January 14, 2016 at 20:11 #6387
I am looking at building a Lilian and I noticed in the picture of Lilian and in the scad file that rod (the same size as the drive shaft rod) is used in the driveshaft arm mounts.
I don’t understand how the rod is actually fixed in place. I also don’t understand how the pipe is held in the arm bearing mounts either.
I notice that the Morgan Pro 2 doesn’t use rod for the arm mounts but rather a more traditional system of bolts, nuts, washers, bearings etc.
Would I be correct in following the lead of the Morgan Pro 2 pictures rather than worrying about the magic shown in Lilian.png?
Can we develop a Lilian BOM?
January 14, 2016 at 21:06 #6388
The Lilian in the picture is an extreme low cost version of the Morgan Pro 2, in that you use 15mm copper pipe in stead of machining the drive rod or the arm hinge mounts, and all the plastics are printed rather than manufactured in a factory. The bearings are press fitted (needs a bit of work with a wood block and a mallet to get it installed.
Of course, when you build it you are welcome to interpret it as you like… That is a common occurrence amongst those brave enough to build a Morgan from scratch!
January 15, 2016 at 02:53 #6389
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.
January 16, 2016 at 12:23 #6391
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.
January 16, 2016 at 12:30 #6392
M4 bolt is not quite sturdy enough to hold the arms stable during printing. You need something with a larger diameter. I found using M8 bolts with 608 bearings did not give the right amount of stability either…
You are welcome to modify away. Just remember that most of the design choices was paid for… in failure 😉
January 16, 2016 at 12:52 #6393
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.
January 16, 2016 at 14:15 #6394
Press fitting involves driving the bearing over with a hammer…
The new guide will be ready in three weeks, after we completed the first build course. It is always hard to write a guide before you know what to tell people…
I will start publishing sections of it soon.
January 16, 2016 at 14:19 #6395
Morgan 2 has machined hinge joints with 15mm OD tips for the arm printed sections. The bolts just keep it together.
January 16, 2016 at 14:44 #6396
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).
January 25, 2016 at 15:28 #6400
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!
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