OverlapStrap CrudeStruder

Sometimes you think you have come up with a simple design, but when you come to real-ise that design it turns out to be much harder than you imagined to make.

So I went back to the drawing board, and came up with something even simpler. This is what I have come up with, the crudestruder.

There is nothing really innovative about this design, its just a piece of MDF with mounting holes for a NEMA 17 and some 15mm copper pipe clips to hold on the thermal barrier. I used another short piece of 16mm PTFE rod with a 4.0mm hole to act as a filament guide. The pinch-wheel is just one of the standard mendel m4 bearings, and is held using a flange of aluminium that I cut off of my original stock of aluminium angle. This pinch wheel mount is held using the same m3 bolts that hold the NEMA in place. The top hole of the mount was cut into a slot to allow minor adjustment. I use a conrad electronics splined model car insert to provide grip on the drive shaft.

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15 thoughts on “OverlapStrap CrudeStruder”

  1. That certainly looks nice and simple, if it works. I presume that big square thingy right at the bottom is going to do the heating – what is it exactly?

  2. Looks a lot like how I am making my extruder 🙂

    I have though a spring loaded screw to force filament at a constant rate against the gear.

    Speaking of which, where did you get your gear from?

  3. Like this, similar to bodgeit’s concept using mounting blocks, we need simple strap designs that people can build with simple tools.

    Not laser cut this and over machined that, need to find a way to either make or buy that heater block.

  4. The design of the frame was indeed inspired by bodgeit’s repstrap (I did give him credit for this at the start of my blog)

    The heater block was made from 3/4″ Aluminium bar, a hand drill, a hacksaw, an M6 tap, and some elbow grease. Its probably the easiest heater to make, which is why I chose that design.

  5. And like I said to him….wish there was a source of the mounting blocks in the usa. I wore my keyboard off searching for a source. No luck. Take a lot of time to make my own! You have a source for me?

  6. Thanks for the offer. I have even thought about sawing a breadboard into pieces then drilling the holes. No. There’s got to be another way. Thanks anyway.

  7. You are going to have problems with those pipe clips holding the PTFE to the board. The extrusion process generates a “metric crap ton” of force and pops those bad-boys out all the time. I would suggest a plate with a hole in in big enough to slip the heater barel through and then butt that up against the PTFE. Run some bolts through the plate up to an L-bracket bolted to your board so that the plate and the L-bracket take the load and not the PTFE.

    The other thing, the PTFE needs to be sandwiched so consider a bolt on the heater barrel too so that the plate holds the bolt which holds the heater barrel and pushes the PTFE back up into the L-bracket through which the filament runs.

    One last thing and then I’ll get to the compliments, move the pinch point down as close as you can to the entrance to the PTFE. Don’t want it kinking under load.

    The whole design of the machine looks very tight and efficient. If you hadn’t gone with a pinch wheel stepper design for your extruder I would tell you your axis might be too slow if they were threaded rod driven. On the whole I say it looks down right DIY sexy. Good work!

    Demented

  8. Thanks for the tips, I will consider doing the modifications you mentioned, and then I can actually get round to testing this baby 🙂

    With respect to the axis being too slow, I am worried about this too, and as I posted before I intend to bootstrap some basic parts using the leadscrews and then upgrade overlapstrap to a belt drive version using these parts.

    P.S Apparently a ‘Metric Crap Ton’ is an SI unit, and consists of 10,000,000 Nm 😉

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