Possible Purchase of PM-25MV

[AlanB]

I got some boards from Mesa Electronics to use with LinuxCNC instead of a regular parallel port. They have FPGA based pulse generators instead of depending on software timing. I haven't bought the mill yet so haven't configured/tested it all yet. Need to make space for the mill to land first...

When I bought my lathe I picked it up at the depot using a small utility trailer. They forklift it onto the trailer, and I used cargo straps to hold it in place. Then I can back the trailer very close to where it goes, and disassemble into components or lift with friends or engine lift. Works out really well.

 

[devils4ever]

shooter: Okay, I think I got it. The 1605 is the diameter (16mm) and the 05 is the pitch (5mm)? The BK12 and BK15 are some standard for the ends? C7 is the precision level?

I've read that double ballnuts take more space and can limit the range. Is this true here? Should I stick with single?

Grinding them down should be no problem.

Mike: Is the G0704 kit the same as the PM-25MV kit? Will it work here?

I've been looking at the Fusion 360 CAD and CAM software. There's definitely a learning curve there!

Can double-ended stepper motors be used so that a handle can be placed on the free end to make it work manually?

I'm starting to understand all this CNC conversion stuff.

 

[macardoso]

Okay, I think I got it. The 1605 is the diameter (16mm) and the 05 is the pitch (5mm)? The BK12 and BK15 are some standard for the ends? C7 is the precision level?

Bingo. you got it. The BK code sets the bearing and thread diameters and lengths. They're setup to match commercial ballscrew end supports, but you can also design your own. C7 is an accuracy grade which specifies how many thou of lead error per foot of travel (if you were to look at any 12 inch section of screw, the lead error would not deviate more than .000x" from ideal).

I've read that double ballnuts take more space and can limit the range. Is this true here? Should I stick with single?

Double ballnuts chew up space but reduce backlash. I would say backlash contributes 10x the issues in hobby machines compared to screw lead error. I would definitely try to get the double nuts to work.

Grinding them down should be no problem.

Careful about getting dust in your screws.

Is the G0704 kit the same as the PM-25MV kit? Will it work here?

The machines are very similar, however even between two identical machines, there will be manufacturing differences. Expect to do some light hand fitting or measuring/modification of the design.

I've been looking at the Fusion 360 CAD and CAM software. There's definitely a learning curve there!

Fusion is great and has an amazing community. You can also get Autodesk Inventor on free 3 year licenses if you download the educational version (no restrictions or watermarks). Inventor is kinda the big brother of Fusion. More used in industry, smaller hobby community.

Can double-ended stepper motors be used so that a handle can be placed on the free end to make it work manually?

Can it? Yes. Do you want to? No. Ballscrews have very little friction compared to ACME screws that the machines ship with. If you try to cut without the stepper motors powered on, the cutting forces will push the other axes around. You can get around this by locking them, but it just isn't very useful. I had them on my machine for 3 years and never used them once. Spend the effort getting yourself setup with a good MPG.

 

[shooter123456]

Okay, I think I got it. The 1605 is the diameter (16mm) and the 05 is the pitch (5mm)? The BK12 and BK15 are some standard for the ends? C7 is the precision level?

Correct. Except the C7 part. I believe C7 refers to accuracy, not precision.

I've read that double ballnuts take more space and can limit the range. Is this true here? Should I stick with single?

They are longer when there are 2 nuts, but you won't lose any travel. Stick with double nuts because they are preloaded against each other to reduce backlash. The Y axis is the only place where it is close, but even with the long double nuts I got with the ground screws, there is no loss to travel.

Mike: Is the G0704 kit the same as the PM-25MV kit? Will it work here?

The machines are similar, but different enough that they can't be considered interchangeable. The way the Y axis nut attaches to the saddle on the G0704 is with a slot cut in the saddle while the PM25 uses a round boss that feeds up into a corresponding hole in the saddle and screwed in from the top. On the X axis, the G0704 also uses a slot, while the PM25 has a machined area with 2 threaded holes where the ballscrew holder is attached. The Z axis is probably closest on the two, but I would not bet on them being close enough to be used interchangeably.

Can double-ended stepper motors be used so that a handle can be placed on the free end to make it work manually?

I wouldn't. You would need to lock the axes manually that aren't being used, and ballscrews don't work great manually. It is easy enough to control the machine manually through the software that there really is no need.

 

[devils4ever]

At this point, I'm thinking about getting the mill with the DRO and playing/learning with it manually for a while to get used to it. Then, switch to CNC.

I just need to sell my wood shaper to make room for it and to raise some cash.

 

[Bill Kahn]

... I bumped the speed up to 5500 RPM ...

Can you describe how you did this speed “bump?” Or give a pointer to where it has been described? Thanks. -Bill

 

[shooter123456]

Can you describe how you did this speed “bump?” Or give a pointer to where it has been described? Thanks. -Bill

I made new pulleys, removed the quill assembly, and made a plate to hold a bearing to support the top of the spindle.

I feel like that sounds a lot more complicated than it was, because it was just making 3 new parts and removing 1 old one. Not much to it.

 

[devils4ever]

Okay, I did it! I just placed my order and decided to get the non-DRO version since I'm fairly certain I'll be adding CNC. Now, the wait begins....

 

[devils4ever]

So, I've been thinking about how to get this thing in my basement and on top of the stand (I ordered the factory stand). I can do some disassembly if needed, but would prefer a minimal amount.

So, based on DarryIN's post, I'm thinking I can use a winch of some type and 2X4's to move it up and down the stairs (maybe, after removing the table). I see both types of winches are available: come-along style and the chain hoist style. I've used a come-along before and wasn't impressed. My winch broke trying to pull my car out of a small snowbank years ago. Can the chain hoist style be used on a ramp? I usually only see them lifting vertically.

 

[matthewsx]

You're going with the PM-25 right? At only 275lbs I'd just call up one of my buddies and take it downstairs with a furniture dolly.