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3poro

3poro's comeback, featuring Pololu's death

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Hello. Long time, no me. I've been fighting on other frontiers... Every now and then I've been printing bits an pieces, but nothing ambitious at all - partly because the performance of my UM2 was compromised. For Xmas gifts, I printed some Xmas trees and I used Formfutura's "glow in the dark" ABS - which turned out to be very abrasive:

nozzles.thumb.jpg.c59363851afd108689ce6281884563f6.jpg

The block I had on my printer didn't produce very good print quality anymore. I knew I should have simply changed the nozzle, but I pushed the thought back as I guessed I would have to re-make my self-made temperature sensor. When I inserted it to the nozzle block several months ago, I realized the fit was a bit too tight. Now, when removing it from the nozzle block, it didn't come out in one piece. I should have thought about it before. To the new nozzle block I drilled a hole for pushing the temperature sensor out.

Okay, so I took the time to change the nozzle and re-make the temperature sensor - and I managed to get a few nice prints out from my UM2. Then, I started having under-extrusion problems... nostalgic feeling, or something. After "some" troubleshooting, I realized the problem was in the stepper motor - or its driver. The torque just wasn't there anymore. Maybe it's me to blame - I have used the extruder stepper motor with 1.5A current. Maybe now this practice took its toll:

broken_Pololu.thumb.jpg.581f1dd47a2213e8fc67580da12a84e6.jpg

Great - so my UM2 motherboard needed changing. But wait - there was a reason why I felt I had to use the 1.5A stepper motor current - and even that didn't feel to be always enough. Before my UM-break, I had already ordered this kind of stepper motor:

http://www.robotdigg.com/product/29/Nema17-60mm-1.5A-high-torque-stepper-motor

But, if the standard stepper motor can be too much for the Pololu driver, probably the new stepper motor would kill it even faster? So, my UM2 motherboard needed changing but even that wouldn't have satisfied me. I decided to bypass the dead Pololu altogether and use an external stepper motor controller. I decided to try to make it in a way I wouldn't need to make a custom firmware - so, I had to remove the dead Pololu:

removed_Pololu.thumb.jpg.eb11a35e65ce325a5134d4fce8e01f17.jpg

...and bypass it:

bypassed_Pololu.thumb.jpg.4e8b0ee364baa5bc4182f3677b03e33b.jpg

The contrast on the picture is a bit misleading - the board looks more clean to naked eye. Most importantly, the hack works. Now the critical digital outputs (pulse, direction, enable) are taken out from the UM2 motherboard to an external stepper motor controller. I happened to have an M542H stepper motor driver waiting to be used - so now I have a lot of headroom in case I need an even more powerful stepper motor for my extruder :)

I decided to use the existing extruder connector for the digital outputs - so I have to remember not to plug a stepper motor directly to the connector anymore.

I really need to catch up with Anders Olsson's work, the original UM2 heater/nozzle block has caused me too much headache...

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Holy mother board! I was dealing to make a proper fan for my board but after seeing this I wont delay it anymore! Btw nice hack

 

Thank you! Actually, I started to think about cooling for the motherboard as well. The circuit board around the stepper motor drivers for X and Y axes had yellow/light brown tint - so the temperatures must get pretty high.

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Nice to see someone start hacking away on these all too shiny and new UM2 printers... Seems people in general have been reluctant to mess too much with them, compared to the UMO printers and boards.

Maybe its because they have just worked (at least up until now) or maybe its the price tag and Apple look, I dunno...

anyways, congrats on a hack well done :)

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A little late at the party, but great job!

Did you install the Olsson Block as well?

With your own temp sensor?

What are those things on the back, above the power chord?

That is one awesome looking Ultimaker you made! :D

I am curious to see what you are going to print, which 'justifies' these hacks. (besides no head aches (that is a referral to the closed frame and your hot end problems) ;) )

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Hello Sander!

The boxes above the power cord are (from the top) the M542H stepper motor driver and a no-frills 24VDC power supply. The latter is powering the new stepper motor as well as my print head fans (front + rear).

Here's my latest print, an enclosure for a quite simple electric device:

enclosure_parts.thumb.jpg.3db564b0ae637f0fdad257f315b267c8.jpg

enclosure_assembled.thumb.jpg.2d30006dd6d33517ed335387fadf65aa.jpg

These specific parts don't have any tricky overhangs or otherwise challenging structures, but to get them printed some mods are vital. Warping has to be eliminated completely and layer-to-layer adhesion has to be really good. I'm very happy with the results: the feel is very solid.

The Olsson block I haven't tried yet. The UM2 original nozzle block serves me quite well - it's just quite a pain to replace. One more photo of my UM2:

front_view_201508.thumb.jpg.2a721fd39fc96db1c2a9524e62bd83ae.jpg

enclosure_parts.thumb.jpg.3db564b0ae637f0fdad257f315b267c8.jpg

enclosure_assembled.thumb.jpg.2d30006dd6d33517ed335387fadf65aa.jpg

front_view_201508.thumb.jpg.2a721fd39fc96db1c2a9524e62bd83ae.jpg

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