Mill Choice PM-728VT or PM-833VT

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RJS100
Posts: 25
Joined: Tue Oct 20, 2020 8:41 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: none

Mill Choice PM-728VT or PM-833VT

Post by RJS100 »

Hello,

I am 99% done building the electronics for a CNC mill conversion using the Acorn board and closed loop steppers. My goal for the mill is to make one-off prototypes mostly with aluminum and some other harder metals. Since I don't know exactly what I will be making, I could actually end up working with the harder metals rather than aluminum. The last time I worked a mill was in high school using a Bridgeport so I have absolutely no experience with smaller benchtop machines. I had originally planned on converting the PM-728VT, but have since seen lots of videos that stress the importance of rigidity. I am now considering the PM-833VT which is about twice as heavy. I have listed the key features of each below. While the PM-833TV has a bit greater travel than the PM-728VT, I most likely will not need the additional travel or slight larger table size.

It is now time for me to pick the mill to convert. I welcome any of your thoughts to help me understand what I would gain from the added heft of the PM-833TV or any other thoughts comparing the mills.

Thanks... Richard

PM-727VT
Weight: 375 lbs.
Motor: 1HP BLDC
Drive: 2 speed belt drive
Bearings: Angular contact
Lube: 1-shot
Max Spindle Speed: 4300
Made: Taiwan


PM-833TV
Weight: 750 lbs.
Motor: 2HP + VFD
Drive: 1 speed belt drive
Bearings: Tapered Roller
Lube: 1-shot
Max Spindle Speed: 3250
Made: Taiwan
jpmsteadi
Posts: 43
Joined: Fri Feb 19, 2021 5:51 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: E415F6F1121A-1204204111

Re: Mill Choice PM-728VT or PM-833VT

Post by jpmsteadi »

Richard,

I own the 728VT but have not see the 833 in person. I have seen some videos of a conversion to that as well.

I would say that the 833 is the better choice if you think you might be doing anything but aluminum. The 728 does have a slightly faster max spindle speed, which is handy for small tools in aluminum, but in making parts I have found the BLDC motor of the 728 to not work particuarly well at any sort of material removal rates.

Having an additional HP of power and a proper VFD will make the 833 more useful I think.

That being said, I think you can do good things with the 728 as long as you stay within the parameters of it. Were I to purchase a machine again I don't think it would be the 728. ITs a great machine, but I outgrew it quickly.
RJS100
Posts: 25
Joined: Tue Oct 20, 2020 8:41 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: none

Re: Mill Choice PM-728VT or PM-833VT

Post by RJS100 »

Thanks for your insight. That is very helpful. I will seriously consider the PM-833VT.
All the best... Richard
RJS100
Posts: 25
Joined: Tue Oct 20, 2020 8:41 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
CNC Control System Serial Number: none

Re: Mill Choice PM-728VT or PM-833VT

Post by RJS100 »

Thanks for your insight. That is very helpful. I will seriously consider the PM-833VT.
All the best... Richard
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