It’s tough. And it’s tough to get the supports to cleanly detach without a big zit. Sanding ruins the clear look. But for structural parts it’s strong…
3 Likes
OK, so today (in theory) one of the mechanical engineering students and I are meeting in the engineering maker-space (I don’t get to go myself since I am not engineering), and he is going to machine out my cams out of 0.375" 7075-T651 Aerospace grace aluminum. I think he’s going to do it on one of the big bridgeports (I bought a 12x12 slab). It’s funny the student was like “you should buy 6061 as it is so much cheaper”. Well yes, it is but considering the 7075 was only $30 for enough material to make 12 cams (enough for 3 tables) it seemed pointless to get a less stiff material when I am going to all this effort due to a lack of stiffness. Apparently they have an anodizing shop that does it cheap for the students. (and of course I will hit those in the Glowforge once anodized). I had planned to tap the holes, but was concerned about adding that complicated step to the machining process (if it was a commercial shop I wouldn’t have worried, but he’s a student). Once I get it all finished I will then put out an instructables (and hopefully a project-kit on Servocity, which makes the entire BOM of all the mechanical bits a single click purchase)
5 Likes
We made chips today! Got the stock all, squared with that beast and ready to mill in the morning with flood coolant full blast…
6 Likes
That just LOOKS scary! 
1 Like
I’ll post the movie, that surface was like butter…
3 Likes
Forwarding this to our ME team, they’re gonna love it. Epic work Henry!
2 Likes
Well epic in the sense of saga I guess. The fun thing when you make an error on the GF you might cut a bit more acrylic than you expected (or your guacamole tastes like crap) but when you make a dumb choice (got creative - sigh) with 7075-T651 it is more spectacular…
We had the somewhat naive plan to release the part not the traditional way of either soft-jaws or tabs, but instead would simply face mill down with the 2.5" fly cutter to the pocket level. Uh, yeah, here is the reason that the pros don’t do that… Well I’ve already modeled the soft-jaws (and continuing our streak of ideas, I am going to try 3D printed soft jaws using Formlabs Tough resin jaws). I think if this was my milling machine I would machine out the jaws, but getting access to this is somewhat clunky so saving the time might be good (I don’t care that we are burning stock, it’s pretty cheap as it turns out)
The front side is glass smooth, although you see tool marks they are not notable with your fingers
The piece bouncing into the cutting heads did not help the surface finish. As it turns out the piece was a write-off anyway, as I had accidentally made a CAD error (after making the parts on the GF which I had used to debug) so it had to be redone.
4 Likes
I’m honestly more amused by the people casually ignoring the screaming machine throwing bits of metal everywhere…it’s amazing what one gets used to!
4 Likes
Well, because the guy behind them had just really crashed his CNC into the stock with a horrible grinding crash. Our stuff was much more benign, also we had the professor helping us, so they sort of figured we had a clue._
2 Likes