Timing Pulley size & Dimensions

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Charley Davidson

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I'm gonna make my pulleys tomorrow hopefully for my cnc plasma table. I need to know what size I should use like XL, L ,H?

I also need the dimensions for the tooth profile so I can grind a cutter for this job. Not sure if I'll do it with a fly cutter or a regular cutter yet.

I need to make several about 3" dia. no bigger though.
 
I'm using L x 1/2" wide for the drive belts and the reduction belts on the one I built Charley. Are you doing a gear reduction? The econobelt link has fantastic prices on pulleys. You might not want to be bothered making them. I bought mine and bored them out and put keyways and setscrews on them.

Here's a couple of good sites for info: http://shop.polybelt.com/main.sc Lots of info

http://catalog.bbman.com/db/domains/static/bbman/config.html reduction calculator

http://www.econobelt.com/ best prices I've seen.
 
I think I'm going 3 to 1 I guess 1" on the motor and 3" on the transfer shaft & drive, sound right? Or can I go with 1" motor & transfer shaft? On my Z one to one, My Y is a self contained linear tracking mechanism.

This is a drawing of how my drive system is setup

Plasma table rdive.jpg
 
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I don't remember all the details Charley. If you want to read thru my build log over at the Longevity forum and cnczone here:http://[URL=http://s1124.photobucke...3abe3ea.jpg.html][ATTACH=full]163369[/ATTACH][/URL] and here http://www.cnczone.com/forums/plasm...numeric-control_plasma_table_build_xalky.html

Using the pulley teeth as your reduction ratio is easier to nail down your ratio, rather than going with a set diameter. Most of my stuff is documented In those 2 places. I went with a 4 to 1 belt reduction, because I wanted the ability to change direction quickly to cut thin stuff. My gantry weighs roughly 90lbs. The weight of your gantry is gonna determine how fast it can change direction. With the small pulley your going to have to make an idler so as to wrap as much belt around it as possible to avoid belt slippage. You can see those details in my build logs.

Marcel

20131116_104855_zps93abe3ea.jpg
 
So unless you or anybody else sees a good reason that this won't work this is the way I'm going, I may change the sprocket size but I think everything else looks good.

Plasma table drive.jpg
 
Sounds like you got it figured out.

Without table specifics, I can't make any recommendations.

Marcel
 
Pictures, gantry weight, what kind of motors, rack or something else, etc. Didn't you have a build thread somewhere?

Sent from my SPH-L710 using Tapatalk
 
Ok... I remembered where i saw your build log and went to take a look at it. http://forum.longevity-inc.com/showthread.php?3556-Charley-s-CNC-Plasma-Table-Build/page5 Your gantry seems to be pretty light, which is good, except for that Z axis. It looks like you're gonna have 2 drive motors on the gantry, thats good! Your steppers are the same size as mine 640oz/in, thats good! I would go for a 4 to 1 ratio belt reduction. For the most part your table is gonna be very similar to mine. Take a look at how I set up the belts. If you need specific pulley diameters, I can get you those. I had a lot of help from Tom over at CandCNC, he made the reccomendations and it worked out really well. It looks like your gonna use a belt drive for the gantry travel, so you can pretty much copy what I did and I guarantee your table is gonna be badass. The only thing I would change on mine is the Z screw is a bit too fast at 1tpi on the screw. If i were to do it again, and I might change it eventually, The Z should be around 5-6 TPI to allow for more reaction time of the THC. Mines a bit too fast and it overshoots the mark a little. I managed to dial it in acceptably with The THC delay.
 
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