Definately a scrapyard challenge

[Jonathan]

He is using an MDF box

So was I, and I am now though it's no longer there for strength. To start with that will be a limiting factor, but there's always the option to add a steel frame ... or even a simple rectangle on the bed made from steel box would help a lot.

you need to stop pressing everyone with the need for speed? shake rattle and role will not bode well here.

That's why I mentioned you'll get better *acceleration* with 10mm pitch screws, and less vibration from the screw as it's not spinning so fast. I agree high rapid speeds are pretty much useless, but good acceleration is important. When I cut the mayan calender using lower aceleration values (as I was limited by the computer) than Jazz did added over an hour to the time it took. That's quite an extreme example admittedly, but the general trend is true.

Yes they will work fine, but not as well as could have been.