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Hey fellas, a quick question. My CNC is a 1999 model Precix with servo drives running timing belts for the x and the y. The z is ball screw. It also runs on Precix software. What would it take to switch the x and the y over to rack and pinon and to a different software? Precix offers to do this with their software (my table is 4 x 4) for about $4500. Can I do this for less money?

Thanks
Shane

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Canada

Hi Shane,

It can certainly be done for cheaper but what's not known is if it will be as good as their in house upgrade.

To upgrade, you'll need R&P Hardware, Drives and Motors, Computer interface, Control software.

R&P Hardware: CNC router parts sells R&P systems for hobbyists here: http://www.cncrouterparts.com/pro-rack- ... i6gqt0vq66 This system would run you about $600 -is. I'm sure there's other systems out there but I'm not really in the market so don't really know anything about them. My gut is that the R&P system supplied by Percix would be of higher quality.

Drives and Motors: This will be the big expense if you can't re-cycle your existing drives and motors. Most affordable controllers use step and direction to control the motors so if your machine has standard types of drives that accept this signal you might be ok. There's basically two types of servo drive systems, those that close the feedback loop at the driver and those that close the loop at the control software. If your drives close the loop for you, there's more flexibility in control software (e.g. Mach 3). If they don't, you'll need to choose controller software/hardware combo that can close the loop for you (e.g. Kmotion Kflop)

If you can't re-cycle your drives and motors, you're talking about maybe $600 for a decent 4-axis stepper system: http://www.automationtechnologiesinc.co ... 8v7-3a-psu . If you go with servos, they have this new low cost setup here: http://www.automationtechnologiesinc.co ... cko-driver for just over $1000 but servos go up from there depending on quality. If you go with some other setup expect to pay anywhere from $500 to $1500 per axis (remember you'll need 2 drives for your gantry axis). There is also the possibility that you can at least recycle your motors if not the drives.

Most home made systems run from a PC so you'll need an interface between the PC and your driver system. These are usually pretty cheap, running from $50 to a simple break out board to $250 for a Kmotion Kflop which is also a motion controller and can close the loop for your servos. I would recommend at least going with a USB type of interface for the motion control like smooth stepper for Mach 3 or Kflop with either Mach3 or their own control software, KmotionCNC.

Software: Most home guys are using Mach 3 which has the advantage of price ($150), a huge feature set and a very large support community. The down side is that the software is only ok and it can give you troubles. I've been using it for a few years but I've uncovered a lot of issues with it, especially if you're pushing your machine.

I've heard a lot of good things about eh Kmotion system but you'll have to customize the software yourself by modifying/writing C routines. When I finally can't take Mach 3 anymore there's a good chance that this is the rout I'll be taking. As a guess, I'd expect that the Percix software is better than Mach 3, that Percix and Kmotion are probably about equal in terms of functionality but that Percix will be easier to use than Kmotion.

So to summarize, yes you can do it for a lot less than $4500 with the biggest savings being in the motors and drives. If you can re-cycle your drives and motors, you can probably do it for under $1k using the CNCRP hardware + new controller. If you need new drives, you're talking about around $1600 for a stepper based upgrade to $2200 for the cheapest servo based upgrade.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Shane call me tonight about 10pm central time. I am still having fits with my rack and pinion after something went slowly wrong that I did not catch for a while and now I am about to pull my hair out, well, if I had hair!

Is your 4X4 table a moving table or fixed? If fixed, consider ball screws for both the x and y axis, keep the servos you have and upgrade your controller. If your table is a mover, that means you gotta have an 8ft ball screw........ .

I personally would love to have ball screws on my machine, but the y axis is 144" long!

Mike

The ballscrew only needs to be the length of the movement, it's the rails that need to be the length of the table plus the length of movement.

It takes a lot more know-how, but you can retrofit more or less any machine directly with a KFLOP if you can figure out how to interface it to the drives. That'll set you back $500 including the KANALOG add-on board. Interfacing is the rub; both times I've done it, I've had the help of a friend who's rather than expert at reverse engineering electronics.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Bob you are of course correct on the ball screw length .

I wish I could find someone who really knows steppers!

Mike

I use the R&P hardware form CNC Router parts on my 4'x8' router and it works well. The newer version is supposed to be even better. If you are just building guitars with it i don't see why you would need anything better, but it's probably a lot more trouble to install the CNC Router parts R&P system on your machine since it is setup to be installed on 80/20 extrusions.


Dan