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x belt grinds against idler flange [Solved]

PostPosted: Wed Apr 25, 2012 8:41 pm
by movlw
Just finished the gantry and find that the x belt rides high on the idler and grinds against idler flange making some unnecessary noise. Is this normal?
The belt does not seem over tensioned. I've tried to slack it with the same result. It also makes no difference where the motor pulley is situated.
It's as if the flange part of the toothed belt clamp should be a bit higher?

IMG_20120425_223046.jpg
Belt riding high on idler pulley
IMG_20120425_223046.jpg (174.92 KiB) Viewed 17784 times


Edit: Problem seems to have been solved.

Re: x belt grinds against idler flange

PostPosted: Wed Apr 25, 2012 10:25 pm
by AVRC
I can't tell for sure from the angle of the picture, but it seems the pulley is tilted inward slightly, which would make it ride up like this.

Re: x belt grinds against idler flange

PostPosted: Wed Apr 25, 2012 11:13 pm
by bdring
I have not seen that before, it does look like the bolt is tipped. See if there is some flash or something causing the spacer to tip the bolt.

You could also hide a little paper shim under the other end of the bracket to level it.

Re: x belt grinds against idler flange

PostPosted: Thu Apr 26, 2012 6:22 pm
by daveczrn
Not only does the bolt look tipped. The nut looks like its in the opposite direction.. maybe cross threaded? It doesn't look right that's for sure

Re: x belt grinds against idler flange

PostPosted: Thu Apr 26, 2012 6:53 pm
by IPvFletch
daveczrn wrote:Not only does the bolt look tipped. The nut looks like its in the opposite direction..
Got any closeups of how it SHOULD look? Isn't the tapered nylon end supposed to be away from the flat part??

Re: x belt grinds against idler flange

PostPosted: Thu Apr 26, 2012 7:44 pm
by orcinus
No. The nylon part goes *away* from the bolt head. Always.
The orientation in the photo is correct.

Re: x belt grinds against idler flange

PostPosted: Thu Apr 26, 2012 9:54 pm
by IPvFletch
Ok cool I got mine right, that is how I always do it, little tapered nylon end all the way away from the head of the bolt..

Re: x belt grinds against idler flange

PostPosted: Thu Apr 26, 2012 10:02 pm
by AVRC
The nut does look crooked, but the bolt appears in too good condition for it to have been cross threaded.

Can you post a another picture or two, directly from the side, centered on the mounting plate?

Re: x belt grinds against idler flange

PostPosted: Fri Apr 27, 2012 6:03 pm
by dzach
AVRC wrote:The nut does look crooked, but the bolt appears in too good condition for it to have been cross threaded.

Can you post a another picture or two, directly from the side, centered on the mounting plate?

It does rub lightly against the idler holder bracket with all screws and nuts installed properly. It looks like the belt clamp step, which gives the belt a guard distance from the gantry plate, is 0.5mm too high. Here are some photos:
2012-04-27-200909.jpg
Belt rubbing the screw head

2012-04-27-201106.jpg
Clamp step too high?

2012-04-27-201411.jpg
View alligned with plate

One can see the back of the belt as it leaves the belt clamp at the left and the socket screw head rubbing against it, at the center just below the V-wheel. The other part of the belt ( the one with the teeth ) is closer to the plate but still at a safe distance. This happens only when the gantry is close to the idler bracket. At some distance from it, the belt clears the screw head and the distance increases as it goes to the motor side.

The belt in the photos is installed all the way into the clamp jaws and held securely there. A washer between the pulley and the plate will most probably solve this issue.

Re: x belt grinds against idler flange

PostPosted: Fri Apr 27, 2012 6:36 pm
by IPvFletch
Are you certain your belt is seated up against the plate? On mine it was a real PITA to get it seated properly, but I agree, all of these are REALLY CLOSE. Once I have mine into final assembly stages (still wiring) I will know for sure if it will rub and where (I'm also quite concerned about it rubbing on the endstop switches, so I've cut them back a bit, just in case)...