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Roughing V Finishing Endmill final finish

M

MRudisill

Plastic
Joined
Jan 13, 2020
So having a heck of a time finding images or video comparing the two.

Making prototype parts, so its not essential to have the perfect mirror finish. More of a proof of concept normally. My question is, before I run this massive material clearing part, how rough of a finish does a 'roughing' endmill leave? Is it still fairly smooth, but just not a mirror finish, or is it pretty awful and going to want a finish endmill to do a final pass?

It's a very small shop, slowly gettings the tooling we need as we need them, and the long finish end mill we have is pretty garbage, so wondering if the nice new carbide roughing mill will work for now, or if it's going to be a pretty big deal to replace the finishing endmill for these parts.

And before anyone goes on this rant, yes I know it's an expensive trade, and bits are always worth the money yada yada. We are a small shop, COVID stuff hit everyone, so just kind of toying around with things as we slowly get all the ideal tooling over time.
 
Are you asking about a 'roughing' end mill (like a corncob), or a finish endmill with a chipbreaker? If the latter, it will leave a decent (subjective of course) finish, a corncob will definitely want to use a finish endmill afterwards.
 
Often, a Roughing Endmill is identical to the Finisher. They are different designations for cut parameters, tool pots, and predictability. Those godamned corn cob POS can stay in the "70's. AFAIK.

R
 
Cole2534 said:
I want to try one of those in comparison to a Mari unit of similar design. What are you paying for one?
Click to expand...

Those end mills are certifiably bad ass. We just went through a bunch of the 7 flute .625 and .500 diameter ones. I think the 1/2" were around $100 and the 5/8" around $130.

We used them on 13-8 and 17-4 SS that was heat treated to anywhere from about 38Rc up to 60Rc. Talking serious improvements on both tool life and runtime against the first revision we machined a few months back.
 
dodgin said:
Those end mills are certifiably bad ass. We just went through a bunch of the 7 flute .625 and .500 diameter ones. I think the 1/2" were around $100 and the 5/8" around $130.

We used them on 13-8 and 17-4 SS that was heat treated to anywhere from about 38Rc up to 60Rc. Talking serious improvements on both tool life and runtime against the first revision we machined a few months back.
Click to expand...
I got my ass handed to me by some 304 the other day, maybe I'll reach out for one of these next time.

Sent from my SM-G981V using Tapatalk
 
It is a carbide 'corncob' rougher. May I ask why those are not ideal?

For what it's worth we are 98% cutting 6061 aluminum.
 
MRudisill said:
It is a carbide 'corncob' rougher. May I ask why those are not ideal?

For what it's worth we are 98% cutting 6061 aluminum.
Click to expand...

Absolutely the wrong tool for any Aluminum.

BUT names of things are often not the same as mental images, descriprions change from person to person. If you're talking about this---08-598-080.jpg then it's great for Aluminum.

OTOH, if you're talking about this----drill-america-specialty-drill-bits-dwc1-1-8-64_1000.jpg It's the wrong tool for Aluminum.

Aluminum needs to get moved, not ground up into tiny chunks. BUE and remnant chips are welding materials in that case.

R
 
litlerob1 said:
Absolutely the wrong tool for any Aluminum.

BUT names of things are often not the same as mental images, descriprions change from person to person. If you're talking about this---View attachment 293581 then it's great for Aluminum.

OTOH, if you're talking about this----View attachment 293582 It's the wrong tool for Aluminum.

Aluminum needs to get moved, not ground up into tiny chunks. BUE and remnant chips are welding materials in that case.

R
Click to expand...

Well definitely good to know. Newer to the field so still learning all these little ins and outs. I can do some good pathing and speeds and feeds but ideal tooling then coatings and all that are things I am working to better understand.

I ordered a carbide 'corncob' the second style you linked there to do some roughing. We have some deep walls (about 2") and pockets and the first part I had to make due with a HSS finishing endmill that was pretty awful. So I assuming this will at least be an upgrade from that and moving forward can work towards getting those other bits.

You say aluminum needs to get moved, from what I have seen making sure to run at as high of RPM as I can really helps to project those chips out. Am I correct to assume that the corncob just creates a crazy amount of smaller chips that tend to fall rather that fling if that makes sense? Would maxing or backing of the chip load help since I will have to run at least a couple parts with the corncob style?
 
Cole2534 said:
I want to try one of those in comparison to a Mari unit of similar design. What are you paying for one?
Click to expand...

Just checked. $98.00 for a 5-flute 1/2 x 1.625 w/ .030 CR.

This one was a special because I got them to put their best coating on, the T-plus. With the standard A-plus (which is still good) they're more like $90.00.

MRudisill said:
......Am I correct to assume that the corncob just creates a crazy amount of smaller chips that tend to fall rather that fling if that makes sense?
Click to expand...

Yes. Chipbreakers are for long endmills or deep slotting in steel where chip evacuation is horrible.

For heavy profiling with a 1" LOC endmill I would use a standard solid carbide since the bigger chips do fine.
 
As Rob said, alot of times rough and finish are just designations for the operator or setup guy. You would use a slightly dull or used tool for roughing, and a new (or very good) one for finishing. Then when your rougher is not cutting too good anymore, switch th efinisher to roughing and grab a new one for the finisher, rinse nad repeat. However, on aluminum alot of people (we do alot) use the same tool for rough and finish, tolerances permitting.

No need for anything fancy with aluminum, either uncoated or Zrn is fine. Save the fancy coatings/geometries for your steel jobs.

Get 2 of these and you will be set for a long time (if you don't crash).

https://www.mscdirect.com/product/details/82976432
 
I sell Helical and they have great stuff. Pro tip that may actually hurt their sales is their high balance aluminum mills High Balance

I use to sell 6-10 3/8" 3 flute aluminum Helical endmills the 45 degree helix ones to a client who does some pretty serious roughing on aluminum carburetors for a certain track racing series. They make these all day 5-6 days a week, 2 ops at a time on a trunnion table.

I had him try out 2 of the 3/8" high balance coolant through 3 fluters. He ran one of them for 6 months! So he went from spending $250-$300 a month to spending a little over $100 dollars for 6 months and pushed the tool faster. :crazy: Easily saved him $1,000 on a tool not to much the reduced cycle time.

Not going to lie I wasn't excited as maybe I should have been! Since I lost the sales but hey if you're not moving ahead you're getting passed behind and my customer was pretty happy with me:)

If anyone wants to try Helical and isn't currently buying it PM me and I will make you some sort of incentivized deal.
 
MRudisill said:
Am I correct to assume that the corncob just creates a crazy amount of smaller chips that tend to fall rather that fling if that makes sense? Would maxing or backing of the chip load help since I will have to run at least a couple parts with the corncob style?
Click to expand...

First question = yes
Second question = no, just flood the hell out of it to keep chips moving.

What machine are you running these parts on?
I would recommend this style for roughing and finishing aluminum. Get the ZrN coating or uncoated.
Square End 3 Flute High Helix End Mill Finishers - MariTool
 
litlerob1 said:
Absolutely the wrong tool for any Aluminum.

BUT names of things are often not the same as mental images, descriprions change from person to person. If you're talking about this---View attachment 293581 then it's great for Aluminum.

OTOH, if you're talking about this----View attachment 293582 It's the wrong tool for Aluminum.

Aluminum needs to get moved, not ground up into tiny chunks. BUE and remnant chips are welding materials in that case.

R
Click to expand...
I am in total disagreement with you on this. I found rougher/finishers to be a total waste of time, I still have a few NIB from close to 20 years ago when I tried them out, Destiny Diamondbacks with their stealth coating. NOTHING works like a corn cob rougher. They remove more material using less HP with less cutter pressure and far less lift than any other type of end mill I have tried. How fast I can machine a part is generally limited by how well I can hold onto it so corn cob mills are my main roughers for many parts, and if you ever have to slot they are over twice as fast. Another benefit is the chips take up about 1/4 of the room as what a normal end mill makes. Other than the surface finish I can't think of a single thing that is negative about them. Keeping in mind the op is mainly machining 6061. For finishing Harvey makes some very nice 5 flute finish mills, that have become my standard. I am not saying they are best for everything but they do belong in your toolbox of good ideas.

If your chips are too small maybe you feeding them like a normal end mill. Chip loads are much higher with corn cob mills, 3/8" go around .035" and 1/2" around .05". A good coating is well worth it IME, I can run coated tools around 20% faster and they last several times longer vs uncoated.
 
DavidScott said:
I am in total disagreement with you on this. I found rougher/finishers to be a total waste of time, I still have a few NIB from close to 20 years ago when I tried them out, Destiny Diamondbacks with their stealth coating. NOTHING works like a corn cob rougher. They remove more material using less HP with less cutter pressure and far less lift than any other type of end mill I have tried. How fast I can machine a part is generally limited by how well I can hold onto it so corn cob mills are my main roughers for many parts, and if you ever have to slot they are over twice as fast. Another benefit is the chips take up about 1/4 of the room as what a normal end mill makes. Other than the surface finish I can't think of a single thing that is negative about them. Keeping in mind the op is mainly machining 6061. For finishing Harvey makes some very nice 5 flute finish mills, that have become my standard. I am not saying they are best for everything but they do belong in your toolbox of good ideas.

If your chips are too small maybe you feeding them like a normal end mill. Chip loads are much higher with corn cob mills, 3/8" go around .035" and 1/2" around .05". A good coating is well worth it IME, I can run coated tools around 20% faster and they last several times longer vs uncoated.
Click to expand...

So post some feeds speeds and doc you use with a corncob please.
 
DavidScott said:
I am in total disagreement with you on this. I found rougher/finishers to be a total waste of time, I still have a few NIB from close to 20 years ago when I tried them out, Destiny Diamondbacks with their stealth coating. NOTHING works like a corn cob rougher. They remove more material using less HP with less cutter pressure and far less lift than any other type of end mill I have tried. How fast I can machine a part is generally limited by how well I can hold onto it so corn cob mills are my main roughers for many parts, and if you ever have to slot they are over twice as fast. Another benefit is the chips take up about 1/4 of the room as what a normal end mill makes. Other than the surface finish I can't think of a single thing that is negative about them. Keeping in mind the op is mainly machining 6061. For finishing Harvey makes some very nice 5 flute finish mills, that have become my standard. I am not saying they are best for everything but they do belong in your toolbox of good ideas.

If your chips are too small maybe you feeding them like a normal end mill. Chip loads are much higher with corn cob mills, 3/8" go around .035" and 1/2" around .05". A good coating is well worth it IME, I can run coated tools around 20% faster and they last several times longer vs uncoated.
Click to expand...

You use corn cob to Rough and a 5 flute to Finish in Aluminum? Jeesus everything about that against popular vote. Not saying it's wrong, just noting it.

R
 
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