Need Advice About Side/Slot Milling in Steel

[ChandlerJPerry]

Plus 1 on the roughing end mill. I've cut through 1/4" mild steel with a 1/4" HSS roughing end mill in a small mill (g0704) in one pass and had no problems, cut through like butter.

That's great to hear. I don't own any roughers so it sounds like it would be worth getting a couple different sizes and experimenting. There's no reason the slotting operation has to be 1/2", it's just what I had on hand. The less swarf I have to clean up, the better!

 

[homebrewed]

Do the "window" has to have round edges at the bottom?

Whenever you're cutting a feature in a hollow material, the answer is usually some sort of saw, not a mill. An acetylene torch or plasma cutter with a guide would be far quicker. And then you can just clean it up with the mill. With the bonus that you keep the chunk you cut off for some other use, instead of a mountain of swarf.

It takes more than one of those little portable air compressors to run a plasma torch. At least, based on my own product searches. If the OP doesn't, that might be either a deal-breaker or an excuse to get one. If it's going to save him money or time (same thing really) in the long run then it's an easier decision.

 

[ChandlerJPerry]

It takes more than one of those little portable air compressors to run a plasma torch. At least, based on my own product searches. If the OP doesn't, that might be either a deal-breaker or an excuse to get one. If it's going to save him money or time (same thing really) in the long run then it's an easier decision.

I do have a 30 gallon compressor. Not sure what the air demands are like for plasma, I've used them before at some previous employment but those were hooked up to effectively bottomless industrial air compressors.

 

[homebrewed]

I do have a 30 gallon compressor. Not sure what the air demands are like for plasma, I've used them before at some previous employment but those were hooked up to effectively bottomless industrial air compressors.

IIRC they start around 4CFM. But the requirement may vary depending on the thickness of the material you're cutting. Before buying one I would read through the product manual for more specific information.

 

[WobblyHand]

IIRC they start around 4CFM. But the requirement may vary depending on the thickness of the material you're cutting. Before buying one I would read through the product manual for more specific information.

You need dry air for plasma cutters.

 

[jwmelvin]

The bigger issue with a plasma cutter for this application, to me, is the hardened edge it leaves. That would be hell to clean up with a mill. Angle grinder seems better, as suggested above. Or just mill the perimeter.

 

[ChandlerJPerry]

The bigger issue with a plasma cutter for this application, to me, is the hardened edge it leaves. That would be hell to clean up with a mill. Angle grinder seems better, as suggested above. Or just mill the perimeter.

To clarify, I am just milling the perimeter in order to knock out the window. However I would still like to accomplish that task in one pass as opposed to two.

My main concern with an angle grinder is accuracy and the fact that I'll be making a cleanup pass anyway. 1/4 inch steel isn't something that's super quick to get through with a cut off wheel in my experience so I'm honestly curious about if it would save me time/effort vs just doing the whole thing on the mill anyway with a good roughing mill.

The clear best answer would be waterjet/laser but those things don't really apply in the hobbyist world.

 

[WobblyHand]

Question for folks, does sendcutsend do things like this, or only flat stuff?

 

[MrWhoopee]

Get yourself some of these. I use a lot of 8mm finishers because they will fit in a 5/16 collet, but metric R8 collets are cheap too.

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www.aliexpress.us

 

[ChandlerJPerry]

Get yourself some of these. I use a lot of 8mm finishers because they will fit in a 5/16 collet, but metric R8 collets are cheap too.

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www.aliexpress.us

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I'll be honest, I've always been kind of gunshy about the AliExpress cutters/tooling. Granted I have been spoiled by working in professional machine shops with no shortage of OSG, Niagara, Harvey etc. Of course I doubt they're that good. But do you at least get your $7 worth out of them? The electric blue coating definitely raises my eyebrows .