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3dtopo

Hot End v2 Unveiled?

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It's Friday... please tell me details are going to be release soon.... I'm on the edge of my seat.

On monday they said "next week".

And what kind of details are you looking for? I did a writeup when I got my beta version, but I held back my blog post until today. So you can read my first impressions from 2 months ago:

http://daid.eu/blag/2012/08/31/ult ... v2-hotend/

 

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I really wish they would have threaded the Bowden. Seems like the best solution to the Bowden moving up problem to me.
Actually, they tried that. But there are problems with it. First, it's pretty tough to do, making construction harder. Secondly, the PFA tube gets soft at pretty low temperatures, so the connection is not as strong as you would expect. Also, with the V2 design you don't have to replace the bowden tube, while with a threaded bowden tube you also need a new tube.

But with any upgrade, there are people going to say they should have done it better and differently. That's natural.

Something else they tried was making the upper brass part from stainless steel instead. Which is a very good insulator, but it proved to be a too good insulator. Causing problems with PLA sticking to it and jamming up the machine.

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I have to agree with 3DTOPO. I think that threading the bowden tube was the best way to go. Personally IF I order the new hotend I'm going to make a spare part(the white one). Also I'm not a big fan of compressing everything with the 4 screws so it would hold(over tightening flexes the bottom wooden plate in the front-right corner). As a result of this system it seems to me that the nozzle isn't flat to the build surface(I may be mistaken).

Now that I have finished ranting, I have to say that I like the new nozzle design(not the whole hotend). Seems it will be quite easy to change nozzles(eg. 0.4mm and 0.8mm).

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I'm presuming everyone has seen

https://docs.google.com/presentation/d/ ... slide=id.p

altho i didn't see a link on this proper forum, only on that old google one.

initial thoughts are:

+1 - nozzle and tube are integrated. good move UM.

+1 - a heat break at last. I'm not convinved brass is the right choice, it should be stainless steel (apparently they tried that and it didn't work, but it works fine for the reprap boys, maybe fine for ABS not PLA?)

-1 - that PEEK part still. ugh. and yet another part - teflon this time.

-1 - bowden tube not threaded. still relying on those blue & white clips. actually I've found a great use for those blue clips - put them on the quick release fitting on the extruder end and they help retraction. they actually work for that purpose.

-1 - no active cold side, so leaving the machine at temperature is still likely to cause problems

that might sound overly negative, but isn't intended to be. actually good on UM for finally getting around to doing something about the hotend, but very sad they didn't involve the community more - what could have been an awesome upgrade looks fairly mediocre instead. as several have already commented, threading the bowden solves the (only?) problem that UM seem to have addressed here. I think destroyer had the ideal wishlist in another thread..

never mind. I might order one anyway to give it a fair try but will probably end up making my own new hotend now.

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still relying on those blue & white clips.
Martijn said they will be using different clips, my beta still had the normal white+blue clip. So we'll see what ships with the actual V2 hotend.

 

-1 - no active cold side, so leaving the machine at temperature is still likely to cause problems
They tested this, because of the gap between the PEEK and the heater block, this problem is gone. As less heat is transferred up to the brass.

Like I said, they tested threading the PEEK. It had it's own share of problems. Remember that they tested this new design on 25 machines, of which at least 6 where running producing Ultimaker Robots in mass production.

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-1 - no active cold side, so leaving the machine at temperature is still likely to cause problems
They tested this, because of the gap between the PEEK and the heater block, this problem is gone. As less heat is transferred up to the brass.

But the brass is screwed in the PEEK anyway. The only difference is that now less heat is transferred( only through the brass pipe not the AL block). The main question is if that makes enough difference to solve the problem.

Secondly the problem of clogging up was primarily because the bowden tube would pop out and then the clog would form. I already had do disassemble my hot end at least 5 times. All of them was due to clogging. A few times the white clip striped the bowden tube and lost it's grip on it.

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I'm hoping that the upgrade kits allow us to use old parts from our older hot ends.
My upgrade beta kit came without heater/temperature sensor. So you'll have to re-use those. And those are the most expensive parts of the hotend. You could save the Peek and Alu block, but I think they won't offer that option to keep order assembly easier. (unscrewing the V1 brass from the Alu is a bitch anyhow)

 

I really regret buying a spare v2 hotend now. :/
A V1 you mean?

Seeing that there will be a surplus of V1 hotends soon now, maybe people who think they can work with V1 hotends (mine work fine for example) will want to have them to make dual extrusion?

You currently cannot make dual extrusion with a V1 and V2 combined, unless you make new wooden parts for the top and bottom.

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A V1 you mean?

Seeing that there will be a surplus of V1 hotends soon now, maybe people who think they can work with V1 hotends (mine work fine for example) will want to have them to make dual extrusion?

You currently cannot make dual extrusion with a V1 and V2 combined, unless you make new wooden parts for the top and bottom.

Yes, meant a V1. Mornings without coffee make brain fall down go boom. :D

I have 2 v1's, I also have access to a laser cutter so I can make my own wooden parts. The only thing I'm missing for dual extrusion is, well, a want or need for dual extrusion. Maybe I can make a little artwork out of it captioned "Don't buy spare parts for a machine that constantly changes". Its not a mistake if you learn from it. :D

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I'll share that thought fj!

regarding active cold ends - I'd argue it's a necessity going forwards. if you leave the hotend running at 230C, that heat will still transfer up the heat break eventually without active cooling.

worse. the PEEK will insulate it and ensure it goes up. if you're running slowly or not putting out much material the same thing applies as for standing still.

the teflon insert will help somewhat but is now the last line of defence to preventing hot plastic being sucked into the bowden by retraction ready to form a plug.

I'm hoping that teflon is at least 4.5mm in length...

(and in case you were wondering, 'who leaves the hotend sitting idle at temperature?' well that's what happens when a glitch on the power supply hangs the arduino - your hot end stays hot. all night or all week until you find it's stopped..)

but the main reason I'm gutted about the teflon and PEEK still being there and no active cold end, is that this still limits the maximum temperature we can work it. this means no extruding nylon for example (at 320C) or other upcoming materials.

but I suppose that's being optimistic since we still can't really print ABS properly and even PLA curls rather too much without an official hot bed.

so roll on the hot bed!

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(and in case you were wondering, 'who leaves the hotend sitting idle at temperature?' well that's what happens when a glitch on the power supply hangs the arduino - your hot end stays hot. all night or all week until you find it's stopped..)
Actually, this burns up your Peek, as temperature regulation stops and then the 40W heater pushes the temperature well over 300C, I've seen it happen and it gives a nasty smell. The hardware watchdog should protect against this, but we cannot enable it because of the stupid Arduino bootloader.

Oh, and the "plug length" in the teflon is about 9mm above the brass. That's quite a lengthy plug you can create.

I personally think that active cooling just adds a complex part that makes more noise and wears down or breaks easier. Also, the temperature transition of the PLA going into the hotend is important. Read above when I posted about stainless steel. Making the upper part too cold and PLA turns into glue when it hits metal.

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I did spot the bit about stainless steel Daid, that's why I queried whether it's a PLA specific thing, since the reprap boys have had great success but I suspect they use ABS..

9mm is good news, the burning the PEEK is very not :( I've had it heating away all night on two occasions when it crashed - no obvious damage other than a plug, and heap of molten PLA on the table.

you're right tho, temperature regulation should have stopped too.. I can only assume I got very lucky because the ambient temperature was cool and it reached a steady state just under the danger temperature. is there a reason we can't modify the arduino bootloader?

agree about the noise too, altho it's a drop in the ocean compared with all the other noise going on ;)

nik

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We can modify the Arduino bootloader, but you need an ISP (You could use another Arduino as an ISP)

Most likely the firmware in your machine was still running, but the SD or USB communication crashed.

As for the rest of the machine noise, check how much noise the extruder drive is generating by banging against the machine, just lift if off while printing for a change. Some padding there saves a lot of noise. Add some padding on the feet, and change the X/Y motor holders from the wooden things to normal spacers. All this combined and you should have a pretty silent machine.

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I think you're right there Daid. by X/Y motor holders - you mean the wooden end caps on the top of the machine? I already have silicone padded feet but retraction is what makes the most noise - I can hear that the other side of the house, and that fan on the underside of the machine is waaay noisy too. (like an old tractor some might say ;)

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