Drive ratio question for new build

[Kentuckyfarmer]

If I use 5 tooth per inch timing belts instead of rack and gear for table drive what is the ideal final drive ratio? My table will be used for plasms and oxy fuel cutting. Using blade runner w 620 oz motors.
My way of seeing it is a 15 tooth engageing the belt means every 1 turn moves table 3 inch's. So a 3:1 at the motor is equal to a direct drive.
6:1 at motor is a 2:1 final ratio. If anyone who has used belts or chain, instead of gear rack can shed some light on this it would be a big help, I'am drawing a blank.For what it's worth 10 tooth pulleys are the smallest I can find.

[Al_The_Man]

If I use 5 tooth per inch timing belts instead of rack and gear for table drive what is the ideal final drive ratio?

Unfortunately the question is equivalent to how long is a piece of string!
It all depends on whether stepper or servo, what the mechanics weight-loading, motor size, rapids required.
If you already have the motors, then this will be a starting point, for servo's, I base the reduction on as high as practically possible based on running the motor at just under the max rpm of the motor that will also give the required rapids.
Planetary gear box is one compact high ratio solution.
Al.

[Kentuckyfarmer]

The table will use stepper motor,s 2 for gantry drive, 600 oz that come with the blade runner kit. Sadly it is 3 to 4 weeks out before delivery. Trying to get a handle on the little things befor time to order parts.
Thanks Mike

[Down&Dirty]

My new plasma table runs a 14 tooth gear on the stepper and to drive the belt. It has a 44 tooth for reduction. I am just a little under 1 rev per inch on a .2 pitch belt. Depending on what resolution you want in your parts this may work ok. Initially I had planned on being able to toss in my torch for thicker parts. The thing keeping me from doing it is the timing belts. A torch puts off a ton more heat and those belts are just not up to the task. Make sure that you get the belts out of the way so the torch doesn't heat them up. This could lead to a lot of stretch and possibly failure.

[Arthurmetal]

Attached is a picture of how I made my driving system with .2 pitch (.4 inch width, 8 foot long) driving belt. X-axis is 8' , direct drive with a 22 teeth pulley.
Due to vibration resulting from strech in the belt and too light weigth gantry my cuttingspeed is limited to about 100 inch/min (paticular rough cuttingedge when making right agles and such).
The table still serves me well but my next build will have rack and pineon.
Arthur

[Kentuckyfarmer]

Thanks for the input. Since I first posted this I have found affordable rack from standard steel so I am going with it. I had thought of the heat issue with oxy fuel and timing belts. Thanks

[Kentuckyfarmer]

When I started planning my table I had planned on useing a miller 1500 spectrum that I allready had. After doing research I have found the HF starts in some cases may not work withall the electronics close by, Tom at CandC says with proper grounding it will be ok.
Now for the question the Farm Machinery Show will start in Louis. Ky Wed, a local hypertherm dealer priced me a powermax 65 for just under 2300 $. Is this a good price I really had not been in the market for one so have not checked prices. The spcial only runs thru this sat. Or until supply is gone.
The deals they have at the show are supposed to be the best they offer in this area, hypertherm has reps and a trailer with demo units set up.
This wont come around again till 2012.
BTW if Jim Colt is reading will they upgrade the 65 about a week ? There is nothing worse to be the guy that bought a 8 trac player a week before cassetes came out LOL.
Thanks in advance
Mike