[louieatienza]

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when building small size machine, ball screw is good because ball screw is short and machine bed is not bend. But when building big size machine,like more than 2800mm of lengh. machine will be bend. So we will choose rack and pinion. As we know, rack and pinion has gap and accuracy is lower than ball screw.
To keep high accuracy, we must choose ball screw. To keep high speed in big machine, we must choose rack and pinion. On the hand, if using stepper motor, it max speed is 800RPM, can we choose it to build big machine with ball screw and speed is up to 20mm/min? if don't know pulse equivalency, how to choose drive and reducer? it's clue.

If you're really concerned about backlash in a high-speed r&p, why not a helicak rack and pinion, with either a split-or dual-pinion (to eliminate backlash)?

[DHSYCNC]

If you're really concerned about backlash in a high-speed r&p, why not a helicak rack and pinion, with either a split-or dual-pinion (to eliminate backlash)?

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thanks a lot. we're going to choose helicak rack and pinion.

[DHSYCNC]

If you're really concerned about backlash in a high-speed r&p, why not a helicak rack and pinion, with either a split-or dual-pinion (to eliminate backlash)?

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we want to choose control system to compensate it. It's simple and easy. If not get good result, we have to choose above rack.

[ivojnob]

Torsion box started...

[ivojnob]

Finally got around to picking up some 5' x 12' sheets of 3/4" MDF (they were out of 5' x 10'). Cut all of the internal and external strips for the torsion box and dry fit the internal framework. I chose to do half lap joints on the parts as shown in one of my first posts. The fit up is very good. Next on the list is getting the bottom torsion box skin set up nice and level so that I can start the final assembly of the box.

[louieatienza]

Finally got around to picking up some 5' x 12' sheets of 3/4" MDF (they were out of 5' x 10'). Cut all of the internal and external strips for the torsion box and dry fit the internal framework. I chose to do half lap joints on the parts as shown in one of my first posts. The fit up is very good. Next on the list is getting the bottom torsion box skin set up nice and level so that I can start the final assembly of the box.

That's looking great! The 5x 12 sheets must've weighed a ton!

BTW I take you're a bon jovi fan? (I'm a big Jumble player...)