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So I wore through the stock set of push-fit connectors on my stock hot-end. By "wore through" I mean that the teeth/barbs that hold the tubing either broke or fell out. This was likely due to the multiple jams and/or adjustments in the hot end that required removing the bowden tube multiple times. No biggy. I replaced them with some from Mcmaster that seemed to be a little bit higher quality.

The E3D end came with different push-fit connectors. Big and plastic. I started printing with T-glase and the retracts seem to be much harder on the bowden tube than other filaments. Last night, the Mcmaster connecter on the ezstruder failed. Came back to a bunch of filament that was spooled on top of my effector.

I would bet that the plastic E3D connectors will also fail given enough time/hard retracts...

Anyone tried another type of connection for the bowden tube?

Perhaps a tiny hose clamp? ... haven't found exactly what I'm looking for, but something like this http://www.mcmaster.com/#standard-hose-clamps/=ojrnj0

cope413 wrote:So I wore through the stock set of push-fit connectors on my stock hot-end. By "wore through" I mean that the teeth/barbs that hold the tubing either broke or fell out. This was likely due to the multiple jams and/or adjustments in the hot end that required removing the bowden tube multiple times. No biggy. I replaced them with some from Mcmaster that seemed to be a little bit higher quality.

The E3D end came with different push-fit connectors. Big and plastic. I started printing with T-glase and the retracts seem to be much harder on the bowden tube than other filaments. Last night, the Mcmaster connecter on the ezstruder failed. Came back to a bunch of filament that was spooled on top of my effector.

I would bet that the plastic E3D connectors will also fail given enough time/hard retracts...

Anyone tried another type of connection for the bowden tube?

Perhaps a tiny hose clamp? ... haven't found exactly what I'm looking for, but something like this http://www.mcmaster.com/#standard-hose-clamps/=ojrnj0

I would like to find a source for the plastic ones like E3D uses but here in the states. If anyone knows of a source for these that would be great. There are supposed to be some
all metal PTC connectors that are much more reliable but I haven't found them yet either. Have you noticed that the failures always occur when you use the expensive filaments?

I'm pretty sure these are the same kind that E3D uses...

Black nylon with polypropylene release, nickel-plated brass teeth

http://www.mcmaster.com/#5225k503/=ojsgdt

No?

I have went through 3 of the PTC pieces. I was in the other room and heard a loud CLANK CLANK CLANK. Sprinted up the stairs to see the tube had come out of the cold end PTC, the filament had looped up, falled down, and it got stuck in the gear teeth.

I'd love some heavy duty PTC. I'll have to check out that McMaster-Carr link and order a few and try them out. The stock ones, the brass teeth wear out and fold over.

cope413 wrote:I'm pretty sure these are the same kind that E3D uses...

Black nylon with polypropylene release, nickel-plated brass teeth

http://www.mcmaster.com/#5225k503/=ojsgdt

No?

Not quite the same as E3D uses but they certainly look better than what I have been using. I'm going to buy some of them
and give them a try. Thanks for finding these.

Hey cope413, I ordered 4 of the mcmaster ones based on a comment in another thread a few weeks ago.

They're about a sturdy as the ones that come with the rostock.

Now admittedly, I hit the extruder pretty hard now, with 120mm/s retracts, and I've gone through both original, and 3 of the new ones in the past couple of weeks.

What I ended up doing is taking my last pair, and "improving" them with the M4? bolt and JBWeld trick. Then taped the jbweld for good measure.

So far it's been about a week since I've lost a connector.

If anyone sources a bowden connector that's built for abuse, let me know.

My brain boggles at the fitting breaking but the bowden tube taking the abuse.

I actually think it's more from repeated opening/closing rather than the actual force. I can't imagine that most PTC fittings are designed for repeated opening/closing.

Seating and unseating the Bowden tube is what will kill it. I like the E3D connector because it never fights. I had one of the stock PTC fittings vomit tiny metal pieces into my J-head and no matter what I do the thing hasn't been able to print since. If you need to disconnect the tube, just unscrew the fitting itself.

If you want the "ultimate" PTC, my money is on figuring out what company makes the E3D fitting (they have a BOM on their website, I think) and seeing if they carry something that will thread into our extruders. The E3D fitting is all plastic, so it won't carve its profile into the tube and it won't get work-hardened and fail. That's the way to go.

^^^^^ This is almost to the word what I was going to reply with....

Get outa my head, lol!

cope413 wrote:I actually think it's more from repeated opening/closing rather than the actual force. I can't imagine that most PTC fittings are designed for repeated opening/closing.

I would both agree and disagree. I would say that "operating" the release incorrectly would make the repeated disconnects the culprit of failure, otherwise probably not. I work with these things all the time in industrial automation, and while I have experienced multiple brands all start leaking after only a few disconnects, most are quite robust and withstand years of "maintenance." Our pneumatic test panel is easily 20 years old and entirely comprised of these fittings in a bulkhead style, and it is used on a weekly basis.

One thing that helps when disconnecting them is to push the tube firmly INTO the fitting, then press the release collar while continuing to hold the tube on its seat, THEN pull. It's a bit counter-intuitive, but you'll be surprised how much it relieves the gripping effect.

I would think that if one is not using this procedure they might be putting unnecessary stress on the fitting, possibly weakening and shortening its useful life.

Edit: I had my idea straight but my logic backwards. Fixed.

edward wrote: One thing that helps when disconnecting them is to push the tube firmly INTO the fitting, then press the release collar while continuing to hold the tube on its seat, THEN pull. It's a bit counter-intuitive, but you'll be surprised how much it relieves the gripping effect.

How about that! It works great. Wish I knew this before!

Welp, I lost my cold-end stock PTC yesterday to a failed collet. After seeing the amount of slop that had worn into it, I'm starting to think that this application goes a bit beyond the design intent for tubing movement. That or the stock fitting is of inferior quality...

Good news, though. The stock (and most commonly used in 3D printing community) fitting has an M5x0.8mm straight thread. This is almost identical to a #10-32 straight thread, at least for short thread engagements. I had easy access to more than one brand/variety of #10-32 PTC fittings, and I am currently testing.

The difference, quantified, for those interested:
- 5mm = 0.1969 inches --> #10 diameter = 0.1900 inches
- 0.8mm thread pitch = 0.0315 inches --> 32 thread pitch = 0.03125 inches

I wrapped the #10-32 thread with some teflon sealing tape to take up the gap, and there seems to be no reason why this isn't going to work long term.

http://www.amazon.com/SMC-KQ2H04-M5A-Co ... m_indust_1


I'm using these. I went through so many of the ones sold by SeeMeCNC. These don't have teeth, I believe they use an o ring to grip the tube.


My theory on why the others connectors didn't work was because rapid retracts caused the teeth to bend and weaken. These new ones I'm using haven't failed yet.

daftscience wrote:My theory on why the others connectors didn't work was because rapid retracts caused the teeth to bend and weaken. These new ones I'm using haven't failed yet.

Agreed. I'm using an all-metal fitting right now and the grip it has is night-and-day vs the stock SeeMeCNC, even when new.

edward wrote:Welp, I lost my cold-end stock PTC yesterday to a failed collet. After seeing the amount of slop that had worn into it, I'm starting to think that this application goes a bit beyond the design intent for tubing movement. That or the stock fitting is of inferior quality...

It's designed for air hoses, but all the high-pressure feeding and retracting of filament makes the collet work-harden until eventually it fails and vomits tiny pieces of itself directly into your hot end. I lost my J-head that way - never did manage to get it working after that.

The E3D hot end's Bowden fitting uses a different threading. If the EZStruder had a fitting that would accept that, it would be absolutely perfect. It's all plastic and it doesn't gouge the tube or cause other problems. If you want my opinion, all plastic is the first place to look. Plastic won't work-harden like those metal teeth.

The BSP fitting that E3D uses is actually not all plastic, if you take out the part that actually grips the tube, its got little pieces of hardened metal fused into the plastic, which grips the tube. If you pull hard enough on the tube, the metal pieces will dig into the tube, but far less than the SeeMe connectors or any others.

FWIW, with the stock SMC fittings, after inserting the tube into the fitting completely, I held the tube in place while pulling up on the blue plastic collar, then used a small zip tie around the gap in the collar and metal body to prevent it from moving. Although a recent change, I have not noticed any play in the tube when the extruder retracts anymore...

After I snapped my first connector, I ordered a set of 3 more... now they are all broken except for one and I have made another order. I would really love to find some better ones. The first time I snapped mine, I ended up using epoxy to glue the tube to the broken fitting and that worked quite nicely, assuming you don't ever need to remove it (you can still unscrew it from the end, just not quick release it). I have ordered the E3D hotend and should receive this monday. My plan is to install that, and then epoxy the fitting at the top. This should net me with no slop with the tube, but still allow me to remove the tube from the hotend side (which is mostly the one that I disconnect anyway).

when you get the E3D end, take the aluminum cylinder out of the ezstruder and drill and tap it to handle the E3D connector. They don't break.

cope413 wrote:when you get the E3D end, take the aluminum cylinder out of the ezstruder and drill and tap it to handle the E3D connector. They don't break.

I have no experience with this, I'm afraid I might just destroy it (also, I don't have the proper tools).

I think I found the source of the E3D connectors...

http://www.newageindustries.com/downloa ... Acetal.pdf

Trying to track down someone with stock...

None of the links are for the right ones guys, sorry! I am keeping my cards to my chest a little on this one. The guys we deal with don't do retail either, or buying online.

But the thing to bear in mind is that our couplers are modded by us when we get them, which allows you to pass the tubing right through.

We will get the couplers on our site for order tomorrow. I'll try and get them cheap. something like £2.50 including being modded.
We also have some SUPER cool new plastic couplings http://e3d-online.com/RepRap-Spares-Mec ... uct_id=101
You just push them into a printed hole in a part with finger pressure, and they bite into the hole. Super compact.

We also have a sale on everything at the moment, so the prices for those is only £1.20 or so. Hotends are only 35.20 too.

I also have a little printed plastic clip idea that will eliminate retraction induced rattle and wear. Just a little C-shaped spacer that goes beneath the collet.

Will keep you updated.

Sanjay

daftscience: are you still happy with these ones? http://www.amazon.com/SMC-KQ2H04-M5A-Co ... m_indust_1
I am thinking of picking some up.

Anyone find any other good ones? I bought some from robot digg and I can see the ptfe move up and down on retracts. I am printing some little spacer clips to stop it but not holding my breath....

update: the clips fit perfectly in both the robot digg and seemecnc pushfits. Attaching the STL's. I think the robotdigg one will also fit on the seemecnc push fit. It is a beefier design. It prevents the bowden from moving. Print at 0.1mm layer height.

The clips may be a bad idea though... for some reason the ptfe is moving on retracts while the clips is holding the blue piece in place. I will replace the push fit and see if the new one does the same.

I put a little dot on the PTFE with a sharpie to use as a reference to see if the ptfe is moving in the fitting during a retract. Mine was... replaced the fitting and it seems better... at least for now. Will keep an eye on it long term.

xnaron wrote:daftscience: are you still happy with these ones? http://www.amazon.com/SMC-KQ2H04-M5A-Co ... m_indust_1
I am thinking of picking some up.

Anyone find any other good ones? I bought some from robot digg and I can see the ptfe move up and down on retracts. I am printing some little spacer clips to stop it but not holding my breath....

update: the clips fit perfectly in both the robot digg and seemecnc pushfits. Attaching the STL's. I think the robotdigg one will also fit on the seemecnc push fit. It is a beefier design. It prevents the bowden from moving. Print at 0.1mm layer height.

I use these hitch pin clips from Harbor Freight, there is a size that fit the push connectors perfectly and prevent it from going down. http://www.harborfreight.com/150-piece- ... 67557.html