[accuratemike]

You use the gear box to give the motor a mechanical advantage over the weight of the axis, right? So an .857 gear dia. has a linear move of 2.750" per motor rev. if hooked direct. Divide that by 4 (4:1 reduction) gives you .687 (call it 5/8")linear move per rotation of the motor. That is actually fast compared to a ballscrew. 1/4 lead on a screw gives you 1/4" linear travel per rotation of motor.

Am I understanding the information correctly?

Thanks again
-Allen

Yes. My own machine uses 4-turn screws. 1/4" per turn. The rack/gear machine moves ~.687" per turn. I am only using 187oz motors to move my 65# gantry 90ipm (425rpm). The rack/gear machine has 916oz motors and made 1750 rpm. I could get it to accellerate to 1200ipm in less than 2", but it was hard to watch without taking cover. We settled on 700ipm in 2". We have been cutting in the 60-90ipm range, 700 ipm rapids are fun to watch though. Good luck, MIKE

[freak_brain]

Thanks for the pics and all the added info. Also thanks to you Mike, both of you have been a big help. I guess I need to go with the rack and pinion...I priced the racks today for a 1/2" wide rack it's around $12 foot, is that about what you guys paid? Thats from boston gear distubutor

-Allen

[Javelin276]

I paid a little less, about $62 for 6 ft from McMaster Carr (www.mcmaster.com) and search for "gear rack".

My table has a 4 ft x 5 ft work area, so the 6 footers worked well on mine if that helps any.

Thor

[Bloy2004]

Thanks for the pics, Javelin. There's a lot to look at in those!

Bloy

[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]

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]

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