extra chucks are a nice feature though.

[RotarySMP]

I have been looking at that G0516 also. The leadscrew cover is one less thing to make that you really need on a CNC. Can you get a T-slotted cross slide for it? Get a three phase motor and a VFD and it would be sweet. Still not worth trading in the machines you have though.

[acondit]

Chris,

I have never been totally happy with the 9x20 in terms of quality of cut. (But until recently I hadn't been happy with my 12x36 or my mill. I spent some time tuning both of them and am now getting great finish cuts.)

So, maybe I need to spend some time tuning the 9x20 and see if I can improve the quality of its cuts and get rid of the chatter.

Alan

Originally Posted by Chris D I am currently gathering parts for a 9 x 20 conversion to CNC. Your right about the gear train on the 9 x 20's - the questions stands "Could it be made any worse?" However, through the CNC conversion, just about everything will be gone from my machine. The bed, carriage, cross slide, headstock, and tail stock will be kept, the rest will be made into a boat anchor. I already have mine converted to a DC spindle drive. I will be using Gecko 320s, Servos, and ball screws for motion. So, as you can see, not much left of the original machine. Chris

[acondit]

Mark,

Originally Posted by RotarySMP I would not (again) CNC a 7x lathe.

I know that space was a big consideration for you in deciding upon a 7x lathe. However, within its size limitations, how do you feel about the performance of the cnc'd 7x lathe?

If the 7x lathe had a more powerful motor, would that solve a number of the issues? If so, would it be feasible to increase the power of a 7x lathe with a treadmill motor to increase its cutting power?

Would the 8x14 be enough larger to satisfy 90% of the reasons behind your statement about not CNC'ing a 7x again?

I know the feeling that "one can never have a big enough lathe", but I have done jobs that were actually less scary on a smaller lathe (turning very small parts up next to a big chuck).

Thanks,
Alan

[phantomcow2]

I would keep the 9x20.
but for the record, the 7x12 I have is a great little lathe. I have been able to keep my work within .0005" if I pay attention to accuracy. Most of the stuff i do is not critical with measurements, so i dont bother with that. The motor on my Homier is labeled as 400w and 4/5HP. I can stop it with my hand at the lowest possible speed which i think is 30-40RPM. After 50 or so torque jumps up

[acondit]

Phantomcow2,

Two of the three people suggesting that I keep the 9x20 don't have one. I think the idea of the 9x20 may actually be more appealing than the fact of the machine.

I had basically considered and rejected the 9x20 as the CNC option for a variety of reasons. Most of the things I do are up close to the chuck; the 4-jaw that came with the G4000 is not something that I want to deal with for a CNC machine; the crossfeed support needs to be modified to even think about CNC; and I can probably sell the 9x20 configured as it is for almost enough to buy one of the smaller machines.

If I need a machine longer than 14", I may well need the 9x30. Most of the things that I have turned, that would have been too long for an 8x14, were too long for a 9x20 (hence the 12x36). There is no way that I can justify having both a 9x20 and a 9x30.

I have only seen one 9x20 configured for CNC and that in and of itself may say something (I am not sure what?).

I may reconsider keeping the 9x20, but what I want to find out if any of the other smaller options that I listed present a better option than the 9x20.

Alan

Originally Posted by phantomcow2 I would keep the 9x20. but for the record, the 7x12 I have is a great little lathe. I have been able to keep my work within .0005" if I pay attention to accuracy. Most of the stuff i do is not critical with measurements, so i dont bother with that. The motor on my Homier is labeled as 400w and 4/5HP. I can stop it with my hand at the lowest possible speed which i think is 30-40RPM. After 50 or so torque jumps up