Printable Useless Box with GM3 Motor

by jamesarm97, published

Printable Useless Box with GM3 Motor by jamesarm97 Mar 22, 2013
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When I first saw this box online I had to make one. I used what parts I had on hand. The motor is a GM3 geared dc motor. The motor mount was designed for it along with the arm. Two led's were added with fiber optic going up to the finger tips.


Update: Uploaded the arm modified for the GM3 but it does not have the end modified yet. I just cut off about 1/2" of the end and superglued the hand on. It will be modified soon with the correct length so the hand can just be glued on.


Print either the Fullsize box (for large bed) or 1ea of the Box_SmallBed_Left and Box_SmallBed_Right. This is the bottom part of the box.

Print the Lid_SwitchSide and Led_ArmSide. The switch side is where the DPDT switch goes. I had to drill the hole out a little to fit a Radioshack switch I used. The indentation on the bottom of the lid is for the keyed washer from the switch to keep it from spinning.

The GM3 Support Bar was designed to hold the GM3 Geared motor. It screws into the two support blocks on the box bottom. 6-32 screws were used to hold it in. The GM3 gear box was screwed to the bracket using a couple of 4-40 1" screws. There two sets of holes, only one of them are used.

I used a Radioshack limit switch with a roller on the end. It mounts to the Limitswitch mount with one screw (2M or 2.5M screw I think). You can change the angle of the limit switch a little to adjust when the motor stops. I superglued the mount all the way against the arm side of the box centered so the arm would hit it. There is a photo showing where.

The Motor Arm Spacer was used to sit between the arm and the gearbox. There was a little gap because of the protrusion on the GM3. The flat side go towards the arm and the recessed side go towards the gearbox.

I had to print the had without cooling enabled in the plugin but turned down the speed. If I didn't the fingers got too hot from the hotend sitting in one spot too long. You will have to experiment with your setting. The hand was superglued to the end of the arm.

The Arm has two holes for rectangular LED's (from radioshack again). I used a green and red led. I drilled a small hole from the other side to meet the opening and used this to glue in fiberoptic. You could skip this step. The led's were glued in and the power leads were wired so that one led is backwards from the other. This way one lights when the motor has forward power and the other lights when the power polarity is reversed. You can look at the original project for a drawing of how the motor and wiring works.

The arm was secured to the motor with a small self tapping screw. Everything was put in place then I turned the arm until the lid shut and then adjusted the limit switch so it just clicked. The motor runs for a split second after it is turned off so I adjusted it to turn off just as the lid cleared and have about a 1/4" of space once it turns off between the hand and the bottom side of the lid.

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The full size box and the right small have this "T" part in it that is hovering above the bottom surface. I'm not sure what it is there for but you should remove it or have it attached to the box. Also It's not in any of your photos just the part pictures.

the hand file isnt downloading correctly

Try Save as. It was opening in my browser as text for some reason although most of the others would download. I have seen that before.

This is a really nice execution! Would it be possible to post the CAD file(s) soon? I'm sure there are a lot of people (myself included) who would love to have access to them. Thanks!

Files coming now. The only one not uploaded yet is the arm. I had to cut off the end because of the angle and that is when I decided to attach a hand on the end. I will change the cad file to have the right length. The hand is already uploaded. I just superglued it on.

HA! I loved the red (angry) and green (happy) LED through the arm/hand! :)
That is a really nice touch to it!

I might see if your arm will modify to fit a hacked servo & lasercut version from Thingiverse - i made one of those.

Yeah, it makes it. I used some cheap fiber optic from one of those lit Christmas trees and ran it along the underside to the fingertips. The last part of the video shows it best.

I hope to find time this weekend to get the files uploaded with some instructions.

This reminds me of a "piggy bank" I had when I was a kid. It was a coffin that had that same type of hand and it would come out and grab the coin you placed on top and pull it inside.

Exactly. I went by my sisters last night to get a haircut and showed her. I had the same flashback and said the same thing. I guess that shows our age.