Face milling with a small mill.

[Ken from ontario]

Well that's all I needed to know, ,so they need low rpm and a lot of torque , didn't know that ,they do remind me of annular cutters in many ways.
Again.thank you Bob Korves.

 

[Bob Korves]

Well that's all I needed to know, ,so they need low rpm and a lot of torque , didn't know that ,they do remind me of annular cutters in many ways.
Again.thank you Bob Korves.

Actually, thinking about it more, and assuming 90 SFPM for mild steel, I get a speed of 360 rpm for a 1" HSS end mill. So that is doable. What I must have been thinking about is the 1-1/4 and 1-1/2" cutters I also have, also with no plans for using them. The 1" two flute could work, and it would take no more power than a 2 insert insertable end mill, probably less, at least for cutting on the ends. You could try it, but those are expensive cutters and are also expensive to sharpen, and a big chip will turn it mostly into scrap metal, though they can be reground if you can find somebody to do it at a decent price. I think above about 3/4" it is time to look at insertable end mills. A three or more flute end mill of 1" would also take a considerable amount of power to get it to make cuts having the correct chip load. It it hard to hold some of that tooling in a collet without it coming loose and/or sucking into the work. Adding a Weldon style end mill holder would probably take away all the headroom on your mill and more. Thinking about that on a mini mill, which I have never personally used, just makes me shake my head sideways...

 

[Ken from ontario]

Actually Bob the 2 flute that you say might work is not that expensive ,it's only $32 CDN dollars which is around $24 USD, the 6 flute is about $40 USD, so price wise they are average but I'm not sure of their quality.

 

[Bob Korves]

Actually Bob the 2 flute that you say might work is not that expensive ,it's only $32 CDN dollars which is around $24 USD, the 6 flute is about $40 USD, so price wise they are average but I'm not sure of their quality.

That is cheap, perhaps too cheap... or perhaps a real bargain!

 

[mikey]

A three or more flute end mill of 1" would also take a considerable amount of power to get it to make cuts having the correct chip load.

I agree with Bob, Ken. If you lack the rigidity and power to take a cut with a decent chipload then there will be rubbing on the flutes of the cutter and that big end mill will get dull in a very short time. You can vary feed, you can vary speed and you can vary depth of cut but the closer you adhere to the chipload parameters the manufacturer lists for their cutter, the longer the tool will last. I would be hesitant to use a 1" multi-flute end mill on my RF-31 and its a 400# machine with a 1HP Baldor motor on it. I suspect a small bench top machine will not fare well with a cutter like this, regardless of how good a deal it is.

Just my thoughts on this one.

 

[Ken from ontario]

I agree with Bob, Ken. If you lack the rigidity and power to take a cut with a decent chipload then there will be rubbing on the flutes of the cutter and that big end mill will get dull in a very short time. You can vary feed, you can vary speed and you can vary depth of cut but the closer you adhere to the chipload parameters the manufacturer lists for their cutter, the longer the tool will last. I would be hesitant to use a 1" multi-flute end mill on my RF-31 and its a 400# machine with a 1HP Baldor motor on it. I suspect a small bench top machine will not fare well with a cutter like this, regardless of how good a deal it is.

Just my thoughts on this one.

What you and Bob are saying makes perfect sense, this has been an eye opening thread for me and probably for a lot of others with smaller milling machines, we either listen to the logic behind what has been said or will soon have a collection of cutting tools in perfect condition because we can't use them.
I already have decided to start my search on smaller bits 3/4" max, I've used that size end mills and I know my machine can take it.
Thanks very much Mike.appreciate sharing your thoughts as always.

 

[Downunder Bob]

For the past 2 days I have been using the search function here on what tools to use for face milling Aluminum and mild steel, especially when the milling machine the tool goes onto, is a mini mill.
I found out a few important points and now I'll bring them up and ask you guys to please correct me in my findings :
1= with a 1/2 HP mill, It is best to use a smaller size indexable face mill.
2= the size of the indexable face mill should not be bigger than 1.5" you may get away with a 2".
3= the best type of inserts for a small mill (which does not have a very ridgid mill head) is, TPG32.
4= the indexable face mill head should have at least 2 inserts but 3 is even easier on the machine, less vibration.
5=If possible,It's best to use a collet than an R8 EM holder , less chance of the tool vibrating .
6= Adjust your feed rate and RPM to get a chatter free operation.
Am I missing any other important point? how about using compressed air for chip evacuation? or maybe using coolant(spray?),I do have the option to use a fly cutter but find it a bit too slow,overall I'm not comfortable using it but regardless of using that option,I still want to learn which indexable face mill is best for my mill. your comments as usual are important to me and very much appreciated.

Ken I think you are suffering under a misconception, with cutters and power. The more cutting points on a cutter the more power you will need. With each different cutting approach the number of cutters actually cutting will vary. If plunge cutting with an end mill all points will be cutting, but when side cutting such as facing a plate only half of the cutting edges will be cutting if you are using the full width of the cutter.

To reduce the power required we typically reduce the DOC and/or feed. eventually getting to the point where the tool is doing more rubbing than cutting. If you want to exceed the 1.5" face mill cutter then use a single point fly cutter, with this cutter you can face pretty much anything that will fit on the table of the machine. Set the dia. of the cutter to be somewhat larger than the piece you want to cut.

You can use HSS or carbide, but if using carbide make sure the grade is ok for intermittent cut. Be careful to reduce the RPM as you increase the dia of the cut. Also remember a sharp HSS cutter will require a lower speed and less power than carbide. HSS tends to be better at very light cuts.

The major limitations of your small machine are power and rigidity, so it will be important to be mindful of the loss of power at the low end of your variable speed motor, and also to balance the cutter to help offset the lack of rigidity. Hope this helps.

 

[Ken from ontario]

Bobshobby, thanks for joining in and for your comment, throughout this long thread we have covered a few of the misconceptions you are talking about already,i.e. 3 point cutter vs 2 point or one, 3 point EMs being the least suitable for a mini mill due to their lack of power and rigidity ,my original post was what I had gathered by reading other threads relating to indexable end mills and their appropriate sizes for smaller /less powerful milling machines but the more seasoned members did put me on the right track but thank you again to reiterate the points for clarity.we are here to learn and I for one appreciate all the help I could get .

 

[darkzero]

Ken, when you are referring to the number of cutting points on a cutter, that is what is known as flutes. But keep in mind the number of flutes on an indexable cutter vs the number of flutes on an endmill is not really the same. For smaller than say .75" or so, you probably won't find an indexable endmill with more than 1 flute/insert. but let's just say that there was. The endmill will probably perform better cause it has a helix where the insert just has a single straight edge for each flute. Also at the end of the endmill, each flute has a longer very positive angle cutting surface than an insert which would just be a tip & dependent of the nose radius.

Not to discourage you but on a smaller size mill, you may just be better off with an endmill & not in such a large dia rather than an indexable endmill. On my larger benchtop mill, the largest endmill I use is 5/8" (but not for hogging). I can take deeper depths of cuts with a smaller dia endmill than I can with any of my indexable tooling. It may require more passes but in the end you still might be removing the large amount of material faster than an indexable. Also keep in mind with an indexable endmill & depending on it's geometry, you get some harsh beating similar to a flycutter so if you don't have a rigid machine, that will limit you as well.

Point is you can't always find an alternative for a good ol endmill. It may be that you just need to find the right type of endmill & I'm not sure if anyone talked about that yet. Try a 4 flute coarse roughing endmill for steel, so much more free cutting than a regular endmill for fast material removal. Or for aluminum try a 3 flute roughing endmill or even a high helix 3 flute. The high helix 3 flute endmills work great in aluminum.

What's interesting is that Stephan Gotteswinter even uses the 3 flute high helix endmills for roughing in steel. He also has an endmill shootout video.

 

[Dabbler]

just to add to darkzero's (which are right on!) comments, Stefan Gotteswinter tends to do very accurate work, and doesn't (usually) use indexable cutters on his mill. He does use brazed on carbides from time to time.