I wasn’t able to adapt the x-y stage to my drill press, so I spent the weekend making a support system and adding a z-axis. There was horrible vibration from the dremel, which I eventually traced down to the chuck. I alleviated the vibration by replacing the chuck with a collet.
Some parts of the revised CNC would benefit from a little more accuracy and precision than my current set of tools can manage. It may be possible to make a crude hand-operated mill out of my drill press. I purchased two steel plates from Lowes and two drill-press clamps from Home Depot, which I will slap together tomorrow morning. Total cost was around $40.
The idea is to create a stencil, trace the image on the material, and use the improvised mill to cut it out.
I will purchase some thin aluminum flashing to use for making stencils of the parts I will cut out of HDPE. This way, if I mess up while machining a piece (or need multiple copies), I do not have to painstakingly measure and redraw the cutting marks each time. Not sure why I wasn’t doing this before, but it seems like a no-brainer.
I spent more time building the mini CNC than updating the site. After completing the mini CNC, I discovered many shortcomings. Sleeve bearings are simply not a good choice for this kind of machine. Too close a fit, it tends to bind on any debris that is picked up; too loose and the assembly is no longer rigid. The play compounded horribly on the x-z axis, which deviated 1 to 2 mm under load. Therefore, I will use roller bearings that ride on rails instead. Polycarbonate is also a little too flexible and expensive, so I am going with 3/4″ HDPE sheets. The threaded drive rods had a lot of friction and are slightly warped right out of the store. I may cave in and buy some Acme lead screws. Lastly, to maximize the amount of workable area, I am going to go with a moving gantry design instead of a moving bed.
My first task is to think about how to making the linear bearings- stay tuned!
Removed stepper motors because slight misalignments caused the assembly to jam. It may be necessary to include a flexure shaft coupler between the drive shaft and the lead screw. Finished all 3 translating stages and reinforced the chassis.
