Another Belt Configuration

discussion of design changes / improvements / suggestions
Improbable Construct
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Another Belt Configuration

Post by Improbable Construct » Mon May 14, 2012 11:01 pm

So I have been running a dual drive setup using the alternative belt configuration that Edward had suggested in the following post on the old google groups site.
https://groups.google.com/d/topic/shape ... discussion

I have had good luck with this setup but I found a lot of dust and chips getting into the belt grooves. Also, I lost about 35mm of working space because of the X axis plate was hitting the belts.
So I did a bit of drilling and now have this setup:
ShapeOko 001 (Large).jpg
ShapeOko 001 (Large).jpg (84.57 KiB) Viewed 7314 times
Now the belt runs close to the Maker Slide with the teeth down. I drilled new holes for the smooth idlers and moved them down about 13mm. I had to trim 2mm off the bottom of the X axis motor plate so it would clear the smooth idlers but, what I should have done was move the back hole 1-2mm away from the motor and the X axis plate would clear the smooth idler. It would put the Idler tight to the V Wheel but there should be room.
I also made some mods to the way the belts are attached. I used a fender washer on one end to clamp the belt.
ShapeOko 003 (Large).jpg
ShapeOko 003 (Large).jpg (116.11 KiB) Viewed 7314 times
And I used a piece of 3/4"x3/4"x1/8" aluminum angle and the original belt clamp pieces for the other end. I tapped the holes for the bolts that clamp the belt. It lets you really pull the belt nice and tight.
ShapeOko 002 (Large).jpg
ShapeOko 002 (Large).jpg (69.2 KiB) Viewed 7314 times
I modified the X and both Y axis drives in this way and it seems to be working out great!
It also increased my working area from 170mmX205mm to 205mmX205mm.
Let me know what you think.
Shapeoko #Classified some of the bolts may be original parts.
Shapeoko 1 # ???? Stainless plates, still in the box.
Shapeoko 2 # 3926 not stock
Shapeoko 3 # 0003
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Improbable Construct
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Re: Another Belt Configuration

Post by Improbable Construct » Mon May 14, 2012 11:06 pm

Here is a picture of my belt clamp:
ShapeOko (Large).jpg
ShapeOko (Large).jpg (60.22 KiB) Viewed 7313 times
This was my first attempt, you can see where I tapped the holes, I drilled them with too big of a bit the first time because I don't have a 4.2mm bit. I ended up using a #21 bit and that seems to be okay. I made three more and they seem to be holding.
Shapeoko #Classified some of the bolts may be original parts.
Shapeoko 1 # ???? Stainless plates, still in the box.
Shapeoko 2 # 3926 not stock
Shapeoko 3 # 0003
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DrRob
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Re: Another Belt Configuration

Post by DrRob » Tue May 15, 2012 6:47 pm

Improbable Construct wrote:Now the belt runs close to the Maker Slide with the teeth down.
Clever!

I find I keep catching things on the belts, which could lead to an accident sooner or later (such as a stretched or split belt, for example), and moving them right down close to the makerslide would help a lot to avoid this.

Also, there's quite a bit of flex in the belt anchors with them poking up in the air like they are, which adds to the "give" in the whole system.

Nice idea - thanks for sharing it.

Rob.

edwardrford
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Re: Another Belt Configuration

Post by edwardrford » Tue May 15, 2012 6:59 pm

Pretty slick setup. I like that a lot.

The easy part about the idlers is they don't have to be precision aligned with anything, their only purpose is to provide tension for the belt. I might try this setup on mine, although I haven't had any problems with stuff getting on the belts. Or, more specifically, stuff gets on the belt but it hasn't effected the operation of the machine. My biggest problem was getting stuff on the makerslide and jamming the wheels up.
DrRob wrote:... Also, there's quite a bit of flex in the belt anchors with them poking up in the air like they are, which adds to the "give" in the whole system...
Rob.
I like to bend the anchors 'back' slightly. This gives the belt a little more tension and makes the anchors stiffer.
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

Improbable Construct
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Re: Another Belt Configuration

Post by Improbable Construct » Tue May 15, 2012 7:44 pm

One thing I forgot to mention.
You also have to switch your motor direction if you flip the belts.
The belt rides on the other side of the pulley and therefor reverses the direction of movement.
It was blind luck that I did not home the axis before I fired it up and jogged the X and Y.
It was quickly apparent I needed to reverse the motor direction.
Shapeoko #Classified some of the bolts may be original parts.
Shapeoko 1 # ???? Stainless plates, still in the box.
Shapeoko 2 # 3926 not stock
Shapeoko 3 # 0003
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Max Metz
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Re: Another Belt Configuration

Post by Max Metz » Wed Jun 13, 2012 6:03 pm

Hello Improbable Construct, I have been playing around with your very elegant idea of changing the position of the Idlers in my Sketchup model.
MyBat Shapeoko 002 Alt Belt setup.jpg
MyBat Shapeoko 002 Alt Belt setup.jpg (110.84 KiB) Viewed 7176 times
When changing the direction of the Motors for this modification, is that done in the grblshield controller to motor wiring or is it something different - thanks in advance. :D

Tom Smith
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Re: Another Belt Configuration

Post by Tom Smith » Wed Jun 13, 2012 6:11 pm

With this setup, is there any reason that the idlers couldn't be attached to the same bolt as the V-wheels? Does that not provide enough tension?

Tom
_______________
ShapeOko1 191

edwardrford
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Re: Another Belt Configuration

Post by edwardrford » Wed Jun 13, 2012 6:17 pm

So, interestingly, I've tried that configuration before. In fact, i tried it last November after I had already ordered most of the parts. it was one of those "AHA!" moments. Or so I thought. Ends up that it doesn't work. At least it didn't work for me. Seems that the angle is too shallow to provide reliable 'grip' on the pulley.

I'm definitely not trying to dissuade someone from trying it out. Who know, I may have overlooked something and I'm glad to see the idea might be revisited. In fact, I might try it again on my test rig.
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

Max Metz
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Re: Another Belt Configuration

Post by Max Metz » Wed Jun 13, 2012 6:20 pm

If attacking the idler wheels to the v-wheel bolts provides enough tension (I don't know the answer), that would be an absolutely brilliant solution Tom. :D

Edit: Posted before seeing Edward's post

Improbable Construct
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Re: Another Belt Configuration

Post by Improbable Construct » Wed Jun 13, 2012 8:36 pm

When I first tried this setup, I left the idlers in the stock position. It did not work at all. There was not enough tension on the motor pulley. When I lowered the idlers, it put enough tension on the motor pulley that I have only had it skip if I crash the gantry into the end plates. I don't think that mounting the idlers to the v wheel bolts will provide enough tension on the motor pulley

Max Metz I think you will want to move the idlers as close to the motor pulley as possible. The rear one really cant move, if you want to keep maximum X axis travel, but the front one can slide back a bit toward the motor pulley. It will increase the contact area between the motor pulley and the belt. More contact=more teeth engaged=less chance of skipping.

As far as how to reverse motors, I don't use grblshield controller so I don't know if you can do it in the software, but you can swap the wires around to get them to revers direction.
Shapeoko #Classified some of the bolts may be original parts.
Shapeoko 1 # ???? Stainless plates, still in the box.
Shapeoko 2 # 3926 not stock
Shapeoko 3 # 0003
Store:
http://ImprobableConstruct.com
Twitter:
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