Fly cutting titanium

REK Knives

REK Knives

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Knifemaker / Craftsman / Service Provider
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Looking but can't find the recommended SFPM for Ti w/ a hss fly cutter insert... any recommendations on how to go about doing this? I need to remove about .060" for a backspacer. If I can figure out the recommended cutting speed I was going to use the formula 4 x the cutting speed, divided by the cutting tool diameter (probably 2.5" on my fly cutter) as this formula was recommended by Tom's Techniques page anyway.
 
I would use about 100 SFPM. I think any issue is going to be more related to the rigidity of the fly cutter than anything. It might be painfully slow. Why fly cut such a small area? I did something similar but used a 1/2" endmill for a backspacer then just touched it clean on the disc sander. ETA: Unless you're going to do a whole plate, then cut spacers out of it. That makes sense.

Edit #3: Face mills make life easier for hard to cut things like this, even in a less than rigid setup you can just remove all but 1 insert and have a much more rigid tool.
 
kuraki said:
I would use about 100 SFPM. I think any issue is going to be more related to the rigidity of the fly cutter than anything. It might be painfully slow. Why fly cut such a small area? I did something similar but used a 1/2" endmill for a backspacer then just touched it clean on the disc sander. ETA: Unless you're going to do a whole plate, then cut spacers out of it. That makes sense.

Edit #3: Face mills make life easier for hard to cut things like this, even in a less than rigid setup you can just remove all but 1 insert and have a much more rigid tool.
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Thanks for chiming in man! That's a good point about the 1/2" endmill... from my research, if I go w/ the 1/2" carbide endmill I will want the SFPM about 135ish (1030 RPM), high feed, lots of coolant. Does that sound right?

Yeah I curious about he fly cutter though because I want to get the fly cutter thing for doing bigger sheets at some point, so why is a face milling cutter more rigid than a fly cutter?
 
Face mills just have more material supporting the cutter than a typical fly cutter with a 5/16" square tool in it, unless it's choked way up. Fly cutting works better the more free cutting the material is, and the springback/resistance Ti has makes me think it will cause chatter with that kind of setup - but I don't know that. It's going to be quite slow even if it does work. Now, if you made a purpose built fly cutter instead of the angled set screw jobbies that are common, with just a full diameter round and a slot in the outside, and just enough cutter hang out to make your depth of cut, that might work pretty well.

Your 1/2" carbide speed is roughly what I did. But I did it dry. Anything but flood coolant is generally not recommended with carbide and it cuts fine dry.
 
What alloy? CP/Grade 2 is a COMPLETELY different animal to machine than 6al4v (grade 5) titanium.

For 6al4v (which I could go on and on as to why it's a poor choice for knifemaking for anything other than components which need the "spring" aspect of this alloy), to get good finishes you need to take a heavier per tooth load cut, typically, lower spindle speed with a heavier feed. All this assumes your machine can handle it though, rigid with plenty of HP for the heavier cut.

Otherwise yeah, i'd try a face mill, and take a pretty shallow DOC, but feed fast. Remember, more radiused edge tools will give a better cut finish, but can't take as heavy a cut.

You'll need to experiment. On my bigger mill I would probably take the entire 0.060 in one cut, and expect that to give me the best surface finish with ti using a large face mill with pretty heavy corner radius inserts. If you're using a smaller mill, you may have to take 40 thou with a sharper cutter, then the final 20 or so with something else with corner radius.

Yeah, if you don't have coolant, use AlTiN coated carbide, it's designed to be run dry. Otherwise, you can rig a large food service pan (deep) with a couple holes drilled in the bottom and gaskets for a vise to sit inside, and cut titanium completely submerged in water or coolant, which is a pain in the ass to setup, but can offer some big advantages.
 
Like they said, a single insert face mill is a better bet over a fly cutter.

Honestly a fly cutter isn't good for much.

I recommend an insert designed for stainless steel or even aluminum. A relatively shallow depth of cut and a relatively High feed per tooth and relatively low surface feet per minute.
 
Alec Steel just had a video where he machined titanium. I can't remember the speeds (sorry) but he said it went better when he went to higher rpms.
 
Ian Fifelski said:
Alec Steel just had a video where he machined titanium. I can't remember the speeds (sorry) but he said it went better when he went to higher rpms.
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If that is what he said it is possible that he might not know what he's talking about. Titanium, as a general rule, is not machined at higher surface feet per minute. I'm not saying there aren't instances where it's done, but for most people titanium is milled fairly slow SFM.
 
Ian Fifelski said:
Alec Steel just had a video where he machined titanium. I can't remember the speeds (sorry) but he said it went better when he went to higher rpms.
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What exactly do you think qualifies Alec Steele to be giving advice on advanced machining? He's basically just a youtube celebrity at this point.

The rise of this kid's popularity amazes me honestly. Although I met Brian Brazael back when Alec was pretty much living with the dude, learning to strike and forge, which nobody seems to remember now (although search youtube for brian brazael alec steele and you'll see plenty of evidence what I'm saying is true), with seemingly no credit what so ever, being given, where due. They must have fallen out or something, but it's pretty fucked up considering the entire foundation of this kid's skill (and subsequent popularity) as a smith, was built on that relationship. Hell I only worked with Brian a couple of weeks, and I can't begin to tell you how fundamental even that little bit of time was to my skill and philosophy as a smith.


Regardless, I wouldn't take advice from either of them on machining. It's like asking a sail maker how to fabricate a go cart frame. He may be great at what he does, and he'll probably have opinions, but one thing has jack shit to do with the other. :P



LOL, sorry to derail your thread Josh.
 
javand said:
What exactly do you think qualifies Alec Steele to be giving advice on advanced machining? He's basically just a youtube celebrity at this point.

The rise of this kid's popularity amazes me honestly. Although I met Brian Brazael back when Alec was pretty much living with the dude, learning to strike and forge, which nobody seems to remember now (although search youtube for brian brazael alec steele and you'll see plenty of evidence what I'm saying is true), with seemingly no credit what so ever, being given, where due. They must have fallen out or something, but it's pretty fucked up considering the entire foundation of this kid's skill (and subsequent popularity) as a smith, was built on that relationship. Hell I only worked with Brian a couple of weeks, and I can't begin to tell you how fundamental even that little bit of time was to my skill and philosophy as a smith.


Regardless, I wouldn't take advice from either of them on machining. It's like asking a sail maker how to fabricate a go cart frame. He may be great at what he does, and he'll probably have opinions, but one thing has jack shit to do with the other. :p



LOL, sorry to derail your thread Josh.
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I heartily agree! He is surely no pro machinist.

It just looked and sounded better when he ran it at a higher speed in the video.

Nathan the Machinist said:
If that is what he said it is possible that he might not know what he's talking about. Titanium, as a general rule, is not machined at higher surface feet per minute. I'm not saying there aren't instances where it's done, but for most people titanium is milled fairly slow SFM.
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That's what I thought, but like I said, in the video it ran better after speeding it up.
 
On the tormach 440 using their super fly I have used 3500 rpm, doc around .04 or so, 7ipm for finish, 15-20 rough cut successfully in ti
 
thanks for all the input guys, I got that thing milled down w/ a 1/2" carbide end mill then touched it quickly on the disc sander and it's good to go! pic below

But, Javan, you Nathan, and kuraki have totally convinced me to return this thing (that's what I love about mcmaster carr!) and get a face mill instead. So something like this? Would the round or octagon carbide inserts be better for this? And basically I would want to dry mill (I do have a fog buster but that's not enough coolant??) correct?

i-tfH8f3P-X2.jpg
 
You can't go wrong with mcmaster typically Josh, but I wanna recommend you checkout https://latheinserts.com/main.sc

The owner is a member over at PM boards, who is very helpful, and has consolidated a lot of indexable tooling on his site, specifically for manual machines, as opposed to CNC. Much indexable (tools that take inserts) tooling, is designed for setups far beyond what our machines are capable of, many of the relief angles and rakes of inserts don't work well in these situations. It's why you'll see blanket statements all over the place recommending to not use indexable tooling with manual machines, especially lathes.

On top of all that, the inserts options, can be insane, with absolute no standardization across manufacturers, even just in regards to their codes. They all want to sell you something proprietary and different than the next guy, even if they're functionally the same, to get you hooked on their stuff.


I've had good luck with, and seen nothing but great reviews from anything he sells, he offers curated, limited options, to fill the primary scenarios/uses of general machining, and premium, limited, and explained options on inserts for each. i.e. buy these inserts for steel, buy these for aluminum, etc, all at good value propositions (price vs performance). There's information about what to buy based on what size and config machine you have also, and he's got appropriate sized stuff for most hobby/enthusiast level machines.

Yes, you could buy surplus tools, and get inserts, etc, if you really know what you're looking for, but I'm here to tell you that, the level of confusing options, makes understanding manufacturers codes for surface grinding stones, seem as simple as marking X for your name. You might as well be trying to read Japanese without any practice or experience. ;p

Check it out before you buy anything from McMaster, and let us know if you have any questions.
 
What mill are we talking about here btw? That'll give us a better idea what you can swing successfully.


Edit to add: I think it's important to mention that if we're talking about a bench/stand mill, a 3" face mill of any type you're really not going to have the ass to run, and if you don't need to rip down wide stock, probably don't make much sense.

There are smaller R-8 shaft indexable end mills, and some specialty 2" face mills that work with lower HP, that you may be able to utilize, but whether it makes economic sense, will depends on the specifics.
 
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Also, that face mill you linked from McMaster looks nice, especially from a versatility standpoint, but I can't find any indication as to what size and configuration of inserts it holds.

Square round or octagonal, but, unfortunately, there are tons of sizes, and even specific shapes, and configurations of these seemingly simple geometries.
 
Nice!

Agree, tell us the mill and we'd be happy to recommend a cutter. I may have surplus ones at work that haven't made it to Ebay yet.
 
I'm serious let me check I think I have something for you. All you'd need is an R8 adapter. $30 from Shars or whatever. I'll check and if I don't, I'll look into the link.
 
kuraki said:
I'm serious let me check I think I have something for you. All you'd need is an R8 adapter. $30 from Shars or whatever. I'll check and if I don't, I'll look into the link.
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Awesome thanks!
 
Is there one you would recommend for a straight shank collet holder? Have been working on fly cutting stainless, but either my bit profile or cheap fly cutter frequently gives me problems. I have a tired old toolmaster 1b that usually works..
 
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