Belt on outside

discussion of design changes / improvements / suggestions
microwavesafe
Posts: 48
Joined: Mon Apr 09, 2012 5:47 pm

Belt on outside

Post by microwavesafe » Tue Jul 03, 2012 4:34 pm

I was getting annoyed with myself for crashing into the belts at either end of the x axis and it got me thinking about putting the belt on the outside of the x axis brackets. So I modified my previous belt clamp design and moved the clamp section over, fitted metal spacers to the stepper motor and routed the belt. It actually seems to work quite well.
Belt Clamp iss2 1.jpg
Belt Clamp iss2 1.jpg (228.87 KiB) Viewed 26404 times
Belt Clamp iss2 2.jpg
Belt Clamp iss2 2.jpg (182.55 KiB) Viewed 26404 times

microwavesafe
Posts: 48
Joined: Mon Apr 09, 2012 5:47 pm

Re: Belt on outside

Post by microwavesafe » Tue Jul 03, 2012 4:36 pm

The prototype is in acrylic, but because of the flex, this will have to be done in aluminium. It also provides some protection for the belt from swarf. I can't see any reason why this design would have a negative impact?
Belt Clamp iss2 3.jpg
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Belt Clamp iss2 4.jpg
Belt Clamp iss2 4.jpg (193.84 KiB) Viewed 26403 times
Belt Clamp iss2 5.jpg
Belt Clamp iss2 5.jpg (187.99 KiB) Viewed 26403 times

edwardrford
Posts: 1250
Joined: Mon Apr 09, 2012 5:40 pm
Location: Dixon, IL
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Re: Belt on outside

Post by edwardrford » Tue Jul 03, 2012 4:45 pm

Amazing! I'm delighted right now.
Shapeoko 1 #0 - a couple of upgrades.
Shapeoko 2 #0 - a couple of upgrades.
Shapeoko 3 #2 - Stock

zimmer62
Posts: 81
Joined: Fri Jun 22, 2012 4:51 pm
Location: Lansing, MI

Re: Belt on outside

Post by zimmer62 » Tue Jul 03, 2012 5:01 pm

I like it, it makes the usable bed size much bigger, My Y is limited even more right now when I added the second motor.

alpha
Posts: 174
Joined: Thu Apr 12, 2012 2:49 pm

Re: Belt on outside

Post by alpha » Tue Jul 03, 2012 6:13 pm

I'm also adding another Y stepper soon, I think I will use your design to add more room and save the belts from being crushed :D

What are the metal spacers you used and what type of M3 did you use for the steppers? I guess the BOM is like:
4 x M3x?
4 x metal spacers
2 custom belt anchors

Did I miss anything?

Burke LaShell
Posts: 90
Joined: Tue Apr 10, 2012 12:42 pm
Location: Philadelphia, PA

Re: Belt on outside

Post by Burke LaShell » Wed Jul 04, 2012 3:25 am

Brilliant!

Why are such obviously brilliant ideas so difficult to see? :x

microwavesafe
Posts: 48
Joined: Mon Apr 09, 2012 5:47 pm

Re: Belt on outside

Post by microwavesafe » Wed Jul 04, 2012 7:00 am

Thanks for the positive feedback!

The spacers are actually M3 threaded male to female 22mm. Although 22mm to 30mm would be fine, I just happened to have these lying around. Screw the male part of the spacer tightly into the stepper (gently tighten with socket driver or spanner), then use the standard M3x8 hex bolts through the plate into the female side of the spacer. The connection is very solid.

The idler just needs turning around and you lose one washer and the spacer, so you end up with. Bolt / washer / plate / washer / idler / washer / nut.

To mount the custom brackets you have to use longer bolts than normal, I've ended up with M5x20mm. You then use the M5x10mm that were holding the plates on for the actual belt clamp.

I've attached the dxf of the custom bracket, but please bear in mind that I've only gone through two prototype tests at the moment, so it might not be perfect yet. The top two holes are 4.5mm to be tapped out to M5, and the belt tensioning hole is 2.5mm to be tapped out to M3. Here you will need two additional M3x10mm to screw through and tension the belt after assembly. Edit: I had to change the extension to .txt to get the board to allow me to upload, please change it back to .dxf to use.

So BOM for each side

2 Custom mounts
4 M5x20
4 M3 22mm male to female threaded spacers (can be 22mm to 30mm, but I'd say 25mm is best)
2 M3x10

Next I need to try cutting these out of 5mm aluminium.
Attachments
Belt Clamp Iss2.txt
(13.79 KiB) Downloaded 1185 times

Will Winder
Posts: 435
Joined: Fri Apr 20, 2012 2:40 pm
Location: Hudson, MA
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Re: Belt on outside

Post by Will Winder » Wed Jul 04, 2012 11:55 am

The cheapest I could find 8x of those 25mm Spacers was this ebay auction:
http://www.ebay.com/itm/25-pcs-brass-st ... 500wt_1077
ShapeOko #367: Dual-Y drive, Belt on outside, 1000mm Y-Axis, DW660 Spindle, Nema-23 X/Y motors.

Primary developer on Universal Gcode Sender.

alpha
Posts: 174
Joined: Thu Apr 12, 2012 2:49 pm

Re: Belt on outside

Post by alpha » Wed Jul 04, 2012 2:12 pm

I wonder if microwavesafe's new mounts design could be merged with Edwards new plate design? Or just mount two of Edwards new x plates, I wonder if this would work too?

PLHS54
Posts: 60
Joined: Sun Apr 22, 2012 7:36 pm

Re: Belt on outside

Post by PLHS54 » Wed Jul 04, 2012 6:30 pm

Nicely done microwavesafe. I've come up with something very similar and I'm currently in the optimizing process. I'll start a new thread when I'm done

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