Thanks for this thread - I am now too drooling all over the idea to have this in/on my UM2.
- stringing non existant
- retraction too fast to see
- easy filament swapping
- no more pieces of filament stuck in the bowden tube
- no more weird orientations of filament to fit the extruder/bowden tube entry
OH HELL YES!
Recommended Posts
Top Posters In This Topic
22
12
9
8
Popular Days
Aug 27
9
Feb 5
9
Aug 17
8
Aug 22
8
Top Posters In This Topic
foehnsturm 22 posts
BasVanDeursen 12 posts
chopmeister 9 posts
pm_dude 8 posts
Popular Days
Aug 27 2014
9 posts
Feb 5 2015
9 posts
Aug 17 2014
8 posts
Aug 22 2014
8 posts
Posted Images
chopmeister 0
Well, first a not-so-small disclaimer: I live in Croatia, so I cannot source virtually anything locally. Which means shipping, import taxes, VAT (an insane 25% here, which is paid for the postage price also, which in turn is twice as insane) and of course, waiting a long time for any single part. That's what makes the whole thing very expensive for me. For someone in the US for example it would probably turn out relatively cheap.
Worm gear sets are pretty costly and not all that available. I currently use the Modelcraft 1:20 set from Conrad which is around 13 Euro, and the only thing I could find, but the worm is a 4mm bore so it needs to be machined to 5mm to fit the 5mm NEMA11 shaft, which is some extra money. The motor will set you back for around $20 + shipping and taxes.
Also, since the current needed for a motor like this is pretty low, I found they work cooler and more reliably with a dedicated low current driver like the DRV8824.
I found that the best way of designing a drive bolt for this is to integrate it with the shaft which holds the worm gear - makes for a much simpler and more reliable setup, also easier to assemble. I never managed to find a local shop who wanted to do this, so I had to source them from Germany which cost pretty much, although the quality is outstanding.
And lastly I burned through kilos of filament for this thing, the thing in the photo is something like the 40th iteration. I have 2 shoe boxes packed full of prototypes, haha. There are three main versions I made with different gear/motor orientations and the rest of the prototypes branch from those. All of them work but I'm still not 100% sure which one is best.
The extrusion quality is good, and on some prototypes plain awesome, but currently I'm waiting for new belts since the ones I have are completely worn and as soon as I get them I will try to post some tests. It has good extrusion speed, stringing is nonexistent and retraction is almost too fast to notice.
The weight of the completely assembled extruder is currently around 180 grams which is pretty good, but I'm working on making it much lighter still. The last 20 iterations of the extruder mostly printed themselves out, since I have only one printer, but due to all the modifications I did to my printer over the years it's all messed up from a hundred (dis)assemblies, so it's not really a good benchmark. I hope the new belts will make a difference here, and I'm planning to make a whole new frame since my original one looks like swiss cheese ATM.
When I started with the flex shaft extruder the whole thing was only 4x4x3cm (most of it hollow), but as soon as you have to stick a motor in there it gets much more complicated if you want to keep it small.
All in all I'm due a very long blog post about all of this, but just can't find the time. If there is more interest in this, I'll start a new thread, to keep this one flex-shaft oriented. And sorry, I talk too much when provoked.
Link to post
Share on other sites