View Full Version : Computer for Mach3 (maybe OT)
Following the posts by Mcgyver & Mcona (sic) here on servos, could someone just give me a brief run down of the state of the art in computer processors for a machine to run Mach3.
I have run into problems with my ancient machine (650MHz Pentium 3) as it can't put pulses out fast enough to drive the servos at full speed. With 1800 pulses per motor revolution, the fastest I can get a single motor to spin is 1250rpm, hence a pulse rate of about 37.5kHz (running Mach in 60kHz mode). I can get the motor to spin faster in TurboCNC on a Pentium 2!
I'm aware that a lot of newer motherboards don't have parallel ports, so what is the fastest processor/motherboard combination available that still has a parallel port?
Ideally I'm looking for a list that goes 286, 386, 486, P, PII, PIII, PIV, etc. with a similar list for AMD chips.
I can buy a PIV 3GHz full system for 200GBP, or an Athlon 64 X2 5600 + motherboard (with parallel port) for the same money. Which would the panel suggest?
Or should I invest in a KFlop controller (roughly the same money) and not bother with the PC?
08-21-2010, 02:26 AM
I use an AMD 64 in my mill. Cant remember how fast. In my lathe I have a small CoreDuo based board. Even if your machine does not have a parallel port you can add one with PCI or PCIe. Parallel ports may be disappearing from MB's but they will be available as a card for a long, long time.
And even some of those machines that looks like they dont have a parallel port actually do. Look near the IO area on the board and chances are there is a 26pin header sitting there. Run a 26pin ribbon to a DB25 and you are ready to go. My Core2Duo board is like this.
One thing to check though is do do you have Sherline 1/2 pulse mode on? That will cut your output frequency in half. Also your pulse settings in the motor setup dialog should be 1us.
I have said it before. If I were to do a mill again I would forget about Mach3 and get an older control from Milltronics. That way I have rigid tap and a real control. By the time you finish messing with breakout boards, speed control boards, and all that stuff you are about in the range of a refurbed older control.
08-22-2010, 12:01 PM
The essential thing is to have a computer that does not share main memory with graphics memory. You need to have a graphics card with internal memory. That, combined with following the Mach3 instructions for paring Windows down you can use almost anything. My 1.2 Ghz Celeron will run Mach3 at "full speed".
08-22-2010, 01:26 PM
If you don't mind assembling your own PC from parts (pretty easy, actually) it is quite easy to find a motherboard with a parallel port for pretty much any CPU. I take it there are still a lot of peripherals in service in the field, besides CNC machines, that use it. Rumors of its demise have been exaggerated.
Thanks for the replies.
Does anyone have any thoughts on the KFlop? On paper, it looks good but a search of here, CNCZone and the Mach forums has few results.
Is a specific rigid tapping function necessary if you have a servo-driven spindle? I'd have thought you just flip a switch to change it to a C-axis and do a G01 in C and Z. With ER workholding, the semi-rigid tapping collets look good.
It's good to know a 1.2GHz Celeron will run at full speed. The cheap 3GHz I was looking at will do then - I've also found it cheaper with no peripherals.
Presumably the MB data sheet from the manufacturer is the final word on whether it has onboard parallel support.
08-22-2010, 02:09 PM
I had looked at it a while back when the cncbrain was being talked about. It does have some possibilities but the price added up fast when you started adding modules.
You might look at other options as well:
Couple of the guys here are going to use the Galil. I have a smoothstepper in the tiny sherline lathe I have. It works but support sucks and there is still no backlash comp.
12-22-2010, 02:56 PM
Or emc2. I think price wise - you get a ton more bang for your buck.
you would be able to do rigid tapping without needing a servo for the spindle.
(this was done with just printer port hardware)
but there is hardware out there that will allow interfacing with industry standard +/-10v servos for under $200 that also has high speed encoder counters. (or hardware step generation < $100)
12-24-2010, 02:12 PM
+1 for EMC. It might run fine on your doorstop machine and if not you can build one for circa 200 bucks. Mach still has some edge in user friendliness for the beginner but the gap has closed immensely in the past two years.