[deanc500]

Hi, Just uploaded a few more photos of the router table we built for
Plastics Plus. Shows an example of how timing belts can be used for X
and Y. In the current configuration, maximum rapid travel speed is
480ipm. Plenty of torque as well.

http://www.axxustech.com/Axxus4x8/axxus_4x8.htm

[HomeCNC]

I posted a picture of this style of movement along time ago. I'm glad to see it in operation.

How does a laser level work to help you keep things flat and true while welding the frame?

[tsalaf]

Dean, interesting design.

What kind of repeatable accuracy are you getting with the belt drive?
Did you source the belt and V groove components in Canada?

Steve
www.tac-pro.com

[deanc500]

Jeff: I made the two sides of the frame first. They are the two pieces that look like bridge trusses. Then I had to insure they were perfectly aligned with each other before welding them together with the three cross members. A rotating laser in the center of the table gave me a reference line to make sure the two trusses were not skewed. I suppose I could have used a regular level, but the laser sure made it easy.

Steve: Resolution is .0005". That was plenty for the plastic pieces that the machine is used for. Linear rails and vee bearing were shipped direct from Bishop Weiscarver. The 10 ft shipping box only weighed 40 pounds, but because of the length, it had to come by truck freight. It cost a small fortune to get it here.

[turmite]

Dean how wide is the belt?

turmite

[deanc500]

25mm

[thielert]

Any stretch?

What kind of load will the belts take? Could you cut 1/4" AL with the machine holding that half thousandth?

What is the gear down ratio from servo to belt pinion?

Tim

[deanc500]

Hi Tim,
The belt is a Gates long length #LL5MR25 Powergrip GT with fiberglass tensile member. The rated allowable working tension (Ta) is 253lbs, but they dont give a spec on ultimate tensile strength. Cant comment on cutting 1/4" AL because we've never tried it. The Belts have been under significant tension for over 3 months now without any sign of stretching or loss of calibration.

The reduction is 9:1 from the motor to the "pinion". The pinion is gates part #P18-5MGT-25 PB. The pitch diameter is 1.128" and it has 18 teeth.

[steveald]

Hi Dean,

Nice design! I have been working on a similar design with the belt above the table rather than below, which allows the "pinion" pulleys to both be mounted on a common shaft running through the gantry.
How did you manage to get 9:1 reduction? It looks like 18 tooth to 54 tooth would work, but I can't find any 54 tooth pulleys.

Thanks,
Steve Aldridge

[deanc500]

Hi Steve, yes I used a common shaft through the gantry as well, but it is connected directly to the motor. Then there is a 9:1 reduction on each side of the gantry from the common shaft to the pinions so the pinions are turning 9 times slower than the motor. The pinions themselves are not involved in the reduction. They only provide the traction for linear motion at a rate of 3.542 inches per revolution.

[Mr.Chips]

Dean,
Good looking machine.
I’m designing a stepper controlled machine about 28” X 36”. I really like your belt drive system, do you think it would work on a stepper driven machine that would be cutting aluminum occasionally?
What would the negative aspects of a belt vs a lead screw machine?
Thanks
Hager

[barbwirebi]

Hi Dean

Great Design
Do you sell any of your plans or "Bill of materials" or info?
I want to use the belt concept and the Vee bearings in my design.

Thanks
Bill

[Splint]

I must say I like the idea of belt drives. Is anyone else here using a system like this? After using it for a while is it still your prefered method over ball screws? Any other comments?
Splint

[Sergey]

Hi
I found this link with timing belts drive mashines
http://cnc25.free.fr/machinescnc25.htm

[tpworks]

I aquired some 3/4" (19mm) wide belts with 20 steel cord reinforcing that I plan to incorporate in my next design. pretty much along the line of Deans machine. Nice job.

[ESjaavik]

DeanC500: Very nice! What's your experience with the gearing? It seems to me that you will get appx 10mm/rev and with that motor it should translate to around 65Kg! pull at the Y-axis. Did you experiment with this to optimize acceleration and speed?

[cutfinger]

I am using belt drive on the long axis of a machine I built and use commercially. I chose to use a stepper motor with a driver set to 5,000 steps/rev which negates the need for building reduction gearing and the backlash it can introduce even if carefully made.
I am getting blinding fast G00's and smooth G01's. The resolution is .0008 which is fine enough for what I am doing but can easily be reduced with a smaller timing pully on the stepper shaft.
Photo quality printers, I believe, all work with steppers and belts and there is nothing more demanding than a high quality colour print.
I am an unashamed stepper man and have found that if you use them within their range they do not make mistakes. Microstepping is the key.

[cutfinger]

I am using belt drive on the long axis of a machine I built and use commercially. I chose to use a stepper motor with a driver set to 5,000 steps/rev which negates the need for building reduction gearing and the backlash it can introduce even if carefully made.
I am getting blinding fast G00's and smooth G01's. The resolution is .0008 which is fine enough for what I am doing but can easily be reduced with a smaller timing pully on the stepper shaft.
Photo quality printers, I believe, all work with steppers and belts and there is nothing more demanding than a high quality colour print.
I am an unashamed stepper man and have found that if you use them within their range they do not make mistakes. Microstepping is the key.

[deanc500]

Hello, the machine was very easy to setup and calibrate. It has a maximum speed of 430ipm on the x and y. Small repeatable movements of .0002". There is no backlash. The system has performed flawlessly since it was installed nearly a year ago. Belts have stayed taught and I haven't had to tension them yet. I would definitely use belts again over lead screws. I have also seen good results with rack and pinion. The Trumpf CNC lasers I work on are worth over a million dollars each and they use rack and pinion. The machines have to be meticulously leveled and also be very rigid, then the pinions adjusted to get rid of any backlash. Rapids on those machines are 8000ipm on x or y and 12000ipm diagonally. Z axes are were generally gear reduction driving a belt, but recently they have gone to linear motors on Y and Z (Y is across the gantry and X is the long axis). I am planning to build a plasma table this summer designed after the Trumpf machines. I am aiming for rapids over 2000ipm (why? just cause I can) so I will have to use belts or rack, and huge high torque motors with little gearing.

[cutfinger]

Why is everyone so taken up with rapid moves, how fast does one really need to go?
Just using an unfashionable stepper motor with a timing belt driven directly off the shaft my cutter spindle has returned the 5ft home long before it has stopped rotating. I have a mechanical brake on the spindle so I can increase output!
I am cutting at 100 inches/min which is what works for my application - I could go much faster.
It is all about applications and personal preferences to what works but it does seem that steppers have got a bad wrap because they cannot cut the air as fast as servos'