Yet another buildlog

Yet another buildlog

Postby NeoTheFox » Wed Jan 29, 2014 9:58 am

Hello to everyone. My name is Nick, and my university recently got professional 3D printer, but only one for the whole university. The printing speed is super-slow, and it uses really crappy software (no g-code, no chance to make own route for extruder, and crappy proprietary algos for filling). I have a full access to it, and I decided to build a RepRap machine for our lab, and maybe for some other labs lacking 3d printers. Simpson family really got my attention, so I decided to build GUS and LISA models, starting with GUS.
The main problem is the lack of materials (it is hard to translate US specs to ГОСТ, so I am working on this). The deadline for me to build a working base (with no extruder and hardware just for stepper control) is 16 February, so it is kind of extreme challenge :)

I started working 3 days ago, printing smaller parts
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This printer messed up one of the bigger parts, but I belive I can still use it:

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I was very worried about the screw, because i expected it to mess up again, but it worked out to be nice

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While I am writing this post, the rest of HUB is being printed. I expect it to finish at night, and after this I would be able to proceed on Monday, so the rest of the time I will be searching for vitamins. Bearings and spring are going to be a pain in the ass for sure. The rest of the parts (Slave arm and motor arm) are going to be printing for 64hrs, so all the gears makes me nervous, I hope it will not mess up the parts like it did with last one.
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Re: Yet another buildlog

Postby Guizmo » Wed Jan 29, 2014 2:34 pm

Hi, welcome to the forums!, very good progress!

If you intend to print with the machines ASAP, I'd recomend building a LISA first. I'm not an expert on it, but AFAIK is the more accurate of the Simpson family and I bet is the simplest to build. GUS just needs more work, but he is a good guy ;) .
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Re: Yet another buildlog

Postby NeoTheFox » Wed Jan 29, 2014 4:48 pm

Guizmo wrote:Hi, welcome to the forums!, very good progress!

If you intend to print with the machines ASAP, I'd recomend building a LISA first. I'm not an expert on it, but AFAIK is the more accurate of the Simpson family and I bet is the simplest to build. GUS just needs more work, but he is a good guy ;) .


Thank you for the good words, Guizmo!
Building LISA first was the original plan, but 7_16 TORQSPLINE is something you cant find in my country, and buying it from ebay is not an option due to time limits, so GUS will be first
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Location: Moscow

Re: Yet another buildlog

Postby Nicholas Seward » Wed Jan 29, 2014 6:07 pm

You can use other screws. See what large pitch options that you have locally.
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Re: Yet another buildlog

Postby NeoTheFox » Wed Jan 29, 2014 6:44 pm

Nicholas Seward wrote:You can use other screws. See what large pitch options that you have locally.


I really doubt I could find something with this thread. Here is the list of threads I can buy (except for the last one):
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There is no standard like this, so my only two options are modify STL's for another thread (and if I would I will fork LISA and adopt whole thing to ГОСТ-friendly element base), or order it online. I've been thinking about this one already, the idea was not to touch threads, but do something tricky - split the screws in 3, then join it together with a smaller metal screw inside. I can pause my 3d printer, so I even can make a nut-shaped hole somewhere near the end of one piece, and place nut there while printer is paused. I also fought about ordering screws with such thread from a mill, but these guys are slow as it gets for retail orders. Anyway building GUS is really least complicated for me right now, I have been in a hardware store, and I found bearings! Spring apart, this was the main trouble I've expected, and it is solved now. No luck with spring yet, however. I also think I'll print a tube to cover thread on M8x55, because I could not find bolts with partial thread.

Thank you for being supportive, by the way.
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Re: Yet another buildlog

Postby Nicholas Seward » Wed Jan 29, 2014 8:10 pm

The string goes around each bolt twice and the speed that the string goes over the bolt is different between the two. That means you have to have 2 printed sleeves/bolt or you have to have sleeves of some material that string won't eat through like a saw.
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Re: Yet another buildlog

Postby NeoTheFox » Fri Jan 31, 2014 1:41 pm

My search for Vitamins is almost over - I've found bearings in RC store, and I have found partial-threaded bolts.
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It is all about 6702 bearings and springs now, I've ordered springs at the mill, because I failed to find anything even remotely like it.
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Re: Yet another buildlog

Postby NeoTheFox » Sat Feb 08, 2014 11:44 am

Image

Now I have theese, Slave arms coming up!
When top plate and bottom plate would arrive I will be ready to build it! I'll try to make many photos to describe building process if it would be possible.
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Re: Yet another buildlog

Postby NeoTheFox » Wed Feb 12, 2014 4:05 pm

Today was a busy day, the parts just finished washing up and I started my build. First of all - the damaged part have been damaged too much to use it as it was, after support washed out I figured out the bearing hole was oval and partially blocked by the lump of plastic. Since I had no time to print it again I tried and carefully removed all the extra plastic with a knife and tried to shape the part as it should be, but the fact it have been oval made me cut too much from the edges and this resulted as a two cracks when I installed the bearing. Even worse - it is not really upright there, so this part would need a replacement, since it would cause errors and it WILL crack eventually. Lets hope the big day will not be spoiled.

Our Lab works only till 18:00, so I've been forced to stop working. So far I've assembled the base and one arm, however I believe I did something wrong with stringing (I think I forgot to made a few turns over the pulley), this resulted in string not rotating motor when arm is being opened, but to go straight through the pulley hole. Turning the pulley by hand only result in extreme stretching of the spring, so I'll have to redo this, and also replace threaded M8x60's with partially threaded.

Right now I am looking for a temporary engine control solution to make it work with no Azteeg, since it failed to arrive in time. I made a quick arduous-based prototype based on L293B, and I am going to assemble it tomorrow. If someone wants me to I can publish PCB and source code (it will be very simple).

While it is not even half-assembled yet just the glance on it gives me chills, this machine is really beautiful piece of art, unlike many other RepRaps, thanks to Nicholas.

And here are some photos (I hope there is not enough of the lab on thees, because posting lab pictures can get me into trouble :| )

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Location: Moscow

Re: Yet another buildlog

Postby Nicholas Seward » Wed Feb 12, 2014 4:38 pm

That is exciting!

What kind of printer are you using? Dissolvable supports?

To insert bearings, I heat the bearing and the plastic in an oven at the lowest possible setting. For me it is around 200F. I pull the part out every minute and try pressing in the bearing. If I have to struggle at all, back into the oven. This process is very forgiving to bad prints.

Note: Without a very precise printer or a lot of careful sanding, it is very hard to insert a bearings cold without cracking the plastic.
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