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[4]

pm25-mv z axis power feed

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mrjbinok

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#1
I recently purchased a PM25-MV and have decided that my first project will be to add a Z axis power feed. Adequate information of motor specs is in short supply, everywhere I have looked on the web, so here is what I decided to go with.... hopefully it will work out. One thing that I hope is that I will be able to avoid making any modifications that result in permanent changes to the basic machine.

https://vod.ebay.com/vod/FetchOrderDetails?itemid=372095953216&transid=1006962105024&ul_noapp=true

There are several different options for the type of motor to use and prices run anywhere from $30 to several hundred dollars. The right angle style geared motors have a better overall appearance for me and this will be my first choice.

I plan to use a transformer switching power supply with at least 30 Amp capability to allow for future additions. My motor is rated at 6 Amps at full load so this size power supply should be beefy enough to handle just about anything.

In addition to the basic up down control switching, I will be mounting upper and lower limit switches for protection, as well a sheer type coupling between the motor and the hand crank shaft.

I invite everyone to follow and contribute photos, thoughts, ideas, resources, links, dimensions, and recommendations here.
 

roadie33

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#2
Here is one from MrPragmaticLee on YouTube that he did on his PM Mill
I am going to do something like it for my G0704.
Just waiting on some warmer weather to go out to do the welding.

 

mrjbinok

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#4
It looks like this is for your transaction, can you post a public link to the motor?
What I got is a MAKERMOTOR brand

100 RPM
Nominal Current 6 Amps
Part Number PN01007-10038

https://www.ebay.com/itm/Makermotor...953216?hash=item56a2a5a940:g:HjEAAOSwXaZZ1W-b

Many of the motors I looked at do not have any actual torque specs to compare so I hope that it's gonna have enough UMPH to lift the head reliably. I also picked up two Eaton Yale Nylon Pinion Gears. 18 tooth, 1 5/8 diameter, and molded for a 5/8" shaft. This will be slightly smaller than the existing handle shaft so it will have to be reamed for fit. The motor shaft is 3/8 so I will have to turn a bushing that will press into the gear. Looking for matching gears was looking like a pretty expensive part of the project so I opted to modify these to fit and save some $$$.

I am working with my Cardiologist to get my BP meds regulated better so I can get out to the shop SOON!! That's an adventure that I hope I never have to repeat. In the meantime I will try to get some pictures of what I have bought so far and start laying out my drawings.

In the meantime be sure to follow Shooter 123456's modification thread. He's got some pretty interesting stuff going on!!

https://www.hobby-machinist.com/threads/new-pm-25mv-mill.65939/page-2#post-567497
 
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talvare

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#5
Many of the motors I looked at do not have any actual torque specs to compare so I hope that it's gonna have enough UMPH to lift the head reliably.
When I built my knee power drive unit, I determined the required torque by kind of going the "Flintstone" method. I had my Kurt vise on the table and stacked 200 lbs. of lead shot on the table as well. Since I had already machined part of my clutch drive assembly which also included a 1" hex for manual operation, I just used my torque wrench on the hex and raised the table, adjusting the torque wrench setting until I determined the minimum required torque to raise the table.
Just an idea you may be able to use.

Ted
 

mrjbinok

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#6
Just an idea you may be able to use.

Ted
Good idea Ted. Going "Flintstone" is how we as hobbyist's figure out what to do next!!

My problem with the lower cost 're-purposed' motors I've found on the web, is that they don't have any torque specs available, so you're kinda out there flapping in the breeze till you try something to see if it will work. I've hooked this motor that I picked up to a 12 volt power supply and it does seem to be a pretty hefty little motor. That's about as far as I have gotten with the project though. I am going through the medications maze following a mild heart attack to find something that will get me back on my feet so I can work out in the shop.

This is a scan of the only documentation I can find on this motor:

Z Axis Motor.jpg The "NOTE" applies to this motor
 

mrjbinok

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#7
I did finally find some torque specs on (of all places) Amazon

Product features

  • Rated Voltage: 13.5 VDC
  • Rated Speed: 100 RPM
  • Rated Load: 60 Watts
  • Rated Torque: 3 N-m (2.2 ft-lb)
  • Shaft: 3/8" shaft with 1 flat ("D" shaft) where flat to OD is 0.322" and the length of the shaft is 0.886" long

Now to do some research to get an idea on whether this will work or not!!

According to MrPragmaticLee's video above the motor he is using produces 42 inch pounds of torque.... This motor produces 26.4 inch pounds.

This might struggle a bit, but he states that a smaller motor may work just as well.... it was just what he had available. I think that going 'Flintstone' (Thanks Ted.... I like that phrase!!) is next on my list of things to look at.
 
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mrjbinok

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#8
I was finally able to get set up to see what kind of torque would be needed to raise the head on the Z axis. the MakerMotor is rated at 26.4 inch pounds and according my test I was able to raise the head with 15 inch pounds. That is without a final adjustment on the gib pressure.... just the way it came from the factory, so that may change once I do the adjustments.

With this in mind I'll start looking at how I will mount the motor and get the gears mated up to the crank handle shaft and the motor output shaft. Since I was working by myself to get the machine up to the workbench top, I had to remove the table, cross carriage, and the vertical column with the head. Took some time to get it moved, but now I will start cleaning everything up and put it all back together. FUN FUN FUN!!! Getting closer to making chips.
 

T Bredehoft

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#9
I have a Ford Windstar wiper motor on my PM25, it is plenty powerful, but I use it only for cranking the head up and down. not for cutting. It's about 60 rpm, six inches a minute.
 

mrjbinok

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#10
I have a Ford Windstar wiper motor on my PM25, it is plenty powerful, but I use it only for cranking the head up and down. not for cutting. It's about 60 rpm, six inches a minute.
That's about the physical size of this motor. The rated output rpm's on the motor/gear assembly is suppose to be 100 rpm's so this should work nicely. I had seen several write-ups and videos that had used around 75 rpm's and they all said that a little faster would be nice. There are several different variations on the MakerMotor website and they are available in quantity on fleabay. I plan to make some mechanical drawings of whetever support bracket I end up making so perhaps others will benefit in the future.

What did you do for a mounting bracket? Can you post a picture or two for ideas?

I don't plan to use the motor to raise and lower the quill for cutting.... just to position the head to minimize flex and vibration. For the most part I plan to use collets as tool holders for that reason. I'm new to milling operations so I'll likely have a large learning curve on what works for me and what doesn't. That's what is nice about these forums..... I have a whole array of folks with more experience to keep me in line. Thanks for contributing to my project.
 

T Bredehoft

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#11
For reason beyond my thinking, I mounted the motor to operate a toothed belt to drive the head. I could just as easily mounted it direct. The PM25 head crank is on the left at the top of the column. I fabricated a mount on the bearing retainer there mounted the motor on the back of the mount. I put too toothed pulleys on the other side of the mount, one on the motor one on the crank shaft. The hardest part was making an output shaft from the motor. as it comes it has a stub about 1.4" long, square with a rounded half. Originally a flat piece of steel was pressed on to this stub. Using the mill I carved a hole in the end of a shaft that went threw two bearings with the toothed pulley between them.

I wish I had more RPMs, seems to take forever running the head up and down, between using a drill chuck or a milling cutter. Fifteen seconds per inch for 2 1/2 inches isn't long, but If I had a 4 Inch quill I wouldn't have to do it.
 

mrjbinok

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#12
For reason beyond my thinking, I mounted the motor to operate a toothed belt to drive the head. I could just as easily mounted it direct. The PM25 head crank is on the left at the top of the column. I fabricated a mount on the bearing retainer there mounted the motor on the back of the mount. I put too toothed pulleys on the other side of the mount, one on the motor one on the crank shaft. The hardest part was making an output shaft from the motor. as it comes it has a stub about 1.4" long, square with a rounded half. Originally a flat piece of steel was pressed on to this stub. Using the mill I carved a hole in the end of a shaft that went threw two bearings with the toothed pulley between them.

I wish I had more RPMs, seems to take forever running the head up and down, between using a drill chuck or a milling cutter. Fifteen seconds per inch for 2 1/2 inches isn't long, but If I had a 4 Inch quill I wouldn't have to do it.
They must have changed the design in the column. My crank is on the top right (facing the machine) I didn't buy the bracket that they make for the motor so I will have to fabricate something to work. I hope to be able to piggyback the bracket and motor to the existing crank flange (rectangular) and I have two nylon gears that I will modify on the lathe to fit the two shafts..... and slot the mounting bracket to allow for fine tuning the gear mesh.

I started some drawings last night with my TurboCad. I've got a few other things to do this afternoon, but hopefully I can get started with the fabrication and lathe work this afternoon. I'll be taking pictures of the project and will be able to post the drawings when I get it done.
 

T Bredehoft

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#13
You are correct, I got it wrong, the handle/head drive is on the right facing the machine. I didn't know about a motor mounting bracket. Enjoy the experience of developing a solution.
 

mrjbinok

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#16
Did you post any pictures of the motor drive ? thanks,
Sorry no I haven't yet. All I have right now is the manufacturer's mechanical drawing.

I am really restricted right now by health issues. I haven't been able to get much shop time since I started the project. Hopefully I'll get my meds regulated and things will settle down soon
 

mrjbinok

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#17
I need to learn how to read the names on the post's !!!! Blame it on my meds!! ;)
 

mrjbinok

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#18
Well after several weeks of being my own doctor, I finally got medications straightened out and was able to use the machine for the first time today. Now I get to explain to my doctors where I got my medical degree!!

I had a couple of little projects that I wanted to try out with the machine before I actually started fabricating the motor mount for my Z drive. I'm really impressed with how easy the machine is to operate. Since I am new to milling everything has a learning curve so hopefully I can get started with this mod in the next few days.

I have all of the parts that will be needed so it is just a matter of mounting it and adjusting the gear feed. After today's run I will definately want to get the Z drive done sooner than later and the addition of the X drive will not be in the not too distant future! I'm basically a lazy guy and pushing a button to move the table is a lot more enticing than cranking the table back and forth manually!
 
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