Re: [CAD_CAM_EDM_DRO] Gecko 2xx "Nema 42 modification"???

Driving the knee works well now - although it was a lot of trouble (a
couple of months) of figuring out how to make it work reliably. I had a
lot of help from the alt.machines.cnc folks.

I have fitted a ballscrew on Z and also fitted two 75lb gas springs -
can't find a pic showing the complete knee, but will post one tomorrow.
I also had to fiddle with the gib for the knee so that it wouldn't
vibrate at speed. Because I still have the 2:1 reduction on the knee, I
don't rapid in Z direction faster than 1m per min (39 IPM)I've found
that's plenty fast enough!

Cheers, Peter

Drew Rogge wrote:

> Peter,
>
> I noticed that you're driving the knee for your Z instead of
> the quill. Does this work pretty well? Does the Z have a ballscrew
> or the original ACME? Are you doing anything to try to counterbalance
> the weight of the knee?
>
> Sorry for all the questions.
>
> Thanks,
> Drew
>
> Peter wrote:
>
>>Hey Paul,
>>
>>Hanging out in this chat group is so much more fun than working... If
>>only it paid the bills! Thank goodness I have all this stuff written in
>>my notebook... Here goes,
>>
>>I selected a toroidal transformer rated at 45V, 14A (625VA). Bridge
>>rectified, with a 12,000uF Cap, this yields ~65VDC. The make of the
>>transformer is Plitron - made here in Toronto, but I purchased it thru a
>>local distributor.
>>
>>The connectors are AMP (now Tyco Electronics) Circular Plastic
>>Connectors (CPC's) Series 1 purchased online from Digikey. The CPC's
>>are cheap with each piece a couple of $. The crimp tool is VERY
>>expensive but is needed to do a good job of the crimp terminations.
>>(Solder tab version pins may be better for small qty's)
>>
>>The motors are Sanyo Denki Model 103H89222-5241 (Mendonet P/N
>>426-1870-SB) 1,869oz-in, 6 Amp, 2.70 Volts 0.45 Ohms, 5.40 Mh,
>>6.43" Length Motor website http://www.mendonet.com/steppers/nema42.htm
>>shows torque/speed curve. I purchased the Geckos and the motors all at
>>the same time, from Mendonet.
>>
>>I use shielded cables everywhere, with shield grounding done only at the
>>Gecko box end. All cables are 18G multistrand with aluminum foil
>>shielding and cost approx. $1 per meter. It's not super flexible cable
>>or anything exotic. Before I learned about the Gecko step rate
>>multiplier board problem I had assumed motor noise was getting into my
>>step signals so I even replaced the cables inside the box (after the
>>photo was taken) with sheilded cable but I don't think that was
>>necessary as the problem remained.
>>
>>Now, back to work...
>>
>>Cheers, Peter
>>
>>
>