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I’ve been toying with the idea of a dual head Morgan while waiting on parts. So far I’ve made some simple sketches of a micro-adjustable 2nd hotend holder:
Simple dovetail arrangement with a “lead screw” for setting height.
I decided to do a mock up with duct tape and 2nd holder and had forgotten that the 2nd toolholder would “orbit” around the 1st and would require more than a simple X Y offset to run :O
Any input on this? I’m not sure how slicing programs handle second extruders but I imagine it’s with an X Y offset so this scheme would require some IK voo-doo which I don’t have the skills to deal with.
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Thanks Q!
Are you referring to position “A” or “B” or do I have it all wrong?
I was thinking about just another bowden tube for the second head. When not in use it could just hang out unused and the 2nd head could be lifted a couple of MM to keep it from bumping the part.
I didn’t plan on getting into this now but I’m set up with ABS now so I figured it would be a good time to print a dual head. I much prefer PLA but I figured I’d fool with this a bit while the spool is loaded \o/
Not a huge fan of re-inventing the wheel so I think it’s best to keep with the part alignments you had in mind!
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The heads will need to be on the Psi arm arch, so position B would be closer to the truth.
The main issue would be the angle offset required to make it work. The unused head would just go along for the ride. Driving heads up and down would be problematic – the idea is to limit the amount of moving parts to as few as possible. Less moving parts, more reliability
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Thanks Q, I wasn’t talking about any fancy mechanism for driving the 2nd head. The plan was to use the dovetail adjustment to raise it up a hair for single nozzle prints. Just turning the screw a few times and tightening a “gib” screw on the side to hold it up and out of the way.
Did you have a particular angle in mind or have you worked on it any?
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LOL, I need to organize my work space as well. It’s quite a disaster! The important thing is that you are at your post \o/
I’m held up on Morgan while waiting on parts but the other printer is busy printing parts for other printers so some other folks can go down the reprap rabbit hole! Prusa variants and deltas seem to be the hot thing in my little circles… That and printing in exotic materials, which I have little desire to do.
Screw compressor sounds neat! I’m familiar with them and 3d printing will be a great way to make the rotors! Suckers need to spin fast don’t they? Then I guess it’ll need a reservoir…
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Screw compressor sounds neat! I’m familiar with them and 3d printing will be a great way to make the rotors! Suckers need to spin fast don’t they? Then I guess it’ll need a reservoir…
I think they have to rotate quite fast, but that should be no problem with an e-motor and a little gear. The reservoir can be printed too. I think the pressure needed for the air-bearings should not be too high, so a printed reservoir will do the job. 🙂 The design of the rotors is a bit tricky, but I think I’ll get it within this week. Later on I will have to experiment with different sizes and rotation rates to get the optimum.
I hope my workplace at home will get ready this weekend to conclude the work on my Morgan and start printing. But maybe it will take more time I’d like it to. Whatever. It takes what it takes and it is a pleasure to do this project and to share it with you all.
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Here’s some initial doodling on the main toolhead:
Figured since I was fooling with it I’d go ahead and change it to accept a push fit connector. I have a 1/4″ BSP X 4mm on my other printer which works well.
Still need to make sure the angle of 2nd head is going to be correct. I’ll probably print one out and check it with a sharpie pen or something.
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Went ahead and printed the parts to see if it’s workable:
I didn’t finish printing the 2nd holder because I was just going to test the slide mechanism. So far I don’t see any problems with it at all \o/ I printed the female part with support which was a bad idea because it had to be picked out but after some filing/honing the slider is tight and remains “in plane” when slid up/down. I’m not even sure if a screw in the side will be necessary because the sides of the female part grip the male part pretty snugly. I’m guessing that the “lead screw” may be enough to hold it in place.
The way it is now it has about 8mm total adjustment.
I guess now I need to work out the correct angle so the 2nd head will follow the first along the arc.
Something weird happened with the toolholder stl you have posted on your wiki page Robert. I didn’t notice until after printing but the “facets” that mate with the arm are too wide as is the hole spacing for the carriage screws. I thought it may have been my toolpath gorking things up but it appeared the same in sketchup, netfab and cura. I tried Q’s original stl and it looked fine. I grabbed the stl from your page because the pics make it easy to choose parts 😀
Here’s what I mean:
Probably something I’m missing but you may want to check it out.
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I would check it out closely Robert because there may not even be a problem with the files. It could just be some of my importing/exporting/manipulating them made things wonky :O
Any input on the “slider” mechanism Q, or did you have something else in mind or see any obvious problems?
I believe for the next version I’ll attempt to get the distance between the 2 nozzles as short as possible while still clearing the arm that the bearing is pressed into. May need move the adjustment screw to the bottom…
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It looks better than I could imagine. The picture on the smartphone does not do it justice. Yes, I would place it a bit closer. Perhaps also work out to position of the hotend so that it is not 90deg to the arm, but on the arch of the circle formed by the secondary arm at the elbow.
I’ll see if I can import your idea into the openscad code.
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Fooled around with some sharpie pens to get an idea of what’s going on:
The plan was to pick up the proper angle but I neglected to take into account that the distance between nozzles would change it 😛
I now believe that a “hinge” mechanism to adjust the angle will be necessary. If the location of the hotend is off by the tiniest bit in the holder it’ll be amplified at the tip of the nozzle and the layers won’t be aligned. It may be workable without an X/Y hardware adjustment but the parts would have to be really precise.
I was thinking about some type of micro-adjustable screw deal on “hinge” for allowing precise adjustments but it would complicate things…. Maybe just print a pointer and some index marks?
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I am making a new single piece toolhead with two hotend mounts. What is the thread type of your push fit adaptors.
The way to get the angle right in Openscad is simple and effective. I am going to try one out tonight.
Hight adjustment could be done using screws from the top. I will send some pictures when I am done.
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Awesome Q!
The ones I have are 1/8″ BSP but they are available in metric as well. I’m using 4mm OD for the bowden tube.
Like these:
http://www.ebay.com/itm/250530953411?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
They are one of the best modifications I have done to the bowden setup on my rostock!
I cooked this up earlier:
But it’s suffering from feature creep overcomplication…
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The best way to mount the two heads would be next to each other on the arm. That means that the offset would be only a Theta angle offset between the two heads. It would require some extra work on the firmware, and a clever way to pass the filament to the heads, but this is what I plan to do with Lilian.
Current Morgans will be upgradeable to the dual head models by simply printing new toolheads, and adding the extra extruder.
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Dahhh.
You want me drawing your ideas, don’t you? 😉
Hm. So sorry that I’m too busy at the moment to help you with that. I’ve posted some new drawings in the RepRap-Wiki, e.g.an advanced design for an air-bearing-z-axis and an assembling instruction for the leadscrew nuts (Steve requested that).
Actually my progresses on my real morgan get a bit stuck, due to the need of reorganizing my lab. I’ve got only little space for my work and chaos was becoming overwhelming the last weeks. So I decided to reorganize first and then finish my work on my real Morgan (I need to connect the electronics and upload the firmware).Being able to invent and draw while I’m at work in the office (where I, too bad, can’t work on my real Morgan), I found an interesting solution for a printed air-compressor, that will be needed for my air-bearing-ideas. It will be a screw-compressor. This technology is used in big compressors for > 30PA but can be downsized very easy (nobody tried until now though). It will deliver a continuous,powerful robust air-stream while being very silent and energy-efficient. The calculations and drawings are a bit complicated but worth the effort. The compressor itself will be very simple with very few moving parts and therefor only very few vitamins (4 x 608 bearings, a small cheap motor, rest printed). Not too expensive, I guess.
So, I really am too busy for further tasks at the moment. 😉
But I’ll keep it in mind and provide help as soon as I can. -
Thanks Q and sorry for the poor picture. It’s just a sort of proof-of-concept right now. I need to sit down and figure out the proper angle that head #2 needs to be at for it to properly “follow” #2 around the arc. If you work it out please let me know.
I had considered making the “little arm” on a simple hinge with a single 3mm bolt so it could be adjusted to follow properly. That would give one hardware adjustment plus changing a value in firmware for calibration. That and leveling the 2 nozzles…
Perhaps a calibration routine that would print along the arc with nozzle #1 and then follow on top with a layer from #2. That way the 2 heads could be synched along the arc with the hinge adjustment and further tuning could be done via a firmware offset.
While I have no experience printing with 2 hotends I believe that Morgan is the best suited design for it \o/ The fact that all of Morgans extrusion bits are up top rather than buried within the machine should make the tweaking necessary for getting it (and keeping it :O) working a lot easier!
I sure wish my parts would come in so I can finish the machine instead of coming up with hairbrained ideas 😛
Oh yea, I just wanted to add this:
I’m using these push connectors for the bowden setup on my Rostock and they work pretty well. It does add to the vitamin count which I’m not a big fan of but there is always the option of using the printed bowden retainer which I think looks waaaay better anyway!
These may be a better option for a dual-head just because of clearance issues and the possibility of much fiddling while setting up… May also be useful for your air bearing setup as well Robert.
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