PM-25MV ball screws, steppers...

[BrianPM]

Greetings- this is my first post, so I'll do a brief intro before asking pertinent questions.
I've been searching/following this forum for several months now, and just officially joined today.
I'm not a machinist by trade (organic chemist) , just a tinkerer, and after hanging out with a friend who manages a machine shop, I've come to understand the power of CNC. My friend offered me an old bridgeport for $500, but I had to turn him down, because I don't have the floor space in my garage, nor the availability of power to run one- even with a VFD/phase converter, I'd be stretching the old electrical service in my house. The problem is that him offering me this machine got me obsessed with obtaining a milling machine...
This has brought me to researching mini-mills, benchtop mills, etc... I already own a Grizzly 7x12 lathe, and have quickly learned the abilities and limitations of it, so I wanted to get the largest machine that will fit in my workspace. I decided on and ordered a PM-25MV because it has a few features that I want (belt drive spindle/brushless DC) and didn't have what I don't want (stand).

I've poured through many threads, and spent several hours researching CNC conversions, but am left with a few questions.

-I'm looking at 570oz/in steppers for X and Y, but am not sure what I will need for Z axis... I'm a bit unclear as to whether a 570oz/in would be suitable for Z axis or I need to use a NEMA 34 motor.

-Does the PM-25MV use the same ball screws as the G0704?

Software/hardware- I'm a little foggy on the way Mach 3 or other software interface with the controllers... Does it use a parallel port to plug directly into a C10 Breakout board, or do I need a smoothstepper board? (unfortunately all of my computers run windows 10, 64bit).

Thanks!

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[109jb]

On the Z-axis motor, I have a G0704 and the 570 oz-in does fine, but if I were to do it again I'd probably go with the NEMA 34.

I can't say if the PM25 would use the same ballscrews or not.

As far as electronics, you have options.

First is parallel port control where the parallel port of the PC connects to a breakout board (C10 or other) and the motor driver connect to the BOB.

A smoothstepper or similar device would connect to the PC via USB or ethernet. I would also connect to a BOB and then the BOB connects to the motors.

[dazp1976]

I've not long started on my conversion of a PM clone.
Parallel port on PC won't work with Mach3 under win10 64bit. You need a usb or Ethernet type interface.

Best thing to do in my opinion is to buy a cheap oldish PC and have it dedicated just to the machine. I prefer to keep it off the network and file transfer from my CAD/CAM PC using a usb drive. This is the way I do it with my existing small X2.

I'm using a Dell 780 I got for £30 which I wiped win10 off and fresh install of 32bit Winxp sp3. Runs perfect via parallel with a £5 bob..
I'm yet to get Win7 stable for some reason but I'm happy with xp so far.

I've got as far as almost finishing electricals and machine enclosure. Machine is next to do.
I'm plan on going well overboard with 1100oz/in x&y 1600oz/in z. Have the z motor but only have some 425's from my X2 atm for testing.

Now given the way may X2 works with 425oz steppers and tight gibs etc I'd be looking more than 570oz personally if planning to direct drive the ballscrews on a PM.

[CL_MotoTech]

900 oz/in is fine on Z. Some go larger, but I struggle to see where they gain. 500 oz/in on X and Y are definitely powerful enough. Once you get everything adjusted up all three axis will zip around trouble free with more than enough power to break end mills and bust drill bits.

If you want to stay Windows based then go with a UC300ETH motion controller, this lets you go with Mach 3 and UCCNC, or go with Acorn and their software/hardware. I use the UC300eth myself, i had a ESS before. I find I have less issues with the UC300eth.

I'd use a MX3660 or a G540. Both of these will make initial setup a breeze.

[arizonavideo]

The 6.1A Nema 34 640 oz stepper is a good match for the Z on the 25 mill.

The 570 oz Nema 23 is really the best bang for the buck ever for the Nema 23 size motors. I have run the 570 on the Z for years and it works fine but the 640 is only a few dollars more and some times drilling can use a lot of force.

For the 570 oz you want to keep the voltage under 60V that's why the larger Z steppers like the 900oz are not so good. They need more voltage to perform best.

[BrianPM]

Thanks everyone for the replies, you've given me a lot of good answers for me to look further in to.

[Zenji]

Make space for that 500buck mill and keep it manual, you can do real jobbing work on a bridgeport.
Do the cnc benchtop, keep both, never have to much stuff.

[hackish]

I'd suggest the acorn board. A lot of the stepper boards I looked at were truly hobbyist grade. I don't like steppers anyway, so I suggest watching for some cheap servos, but that's just me. I spent a bit of time using mach3, and althought there are a lot of fans, it turned out to be terribly buggy and unreliable. I'm a software guy by trade and the number of problems and bugs I encountered on the first run puts it at maybe beta level quality. When you start dealing with spinny metal parts, the last thing you want is a buggy controller.

[dazp1976]

I'd suggest the acorn board. A lot of the stepper boards I looked at were truly hobbyist grade. I don't like steppers anyway, so I suggest watching for some cheap servos, but that's just me. I spent a bit of time using mach3, and althought there are a lot of fans, it turned out to be terribly buggy and unreliable. I'm a software guy by trade and the number of problems and bugs I encountered on the first run puts it at maybe beta level quality. When you start dealing with spinny metal parts, the last thing you want is a buggy controller.

I don't mind Mach3.
I can only get it stable on Windows XP sp3.
Win7 for me was nothing but grief.
Fortunately I have a retail copy from back in the day.

I do have 1 machine on the X2 that will now "bump" a step on every full rotation unless I get a 'MARK_FUN' error come up on startup.
Can't be bothered re-installing yet I'll do it when my 25LV is built.

If I progress in this line of work then I'll step up to something more industrial.

[CL_MotoTech]

I've been running W7 with Mach 3 for something like four years now.

I very rarely have issues at this point, admittedly there were some trying times in the early usage of the software. Occasionally if I notice something I don't like I will do a restart of the software. Almost all of the issues I have are in initial setup phases, basically during setting of work offsets, never during running. I have a couple of programs that run for 3 plus hours and it runs without issue time and time again.

Maybe I got lucky, maybe I was a little more particular with my hardware/software setup, but I really don't see what the fuss is all about. Mach 3 is pretty damn reliable. I will say that in my slow migration to UCCNC (updates are good) it does a lot of things better. But it's nice to have both options. I run Fusion, listen to music, send emails, all on the controller while it runs parts. This is fine with both Mach and UCCNC. It's never caused even a single issue. Hell, I even keep my programs on a NAS that my controller is connected to via wifi and that's never been an issue.

I would not want to try this on W10 though, it would probably restart itself in the middle of a part.

[wmgeorge]

The secret to using Mach3 is not trying to use a parallel port . I have it on a Warp9 ESS and wires shielded, everything grounded and its as stable as a rock. The other secret do not use Chinese knock off junk when building your CNC. It runs fine on Windows 7 Pro 64, you just need to know how to set up a computer for CNC and not gaming or surfing. Yes both my shop computers are Windows 7 and both are Lenovo laptops.

[dazp1976]

The secret to using Mach3 is not trying to use a parallel port . I have it on a Warp9 ESS and wires shielded, everything grounded and its as stable as a rock. The other secret do not use Chinese knock off junk when building your CNC. It runs fine on Windows 7 Pro 64, you just need to know how to set up a computer for CNC and not gaming or surfing. Yes both my shop computers are Windows 7 and both are Lenovo laptops.

ESS will be the first upgrade at some point. Using parallel port is the problem
Then I'd use my knock off boards for an eventual tool changer.

[hackish]

ESS will be the first upgrade at some point. Using parallel port is the problem
Then I'd use my knock off boards for an eventual tool changer.

I guess a fair way to describe it is that it might work on os software from 18 years ago, but not printer technology from the same era.

The reason I prefer acorn is that it is single source and all supported. If mach 3 crashes, my experience has been that the control board manufacturer gets blamed. The api/plugin technology is so fragile that a driver bug can bring the entire system to a crash.

Maybe I don't have patience for poorly designed things, but I expect a product to work properly when you pay for it.