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A different multi-extrusion approach - UM tool / printhead changer

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Hey, I've only got two spools of 1.75 mm filament right now: black and lime green :p

Yoda strikes back. Footage will follow.

yoda-strikes-back.thumb.jpg.d45a9f9021bb2f65ff6d5e363020d0f0.jpg

yoda-strikes-back.thumb.jpg.d45a9f9021bb2f65ff6d5e363020d0f0.jpg

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Very impressive prints there. Whats the next developments on this project for you foehnsturm? Have ultimaker given you a call yet to discuss a partnership!?

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Posted · A different multi-extrusion approach - UM tool / printhead changer

The project is a little delayed because of weird cross talking issues with the smoothieboard. It's only working reliable with the screen disconnected, which is somewhat annoying for testing. Don't want to start an additional project with octoprint right now. So I ordered a smoothie-compatible board from China as an alternative. When everything is working as it's supposed to, the next step would be implementing the tool changer sequences.

I'm in touch with Ultimaker but there aren't any definite plans yet.

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Unfortunately not. The guys in charge of Smoothie kindly sent me a replacement board but I hadn't the time to start over again. Busy with another project at the moment.

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Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

 

@foehnsturm I'm making a mod head assembly for the umo+ (With that pancake motor) standard and I was wondering, how did you joined that big bronce gear to the mk7, that itself saves a lot of space for the gears. I'm going to buy a pir of gears from misumi (expensive but very compact) but I can only do a 3:1 with the available gears and I'll like to know if you think that's enough to at least extrude at a normal (50-70mm/s 0.2 layer) speed. But I suppose with more heat the force should suffice.

Edited by Guest

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Posted · A different multi-extrusion approach - UM tool / printhead changer

 

@neotko you need access to a lathe. I drilled the gear bore to 8mm (I think) and machined one end of the the mk7 down to this diameter. Then it's almost a press fit.

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Posted · A different multi-extrusion approach - UM tool / printhead changer

:O I'll try misumi gears then :D

If I get a lathe my wife sure kicks me. The room it's already full of stuff already. Thanks @foehnsturm !

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Oh btw sorry to bother again, but @foehnsturm I also found a place for gears, (they don't look as neat as that website you linked but they are hyper cheap) hobbyking dot com

I got this:

25T/5mm M1 Hardened Steel Pinion Gear (1pc)

10T/5mm M1 Hardened Steel Pinion Gear (1pc)

M1 I suppose it's much worse than 0.5 (I have zero gear knowledge) but they are just cheap as chips.

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Posted · A different multi-extrusion approach - UM tool / printhead changer

@neotko you don't bother ;) I just don't have enough time atm to continue with this project. But in not too far future I'll proceed with it. M1 is ok I think if you go for modest gear reduction. As I looked 1:4 or more, gears just would become too big with M1.

There are very small and affordable (ok rubbish in some way) lathes ;)

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Posted · A different multi-extrusion approach - UM tool / printhead changer

I'll make you proud master (really I learned soo much from you!).

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Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

M1 gears are huge! This is a (module) 1 worm next to a m0.5:

20160121234835.thumb.jpg.f48a9c8295fbe0ba084ab967dd412639.jpg

The M1 gears weigh like... I don't know. 100 grams?

20160121234737.thumb.jpg.989ee1c3f4b6b17e71068880ee2312cf.jpg

I chose a 13t m0.5 gear with 5mm shaft from veroma-modellbau.eu

IIRC, that link came from foensturm in this very thread.

I didn't want a heavy steel gear, so I'm pairing it with Misumi's GEABM0.5-50-3-B-5.

Yes, that gear is insanely expensive (12.70 EUR) but the quality is great. Btw Misumi doesn't have small gears. 20 teeth is minimum, so a combination is highly recommended.

/edit:

IMG_20160211_091523.thumb.jpg.0f65861c57eaa73cb686507872801bf3.jpg

Here's the two gears. I've already mounted the M1 gears, so I can't add them to the picture. But you should get the idea: These gears are tiny. And the Misumi Nylon gear is light as a feather.

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IMG_20160211_091523.thumb.jpg.0f65861c57eaa73cb686507872801bf3.jpg

Edited by Guest

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Posted · A different multi-extrusion approach - UM tool / printhead changer

I didn't went for worm gear because I saw this:

http://www.roymech.co.uk/Useful_Tables/Drive/Worm_Gears.html

That I found thorugh this:

 

With sinusoidal micro stepping drive the holding torque will be 0.7 times the two coil on value. I.e. 0.21Nm @ 2.5A, so 0.126Nm @ 1.5A. The torque from the pulley is only 0.016Nm assuming a reduction of 40:1, so the worm drive is only about 13% efficient if I have got my calculations right. Before I greased it, it was only half as efficient, so worm gears certainly waste a lot of effort in friction. The article here says they are between 98% and 20% for ratios 5:1 to 75:1, so I am probably in the right ball park. There will also be some friction in the bearings and pull out torque will be a bit less than holding torque, even though it is only rotating slowly.

 

Quote from:

http://hydraraptor.blogspot.com.es/2009/10/worm-drive.html

So maybe for a feeder isn't the most efficient way to keep the torque?

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Baah, too much numbers for me ;) I only looked at the graph, which shows efficiency rates between 75 and 97%, if I read correctly.

If they were that bad like 13% efficiency no one would use them.

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Posted (edited) · A different multi-extrusion approach - UM tool / printhead changer

No, I wouldn't use a worm gear for the feeder either. This has been done before, though. And afaik it worked pretty well, too.

My M1 worm gear is used to drive the Z platform, which is why I went for such a huge thing :D

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Posted · A different multi-extrusion approach - UM tool / printhead changer

I've been working for a while on a derivative of the slim Extruder ...

Really great design foehnsturm ;)

It's for a big CoreXY I build at work. And maybe a second one for me :)

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5a3318ea07e72_Screenshot(18).thumb.png.1f5df73b1176c385d49864f27bc97771.png

Let me know what you think of my design ;)

5a3318e969917_Screenshot(15).thumb.png.4ccaebbaf1e759ffcbf815f51ec6780b.png

IMG_20160227_010213.thumb.jpg.77dbe1f0ec356be13989170425bfb1d9.jpg

5a3318ea07e72_Screenshot(18).thumb.png.1f5df73b1176c385d49864f27bc97771.png

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Hey great!

Does it work like intended? I would like to copy :)

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Posted · A different multi-extrusion approach - UM tool / printhead changer

That's a nice and clean design @thefrog I want to copy too! Looks gazillions better than my crappy adapter.

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Posted · A different multi-extrusion approach - UM tool / printhead changer

Haven't had the time to test it yet.

But everything goes together nicely, so would be nice if someone could confirm if it works alright.

Will upload some STL's and instructions in a minute.

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Posted · A different multi-extrusion approach - UM tool / printhead changer

BTW you need to manufacture/machine some parts yourself to make this design work !!!

e.g. the hub of the 60t Gear has to be shortened

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Posted · A different multi-extrusion approach - UM tool / printhead changer

BTW you need to manufacture/machine some parts yourself to make this design work !!!

e.g. the hub of the 60t Gear has to be shortened

 

sounds familiar ...

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Posted · A different multi-extrusion approach - UM tool / printhead changer

There's a 60T gear from misumi (or I think it was 58T) that has a inner dia of 12mm. With that you could insert the mk7 inside and align the screws so both are together in love :)

I didn't went that path because I just found out after buying my 50T :D

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