I’m overflowing with detailed questions for an experienced machinist to answer. Since I suspect that this group of Doper Cutters may be pretty small, instead of posting up my questions, i simply ask- anyone out there a working machinist?
Willing to give advice to someone well versed, but lacking skills to cut stuff myself. -whimper- I tend to break end mills LONG before they need re-sharpening. 
Chirp up if you’re a pro, or serious amateur- or email me?
Cartooniverse
You want Tuckerfan.
He’s a pro.
True enough- but from what I read of his life in a post just the other day, his Tucker tending days may have suddenly come to a halt. If possible, I’ll email him. Thanks !!
Anyone else?
Actually, the cops dropped all charges, & his ex-boss is unlikely to do more than mouth off.
I worked ten years in my dad’s shop. Anything I can’t answer for you, I can throw to him and see what he says.
My spousal unit was a machinist and a tool maker, lo many years ago. He may be an engineer now, but he’s still a chip maker at heart.
I believe you have our number…
I guess I qualify. I’ve been working in a machine shop since 1981. Most of my experience over the years has been on CNC lathes, but the last 5 years has been on CNC mills. The last couple of years has been as programmer on mills and lathes. I’ve also done my share of manual machining, mostly small lathes, but also on Bridgeports. Also have done a small amount of manual surface grinding. Our work is small lot size production work. The materials cover aluminum, steels, stainless steels, high temp alloys and titanium. Does any of this cover what you’re looking for?
Marry me.
Uh… I mean, yeah !! I’ll email all three of yas.
Dirtyhippy, it sounds like you may well get the gig, because yer gonna know alllllllll the answers.
It’s all 60601 al. work.
Coolness !
( Yeah, FCM, I got your number all right. It’s twenty-seven. )
Hey, don’t be shy about discussing it here. Some others may learn from the experience too.
I’m OK with that. Or an “Ask the machinist” thread, with my fellow chip-makers.
DH
I have a 6" Atlas in my kitchen, but I’m far from a machinist. I have added some upgrades to the tool holders and such so I can run carbide tri-cutters instead of the brazed on or ground tools. I’ve done some pretty neat projects, parts for a guy’s Harley and (one of) my dad’s 280Zs. The old machinist mentor I had at work retired then died, I’m glad I learned as much as I did off him while I had the chance.
Fair enough ! How hard is it to cut perfectly opposing radii in a plate of metal? There will be other cuts into the piece, but from what I hear, the radii are the Waterloo here.
I used to make chips. I did a lot of stuff on my uncle’s lathe. Created a mess a lot of the time, brutalized his tools. When my machinist retired last year, I paid my uncle back in spades for the damaged tools, by delivering tens of thousands of dollars in stock, cutters, and whatnot for milling machines, lathes and such.
Oddest thing I tried on a lathe? Cutting down Delrin to make something. When heated and cut, it released cyanic acid. Yep. Cyanide gas, right in the shop. Lovely. -gag- Uncle smelled it and came running to hit the large box fan built into the upper wall.
Live and learn.
How many radii? Four would be relatively simple. More than that would be problematic. Also, what sort of metal would the plate be, and how big and how deep would the radii be?
I gotta disagree. The easiest way to do it would be with a rotary table or an indexing head. However, even without either of those, it still isn’t all that hard. You just need a straightedge, scribe, protractor (or a set of triangles), Dykem, and a rag.
It sounds like a slot through the material in the shape of an arc. If that is the case, it is a relatively easy thing to do on a CNC. The computer on the machine just tells the tool where to move and how. Then it comes down to the size and depth of the slot. If it is 1/8" wide by 1" deep, that becomes an issue because you end up using a weak tool (think length to diameter). 1" wide by 1/8" deep is a lot easier, you can use a bigger and shorter tool (and stronger). For production runs, the CNC is the way to go.
Ah, arcs. I was thinking that it sounded like he wanted degree markings. If it’s arcs, then yeah CNC’s the way to go. Cutting it won’t be so bad if it’s aluminum. Stainless steel, however, would be a real bitch. (Used to have machine out ceramic in a 3/4 deep by 1/8 wide slot in stainless when I worked in the foundry. Royal PITA.)
Hi I’m back. Yes, it’s aluminum. Weight is an issue with stuff I make, and have made.
Sadly it IS 1" thick stock and the arc/slot will be either 1/4 inch or 5/16 inch.
This is not do-able? Or, we’ll break a lot of bits but it can be done?
I didn’t mean to say it was impossible, just that it would be harder. Right angles are a snap, you could do them with your eyes closed. More than that, and you’ve got to make additional setups or calculations. To me, more work = a problem. So it’d be problematical. 
But if he’s talking arcs, that’s a different matter. I did all my work on Bridgeports, never used a CNC, so I can’t help him there. As far as material goes, a 1/4" slot in inch thick aluminum shouldn’t be a problem. Probably do it without breaking an endmill, if he’s only making a few.
Cool. I like aluminum. We use it at work to prove out programs for tougher materials. 1/4" shouldn’t be too bad. A standard 1/4" end mill shows a length of cut at 1-1/8", which would certainly reach through 1". The through part helps, too. It is easier to flush the chips through. For a 1/4" slot, I would use a 7/32" (.2187") end mill. For a 5/16" slot, I would use the 1/4" end mill. A size on size end mill (1/4" in a 1/4" slot) would give poor results at that length. The cutting forces will tend to pull or deflect the cutter. If you’re deflecting away from one wall of a slot, your deflecting into the other wall. So you cut it undersize down the middle, then clean up the walls.
I’m a machinist by training and now sell cutting tools for a living. Carbide is my friend and my bread and butter. I still futz around in a shop making beer money with a friend.
Coolant, coolant, coolant is the biggie with Al. First, use a two flute end mill to help with the chip load. Coolant keeps the tool from bugging up. The Al will build up quickly on the cutting edge of the tool and cause a lot of drag. This could be why you broke a lot of tools. In a CNC I’d use pure cutting oil. For an open Bridgeport like manual machine I use a water soluable coolant. If the machine doesn’t have a coolant sump here’s what I did. I took a pump up bug sprayer and hold the nozzle in one hand while turing a wheel with the other.
In a pinch use WD-40. Any lube is better than dry. (Hmmm interesting advice that goes so well in many aspects of life.)
Take your time and make a bunch of shallow cuts back and forth. Do not try to do it all in one pass at 1" deep. Medium to high RPM’s and go gentle on the feed rate.
Any more details? Got a print handy?