I while back I heard about RepRap and instantly fell in love with the idea of making a 3D printer. I began to think of ideas and acquire parts, including electronics. However, I was side-tracked for a while by life and only recently started putting real work back into the project. I do love the idea that a RepRap can make many of its own parts, but I want a bit more functionality in my own printer. I was originally inspired by the HydraMMM, a 3D printer and CNC mill.
Surfing around various maker sites I came across the Kickstarter project for MakerSlide. I thought this stuff would be great for my multi-purpose 3D printer so I became a backer of the project. I also found some more inspiration from this CNC router prototype made of MakerSlide (pictured here). Here’s what I have so far on my design:
This design differs from the CNC router in a few ways:
- It’s not nearly as done.
- The Z-Axis has the MakerSlide extrusion moving up and down instead of having a carriage ride on a stationary slide.
The Buildlog router uses larger carriages with motors that direct drive lead screws. I like how clean the design looks, but I have a few concerns. The screws look like normal threaded rod. It’s great because it’s super cheap, but will it be smooth enough? Also, typical threaded rod only has 1 “start” which means that the drive ratio is very slow. Compare that to the direct belt drive of Buildlog’s ORD Bot 3D printer frame. Like most belt driven 3D printers, ORD bot can move very fast in the X and Y directions. The Z axis does have threaded rods, but you rarely need fast traverse in that direction. Looking around I don’t see much of any 3D printers using screw drives for X and Y or using a stationary build platform. (Most move the Y axis.)
But I want my machine to be a lightweight mill too, and I don’t want to be moving around a large platform with wood or aluminum on it. Rather than searching all over the web for the answer to my lead screw drive question I decided to just test a few concepts. But to do that I would need a way to get my stepper motors moving so I need to assemble my RAMPS electronics from Ultimachine.com. This is about the time I realized that buying electronics before you are going to use them is a bad idea. My RAMPS V1.2 had been sitting around so long they had come out with two new versions with handy features that could come in useful in the future. Oh well, this will still work.
Some tips I came across when I would building my RAMPS kit: I have a wooden desk as my electronics work area, and my Panavise clone with suction base does not stick to it well. So, I bought a cheap plastic clipboard that I can attach the vise to. The clipboard has many handy features. It holds the suction for quite a long time (most of a day). It is clear, so I can see if I have things trapped under it. And it has a handy clip, which may come in useful to hold wires out of my way at times.
After I struggled to use my vise and my helping-hands tool to solder the pin headers on one of my Pololu stepper drivers, I found another nice use for this vise and clipboard. I put the stepper driver on its pin headers in a small breadboard to try to solder it, but the breadboard kept sliding away from my iron. Until, on my messy desktop, it hit the edge of the clipboard. Now I could do an entire header easily from the right side while everything stayed in place.
My RAMPS was now assembled, but I needed something to power it. I read up on converting a PC power supply into a lab power supply that could be used for many things, not the least of which would be my 3D printer. I looked at this site to get an overview of the process. The basis of my project is an old PSU I pulled out of a computer that mysteriously stopped working. I checked the supply the best I could by connecting resistors and measuring voltages with a multimeter. The PSU seemed to check out fine, so I had at it.
I started off by grouping the +5V, +12V, and Ground leads to some ring terminals. These ones were all part of the chain of connectors that run to accessories like optical drives (not the main ATX connector).
I had read many sites about the topic in the past and heard something about paying attention to the different “rails” inside a PSU and how it is not always a good idea to connect ones even if they are the same voltage. From this site I got some more info. I decided I would connect all my grounds because I don’t care a whole lot about electrical noise at this point, but that I would not connect the two separate clusters of +12V wires. Before I delt with the rest of the wires I started in on the 10 Ohm power resistor that is needed to provide a load so that the PSU will stay on. It’s connected between the +5V line and ground. I first thought of heat shrinking over the edges of the resistor, but I realized that this will stop heat-transfer to the case when I mount it, and later cut the tube off. This resistor got zip tied to the vented side of the PSU case.
I started working on my on-off switch for the power supply. I’m not sure why having a switch that controls the PSU like a computer does is better than just using the rocker at the back of the PSU, but I saw other people do it, so I did it too. Plus, this gives me the chance to add a fancy LED to the grey “Power OK” wire.
I drilled three holes: 2 for the switch and its alignment tab, and one for the LED. I held the LED in place with a bit of hot glue.
Next it was time to deal with those other wires from the main ATX connector. I just grouped all of the same colors together and crimped them into ring terminals. I read that one of the orange wires might be a 3.3V sense wire that needs to be connected to 3.3V. I just grouped them all anyway. Note that I am using odd-sized terminals. They are 10-12 gauge wire terminals, but their rings have an OD of only about 0.3″, as opposed to the more common 3/8″ OD for that gauge. I found these at an auto parts store (I think) and they’re nice because they can hold a good grouping of wires and still bolt nicely to the binding posts.
Here you can see the additional ground wires from the ATX connector and the +5V, +12V, and ground from the accessory connectors attached to the binding posts. Also note how one of the ground wire groups has the larger style ring terminal and it is sandwiched between two of the smaller ones.
I put the case back together now, moving the fan outside on top to give more room for the extra wires inside.
What about all the other colors? Some sites say to just cut them off short. Other sites break out all the voltages to different binding posts. I decided to just leave them hanging out of the original opening but shrink wrap the ends so they don’t short on anything. I may find that I’ll need these for something later. I also left the fan speed control wire sticking out with these. I may find that I need to tell the fans to turn faster if the PSU doesn’t have its own temperature regulator.
Time to fire this thing up and test. The fans are spinning! And the LED is on! I checked the voltages and got 5.0249V and 12.540V with my multimeter. So far so good. Next I’ll start getting my stepper motors wired up to RAMPS and get some things moving.
I noticed I forgot the fan guard so I attached that carefully with connectors made just for the purpose. You’ll also notice that the screws I’m using to hold the PSU case together aren’t the original ones. Why? Well, I couldn’t find them, but I did find these cooler looking ones that I had salvaged from the frame my cousin’s dead Alienware PC case. I think they go with the things-sticking-out-everywhere theme of my PSU.
