belt driven CNC table? (I have pictures)

[rcbamm]

hey guys, I was wondering if it will be good enough to use a belt driven setup for my X rails? I came up with a quick drawing of what I am thinking and how my CNC design will look from the side. My rails are going to be 54" long and to get a ballscrew for that length it's gonna be costly I was checking out the Acme Rods and found some one here in FL that sells them and those arent bad but I heard that they sometimes stall the stepper motors? and aren't as precise. I thought that pretty strong belt with pullys on both ends would be more "precise" and I think it might be cheaper. not sure, was also wonderign if any of ya had some good links on belts and pullys. I found a Robotic website that had a 1" x 90" belt for some thing like $98 and then the pullys are like $15 a peice and I was thinking, that is almost as much as a Ballscrew! but if there are cheaper belts I would check into them.


My drawing.... the belt and Pullys would go directly in the middle of the table and then I will have a support bar connecting the two bearing cars and then I will strap the belt onto that bar and then I will get my back and forward motion.



Note: this is a quick CAD drawing!


-Dan

[Kipper]

I'd be inclined to use 2 belts to prevent the "Y" from skewing... Have a look on fleabay for Carolbrent aka HubbardCNC as that seller lists open ended belts and suitable pulleys (not available to UK buyers...Grrr ) Also consider making a reduction drive using belts/pulleys for as backlash free an installation as possible (on the cheap) Oh and check out the linear slides with skate bearings they sell? hth

[rcbamm]

thanks for the reply but I can't seem to find any information on carolbrent or hubbardcnc got any links?

[Kipper]

Hubbard-cnc-inc Interesting stuff!

[rcbamm]

SWEET! this is exactly what I was looking for! thank you!!

[Kipper]

Originally Posted by rcbamm SWEET! this is exactly what I was looking for! thank you!!

If you buy anything ask why they don't post over the pond lol glad to help

[rcbamm]

pong? lol

[ajmoir]

Originally Posted by rcbamm hey guys, I was wondering if it will be good enough to use a belt driven setup for my X rails? I thought that pretty strong belt with pulleys on both ends would be more "precise" and I think it might be cheaper. not sure, was also wondering if any of ya had some good links on belts and pulleys.

Hi,

I'm building a belt driven xy table, take a look here

I purchased my stuff from EconoBelt as usual I still spent the same but bought better stuff I went for wide L belts and steel pulleys on .5" shafts.

I had some custom brackets made at BigBlueSaw. These are adjustable to get belt tension. Also, my motor shaft doesn't have any lateral load but rather feeds a separate shaft in bearings. Steppers do not like lateral loads.

My take on the belts is that they work at lengths that ball screws cant, they more forgiving of poor tolerances.

My total cost per axis less motors is $200, the cost difference between a 4ft run and a ten ft run is peanuts compared to the pulleys and mounts.

[martinw]

Originally Posted by rcbamm hey guys, I was wondering if it will be good enough to use a belt driven setup for my X rails? -Dan

Dear Dan,

For what it's worth (probably not a lot), I looked into belt drives for a small CNC MDF frame 3 axis router last year. Like other people, a belt drive on both sides of the main bed seemed a good idea.

I came to the conclusion that the stretch of the belts under dynamic loads might be a bit of a problem. This was partly because I found it quite hard to relate manufacturers' figures of belt stretch ( if indeed they gave them) to the forces involved in a machine that accelerates etc.

Kipper is absolutely right, by the way, that open-ended belts are hard to find in the UK. You people on the other "side of the pond" do not know how lucky you are compared to us in "rip-off" Europe.

Best wishes

Martin

[Kipper]

Originally Posted by martinw Dear Dan, For what it's worth (probably not a lot), I looked into belt drives for a small CNC MDF frame 3 axis router last year. Like other people, a belt drive on both sides of the main bed seemed a good idea. I came to the conclusion that the stretch of the belts under dynamic loads might be a bit of a problem. This was partly because I found it quite hard to relate manufacturers' figures of belt stretch ( if indeed they gave them) to the forces involved in a machine that accelerates etc. Kipper is absolutely right, by the way, that open-ended belts are hard to find in the UK. You people on the other "side of the pond" do not know how lucky you are compared to us in "rip-off" Europe. Best wishes Martin

:threadhijack ahead: I found a supplier called Wyko in the UK that can supply me with them Martin....For a price

[martinw]

Originally Posted by Kipper :threadhijack ahead: I found a supplier called Wyko in the UK that can supply me with them Martin....For a price

Dear Kipper,

Thanks for that. I do not wish to sound ungrateful, but the belt stretch stuff could still be an issue. I'm pre-judging it, sorry. Will take a peek really shortly.

Thanks again..

Best wishes

Martin

[Kipper]

If anyone wants to express an opinion (I've been wrong before lol) and I'm actually on topic for once Attached is a rack type system that seems "awfully good" Very generous .zip file size allowed! admin.