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form_change
04-23-2011, 05:55 AM
I got some second hand tooling the other day at a good price, but I've caused myself a problem. The arbor (Nikken) has a 1" mounting shaft. The face mill came fitted to a straight shaft which I thought I could mount on the arbor, but the hole is 7/8".
I suppose it is possible to grind out the face mill or grind down the shaft but it would have to be done just right or lose concentricity. (Thoughts anyone?)
The other alternative is to buy another face mill. Lots on ebay but they raise more questions so what are the opinions out there, specifically on -

I realise that it is the inserts that do the cutting but are there good and bad brands of face mill (that is, the thing the inserts attach to)?
Some face mills take 6 or more inserts. For HSM purposes, are these really any better than a 4 or 5 insert face mill?
Is there a particular style or shape of insert that people would avoid (or recommend)?


Thanks,
Michael

PixMan
04-23-2011, 09:13 AM
Hello Michael. You do NOT want to alter the bore of a cutter because it's quite likely that you will:

A) lose concentricity of the bore to the insert pockets
B) Ruin your boring tool because most cutters are (at least) case hardened

Check that bore again. Most "inch" cutters have even 1/4" increments of bore size as it relates to cutter diameter. Cutters using shell mill mount configuration start at about 1.5" and go up to perhaps 2.5" with 3/4" bores. Cutters 3" use 1" pilot diameter bores, and over that up to about 6" use 1-1/2" bores. Bigger that that have 2.5" pilot bores, but usually use that for location only and bolt onto a spindle face with a 4" or 7" 4-bolt pattern.

I suspect you may have a 22mm bore on a metric cutter. What type of spindle adaptation does your machine have? Is it R8, NMTB40, CAT40, or ??

There are certainly good or bad face mills out there. Most of the bad ones are clear: Old ones from even well-known makers which are now obsolete and you can't get repair parts. Other bad ones are VERY subjective. You wouldn't pay me to use certain cutters from a certain country of origin, but that's a story for another forum.

Insert density (count, etc.) has nothing to do with HSM or commercial application. It has to do with productivity and available power. If you have a 6" insert mill with 16 inserts (and I do), you simply cannot get even 1/3rd of those inserts taking a nominal .005" feed per tooth load with a 1HP Bridgeport. If you have too many inserts in your cutter, and bury too many of them in the cut at once, you face a choice. You can take a low depth-of-cut and keep feed rate up, or you can lower you feed-per-tooth to use less power. You'll wear out just the tips one way, or the whole edge the other. Lower the cutting speed to avoid wearing out the inserts, but risk chipping them from too low of a cutting speed.

I recommend two types of insert mills, should you deem it truly important to get one. I like 45 lead true face mills using high-positive square inserts for facing. I like APKT/ADMT (etc) style parallelogram shape insert mills for use as shoulder mills. If you can only afford ONE cutter to start with, I'd get the face mill first. I am reluctant to get specific about any recommendations here because of the advertisers. Ping me off list if you want a private conversation about the subject.

I have a small collection of cutters that I use on my dad's old 1HP Bridgeport, successfully I might add. Three of the 4 face mills use ANSI/ISO standard SEHN/SEEN style inserts that are cheap and readily available. The big cutter that uses expensive proprietary inserts is too big for any heavy use on the machine, so I haven't chewed through any inserts yet. It'll take a while anyhow, as they are 8-sided inserts. I also have a few AP-insert style shoulder mills, all taking different proprietary inserts. Be careful with those cutters because even though insert may look similar and have similar numbers, the inserts may not fit interchangeably.

Lead angle face mills:
http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_0988-r.jpg
From left to right is 4" Walter F2280, 3" Widia, 2" Widia and 1.25" Iscar F45.

Shoulder mills (a.k.a. end mills), plus a ball mill, insert drill/mills and little "button" cutter:
http://img.photobucket.com/albums/v466/kenm10759/Dads%20shop/IMG_0740-r.jpg
I could identify them all, but dont have the patience.

The one in the front left side, 2nd from left, which uses TPG inserts is sold. I prefer the others because of the shear angles, top form geometry (a.k.a. chipbreaker) of the inserts and overall better cutting action.