Ballscrews or Rack and Pinion?

[ciur]

Hello Guys, several questions regarding your transmision too, I want to use direct shaft on a 4x8 gantry, with double X motorization;

What pitch and gear angle are you using? I was thinking of pitch 24, 14.5º.

What number of teeth are you using on the pinnon? I was thinking of 14-15 teeth.

[Javelin276]

Hi There,
I used 16 pitch 24 tooth pinions, 14.5 deg.

Without a gearbox, I can only use it to move a torch where the torque isn't required. We have a second table under construction where we are using gearboxes, so torque won't be a issue so we can use a router. My motors are frame 34 by the way.
Thor

[ciur]

Thank You Javelin;

I need an extra help, I looked at the page you reccomended www.mcmaster.com, and they have what I need, but I want 8' racks, did you had any experience joining their rack sections?

Anyone that can help me:

I've got another question, do you know the standard pitch and degree on machine torchs, I don't know how to calculate it and just received a new oxy-a victor without any instructions.


Regards
Antonio

[ger21]

Originally Posted by ciur Thank You Javelin; I need an extra help, I looked at the page you reccomended www.mcmaster.com, and they have what I need, but I want 8' racks, did you had any experience joining their rack sections?

Use a spare piece of rack teeth to teeth to line up the joints.

[Al_The_Man]

Originally Posted by ger21 Use a spare piece of rack teeth to teeth to line up the joints.

Also, unless the rack is precision ground at the ends, i.e. if its random cut, the easiest way to trim the ends is to cut off a fraction short of the last valley on each end, this leaves a small gap at the bottom of the valley when mounted, which does not affect the operation due to the gear tooth never bottoming out.
Al.

[Javelin276]

Excellent tips on getting the racks extended. Thanks guys, I need that tip too. I'm building a second table which is about 10 feet long and I hadn't figured that part out yet.

I'm sorry, but I don't know the oxy-acetylene question.
Thor

[ciur]

Hello guys again a question from the newbie, (Havent told you I'm in Mexico, and havent found anyone else that's in a project like these that could help me)

Several questions:

My controller has two internal opto relays, I find risky to turn the plasma on/of with them but I want to do the activation remotely. I know I can slave biger relays to these ones, but I don't know what type of relays to use. Can you help me please.

I'll keep the other questions for another thread.
Regards

[bennett71]

Allen,
Are you looking for speed for repetitive production, or are you looking to do some one off parts. If your machine is going to make you money, you make a lot of it in rapid traverse period. This is the beauty of ball screws, they can handle it in the right enviroment but will get expensive depending on the application. If you are doing some one off parts from time to time, a rack will be cheaper to maintain if you don't punish it. Racks don't seem to stay tight & accurate with high speed linear changes over time with out adjustment where a ball screw will. Tom