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  1. #1

    CTC Dual Hot End - "upgrade"

    Hi Guys

    First post here, so Hi... and it seems I have found a cracking 3D forum - having not been too impressed elsewhere!

    I have a CTC dual, sailfish and around 3 weeks of use.

    Only been printing PLA, and using the right hand extruder.

    I have been having hassle with the feed skipping... ie the typical clicking from the stepper.

    I raised the hot end temp and still no better.

    So - tried manual load from teh front panel - and even then, with sailfish "in control" with temp set at 230, the motor is clicking away...every half inch of feed, then it runs for a few inches and off it goes again.

    That did make me think its temp related... ie heater on =ok, then it cools... and clicks... heater on.... etc etc

    I have stripped the hot end down, and the ptfe tube in the stainless guide had what looked like grease (brown in colour) between the ptfc and the stainless guide tube..is this normal? None in the actual filament tube "inside"... I did wonder if it helps transfer heat?

    Looking around for an upgrade (as its in bits and many posts say upgrade them)... what do I change to?

    Should I stay with the brass extruder with "fitted" ptfe tube or go to stainess extruder and cut and fit ptfe?

    In terms of the stainless guide - it has onlt 8mm or so of thread and the rest is plain turned. Is this component ok, or should I go with something better?

    Lastly - the very small (2mm?) allen key to adjust the guide height - was thinking about drilling it out, tappping it, and fitting a 3 or perhaps a 5mm grub screw in there - is that sensible?

    Thanks in advance for youe help and advice.


    David

  2. #2
    Engineer-in-Training
    Join Date
    Jan 2016
    Posts
    249
    Check to see if you can use Micro Swiss All-Metal hot end kit.

  3. #3
    Quote Originally Posted by jeffmorris View Post
    Check to see if you can use Micro Swiss All-Metal hot end kit.
    Hi-and thanks for the reply.

    I had a read up and like the idea - these dont have ptfe tube in them, right?

    Quite expensive... guess I need to check what "MK" I have - never been clear as to what all the various versions are! Think there was a wiki somewhere that tried to explain the differences.

    What is the difference between a brass and stainess nozzle? - heat characterists are different between the metals but how does that change the extrusion?

    David

  4. #4
    Engineer-in-Training
    Join Date
    Jan 2016
    Posts
    249
    I think that the difference between brass and stainless steel nozzles is that stainless steel nozzles last longer than brass nozzles. Check the manual that came with the printer to find out what "MK" hot end you have. My PowerSpec 3D Pro 2 (Flashforge Creater clone) printer uses MK10 hot ends. Micro Swiss all-metal hot ends don't have ptfe tubes.

  5. #5
    Technologist
    Join Date
    Apr 2016
    Posts
    118
    I found these: http://www.ebay.co.uk/itm/3D-Printer...lfvZl0hAxmaP-w

    Will solve your problems. They provide a much better grip onto the filament than the standard ones do. Just check these will fit your extruders, but I think they will.

    You will find that ABS does not jam as much, as it is less soft. Increasing the hot end temp feels like the right thing to do, but it may just make the filament softer further up, so will actually add to the problem.

    Make sure you clean all the gunk off the hobbed gear, as if this builds up slippage will occur.

  6. #6
    Hi Noiseboy... I did buy a pair of these a few weeks ago but they would not fit my CTC.... the thickness of the moulding was larger (thicker) than the mounting bar on the printer so that the heatsinks and fans were then sitting at an angle... which was no good and I really did not want to put washers in there to space it out.

    I checked other ebay listings and they dont seen to specific how deep they are...

    If I could find the metal equivalent of that in 14mm deep (from memory) I would but them..... but finding a seller that is going to have that info and ship me something the same as promised would be rare I suspect... especially some of the typical ebay sellers...

    David

  7. #7
    Technologist
    Join Date
    Apr 2016
    Posts
    118
    Hmm, how much thicker?
    Mine are about 1mm - or 1 washer thicker. The only important bit is to ensure that the feeder hole lines up with the hot end tube.

    Might be worth a little tweak and a play to make them fit, as I think they will solve your issue.

    Failing that, I would imagine that the all metal ones will be a better fit, as they are milled out of standard thickness material - as is the heat block. The chances are they will fit properly. Find ones with good reviews.

    On another note, check that the thermocouples you bought are insulated. Many are not, with the junction just crimped into the eye. I took mine apart and insulated them with some high temp sleeving. If not, you will find that the heater temps will be all over the place, as the thermocouples will be connected to both the heater blocks!

  8. #8
    Hi

    Thanks for the ideas and advice.

    I have ordered some metal feeders so will see if they fit and if not, use some spacers to keep it square and feeder holes aligned.

    I was wondering if there is benefit to ditching the standard ctc setup and move to new hot ends with the threaded feeder that threads through the (need to be new) mounting bar and up into the feeder drive?

    I like that idea as the feeder tube is threaded right up to the drive wheel so the drive should be more direct. So I would be effectivley be building this:

    Geeetech_mk82.jpg



    I just need to get my head around that parts list as I may try that if the metal feeders dont resolve the issue. I have not measured the thread sizes - some seem to be 6mm and some 7mm... and then the lengths - I guess the shorter the feed to extruder nozzle is better... or perhaps not, for heat reasons?

    I have also ordered a (cheapo) temperature probe for a couple of quid to use on my meter to try and get better temp readings.

    probe.jpg

    My thermistors are in what looks like a crimped eyelet - and do have some (what looks like) fibreglass matting over them to insulate them so should be ok I hope!



    Thanks

    David

  9. #9
    Technologist
    Join Date
    Apr 2016
    Posts
    118
    I've done more than 500 hours on the standard setup, including ABS PLA and Ninjaflex, so I don't think you need to replace the whole thing.

    Regarding the thermocouples, if they look like this image, they need insulating. Personally, I would leave on the originals, as they won't be very different to the new ones. Thermocouples don't vary anywhere near as much as thermisters.


  10. #10
    Hi Guys

    Thought i would update the thread now I am (for now...ish) fixed.

    I bought parts to be able to move to threaded throats or retain the originals, and did that - with the common silver aluminium extruders - that has really helped.

    I printed off a rear bracket and as the new extruders were threaded I have ptfe tube in place end to end, which saves continually watching the printer for snagging.

    The new extruders seem to have no problems haulling tthe filament through the tube which is great.

    I wanted a modified top plate to protect the cables - most dont work with the threaded ptfe tubes going directly into the extruders - and prevent the tensoon lever working. They all seem to be threaded into the top plate which would be less than ideal in terms of alignment, or at least they would be on my printer.

    Lastly - a comment re these aluminium extruders - I had to insert a washer between the stepper and bar to ensure that the exit extruder feed is perfectly aligned with the throat - as supplied they are a mile off.

    All in, a huge step forward in quality.

    Thanks for the advice!


    David

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