Hi all,
First post!
I've been working on a desktop CNC design for about a month or two now. I'm mostly doing this for fun and to learn a little more about machine design and construction. I'm hoping to be able to mill metal on this machine though it's not completely clear to me (yet) what sort of stiffness you need to achieve for that - a lot depends obviously on what sort of cuts you are taking. I'm starting to get a better feel for working with metal which I've really never done before, also did quite a lot of reading on this.
I've gotten a lot of information from these forums so hopefuly someone will find my stuff useful...
It's a combination of scrap I've had lying around, scrap from work, cheap ebay stuff. Trying to keep the costs down as much as I can. The working envelope is going to be about 100mm x 200mm x 250mm or so. Initially I was aiming larger but it gradually became smaller and smaller
The design looks something like this (not all details were drawn):
It's based around aluminum extrusions reinforced with aluminum plates.
Here's a piece of this that I'm building:
It so happened that the narrow surface of this 60x90 extrusion is quite flat allowing for the rails to be mounted directly onto the extrusion. I've made some compromises based on the stuff I could get, e.g. these rails are a different type and I've joined two shorter rails together to match the second rail I had. I hope I won't regret this some day later, travel across the joint seems reasonable, it is mostly the seals that are a bit sticky... As the rails were a different type I had 2mm to bridge between the mounting surface of one set of blocks to the other.
The Z axis is a Festo pneumatic linear actuator I got for cheap on e-bay that I've (somewhat crudely) converted into a screw driven stage. This is another example of a compromise as it looks marginal in terms of stiffness, we'll see I guess... Once I have a CNC machine I can build something better The stepper driving this is a bit on the small size but my calculations seem to indicate it should be OK. It was just a good fit and an easy mount to the actuator.
I got a variable speed router on sale that looks reasonably good:
And I'm waiting for a router mount that I ordered from K2CNC that should fit this router... (3.5")
I'll need to figure out how to align everything once it all gets put together. There are also a few other loose ends to tie up in the design.
Anyways, that's about it, what do you think? If anyone is interested in more details I'll be happy to provide...
Guy