I finally found time and space to give Milford some attention.
I gathered all the parts for Milford (mill, cpu/driver stack, power supply, cords and cables) and rebuilt a Windows PC for controlling it, then I had to get software and upgrades to get it all running. But lo and behold…
Well, there’s something. The text isn’t quite right. It seems to be skipping steps.
A few more attempts – a PCB – sharpie is too thick for that print.
The beginning of this print was messed up with me fiddling with my lousy rubber-band sharpie mount and finding a good z0. But the end was skipped steps due to an overheating driver (I think). I put a fan and heatsinks on the drivers and the problem went away. The “ShapeOko” in pencil was printed after the fan was in place and it came out cleanly.
The picture on the left was before the fan and the picture on the right shows the image without skipped steps after the fan was in place. Quite a difference.
Something changed in either the machine or the plastic because of the increased humidity. Apparently I need to run the plastic hotter than before. The filament got jammed in the print head so the hobbed gear was tearing up the filament that couldn’t go anywhere. It heated up to the point of melting. Here’s a pic of melted plastic along the Makerbot drive gear.
After disassembly for ease of cleaning, I popped the piece of plastic off and used a toothbrush to clean the drive gear. Hopefully that’s all it’ll take.
(later…) No, that wasn’t all it took. The print head was really jammed and had to be disassembled and cleaned. Now it runs well.
I printed this out quite some time ago and was waiting for an opportunity to install it. It’s a cover for the Arduino and shield in the Makerbot. It replaces a pair of spacers (which go right into the parts bins).
I also took the opportunity to hinge the electronics platform. I was inspired by this Thing 16796 some time ago. I used different hinges and didn’t do proper calculations of hinge hole locations and kinda just bodged it up. But it works fairly well and allows opening and closing of the bottom panel with removal of just a few of the motor driver hookups.
The wires to the steppers don’t have a lot of play. They may not even make it to the controller. So I’ve got to add some length. It’s relatively simple task, but it takes awhile. There are a lot to do, so you can get into a rhythm. I usually forget to put the heat-shrink tubing on before soldering connectors, but the ends of these extensions do not have connectors so you can slip the heat-shrink on after soldering.
Maybe I went a bit overkill on the wiring gauge, but I use what I’ve got. I put some wire weave on the Z stepper wires, as they were free. The X and Y steppers were already sheathed.
On the controller, I’m using the A-axis for the second Y stepper. I tied the step line together so they should step together. I wanted to use the same driver for both Y steppers, so I’m using a step-stick driver in for Z.
For a recent 4-H project, I decided to have my kids make a simple motor.
The project uses a derivative of battery holder that I created and modified to make into a Continuity tester for an earlier project. The item is Thing 18354.
The first step is to take about a 2″ piece of stripped, 22ga solid wire and make a single coil in order to hold the rotor. Do it twice. These will support the spinning rotor and conduct electricity to it.
The next step is to use a small gauge wire to make the battery contacts (see the side of the holder here, and refer to this earlier post for more detail).
The new thing has slots in either side to hold the rotor arm supports and make contact with the battery (without soldering). Make sure the battery contact wire is pressed well against the rotor arm support on each side. Put a battery in and use a multi-meter to make sure that the contacts are providing electricity through the rotor supports.
Glue a permanent magnet centered onto the top of the holder. I used powerful, thin, Neodymium magnets.
Now we make the rotor. Take about 3 feet of enameled wire (motor wire/magnet wire) and coil it up around a AA battery. Leave a few inches on either end to use as the arms.Wrap the end of the wire around the coil to hold it tight. Try to ensure that the free end of the wire is straight and centered on its’ side of the coil.
Once the coil is complete, hold it against a surface, like the edge of a table or workbench, and scrape a bit of the enamel off of the wire. Be careful not to scrape too much off. It needs to be 1/2 of the circumference of the wire or less. Do it on both sides. (The pictures just show one side.) If done correctly, when the coil rotates, the exposed part of the wire will touch the rotor supports and allow electricity to pass through the coil, making an electromagnet. This will cause the rotor to spin and pull towards the permanent magnet or push away from it.
Insert the coil into the rotor holders. The rotor should spin freely and sit closely above, but not touching the magnet. You can bend the ends of the wires a little or use beads to make sure the rotor doesn’t move too far back and forth and slip off of the rotor supports.
Gently spin the rotor to start it going. If it doesn’t spin, the polarity might be backwards – replace the battery in a different direction. If it still doesn’t spin, make sure power is flowing through the rotor supports (use the multimeter to check). Make sure that the enamel that is scraped off of the coil is perpendicular to the hole in the coil – that is, the coil hole should not be facing up when you see the bare ends of the rotor arm. Also, half of the rotor arm needs to still be insulated. If you scraped insulation off of the complete circumference of the arm, it will not work.
Milford parts painted blue. Worked through the first few steps of the construction process and found a few parts missing for the Z-axis. A blessing in disguise, it allows me to enjoy the construction process a bit longer.
The drive pulley was tight on the motor shaft. Before forcing it onto the shaft, which experience tells me is a really bad idea, I used a bit of sanding cloth on the motor shaft until the pulley slipped onto the shaft smoothly. Nice.
Ms. Postmistress came by with a long awaited bundle of joy!
Milford is a Shapeoko – a CNC mill created by Edward Ford (get it, Mill-Ford?) which I came across on Kickstarter. The images on Kickstarter are the prototype – in person, it uses metal and Makerslide extrusion. This is the dedicated website.
Oh cruel fate. To deliver my new toy in the midst of a release crunch. Oh well, I do need some time to clear my head from debugging software. Working with my hands will give me much needed relief.
Milford will complement Bottie-bot and Lil’Brudda, the two plastic squirters. I expect to use him to create printed circuit boards, and learn a bit about subtractive making.
The metal support pieces look a bit raw. Some sanding to remove the oxidation and then painting them should do the trick. It will also delay my ability to construct Milford, which will prevent me from stealing away from debugging to do assembly, installation and learning grbl and how to create PC boards by milling.
My derivative got featured on Thingiverse. I’m not sure why – I posted a derivative of a cool plastic toy that I vaguely remember from a time long ago. I modified the openscad code to make a grid of – 4×4 – so that I could print a whole bunch at once.
It’s there – right after the Sea Shell and above the Oh Crap! Toilet Paper holder.
