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Good morning everyone.  I'd like your thoughts on the following:

 

I've had to clear jams on occasion, and each time I wonder what I am doing to other parts of the printer during a hot pull.  The thread from kman on the PVA mid print pull (excellent workaround BTW) prompted the same concern.

 

Then it hit me:  With removable print cores, why are we forcing all this stress on a high precision printer head supported by bendable rods?  Why not have a robust stand that you can slide the print core into, properly supported so it can withstand a cold pull without damage, power it properly to a selectable temperature  (or temp schedule) and then do the work there?

 

Now, I realise this is going to have to be a smart stand.  My initial thoughts would be arduino running some portion of the full Ultimaker firmware, but really just enough to control temperature.  There would have to be a proper electronic interface to the print core, so the power supply would have to be managed.

 

I looked around my shop and realised the hardware needs are not really that big a stretch.

 

But first impressions in this business are sometimes just a rabbit hole.

 

What do you think?  Is this doable?  Anyone up for a bit of collaboration to get it done?

 

John

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The upside of having a separate stand is, that you could take out the print core and clean it while your Ultimaker continuous to print. If you have to clean it in the 3D printer it prevents you from using it basically. Which could cost you precious time. 

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I certainly see that benefit too.  The nice thing about having a cleaning stand, especially since the UM3 (in my case) ships with two AA cores, is that even routine post print cleaning can be done on the stand.  For multi printer operations where there are a lot of cores in play, this would have to make sense.

 

Now, I know that Ultimaker and 3rd party makers like 3dSolex and gr5 know the electronics of the print core.  I don't.  That to me is the biggest unknown, managing that interface safely.  How big a challenge is this piece?

 

J

 

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1 hour ago, SandervG said:

The upside of having a separate stand is, that you could take out the print core and clean it while your Ultimaker continuous to print. If you have to clean it in the 3D printer it prevents you from using it basically. Which could cost you precious time. 

Ok...I think I have a disconnect in me head.....I had a different image....I think I shall watch this to see what you guys speak of.

 

Thanks for info :)

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I think this is a good idea, with some recent issues with my 3rd party printcore, I couldnt print on the UM3 while I try to free up the jam core.

 

A separate stand would be a good idea, more so to those multiple printer and mostly run continuously. I think it is very doable, some one already may have the code for this, there was a guy who made a sous vide annealing for PLA, the principle is the same just heat up the printcore heater and probe current temp. no need for a full code, PID would be nice to avoid overshoot. Unless you want to to automate the cold pull as well.

 

On the business side, I am no expert but as a individual consumer, I might not buy this due to price. I might just DIY it as well (open source ftw) but businesses might buy it.

Edited by jffry7

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I'm thinking open source anyway, so cost will be in the hands of the user.  Creating the physical holder doesn't look too difficult, but some thought will have to be given to heat tolerance when the print core is being heated to clear a high temp filament.

 

The electronics interface and heater power is really where it gets tricky for me.  I agree, no need for all of the features of the standard firmware,  I thought it might be easier to clone a controller, then use off the shelf firmware, but the function is basic enough that perhaps that is overkill.

 

I'm a relative novice with GitHub.  Is there source documentation for the printcore electrical interface and associated temperature control code?

 

john

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If you are talking about a standalone cleaning stand, and you want to clean during the middle of a print, then keep in mind that removing a print core in the middle of the print can give a heat error and make the print fail anyway.

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That's a good consideration. 

 

I hadn't really fleshed out my thinking enough to consider the case of of removing a print core mid print,  more I was picturing hauling on this thing while doing a cold pull and the stress that puts on the rods and blocks. 

 

Right now my RAM (which at my age stands for 'randomising aging memory') is full, trying to figure out the interface and whether there should be cooling for the upper print core.  I'm also considering whether, since we have control of the environment, it would be worthwhile to allow the stand to tilt so that the nozzle could be horizontal or pointed upwards for cleaning, for those cases where something needs to be inserted through the nozzle opening.    If that capability existed, it would be an easy stretch to add a magnifier so the user could guide a needle more precisely with less risk of damage.  Then the thought of a heated needle....

 

Welcome to the perpetual motion machine of modification.....

 

J

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3 hours ago, JohnInOttawa said:

Is there source documentation for the printcore electrical interface and associated temperature control code?


The schematics of the Ultimaker3 PCBs can be found here:

https://github.com/Ultimaker/Ultimaker3/tree/master/PCB files

 

There are some hints about how to make the electrical connections to the printcore in this thread:

Using the Ultimaker3 CORE on an Ultimaker2

 

On the Arduino side one can probably copy the heater (output)- and PT100 (input)- circuits from the Ultimaker main-board, again: the schematics are published:

https://github.com/Ultimaker/Ultimaker2/tree/master/1091_Main_board_v2.1.1_(x1)

 

And for the software, take a look at the "manage_heater" function of Marlin:

https://github.com/Ultimaker/UM2.1-Firmware/blob/UM2.1_JarJar/Marlin/temperature.cpp#L406

 

Put it all together and you have a starting point.

Good luck! 😏

 

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Yes, I can see the use of a separate print stand for printers with swappable nozzles.

 

But it would require temperature control: heat on/off, plus adjusting the temperature. And it would need a powerfull blower or cooler, to cool down the nozzle fast again. So you don't have to wait for ages.

 

Thus this would almost require the electronics of a printer: CPU-board, nozzle holder, rotating knob, display.

 

On my UM2 (non-plus) I use a much more gentle style of atomic pulls (thus the cold pull, or better luke-warm pull), to avoid damaging the rods or head.

 

I use it always when changing colors and materials. For long runs with one color, I use it occasionally to remove accumulation of burnt residu.

 

In short it goes like this:

- Via the Maintenace-menu, heat up the nozzle to melting temp (210°C for PLA).

- Then manually push through some filament until you have a nice steady flow (unless totally blocked of course). Push gently!!!

- Dial the temp to zero.

- Stop pushing filament through when the temp reaches 200°C. Do not keep pushing. This avoids getting a big blob in the teflon coupler that might get stuck when doing the pull.

- For a worn-out teflon coupler, even do a slight "manual retraction" of a few mm, when the nozzle is still around 200°C. This makes removing easier later on.

- Then let the filament alone.

- Cool down the nozzle with compressed air, if you have an oil-free compressor. Or blow onto the nozzle. This greatly reduces cooling time. If you don't have a compressor, and don't want to blow, just wait. Never use spray cans with compressed air: these contain flammable or explosive gasses, and you don't want that on a hot nozzle.

- After the nozzle is cold (=room temp, 25°C), wait for another few minutes. This gives the filament time to solidify totally internally, and in the teflon coupler too. Otherwise it might still be liquid in these insulated areas.

- Once cold, gently try to rotate the filament. But gently!!!

- Then heat up the filament again to 70°C (for PLA, other materials require different temps, e.g. PET may require 110°C).

- While heating, gently, very gently pull and rotate the filament.

- As soon as it reaches about 60°C, you will feel that the filament comes loose.

- Gently keep pulling and rotating: now the filament will come out and take the dirt with it.

 

Then restart the cycle. Do this a few times untill the dirt is removed.

 

The key is to pull and rotate very gently, with only two fingers. No brutal pulling. In this way, you never exert high forces on the rods, nor on the nozzle and spring. No risk of bending the rods or displacing the nozzle. But due to the rotating and pulling action, it still removes the dirt very well.

 

The deeper cooling to room temp allows the inner core of the filament to totally solidify. When reheating, this adds strength to the filament. Only the outer edge is then softened.

 

If the nozzle is totally blocked, you could push from below through it with a soft steel needle. I use a medical needle from which I cut off the sharp cutting edge, and then rounded the end. I also grinded it down from 0.41mm to 0.39mm diameter. Here too: push very gently, and only use a rounded needle, no sharp one, which would damage the nozzle.

 

Another thing that works: once the filament is removed, I sometimes gently clean the inside of the nozzle and teflon coupler with a brass M3 thread. Gently, always gently, grind the M3-thread up and down the teflon couper and nozzle. This works as a very soft file. Use brass, no steel which is too hard. I have rounded the M3-thread at the bottom, so it does not damage the nozzle internally.

 

I have been using this for a couple of years now, without any problems.

 

DSCN5284s.jpg.ee251706a65b9c1ec3552398fae91c8f.jpg

 

DSCN5226b.jpg.94bfcf2cddb2f464a45d698e0c3d6bd3.jpg

 

DSCN5296b.jpg.bff580d1c16e15e32e89fdb330e78aad.jpg

 

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