Steel Gantry Machine 1500x750x200

[JAZZCNC]

What would be the maximum length of 20mm ballscrew in this application? What would be critical length that needs rotating ballnuts?
Im thinking of getting more distance from gantry travel...

Oh very hard to answer because depends on the end fixing etc but I wouldn't go above 2000mm and at that I would have Both ends with Fixed bearings and slight preload on them. When I build 4x4 size machine I always use Fixed/Fixed end bearings as the slight cost difference is worth the extra support it gives.

[Gary]

To work out the critical speed of a screw there is a calculator on our site.
http://www.zappautomation.co.uk/inde...lculators.html

In the lower part of this page is a link for the calculator.

[njhussey]

I'd brace your ballnut mounts, they just look a little flimsy compared to the rest if it. Looking good!!

[Boyan Silyavski]

Yes, why would you save money from the ball nut housing? They are so cheap and are preferable , cause with coupled with straight plate, there is no need for reinforcing, but as you have done it doesn't look strong.

[JAZZCNC]

Yep just beef up the Ballnut mounts and your set to go.!
One thing I see is that you don't have much room for adjustment or alignment with that threaded bracket setup so give a little thought to how you'll do this for both directions. Ballnut housings tend to be easier to adjust than fastening ballnut direct to plate like that.

Those little white brackets sticking out on the end plates are those for triggering limit switches at each end.? . . . If so have you thought about using a traveling switch and save your self a lot of wiring and messing around with brackets etc. I do all my machines this way and it saves alot of work and easy to setup.

[toomast]

Yep just beef up the Ballnut mounts and your set to go.!
One thing I see is that you don't have much room for adjustment or alignment with that threaded bracket setup so give a little thought to how you'll do this for both directions. Ballnut housings tend to be easier to adjust than fastening ballnut direct to plate like that.

Thanks guys! Improvements implemented.

Those little white brackets sticking out on the end plates are those for triggering limit switches at each end.? . . . If so have you thought about using a traveling switch and save your self a lot of wiring and messing around with brackets etc. I do all my machines this way and it saves alot of work and easy to setup.

Yes these are brackets for limit switches. And I have not thought about using only one traveling switch!
Simple and ingenious - for sure I will also implement this!

I will go ahead and order my stuff from BST Automation.

[Boyan Silyavski]

Thats better.

I believe Dean meant 2 switches per axis, one wired home other wired like limit. With the benefit of all limits and all homes wired together respectively with the exclusion of the A home switch /second long axis/ which has to be wired separately, so you could perform gantry squaring

[Lee Roberts]

Agreed, your work on this looks super sweet, should be a nice solid machine frame, nice one Toomast!

.Me

[toomast]

As I have invested a lot of time and money into this project I don't want to create unnecessary problems with cheap components. I know that lot of people use them and are happy but I don't want to waste any hour or even days for troubleshooting - just to find out the fault was the dirt cheap BOB ;)
Any other recommendations for BOB?

[njhussey]

CSMIO all the way if you want a good one...