First one good - can't do another. Bowden problems

[mgg942 0]

Recently completed assembly of my new Ultimaker kit. A few hiccoughs along the way - just enough to keep me on my toes.

My first print was very satisfactory (PLA using Cura 13.04 defaults) - but I've been unable to do a second one.

The second attempt started well and went along OK for, I guess, 10 minutes. After that I noticed that progress seemed very slow and eventually realised that the Bowden cable had popped out of the extrusion head, This is an Ultimaker Rev 4 extrusion head with an injection moulded V shaped piece to retain the Bowden tube clamp (Shown here: http://www.flickr.com/photos/ultimaker/8637890156/lightbox/

- though my wooden piece had no TOP marking.)

Much reading of troubleshooting, posts etc.

Stripped the hot end - found no blockages.

Re-assembled, taking great care to precisely follow the assembly instructions.

But, no luck.

Dis-assembled again - found no blockages. Re-assembled, fed filament through by hand, seemed OK.

Tried again.

Reverted to the design that I had printed successfully. Started off fine, but after a few minutes I could see from marks that I'd made on the Bowden tube that it was coming out, so aborted the print. Found that the tube pulls out easily, even with the retaining clip still in place. Tried the other end - just the same.

So I've ordered 3-for-the-price-of-2 Bowden tubes.(BTW I think that the Bowden tube clamps should be available separately)

It's more than possible that my initial assembly was lacking in some way, and, perhaps, once the Bowden tube has been forced out the situation is irrecoverable without new parts.

It does seem however, judging by the number of posts that document Bowden issues that the design is marginal at best.

I did like the design posted recently of an elongated PEEK part to which a larger diameter Bowden tube is screwed. One less part and a securer connection out in the open. Unfortunately I don't have the facilities to make something similar.

Mike.

 

[gr5 2,265]

Something is seriously wrong. I've pushed filament through manually (not using the gearing) with my full strength and the bowden tube didn't come off. I'd say maybe 80 pounds force. I had to hold the feeder down with one hand and push on the filament with the other. So I assume you can pull on the bowden (either end) with 80 pounds force and it will stay on although I'm afraid to try.

 

[gr5 2,265]

I think those things that hold the bowden tube to the ultimaker might be available very cheaply at plumbing stores. Someone mentioned this once. So you might be able to get one today and be back up and running sooner.

 

[mgg942 0]

Thanks - I've just tried the test you described. One hand pushing the filament and the other in contact with the Bowden tube at the extrusion end. As soon as I started to push the tube started to move out of the head. Not much effort at all.

And thanks for the plumbing store tip - I'll try that this morning.

Mike.

 

[mgg942 0]

Plumbing supplies didn't have it but the guy suggested a shop that sells domestic water filters. I went there, showed the fitting which they recognised. Asked how many I wanted - I said half a dozen - he said that we don't carry them, except as part of a kit. But, we do scavenge them off old filters and he gave me two!

Works at treat, even on this Bowden tube which has been through a bit. Might be to the good, I suppose, roughened up the surface.

I think the fitting is ex US as the tube measures closer to .25" O/D and .125" I/D than it does to any metric size. If only we could track them down....

Printing as I write.

Happiness reigns!

Mike.