[keen]

I find this work challenging. If the settings and cutter are not right the cutter will soon break down and self destruct!

The pics below show a 100mm bore cut in 56mm thick 4150 H/T steel. I cut through 28mm from each side. I have found that a small negative top rake needs to be lapped on the cutting edges for it to last the distance. Without this 'Eating' its own swarf and the chatter (difficult to entirely avoid especially on a light NC mill) will cause a sharp edge to break down quickly in tough steel.

[dertsap]

you'e be best off using a coated variable flute end mill with a slightly radiused corner .03" or so

[Geof]

It is called "honing", and yes it does prolong tool life.

What you can also do is rig up a powerful airblast to blow chips clear to avoid recutting.

[keen]

you'e be best off using a coated variable flute end mill with a slightly radiused corner .03" or so

I should have mentioned I dont use new cutters for this work - I diamond grind by hand about a 15 deg chamfer on a blunt carb cutter. Also makes the neg top rake lapping easier also.

[keen]

It is called "honing", and yes it does prolong tool life.

What you can also do is rig up a powerful airblast to blow chips clear to avoid recutting.

Hell Geof - if I used an air blast on an open machine I would have chips for miles!

[dertsap]

I should have mentioned I dont use new cutters for this work - I diamond grind by hand about a 15 deg chamfer on a blunt carb cutter. Also makes the neg top rake lapping easier also.

if your doing it for money and production then I suggest getting the right tool for the job , it will pay for itself , if its for hobby then what ever works
the collet probably isn't helping with the chatter , if you have a solid holder then that would probably help

[keen]

if your doing it for money and production then I suggest getting the right tool for the job , it will pay for itself , if its for hobby then what ever works
the collet probably isn't helping with the chatter , if you have a solid holder then that would probably help

dertsap are you using a tormach?

[dertsap]

no

[keen]

Thought so, you see the right tool for the job is relative to the potential of the machine you are using it on. My point is a light mill can easily wreck an expensive cutter. I do take your point about mounting the cutter more directly though - I am sure it would help with the chatter issue. I will buy a R8 to 10mm and 12 mm and do that next time.

[Art Pentz]

Hi Keen;

I recommend using one of these (in the appropriate size):


http://www.maritool.com/Cutting-Tool...duct_info.html


These vari-flute endmills are normally run dry and work great on my Tormach.

The TIALN coating seems to make a big difference in steel (which is primarily what I use).

I tried other types of endmill (some a LOT more expensive) and found that these minimize chatter and last longer than any others that I have tried.

Maritool is a very good source for high performance/high value tooling.

No afiliation etc....

[Andre' B]

I would be tempted to try a cutter like this.
http://www.colecarbide.com/MillstarCatalog/HFI4-EM.jpg
Does all the cutting on the end with the side flutes tapered back.

But the Tormach may not feed fast enough to make effective use of it.

[philbur]

The cheapest way to remove material with regard to tool cost is to drill it. So drill an appropriate hole pattern and then finish with an end-mill.

Just a thought
Phil

[dertsap]

Thought so, you see the right tool for the job is relative to the potential of the machine . .

I've worked with many applications that were unstable or lacked rigidity so for me It really doesn't matter what type of machine it is , it's a matter of setting it up in a way to use the machine to it's fullest potential , programming tooling and fixturing are the keys to success along with other factors such as chip evacuation . I fully understand the lack of rigidity and power in the small mills and chatter absolutely destroys tooling , the variable mills are designed to reduce or eliminate chatter , they out run regular end mills ten fold at far more aggressive speeds and feeds ,doc , and engagement . they are far more beefy and are less prone to shock that standard end mills
to give an example of how these types of tools can run , I decided to test toroidal toolpaths on mild steel with a CGS variable that I had on the shelf http://cnctoybox.com/shop/category_7...=cid%3D%26 , two things that I wanted to prove was that those types of toolpaths don't need a lot of torque and that a guy can run steel on a wood router if it is done right even though everyone believed it couldn't be done , so I turned to my router table which I designed for wood or light aluminum cuts which is by no means anywhere near as rigid as a Tormach mill , the wood router spins at 25000 rpm so I started off slow then bumped it up to 120ipm , the cut was good and after a number of passes the tool is in the same state as it was when I pulled it out of the tube

tooling and setup is what will make or break a guy
[ame="http://www.youtube.com/watch?v=s1ftb_cA4nE"]YouTube - cutting steel[/ame]

[keen]

Hi Keen;

I recommend using one of these (in the appropriate size):


http://www.maritool.com/Cutting-Tool...duct_info.html


These vari-flute endmills are normally run dry and work great on my Tormach.

The TIALN coating seems to make a big difference in steel (which is primarily what I use).

I tried other types of endmill (some a LOT more expensive) and found that these minimize chatter and last longer than any others that I have tried.

Maritool is a very good source for high performance/high value tooling.

No afiliation etc....

Thanks - but US$37 ! I could justify them for clear milling - but deep slotting is hard on cutters. Have you done deep slotting with them? maybe I am wrong but to date for this type of work I get a bundle of used carb end mills from a CNC shop for a dozen beers and sharpen a bevel on the ends - the rest is usually still sharp.

[keen]

I would be tempted to try a cutter like this.
http://www.colecarbide.com/MillstarCatalog/HFI4-EM.jpg
Does all the cutting on the end with the side flutes tapered back.

But the Tormach may not feed fast enough to make effective use of it.

Thanks - I tend to agree with you. Its only the end that gets blunt anyway. with deep slots the rest just eats chips and gets in the way. But those cutters look pricey....

[keen]

The cheapest way to remove material with regard to tool cost is to drill it. So drill an appropriate hole pattern and then finish with an end-mill.

Just a thought
Phil

Hi Phil - I think you are right, but you would need to drill pilot holes on at least every second hole so that the break through drills stayed on track. I must try it some time.

[keen]

I've worked with many applications that were unstable or lacked rigidity so for me It really doesn't matter what type of machine it is , it's a matter of setting it up in a way to use the machine to it's fullest potential , programming tooling and fixturing are the keys to success along with other factors such as chip evacuation . I fully understand the lack of rigidity and power in the small mills and chatter absolutely destroys tooling , the variable mills are designed to reduce or eliminate chatter , they out run regular end mills ten fold at far more aggressive speeds and feeds ,doc , and engagement . they are far more beefy and are less prone to shock that standard end mills
to give an example of how these types of tools can run , I decided to test toroidal toolpaths on mild steel with a CGS variable that I had on the shelf http://cnctoybox.com/shop/category_7...aram=cid%3D%26 , two things that I wanted to prove was that those types of toolpaths don't need a lot of torque and that a guy can run steel on a wood router if it is done right even though everyone believed it couldn't be done , so I turned to my router table which I designed for wood or light aluminum cuts which is by no means anywhere near as rigid as a Tormach mill , the wood router spins at 25000 rpm so I started off slow then bumped it up to 120ipm , the cut was good and after a number of passes the tool is in the same state as it was when I pulled it out of the tube

tooling and setup is what will make or break a guy
YouTube - cutting steel

Very interesting dertsap - good to see you are not scared of challenges! building on that demo, deep slotting work on a light mill may be best with shallow cuts, high feed rates....but then...somehow you would need to get all the chips out?.....

[Art Pentz]

Hi Keen;

My limited experience indicates that there are huge differences in the performance of endmills that "look" the same visually.

The better quality variable flute geometry endmills really can make a difference in your tool life and finish quality - especially on a Tormach.

You owe it to yourself to compare a high quality vari-flute endmill to what you are now using - the difference may surprise you.

In any event, you MUST get the chips out of the slot as fast as they are made - re-cutting chips is death to any carbide endmill.

I use a microdrop lubricator (Unist) and the air blast can be used to remove the chips from deep holes.

As you mentioned, you have to get creative to shield the surrounding area from the flying chips.

If tou run TIALN endmills dry, the chips will be HOT - incandesent - this is OK if your feed rate is high enough so that the chips are removing the heat.

This can be very disconcerting the first time you use TIALN endmills dry in steel.

Water based coolant can actually fracture the carbide cutting edges due to thermal stresses - I find that running TIALN coated endmills dry works best for tool life.

Besides, you get that nice "fireworks" show from the glowing chips if you are feeding properly.

If you use a vacuum hose to suck up the chips, be aware that the hot chips can melt plastic, burn skin/clothes and present a potential fire hazard.

Good luck w/ your experimentation.

Art Pentz

[keen]

Thanks Art - I agree with you in theory, but in practice how do you get chips out of deep circular slots easily and efficiently on a one off part. I doubt it is worth the time setting up multiple air blasts and chip collecting sheilds etc for one part. My point is why not hand sharpen a blunt freebee cutter, lap negative top rake so it does not break down, live with a bit if chip munching and get the job done. I agree with the points above for multiple parts on an enclosed machine. "Horses for courses"

[dertsap]

good to see you are not scared of challenges! .

not really a challenge but more for fun and curiosity , most of my challenges come from my day job so its nice just to play sometimes

...somehow you would need to get all the chips out?.....

as Geof pointed out your best bet is air blast , you can setup some sort of guard setup to keep the chips somewhat under control ( drop sheet , build a box etc ) , without it then your going to be recutting chips and on hard material its never pretty