Milled Out A Hovertank

[John Bear Ross]

Hello, all.

Just wanted to show off my little bit of effort over the weekend.

http://www.johnbearross.com/prototyper.html

Roughing didn't take too long. The finish pass with a 1/32 x 3/16 x 3/32 ball end mill took 34 hours, but I think I was using the wrong strategy. Also, a long-reach ball end from bitsbits is on the future purchase list.

Thanks to Nick Carter for getting me addicted to this new venture.

Best,
John Bear Ross
www.johnbearross.com

[SpeedsCustom]

Nice work My friend, nice too see another Taig user making good stuff. Though, 34 hours does seem like a long time, what was your stepover?


-Jason

[John Bear Ross]

Originally Posted by SpeedsCustom Nice work My friend, nice too see another Taig user making good stuff. Though, 34 hours does seem like a long time, what was your stepover? -Jason

I was working at d/9 or .0034" stepover.
5 IPM, because I'm having seizing issues in the X axis at higher speeds.
Milling strategy was a X, then Y, grid pattern. That's probably why it took so long. I'll try a waterline strategy next time, or the grid pattern with a longer tool (longer length of cut).

Best,
John Bear Ross

[BobWarfield]

That's fun!

I used to do military miniatures long ago in a galaxy far away. I can imagine a small CNC is one of the ultimate modeling tools.

Best,

BW

[BrendaEM]

Are you going to make lots of metal ones, from that master, such as rubber molded rotational castings?

[Stepper Monkey]

After the roughing is done, I often use profile bits and not mills on wax for the finish pass. They speed things up a lot, and they are also available from bitsbits.com.

5 ipm is a hair less than a third of the speed I usually do wax cutting at on a Taig. If you are getting axis seizing while moving that slowly there is definitely something wrong - either with the gibs or similar adjustments, or perhaps your motor/driver matching at those speeds (it might be quieter and smoother at faster speed ranges, or you may even need a different motor setup). In any case, try to aim eventually for 10-15 ipm for wax (I use 400mm/min = 15.7 ipm as a beginning baseline, but then again I've been doing this awhile, too). There is definitely a learning curve to the cut strategies to get it up there and even well beyond, but it isn't too difficult to suss out. After you get the X and Y to the speeds you want, your cut speed will be limited by the ability for Z to reciprocate as fast as you need with that many small elevation changes (i.e. cut speed will be will be limited entirely by the Z acceleration setting). For that the only cure is a lighter Z, therefore a lighter motor, and there are some very light and powerful motors that can replace the monstrously heavy original. You can even just use a simple Nema 23 servo and get better speeds and very nearly the same wattage of cutting power for under a couple of pounds weight.

That is some awesome work. Keep it up. I'm glad to see someone is still playing Battletech!

[John Bear Ross]

Originally Posted by BrendaEM Are you going to make lots of metal ones, from that master, such as rubber molded rotational castings?

That is the intended end, though not with this particular master. This little guy will probably get melted down, and become a new test piece, though not before I show him to the wife, to justify my expenditures

StepperMonkey, thanks for the info. I'll check my gibs and see what I get.

Best,
John Bear Ross

[under-dog]

Cool.

I have a sherman in the works myself.......