Ultimaker Bowden Pop-Stop
by electronicsfordogs, published
This thing has moved to Youmagine: https://www.youmagine.com/designs/ultimaker-bowden-pop-stop
This little gadget is for the Ultimaker v1 Hot End and does these things for you:
- Is a printable solution to bowden slipping/popping problems
- Solves the filament plugging in the hot end problem
- Reduces the stress on any clamping solution (so the standard white clip is sufficient, if desired)
- Makes the whole linkage of bowden, filament, brass and PEEK more tolerant to minor problems and easier to adjust and service
The Pop-Stop forms a solid barrier that fits inside the wooden head block. A short length of tube provides a filament path from the Pop-Stop to the brass nozzle (inside the PEEK part). The Pop-Stop prevents the tube from separating from the brass, and through the four long screws, it allows some pressure adjustment so that you can be assured a good fit between tube and brass without ever getting leakage that causes the traditional tube plugging/slipping/popping problems.
The main length of Bowden (from the extruder) is then attached to the head and the Pop-Stop either by use of the standard white clamp and blue clip, or by an "Owen Clamp" (which is printable). It's possible to use e-clips or any other type of clamping solution - the good news is that most of the back-pressure force is absorbed by the Pop-Stop, so the clamp doesn't have to do very much work. Even if the clamp isn't very good and lets the tube slip a little during a long print, you won't get a plug and your print won't fail.
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I printed this part in 0.2mm layers (ie. "standard" quality). High quality may work better if you can do it. It doesn't take long to print, so you won't have to wait long for it. I tend to use the "Joris" feature in Cura, but it's probably be fine without it (and probably fine in other slicing software).
You need to clamp the bowden to the head. I personally use an "Owen Clamp" (found here: http://www.thingiverse.com/thing:11864 ), but you can use the standard white clamp and blue horseshoe clip (see notes below though), or any other clamping solution you happen to have.
Once it'a all printed:
- Heat up the hot end and remove the filament
- Let it all cool down
- Dismantle the hot end by removing the four long screws
- Remove the bottom wooden plate (the one above where the aluminium plate goes
- Remove the white clamp completely from the wooden plate
- Insert the Pop-Stop into the wooden block (above where the nozzle usually is) - it only goes in one way around!
- Replace the wooden plate onto the bottom of the block - it should push all the way back onto the wooden block
- Cut 22mm off the end of your Bowden tube (try to cut the end off to be as perpendicular as possible). If you cut 23mm, that's probably okay, but don't cut less than 22!!
- Push the short piece of tube into the hole in the wooden plate and make sure it does all the way up
- Re-assemble the hot end (put the aluminium plate back on). The short tube should locate into the PEEK as normal, and then push up against the brass inside. When fully assembled, the aluminium plate will not quite push up against the wooden plate (there should be a 0.5mm gap) - this allows you to tighten the tube against the brass by tightening the long screws. I found finger tight + a quarter turn seemed to work best (don't over-tighten as you'll deform the tube)
- If using the Owen clamp, thread the gnurled cap and tightening cone onto the long length bowden
- If using the white clamp, insert it into the top of the wooden head (see notes below)
- Push the bowden tube into the hole in the top of the wooden block and tighten the clamp. You need a close fit between tube and Pop-Stop, but do not need the super-strong, high pressure fit that you used to need against the brass!
- Re-thread your filament (see notes below)
- Get printing!
I'm using the Owen Clamp, because I already have one and I found the white clamp didn't quite fit in the top of my wooden block. It fits in the hole, but is too close to the walls of the block to function correctly. If your block is the same, then you can solve the problem by cutting a small amount off the wooden walls of the block. Caveat maker ;-)
It's also possible to use any other clamping solution you happen to have. "Eclips" seem to be fairly common, and will work (same caveats as the white clip above though).
I found the first time to be quite a challenge! I've found that not tightening the clamp makes it easier to push the filament through (tighten the clamp once it's threaded though!). You may also find that trimming the tip of the filament into a point helps quite a bit. Once you've done it once (and tightened your clamp) then it's easy after that.
So what's all this done?
- You now have an absolutely rock-solid connection between tube and brass. No plugs!
- The clamp you've used only needs to overcome the force of the extruder (and doesn't have to overcome the force required to keep the tube agaist the brass). This means you don't need a very strong clamp (or don't need to tighten it much)
- If the tube slips by a millimeter or two, it may affect extruding quality, but you won't "pop" the tube, you won't get a plug and your print won't fail!!
Things left to do in the Pop-Stop
- Make filament threading a little easier
- Try to improve the printing quality of the bowden tube hole in the bottom of the part - it needs a bit of cleaning up with a craft knife at the moment due to the design of the part and the tiny amounts of space available inside the wooden block
- Make an "upper" section for the Pop-Stop so that the tube meets the Pop-Stop on the top of the wooden block (which means the part lengthens the Bowden by about 50mm, and works very well with Owen Clamps and Swagelock tubes.