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Building my CNC Router.  


The first test.

I was having problems with the stepper speed, or lack of. I found some better stepper drivers and motors at http://www.oceancontrols.com.au/. The new drivers have built in current regulation and a half step option. Once fitted the router started to perform much better.

But I was still having problems. The rout was very rough, any change in timber density ( grain ) made the router tip wobble. I worked out there was too much movement or slop in the gantry, but this was not easy to fix. I was considering abandoning the current design and starting again with some industrial linear bearings and good worm drives. But the cost was scary.

In my research to find a supplier for the parts I needed, I stumbled across http://www.cnczone.com. This site has a forum where members talk about their own router designs and problems. I noticed most of the routers were running spindle speeds of over 15,000 rpm. Hang on, my spindle only had a maximum speed of 3,000 rpm!

So I went out and bought a cheap plunge router. The router has variable speed, 600 watt motor, 2 year warranty and cost a staggering $50. What the hell, it if didnt fix the problem I could use it elseware in the workshop. While I was at it, I bought a small engraving tool.

I made an adapter for the Z axis to take both machines, with the engraver mounted below the router. So when I want to rout I take the engraver off, and visa versa.

Well this made all the difference. The cnc router now has no problems with wobble, and give a nice clean cut. The machine was now usable. So I made a sign for the dog from a bit of old hardwood.

Next in the list of things to do was improve the stepper speed more. My maximum travel speed was only 200mm per minute, a bit on the slow side. To home the machine could take several minutes. Some research hinted that I need a much higher bus voltage, and Terry confirmed this for me.

So I modified a couple of computer AT power supplies. First I isolated the -ve output from ground in one of the supplies. This was then connected to the 12v output on the other power supply, and gave a total voltage of about 24 volts. The output of each powersupply was also "tricked" up to 14volts, giving 28volts total. I crammed the two power supplies into the electronics box and fired it up. What a difference it made, my travel speed was adjusted up to 350mm per minute, now we were moving!

Next I upgraded the PC driving the CNC router. I was using a PII 300MHz machine with 256M ram. I had a AMD 2.4GHz cpu and mainboard doing nothing, so I built a new PC and installed the software. This increased the CNC speed to 400mm per minute, not a big step, but the software ran a lot smoother.



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