Sunday, May 12, 2013

Progress on the right hand and arm.

Right hand and forearm

I have been working on printing the right hand and assembling it with some test strings to test the finger movement. But first a few of my minor disasters. In the process of assembling the fingers, I broke a lot of connecting tabs. After fighting with the printing process I figured out that printing the fingers with solid infill for every layer made the fingers much stronger. After re-printing all the fingers, I had no more broken fingers.

 Some finger bits - both broken and unbroken. I couldn't find any more of the broken pieces. Last I saw then they were flying across the room.

The right hand assembled and with some test strings to test the finger movement. It's kind of a tricky process getting the strings down through the fingers. It helps a lot to have some good tweezers like in the InMoov blog photos.

The beginning of the assembly of the right forearm and wrist. I had some problems with the printer so it produced some parts that were a little bit warped. I decided to go ahead and assemble the arm as best I could so that I can get one assembly that I can start doing some software testing. I will redo the forearm and wrist later on to get a better fit of the parts.

Some more of the parts of the forearm to be assembled. The printing process of the rest of the wrist is still going on.

Some 3D printing lessons

In the process of printing the parts for my InMoov I have encountered and solved a few problems. 

Broken fingers.
    I mentioned this above. Printing the fingers with solid fill on every layer helped tremendously.

Warped parts.
    The problem here was that the parts were not sticking to the bed very well. I am printing on a heated bed of Kapton tape on glass over the bed heater. I had many sticking problems until I started using a little bit of a mixture of acetone and dissolved pieces of abs plastic spread very thinly on the Kapton with a q-tip. This changed a sticking failure into a problem getting parts unstuck but they come out much better.

Extruder/frame collisions.
    Several of the forearm parts are quite large both in X axis and Z axis. If you are using this type of printer, i.e., a linear prusa ( or a printer that has about 100 - 110 mm of Z axis space ) be careful that the extruder is not going to hit the top frame. Also, one of the arm pieces I printed was wide enough and the default start location for a print was 100, 100 such that near the top of the print the extruder was hitting the frame on the right hand side. Needless to say this print came out a bit funky. Check that the width of the item to be printed is not wide enough to cause collisions.

Anyway, the arm/wrist printing continues and I hope to have the arm together and functional soon.

Friday, May 3, 2013

Finally a start on my InMoov

Printer arrives!

My printer arrived about a week ago and I proceeded to assemble the little guy with a lot of help from the MakerFarm assembly docs and videos. I also had several help sessions from Colin at MakerFarm. I must say that I would have been completely lost without all the help.

Anyway it is together and printing most of the time. Still a bit of an adventure but worth it. Here's a couple of pics:

It is a linear bearing Prusa from MakerFarm. Rat's nest of wires I still have to straighten away.

Here's one from the other side. It is currently printing the large wrist piece for my InMoov. It can't be seen because the extruder is hogging the camera.

This shows some more of the clutter in my work room including the filament spool up above.

Beginning to work on my InMoov.

I have gone through the process of printing out the pieces of the test finger, assembling it and writing a simple Arduino sketch for testing. Here's a picture of the finger and my idea of a 9 volt power supply.

and a little video with the finger fingering.


Like the nail polish??

I am currently printing out the pieces of a right hand, forearm and rotating wrist in anticipation of assembling the first part the my InMoov. Also, work is underway on a control program for Raspberry Pi that I am writing in 'c'. I will be using Adafruit's 16 servo control board and one or more Raspberry Pi's.

I must say that I am having a great time. I just need to find more time to blog about the whole process.