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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Precision Matthews PM-728VT Mill for CNC ?
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  1. #1
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    Precision Matthews PM-728VT Mill for CNC ?

    I'm considering getting a Precision Matthews PM-728VT benchtop mill for CNC conversion. I think this is a very new machine but I'm wondering if anyone here has used one. It's from Taiwan rather than mainland China. I have a larger knee mill and 14" Goodway lathe from Taiwan which I've been very pleased with, though those are both 40+ years old.

    PM has another mill, a PM-833T or PM-833TV, that is from Taiwan. I suspect similar quality to the PM-728. Anyone have experience with these?

    Any thoughts on a CNC conversion of the PM-728VT? No kits for this conversion but shouldn't be too difficult.

    Thank you for your help.

    Hugh

  2. #2

    Re: Precision Matthews PM-728VT Mill for CNC ?

    That looks like a nice size mill for many hobby users. I bet it will be popular for conversion. Being already setup for oiled ways is a nice touch too. And the belt drive would lend itself to tossing a bigger motor on there with ease.

    I've looked at the 940M with hardways a number of times. PM is about 15 minutes from my house. I'd probably go that route if I were to get a PM machine, but I have a G0704 now, so something marginally larger than it isn't too attractive. I'd rather make a big jump.

  3. #3
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    CL_MotoTech:

    It looks like a good mill. Pretty much the same size as the PM-25MV and the G0704. It's some 100lb heavier and, with luck, a step up in quality coming from Taiwan.

    I don't see the PM-940M on their website. There's a PM-935TS and a PM-949TS both knee mills from Taiwan. Likely the same with table size 35" & 49". I have a 40+ year old SuperMax knee mill (Bridgeport copy) from Taiwan converted to CNC and I've been very pleased with it. However, it's now in storage with no way to set it up where we currently are. I'll have enough trouble fitting a PM-728 and a 10x22 lathe in the given space. The PM-833TV would be a nice size and may be as stout as a small knee mill? It would likely be easier to convert for CNC than a knee mill.

    I have a CNCed Sherline mill/lathe with me. But I'm starting to lust after a little bigger machine(s). Just acquired a shed with, hopefully, space for some benchtops.

    Would love to hear from anybody out there who has experience with Precision Matthews Taiwanese mills. They seem to be rare but someone must have undertaken a CNC conversion, or at least used one enough to give feedback.

    Thanks.

    Hugh

    Quote Originally Posted by CL_MotoTech View Post
    That looks like a nice size mill for many hobby users. I bet it will be popular for conversion. Being already setup for oiled ways is a nice touch too. And the belt drive would lend itself to tossing a bigger motor on there with ease.

    I've looked at the 940M with hardways a number of times. PM is about 15 minutes from my house. I'd probably go that route if I were to get a PM machine, but I have a G0704 now, so something marginally larger than it isn't too attractive. I'd rather make a big jump.

  4. #4

    Re: Precision Matthews PM-728VT Mill for CNC ?

    You're looking in the wrong section, mate. The 940 isn't a knee mill.

    https://www.precisionmatthews.com/shop/pm-940m/

    I doubt you'll hear too much on a newly released mill. PM25 conversions are less common than G0704 conversions, despite being relatively similar. That said, with some research it shouldn't be too hard.

  5. #5
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    That really looks nice. One thing I like about it is that the column looks to be substantial where it is attached to the base. The specs say there are 4 bolts that attache it but I can't see them in any pictures. I hope they aren't up through the bottom. I have a G0704 and I have never liked how the column is attached. This stands to be much more rigid than my G0704. HOWEVER if the column is not perfectly square tramming it may be a pain.

    You should ask PM if they know of anyone who is making a conversion kit. If there are none out there, you will have to be the first, and in that case I hope you have access to another mill and a lathe.

    Also you should ask for some details on the motor drive. You will want to be able to control the driver with your system. It says the spindle is brushless DC. Find out what the driver is. If it is the same as the driver on their PM1228 lathe, then Little Machine Shop has a board you can use to control it.

    Oh, one other thing. There is no manual on the website, see if they can send you a draft copy.

    BTW, I love my PM1228 lathe. Very nice quality.
    https://www.cnczone.com/forums/verti...-software.html



    Good luck

  6. #6
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    CL_MotoTech:

    You are right, I missed that mill completely. It's big for a bench mill and looks very capable. Thanks for pointing me to it.

    I agree. I think the 728VT has only been out for a few months so I'm not surprised no-one is yet doing a conversion. Worth asking though. I'm sure a conversion wouldn't be too daunting, but more work than a G0702 or PM-25 where plans and kits are available. The question, is it worth the extra trouble and cost. The 728VT cost nearly as much as the 940M.

    I'd be real happy if I just found an owner who could comment on overall quality. Or even the quality of PM's Taiwanese machines compared to their Chinese ones. It's quite a premium in cost if there isn't much difference in quality.

    Thanks again.

    Quote Originally Posted by CL_MotoTech View Post
    You're looking in the wrong section, mate. The 940 isn't a knee mill.

    https://www.precisionmatthews.com/shop/pm-940m/

    I doubt you'll hear too much on a newly released mill. PM25 conversions are less common than G0704 conversions, despite being relatively similar. That said, with some research it shouldn't be too hard.

  7. #7
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    One thing I noticed is that the sadle is constructed much the same way as the PM25MV mill. So there should be enough space for a 1605 ballnut with no modification of the saddle itself.

  8. #8
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    maxspongebob:

    Yes, if bolted from below it would be difficult to shim the column. Is the G0704 bolted from below? There was a thread about the 728VT, I think on CNCzone, with a lot more pictures. I've lost it but will keep looking.

    I'd be surprised if there's a CNC kit out for the 728VT yet. It would be an adventure. I have a Sherline mill/lathe which would help, but no accessible larger equipment. I'll likely get a 10x22 lathe also to CNC. If I convert a bench mill I'll likely bring in the 10x22 before getting too far. It's doable.

    I'll ask PM about the spindle speed control. It would be nice to have spindle control but workable without. My Sherline hasn't been hooked up to control the spindle. I'll see if I can get a manual also.

    Good to hear the PM1228 is of good quality. From the specs it looks like a very nice lathe. A 12" would be a very nice size, I'm sad I can at most fit in a 10x22. The 1 1/2" spindle bore on the PM1228 is impressive. The D1-4 spindle would be nice also. With a 5MT spindle taper I think you can make a 5C-MT5 collet adapter that fits inside the spindle, very handy.

    Thank you for the help and direction. I'll report back if I find out anything useful.

    Quote Originally Posted by maxspongebob View Post
    That really looks nice. One thing I like about it is that the column looks to be substantial where it is attached to the base. The specs say there are 4 bolts that attache it but I can't see them in any pictures. I hope they aren't up through the bottom. I have a G0704 and I have never liked how the column is attached. This stands to be much more rigid than my G0704. HOWEVER if the column is not perfectly square tramming it may be a pain.

    You should ask PM if they know of anyone who is making a conversion kit. If there are none out there, you will have to be the first, and in that case I hope you have access to another mill and a lathe.

    Also you should ask for some details on the motor drive. You will want to be able to control the driver with your system. It says the spindle is brushless DC. Find out what the driver is. If it is the same as the driver on their PM1228 lathe, then Little Machine Shop has a board you can use to control it.

    Oh, one other thing. There is no manual on the website, see if they can send you a draft copy.

    BTW, I love my PM1228 lathe. Very nice quality.

  9. #9
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    maxsuongebob:

    That would make life easier. They show a picture of the saddle looking down the X axis including a tape measure. Looks like a good 2" space. I didn't see similar pic for the Y axis but I think it's for the X ballnut that the G0704 saddle needs to be ground down. I'm thinking this is why they show this picture. Encouraging.

    Thank you.

    Quote Originally Posted by maxspongebob View Post
    One thing I noticed is that the sadle is constructed much the same way as the PM25MV mill. So there should be enough space for a 1605 ballnut with no modification of the saddle itself.

  10. #10

    Re: Precision Matthews PM-728VT Mill for CNC ?

    There is certainly loads of room on PM saddle.

    The G0704 saddle is tight, not only does that saddle get machined, but the nut sometimes needs touched up too. And I ended up clearancing the underside of my table to clear the nut some. The PM25 and now this one look better in that regard. I like the PM table better too. That said, I'm not sure any of these things offer any true advantage beyond just preference.

    I can't attest to the better quality of the Taiwanese manufacture, perhaps you should give PM a call and see what they have to say. Obviously they think the price is justified, but it would be nice to hear what they have to say. Whether or not you see a meaningful difference could very well depend on the type of work you do. For example, with my G0704 I can consistently achieve great results with reasonable ease in aluminum. I was machining the inside race of a bearing the other day, and to get reasonable results took quite a bit more work. The harder material makes quite a bit of difference in the machines abilities. The 100lbs and better column mounting probably help the 728, but how how much and to what end is the question. From there, is the additional cost justified? It's hard to say. I'd probably go for the larger machine, but I have the space.

    All of this in mind, if you only have so much space, try to get as much machine in that space as possible. Keep in mind, you'll have to move the thing around. I can just barely move my G0704 if I remove the table and head. With two people it's pretty easy though.

  11. #11
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    Keep in mind, you'll have to move the thing around. I can just barely move my G0704 if I remove the table and head. With two people it's pretty easy though.
    Renting an engine hoist takes a lot of stress out moving these things, especially the largest bench tops. How well that works may depend on the height of the ceiling.
    My 'bench top' is ~1200 lbs assembled and I managed it solo though it would be much wiser have a helper for safety.
    Anyone who says "It only goes together one way" has no imagination.

  12. #12

    Re: Precision Matthews PM-728VT Mill for CNC ?

    I used a lift with the G0704 the first time I moved it, it wasn't bad. But it's unnecessary, and if your space is tight, it might even be impossible. When I moved my G0704 into my basement it was impossible. They don't do well with stairs, especially not 30" wide stairs. With a 1200lb. machine you aren't moving it without assistance, and in a small space it's likely impossible to have such a machine.

  13. #13

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    Re: Precision Matthews PM-728VT Mill for CNC ?

    That mill has some really nice features!
    The x and y screw mounts look very similar to those on a PM-25mv, and the bed is close to the same size, just has more travel on the z and y axis.

    Conversion shouldn't be any harder than a PM-25mv- there are plans out there for that mill, just make whatever adjustments to the parts as needed.

  14. #14
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    CL_MotoTech:

    It looks like good clearance on the PM728. Good to hear the PM25 is better than the G0704. Plus one for Precision Matthews.

    The description of the PM728 I think gives an indication of their thinking. "If You Want The Best, This Is It. This machine is 100% Made in Taiwan. It Costs More, But You Get More. Much More. The Highest Level of Quality and Precision in a Bench Top Mill Available Anywhere." The question is how much do we believe their PR.

    I have always had trouble hitting bearing bore, or shaft, tolerances. I think next time I find a critical one I'll try to lap it to size. Would take a lot longer but could get to the fit wanted.

    That is the magic question, whether the extra cost is worth what you get. And the answer is likely to change from person to person. So gather all the info you can and make an informed decision. I'm trying to do this.

    My current predicament is very limited space. It's sometime hard to move machines around, but once they're in place your set.

    Thanks.

    Quote Originally Posted by CL_MotoTech View Post
    .... I ended up clearancing the underside of my table to clear the nut some. The PM25 and now this one look better in that regard....

    I can't attest to the better quality of the Taiwanese manufacture, perhaps you should give PM a call and see what they have to say. Obviously they think the price is justified, but it would be nice to hear what they have to say.....I was machining the inside race of a bearing the other day, and to get reasonable results took quite a bit more work. The harder material makes quite a bit of difference in the machines abilities. The 100lbs and better column mounting probably help the 728, but how how much and to what end is the question. From there, is the additional cost justified? It's hard to say. I'd probably go for the larger machine, but I have the space.

    All of this in mind, if you only have so much space, try to get as much machine in that space as possible. Keep in mind, you'll have to move the thing around. I can just barely move my G0704 if I remove the table and head. With two people it's pretty easy though.

  15. #15
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    cyclestart:

    That makes sense for benchtop machines. I'm moving over gravel, but putting a sheet of plywood down would solve that. So borrow or Harbor Freight a lift (no rental places anywhere close). Once inside I can use a block and tackle or small chain hoist to get it on a stand.

    Thanks.

    Quote Originally Posted by cyclestart View Post
    Renting an engine hoist takes a lot of stress out moving these things, especially the largest bench tops. How well that works may depend on the height of the ceiling.
    My 'bench top' is ~1200 lbs assembled and I managed it solo though it would be much wiser have a helper for safety.

  16. #16
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    CL_MotoTech:

    For a basement you can cut out the floor, build a hoist and lower machines in and out. It is possible but a little scary.

    Attachment 433584

    Once on the right floor they can be scooted around without lifting. Either walking with a pry bar or using pipes as rollers. Works well on concrete but not sure it'll work on a wooden floor.

    But if it's too large for the space through, it's just too large whether you can move it or not.

    For benchtop machines an engine hoist and then using a small chain hoist and rafters should get the job done. At least they don't have to go into a basement.

    Thanks.

    Quote Originally Posted by CL_MotoTech View Post
    I used a lift with the G0704 the first time I moved it, it wasn't bad. But it's unnecessary, and if your space is tight, it might even be impossible. When I moved my G0704 into my basement it was impossible. They don't do well with stairs, especially not 30" wide stairs. With a 1200lb. machine you aren't moving it without assistance, and in a small space it's likely impossible to have such a machine.

  17. #17

    Re: Precision Matthews PM-728VT Mill for CNC ?

    Depending on how much time you have to devote, and how much money you want to spend, you might be better served by converting a new PM25 or G0704 to linear rails. You could cast it full of epoxy granite while you're at it. Done right, it might be better than a 728 conversion but significantly cheaper. Granted, it will be a lot of work. Heck, even my G0704 conversion has been a lot of work, and it still has ways, but linear rails really take these machines to the next level.

    That said, linear rails are a big project. What you need to decide is how precise you need to be, and if that's achievable by less costly machines. There's a fair chance it is, but, the 728 is probably quite square and easy to setup. There's value in that. I've spent quite a bit of time adjusting my G0704 over the years. Probably tens if not hundreds of hours. I've even replaced the table and z-carriage after realizing they were sub standard. Some decent QC would be have been great, but if you circumvent the QC all together then the cheaper machine probably wins.

  18. #18

    Re: Precision Matthews PM-728VT Mill for CNC ?

    I dont think my land lord would have liked me poking holes in the floor.

    I own a house and detached two car garage now. Space isn't unlimited, but I don't have to worry about the 30" wide stair case either.

    Here's my G0704.


  19. #19
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    Brian:

    I do like the PM-728 at least on paper. Looks like it fits my needs better than any other I've seen.

    I hope you're right, that there are no unforeseen difficulties. The conversions of the PM-25 appear straight forward. The only difficulty beyond the PM-25 is you can't get specific plans. Plans for the PM-25 would be a good start though. I've found, and downloaded, plans from "Franco". Also plans for the G0704. If you know of others for the PM-25 I'd like to hear of them.

    I would like to tuck the Y axis stepper towards the machine, using a timing belt to the axis, rather than sticking out from it. (Yes space is that tight) Likely have to have the machine in hand to see if this is possible though. But a basic conversion looks doable if not easy.

    Thank you for the thoughts.

    Quote Originally Posted by BrianPM View Post
    That mill has some really nice features!
    The x and y screw mounts look very similar to those on a PM-25mv, and the bed is close to the same size, just has more travel on the z and y axis.

    Conversion shouldn't be any harder than a PM-25mv- there are plans out there for that mill, just make whatever adjustments to the parts as needed.

  20. #20
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    Re: Precision Matthews PM-728VT Mill for CNC ?

    CL_MotoTech:

    For me going to linear rails is a step too far. I'm not sure I'm capable of setting such a machine up and getting better than factory performance. I would certainly hesitate without having another good mill to make parts for the project mill. Nope, a G0704 or PM-25 would likely be fine for the stuff I make. But if the PM 728 reduces the frustration and having to work around machine quirks it's likely worth it to me.

    I've toyed with the idea of scraping a small lathe, like a 10x22. More likely I'd go this direction than linear rails for mill or lathe. I'll have to invest in the tools for scraping and see if it's something I want to tackle. But most likely I'll get a mill and lathe set up for CNC and get too busy using them. Too little time.

    Thanks.

    Quote Originally Posted by CL_MotoTech View Post
    Depending on how much time you have to devote, and how much money you want to spend, you might be better served by converting a new PM25 or G0704 to linear rails. You could cast it full of epoxy granite while you're at it. Done right, it might be better than a 728 conversion but significantly cheaper. Granted, it will be a lot of work. Heck, even my G0704 conversion has been a lot of work, and it still has ways, but linear rails really take these machines to the next level.

    That said, linear rails are a big project. What you need to decide is how precise you need to be, and if that's achievable by less costly machines. There's a fair chance it is, but, the 728 is probably quite square and easy to setup. There's value in that. I've spent quite a bit of time adjusting my G0704 over the years. Probably tens if not hundreds of hours. I've even replaced the table and z-carriage after realizing they were sub standard. Some decent QC would be have been great, but if you circumvent the QC all together then the cheaper machine probably wins.

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