PM 1340GT max spindle RPM with VFD

The 1340GT is a nice balance between size, weight and quality for what you are looking for. There are smaller high speed lathes, some people will use use these as a backup for very small projects. I used a 5C collet system on my 1340GT and did some very small work and for finishing work would run the lathe at high speed for polishing. Even with carbide tooling I didn't need high turning speed above 1600 RPM. The D1-4 machines will handle smalls and also larger turning projects very well, the fit and finish on these Taiwanese machines are very good at the price point. On the belting, if running a VFD I would use a single fixed belt position, there is no real need to switch the belt positions otherwise. The stock motor works well with a VFD even though it is not inverter rated. A few 1340GT owners have switched the stock motors out for 2Hp TENV inverter/vector motors, I usually run these to 125 Hz using a 2.3-2.5" motor pulley. These motors have an upper maximum frequency limit of around 200 Hz, the vector type motors are designed to only run off of a VFD.

I would go with the 1340GT which has hardened gears vs. the 1236GT. At this price point I do not have any other suggestions for lathes, I would not consider the SB lathe line which I feel is overpriced for what you get. The 1440GT is going to cost another 3K, would give you a bigger working range with the larger spindle bore. All of these lathe should be fine to run to 2000 RPM on a regular basis and intermittent under 2500 RPM.
 
I’ll second what mksj says. I replaced the factory motor with a vector drive unit and VFD electronic controls that mksj produced, and have been very happy with the machine. I did do a lot of customization work on my PM1340 and it’s a terrific small lathe provided you are ok with the Norton style gearbox. Support from Precision Matthews has been excellent.
 
I too do a lot of smaller diameter stuff, including threading. I have a 5c collet chuck for when I'm doing small things in a batch, and I have a ER32 that I can just grab with the big chuck for doing quick jobs.

But I also do enough larger stuff that would be difficult to do on a smaller lathe, so the 1340GT is a decent compromise. I'd love to have a dedicated lathe for the smaller work, but Santa Claus still hasn't delivered my Hardinge HLV-H. :D
 
Davidpbest I’ve seen your setup here and it is impressive.

Wrmiller, that would be my ideal setup as well. This will mostly be used next to my PCNC 1100 for prototyping in my freelance mechanical engineering work and usually efficiency is the deciding factor in whether I can make something cost effectively for clients vs shopping to China shops or protolabs. But time is limited for my fun projects too as most can relate. The shop I most enjoyed working in had a 618 toolroom lathe with collets next to a chucked 13x40 engine lathe, backed up to 2 vertical mills with different workholding setups and being able to spread out on a project without changing chucks and indicating vises all the time is such a huge time saver. Out of the question for my home setup in the forseeable future ;). There it’s more about getting the lost out of the space and this machine definitely seems to be the Goldilocks of the category.
 
I can’t dispute the comparative value of the 1340gt and barring any good fortune on the used market I will buy one this year and love it. But this research project mostly left me feeling the resellers and manufacturers of home shop lathes are a little overdue for some new product development. The norton box is a very elegant solution in my eyes but she’s no spring chicken. The 50 year old Emco designs seem to be the last purpose designed high end home/small RD shop lathe lineup. For example one could take the 1340gt castings with different machining ops and for very minor RD cost present a variant of this lathe with servo driven lead screw with a super simple control for any feed or thread fancied. Same goes for a factory integrated version of mksj’s vfd with prox sense. I don’t see why this couldn’t be under $10k, and there seems to be plenty of enthusiastic home shop folks with comfortable budgets to buy one, I would. When all your customers are doing the exact same modification to your product I would take that as a sign you are missing the mark, and in 2020 you should not need to take to the internet to figure out how to cut a m5x.8 or m12x 1.75 on your brand new lathe. Pro machinists might scoff at the Tormach products but they seem to sell plenty by filling a needs driven niche rather than grinding out scaled down versions of ancient industrial tools. In a culture where people spend god knows what to “build” their flavor of ARs to dump 30 little pieces of lead into a gravel pit wall super quick or kit out their jeeps to go round the ‘burbs why do we need to settle on machine tools?
 
Totally agree with your comments on the lack of value added in these Asian machines. FWIW, there is at least one guy here who's putting the Clough42 electronic lead screw (https://tinyurl.com/w6jlnqf) on a PM1440. I have long commented that on the knee mill side of things, we are well over due for a replacement of the conventional Bridgeport J-head. That head is positively 1890's technology.
 
parshal said:
I, too, have the 1340 with VFD that MKSJ built for me and I flipped the pulleys. I run it with the slowest speed lever and only use the VFD to adjust speed. In the other lever positions it's just way too fast for my work, even in Delrin. I can't keep the feed rate slow enough to keep smooth finish if it's running that fast.
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Do you know if MKSJ is still making VFD setups?
 
MKSJ would love all the business you can throw his way. He is a tremendous resource. Help support the knowledgeable.
 
Thanks for the reply. I am new to this forum. Actually I am new to forums in general. How may I contact MKSJ? By the way, extraordinary work on your 1340GT set up. Very inspiring. Hope I can come even close to something like that.
 
These lathes are limited to around 2000 rpm because the chucks used at that size have a speed limit - usually 2000 rpm.
 
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