PM-25. Making it faster. Pully Mods


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Thread: PM-25. Making it faster. Pully Mods

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    Member arizonavideo's Avatar
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    Default PM-25. Making it faster. Pully Mods

    That is PULLEY MODS!

    Hi guys. I have finally got around to playing around with a few mods for the PM-25 mill.

    I wanted to get a little more speed out of the spindle and fix the rattling stand problem. This is also the first lathe project for my son so its a team effort.

    The stock RPM is 2500 for the PM-25 which is better than some but not really that good for smaller bits. The motor seems to have good power in high range so I decided to see about getting some more speed.


    The first try was to make the spindle pulley smaller. It came off fairly easy held with a sets screw and it fit nice and snug.

    The problem was the spindle pulley had a large bore and they put a large keyway so you don't have much metal. I have a few cutters that I made to cut pulley groves so I took off .050" That left about .050" from the bottom of the grove to the top of the key slot.

    PM-25. Making it faster. Pully Mods-sany0077-jpgPM-25. Making it faster. Pully Mods-sany0078-jpgPM-25. Making it faster. Pully Mods-sany0079-jpgPM-25. Making it faster. Pully Mods-sany0079-jpg

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    Attached Thumbnails Attached Thumbnails PM-25. Making it faster. Pully Mods-sany0074-jpg   PM-25. Making it faster. Pully Mods-sany0075-jpg  
    Last edited by arizonavideo; 04-15-2017 at 04:18 PM.
    youtube videos of the G0704 under the name arizonavideo99


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    Default Re: PM-25. Making it faster. Pully Mods

    The spindle mod got me about 100 RPM, not near enough.

    The stock high speed pulley is a 1 to 1 ratio and the pulley is about 2.35" in diameter. To go from 2500 RPM to 4000 RPM I would need to make the pulley 1.6 times larger or about 3.76". There is just not room for that with the stock motor mount in the way.PM-25. Making it faster. Pully Mods-sany0097-jpg

    This is the pulley size that I think might fit without molding the mount.PM-25. Making it faster. Pully Mods-sany0099-jpg

    Its 2.73" in diameter. That should give about 3000 RPM.

    I had a 10mm reamer so a simple drill and ream gave us a nice bore that fit well.PM-25. Making it faster. Pully Mods-sany0095-jpg

    youtube videos of the G0704 under the name arizonavideo99


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    Default Re: PM-25. Making it faster. Pully Mods

    What kind of tool do you use for the groove profile. I'm considering making a multi-V pulley rather than V for my machine. Ditching the gears and going to pulleys for sure.

    CNC: Making incorrect parts and breaking stuff, faster and with greater precision.


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    Default Re: PM-25. Making it faster. Pully Mods

    First I'm going to let this thread die because I made a typo in the title.

    I'm mostly done with the pulley but I stopped because to fit the pulley I need to mill some on the motor mount and to remove the mount I need to un wire the motor. I can do all that but I needed the mill to work so I put it back together.

    For the tool.

    I ground a tool from carbide at 23deg using a diamond wheel. The only tricky thing is the point. The profile of the belts are flat but I found that a flat tip on the tool liked to wander on the lathe so the groove spacing would be off so I changed to a point. HHS should work fine.

    The belt profile is called J section belt.

    youtube videos of the G0704 under the name arizonavideo99


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