what type of file?

[landtank]

I've designed some plates and need to get them cut out. They are pretty irregular, so I'm thinking they need to be lasered out. What type of file do you need to provide for that type of work. Right now I have it in .dwg and .dxf. I'm thinking .dxf is ok but before I start to call around I'd like to know what I'm taking about.

Thanks

[davegonz]

LandTank,

Most shops I have dealt with...when I was working...could work with native dwg files as well as dxf. If your plates are going to be cnc cut, then they really like it if you can give them .SAT and/or .STEP files. That way they can import them straight into their CNC software (mastercam..etc). Let me know if you need help converting those to solids. I can model them up in Solidworks and export it out to SAT and or STEP.

[esh]

The laser cutting service I used for my bullbar pieces sounded like they could (and had) work with many different files. His first choice was .dxf

[scottm]

I'm a project manager/project engineer at a machine building shop, I get a lot of files from outside for our machines to cut. 3D dies, nests, and stuff get interpreted and massaged by a couple other guys, 2D I make into .dxf files. The mills in my shop can use .dxf, I usually send out lasercut in .dxf, the oldest version .dxf I can save/export in. I always make sure I explode everything, verify to scale, and get rid of hidden lines, centers, dimensions. Notes are OK, text doesn't seem to bother them. The machinist always gets another file or print with dimensions, they save my butt regularly when something isn't right in the file.

[groucho]

just out of curiosity, are they being machined out of a block of metal on a milling machine, or are they being laser cut out of flat stock and then bent using a press brake? our programmers use unfolding software that comes in a .igs format. This is then taken and programmed for a flat, then sent to the laser to cut, and then bent on the brake.
in any case, both should be able to be imported. we do it all the time for prototype work.

[scottm]

I'm unfolding a customer's drawings to send them to laser-cut this morning. There are a lot of multi-segment straight lines I have to delete and make into one segment. Sharp corners get 1/16" radius so I don't have to deburr after laser. Tapped holes near bends are deleted, we'll have to drill & tap after bend, otherwise they'll distort too much when bending. Slots are great, expensive to mill but cheap for laser. I'm adding .030" for each bend on 12Ga, thinner stuff I just go from the inside of each bend. We don't get a lot of call for thick, bent pieces, usually we weld thick stuff. Anyone have wisdom on what to add for various thicknesses of bent sheet? This customer specified all 7Ga, but told me to go with whatever would work easiest. These are brackets holding PCs on stationary machines, 12Ga will save us trouble and him money.

[scottm]

If you're going to tap a hole, make sure you draw it to the tap drill size. I just noticed all the #12-24 tapped holes on these are bigger than clearance, have to change that. I'll also contact the engineer and ask what he's thinking, we don't have any #12-24 taps, or screws. Our older machinists usually have oddball taps and such in their toolboxes, but they're scratching their heads on this one. Few of us have ever seen a #12 tap or screw. Darn engineers, they need to build something once in a while.

[groucho]

Originally Posted by scottm

Anyone have wisdom on what to add for various thicknesses of bent sheet? This customer specified all 7Ga, but told me to go with whatever would work easiest. These are brackets holding PCs on stationary machines, 12Ga will save us trouble and him money.

What are you building? What's the material? Are you air bending or are you coining? What bend radius will be used? If you're not familiar with bend deductions/allowances my suggestion would be to do what we do to obtain the best info: experiment with scrap material.

[scottm]

Bending on a manual brake, our big bender will wait 'till they finish building our new shop in a few months. Sheet metal usually isn't as critical as machined parts, these aren't too critical, but I like to get as close as possible. This is how I experiment, trying to get it more accurate than I really need to. We'd weld and mill if it were critical. Hey, I just found it in my Machinery's Handbook! I'm such a lazy bastidge, why didn't I look here before? Add 1/3 to 1/2 the thickness for each bend. That's roughly what I'm already doing, based on comments from the sheet metal guy.

[groucho]

Our tolerances are +/- 0.005" 99% of the time. Our biz is precision sheet metal stamping, laser cutting and forming for the high tech computer and medical industries.

Glad you opened that thick book and figured it out. Best friend for us.