HSS End Mill Sharpening

Greetings all,

I need some advice about end mills in a home/hobby setting.  I have a Grizzly G1006 and I'm using 4 flute HSS end mills.  So far, probably due to my inexperience, they require sharpening after (what seems like) relatively little use in mild steel.  My questions are:

1.  Is there an effective way that I could sharpen the end mills without spending a fortune on surface grinder or other dedicated machine?

2.  Does it make sense to purchase more expensive end mills that would in theory last longer?

1. If using HSS end mills at the appropriate RPM what's a reasonable depth of cut should I use in mild steel?

TIA,

AG

I would say this is true for many materials a lot of hobbyists use such as aluminum, brass, and perhaps even mild steel. If you're into tougher steels like tool steels and alloy steels, cheaper tooling is a waste of time.

Speeds and feeds are ultimately the most important consideration when trying to extend the life of your tooling, as Tristan already stated. I calculate the speed for every tool that goes in the machine. I do a quick mental calculation as cutting speeds aren't written in stone. Going slower is usually good so it's easy to round down anyway.

Feed has a lot to do with experience. How the cut sounds, how it feels, the shape and colour of the chips, etc. Here, slower isn't necessarily better at all and one must play around a bit to get the right feed. An experienced teacher is the best option. Otherwise, there are charts available which list recommended feeds, but you need to do a bit of counting, measuring, and calculating to determine how fast you're feeding by hand.

HTH.

Regards,

Robin

Its exciting to design ur own grinders and jigs ..

R U using collant ? R U Climb milling ? is the work hot rolled steel ?

harder steels cut easier , for machining steel requires the chip to be work hardened before it pops out . The softer the work , the more heat to the cutter before the chip breaks out . 50,000 PSI and 80,000 PSI steel cuts much better than Hot rolled . A great ape bolt cuts turns much easier than a grade 5 ...

I think its easier to learn this stuff NOT from reading this NG . I have a frnd who wants to learn metalwork . But he needs books . I try to be his book . so after lots of talking , i figured i was not a good teacher ... Naturally , since im a doer , i cant possibly translate the stuff in the right cerebral cortex to my L side .

So if you are a right side learner , then get some one to show you , not tell you . Those that need to be told will find metalworking confusing and teaching easy ..... People here who do pick up stuff , have an image allready in their mind , translated from some crappy manual .....

All thats needed is to give them a better image , not a better manual

book or other L side proceedure . It isnt about proceedures , nor text ... its about images . A productive metalworker has images of how stuff fits together and images of what dont work , and this CANT be translated to text nor speech , it would be far too many pages in a book .

Im an EE , and i tried to help others learn Electronics , but English got in the way . Its arbitrary , electronics is NOT . Its a perfect image .

so its our stupid ambigous, English that detours us away from quick effecient communications and understanding , and instead makes us go back to college , thinking theres something wrong or short or lacking in US !! The colleges proffs pocket books like that a lot ....

To be trully helped , here , one needs to learn the "terms" , the doers use . You can help create them , just imagine a problem then create terms that connect ( as in NON-SEQUITAR ) .... That was for all the pHD's ....

I want to structure Engineering English ....like time date . year month DayDate DOW hour min sec .... This is easier to read , than 6/5/6 June 5 ? or May 6 ?

and TPI-20 is threads per inch , but notice i put text ahead of numbers , cause a number , in your mind , must be skipped over then you catch the TPI .... Thats wrong , its Luddite . Im real anti Luddite .

In the future , there will be no jobs for anyone but inventors cause there's an oversupply of factory workers , machine operators . Machinists will exist only in the poorest countries .

Rich countries forced to push all low paid , easy to learn jobs offshore . Thats why HS teach machine shop , its the easiest thing to put in a text book , except maybe basket weaving ...

No more paychecks , unless you can chase "demand" . there will be no demand to build a PC computer , nor a more fuel efficient power plant ( dropping world pop will make crude $1 a barrel ). Carpenters and Electricians will not be seen , sorry no work avail . It will be fleeting , you will make a widget in your factory in Nicaragua and the Italians will copy it and beat your price and you are out of business ( no patents no copyrights , no protection of any kind )

I love it , the free competition ! Thinking up new ideas ....

Im working on a better way to feed wire thru a MIG welder . how about 2 solenoids that charge springs , but i need a way to regulate speed .....

Or a mini cold forge with powered hammers . Im at the place where you do it by hand with work in 2 heavy holders and a 3rd holder/die is on top and U smak it w/ a 16 lb sludge ... force from 3 angles ...

like reducing 1/2" water pipe for a 17mm BallBearing bore . Its lots stronger , stiffer than sked 40 ! HF $5 wheels .... i cut out and use only the min needed to grab the tire and weld a structure to carry 2 6204-2RS BB , but since i dont like text books , i have an image of the other ways to do it , like make a one piece hub and push the BB on to stubs on the hub . Strap down the BB to the frame .... No housing machining ! only hammer an old BB on to accurize the stub , then push the new BB on .

To get the other side to be concentric , U need to twirl hub on an allready fitted BB , in a jig ......

Like cutting trailer axles , U tack weld the new shorter axle , stand it on end and twirl the whole thing on one wheels bearings . Notice where the free end is gyrating if it isn't gyrating , the wheel bearings on the ground are alligned true . Flip it and repeat ... I put 1 degree toe in that way !

Backyard methodology ......how to do somethin w/o a 8 foot long lathe !

Any inventors here ?

Its exciting to design ur own grinders and jigs ..

R U using collant ? R U Climb milling ? is the work hot rolled steel ?

harder steels cut easier , for machining steel requires the chip to be work hardened before it pops out . The softer the work , the more heat to the cutter before the chip breaks out . 50,000 PSI and 80,000 PSI steel cuts much better than Hot rolled . A great ape bolt cuts turns much easier than a grade 5 ...

I think its easier to learn this stuff NOT from reading this NG . I have a frnd who wants to learn metalwork . But he needs books . I try to be his book . so after lots of talking , i figured i was not a good teacher ... Naturally , since im a doer , i cant possibly translate the stuff in the right cerebral cortex to my L side .

So if you are a right side learner , then get some one to show you , not tell you . Those that need to be told will find metalworking confusing and teaching easy ..... People here who do pick up stuff , have an image allready in their mind , translated from some crappy manual .....

All thats needed is to give them a better image , not a better manual

book or other L side proceedure . It isnt about proceedures , nor text ... its about images . A productive metalworker has images of how stuff fits together and images of what dont work , and this CANT be translated to text nor speech , it would be far too many pages in a book .

Im an EE , and i tried to help others learn Electronics , but English got in the way . Its arbitrary , electronics is NOT . Its a perfect image .

so its our stupid ambigous, English that detours us away from quick effecient communications and understanding , and instead makes us go back to college , thinking theres something wrong or short or lacking in US !! The colleges proffs pocket books like that a lot ....

To be trully helped , here , one needs to learn the "terms" , the doers use . You can help create them , just imagine a problem then create terms that connect ( as in NON-SEQUITAR ) .... That was for all the pHD's ....

I want to structure Engineering English ....like time date . year month DayDate DOW hour min sec .... This is easier to read , than 6/5/6 June 5 ? or May 6 ?

and TPI-20 is threads per inch , but notice i put text ahead of numbers , cause a number , in your mind , must be skipped over then you catch the TPI .... Thats wrong , its Luddite . Im real anti Luddite .

In the future , there will be no jobs for anyone but inventors cause there's an oversupply of factory workers , machine operators . Machinists will exist only in the poorest countries .

Rich countries forced to push all low paid , easy to learn jobs offshore . Thats why HS teach machine shop , its the easiest thing to put in a text book , except maybe basket weaving ...

No more paychecks , unless you can chase "demand" . there will be no demand to build a PC computer , nor a more fuel efficient power plant ( dropping world pop will make crude $1 a barrel ). Carpenters and Electricians will not be seen , sorry no work avail . It will be fleeting , you will make a widget in your factory in Nicaragua and the Italians will copy it and beat your price and you are out of business ( no patents no copyrights , no protection of any kind )

I love it , the free competition ! Thinking up new ideas ....

Im working on a better way to feed wire thru a MIG welder . how about 2 solenoids that charge springs , but i need a way to regulate speed .....

Or a mini cold forge with powered hammers . Im at the place where you do it by hand with work in 2 heavy holders and a 3rd holder/die is on top and U smak it w/ a 16 lb sludge ... force from 3 angles ...

like reducing 1/2" water pipe for a 17mm BallBearing bore . Its lots stronger , stiffer than sked 40 ! HF $5 wheels .... i cut out and use only the min needed to grab the tire and weld a structure to carry 2 6204-2RS BB , but since i dont like text books , i have an image of the other ways to do it , like make a one piece hub and push the BB on to stubs on the hub . Strap down the BB to the frame .... No housing machining ! only hammer an old BB on to accurize the stub , then push the new BB on .

To get the other side to be concentric , U need to twirl hub on an allready fitted BB , in a jig ......

Like cutting trailer axles , U tack weld the new shorter axle , stand it on end and twirl the whole thing on one wheels bearings . Notice where the free end is gyrating if it isn't gyrating , the wheel bearings on the ground are alligned true . Flip it and repeat ... I put 1 degree toe in that way !

Backyard methodology ......how to do somethin w/o a 8 foot long lathe !

Any inventors here ?

What is your native language? Randy

Go to a T&C grinder and let them sharpen. Forget it with mills below 10 .. 8 mm diameter. It's not effective.

Not that much in a hobby-environment. Invest in a coolant pump and use it. That will multiply the lifetime.

1/2 the diameter.

Nick

The crappy Chinese end mills that come in blue plastic 2-part tubes with paper labels with the size rubber stamped in blue ink are TOTAL crap! Sorry to be so blunt, but these are the worst junk I've ever seen.

Yes, but it just isn't worth it on small cutters.

Yes. I have moved almost exclusively to M-42 and M-57 Cobalt HSS tools. They often have a slight tan-ish tint to the surfaces where they have been sharpened. They tolerate heat MUCH better than plain HSS. They work better in aluminum, and MUCH better in steel with regards to life of the cutting edge. You need to use a cutting lube, or coolant, especially when doing steel. Threading oil from the hardware store is the minimum, and a coolant made for the materials in question is even better.

I have also started using solid carbide mostly in the 1/8" size. These are easy to break, but take a much heavier cut than HSS without deflection.

Generally, with all end mills, I use 1/2 the diameter for the "plunge" depth, ie. the vertical step down each pass, when "plowing" the full width of the cutter. I can go up to the full diameter step down when milling along the side only. The side depth of cut depends on so many things like tool length, machine and part rigidity, concentration of cutting heat, chip removal, etc. that there is no good rule. But, with a light machine and smaller end mills, I'd never go above 1/4 the tool diameter and about 1 diameter step down at a time. So, for a 1/2" end mill, you might choose .050" depth into the side, and 1/4" step down, and keep the feed up. Depending on the machine, you might do better cutting the side depth to .025" and increasing the feedrate. On a more rigid machine, with rigid tool and workpiece holding, you can increase these depths.

Jon

Oh, I just wanted to add that on sale, the Cobalt HSS tools cost only CENTS more than plain HSS, but the life of the cutting edge seems to be THREE times longer!

Jon

I'm actually using the Grizzly set of HSS end mills.

Could you explain what you meant by your last sentence?

TIA,

AG

If you're cutting a pocket, the chips that you cut fall inside. If they are sucked back into your cutter, you are cutting them again (recutting your chips). HSS cutters are more tolerant of this than carbide, but it can still dull your tools pretty fast. When using an indexable carbide tool, I always use an air blast to blow the chips away.

Its worth it to sharpen ur own mills ...even if they are cheap .. You see them diff , when you have to sharpen them ....

Carbide spins almost 10 times faster , than M42 , or M42+cobalt .

Milling is hard on carbide for the tool enters the work ( interupted cut ),

Turning with C' is uninterupted cut , C' is king here !

Turning is fundamental , but milling is one way , there are others .... .

I see what you mean. Thanks!

AG

Thanks for all the responses. I am looking into cooling now.

AG