Which end mill to use

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Mr Ron
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Re: Which end mill to use

Post by Mr Ron »

GlennW wrote: Fri Aug 23, 2019 2:37 pm
Magicniner wrote: Fri Aug 23, 2019 12:25 pm
SteveM wrote: Fri Aug 23, 2019 10:22 am What are the advantages of three flutes vs two or four?
Polished TC fast helix 3 flutes are pretty much optimum for ally cutting if your machine has the speed, feed and rigidity to use them, more flutes than 2 allows faster feeds and they don't gum up like a 4 flute will if you run optimum speeds.
Additionally:
Three flutes also cut a slot that is on size, and run quieter and smoother than a two flute, leaving a better finish.
Thank you for your input. Sounds good to me.
Mr.Ron from South Mississippi
thunderskunk
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Re: Which end mill to use

Post by thunderskunk »

https://www.maritool.com/Cutting-Tools- ... _info.html

Roughing end mills are a lot more forgiving feed/ speed wise (In my humble opinion, feel free to interject), and if you get one with more flute length, you can stack your parts and rough a few at a time. Someone suggested predrilling, I’d do that too. They’re not free, but if it’s something you’ll use more than once it’s a great investment.

You can always run a finish pass one part at a time all said and done.
"We'll cross that bridge once we realize nobody ever built one."
Mr Ron
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Re: Which end mill to use

Post by Mr Ron »

This project is a paying project and it has taken more time than I wished. Off course the weather has been a factor + my age is slowing me down more than I like. The project pays $400 and that will help a lot in bolstering my SSI check. This project could blossom into more future work for me.
Mr.Ron from South Mississippi
Mr Ron
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Re: Which end mill to use

Post by Mr Ron »

I used the 1/4" 3-flute end mill and went through the 20 aluminum 1/8" plates like butter. I found that running the end mill in a CCW direction, (climb milling) left a smoother interior finish on the openings which were 1/2"x1-1/4" and 1"x1-1/4". Milling in the CW direction left a rough finish. I also took the advise of Bill Cook and plunged and then used the upper portion for cutting. I also did it all without a coolant. All told, there were (80) openings to cut, using 1/4" and 1/8" bits along with (1200) 1/16" and 1/8" diameter holes, but I was able to gang the plates, 4 at a time to drill the holes. I did all the work on my vertical mill with the newly installed DRO. I am very pleased with the results. I think the entire job from start-to-finish took me about 20 hours over a period of 4 days.
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Harold_V
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Re: Which end mill to use

Post by Harold_V »

Mr Ron wrote: Mon Sep 02, 2019 2:28 pm I also did it all without a coolant.
Working without coolant is acceptable, but you'll accomplish a much nicer finish by (acid) brush applying a little lubricant. It helps prevent chip welding, and allows the generated chips to evacuate easier. For aluminum, kerosene works extremely well, as does WD-40, but even solvent (Stoddard, paint thinner, mineral spirits) with a little oil dissolved within work well, and for ferrous, sulfur based cutting oil. In all cases, surface finish will be improved.

H
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BadDog
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Re: Which end mill to use

Post by BadDog »

Harold mentions "acid brush", but I always knew them as "flux brushes" (same thing being typical flux is acid based).

They cost nearly nothing from HF, Amazon, or whatever your preference. They also usually have tubular metal handles, so you can even rig up a distribution system using that handle as a tube rather than constantly dip-n-dab. I keep a bunch on hand and use them for everything including from cutting/lube oil to wood glue application/spreading. A box of "pipets" is likewise very cheap and very handy, and a stack of the little small disposable mixing cups...

But as I've said in many other posts, for my cutting (or other) fluid application uses, I mostly use inexpensive laboratory "wash down" bottles for most everything. I've got several of varying sizes that contain distilled water, WD40 from a bulk can, light cutting/tapping fluid, heavy sulfurized cutting fluid, ISO-22, ISO-68, Vactra 2, cheap ND 30W motor oil, and a bunch of new bottles setting for whatever else crosses my mind. If I need a very fine controlled stream, use as they come. Need a heavier flow, or for heavier more viscous fluids, cut the tip back a bit. You don't have to invert to use, you can tip at any angle more or less upright and function, and/or bend the tubes, and they don't leak... unless you leave the top sealed and it becomes an impromptu barometer that pushes fluid out when the baro pressure drops.

And remember that tubular handle on the flux brushes. The larger 8 oz wash downs I have work great for just stuffing that tube onto the tube for a steady feed that wicks along the brush, though the original upward angle of the bottle nozzle will cause backflow mess if not addressed.

But one thing to remember when applying is to NOT squirt it during the cut unless you maintain a steady stream. If you do, you can shock the hot cutting edge and ruin it right quick. It's either apply and cut, or maintain flow like flood for the entire cut. However, if you can keep the tiny flow in the cut, you can simulate flood for important (like finish) passes while only generating a moderate cleanup puddle. I find that generally easy on the lathe because I can brace it off the saddle to keep the flow in the cut as it traverses by simply maintaining a gentle squeeze, but more difficult on the mill, particularly if not using power feed. As such, I almost never do that, but can if needed.
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Mr Ron
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Re: Which end mill to use

Post by Mr Ron »

Although I didn't use any coolant, I didn't get any chip weldment after cutting almost 16' of 1/8" aluminum, 6061-T531. The end mill I used was a 3 flute TiCN coated bit. The plates I cut were for a leather covered wallet so the openings won't show.
wallet.jpg
Mr.Ron from South Mississippi
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Harold_V
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Re: Which end mill to use

Post by Harold_V »

The chip welding I'm addressing isn't necessarily obvious to the eye, but if you take a close look at the cutting edge, you may find there's a very thin deposit of aluminum. That can be avoided with just a little lubrication. The slight deposit is the reason for a diminished finish. Sounds like it wasn't of importance in this instance, but it's nice to know when it is.

I took note that you used an end mill with a finish. That finish may limit, if not eliminate, the welding I spoke of. I don't know. My experience with end mills came to an almost abrupt end in 1983, and much has changed since then.

Note that I still use end mills. I just don't buy them, with rare exception. I have a huge number, several of which have never seen use, all left over from my years of running my machines for gain. Precious few of them have any kind of finish, so my experiences are from the old days.

Interesting project. I'd enjoy seeing the finished work. Maybe you could post a picture or two?

H
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Mr Ron
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Re: Which end mill to use

Post by Mr Ron »

Thank you Harold for your reply. I have problems trying to post any attachments to my posts. I have an old XP computer that acts up on me producing erratic results. I was surprised that I could attach the sketch of the metal plate, but I will keep trying.

Again, you have given me new information to file away in my brain for future use.
Mr.Ron from South Mississippi
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GlennW
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Re: Which end mill to use

Post by GlennW »

The coating on your end mill, (TiCN) isn't particularly desirable for aluminum. Aluminum tends to adhere to Titanium Nitride coatings. Zirconium Nitride (ZrN) would be a better choice if you need a coating, but even then, it works best at very high speeds.
Glenn

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Harold_V
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Re: Which end mill to use

Post by Harold_V »

What Glenn added is the very thing I don't know. Thanks, Glenn. Now if only I could remember what you said when it matters. :oops:

H
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Mr Ron
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Re: Which end mill to use

Post by Mr Ron »

GlennW wrote: Tue Sep 03, 2019 1:22 pm The coating on your end mill, (TiCN) isn't particularly desirable for aluminum. Aluminum tends to adhere to Titanium Nitride coatings. Zirconium Nitride (ZrN) would be a better choice if you need a coating, but even then, it works best at very high speeds.
Thanks Glenn for the information. I would not learn this in school or in a book.
Mr.Ron from South Mississippi
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