Mini Model D and questions

[grumpygeek]

Hi All,

I have just about finished a Mini Model D. I scaled down to 24 x 36 inches due to space constraints and the fact that I was using parts I had purchased for a different design.

I would like ask a few questions, please forgive the rambling run on sentences that my follow, it takes me too much effort to write 'correctly'

The drive system is comprised of the following:

5/16 18 tpi lead screws
pacific scientific motors rate at about ~118oz
24v 6a power supply,
xylotex 3 axis and probotix side step (1 axis) using 1/4 steps
All driven by EMC2.

My max speed at the moment is 24 ipm, I am pretty happy with this, does this sound about right for a max speed?

I have cut a few parts out of 3/4 inch MDF using rotozip bits, they come out a bit rough, I figure this is probably the bit. Any recommendations of how fast and deep I should run for a rotozip bit?

Also, I am getting some noise from the screws while running, I would like to apply some sort of lubrication, but I am not sure what to use. I used the nylon wingnut approach, except I used 2 per slide instead of one, adjusted so they still spin easily but there is virtually no backlash (not sure how long this will last). I have graphite, but I have read a few messages that state this is not appropriate, and that beeswax would do the trick. Any suggestions?

I am pretty excited about getting the machine running smoothly, and I am amazed it is working this well. Any help or guidance you guys could give me would be greatly appreciated.

Thanks,
Don Bailey

(Sorry if you are seeing this again, I cross-posted this to the Rockcliff Site Fourm)