Quadrap CoreXY update, added endstops and extruder
Some progress with quadrap core-xy, installed end stops, flint extruder and heated up chinese 0.4mm bowden j-head clone.
Homing works fine after I figured out how to configure repetier…
I think the extruder works fine but there seems to be a problem with the hotend. Although I heated it to 265°C it takes a lot of force to push the melted filament through the nozzle. I’m not sure if the temperature is too low (wrong Termistor config in repetier?) or there is a problem with the hot end design. Any ideas? I heats up well, I installed a 20W/24V cartridge heater. Unfortunately I don’t have measurement equipment to check the actual temperature, I think that would help.
I also have some problems with the z axis, when I move it down more than 100mm it starts to block and the steppers loose steps. I think I need to find a way to allow the nuts to move in x and y direction to compensate for tolerances of the ACME screw. The nut also squeals sometimes.
The heating pad also needs to be fixed and tested. I converted my ramps board to 24V and changed the FET for D8 so I can connect a 350W heater without a relay
Get some superlube for the zscrew. You will be glad you did. The 4 rods has a lot of chance for over constraint. Disconnected the screw and move by hand. It its difficult at all you have some shimming to do on your rod mounts.
@Daniel_F hotend problems are fun, sure enough. I could write a small monograph if I weren’t too lazy, seen some of them already - E3D, these J-heads from CHina, Makergear’s latest version (for some reasons RUssians love this one), and finally gave it all up and now am cooking my own.
First of all - I presume you are dealing with ABS right? Even 265 is too hot for PLA…
Second - I can but agree that the temp reading you get is never perfect. FIrst of all, remove whatever presses yout filament to the flint wheel. Heat hotend to 265, remove filament, cut end< insert filament, feel for sharp corners while the filament travels to the tip. If it catches on something - chances are this something needs to be smoothed.
Third - still in manual, increase temp. Some plastics of mine print best at 280! Others at 260, you never know. Up it from 265 to say 285 (or until things get funny - smoke, burned plastic out of the nozzle etc.) Try pushing plastic by hand - it should be extruded almost effortlessly. If it does not - disassemble everything, clean everything and check for problems. Maybe you are unlucky and the nozzle got clogged with something. Or maybe the nozzle needs a bit of polish on the inside. Plenty can happen.
Ah yes, I forgot - are you cooling your J-head? You must cool the black PEEK part, that’s important. If you don’t - install a tiny fan, 40x40 is enough, but without it things won’t be as good. And fix your thermistor well - mine fell out and the whole thing melted in less that 5 minutes, just as I walked out to get a coffee. Stinks like bad chemical crap, PEEK does…
@Shauki correction - I have actually replaced an E3D with that self-made one 
The J-head melted long ago and was converted into a PLA hotend with PTFE thermal barrier.
But this all-metal one is an experiment with stainless thermal barrier and simple methods of construction. And it works! Have to work a bit on the tip though - the copper one is too flat in the end and leaves a rough surface.
Thanks for your suggestions.
Agree with the hotend, it was congested. After cleaning it with a hot air gun it seemed to work for a while but congested again at the next atempt. Now again It is hard to push the filament through the hotend. The flint extruder works well.
I was thinking about buying an e3d but I’m not shure if it works well with ABS. Three are not many options for 3mm bowden–apart from building it myself but I think without a lathe that is quite difficult. Shauki, did you change from 3mm to 1.75 because it is easier to drill smaller holes or to allow the ptfe liner to fit into the peek part? Or because it needs less force for the extruder?
For the Z problem I think Eric pointed me to right direction. After releasing the screws of the bars that connect the two sides with the lead screws it got better. The columns on each side are parallel but the two sides are not. Giving up my nice 12mm colums is not an option…
@Daniel_F I have switched almost exclusively to abs with my e3d v6. It works great. I am using 1.75mm.
@Daniel_F E3D works great with ABS (with PLA too, for that matters). My problem with it was that I have about 4 kilos of plastic of diameter that’s sometims a tad larger than 3.2 which is the inner diameter of E3D - therefore, to get rid of all that plastic I desided to design my own with an inner dia. of 3.6. It turned out to be easy enough.
J-Head works after cleaning but gets stuck - what about cooling it? I remember it fixed a similar problem of mine, back when I was beginning.
@Shauki I do it without adapter - just tighten the drill bit in the vise (with a bit of aligning it to the chuck…) and the metal piece in the chuck. This technique turned out to be quite error-proof. The thin middle part on the temperature barrier is done the same way - metal rod rotating in the chuck, and metal is removed with file or, in my case, with a cutoff wheel.
Best method of fixing the drill bit in the vise - clamp it in the chuck upside-down, move chuck to vise, fix drill bit end in vise, unclamp chuck.
Hi again (long time I now…)
Thanks for all your suggestions, and thanks @Shauki for even offering me to send me one of your 3mm hot ends. As I’m running on 24V I would have had to change the heater, maybee even add a thermistor (and hence spoil your concept…
Therfore I decided to rely on E3Ds V6 hotend to be able to focus on the other parts of the printer.
Finally I was able to print my first test part today, I’ll post it later. There is room for improvement but slowly I’m getting closer…
Although I thought the Flint extruder woks ok, it might have a problem with 3mm filament. As it needs rather high pressure to get the 3mm abs filament through the 0.4mm nozzle, the extruder was not able to drive the filament through the nozzle fast enough with print speeds above 80mm/s.
I’m not sure wheter the hotend has too much “resistance” or I need to convert my extruder into a geared one with a 5:1 planetary gear. Like the one @Eclsnowman just built. But my plan was to get speeds up to 150 or 200 mm/s.
@Daniel_F great job. I would love to see a video of some of the mechanics in motion.
I am really liking my new extruder drive. Only issue I had was the Teflon tube popped out of the retaining nut when trying to print REALLY fast and likely too cold. But then I switched to a 4mm nut with more bite into the tube and now all is good. I love the ability to brush the gear clean mid-print if my settings are less than perfect and grinding has occurred.
which side of the cube do you mean, the sides or the top?
@what temperature do you print abs? I think the surface on the sides is bad (in the lower part) because when I started the print @230° the extruder was not able to push out enough material so I helped it a bit (“manual” mode). Of course I could not push with constant presure…
I just did it to allow to continue the print, the printer started printing into the air and I wanted to have something to check measurements.
The top surface is bad because of missing infill (I think). I might try to print the cube again@260° tonight.