This is a project I start to gain skills on design and metalworking. Usually I only do simple pieces.
1. The idea: A precision mini-drill aimed to drill pcb boards (only the drill, not stand). It will hold typical carbide drills with a mini collet and rotate to about 10.000 rpm. Future work will include doing a stand for manual drilling and, why not, using in an always wished cnc machine.
2. The draft: I start about two weeks ago doing some drawing in acad. Below is the current state.
I’m sure this is not the best design, with lot questionable things. But I’m also sure it would be a lot better than the cheap drill I actually use for pcb drilling (and even the dremel).
3. The first piece: And this is the first finished (almost) piece I do some days ago. It’s done on 2024 aluminium and looks pretty cool.
- Diameter vary from to from 23.990 (front) to 23.983 (back). Maybe there’s a very slight misalignment of the spindle, fixable doing a simple adjust.
- In the rear I measure 15.995 and the bearing fits without pressure, so interference fit was not achieved, but it’s ok.
- Int the front, the bearing doesn’t fits easily; the measure I get from the hole is 15.975, so it’s a bit more tight than the target interference but I think that heating the piece will do the job. Thermal Expansion Coefficient Al 2024-T3 = 22.68 um/m C -> the hole will expand 18. 144 um raising temperature by 50 ºC.
I didn’t measure all sizes; only the critics ones.
4. The next: The next piece I want to do is the one in the center; but currently I don’t have the required tools (boring tools for deep hole), and after struggle myself if make or not the tools, I decided go the easy way and do an ebuy. May be meanwhile I try the main axis.
The more I detail the draft, the more find myself saying “how the hell will I do this piece?”. But that’s the idea.
Up to this time I have read several books on metalworking, but now I realize how different is theory and practice.