My Precision Mathews PM1340GT Arrival

Great little addition to your lathe! Btw. ReAlly like reading all your write ups on the PM. It is probably one of the few new machines in a class within reach of the average hobbyist that I would consider. All it needs now is 10 years of patina from use by a caring craftsman (you) to knock off the "shine" and crisp edges.

Cheeseking said:

Great little addition to your lathe! Btw. ReAlly like reading all your write ups on the PM. It is probably one of the few new machines in a class within reach of the average hobbyist that I would consider. All it needs now is 10 years of patina from use by a caring craftsman (you) to knock off the "shine" and crisp edges.

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Couldn't agree more. I love the patina look that equipment gets. My last one just had that well used but cared for patina and then I sold it.

Oh well, I will give it all I can to get that look on these machines.:thumbsup:

Good job Mike on the write up. I'm currently in the hunt for a new lathe. It's either gonna be this one or the Grizz 4003G.


I was wondering about the 3 phase connection. The addition of the VFD on your part was because there was no 3 phase available?
If 3 phase was available, is the control box already wired for that input? Had you given any thought to just a 3 phase converter box?


Maybe I should send a note off to Ray C. as well, but I really liked your write up and felt you had a pretty good on hand feeling about
lathe. So thanks for your help.


Dean

Dean said:

I was wondering about the 3 phase connection. The addition of the VFD on your part was because there was no 3 phase available?
If 3 phase was available, is the control box already wired for that input? Had you given any thought to just a 3 phase converter box?

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I would assume that he is like me - there is no 3 phase available for residential use. He may not be completely residential, but real 3 phase power even in town is a super high buck installation and ongoing cost. I bought a mill/drill with a 1HP 3 phase motor because I wanted the advantages of 3 phase and the VFD. Smoother operation, lower current draw, programmable e-stop and controls (instant reverse, etc). I use a 2 HP VFD to drive it. 2HP because it was only about $30 more and I figured extra capacity can't hurt. Next mill might be 2HP 3 phase. The VFD supplies 100% power, no degradation and full torque. You can also tweak the Hz to mess with the motor speed. For instance, you could use it to reduce a lathe lower RPM from 70 to 40 or 50 RPM for threading with just a twist of a knob. I have the E-stop set to stop the motor in .2 seconds, nearly instantly. The downside - such as it is - is that the VFD has to drive the motor directly, it cannot drive the control box. In my mill/drill, I gutted the control box and use twisted pair network wires to run back to the VFD for all controls - FWD/REV, E-Stop, Jog, Start.

A static converter is only good to maybe 50% power, so it would have to be at least double your motor to get what you need. If you had a bunch of 3 phase equipment, a rotary converter would be the next thing up from individual VFDs.

Dean said:

Good job Mike on the write up. I'm currently in the hunt for a new lathe. It's either gonna be this one or the Grizz 4003G.


I was wondering about the 3 phase connection. The addition of the VFD on your part was because there was no 3 phase available?
If 3 phase was available, is the control box already wired for that input? Had you given any thought to just a 3 phase converter box?


Maybe I should send a note off to Ray C. as well, but I really liked your write up and felt you had a pretty good on hand feeling about
lathe. So thanks for your help.


Dean

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Dean, Chris pretty much summed it up in his post above about the VFD. I opted to go 3 PH and VFD for two reasons. First 3 phase at lower speeds covers up some of the "pulsing" that you get with single phase (60 hz). Secondly I wanted to be able to "tweak" the RPM slightly in either direction of whatever speed range I am in through the gearbox. This aids in more of less filling in the gaps between available speeds in the gearbox.

I didn't want to go with a simple phase converter because the VFD is so much more efficient and has other benefits which make it a much more attractive alternative.

On my milling machine I opted to go single phase just because of convenience and I didn't see the immediate benefits of 3 ph and VFD since I was going with the variable speed head anyways.

I don't have any personal experience with the 4003G lathe but the Norton style gearbox which both it and the PM1340GT have is a big advantage in my opinion. Having said that the difference between a mainland Chinese machine vs. a Taiwanese may or may not be as big a deal to you as it was to me. They will both do the same things I was just after outfitting my shop with the best equipment available for allotted budget and the Taiwanese machines are definitely a cut above.

If you have any further questions or specifics pertaining to the PM1340GT I would be happy to answer them the best I can but maybe others with the 4003G can chime in or you could ask more specific questions geared towards that lathe in the Grizzly section and perhaps get a few more responses.

Mike.

I also purchased the 3 phase version of the 1340GT, for the reason it saves you the cost/installation of a new 3 phase motor. Changing the motor to a true vector rated 3 phase motor (such as the Marathon BlackMax/BlueMax series), does afford you full torque down to 0 RPM, and full horsepower rating from ~1750 RPM up to ~3500 RPM for something like the Y526 or Y551 models. So much wider working range, and no low speed cooling limitations, but they are costly and not sure if they would fit.

The wiring for this version lathe is set up for a 3 phase connection, availability from the power company it is not something you would see in a residential setting. So one cannot simply connect a VFD and run the machine without wiring modifications, but one could use an electronic or rotary 3 phase converter. A VFD in a vector mode, gives very smooth power delivery over a broad RPM range, plus the advantages of an electronic brake and to some degree motor feedback operation to the VFD. Conversion of the 3 phase lathe/motor to VFD operation is not complicated, but one needs some basic knowledge of electricity and wiring of VFDs. One should use shielded wiring to the VFD controls and for wiring between the VFD and the 3 phase motor. There are also a number of tweaking (programming) variables with the VFD set-up, some are a bit more complex than others. I have opted for relay controls of the VFD signals, which affords some additional controls of other devices and interlocks for additional safety.
Mark

Dean said:

Good job Mike on the write up. I'm currently in the hunt for a new lathe. It's either gonna be this one or the Grizz 4003G.
Dean

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Mike's PM1340GT is no doubt an incredible machine. I have loved following this thread. Someday when life slows down I'll get by Mike's shop and have a look see in person. I have owned the G4003G for just over a year and it is a great machine for what it is. I also would choose the Norton gearbox over the enclosed one in this class of machine. The larger machines have some great features in their enclosed gearboxes but they are intended for industrial use and carry the price accordingly. If I had the budget for the more expensive PM I would buy it and be happy with my decision. If I only had the budget for the Grizzly I would buy it and still be happy. Its fit and finish is very nice and it is very accurate and capable as well and has been absolutely trouble free. Someday when needed or I have spare money I will look into stepping up to a 3 phase motor with a VFD but in the meantime I can still do quality work. My wood lathe has a 3 phase / VFD setup and it is quite nice.

Good luck on your search,
Dave

Hey guys thanks for the reply's. I probably should have mentioned that I am not electrical/electronic challenged. I am however a beginner when it comes to machining.
The question on the converter box was only because I have a Bridgeport 2J up and running on converter box. Seems to work very well but again I don't do big jobs and mostly aluminum.
I do believe the VFD is the way to go. Many more control possibilities.

Is there a way for this board to notify you of respond to a thread that you had posted in. I gotta tell ya I did not know that I had responds to my questions.
Thanks guys ...Dean

Dean said:

Hey guys thanks for the reply's. I probably should have mentioned that I am not electrical/electronic challenged. I am however a beginner when it comes to machining.
The question on the converter box was only because I have a Bridgeport 2J up and running on converter box. Seems to work very well but again I don't do big jobs and mostly aluminum.
I do believe the VFD is the way to go. Many more control possibilities.

Is there a way for this board to notify you of respond to a thread that you had posted in. I gotta tell ya I did not know that I had responds to my questions.
Thanks guys ...Dean

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I think in your "setting" you can check the box that states subscribe to thread posted in.

Then when you log in click on "settings" in the upper right hand, next to the log out, and it will display the threads that you are subscribed to.

I had wanted to get my tailstock DRO machined and installed but have not had time. Well I already had a mess on the shop floor Saturday after doing another machining job so I thought I would throw together my mounting bracket(s) for the linear scale.

Here is the starting point. A piece of 3.5" 6061-T6 aluminum that was needing to be used.


Once I test fit it on the tailstock I marked where I had to mill the small pocket to accept the end bracket for the linear scale. I also saw cut a slit the ring after I drilled and tapped a 1/4-20 recessed socket head cap screw to tighten onto the tailstock.


Completed.