Replacement Hot End Different - Couple of Questions

K8200 3D Printer K8200 - Assembly and user manual
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Hi there,

Thanks for incredibly quick delivery. Every interaction with Velleman has been great so far.

My new hot end assembly was necessary as I reassembled after cleaning out a bit of stuck filament (done many times) and stupidly over tightened one of the bolts, then after a very long print (20 hours) the wax insulator was warped. Entirely my own fault the instructions clearly say to be careful with the torque on those bolts.

Anyway, the new assembly is very slightly different so I have a couple of questions:

  1. The element isn’t glued into it’s brass housing - should I get some suitable heat resistant adhesive, if so, any advice? Am not in hurry as current element just fine so whenever you (Velleman) can help that would be great, or if anyone else has any advice? I have some two part epoxy based heat sink, I usually use for vertically mounted Alu heat sinks for small ICs, perhaps this would be okay?

  2. There is a small grub screw and hole for it - perhaps this pertains to question 1 above, but the tapped hole for it doesn’t actually extend through to the hole for the element, else I’d have assumed that it was for securing the element in place. I could just drill it though and re-tap a new thread and put in a little bolt, although I don’t have any taps that small and brass might be tricky to just drive a bolt into - perhaps I’m remembering, but I think I can remember from material science at uni. that brass is harder than steel, but could be wrong! Perhaps that wouldn’t matter and I could just get a little bolt in there with a bit of persuasion and a sacrificial bolt or two!

  3. There is the white wax insulator that pushes through the machine Alu bracket which in turn supports the whole assembly. That smaller insulator wont fit all the way though into the bracket to go flush. It cant be more than 0.2mm too thick and its just wax vs aluminium, so I could very easily push it though, but jsut want to be sure that its not supposed to just go in a bit perhaps

  4. The nozzle diameter looks smaller than the old one. Is it less than 0.5mm? That’s fine if it is, in fact that’s great as I still have the old one it will be fun trying thinner extrudes. But perhaps I’m just imagining it!! Perhaps the old one is less than 0.5 and has just opened up a bit, although I cant imagine how with just liquid plastic going through it.

  5. The rest looks identical, well except perhaps the extra few holes in the bracket, but I’m sure those must be to save weight / material or perhaps it is a revised part that also fits a revised feeding mechanism or something?

Thanks!!!
Danny

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Right, so ignore 1 and 2 I am clearly an idiot - there is a second hole for the grup screw on the other side - I must be blind. I blame the traffic on the motorways this evening. 15mins from central london to the M4 and then an hour to get to reading - and this is on a motorbike, I nearly went mad. Anyway, questions 3 and 4 are still confusing me if anyone can help! :slight_smile:

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Right, question 4 also answered using micrometer - it’s 0.43mm, so pretty much 0.5 especially considering the plastic is squirted out under pressure I expect the extrusion is very close to 0.5!

  1. So that just leaves me with whether or not to force the shorter white PTFE (I presume?) waxy plastic bit through the machined alu bracket so that it sits against the plastic part’s collar (wider, more protuberant section), or if I should leave it pushed to where it wants to sit (face of plastic is flush with the bracket, ie not protruding at all and the collar is hence left 3.3mm short of the bracket). It seems to look fine like that - just odd that the collar is so far away when it looks like its purpose must be to sit against the alu bracket and stabalise the hole assembly - resist any torques applied by say the head fouling on a printed part that has warped with the heat, and I’m not entirely sure why it has stopped there unless there is a slightly conical slant to the platic part & the alu part, which would seem rather tricky to manufacture!
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Hi dannyoneill,

the aluminum bracket may have rough edges from machining. If this should be the case, deburr it a bit, then gently push the PTFE part in. Maybe use a vice to reduce the possibility of canting. In the end, it should be a tight fit between both parts, so a bit of pressure is ok as long as there are no chips cut off the PTFE.

The collar should sit against the bracket like shown in this image.

Cheers,
kuraasu

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Brilliant - thanks Kuraasu!