Started machining the 2nd prototype over the weekend. This time I decided to be less wasteful and try keep the core of the billet. It was an interesting exercise in creating toolpaths and fixtures to do so, but at the end of the day, the extra time was not worth the value of material saved ?
Billet was rough machined closer to size using multiple facing operations. Much easier to remove material this way than side cutting.
Part way through OP1, outer walls finished and a heap of 10mm holes drilled through the billet. Again, drilling is a much more effective way of removing material than milling at that depth. Though, a thru spindle coolant carbide drill would have been a much better tool for the job than the standard HSS drill I used.
OP1 all done
Bottom of the part after OP1
Next I machined a solid top panel. This is used to support what will become a square hollow section in the vises while machining and prevent it from being crushed. It also has holes to allow me to attach the core of the billet to it so it's secure when I cut through and free it from the outer section.
Top panel in place and fixed to the core of the billet.
Everything ready to go for OP2. As there is no reference to pick up on here, the first step was to machine to rough height and take material off around the perimeter to allow the probe to touch off on the side walls machined in OP1.
After OP2.
Finally, the almost finished part, and the core of the billet saved for a future project. About 4.5kg of usable aluminium left. Which is somewhere around $60NZD worth of material. There is a witness line from where I machined from either side, largely present in the middle and not at the corners. The Material must have moved due to internal stress once it was parted off from the core. No stress for a prototype though.
I forgot to save this photo to my phone when I uploaded it to my instagram story. Saves me writing a caption for it.
This is the internal corner that was finished with the end mill above. Not too bad considering the length to diameter of the tool. Will clean up nicely with bead blasting.
All in all the whole thing would have been a lot easier if I had extrusion available at this point. Or access to a wire EDM machine. But I make do with the tools I have. Something I find myself saying often, and laughing about when I say it. I started my business with a CNC router I built in the garage at home. Now, the machine alone is worth somewhere in the region of $150k NZD and I still call it making do ?
But if it makes people think of bacon as it has for you, surely that's a good thing?
But it was just a proof of concept anyway. And it has done that, much happier with the power button now.
