Looking for thoughts on material for project

[RaisedByWolves]

Hobby guys tend to overthink things.......

I was afraid to make this reply due to hurting someone's feels lately, as sometimes they also underthink.

Guys in industry tent to "Run what you brung" or, found laying in the scrap heap.

I think at least part of the overthinking on the home shop guys part is 1: Lack of experience in just doing it, and 2: having to shell out the cash for a suitable material and not wanting to have a "do over".

We have a lot of A2, O1 and some D2 along with lots of mystery metal at work. The piece I made my mill column base out of was chosen because it was the appropriate size, but it was just cut from a piece of leftover 4"X6"X 87" barstock sitting in the corner. Hardest part of that decision was how to get it into the saw to get a hunk cut off of it. Had to be 500lbs.

Having scrap A2 and the ability to harden it makes this a no brainer choice, and some items get heat treated and drawn back to what I want and others can be left soft. o1 is another choice along these lines whereas the D2 gets saved for if there is a need for extreme toughness when hardened or something that you would not want to rust.

Short of getting some cast iron shafting and not realizing what it is I think most shop made projects will be fine with whatever is at hand.

If what I read above about pressing it into 6061 is true the last of your worries are with the steel.

 

[RaisedByWolves]

Those are alloy steels that have a lot of strength. They machine and grind better than mild steel, and are low on internal stress. It doubles the price of any project to use 41x0, etc. It would be my preference too, if it's available. But your fly cutter isn't going to need any strength beyond what the press fit and alloy body can provide. Weakest links being what they are.

Fly cutters can really get hammered overlapping cuts and interrupted cuts. The moment a fly cutter touches the work, it's a hard life of whup-whup-whup, a rhythm that is going to ripple and flex that alloy disc and amplify harmonics as the vibration chatters your work like a fat chick in a coin-op relaxo bed.

I have a fly cutter that I like an awful lot. It's like 7.625" pass width, and the base plate is 3/4" steel and uses a simple 3/4" stud for an R8 collet. It's kind of a no-brainer design. They're made by Flexbar now, and would be easier to make than the one you have planned.

Another thing to be cautious of when using the smaller machines is if they have plastic gears in the head when using a fly cutter or really any type of repetitive interrupted cut.

You can get the system (Machine gear and tooling) into a rhythm that puts undue stress in one single pair of gear teeth which will cause them to fail. This happens when the single tooth, or a pair of teeth (It is really dependent on the number of teeth on the gears) come into contact just when or slightly after the cutter makes contact with the work.


I blew the sacrificial plastic gear out of our big supermax mill like this twice over a 20yr span. Both occurrences were with the same shell mill that would obtain the same rup, rup, rup, rup type cutting action. Don't know if it was a poor design on that cutter or if the mounting system was faulty, but there was no dialing it out and we quit using it.

Never blew out that gear again.

 

[RaisedByWolves]

Thanks John, I may save that aluminum for something else and build one of these, I like that design.

First time I saw someone making a fly cutter out of aluminum was on youtube and I thought it was interesting but dismissed it as I didn't care for that guys content. It was a single carbide insert on a 6" disk. Turned out to work well for him, but as I mentioned above, he's going to lose the gear in that machine.

IMO going with aluminum in a disk that size you are giving up the one thing a cutter like that has going for it, mass and inertia.

OK, that two things but you get the point. The double cut head John posted partially negates the need for the mass, but it still wouldn't hurt if you had a chunk of steel that size laying around.

 

[verbotenwhisky]

First time I saw someone making a fly cutter out of aluminum was on youtube and I thought it was interesting but dismissed it as I didn't care for that guys content. It was a single carbide insert on a 6" disk. Turned out to work well for him, but as I mentioned above, he's going to lose the gear in that machine.

IMO going with aluminum in a disk that size you are giving up the one thing a cutter like that has going for it, mass and inertia.

OK, that two things but you get the point. The double cut head John posted partially negates the need for the mass, but it still wouldn't hurt if you had a chunk of steel that size laying around.

No hurting my feelings, I have relativly thickin as long as people are not trying to make it personal, I appreciate the input.

I am looking for something to make large finishing face cuts with, .005 to .010, for surfacing, I actually have a 3" face mill. I follow the YouTuber Inheritance Machining and got the plans from him for the cutter I am working on although I may change directions.

I messed up when I described the design, It is an R8 connector with a flange which is why I was looking at the 1045, the 4140 I have is a bit too small in diameter for the flange, the R* connector/adapter has a 1" nub which is 1" long that presses into the aluminum disk and the flange has 4 counter sunk bolts which thread through from the face of the disk into threads cut into the flange; so the press fit isn't the only thing holding it. the original design uses a 9" Dia x 1" thick disk and the piece I have is 8.625"Dia x 2"Thick I thought about cutting it down to 1" and decided I felt better about the 2" as it should handle any deflection better. In addition the design I have uses a 4140 insert to hold the cutter while having a counter weight on the opposite side to help it with the mass and inertia issue. Another thing which I wonder about is using a carbide insert on the fly cutter, I always heard they didn't work well on interrupted cuts...

At this point I am very interested in the tool John showed me, but the more I look at it the more I think there is room for both in the tool cabinet.

I hope that makes me look a little smarter. I have some metal and I have a place to buy metal, when I can I attempt to make use of what I have.

 

[verbotenwhisky]

I really think the 2-cutter system is the ticket.

Here's mine acting busy:

View attachment 457082

Are you running that in an end mill holder?

 

[Parlo]

Take several passes with a smaller button insert cutter. Then take a couple of minutes with a random orbital sander & scotchbrite pad for a great uniform satin finish. This will save your spindle bearings and use the geometry of the machine to get a flat face.
p.s. If you insist making a flycutter please keep it round & keep the cutting edge inside the diameter as it becomes invisible when spinning.

 

[pontiac428]

I kept looking at it last night thinking about it, isn't .030 a pretty aggressive cut for a fly cutter? I love the idea, and I plan to have one....

I've taken repeated passes at .060 DOC in aluminum in a number of configurations using Mo-Max ground into a left hand profiling lathe grind and a tool tip of 1/16 radius, setting the cutting speed at the very bottom of the chart and working from there. It provides an excellent finish no matter what the rates, and you can really rip it if you want to. It gets a little loud and spooky, but the upper ceiling is way higher up than you'd imagine. I wouldn't hot rod it in steel like that, limitations of the Mo-Max, but it uses standard 3/8 brazed carbide (that's the recommended bit from the mfr) and could take insert holders if you really feel the need. Not that any thin carbide stands a chance in interrupted cutting, but that's where everybody wants to go.

 

[pontiac428]

Are you running that in an end mill holder?

In that picture, yes. I don't have any space constraints, so I like the EM holder. It makes it feel less crowded under the spindle compared to a collet, which works equally well.

 

[verbotenwhisky]

I've taken repeated passes at .060 DOC in aluminum in a number of configurations using Mo-Max ground into a left hand profiling lathe grind and a tool tip of 1/16 radius, setting the cutting speed at the very bottom of the chart and working from there. It provides an excellent finish no matter what the rates, and you can really rip it if you want to. It gets a little loud and spooky, but the upper ceiling is way higher up than you'd imagine. I wouldn't hot rod it in steel like that, limitations of the Mo-Max, but it uses standard 3/8 brazed carbide (that's the recommended bit from the mfr) and could take insert holders if you really feel the need. Not that any thin carbide stands a chance in interrupted cutting, but that's where everybody wants to go.

.060 is pretty impressive. I have been reevaluating the use of carbide, I like it but I broke and insert off rounding the end of a piece of 1018 square bar last weekend, Carbine really doesn't like to be slapped around....

 

[pontiac428]

Brazed carbide is a different beast. It's strong, tolerant, and grindable. It still reacts badly to unintended contact with the work piece during setup, we've all chipped it just barely touching something wrong. Then it can cost a workpiece too, chipped carbide tends to leave lousy finishes.

All the more reason to use HSS unless the job calls for more.