[PhoenixMetal]

I'm new to machining and was wondering if it is possible to make something like this with a milling machine.

Basically its a rectangular inner cutout with SHARP 90 degree corners. Can this be done or does it require an EDM machine to do this sort of thing?



Thanks!

[acondit]

Sure, just use a 0" diameter endmill. Seriously you could use your mill to broach the corners or as you suggested use EDM.

Alan

[scudzuki]

That's wire or sinker EDM territory there.
Joe

[MrWild]

Mill out the pocket and file the corners to shape.

[PhoenixMetal]

Thanks guys - well you answered my question. Its a job for EDM.

Thanks!

[rwskinner]

Why couldn't he use a slotting tool?

[irving2008]

Becasue any rotating tool will leave a radii in the corner no matter how small it is...

[Khalid]

Okay... mill and use scrollsaw...

[acidcustom]

what about just running a cutter down the corners with the centre of the cutter being on the right angle of corner this will able an insert with right angles to go right to the edges

[derekj308]

Actually there is a cutter that can make this shape. I think it was inverted by a German guy. I'll try to find a reference to it on the web and post the link.

Cheers

Derek

[derekj308]

This is something but not exactly what I was looking for. A little outdated perhaps but shows it ain't new.

http://query.nytimes.com/mem/archive...629C946896D6CF

[irving2008]

what about just running a cutter down the corners with the centre of the cutter being on the right angle of corner this will able an insert with right angles to go right to the edges

that might work, depends on the customer's intent, but doesn't meet the specification as stated - which was SHARP corners.

[derekj308]

Nearly. I'm sure there is a commercial tool available, I just can't find it on the web.

http://demonstrations.wolfram.com/Sq...reeDimensions/

Use the "Cutting Tool View".

[derekj308]

Sorry guys I got carried away. It may not be as practical as EDM but it can be done by driving with a rotating tool.

[jemmyell]

what about just running a cutter down the corners with the centre of the cutter being on the right angle of corner this will able an insert with right angles to go right to the edges

DragonCNC can generate these corner overcuts automatically. This feature was added for inlaying shapes with sharp corners.

-James Leonard

[PhoenixMetal]

The intent of making a shape like that would be to make the female portion of a die, so inserts in the corners wouldn't be ideal.

I'm curious, what is the smallest radius cutter that I could practically use to get a really tight radius?

[JamesP]

EDM may be the right approach to tackle such problem.
My 2 cents

[DareBee]

Depends what you deem as practical.
You can be endmells that are .001 dia.
A long reach .03 will reach .27
I would consider a 3/32 to be the smallest "practical"
Carbide of course.

[Geof]

....I'm curious, what is the smallest radius cutter that I could practically use to get a really tight radius?

There is another question you should ask: Is a completely sharp corner desirable, perhaps a small radius will result in longer die life?

If you have a really sharp corner in the female die you need a correspondingly sharp corner on the male die. This sharp corner will be far more susceptible to wear and damage than a radiused corner.

It has been my experience that often designers call for things such as sharp corners simply because they are too lazy to fully consider all aspects of the product. Nearly always a radius is tolerable and sometimes it is preferable.

[Stepper Monkey]

Geof is right, just because a sharp corner was specified doesn't mean it is optimal or necessary. Often it is laziness in the design that the customer will overcome quickly when it affects the production cost so dramatically. Just ask.
I am betting that a small radius may be important to prevent cracking as well, sharp corners are just inducing stress risers into the design. If clearance for accepting a perfectly square item is necessary, then relieve the corners a bit in just the way acidcustom suggested. Cheap, strong, and performs the function.

You are putting the cart before the horse trying to figure out how to make this shape if you haven't determined from the customer what the materials, design parameters, and end use of the part are. It may not be necessary to make it the way they spec'ed it out, it usually isn't.
A bit of feedback from you often saves the customer a lot of money while making your job easier, and gaining loyal customers. Anymore it seems that you need to be a consultant as much as a machinist to really serve a client, as very few customers staff competent practical engineers so you just can't blindly assume they knew what they were doing when they drew up the plans. Its too often customers unnecessarily spec nigh unmachinable items, and too often that shops just unquestioningly try to follow that spec to the detriment of all involved. Don't be afraid to ask.