Building a waterjet gantry

[AKFALAR]

We have a 6'x10' cutting envelope waterjet however its belt driven.

I want to do a ball screw retrofit. Basically im building a new gantry. I will need to buy bearings ball screw etc. Im not dense on these items however i lack judgement on specifications.

I will be using good linear bearings IKO etc. and thats about as specific as i can get. This thing needs to be precise @ .3 to 40 In/min travel speeds. THis is relatively slow and the waterjet tool does not play a large role.

The gantry is about 2-300 lbs so it is heavy enough to counteract the force of the waterjet.

My question is: do 3/4"dia. ball screws (2) work for the 7' axis? and 1" for the 11' axis.

at these travels where should i go with the pitch?

Any comments appreciated.

AKFALAR

[lgreeves]

Did you consider a rack drive system?

[Zumba]

At those speeds, you should have no problems. Use 1" screws for both axes. Keep rapids around 50ipm. 1" x .250" lead should be fine. Use anti-backlash nuts.

[AKFALAR]

I was looking at the Super Dooper rack system NEXEN.

I am worried about rack systems beceause of backlash and reliablility.

So 1" would work @ 11' ?


thanks for the comments

[Zumba]

IIRC Nexen products are bloody expensive.

Yes, 1" will work at 11' with a critical speed of about 250 RPM, with the standard fixed-simple bearing supports (dual angular contacts on one side, radial on the other).

[AKFALAR]

Would Roton be a good choice?

Its the only place with pricing.

Thanks

[NC_jimbo]

I guess I'll ask the obvious....

Isn't a machine like this worth 100K$+ and worth a lot of $/hr?
Sems like you'd want a designer that would convert and tune this machine to the max speeds possible for best production rates.
Curous how a DIY solution makes economic sense.

[AKFALAR]

Thats waterjet my friend. The travel speeds are limited by the HP on the pump per given material thickness and type.

Most of our cutting is done @ 20ipm and under. Really 15ipm and under.

Are you talking about traverse speeds?

[ajmoir]

I'm currently building a router table for 8x4 and am planning to use belts.

Why are you swapping from belts to screws?

I'm guessing the 300lb gantry is causing problems on rapids?

[AKFALAR]

Were not that concerned about rapids. Mabye we should be however the gantry is heavy.

The belt to ballscrew switch is based on accuracy and backlash. Belts stretch and gears wear to a point where the lash increases over time.

repeatability is great but cutting circles and stuff is difficult.