Now that's cool. I need to redesign my camera slider to use this method. That way the belt doesn't get caught as easy in transport.

 

Have you had any luck with the belt and pinion example in vertical arrangements?

 

@kram242 I think I am going to revise my approach to using the rack and pinion method, as I have determined that the vertical arrangement, while it may be able to support the given weights, it will be difficult keeping each side in sync with one another due to these weights.

 

@kram242 Would there be any difference in using the 90 degree cast brackets instead of the 90 degree angle corner connector? Although I like the aesthetics of the 90 degree angle corner connector I'm trying to reduce cost in my design.

 

This really works great!!! ... but my belt is disintegrating like crazy! This is just speculation but I believe that the belt is either being pinched or rubbed against the extrusion which is causing considerable wear. Have done any long term tests yet? I've been running mine almost non stop at 20-30mm/min for about 2 or 3 days now and I've noticed marks on my belts with little bits of rubber below the extrusion.

http://imgur.com/a/DGR5u (the photos are too large to upload in thread sorry)

 

Hi all,

First post here!

It's a great design in my opinion and it opens up a lot of doors.
What is the highest speed that can be obtained with this setup?
Can it work for a CNC laser machine that can go as fast as 1000 mm/s with high acceleration/deceleration?

Thanks in advances for your input.

Dee.

 

The motor used would be the one in the main design and the OpenBuilds store, e.g. Nema 17.

Thanks.

 

After looking at your pics I see that the belt is raised out of the V-slot.
If I'm right your problem lies with how your belts are fastened.
By having them raised out of the extrusion it allows for pinching of the belt.
Just my 2 cents try something like I did and I have 0 issues


Hope that helps

 

The only issue I may see with poly belts is stretching under loads.
For lasers and 3D printer it's not an issue for sure

 

you might run a smooth bearing to turn the belt towards the pulley, like the servo belt.
they use a pair on each side, one to pinch the two belts together and the other turn the belt toward the pulley.

 

are you still happy with the V-Slot Belt+Pinion? or would you have used the Linear Actuator (belt drive) setup in hindsight? thanks.

 

As of right now, I am not 100% satisfied with this sort of setup. I still have issues with the belt ripping and I have a higher degree of inaccuracy than I did with my previous setup (gear pulley, cart, idler pulley) I find that I can be anywhere from .5mm off to .9mm off and it's in consistent. Though this is within the tolerance that I expected for my printer at this time, because it's a work in progress. Either way, this still saddens me.

Now that being said, here is a brief synopsis of the observations that I've made since making this setup. Since my initial install, I've "upgraded" to 10mm wide GT2 belts with a ~11mm Dia metal gear pulley and the 'ripping' continues. Robert Hummel suggested that I lower the attachment point of my belt to where it lies within the extrusion in order to stop the rubbing against the extrusion. I have not had the time/money to do this yet but I do not believe that is the problem anymore.

I believe the problem is due to the wheels actually. From what I can tell, the majority of my issue resides in the mismatch of the diameter of the wheels and the diameter of the pulley. The pulley is about 11 mm and the wheels are about 24mm. I haven't done the math on it yet but I'm pretty sure that if I either
A.) enlarge my pulley.
or
B.) Use an alternate setup in which I have 2 idler pulleys instead of the wheels for the R&P setup.

Once I do the math on this I'll get back to you but overall, I do not recommend this unless it's a temporary setup. Also, Openbuilds now sells solid wheels (without the valley in the middle) I would recommend those for this. I believe they could also help with this issue but again this is just speculation.

 

I don't think you have had zero issues because your belt is lower than mine but rather that you've had zero issues because the ratio of your pulley to your wheels is closer to 1. Therefore, there isn't any stretching going on as the belt goes around the wheels because everything is moving at the same speed. In my case, my pulley is about 11mm and my wheels are about 24mm. Therefore for every turn of the pulley the wheels only do half that and I believe this is where my problem is. I haven't had the time to do the math on this yet but I'm 90% sure this is where my problem lies based off my observations and your images. If you have the time possibly. Could you please post the diameter of your pulley? Thanks for the tips though, if you have any others I'd be interested to hear them.

 

I'm using mini v wheels so that is diff, my pulleys are 4.75 and the mini v wheels are 4.8, so yes you may be on to something but you are loosing me on your concept. If your belt goes under the wheel, up over the pulley and under the following wheel how are you getting stretch upward due to pulley size?
I'm not saying your wrong just simply I see the idea you have resulting in just that a gear rotation difference.
I feel that the v wheels and belt placement is your issue or at least a place to look.

If your belts sit up out of the extrusion, the wheel must guide the belt down into the slot causing rub, if your belt is inside or flush like mine it sits pre guided with nothing to pinch it.
Let me take a look at your pics again see if I can help you out
Maybe mill something up fast for you to try

 

Please post a pic of the way your belt is connected

 

At this time it's late for me and I must head to bed but I'll try to do a full write up for you in the morning. Thanks for your help though, I really appreciate the effort and ideas, your posts really got me thinking. =)

 

I'd like to do this with a slight modification. Make the top belt a loop. Like a bulldozer drive. This belt would mesh with a face up belt taped in the slot of the v-slot. A filler put in first to raise it to the level to mesh.

So trying to think through how to keep the belt centered on wheels of the top assembly I though back to crowned pulleys. Like farm machinery, or band saws wheels. A flat belt running on a crowned pulley will center on the pulley.

If the solid v-wheels had a slight crown instead of being flat, then as a belt looped around them it would stay centered on the crown.

Anybody else see what I mean?

 

Just an observation...

Surely, the belt will be travelling at a slightly different speed to the OD of the v-wheels (assuming the v-wheels are running in the v-groove without slippage) so separate idler wheels sound like a good solution.

Tweakie.