Cutting SS or Ti Possible?

[bprzybyl]

Hello,
What an awesome website! This has definately fed my thirst for knowledge on CNC design except for one thing.

Why is it that it's only possible to cut soft aluminum? My main purpose for a CNC machine would be to cut .015"-.03" sheets of Stainless Steel or good grade titanium. What would need to be done in order to build a machine capable of performing this task? I wanted to cut large sheets at a time, so I was figuring on designing a gantry style one, very similar to the one pictured here

http://www.kellyware.com/images/Kcnc_2_sm.jpg

with the dual lead screws (probably roller screws, something I saw on here) for the X and then the Y and Z be held up above, allowing cutting of a 24"x24" sheet at a time.

If it is not possible to do this through the machine style above, what needs to be changed in order to achieve my goal? Are there any websites which give more information on mainly metal cutting machines? I've mostly found ones that focus on wood, even more so ones focused on engraving.

Thanks,
Brooks

[Carel]

Is it really necessary to build your own router? I assume that by cutting sheets you want 2-dimensional shapes. Laser-cutting, thus make a drawing and let them make it, is in my experience dirt cheap. Just a thought.

Carel

[bprzybyl]

I don't want it just for that. I would like to use it for other purposes, unforeseen at this point in time. I imagine any other uses would probably only need aluminum. But for this purpose, I need it to cut those materials.

[Carel]

Well for milling metal in the size you want (24*24), you need a lot of metal. Look at Stevie's Gantry Mill Project and that machine is smaller than what you want. So work on your "unforeseen" and see where your 2-D goes into 3-D and look into that size of mill. You don't want to shoot mice with a 6" cannon.

Carel

[bprzybyl]

That thing's HUGE!!!

What if I were to cut down the size I wanted to cut. The pieces I want to cut out for this project would require a minium 6"x1" and then the thickness of material in the z. Would that make cutting TI or SS more feasible?

Thank you for all of your help (quick responses!),
Brooks

[Carel]

Oh yes, now we're talking reasonable sizes. The next consideration will be: is it for main business, support of business or private project(s). And required quality and projected time of course. This will all be decision factors on what you need. And the thickness of your wallet. As your market and supply lines are completely different from ours I can't help you with brands, only with downtalk in size it seems.

Carel

[bprzybyl]

Business? HA!

This is just for my private projects. I am no more than a Mechanical Engineering student. That should also give you some insight to my budget . That doesn't mean I won't be allotting any money toward it. I figure I can pull off around $500 for the machine alone. This could be increased as required, but once it gets into the $1000, I think I've seen some for that much, but don't quote me on that.

Projected time? As in build time or machining time? If Build, then I would like to get this completed and running by the end of summer. If machining, as long as it take an hour to cut a ~12" line, at this point I really don't care. This is not being done to fulfill any deadlines or requirements, aside from my own.

As for quality, I figure it would need to be accurate to at least .004", which to me sounds like a horribly high tolerance, but I believe would be feasible for my current project. But If possible, I would like to get it as accurate as possible within my budget.

Is this still possible?

Thanks,
Brooks

[Carel]

Well, as with every problem, slice it. You need a PC with software and the ability to generate programs for the machine to run. Without an actual machine you can run this and get experience. For a mill you need 3 positioning drives, whether they are steppers or servo's, their drivers and the interface to the PC. This can be build and tested as a separate unit and you can drive it from the PC to emulate a mill. The mill itself can be bought as a ready to go CNC-mill, you don't need the drives then. Or you can buy a manual benchtop mill, new or used, on which you make the parts you actually need and the parts to (gradually) CNC it. With patience, looking over the horizon and wisely spend money it's doable. Good luck.

Carel

[RotarySMP]

Remember, stainless work hardens, you you can't just sit their annoying the hell out of it with a dremel spindle. You need enough power to cut the metal. Start with a chart the feeds and speeds required to cut SS, then work out what cutting tools you would need to make the parts you want to make (a 1mm mill will need different speed and power than a 6mm).

From there you will be able to work out the spindle RPM range and power required, and the axis speed and thrust.

[bprzybyl]

As for PC & Software, Those are on a separate budget. PC I can make from spare parts around the house.

Where does one find a cutting feeds & Speeds chart? I'll do some google-ing in the mean time, but any help would be great.

At this point, I think I've dropped the gantry design, and I'll be focusing on a mill design. Maybe I'll try to get a small manual mill, and then work towards converting it as you stated. Has anyone ever built a mill? Maybe I could just build that and then focus on CNC.

Thanks everyone,
Brooks

[Carel]

CNC is an expensive candy-shop. Some people have mega-buck machinery and produce lousy designed, low quality ehh... crap. Other people produce wonderfull things on next to nothing. Allow yourself to decide in a year, yes it is nice, but not my cup of tea, and it didn't cost a fortune. A milling machine is just a mean to realise your designs. If you want for example, make a steering head for a motorcycle, it is nice to have figured out in advance that if someone brakes, it won't break off or fall apart. It's all part off Mechanical Engineering .

Carel

[bprzybyl]

"Expensive Candy Store"

Haha. I like that. That's pretty much what it is too. Hopefully I can make a decent one which will output good work. It won't be a year worth of thinking, probably 5 more weeks or so. I can do a lot of machine work at school (Big Bridgeports and machine lathes, Grinders, drill presses...heaven). I pay enough to go there. I'll use stevie's build as well as the one at 5bears.com to help. I might build an all wood one to begin with, gantry style of course, using heftier steppers/servos and such, and then just use it all to convert to a full aluminum one.

Thanks,
Brooks