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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Milly McMillface, yet another PM25 conversion
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  1. #1
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    Cool Milly McMillface, yet another PM25 conversion

    Hey folks,

    I'll try to let the pics do most of the story telling...

    Decided to skip the PM stand after getting the idea of using the HF side tool cab from the physics anonymous boys (before they abandoned the PM25 for the bigger mill).
    https://www.harborfreight.com/145-in...net-64448.html

    drew a base, adaptor plate, and used franco's pm model to mock the bigger picture up:
    Attachment 442548

    for the base, I bought some 2.5in square tube from metalsdepot.com, cut them up with the 18 dollar blade from HF in my old craftsman mitresaw
    https://www.harborfreight.com/7-14-i..._q=metal+blade

    Attachment 442550

    Attachment 442552

    Set up on my professional grade welding table and got my metal glue gun out to make some sparks...

    Attachment 442554

    Attachment 442556
    maybe not too bad for a guy who sits in front of a computer all day...

    Attachment 442558

    time for a fit check...

    Attachment 442560
    that'll do pig. (no idea why this pic is previewing sideways, file is portrait)

    the feet for the base:
    Attachment 442562
    spent like 40 doll hairs to get these and really wish I didnt try to go by the numbers... more on that later


    Regarding lessons I've learned in just the base operations-

    pay attention to where the metal tube seam is if it's a piece that needs to be made holy. putting a hole in a seam turns drill bits into more bits.

    drill and tap all holes before welding, using a drill press is butter, and trying to use a hand drill on a big honkin assembly is for the birds.

    if intuition tells you to go bigger than the numbers suggest, go bigger. I chose these feet because they were "rated" for 750lbs a piece and I figured my mill wont possibly encroach on those numbers. Now although the mill is mounted and the structure stands just fine, the feet are a questionable point - the floor is wildly unlevel and even the stresses of trying to level the mill have the rubber coming off the bottom of the feet and with them screwed "out" almost all the way in some spots I'm concerned about lateral transients from moving vises and work around on it... if anyone has idea for swapping them out without disassembling everything please speakup!

  2. #2
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    Re: Milly McMillface, yet another PM25 conversion

    On to the adaptor plate for spreading out the PM's weight and allowing for boltification...
    I started out with just square tube from lowes but later became worried and added keystock to the mix being worried the thin walled tube might not hold 300+ lbs?
    Attachment 442564

    tacked in place
    Attachment 442566

    painted and standing in place in my grimy basement
    Attachment 442572

    Mill arrived a few days before... and my shop foreman overseeing activities...
    Attachment 442574

    piecing her down so I can carry its into the basement...
    Attachment 442576

    Attachment 442578

    Attachment 442580

    and at this point I realize that all portrait photos im uploading are being rotated... is there a way to fix this?

  3. #3
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    Re: Milly McMillface, yet another PM25 conversion

    I wanted to go back and add into my first post, but discovered there's an expiry of edit buttons here on cnczone- the edit I wanted to put in was a thank you to all the folks who shared their PM-25 cnc conversion build info online. Franco's youtube content was a great input and user @shooter1234546 has been an absolutely huge help to me in this process! And theres many other I havent mentioned, if youre on youtube with a PM25 in anyway, MUCH thanks!!!

    Now that the mill's been mounted up on the tool cab, I'm still attempting to level the whole base by the feet which is proving far more difficult that I imagined.


    Attempting to tram it out I realize the head seems to have a nod forward (that shows through my indicator hanging off the spindle-face) of about 4 thou. Took me 15mins to get the tilt (L/R) to show 0 on both side with a rubber mallet after loosening the head screws, but I cant seem to figure out how to get the nod out. I emailed PM and they suggested checking the column square-ness before potentially adding shims.

    I ordered some machinist squares and will be attacking that next.

    I've received my mesa hardware (6i25 and 7i76) and will be runing linuxcnc on an old computer I had lying around. (I started with a DB25 breakout board I later discovered had blown inputs)
    I bought CL86Y drives, NEMA24s for X & Y, and NEMA34 for Z from stepperonline.
    I made my own motor cables out of 12g wire which I regret, should have gone 16 or even 18 since the connectors were obviously not for 12g...
    I bought VGA cables from monoprice for 5 bucks a pop and am cutting them up to use as shielded encoder cables.
    The switching power supplies I got off amazon, plan to power the X&Y off one large meanwell and the Z off it's own separate supply, all at 48v.

    I plan to layout the entire control system and get her to chooch on the bench before installing anything.

    Motor mounts I'm hoping I can design maybe with some help models to 3d print then later mill (as a first test of the mill)

    Things I have in the mail:

    Ballscrews and supports from Sophia at Terry Machinery (no link, all email correspondence)

    AC Bearings from MOCHU bearings on ebay, about $45-55 a pair

    A cheap 5 in vise off amazon (I plan to have a kurt in my future, but feel the need to cheap out here for now).

    123 blocks and a square set.

    a pack of 10 prox sensors I want to use for limit switches, also got a set of 3.5mm stereo audio connectors to connectorize them.

    8ch opto isolator for prox sensors (they need 6-24v drive and 7i76 only spits out 5v IIRC)

  4. #4
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    Re: Milly McMillface, yet another PM25 conversion

    48v will be crap for a nema34 on the Z.
    I have a 1090oz/in on mine, 5.6A with an inductance value of 3.5mh running on 60V.
    It runs freezing cold even set at full 7.8A. Can only rapid up to 2000mm/min before premature stall.
    It's crying out for at least 80v to feed it.

    My 23's on x&y have only gone to 3000mm so far and will go more without stall
    These are also on the 60v.

  5. #5
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    Re: Milly McMillface, yet another PM25 conversion

    Thanks for the input! Where you source your motors from?

    the 24's I have are only rated up to 50v and I'm told you risk cooking em running them much higher.

    the 34 I bought is rated up to 80v I think but I was gonna see if I could get aay running at 48... maybe I'll have to bump it to 60... no idea yet

  6. #6

    Re: Milly McMillface, yet another PM25 conversion

    I don't think the voltage will make or break you. There's a long list of other items to get in order before you have to worry about these control issues.

    I like your fabrication skills, and you are doing good work, however I think in the long run if you get the machine really working you'll find that designing around what is still a manual mill is probably a mistake. I'm not trying to discourage you, keep up the hard work, just don't be surprised when you pretty quickly realize what you have done isn't really appropriate. The good news is that you are perfectly equipped to evolve the design as needed.

    Also, skip the Kurt and buy a Shars 4" vise. A 5" vise will work on this machine, a 6" vise is too big although workable. 4" vises however really are the sweet spot, I run two of them at times on my G0704. I have a 6" vise that I use too, but it dwarfs the table and is just too much vise for the majority of ops.

  7. #7
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    Re: Milly McMillface, yet another PM25 conversion

    Quote Originally Posted by CL_MotoTech View Post
    I don't think the voltage will make or break you. There's a long list of other items to get in order before you have to worry about these control issues.

    I like your fabrication skills, and you are doing good work, however I think in the long run if you get the machine really working you'll find that designing around what is still a manual mill is probably a mistake. I'm not trying to discourage you, keep up the hard work, just don't be surprised when you pretty quickly realize what you have done isn't really appropriate. The good news is that you are perfectly equipped to evolve the design as needed.

    Also, skip the Kurt and buy a Shars 4" vise. A 5" vise will work on this machine, a 6" vise is too big although workable. 4" vises however really are the sweet spot, I run two of them at times on my G0704. I have a 6" vise that I use too, but it dwarfs the table and is just too much vise for the majority of ops.
    Hey thanks for reading!

    I'd say it's not a mistake, but a known shortcoming. I certainly realize this $1700 import mill won't be remarkable. This project was started because I'm tired of waiting to find a place with more space. Too many projects and ideas on hold. The main purpose of this particular project is the learning. This is my first conversion, but I've done a retrofit before. This will definitely not be my last cnc mill... I would LOVE to do a full up build like VinceBuild did, but I have a lot to learn before attempting that and you need some tools at your disposal to go from the bottom up like that. For now, I'm just trying to find out what the best I can do is given what I got!

    thanks for the tip on the shars! will save me a pretty penny too it seems...

  8. #8

    Re: Milly McMillface, yet another PM25 conversion

    Just for reference, I run my G0704 opn 48V and I get consistent 145ipm rapids on Z with a 906oz/in nema 34. That's with a PDB and large BLDC on the head. If I were to up the voltages it would be to try an get better XY rapids. 200ipm I think is ideal for this size mill, but I am only comfortable with 170ipm with my current setup. I like to keep my ways very tight and at faster rapids I get occasional loss of steps.

  9. #9
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    Re: Milly McMillface, yet another PM25 conversion

    Bearings came in from MOCHU on ebay...
    Attachment 442972

    Attachment 442968

    I thought the "V" was supposed to line the bearings faces up? I guess not...
    Attachment 442970

    Still waiting on ballscrews and FK/FS supports.

    Also discovered the one power supply I was planning on using isn't quite as good at regulating as I hoped... running one nema24 on the bench the output drops from 48 to 38. Tried the meanwell PSU and she's rocksolid, though much louder than the other one...

  10. #10
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    Re: Milly McMillface, yet another PM25 conversion

    Ballscrews arrived
    Attachment 443230
    looks like the Z ballscrew fell out of one end and was banging around in the package a bit...

    Attachment 443232

    Attachment 443234

    Attachment 443236

    Attachment 443238

    Attachment 443240

    Attachment 443242

    I'll be honest I dont really understand the preloading hardware... the X and Y nuts have a screw on one end of that tab and a hole on the other, where the Z only has a screw on one end...

    I guess I'll learn all about it when I have to take the Y nut apart to grind it down...

    I also ran a real quick (very much unfinished) print of an idea for limit sensors that I'm planning on using for the X axis...
    Attachment 443244
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    I tested these with the mesa 7i76 card and running a 12v switching supply as a VFIELD/VIN source and they work as expected.

    Supports for the screws were shipped later, and I'm trying to CAD up some motor mounts soon.

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