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Sigismond0

Printrbot Metal Open Cable Chain Kit

by Sigismond0 Oct 8, 2015
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Hi Everyone

Update so-far,

Fan: The problem was traced to faulty cable ( it seems to have form a break). I've repaired the fan cable and the fan is now online & working.

Z-axis: I think I may have solved the problem by re flashing the EEPROM. Running more tests. I'll run more tests, print simple cubes etc before returning to the cable chain project.

Hi

I seems to be having problems printing the Arch part of the E-Motor mount

Any suggestion.
https://www.thingiverse.com/make:365095

Printrbot Metal Open Cable Chain Kit
by Zincury

It looks like there's a whole lot going wrong there. It looks like you're probably printing too hot, your cooling fan may not be working correctly, and there may be a fair bit of slop in your belts. Do you have issues printing other models with the same filament and settings?

Hi

Thanks for your reply. I'll try cura again but experiment with support settings.

Hi

What is the best setting for printrbot simple metal regarding support to print out the cable chain. Trying to print the Y-motor mount. Tried using the slic3r with support, 20% infilland at 0.2mm. Had problems removing supports thus producing port print. Tried cura, poor print. Will try craftware. I've notice other was able to get perfect prints. Any suggestions.

I used Cura, with the same settings you note here and it worked just fine.

I'm having a lot of issues with the rear motor bracket. It looks like prontrbot changed their motors to shorter ones with corners that aren't as cut off. Anyone else experience the same?

I'm sorry to hear that. You're more than welcome to remix and re-upload the rear motor bracket as one that fits your machine better.

Alright, I fixed it: https://www.thingiverse.com/thing:2399182

Thanks for the great design!

Printrbot Simple Metal Open Cable Chain Back Bracket - New Small Motor

Good job, thanks. My feedback:

  • On the read chain motor mount, I had to file off sharp corners on the tabs for chain attachment. I understand that they are supposed to prevent chain from bending upwards, but they did not. Instead, every time printer goes from top Z to zero Z, chain detaches there.
  • I have printed everything with 0.4 nozzle, 2 shells, 20% infill. The front chassis mount broke twice until I reprinted it full solid.
    After those alterations, all seems fine.

Sorry you had so much trouble. I don't have the Printrbot anymore, so I won't be able to look at it to see what might have caused those issues for you, but neither of those things happened to me.

For the rear chain mount, the chain should go straight backwards when the Z is all the way down, as you can see in the main album picture. Mine still had a little slack even when all the way down, full Z motion worked without issue.

For the front bracket, was it breaking where the screws attach, or in the vertical section where the links attached? If it's the former, I probably printed with enough top/bottom layers to make the flat part solid.

Now my rear chain goes 45 degree upwards, but hey, it works. The front attachment bracket was breaking in a place where the rounded wall turns into a flat one. 2cm high. I made it solid and it works.
BTW I am using extended Z height, even more extended than the commercially available upgrade. That upgrade provides rails that can go a few cm further than the auger allows. So I installed 3rd-party auger and nut to win back those few cm.

Hi Sigismond0

Is it possible to recieve some technical drawings or a file that i can import and mod in Fusion360
I have my printer chained with your files and I am now starting to build a CNC/penplotter (1meter) so I printed a lot of you chains again.
But I want to design additional Attachment points.

I'm afraid I don't have any drawings or files aside form what you see here. For the attachment points, you'll just need to take one of the chain link files, cut it in half, and add that to a 3d model that matches the measurements of your machine.

my ext. chain keeps binding on the z axis motor

Another commenter said they are having this problem with the extended Z-axis. Are you by chance using that?

sadly this chain doesn't work if you have an upgraded z-axis. at high z heights, the chain has a tendency to bow backwards and get trapped under the motor, then the chain gets snapped off.

I'm guessing that the cables are probably too short when it's fully extended on the upgrades Z-axis, meaning that chain can't retain that slight outward arc. It shouldn't go under the motor unless it got stretched so tight that it completely lost its shape. Any chance adding a few more links would solve it?

i had to add a bunch of additional links just to get it to reach. the problem (you can actually see the beginnings of it in your screenshot above) is that the cable leans back a few degrees. if your z is short (e.g. stock printrbot) it's unlikely to happen. but with a very tall z (10" z-upgrade) it is much more likely to happen.

what happens is the printer homes x and y, then z. the cable lean causes it to get caught under the motor. then it folds under, comes all the way down. and gets smashed against the front attachment point, destroying it.

i don't see an easy way to fix this.

Oh I see, I assumed you meant the rear cable. You could try changing your start gcode to home differently. I'm thinking home X/Y, extend Y by 50-100, then home Z.

Another option would be to create some links that turn 90 degrees. The top and bottom sections of the chain would be just like they are now, but with the middle of the chain collapsing to the side rather than lining up vertically. Might be too complex to be reliable though.

Edit: Also, maybe a modification of the lower mount for the front cable that angles it forward, such that the cable is perfectly vertical (or slightly forward). Could even test that by just shimming it.

There is no use to change the homing procedure because after that there is a G29 procedure that drives nozzle almost to that very corner. With new G2 board one would have to recompile firmware to change the homing procedure. However, there is a simple way to fix a problem of front chain bending backwards. Take a pencil and use a couple of zip ties to fix it vertically to the backs of the lowest two chain links. Those stay immobile any way and pencil would prevent chain from beinding backwards.

I've printed a few sections of this and found that the articulation seems quite sticky. I'm printing in PLA, and the surfaces where the links connect seems pretty smooth. Should the movement be really sinuous, or should the chain stay where it's put? Thanks!

It should be right on the edge of being free floating and slightly grabby. A few links snapped together and held out straight will not flop, but the full chain will have enough weight to bend the joints freely.

Realized I was printing at too high an infill %. Dropped it down to 25, and now the chain moves perfectly! Thanks for your help.

Sounds good. I'll print the rest of the extruder chain and see how the articulation is then. :-)

Comments deleted.

Files are not manifold. I would recommend dropping them into https://modelrepair.azurewebsites.net/ and reuploading

The scale seems to be way off on the E motor mount... even in the preview image, it's super tiny :(

Oh wow, you're right on that one. I'll look into it.

Thanks for posting.
Can you double check the y motor cable mount? The chain seems to be too wide and does not click in.

Thanks for noticing that. I've made the mount wider, and it should be correct now.

It still doesn't seem to be right. There's no indent for the chain to latch on to, and the hole that goes straight through is about 1mm smaller than the tabs on the cable.

The width part was from me being lazy when I made the file the first time around--I did my print by having the slicer make it wider. But the holes should work. Everybody else seems to be printing them fine, but I'll take a look for you.