[SCzEngrgGroup]

i think youve done your math wrong on the feed rates. the second is .004" feed per tooth, and it is very agressive. agressive seems to be the recomendation for hard milling. the same bit in 1018 would need a different strategy.

the first has an effective feed per tooth near .0003" due to the shallow axial cut.

Yeah, I somehow slipped a decimal place on the chiploads. Still quite aggressive though. What is your tool life like at those rates?

How do you calculate effective feed per tooth for shallow cuts? I've never seen that explained. I assume that's part of the magic behind HSM?

Regards,
Ray L.

[ihavenofish]

Yeah, I somehow slipped a decimal place on the chiploads. Still quite aggressive though. What is your tool life like at those rates?

How do you calculate effective feed per tooth for shallow cuts? I've never seen that explained. I assume that's part of the magic behind HSM?

Regards,
Ray L.

shallow widths and depths are key to hard milling and high speed milling in general it seems. but you need to maintain a certain level, or youll have problems. if you dont have 5000rpm+, your probably not going to have much luck with hard steel.

tool life i dont really have a personal comment on... havent worn out a tool yet as i dont do alot of machining in hard steel right now. i did kill the variable flute bit outright though in some soft o-1 jogging into the piece by accident. before that it was doing great! haha. supposedly tool life vs removal rate isnt much if any worse than going slow - plus you save on coolant.

ive been using the kenametal calculator, which will give you optimized feed rates based on radial depth. the sandvik one does the same, but its meant for their own indexable tooling only so the actual speed recomendations might not apply.

geof on this forum has a video of his haas cutting 1018 at ~600sfm with a 1/2" carbide end mil about 3/4" deep. it was a trocoidal pass with i think .025" radial depth.

there was an article on mmsonline with some starting point guidelines for hard materials.
http://www.mmsonline.com/articles/ha...e-numbers.aspx

basically between hrc 45 and 60 it recomends 400 to 600sfm as a starting reference which seems to be near where i landed.

frank at maritool recomended a slower sfm(200) but even more agressive feed for the tool i was using to improve tool life though he was specifically talking about 58hrc 4340HT which may behave differently than the vise steel or tool steels.

heres a video of the bit i was using - 4140 steel, 450sfm, .45" depth, about 50% stepover, 55ipm. he states the tool life as well in the comments.
[ame="http://www.youtube.com/watch?v=cbdCo2uhpS8&feature=channel"]YouTube - Double Ended Variable Flute[/ame]

the strategy with the harder materials is to simply go shallower width or height, but faster.

[SCzEngrgGroup]

shallow widths and depths are key to hard milling and high speed milling in general it seems. but you need to maintain a certain level, or youll have problems. if you dont have 5000rpm+, your probably not going to have much luck with hard steel.

tool life i dont really have a personal comment on... havent worn out a tool yet as i dont do alot of machining in hard steel right now. i did kill the variable flute bit outright though in some soft o-1 jogging into the piece by accident. before that it was doing great! haha. supposedly tool life vs removal rate isnt much if any worse than going slow - plus you save on coolant.

ive been using the kenametal calculator, which will give you optimized feed rates based on radial depth. the sandvik one does the same, but its meant for their own indexable tooling only so the actual speed recomendations might not apply.

geof on this forum has a video of his haas cutting 1018 at ~600sfm with a 1/2" carbide end mil about 3/4" deep. it was a trocoidal pass with i think .025" radial depth.

there was an article on mmsonline with some starting point guidelines for hard materials.
http://www.mmsonline.com/articles/ha...e-numbers.aspx

basically between hrc 45 and 60 it recomends 400 to 600sfm as a starting reference which seems to be near where i landed.

frank at maritool recomended a slower sfm(200) but even more agressive feed for the tool i was using to improve tool life though he was specifically talking about 58hrc 4340HT which may behave differently than the vise steel or tool steels.

heres a video of the bit i was using - 4140 steel, 450sfm, .45" depth, about 50% stepover, 55ipm. he states the tool life as well in the comments.
YouTube - Double Ended Variable Flute

the strategy with the harder materials is to simply go shallower width or height, but faster.

That is fascinating! I had thought that "HSM" meant VERY high spindle speeds, like 25K and up. It's amazing seeing a more-or-less regular carbide tool doing those kinds of cuts in steel, dry! I'll have to try that sometime.

Regards,
Ray L.

[ihavenofish]

That is fascinating! I had thought that "HSM" meant VERY high spindle speeds, like 25K and up.

well, it does when you are dealing with smaller tools or aluminium.

the nice thing for hobby people is that the strategy makes for lighter loads, which means even little machines can do well at it. you need absolutely no play in the system though for best results. on my machine because i have play in the Z axis, i need to load the cutter so it deflects instead of chatters. too slow and its just broken tools.

[Enraged]

novakon's version is a 6k spindle now. machine tools warehouse is selling the sieg versions in canada. so, not to cut off LMS, but theres no real reason to buy from the US in the case of an X3 variant turnkey cnc since there are 3 canadian suppliers.

just looking at their site, novakons NM-135 has a work envelope of 13.75" in X, 8" in Y, and 11" in Z, along with a 1.5hp 6000rpm spindle. seems like a much better deal than the LMS 3503 that only has 11.2" in X, 4.7" in Y, and 10.6" in Z and a 1.3hp 5000rpm spindle. all for the same price... time to start saving my pennies I think.

[SCzEngrgGroup]

well, it does when you are dealing with smaller tools or aluminium.

the nice thing for hobby people is that the strategy makes for lighter loads, which means even little machines can do well at it. you need absolutely no play in the system though for best results. on my machine because i have play in the Z axis, i need to load the cutter so it deflects instead of chatters. too slow and its just broken tools.

What I'd always read indicated HSM required spindle speeds on the order of 10X what was used in normal machining. I normally run about 6K RPM in aluminum with carbide tools, which would translate to perhaps 2K RPM in steel. So, you're only running about 2-3X that. I would not have thought that fast enough. I do have 8200RPM on tap, so I'll have to take out one of my fresh carbide tools and have a go at some steel, and see what kind of damage I can do.

Regards,
Ray L.

[ihavenofish]

What I'd always read indicated HSM required spindle speeds on the order of 10X what was used in normal machining. I normally run about 6K RPM in aluminum with carbide tools, which would translate to perhaps 2K RPM in steel. So, you're only running about 2-3X that. I would not have thought that fast enough. I do have 8200RPM on tap, so I'll have to take out one of my fresh carbide tools and have a go at some steel, and see what kind of damage I can do.

Regards,
Ray L.

make sure you use a tialn coated bit.

[ihavenofish]

just looking at their site, novakons NM-135 has a work envelope of 13.75" in X, 8" in Y, and 11" in Z, along with a 1.5hp 6000rpm spindle. seems like a much better deal than the LMS 3503 that only has 11.2" in X, 4.7" in Y, and 10.6" in Z and a 1.3hp 5000rpm spindle. all for the same price... time to start saving my pennies I think.

also note the nm-135 comes with a full mach license as well as bobcam and the stand is included.

[pete from TN]

All of the steel cutting I have done on my RF thus far has been with the factory gearbox and cutting around 1500 rpm. At 5k you would need some serious feed rates and lots of rigidity to make it work. I have never had a very small mill like the Taig but it may very well react differently than a larger mill would but the feeds and speeds are the feeds and speeds generally despite the machine. The only thing that really makes a difference in those is available HP from what I have seen. I normally cut steel at about 1/2 the rpm of aluminum right or wrong that is what seems to work for me....

Of course your mileage may vary... peace

[pobanion]

Hi 2_many_hobbies...

Sorry about the web site being down.. I will be leaving my current incompetent hosting company (Internic.ca) for another. My site has been down for 2 days now and they just keep telling me their hosting dept is working on it.... Up until 5:00pm that is, then it is time for them all to go home. But not to worry they will fix it tomorrow... This seems to happen on a regular basis.

Anyway... once the site is working again, look for the new pricing on my super sized RF45's and the Sieg machines.

www.MachineToolsWarehouse.com

Sorry about the mess... My hosting company was attempting some kind of upgrade. The site is back up again.

www.MachineToolsWarehouse.com

[2_many_hobbies]

Sorry about the mess... My hosting company was attempting some kind of upgrade. The site is back up again.

The site is quicker than it was too so thats nice, I use servage.net for a whopping $6/month and in the 4 years I have never seen downtime. If you wanted a cheep backup or a place to store media as the site expands check it out.

[pete from TN]

Just wondering about that super sized RF, is it the same machine as the IH is or does it just look like it? I have an RF45 Lathemaster mill and a knee mill. Now that my rf45 is cnc I see the beauty and would not mind getting another one to cnc. IF I did I would not do the knee mill but would rather do a larger bedmill such as the one you are talking about. How much would it be to ship one to Tennessee 37803 just out of curiosity? If you have any sway with the manufacturers, maybe try to talk them into a large bedmill like that only with a belt drive and vfd instead of the gear head. That would be a sure winner for cnc or not... just a thought...peace

[SlowRiderr]

ive cut 1018 steel with uncoated m42 cobalt end mills on my tiny little kx1. ive also cut the same steel, along with o-1 and hrc55+ vise steel with maritool variable flute tialn bits. i tried uncoated carbide on 1018 and it worked but poorly.

the trick for me seemed to be high-ish surface speed, shallow depths and agressive feeds. 325sfm with the cobalt, and 650sfm on the variable flutes in hardened steel. 100-15sfm in the o-1. no more than 10% diametre in depth of cut (axial or radial). slotting full width was generally not a good idea, though the variable flute with a corner radius would do it to a point. smaller bits were more efficient on my machine because of rigidity.

so, for example, in 1018 using a 1/4" 3 flute cobalt bit:
5000rpm
.25" depth
.025" width
60ipm
mist coolant

in hrc55 vise steel with a 1/2" 4 flute tialn carbide variable flute:
5000rpm
.025" depth
.375" width
100ipm (max for the machine)
NO coolant

the last one seems counter intuitive, but works amazingly well. keep in mind my machine isnt very big or rigid, and has a mere 0.6hp.

in short, nearly any of the machines listed here "can" cut steel. you just need to optimise your cutting strategy to suit. im leaning to getting a weiss wmd25lv at some point.

Do you know how to calculate speeds and feeds?

RPM = (4 * Cutting Speed) / Diameter

Feed = RPM * # of Flutes * Chipload

Cutting speeds: Alum 200, CRS 100, Tool Steel 50
Chiploads: Tool Steel .001, CRS .003, Alum .005

[ihavenofish]

Do you know how to calculate speeds and feeds?

RPM = (4 * Cutting Speed) / Diameter

Feed = RPM * # of Flutes * Chipload

Cutting speeds: Alum 200, CRS 100, Tool Steel 50
Chiploads: Tool Steel .001, CRS .003, Alum .005

confused, was that a critique of my cutting data, or nostalgia about using bridgeports in the 70's?

[SCzEngrgGroup]

Do you know how to calculate speeds and feeds?

RPM = (4 * Cutting Speed) / Diameter

Feed = RPM * # of Flutes * Chipload

Cutting speeds: Alum 200, CRS 100, Tool Steel 50
Chiploads: Tool Steel .001, CRS .003, Alum .005

Those numbers are pretty far off the norm. Typical SFPM for HSS in aluminum ranges from 300-600, not 200. Double, or triple, those for carbide. With the exception of very small tools (under 1/8") chipload varies linarly with tool diameter, with 0.002" being a good average value for a 1/2" tool (so 0.001" for 1/4", 0.0005" for 1/8"). You try cutting 0.005" with a 1/4" tool, and unless it's a very shallow cut, you'll end up with a broken tool. And with a shallow cut, your tool life will be significantly reduced. With the above numbers, your tools will last almost forever.

Regards,
Ray L.

[SlowRiderr]

Those numbers are pretty far off the norm. Typical SFPM for HSS in aluminum ranges from 300-600, not 200. Double, or triple, those for carbide. With the exception of very small tools (under 1/8") chipload varies linarly with tool diameter, with 0.002" being a good average value for a 1/2" tool (so 0.001" for 1/4", 0.0005" for 1/8"). You try cutting 0.005" with a 1/4" tool, and unless it's a very shallow cut, you'll end up with a broken tool. And with a shallow cut, your tool life will be significantly reduced. With the above numbers, your tools will last almost forever.

Regards,
Ray L.

You realize the norm for around here is generally people who have no official education in machining and have learned by reading what other people say. If using Carbide you multiply RPM * 2.5

Obviously this rule doesn't apply to all cutters ever made, especially small diameter cutters. If you look at any educational info (not forum posts or what other machinists have said) about machine tool cutting you will see it lines up with what I posted.

[SlowRiderr]

confused, was that a critique of my cutting data, or nostalgia about using bridgeports in the 70's?

It doesn't matter what year your machine is from, physics don't change.

[SCzEngrgGroup]

You realize the norm for around here is generally people who have no official education in machining and have learned by reading what other people say. If using Carbide you multiply RPM * 2.5

Obviously this rule doesn't apply to all cutters ever made, especially small diameter cutters. If you look at any educational info (not forum posts or what other machinists have said) about machine tool cutting you will see it lines up with what I posted.

Well, I can't account for un-named educational info. I do know I've never seen a tool manufacturer recommend numbers in those ranges. I've never seen any tool manufacturer recommend SFPM for aluminum at less than 300 SFPM, and most are 400-600 for HSS, and much higher for coated tools, and carbide tools. Same with chipload. I've never seen a HSS tool for which a chipload of 0.005" was recommended. And given that bearly everyone here is running on a small machine, *not* including the disclaimer about small tools, which nearly everyone here will use frequently, will lead them to broken tools and frustration.

Below is a post I've made a few times that lays out how anyone can come up with the optimum settings for *their* machine, as every machine is different. I've boiled this down to a spreadsheet and set of software tools that generate very nearly optimum settings for any tool, any material, and gives excellent results. It's always baffled me that this information is rarely presented all in one place, making the whole process seem much more complicated than it really is. But, the thing to remember is, every machine is different. What works for one, won't necessarily work for another, so it's important to learn to "read" the cut, and know what to change to improve it. This comes only with practice and experience - there is no other way. I spend countless hours just doing test cuts to come up with the tools I developed for generating the numbers for my machine. But, in the end, it was well worth it.

RPM is determined by tool diameter, and material, by calculating SFPM - Surface Feet Per Minute as follows:

SFPM = (PI * ToolDiameter * RPM) / 12 or,

RPM = (SFPM * 12) / (PI * ToolDiameter)

This is usually rounded to:

RPM = SFPM * 4 / ToolDiameter

SFPM is a function of the tool material and the work material. For mild steel being cut with HSS cutters, SFPM should be around 80. For aluminum, 400 SFPM is a good average. If using carbide, double or triple those numbers. So, if you're cutting mild steel with a 1/2" HSS endmill:

RPM = (80 * 4) / 0.5 = 320 / 0.5 = 640 RPM

Feed rate is a function of RPM, the number of flutes on the tool, and the "chip load", which is the nominal thickness of the chip each tooth carves out:

FEED(in IPM) = RPM * #Flutes * ChipLoad

Chipload is a function cutter diameter, and for roughing cuts ranges from perhaps 0.0004" for very small endmills (1/16") to perhaps 0.004-0.006" for large ones (1"), and varies linearly for sizes in between. So, for a 1/2" 4-flute endmill, assume a 0.002" chipload, and you get:

FEED = 640 * 4 * 0.002 = 5.1 IPM

Depth of cut should be as much as you can get away with, which will be limited by spindle power, machine rigidity, and coolant used.

Now, you're not likely to reach this numbers on a small mill, due to the limited spindle power, limited rigidity, and inadequate cooling. So, start by setting the calculated RPM, pick what you feel is reasonably modest depth of cut, and start by feeding at perhaps half the calculated rate. Increase feed rate until finish quality starts to degrade. When you reach that point, back off on the feed rate perhaps 10%. Now increase depth of cut until the machine starts shaking, or the spindle motor starts laboring, then back off a bit.

There are no canned numbers, as every job is different, and you have to learn how to "read" the machine. Some rules of thumb:

Keep chip load as high as possible. If you find you have to reduce feed rate well below the calculated value, then reduce the RPM to keep the calculated and actual feed rates reasonably close. Running high RPM with low chip load will cook tools faster than anything.

USE COOLANT!! You will never come anywhere even close to the calculated numbers without coolant. A mist system will work wonders, with very little mess.

Here are some typical numbers I use on my knee mill, running mist coolant:

1/2" 4-flute HSS endmill cutting 1018 steel: 700 RPM, 5 IPM, 1/2" DOC
1/2" 2-flute HSS endmill cutting 6061 aluminum: 3100 RPM, 12 IPM, 1/2" DOC

Regards,
Ray L.

[ihavenofish]

You realize the norm for around here is generally people who have no official education in machining and have learned by reading what other people say. If using Carbide you multiply RPM * 2.5

Obviously this rule doesn't apply to all cutters ever made, especially small diameter cutters. If you look at any educational info (not forum posts or what other machinists have said) about machine tool cutting you will see it lines up with what I posted.

the norm for me is to go by what the tool maker suggests, which is why i specifically cited frank mari - the tool maker - with his recomendations and video milling alloy steels and hardened steel. i also posted the MMS article on high speed machining where i derived alot of my numbers originally, not to mention geoff on this board whos posted some impressive videos.

ive also USED the feeds i suggested on my tiny machine with sucess.

if you think what you posted is "the norm" for modern tooling and machinery, you shouldnt visit sandviks website. they have recomendations for surface speeds with certain tools in aluminium of 5000-9000sfm!

the laws of physics havent changed... perhaps your knowledge of them should though. its fascinating stuff.



and again, this is all in the context of what the poster was asking here, which is "what bechtop will cut steel", and my example states "pretty much all of them" with a little forethought. it doesnt mean people should up and go make a mould in d2 using these settings. they need to test the ultimate abilities of their machine, tools and programming skills on their own.

[escott76]

It doesn't matter what year your machine is from, physics don't change.

Boy, I'm guessing that whole hall at Eastec was defying physics then. Check some more modern texts for some updated numbers.