A couple of weeks ago I have finished building the latest version of my CNC machine. In size, this new CNC machine is a few cm bigger than the typical small square IKEA tables. The purpose of building it, was to have a test-bed for improvements, but also to have a CNC at home for making parts for my future projects.
Some of the improvements I have in mind are the integration of more tools for my CNC machines, like laser engraver, tangential knife, etc. Currently the supported tools are Kress spindles and also those typical Chinese…DC powered…air cooled…shitty spindles for milling, as well as Mk8 extruders for 3D printing.
Another thing that needed testing was some new features and improvements I was planing for the firmware of the controller and the controller itself. One of them was to improve the communications between the PC and the controller, by implementing a command queue on the controller. This allows the CNC machine to execute g-code commands one right after the other. In previous versions of the firmware the controller was executing a command and then it was waiting for a few milliseconds for the next command to arrive.
So after implementing this command queue, I had the opportunity to also do another sub-project I had in mind for quite some time, which was to make the CNC play music. I wrote a small python script, that translates note-duration pairs into feed-rate and distance pairs and generating a g-code file that when executed makes the CNC sound like a playing music. I uploaded a small video of a little demonstration on YouTube, which you can see bellow.
During the last 12 months I have designed and built a big CNC milling machine and 3D printer for a customer. The maximum work area of the machine is a bit more than 1m by 1m in X and Y axis and up to 30cm in Z-axis. The Z-axis carriage can accept either a spindle for milling or an extruder for 3D printing.
It was a good opportunity to consolidate things that I learned by building my small crude CNC machines and to go a step further. Currently I am designing another version with similar design, but with smaller dimensions (roughly about 40x40x20 cm travel in X-Y-Z axis respectively). So about 60% smaller than that big one. Also planed projects are improvements in my USB CNC controller and it’s software, as well as some more tools to complement the spindle and the extruder.
Bellow you can find some pictures of during the construction and the finished product, as well as a video with the device cutting some letters on corian.
A couple of days ago, I needed to cut 2 pieces of 8mm OD steel shaft, in order to make the Z-axis guides for my CNC Mk3.
I could probably cut them using the hacksaw or even by using just the dremel with a disk cutter. I indeed used the dremel with a disk cutter, but in conjunction with that, I decided to put the steel rod on my cordless drill and spin it while cutting it. Just for the fun of it and to make the cuts as straight as possible.
One of the upgrades I am making to my CNC is the change of the linear guide system, from a edge track with V-groove bearings like the one shown in Picture1, to a 8mm steel rod with LM8UU linear bearing.
The 8mm steel rods serve as the track for the LM8UU linear bearings and need to be secured to the CNC usually from their two ends. Given that the 8mm rods are have a round “profile” it is not easy (or nice) to just drill them and secure them with a screw. Instead they need some kind of a holder Like the one in Picture2, which is screwed on the frame and then the the 8mm rod is attached to them. You can buy one of these from ebay for a couple of EUR, but that has two disadvantages, first that you will have to wait several days for them to get delivered and second and most important…you loose all the fun of making them yourself. Although it is not too much fun if you don’t have the right tools (like a descent standing drill for example).
So anyway, I decided to design and build my own holders, despite the lack of any standing drill in my toolset. The initial design is shown in Picture3. In the design you can see a large 8mm hole, where the steel rod is inserted. There is a cut parallel to the 8mm hole, which allows the hole to be tightened using a screw, in order to tightly secure the steel rod. On the left side of the image you can see where that screw is fitted. The bottom half of that hole is threaded (M3 size thread). The other two holes on the right of the picture 3 are for fastening the holder on the frame.
I made the first 4 holders, which are for the 2 steel rods used for the Y-axis, but later on I decided that I could make the part a bit shorter and get rid of the one of the two holes used for fastening it on the frame.
I start making the part by cutting a 25mm long piece of 15x15mm solid aluminum profile. I use a small saw for metal to do this. Then the centers of the holes are marked with a caliper and pencil and finally with a punching tool.
I then use my improvised jig that uses a dremel and a dremel router base, in order to be able to make the holes as perpendicular as possible to the part. Unfortunately the dremel router base is not as precise as I wanted, but the result is acceptable I believe. One of the two handles of the dremel router base is a screw, which allows you to lock it to a certain depth. I noticed that it improves things a bit if you make this as tight as possible (just to the point that you can barely can plunge it down).
The holes are initially drilled to 2.5mm. After that the holes are widened to 3mm, except the hole that is used for the screw that squeeze the “jaws” of the part, which is only drilled halfway to 3mm. This is done because the other half will be taped for the M3 threads. The 3mm is the maximum I can do with my dremel. So the jig is useless from that point on and I just use a simple hand drill, to widen the big hole for the 8mm rod from 3mm to 4mm, then 5mm, then 6mm, then 7.5mm and finally to 8mm. Luckily the initial 3mm hole is a good guide and the hole remains perpendicular (at least perpendicular enough).
Next I use again the hand saw to cut the slot parallel to the 8mm hole and finally I make the M3 threads for the tightening screw.
After a final sanding and filing the holder is ready!
This is the first holder I made, using the old design with the 2 holes for fastening to the frame.