Best way to mill 13" hole 6.5" deep in 4140

[Vancbiker]

Place I worked at in the late 70s ran spade drills up to 6” and we had one job using an 8” c’bore with a 4” pilot. Chips off that tool often won the contest of who could hang onto the chip hook better, man vs chip.

 

[mhajicek]

Sink EDM...

 

[CAMasochism]

13" diameter flat bottom drill? G83?

Which of your vices do you recommend to hold the part?

 

[dandrummerman21]

alright guys, she's done.

Nothing spectacular happened, just the same as the first time. lots of chips, lots of time, done.

The program ran about 3.5 hours. For the last inch I had a guy using a magnet to pull chips as it goes.



I love how dependable in unfavorable conditions feedmills are. no chipping of the cutting edge, and not a terrible amount of wear to the inserts when done. I don't know if I could run the program again without flipping at some point in the middle, though.

By the end the spindle was at about 115% spindle load during ramp, as opposed to 90-100 when i started.

But for the majority of the 3.5 hours, it was walk away for a few minutes doing other crap, and then come back to pull out chips for a few seconds.

I wish i had taken pictures of the huge pile of chips...

 

[Orange Vise]

I love how dependable in unfavorable conditions feedmills are. no chipping of the cutting edge, and not a terrible amount of wear to the inserts when done.

Yup, sounds terrible with the chip recutting but they just keep plugging away.

 

[mhajicek]

I love how dependable in unfavorable conditions feedmills are. no chipping of the cutting edge, and not a terrible amount of wear to the inserts when done.

Yup. I've gotten ten hours out of a 3mm high feed in Titanium.

 

[dandrummerman21]

Yup. I've gotten ten hours out of a 3mm high feed in Titanium.

3mm? I wasn't even aware they went that small. I'd seen somewhere in the half inch range. But I've never gone looking for such a small tool either.

 

[TeachMePlease]

Yup. I've gotten ten hours out of a 3mm high feed in Titanium.

Can you give details on this 3mm feed mill?

Because that gets down into a size range I could potentially apply. Not that I have an application for it, as of yet, but I rather like tooling and knowing my options.

 

[dandrummerman21]

Can you give details on this 3mm feed mill?

Because that gets down into a size range I could potentially apply. Not that I have an application for it, as of yet, but I rather like tooling and knowing my options.

Yeah I wouldn't mind knowing more suppliers.

The first link i came up with on google:

High Feed End Mills

goes down to 1/8 and 3mm it seems.

 

[Phil in Montana]

You are so badly out gunned tring to do this in house it hurts, just the tooling cost alone would kill the profit...find a shop with a vtl or a hbm and sub the job out...Phil

 

[implmex]

Hi Phil in Montana:
You wrote:
"You are so badly out gunned tring to do this in house it hurts"

Interesting point of view that I don't fully understand.
The OP says he has large equipment available that is up to the task, but the best machines he could use are all booked up.
He says so in his very first post.

So he doesn't sound to me like somebody trying to do a stupidly over ambitious job on a totally inadequate machine...it sounds more like he's trying to find a way to solve a temporary problem with the resources he has which are well within the range of reasonable for his needs, including this one.

I get that there are some posters (mostly newbies or hobbyists with little experience) that ask "how to do" questions showing that they have no idea what this takes, and sometimes I have to roll my eyes too...our OP does not seem to fall in that category by any stretch.

Now I have no idea what his shop actually looks like or what he has in it.
Do you?

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

 

[mhajicek]

Yeah I wouldn't mind knowing more suppliers.

The first link i came up with on google:

High Feed End Mills

goes down to 1/8 and 3mm it seems.

Yep, those are the ones.

 

[dandrummerman21]

You are so badly out gunned tring to do this in house it hurts, just the tooling cost alone would kill the profit...find a shop with a vtl or a hbm and sub the job out...Phil

I mean, I would have preferred it be done in our lathes, but we're trying to expedite the parts for this customer, and I did have the means. I posted the question because I was looking for others' ideas on how to get it. Because contrary to what I'd like to believe, I don't always think of all of the options myself. Sometimes there's better ideas than what I thought of.

Ultimately I went with the option that I'd already completed on a similar part, and it worked. But maybe there was some method that'd be obviously better. I really liked the idea of high speed milling in steps, leaving more on the walls for every pass. If I didnt have a big 50 taper machine that could drive the 5" feedmill that the shop already owned from a past job, and I had to do it in a 40x20 40 taper machine, I think that would have worked very well for me.

We have a big 50 taper horizontal that I think the same method I used would have worked so much better in. 40hp makino a88. But that machine was, and still is, very busy.

And it only took an hour to get it on the machine, clamped in and probed. And 3.5 hours to run. add another hour to clean up all the chips. Can round it up to 8 hours if we want. Would the lathe be an hour? two? The time it would take to stop the current job running there, switch jaws and tools, run these 3 similar parts, and then set back up to finish current job while parts are at HT would take more than the time I spent fussing.


Did I mention already that I had finished milling the part?

 

[Mtndew]

Can you give details on this 3mm feed mill?

I get my small ones from Garr.

https://www.garrtool.com/doc/pdf/H45.pdf

 

[DDoug]

Good to read that you got the job done.

How did you manage the salad bowl full of chips ?
Stop every 5 minutes or so and use the shop vac ?

 

[dandrummerman21]

Good to read that you got the job done.

How did you manage the salad bowl full of chips ?
Stop every 5 minutes or so and use the shop vac ?

We have a magnet that looks similar to this:

MAGNET SOURCE Retrieving Baton':' Magnetic, 1 in, 16 in Lg, 1 in Wd, 1 in Dia, 1 in Surface Size - 38HY91'|'RHS02 - Grainger

Stick it in the hole, pull out chips, then pull the rod on the end. The magnet inside slides up and down and when it hits the shield on the wand, the chips fall off.

The machine is going "slow" enough to do it while it's cutting. I ended up with flood coolant to make the chips more buoyant to reduce the number of chips that get recut. The coolant also helped the tool kinda push chips up and over the edge of the part.

Hi Phil in Montana:
You wrote:
"You are so badly out gunned tring to do this in house it hurts"

Interesting point of view that I don't fully understand.
The OP says he has large equipment available that is up to the task, but the best machines he could use are all booked up.
He says so in his very first post.

So he doesn't sound to me like somebody trying to do a stupidly over ambitious job on a totally inadequate machine...it sounds more like he's trying to find a way to solve a temporary problem with the resources he has which are well within the range of reasonable for his needs, including this one.

I get that there are some posters (mostly newbies or hobbyists with little experience) that ask "how to do" questions showing that they have no idea what this takes, and sometimes I have to roll my eyes too...our OP does not seem to fall in that category by any stretch.

Now I have no idea what his shop actually looks like or what he has in it.
Do you?

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

The next time I post a question relating to how to do a somewhat difficult job, It'll be like this:


"I've got to mill a 13" hole in a piece of 4140. How fast should I run my 5" feedmill on my speedio? I tried 15000rpm but the tool didn't last very long"

 

[mhajicek]

I get my small ones from Garr.

https://www.garrtool.com/doc/pdf/H45.pdf

The PDF says "HIGH FEED ENDMILLS", but what it shows and describes seem to be standard corner radius endmills. Do they have the high feed profile on the bottom?

 

[DDoug]

The coolant also helped the tool kinda push chips up and over the edge of the part.

Very nice with the magnet.

Sounds like this would be the one time where foaming coolant would be a plus.....it sounds like that would have carried most of the chips up & over the rim.

 

[Mtndew]

The PDF says "HIGH FEED ENDMILLS", but what it shows and describes seem to be standard corner radius endmills. Do they have the high feed profile on the bottom?

I just looked at the 1/8" under my magnifier, it has a small flat on the bottom of the flute. So, not the "typical" angle lead that I can see. But maybe because it's such a tiny profile?
I have a repeat job where I use them as high feed mills and they hold up really good in 4150pht.

 

[Phil in Montana]

My point was the machine he wants too use is to small to do the job in a profitable manner, and whats the point if you do not have a gain, just sub it out to a shop that has open time and the right machine , or better yet buy a lathe and have it for next time if it has to be done in house...Phil