Where I can buy pinions and a 120" rack online?

[kanankeban]

Hi,
I need to get a 120" rack to drive my x axis, does someone knows where I can get this online, or the way to put together two smaller racks forming a 120" inch one...
Regards...
Hector

[trubleshtr]

try McMaster Carr's web site, or Misumi's web site.....both sell lots of industrial stuff at average cost.

[ger21]

Use a 3rd rack teeth to teeth to align 2 together.

[kanankeban]

Originally posted by ger21 Use a 3rd rack teeth to teeth to align 2 together.

Hi,
Could you explain how this is done...and is this a common procedure in the big Brand CNC Router Tables
Regards...
Hector

[turmite]

Hector, did you say 120 inches for your z axis? You must be building huge machine, maybe for foam carving??

Mike

[duluthboat]

You can use a short section of the same rack to get the correct alignment of many short ones to make a longer one, as ger21 has said. High end pro machines seldom use racks. Here is a quick example of what it would look like. The gap is over done for effect.

Gary

[ynneb]

Hecktor, Just for your reference, you could use timing belt instead. The belt is fixed at both ends of the machine and loops over a drive pulley. I have used this method, and an very happy with its performance.
I must admit, it doesnt sound that great, but I am so happy with it, that I will be using it on my next machine as well.

If you need more details let me know.

[kanankeban]

Originally posted by turmite Hector, did you say 120 inches for your z axis? You must be building huge machine, maybe for foam carving?? Mike

nop I mean 120" for my x axis....

Regards...
Hector

[kanankeban]

Originally posted by ynneb Hecktor, Just for your reference, you could use timing belt instead. The belt is fixed at both ends of the machine and loops over a drive pulley. I have used this method, and an very happy with its performance. I must admit, it doesnt sound that great, but I am so happy with it, that I will be using it on my next machine as well. If you need more details let me know.

It will be great to see how the timing belt concept is done...If you have some pictures it will be great.
Is this method more expensive than the rack and pinion option?

Regards...
Hector

[kanankeban]

Originally posted by duluthboat You can use a short section of the same rack to get the correct alignment of many short ones to make a longer one, as ger21 has said. High end pro machines seldom use racks. Here is a quick example of what it would look like. The gap is over done for effect. Gary

Now I got it Thanks so much...duluthboat

[turmite]

Originally posted by kanankeban nop I mean 120" for my x axis.... Regards... Hector

Now I'm embarrassed! It's been along day.
Mike

[ynneb]

Hecktor I downloaded these pics off a web site a long time ago, and dont know where to now point you. Here are two of the pics anyway.


This next picture also shows a V bearing in the setup. There will be another Vbearing abouve it that is out of site. You will need 8 V bearings per axis. That is 24 bearing for a 3 axis machine. More than you would expect hey?


The only reason I am including my interpretation, is to demonstrate that such a system can be done without special milling tools. I just used a drill to do this system.


Yet another image.


Belt clamps

Instead of buy the belt clamps I cut a piece of angle iron into a 1 inch length and attached a plate to it with 4 bolts. I had no groves in it but tightened the buggery out of it so that it squeezed the belt between it. ( It has not moved one bit ) on the other angle of the iron I put a hole and bolt through it and attached it to the frame. This way I could always tension the belt.

I am so convinced with timing belt. While the belt was sort of slack I tightened the bolt about half a turn and it tensioned up to like a guitar string. This demonstrates that there is un measureable stretch in it. The belts I have got, have steel wires embedded in them.