1 Topic by jroos1228

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Topic: Measurement system for belt tension?

Hey guys,

I find it very odd that the only real specification I've seen for the belt tension is that it shouldn't be "too tight or too loose" (Said by the solidoodle technician on the belt tensioning video)

Perhaps someone has an amount of slack measured in in/mm? That's what they do for motorcycle chains and it works great.

The only other thing I've heard is to flick the belt and listen for a cello-ish tone. I played cello and I've gotten a lot of different notes from those belts.

Could someone maybe say which note it should be producing so that I can tune it?

I just want a good measurement of how tight the belt should be

2 Reply by agentsmith (edited by agentsmith 2013-08-07 21:14:43)

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Re: Measurement system for belt tension?

Hi,
if I remember well I hung a 300grams weight on the belt center and tightned with both screws until the difference between the low and high part (probably the slack you're referring to) was about 3mm.
Anyway the key is to have the same tension with the two belts, it doesn't matter (much) if the slack is 3 or 5mm, the important thing is that they get balanced and don't skip

Also make sure they are running parallel and don't move inside the geared wheel (cannot recall its english name right now)

Nick

3 Reply by rsheldiii

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Re: Measurement system for belt tension?

http://www.thingiverse.com/thing:38952 by our own IanJohnson.

like jroos said though, just make sure theyre even and 9 times out of 10 it's all good to go

4 Reply by jroos1228 (edited by jroos1228 2013-08-07 19:05:27)

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Re: Measurement system for belt tension?

Heres a nickle calibration I tried this morning

Could anyone maybe tell me what needs to be tightened or loosened?

Picture to follow when I get home I cant figure out how to post pics from android

<edit>

Picture is now attached.

The dot on the left side of the circle is towards the back of the printer. My phone's camera just flips things around for some reason

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5 Reply by rsheldiii (edited by rsheldiii 2013-08-08 19:34:24)

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Re: Measurement system for belt tension?

I think that's the standard "y axis is effed" look. make sure the pulleys are even in tension and then start tightening them maybe a quarter turn at a time (at the same time, all four screws) and printing more of those. I found that if my belt alignment was off there was no amount of tightness that would get rid of the slop though, so make sure you do that extra correctly.

my pulley gears would bind during the alignment phase so I actually loosened one belt completely, centered the other belt and tightened its gear on the y bar, then retightened the other pulley and centered that one, then finally centering and tightening the short pulley in the back. It seemed to work a little better that way

6 Reply by agentsmith

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Re: Measurement system for belt tension?

Yes exactly what Rsheldii said, you have to work a bit on the belts and pulleys, and make sure they are not only even in tension, but also the pulleys must be in the correct position that make the belts not to slide on one of their sides.
Also check the back shaft doesn't slide off of its side bearings, it should stay inside the printer. This is dictated by the small belt and the pulley in the middle

7 Reply by jroos1228

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Re: Measurement system for belt tension?

The small belt and pulley in the middle should be directly in line with the pulley on the stepper, correct?

8 Reply by agentsmith

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Re: Measurement system for belt tension?

In my printer the small bed is in contact with the right side of the motor pulley and the left side of the middle pulley.
Probably this is the the way the bar stays in place and doesn't slide outside the printer

9 Reply by pastprimitive

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Re: Measurement system for belt tension?

if this helps http://www.soliforum.com/topic/3509/re … ensioning/

10 Reply by ThatGuy

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Re: Measurement system for belt tension?

Anyone got a cad file floating around for the toothed pulleys? I reckon I could design an auto tensioning system for the Solidoodle with a bit of mucking around. My understanding however that each belt has 2 drive sides, and one slack side. Tension needs to be checked on both drive sides of each carriage?

11 Reply by lowell.e

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Re: Measurement system for belt tension?

I get CAD files from this supplier for many parts, like these pulleys from:
sdp-si.com/eStore/Catalog