I’m just looking for the best stepover and strategy for finishing a large flat surface of hardened s7 tool steel... I’m plan on roughing most of the material away and leaving .002/.003 finish stock to come in and clean everything up with a .078 7 flute Harvey tool end mill with a .005cr I’m wondering what the best step sfm, step over and finish stock would be to achieve a nice surface finish so there is minimal polishing needed... also what would be the best toolpath selection would a traditional pocket toolpath be better or would something like an adaptive or high speed machining strategy be better? My machine is a haas with a 12k spindle.
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Hard milling Mirror finish.
- Thread starter HSM_CHIEF
- Start date
- Replies 29
- Views 8,005
Harvey tools has speed and feed recommendations for all their tools:
Harvey Tool - Hard Milling - Square - For Steels Up to 55Rc
I’d start there.
Harvey Tool - Hard Milling - Square - For Steels Up to 55Rc
I’d start there.
B-Mathews
Hot Rolled
- Joined
- Sep 20, 2013
- Location
- Beaverton Oregon
Dont waste your time calling Harvey that for sure. The last times I have all they could be is readme there speeds and feeds from there own site. Could not answer any technical questions what so ever nor was there anyone they could have called me that might have more knowledge.
I emailed them actually and all they responded with was the feeds and feeds from there website as well... which seem extremely low they are suggesting 50sfm and .00007cpt for that 7flute in 56rc material.
Where can I get a facemill that cuts 56 Rockwell tool steel?? Also this part has a .010x45 bevel that’s sticks up around the entire profile so I would not be able to use the facemill.
onecut
Hot Rolled
- Joined
- Jun 27, 2013
- Location
- england-newcastle upon tyne
You can get a facemill with 45degree approach angle pretty common but I think you may be milling a pocket not facing over the top
Uh...your toolbox? 56 isn't all that hard, a typical coated carbide insert face mill will cut it if you use the right parameters. It won't last like it's cutting 1018 but it'll do it. If you are doing a bunch of facing, they make ceramic inserts for the job, or CBN.
Myself, I'd go carbide feedmill and finish with a bull nose appropriate to your corner rad.
Why use .078 mill?
DMF_TomB
Diamond
- Joined
- Dec 13, 2008
- Location
- Rochester, NY, USA
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a large flat surface of hardened S7 tool steel and you want a mirror finish with a .078" dia end mill. good luck with that
I’m sorry for saying a large surface... it’s a relative term it’s a large surface compared to what I’m used to do I can’t just use a facemill it’s a pocket down in...
DMF_TomB
Diamond
- Joined
- Dec 13, 2008
- Location
- Rochester, NY, USA
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large surface usually talking like many square feet and parts weighing many tons.
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if you can pick the part up without needing a crane its a small part
Attachments
Rstewart
Stainless
- Joined
- Jun 14, 2006
- Location
- Huntsville Alabama
FML 
AARONT
Stainless
- Joined
- Feb 19, 2013
- Location
- Madison, WI
Then how about giving us the details of the pocket that needs a mirror finish. Length, width depth, what size radius is acceptable on the floor, what is the corner radius for the pocket?
Some funny responses in here. I always though "big" was a relative term in the machining world, hence why people speak in terms of lenght-to-diameter ratios's and such. In my world, I'm happy if I can fit a big ol' 2mm hogger on a given part.
Or in other words, you call that a knife?
Do you have a link for this cutter? We have other Harvey stuff here but I didn't know you could get 7-flutes tool this small.
Our shop uses OSG cutters for the smaller stuff, I use their 2mm diamter X 8mm loc w/ .008" corner radius 2-flute all the time.
I would probably leave more like .001"-.0015" roughing stock. For a normal cut I would run it at your full speed 12,000rpm but if you have a large area to cover would probably be best to slow it down to more like ~10,000rpm to make sure the cutter doesn't wear out before you finish a full pass.
Stepover anywhere from 10%-30% of the cutter diameter and with the 2-fluters you can run a fairly high chipload like .001"-.002" because of the lower depth of cut. But with 7-flutes you might not have enough chip clearance in the flutes so might need to experiment here.
As far as surface finish goes, you pretty much get what you get but it should be decent in S7 at 56rc. We run "MQL" oil misted into the air blast which does help surface finish, you might be able to rig something up for this or could try spraying it onto the surface manually.
Or in other words, you call that a knife?
Do you have a link for this cutter? We have other Harvey stuff here but I didn't know you could get 7-flutes tool this small.
Our shop uses OSG cutters for the smaller stuff, I use their 2mm diamter X 8mm loc w/ .008" corner radius 2-flute all the time.
I would probably leave more like .001"-.0015" roughing stock. For a normal cut I would run it at your full speed 12,000rpm but if you have a large area to cover would probably be best to slow it down to more like ~10,000rpm to make sure the cutter doesn't wear out before you finish a full pass.
Stepover anywhere from 10%-30% of the cutter diameter and with the 2-fluters you can run a fairly high chipload like .001"-.002" because of the lower depth of cut. But with 7-flutes you might not have enough chip clearance in the flutes so might need to experiment here.
As far as surface finish goes, you pretty much get what you get but it should be decent in S7 at 56rc. We run "MQL" oil misted into the air blast which does help surface finish, you might be able to rig something up for this or could try spraying it onto the surface manually.
I really appreciate your response! I’m not at work right now but I’ll get you the product number on that end mill tomorrow! Today I cut some s7 with an OSG wsx end mill it was .059dia with 4flutes I ran it at 11,500 rpm and around 22ipm or like .00015fpt and a .002 step over with .002 finish stock it was a pretty big punch surface it was around 2 inches in dia the surface finish came out okay... it was very smooth to the touch but there were still lines in it I’m not sure If this is from the spindle quality of the haas causing some sort of vibration or what? We’re in the market for a high speed machining center like a makino and I’m sure that’ll help the surface finish I checked runout it was under .00015 in a maritool sk16 collet... I’m not sure some people under stand what I mean by like an OD Bevel so I wouldn’t be able to use a facemill haha anyways thanks for the positive response!Some funny responses in here. I always though "big" was a relative term in the machining world, hence why people speak in terms of lenght-to-diameter ratios's and such. In my world, I'm happy if I can fit a big ol' 2mm hogger on a given part.
Or in other words, you call that a knife?
Do you have a link for this cutter? We have other Harvey stuff here but I didn't know you could get 7-flutes tool this small.
Our shop uses OSG cutters for the smaller stuff, I use their 2mm diamter X 8mm loc w/ .008" corner radius 2-flute all the time.
I would probably leave more like .001"-.0015" roughing stock. For a normal cut I would run it at your full speed 12,000rpm but if you have a large area to cover would probably be best to slow it down to more like ~10,000rpm to make sure the cutter doesn't wear out before you finish a full pass.
Stepover anywhere from 10%-30% of the cutter diameter and with the 2-fluters you can run a fairly high chipload like .001"-.002" because of the lower depth of cut. But with 7-flutes you might not have enough chip clearance in the flutes so might need to experiment here.
As far as surface finish goes, you pretty much get what you get but it should be decent in S7 at 56rc. We run "MQL" oil misted into the air blast which does help surface finish, you might be able to rig something up for this or could try spraying it onto the surface manually.
The total depth of the pocket is .010 deep... it’s a pretty large surface area it’s probably around 2 inches by 2.5 inches.... and the pocket has no “corner radius” but I can’t use a tool with a corner radius on the bottom of the tool because where the OD bevel meets the pocket it has to be shap the .010 by 45 bevel sticks up off the pocket it’s a punch facedetail if you are familiar with PM
Me lost.......this make no sense. Can't have radius on the corners, equals can't
use a rotating tool in my mind. I think your right this is way beyond me. Pardon me for the interruption.
Mike1974
Diamond
- Joined
- Nov 5, 2014
- Location
- Tampa area
DMF Tom! Help him with "large surface area" please.. LoL
Sorry, nothing to offer here to the OP...
DMF_TomB
Diamond
- Joined
- Dec 13, 2008
- Location
- Rochester, NY, USA
its a small part if you can pick up part without needing a crane
its a very small part if you can pick it up with one hand
its a miniature part if you can pick it up with 2 fingers
its a microscopic part if you can hold part on one finger
its a very small part if you can pick it up with one hand
its a miniature part if you can pick it up with 2 fingers
its a microscopic part if you can hold part on one finger
Chief- Keep in mind there are limits to what milling can accomplish and a Haas is not the most rigid machine in its class. Suggest you get in touch with Robb Jack company, they specialize in tools for jobs like this and have excellent technical resources.
