Timing belt and pulleys

[samakthachai]

Hi All,
I am thinking to build laser and plasma machine. Who can advise me for timing belt and pulleys website. If this price is cheap,it's very good.

My spec:
Belt: T5 or T10,
Opened end,
Lenght=3.5 metres ( need 3 pcs.)
Belt width = 1inch
*****************************
Pulley: match with belt.(need 8 pcs)



Cheers,
Samak

[lamicron]

Belts are not good for plasma, too much dirt and metal dust, try gear racks and spurs, Standard Steel Specialty Pitch 20 , , the gear rack 75" length x $24, the 20T spurs$14 each at Mc master carr.

[Pete Stenabaugh]

Timing belts will work fine as they are pretty much maintenance free. If you use rack and pinion, you still need to keep the gear teeth clean. Belts as well also need protection from dirt etc, but they are more forgiving if they get some dirt on them.

For cheap pulleys and endless belts, go to www.econobelt.com. Their pulleys are down in the $10 range, depending of course on size. They do not have open ended belts though.

For open ended belts, you can try: http://www.gatesmectrol.com/mectrol/...cation_id=4976
Another location for belts is: http://www.polytechdesign.com/

Pete

[MonoNeuron]

Stock Drive products (SDP/SI) now have a web site with online sales and sell lots of different types of pulleys and belts. Open ended as well. I like belts as they are very forgiving but you still need to keep the crap out. Just make sure the belts are lower than the table with a cover over them from direct spatter.

Unfortunately McMaster Carr do not sell to overseas people unless it is a big order. They changed about 2 years ago as the paper work was too much for them.
Rich.

[Pete Stenabaugh]

In any case, if you can help it you DO NOT want the belt or other drive system below the table. This is the worst place, as all the sparks, and debris are blown downward below the table. keep your drive system above the table, it is cleaner and much easier to maintain and keep the crap out of it.

I am in the process of designing a new cnc router for my shop. This system will have the drive components above the table, and I am using timing belts for the X and Y and a ball screw for the Z. This design could easily be adapted for use as a plasma machine merely by some redesign of the table support system. On this system the belt drive on the X axis is mostly covered and protected, so for the router, I will have no issues at all, and for a plasma, it would also work just great.

If anyone is interested, I can make plans sets available once I am finished. They are all drawn in 3D in Solidworks and will be available in .pdf format. I just dont know for sure when I can get them finished, but it will be a few weeks yet.

This router plan is going to be commercial quality, built using extruded structure aluminum members for the basic frame (like 80/20 or similar materials), but can be built by anyone with access to a machine shop, and some mig or tig welding equipment. It features servo drive motors for the drives and rapid speeds will easily exceed 400 ipm if you so desired, but I dont know why you need anything faster. The table cutting surface will also be able to be moved up and down to accomodate large items, and the cutting area will be 49" x 97" x 11". The table will be approximately 5' x 10' floor size.

Let me know if anyone is interested......

Pete

[Mongkol]

Hello Pete,
I am interested in your table design. Is it possible to share your idea and concept? I have some questions.
1) If I use timing belt, Does it have accuracy and precision? What type timing-belt do you use? example T5,T10,AT5,AT10.Pls advise.
2) What motor do you use? Stepping motor or Servo.

If I have belt cover, I think it can protect dust or dirty partical. Do you have any comment?


I am thinking to build Plasma machine same as Samak.

Thank you Pete,
Mongkol

[MonoNeuron]

Hi Pete. I didn't mean way below the table in the path of the sparks etc but just below the table height on the side of the machine and inside "C" section so it is away from sparks. I am in favor of a relatively flat machine table top for those awkward jobs that need to be cut once in a while and parts of it need to hang over the edge of the table. Each design has its limitations, I know, but I would just prefer it that way myself.
Hi Monkol,
The timing belt only transfers the precision of the motor to the axis. It doesn't have much to do with tooth count or width etc as the precision comes from your encoder or your 1/10th step stepper motor. If you have a long table with a fair amount of weight to move then you obviously need a wide belt with strong teeth but if you need to move a very small weight around a very small surface with small pulleys, then you need a thin belt with more teeth per inch so they have more teeth in contact with a small dia pulley.
I have had no problems at all with stepper motor drives and they are very easy to set up. A lot of other people swear by servos but they are a bit more expensive and if you use brushed ones then you will be up for maintenance. Not much maintenance with a stepper system and it is much cheaper and just as accurate depending on how you gear your motors.
Hope to be of some help.
Rich.

[Pete Stenabaugh]

My design incorporates a table surface that is lower than the drive system. This is by design to keep the drive system cleaner. I am using servos for my system as I already have the drivers and the motors. This means though that I have to have a double reduction on the drive to keep the motor speed up a bit, however the system could be built using steppers, it is a bit simpler that way.

I am planning on using T5 timing belts, open ended so that the belt ends are clamped at the connection point on the gantry. The connection point also serves as the tensioning point for the belt, which can be tightened to about 150 lbs tension. There will be no backlash in this drive system, and the accuracy will be very fine using 10 step drivers from gecko, you will easily get resolution in the range of about .0005" or so, but that depends upon the motor drive reductions. At any rate it will be just fine for woodworking and plasma, much higher than is really needed for most purposes.

If those that are interested would like to email me off forum to my personal email at customdesign@shaw.ca, then I can send you a .pdf file of the frame that is designed so far. I have the gantry pretty much finished as well, although as it started as a welded assembly, with all the motors on it, I need to re-do the design to remove the X drive system, and revamp the Y axis drive to incorporate the timing belts, instead of rack and pinion.

I like the belt drive better because a rack an pinion drive over a distance of 8 feet, has to run really tight and very accurate, inconjunction with the bearing drive that supports the gantry. This means a lot more adjustment and setup, and perhaps a lot of problems. The belt just removes one of the potential hazard items, and makes for less maintenance.

The bearing system is using 'V' rollers with sealed ball bearings, running on heat treated 'V' tracks made by Bishop Wisecarver. This system is also almost maintenance free, and very tolerant of dirt build up as it has the tendency to self clean the track as it moves (not an excuse for no maintenance though). It is also about the fastest drive system capable of travel speeds of up to 10m/sec, way more than we need. This bearing system is used on all 3 axiis.

As I mentioned this system will be commercial quality, but it should only cost you a few grand to build (no total yet) as opposed to maybe $20K or more to buy. It wont be cheap but it sure will be strong and rigid, and capable of doing anything the big systems can that sell for tons more money, and some things they cant.

Want more? - email me......

Pete

[lamicron]

You can use something like this for the long travel gantry, easy to clean and cheap, also take a look at Torchmate, or go to http://www.cnczone.com/forums/plasma_edm_other_similar_machine/ there you can see many plasma table designs.