# face mill advice...



## gt40 (Mar 8, 2012)

After facing a 6"x 8" piece of D-2 steel with my pm45 mill with a 5/8" 6 flute end mill, I decided I need a proper face mill. The mill has a 3hp variable speed and is R8. I am looking at 45 and 90 degree indexable end mills in the 2-3" size. Is this the largest I should run and any thoughts on 45 degree cutters vs 90 would be appreciated. In the mean time, here is the best I could do on 55 rc d2 steel:


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## Th232 (Mar 8, 2012)

Not really much in the way of thoughts about 45 deg vs 90 deg, but have you considered a face mill that uses round inserts? The surface finish from mine is great.


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## wquiles (Mar 8, 2012)

We just had a recent thread on indexable mills that probably has what you need:
http://www.candlepowerforums.com/vb/showthread.php?334173-indexable-end-mills

Will


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## gt40 (Mar 8, 2012)

wquiles said:


> We just had a recent thread on indexable mills that probably has what you need:
> http://www.candlepowerforums.com/vb/showthread.php?334173-indexable-end-mills
> 
> Will



I saw the thread but only looked at the beginning. Good stuff there...


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## CKOD (Mar 8, 2012)

If youre getting an indexible cutter, do you have a surface plate/granite slab etc for thecking the alignment of the inserts? If they arent all even ,if definitely doesnt help flatness.


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## wquiles (Mar 8, 2012)

CKOD said:


> If youre getting an indexible cutter, do you have a surface plate/granite slab etc for thecking the alignment of the inserts? If they arent all even ,if definitely doesnt help flatness.



I completely agree on trying to get all inserts as level as possible, but the way I am looking at this, having inserts at slightly different alignments does nor affect the flatness, but rather the finish. Flatness would have more to do with the alignment of the cutter to the table (i.e., how level or trammed the cutter is respect to the spindle in the x and y direction).

In more detail: The finished surface height will be provided by the "tallest" insert - the one closest to the material being cut. As the cutter rotates that "high" insert does most of the work and sets the depth of cut, and therefore the finished height. If the inserts are not all even, what gets affected is the finish, since only 1 (or just a few of the high inserts) does the work, therefore wearing that insert(s) quicker, which again affects the finish.

Will


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## sionnach (Mar 8, 2012)

I love using the ceramic inserts, whatever the standard triangle ones are. Cheap and give a nice finish.
One thing I have seen, and may possibly benefit your piece there, is to double check the spindle to table alignment.
Then on your final pass (I do a "climb") at a super high spindle speed and the lowest feed rate I can get.
I also overlap the cut by 25 - 50%.


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## CKOD (Mar 8, 2012)

Good point, I had my verbiage wrong. Its definitely finish thats affected, which is just flatness at a really small scale :duh2: (thats my story and im sticking to it) If youre inserts arent level and youre feeding at a significant rate, you can see an arc for the path of each insert as it passed over the metal. But I'm more used to seeing them used as roughing cutters to bring stock down to size, where the feed rate is quite high, and they are running at something like .005 inch per tooth, iirc, and surface finish doesnt matter, since its gonna be cut down even further.


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## wquiles (Mar 8, 2012)

CKOD said:


> Good point, I had my verbiage wrong. Its definitely finish thats affected, which is just flatness at a really small scale :duh2: (thats my story and im sticking to it) If youre inserts arent level and youre feeding at a significant rate, you can see an arc for the path of each insert as it passed over the metal. But I'm more used to seeing them used as roughing cutters to bring stock down to size, where the feed rate is quite high, and they are running at something like .005 inch per tooth, iirc, and surface finish doesnt matter, since its gonna be cut down even further.



Ahh, yes, we were talking indeed about the same thing 

Taking a small cut and doing a slower feed will help, but it is even better if the inserts are fairly well aligned to start with.

Will


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## KC2IXE (Mar 8, 2012)

Th232 said:


> Not really much in the way of thoughts about 45 deg vs 90 deg, but have you considered a face mill that uses round inserts? The surface finish from mine is great.



Ditto


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## KC2IXE (Mar 8, 2012)

I actually have a small, single insert mill from

http://www.rotarytech.com/

I have one of their small fly cutter, If I told you how many YEARS I've run that cutter, and the small little mill I started with, I think you'd be shocked (I got it when they were running an itro sale, oh, mumble mumble years ago (say about 15)

I see they are up to $75 - I think the special deal they ran (I think it was when I was on Compuserve - tells you how long ago it was), it was a "email us and well send it to you for $20", or some silly number like that


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## precisionworks (Mar 8, 2012)

> do you have a surface plate/granite slab etc for checking the alignment of the inserts?


I've replaced an insert or two over the years and never saw any machinist check inserts for equal height or alignment. The pocket of a decent quality face mill will completely enclose the insert & the screw or clamp will assure that alignment is the same every time.


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## gt40 (Mar 9, 2012)

Thanks everyone for the info. I got a Glacern 2" R8-FM45-200 ordered.


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## precisionworks (Mar 9, 2012)

gt40 said:


> Thanks everyone for the info. I got a Glacern 2" R8-FM45-200 ordered.


Good choice 

The high shear face mill takes very little power compared to a tool that has the insert in a less positive (or neutral) inclination. Really quiet as well. There is one disadvantage - the 45° side wall may not work in every situation. 





That's the Glacern FM90A. Every manufacturer makes their own variation of this design. These are 90° tools with neutral or slightly positive rake that use AP** inserts. At 3" diameter this one is a bit large for a R8 mill but gives you an idea what others look like: from eBay listing.


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## gt40 (Mar 9, 2012)

precisionworks said:


> Good choice
> 
> The high shear face mill takes very little power compared to a tool that has the insert in a less positive (or neutral) inclination. Really quiet as well. There is one disadvantage - the 45° side wall may not work in every situation.
> 
> ...



I almost bought that exact one! I plan to add it down the line.

On another note, received the glacern face mill today and am very happy about the build quality. I am still waiting for the ebay inserts I ordered, can't wait to try it out. I ended up with the 2.5" one by mistake. I hope it will be fine with the 3hp motor on the mill. Here is a pic of the actual face mill I received:


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## precisionworks (Mar 10, 2012)

> I ended up with the 2.5" one by mistake. I hope it will be fine with the 3hp motor on the mill.


As long as the size is under 3" it should work well. The limiting factor is not motor hp but rather it is the small physical contact area of the R8 taper. When Bridgeport invented the R8 taper they never envisioned higher horsepower motors & large material removal rates. Every machine that has the R8 taper has this limitation - whether it weighs 1500kg or 300kg. Face mills over 3" (76.2mm) should be run in a minimum 30 taper machine & 40 taper is better yet. Huge face mills run best on a 50 taper machine that weighs 10,000kg or more. 

If you take too deep a cut or feed too quickly your machine will tell you that it isn't happy :devil:


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## themayor (Mar 10, 2012)

i was looking to get one of the Glacern face mils too only thing holding me back is getting the inserts for steel and alum 169 for 10 for each n hardly any on ebay. Wish they would break them down in give you like 5 of each being about to use all the sides they should last along time


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## precisionworks (Mar 10, 2012)

themayor said:


> i was looking to get one of the Glacern face mils too only thing holding me back is getting the inserts for steel and alum 169 for 10 for each n hardly any on ebay. Wish they would break them down in give you like 5 of each being about to use all the sides they should last along time



$60/10 http://www.ebay.com/itm/10pcs-Korlo...0?pt=BI_Tool_Work_Holding&hash=item415fb313ca

$4 each (free shipping) http://www.ebay.com/itm/New-SEHW-43A6-KT313-KENNAMETAL-CARBIDE-INSERT-/370474518570?pt=LH_DefaultDomain_0&hash=item564200882a


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## themayor (Mar 10, 2012)

thanks wish the last one had more than one for sale guess ill pic up the other one, How do you know what inserts are for what material?


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## precisionworks (Mar 11, 2012)

themayor said:


> thanks wish the last one had more than one for sale



Those went fast, someone else must have found them.



> guess ill pic up the other one, How do you know what inserts are for what material?



NCM325 is a CVD coating. Image shows ISO materials PMKNSH:

P=steel
M=stainless
K=cast iron
N=nonferrous
S=hi temp alloys
H=hardened materials

Mostly called a GP (general purpose) insert.


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## unterhausen (Mar 12, 2012)

I was looking at the Glacern face mills, I didn't see where it said what the shank interface was. There are only a couple of face mill holder types, but I wouldn't want to get the wrong one. I have a NMTB 30 taper mill, so that's a bit of a concern for me.


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## precisionworks (Mar 12, 2012)

unterhausen said:


> I was looking at the Glacern face mills, I didn't see where it said what the shank interface was. There are only a couple of face mill holder types, but I wouldn't want to get the wrong one. I have a NMTB 30 taper mill, so that's a bit of a concern for me.


The integral shank tools are made as one piece with r8 arbor. This is what you can't use:







What you want is the same head in a "shell mill" design that accepts any arbor available - straight shank, CAT, NMTB, etc.






All the big suppliers sell the shell mill arbors. 






(from McMasterCarr.com)


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## unterhausen (Mar 12, 2012)

the shell mills are on the same page as the fixed arbor, but they only list compatibility with their own arbors. Guess I have to check to see what the arbors are compatible with. I have a shell mill holder, been a while since I checked the specs on it though

on edit: looked up the arbors, looks like up to a 3" shell mill has a 1" arbor hole diameter


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## precisionworks (Mar 13, 2012)

unterhausen said:


> the shell mills are on the same page as the fixed arbor, but they only list compatibility with their own arbors. Guess I have to check to see what the arbors are compatible with. I have a shell mill holder, been a while since I checked the specs on it though
> 
> on edit: looked up the arbors, looks like up to a 3" shell mill has a 1" arbor hole diameter


Shell mills & shell mill arbors have been around for decades, predating the industrial use of cemented carbides (1960-ish). I'll go waaay out on a limb and say that any shell mill can be run on any arbor of the correct size. It's interesting that Glacern lists only R8 & CAT40 arbors, but that covers everything Bridgeport & also covers the most popular V-flange in use today. 

30 taper shell mill arbors are available in 3/4", 1" & 1 1/4" as well as metric diameters (not interchangeable). NMTB30 is more popular on the other side of the ocean & you can often find some on eBay like these eight listings.


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## unterhausen (Mar 13, 2012)

turns out I have a 1" arbor, so I'm good to go


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