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  1. #1
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    Mar 2017
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    33

    Nico's PM-25 CNC Build

    I have learned so much on this forum over the years and I figured it was time to give something back and share my machine. It is a PM-25 MV that I purchased in January of 2018.

    Currently, parts and modifications include:
    400 oz in Nema 23 steppers on X and Y
    1200 oz in Nema 34 stepper on Z
    DM542T drivers for X and Y
    DM860T driver for Z
    2 48v power supplies
    1500W 6000 RPM Lenze MCS servo on the spindle
    1605 double nut ballscrews on X and Y
    1605 single nut ballscrew on Z
    Power draw bar
    Full enclosure
    Linux CNC control
    Mist coolant system
    Angular contact bearings in the spindle (Running 7500 RPM now)

    I use the mill mostly for making parts for the machine or making gun parts. It uses a mix of TTS tool holders, shop made tool holders, and some Novakon tool holders.

    Overall, I am happy with the performance of the machine. My biggest complaints are the double nut ballscrews (they came severely bent and needed lots of work to get the nuts to fit and preloaded, got a refund for them though), the spindle (vibrates a little bit more than I would like at 7500, needs to be balanced), and the Y and Z way covers (didn't last long before tearing and eventually got removed). At some point, I will remove the spindle again and see about balancing it. There was some poor machine work on the spindle threads which makes the cap that the drawbar uses wobble. That is certainly contributing to the vibration. I would like to increase the spindle speed to 10,000 once I do that, and the 2 HP servo should be more than capable of removing material at 6000 RPM. The torque output at 6000 is still well above what most cuts would require. I usually run it at roughly 1 in^3/min removal in aluminum, though I have managed to get it to cut 4.35 in^3/min. With end mills, I need to stick to roughly 1, because too much higher and I get tool pull out. With carbide insert end mills, tool pull out hasn't been a problem.

    The pneumatic drawbar uses a 3 stage air cylinder running at roughly 110 PSI pushing 2300 lbs to release the tool. The springs I have are rated for 900lbs working force with 1100lbs full compression force. I have 12 of them running in 3 sets of 4 like this (())(())(()) so the release force is 2200 lbs.

    I have plans to change some things up on the machine in the future. I would like to make a new enclosure out of sheet metal so I can run flood coolant instead of mist. I currently have one made of MDF and wood sealed with epoxy paint. I am also planning a 10 tool umbrella style tool changer that has most of the parts machined, but I need to work on the programming and a few peripherals. I have my eye out for some ground ballscrews that I can afford on ebay, but so far I have not had any luck finding one that is suitable. I would like to put some servos on it, but it may be a while before I can justify that. If I can get the tool changer working and start running production parts to sell, I might be able to justify the increase in speed and accuracy. I will also be making a probe to help on that end.

    I am toying with the idea of converting it to linear rails to get some increased rapids and hopefully smoother motion. I made a linear rail table for my X2 once and it made a world of difference. I have a friend who has a Haas that can machine the dovetails off and prepare the rail mounting surface for me. I am not sure that makes sense at this point though since the dovetails do a good enough job. I would also like to increase the Y axis travel and put a head spacer on it. As others have mentioned, the machines spindle is not centered on the Y axis travel, so a lot of the Y axis travel isn't usable. A vise hanging off the end further limits that travel.

    I have an idea for a control panel for it since I don't love using a mouse and keyboard all the time. It is tough to keep all of it clean and most of the keystrokes could be replaced with a control panel button.

    I made a 4th axis/lathe attachment using the old spindle bearings and motor. I haven't used it yet, and currently it does not have positioning capabilities. I had an idea to add an encoder and a brake to give me 3+1 capabilities, but I haven't had a chance to design and test that part out.

    Here is the machine and the enclosure before the doors went on. The cut out in the back was there so I could get the tool changer mounted. The vise on the table is an inexpensive 4" ebay vise.


    Here is a look at the air cylinder assembly for the drawbar.


    Here is the 4th axis as it stands now.


    An AR-15 lower I made using the machine.


    There is a look at the spindle servo compared to the stock motor and the Z axis stepper.


    Thanks for looking! I am happy to answer any questions anyone has as well as suggestions or constructive criticisms to help me improve the machine.

  2. #2
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    Re: Nico's PM-25 CNC Build

    Thanks for posting, got any videos?
    I have a 2 axis Acer knee mill (Bridgeport clone) in excellent shape, but keep coming back to these 25 cnc conversions. I really would like 3 axis to play with


    Sent from my iPhone using Tapatalk Pro

  3. #3
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    Re: Nico's PM-25 CNC Build

    I have a few videos on YouTube.

    Here is a link to that channel:

    https://www.youtube.com/channel/UCL6...TdHHRC02FUttzA

  4. #4
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    Re: Nico's PM-25 CNC Build

    Thanks


    Sent from my iPhone using Tapatalk Pro

  5. #5
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    Re: Nico's PM-25 CNC Build

    It has been a while since I have posted anything here.

    Two big changes to the machine are the Clearpath servo motors on each axis and the automatic tool changer.

    The servos give me about 400 IPM in the X and Y, and the Z is able to move about 250. I am only using a 48V power supply, so those numbers should increase when I get a clearpath 75V power supply. I am very pleased with the servos. It is excellent having the machine not lose its position if it crashes and never having to worry about lost steps because I pushed it too fast.

    The automatic tool changer is an umbrella type tool changer on some round linear rails. It is actuated by a dual action air cylinder and rotated by a stepper motor. It holds 10 TTS tools. I am still working on the programming for it, but it will be controlled using an arduino responding to commands from the linuxcnc control computer.

    I posted a few videos showing the machines old and new rapids and some motion testing on the tool changer.

    https://www.youtube.com/watch?v=qHFJee4_-Gc&t=4s

    https://www.youtube.com/watch?v=4EZNl0tpySg

  6. #6
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    Re: Nico's PM-25 CNC Build

    @shooter123456. What is the model number of those Clearpath servos?

  7. #7
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    Re: Nico's PM-25 CNC Build

    CPM-SDSK-2321S-RLN on the X and Y, CPM-SDSK-3421P-RLN on the Z.

  8. #8
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    Re: Nico's PM-25 CNC Build

    Nice machine and nice work. Sound like you have a good grasp on it. I just received my clearpath motors for my pm940. My pm940 just came in a couple weeks ago so I can get ready to do a conversion on it. I have most of what I need but have to buy some ball screws. I have some AC bearings ordered so I can figure out everything. The 940 is a huge heavy mill and should make for a solid conversion. I will eventually build an enclosure. I have thought about using some 80/20 t-slot extrusion for the enclosure's upper frame. Do you know how you will build your enclosure?

  9. #9
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    Re: Nico's PM-25 CNC Build

    I have been working on the enclosure for a couple of weeks now. It uses steel square tube as a stand and sheet metal for the body. This is only my second excursion into welding and the first time I have worked with sheet metal. It will have a chip tray on drawer slides under the machine and the tray will have a drain for the coolant. I have not yet picked out a container to use as the coolant tank, but it will probably just be a plastic storage container. I am still trying to figure out how to do the doors, but I am thinking an aluminum frame with an acrylic sheet in the middle, then drawer slides to open and close. If you would pardon the mess, I have a few pictures of its progress.





    I also made a little adapter to hold the solenoid for the air blast I have been using. The mist coolant doesn't clear chips from holes very well, so in those cases, I use compressed air in addition to the mister.







    I am also working on re-doing the electronics enclosure. It was pretty tidy when I started, but as things were added, removed, and changed out, it has gotten messier and messier. I am going to rewire everything, get proper connectors for everything, and hopefully get it all cleaned up and organized.

    I am having trouble deciding how to replace the way covers. I tore through the stock ones within a few months, and am currently using a shower curtain as a temporary solution. I don't love the accordion ones because they seemed to tear pretty quick and they like to catch and hold on to chips. The sheet metal ones look like the best option, but they are either expensive or difficult to make work well. Anyone have any suggestions?

  10. #10
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    Aug 2016
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    Re: Nico's PM-25 CNC Build

    The Novakon pulsar has a sheet metal cover for its Y axis you can buy for $85. You could see if they'll give you a drawing of the flange to see if it will fit.

    Another option would be shielded bellows.

    https://www.novakon.net/collections/...-y-axis-pulsar

  11. #11
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    I'm messing around with 3d printed way covers for my G0704. If I can get it to work, I would epoxy on a thin piece of AL on the front face to protect the printed part face. I have a tentative design but have not made any scaled down pieces to prove out concept.

    Quote Originally Posted by shooter123456 View Post
    I have been working on the enclosure for a couple of weeks now. It uses steel square tube as a stand and sheet metal for the body. This is only my second excursion into welding and the first time I have worked with sheet metal. It will have a chip tray on drawer slides under the machine and the tray will have a drain for the coolant. I have not yet picked out a container to use as the coolant tank, but it will probably just be a plastic storage container. I am still trying to figure out how to do the doors, but I am thinking an aluminum frame with an acrylic sheet in the middle, then drawer slides to open and close. If you would pardon the mess, I have a few pictures of its progress.





    I also made a little adapter to hold the solenoid for the air blast I have been using. The mist coolant doesn't clear chips from holes very well, so in those cases, I use compressed air in addition to the mister.







    I am also working on re-doing the electronics enclosure. It was pretty tidy when I started, but as things were added, removed, and changed out, it has gotten messier and messier. I am going to rewire everything, get proper connectors for everything, and hopefully get it all cleaned up and organized.

    I am having trouble deciding how to replace the way covers. I tore through the stock ones within a few months, and am currently using a shower curtain as a temporary solution. I don't love the accordion ones because they seemed to tear pretty quick and they like to catch and hold on to chips. The sheet metal ones look like the best option, but they are either expensive or difficult to make work well. Anyone have any suggestions?

  12. #12
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    Re: Nico's PM-25 CNC Build

    Getting close to the end with the new enclosure. I have finished up most of the weld work, got the front opening all framed up, got new sliding rails for the doors, resized the doors from the old enclosure for use on the new one, mounted the doors, siliconed the corners where there was no sheet metal overlap, fabricated the chip tray, and I am now working on cleaning it up and getting it ready for paint. A few places will need body filler, but I am hoping the end result will look pretty good. I am planning to add the flood coolant tank and plumbing after painting everything and getting the machine moved over. The paint on the mill is looking pretty rough in some places, so the machine will also get a fresh coat along with the enclosure. I am planning to do the machine and lower part of the enclosure in gray and the upper and inside parts of the enclosure in white. I am picking white mostly because it will keep things bright inside.

    Here is the enclosure almost as it stands now. There is a little chip chute to funnel the chips into the tray which will sit on tracks below it.


    Here is a look at the inside looking down. The tape is there to help get nicer edges from the silicon. You can see the chip tray below and the chip chute as well.


    Here is another view of the chip tray down below. The tray will sit on sliders so it will be up a little bit higher. The gap should be about an inch, so hopefully it will manage to contain the majority of the chips.


    Just another look at everything. The doors mount to the .25" steel bars running across the top and bottom. Half inch steel square tube frames up the left and right side of the opening to stiffen everything up a bit and get rid of the sharp edge from the sheet metal. I am planning to add a piece of sheet metal folded over the bottom edge of the opening to protect that as well.


    I got a bunch of new connectors and such for the new electronics box as well. The number of connectors needed really adds up quick... I am hoping it will be worth it when I don't need to deal with the complete birds nest of wires running every which direction currently.

    Right now I am thinking the control panel will be mounted up on the front right, then a tool rack and accessory rack will be mounted to the left side. I got the casters in recently, so those will also soon be added to the frame.

    I thought I had pictures of the doors, but it looks like I do not. I will be sure to take some and add them. The door frames are made of aluminum and the windows are acrylic. I will be making some handles soon similar to the ones on the new tormach enclosures. There is still plenty of work to go. Need to figure out the automatic lubrication for the machine, way covers, motor covers (and waterproofing for flood coolant), control panel, head cover, spindle pulleys, air routing and control, and touch probe. I am sure that list will grow before I finish...

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