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View Full Version : 2006 DynaCNC Power supply correction.



MackB
07-29-2014, 08:23 PM
I have an 2006 DynaCNC 4x8 foot CNC table for a router that I purchased New. I had always had problems with it loosing steps on the z axis (acme drive screw type). I could also never run the x/y axis at anything near the “rated” speeds. I had to have it running to make parts, so I just slowed it way down, and it was usable, although it still lost steps on the z axis, and I would have to re-zero after every part. I had several calls in to DynaCNC and Geko, but never got it corrected. (Geko was much more helpful.)

Well many years later one of the Geko motor drives finally went, and I decided to go over everything since I was in there anyway. My table fortunately was early enough to use CandCNC controllers, Geko motor drivers, and the Kelling 640oz steppers. DynaCNC had used a 250VA 24v CT transformer from MPJA surplus, which would give about 33.5vDC unregulated. When I ran the specs for the motors through Geko's website calculations, they recommended a MUCH higher drive voltage of 80vDC for the motors (over the recommended for the geco drives).

I had always thought the transformer seemed small physically, and had even asked Dave Cress about it once when they were still in business. (I worked in industrial controls for 22 years.) He basically told me the transformer was just fine, and I was an idiot for questioning him. Well, maybe not in those words, but that was the message.

Anyhow, I ordered and Antek AN8448 torrid transformer which was 400VA at 48Vac. This gave an unregulated dc voltage of 67.2 volts at up to 8 amps. Basically double of what was the DynaCNC supplied design. I did have to update some of the Capacitors in the unregulated DC supply for the higher voltage. I also updated the programming resistors for proper rating for the Kelling steppers. The only problem is that the new transformer is much bigger than the old one, and I had to mount it to the door instead of the back panel of the control box.

This has been a night and day difference in operation. I have never detected an lost step on any of the axis, and even the Z has been right on the money. I can run the x and y at over 100ipm if I wish which is amazing when I could not reliably run it over about 15ipm before. I have been running with the new supply setup for about two years now and thing are still working very well.

I have seen several of these vintage machines for sale over the years, and just wanted to pass along this update. The basic frame design has been ok, although the x axis could have been stiffer for routing, but has met my needs. If you treat is as a partially assemble kit of parts, and assume you will need to do all of the controllers calculations from scratch it could still be an ok starter machine.

cryptodecals
09-28-2014, 04:39 AM
Hey Mack what Geko motor drivers are in the 6000? I have a 1000 having some problems losing steps as well.

SolarImages
05-01-2015, 08:57 AM
I am very interested in your power upgrades and any others you may suggest I have been givin a dyna cnc 1000 with gecko 320 drivers and 90 Vdc 7.3 amp servo motors. The Z servo buzz's when at rest. The table is 6' by 11' and the I am looking for upgrades my main focus is cutting 3d hardwoods thanks for any help here!