x idler bracket clamp splitting

Just noticed that the front clamp on my x idler bracket has a split part way across it. I think I read somewhere that there's a new design for this part in the works. If this is the case, can anybody give me an indication of how long I have before this whole thing fails so that I can decide whether to wait for the new design or bite the bullet and print myself a new one now?

As the bracket is already split I think printing a replacement now would be your best solution. Being prepared for an imminent breakage would be wise.

I am waiting in the Kit queue which, I believe, is currently on-hold until nophead resolves these issues. Once I have printed the obligatory Android I think I will trun my attention to printing replacements for critical parts like the X-idler etc.

My X idler bracket (and motor bracket) split a while back. I printed and fitted new ones (before nophead kindly sent replacements).

A week later the idler bracket split again. Not all the way through though. It's been like that for a month at least and doesn't appear to be getting worse so I reckon you could afford to wait for a new design.

I think there's a new design for the X motor end as well now?

I was very tempted to print the idler / motor ends in nylon. I didn't, because I thought nylon would flex too much but I now think the brackets are thick enough to be stable and the clamps would be much tougher.

I'm considering "painting" over the split with some thick ABS slurry at something like 6:1 or 4:1 dilution (aka "ABS cement") to reinforce the surface as an interim measure. Any opinions on whether that's a good idea?

Neat acetone welds ABS parts together very well providing the gap is small. For larger splits/gaps I have used Wilko Hard Plastic glue very successfully; it's quite viscous so you can smerge it around to fill gaps well. Glues PLA too.

Here is a clamp you can add to the front bar to stop the idler bracket slipping: -



You will need m3 x 20mm screws, nylocs and washers though. The new X ends have the equivalent of a pair of these each side so use 16 extra screws.

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[www.hydraraptor.blogspot.com]

Hi Chris,
The bar clamps on the x-ends has been a weakness in many x-end designs. One of my clamps cracked also despite being so careful while tightening (my own printing). Your indication of a change to a clamp style design, where I presume the clamping tab is printed so it's layers are in compression instead of shear, will be a good improvement. I think the benefit may out weigh the additional screws needed. Have you published the new x-end designs yet?

The clamp (above) is a good interim solution.
Tks,
Ivor

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[numbersixreprap.blogspot.com]

nophead Wrote:
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> The new X ends have the equivalent of a
> pair of these each side so use 16 extra screws.
Ah, sounds good. Can we have a look or even the *.scad? Thanks.
I'm in the progress of designing better X Ends with 4 screws on each bar-clamp, but my *.scad is a mess right now :/

Well I successfully printed some, despite the adhesion problems I'm having right now. I used Slic3r though, which meant all the holes are slightly off and I needed a vice to press the nuts into place. If I'd had the scad then I could have applied the "usual" tolerances to make things snug I guess. Sorry Chris, I *will* get round to fathoming out SF but right now I want to get on with making stuff rather than struggling with a tool that is shockingly user unfriendly...

Anyway, I don't know if it's related to the inaccuracies of Slic3r, but the two halves don't mate together. I've done them up as tight as I dare given that they're still plastic, but there's still a generous millimetre or so gap. Is this right?

The design has a 1mm gap but I can close it when printed in ABS. It creates some stress lines and deforms. You probably can't do that with PLA.

I have attached the scad file but it is not stand alone. I will update github with new X ends as soon as I can, hopefully tomorrow.

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[www.hydraraptor.blogspot.com]

Thanks Chris. I've dropped it into my Mendel90 scad folder and it's picking up the right config/dependencies so I might tweak it just a little to compensate for the inaccuracies of Slic3r. One thing I noticed - was it deliberate to leave a membrane between the nut trap and the screw hole behind it? It is only a single layer thick and wasn't hard to push through with a small drill bit but I notice that it appears in the SCAD as well.
EDIT: Sorry, I just spotted the 1-layer thick "support_bridge" line in the SCAD so I guess it's deliberate!

I haven't tried torquing it down yet but the item in the photo is black ABS so it should stand up to it - at least any stress marks should be easily visible. I printed two pairs in any case so I have spares.

Edited 1 time(s). Last edit at 09/13/2013 04:08AM by QuackingPlums.

Yes you can print a hole in mid air where the hexagon turns into a smaller cylinder as the outline of the cylinder would just fall down. All the flying holes have support membranes which I drill out with a 3.3mm drill.

I am also experimenting with break away support for those but the best I have managed needs a 3.3mm punch to remove them.

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[www.hydraraptor.blogspot.com]