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The materials have arrived a lot faster than I thought they would! The only materials left are ones that I can easily get from local hardware stores. The only reason I don’t have them already is that without a BOM I’m not sure what they are.
Only the stepper motors (4 x Wantai 42BYGHM809) haven’t arrived but they’re apparently in some sorting depot in Australia only 1 or 2 days away. You get a great discount by buying directly from Wantai through eBay but the postage stings a bit. Still $25 cheaper than local for the exact same model.
I’ll be speaking to somebody ASAP about getting the parts printed. My filament arrived yesterday…
I’m so close!
Ah cool, it’s good to know that there is documentation under development. It will take about 3 weeks for most of my parts to arrive anyway.
Besides pulling together the last of the materials from local sources and going to talk to the local hackerspace on Tuesday night I will continue making a lot of research notes.
I might be able to help with the guide. Adding a guide as part of the Lilian source would be great- use Sphinx and can have really nice documentation put up on ReadTheDocs (or whatever).
That’s kinda what I was thinking in regards to the bolts… But then again it looks like the Morgan Pro 2 is doing something to that effect so I assumed it must work. Having a large round shaft like the copper pipe makes sense for stability.
So am I on the right track with the press-fitting of the copper pipe? If I have 15mm OD pipe I guess I might be able to have it press-fit within a 6802 bearing for use in lilian_joint2. I don’t have enough experience press-fitting to know if the pipe will grip or not.
Are the lips on either side of the “inner pipe cavity” of the lilian_joint1 meant to hold the copper pipe with friction via press-fitting the joint onto the pipe? Is the pipe meant to press-fit inside of the bearings used for lilian_joint2?
I think I can easily modify the source to have small holes suitable for M4 bolts rather than pipe but I’d like to try to build Lilian as designed first using the pipe for joints and not having to modify the source significantly.
Ha, looks like I’ll do an interpretation of the Morgan Pro 2 arm assembly most likely!
But I do like low cost and all the fittings for the other method might add up So did you put a thread on the copper pipe to fix it into the arm? That would be fun to try I guess…
When I do something that was not explained well somewhere else I always tend to do a write-up and share what I have learned with others, so a build-log will come.
Can you give an estimate as to the volume or weight of the total set of printed parts? I’d like to be able to have some idea of the actual value…
Good catches!
The smooth rods don’t have to be much longer than the lead screw do they? So in that case a 1M length would do… I definitely want clarification on this.
I would say the cabinet/coach screws were meant to be M5, because a 5mm long screw doesn’t seem useful here, but yes we still need a length.
On the first page Robert said that the first version was using copper that had a diameter of 0.75mm, and that the second version (?) was using copper with a cross-sectional area of 0.44mm²… which Wolfram tells me is basically the same diameter.
This version will have a resistance of 1.45Ohm, using 38 meters of 0,44mm² insulated copper wire (38.080055m to be precise).
The copper wire *must* be insulated, else the current would flow through the path of least resistance (the platform itself) and without resistance, no heat would be generated. Insulated copper wire can look like normal uninsulated copper but in fact it just has a transparent insulating coat on the outside. If you look inside a motor or electro-magnet you will see coils of insulated copper wire.
Mathematically (it’s really simple) the resistance is calculated as shown here in this link and you can tell the amount of power dissipated (heat produced) by using the equation for Power (in watts)… (P = I*V = I²*R = V²/R).
You bring up an interesting point about the end-stops. I am sure that they would be fine, but I can’t say for sure since I don’t have a Morgan of my own yet to observe. There are some videos on Youtube which may shed some light on this.
Although I don’t have experience printing with PLA, I know that PLA does warp on large parts. So if you print lots of small parts in the area you don’t need the heated bed, but if you print a large part it will have to be heated because over the total length of the part it will shrink and warp.
Thanks. I guessed most of this but was very unsure. I had no idea what the universal build plate was, but I guess it was the last thing obviously missing…
I’ll add your notes in.
I added that extra column to the spreadsheet. Feel free to merge it into the official.
Can you make some comment on the items highlighted yellow?
https://owncloud.ddevnet.net/public.php?service=files&t=09e3e138cb0f481e9c726764be92c8d4
I saw reprap.org/wiki/Adapto#RP_parts and noticed the additional column in the table: “looks like”.
This would be a nice addition, as the picture is really useful for people who are just getting started or know something by a different name. Obviously getting all those pictures would be a fair bit of work.
Instead of playing with lacquer and screws to adhere the copper, what about just sticking them down with a large sheet of Kapton/Polyimide tape? I just purchased a 33m roll of 200mm wide tape for $20AUD – and that means it can stand temperatures up to 280 degrees Celsius. I guess you could probably use smaller width tape (say 20 or 50mm) and knock the price of the tape down to $5 + postage. The advantage of the screws is that it would make is easy to keep the wire in a neat arrangement while you stick it down but I think it could be done without the screws by keeping the wire in-place with a small amount of tape as you do each bend.
I admit I have no experience with the tape, so I won’t be surprised if I am totally wrong.
Slicer software generally expects a rectangular build area. Is the solution to simply set the build area to be a rectangle which is the same width and depth as the semi-circle and be careful not to place parts in ways that would put them over the edge? I’d probably just stick to a rectangular build platform to deal with this problem. Besides, cutting the plate in a nice semi-circle may be more trouble than it’s worth (but it looks awesome!).
Well. I’m pretty impressed.
I assumed that the weight of the arms would just be a matter of tweaking in-fill.
Can’t wait to get the cash to start building my Morgan. Pity we can’t print the expensive electronic parts…
Just from watching the videos I was also surprised, as the pictures didn’t really show off the stability that is already there.
I have been thinking about things that could be done to the arms themselves to make them more stable but I’ve not come up with anything interesting besides adding a third arm to smooth out fast motions and stabilise at long ranges.
One of my biggest concerns is the head not being level on the Y axis. (Y? Straight out from the drive shaft, I mean). The further the arms extend out the more they act like a lever that the print head can pull down on.
The concerns I had about inertia carrying the head too far can be (and probably are) addressed in software by simply telling it to slow down before the destination! So I guess I shouldn’t worry about this.
