# Using End Mill For Side Milling



## HBilly1022 (Feb 18, 2016)

I'm new to milling and just getting some hours in with the new mill. I've squared up a block and my el cheapo vise that came with the mill and things were looking good until a few hrs ago. I finished using a 3/4" end mill to face 4 sides of a 1 1/2" thick mild steel block that was 3" wide and 6" long and figured I would use the end mill to side mill the ends of the block, rather than try to stand it on end and get it square to the other surfaces. Started out ok but I noticed it was getting harder to cut so I stopped and checked the cutter. The bottom sides of the cutter that were below the DOC were still very sharp but the sides of the cutter that were doing the work were dull. I started taking 0.005" deep cuts and backed off to 0.002" as I progressed but dull is dull and it was obviously not getting better so I stopped.

Is this the wrong way to go about side milling and if so what is the right way?


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## GK1918 (Feb 18, 2016)

Thats what it looks like 'dull & duller".   If something you are doing time to time, I would
buy a roughing end mill then finish with a new end mill.  We get into this a lot and thats
why we have a shaper.  The reason, there are no suppliers around here for end mills, so
if in the middle of a job & break or dull one, thats time waiting for UPS, and the old story
everybody wants something yesterday.  Such a shame, if this was in the 1950s I could 
walk & get anything right here, the famous Lincoln twist drill mfg. end mills gear cutters
you name it, now there's low cost housing there now...... I'm now ranting again wife says
I'm whining again?  
sam


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## TommyD (Feb 18, 2016)

Sounds like a cheap end mill. Buy a good name brand or, as suggested a rougher but buy GOOD quality cutters. They may cost more initially but will make up for it in how long you are able to use it.

Do you know the difference between conventional and climb milling? With those depth of cuts it sounds like climb milling.


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## Billh50 (Feb 18, 2016)

Some of the cheap endmills are not sharpened right and will not last. I always buy name brands for endmills. I was taught to conventional mill on a manual mill, unless I am only taking a skim cut. The reason I was told this is because if for some reason the table jumps the endmill will grab the part and pull it right out of the vice and also gouge the part. I have seen this happen many times through the years.


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## Karl_T (Feb 18, 2016)

+1 What everybody said about sharp cutters.

Cutting on the side REALLY benefits from a rigid setup. A good vice and clamping the axis not in use help. Now, your mill is the limiting factor. The DOC that you can best remove at once will need to be found by trial and error. I can take .100 deep by 0.025 wide at a time on my Excello. The Supermax will easily do .25 deep by 0.025 wide on the side.  Years ago, my clapped out bridgeport really struggled with this cut. Using a ruffer and then a skin cut with a new end mill was about the only way to get er done.


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## planeflyer21 (Feb 18, 2016)

All good advice!

What's your experience with knives?  Same concept.  I used to think that a knife is a knife is a knife, and hooboy were people stupid for paying $_____ for one.  Then I had a nice pocket knife that I used daily and didn't need to sharpen one blade for years, after having some that needed constant sharpening with great effort.  Hhmmm...


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## Bob Korves (Feb 18, 2016)

Scale and corrosion on the work will prematurely dull the cutter.  I usually run a flap disc over rough skinned material with an angle grinder before putting it in the vise.  Don't know if that was an issue for what you were doing...


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## mmcmdl (Feb 18, 2016)

End mills are made to " cut " and not " rub " material off . Same as a drill . With proper speeds and feeds they'll live a longer life . A rougher " corn cob " end mill will chew material off like there's no tomorrow providing you have the proper set up . As stated above , conventional cut when roughing , climb when finishing . Better finish without the " hairs " .


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## Metal (Feb 18, 2016)

Also depending on your speed you could have been heating up and hardening the steel, the end might have been cutting, but the sides could also have been rubbing and warming things up which would explain why they dulled out.


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## HBilly1022 (Feb 18, 2016)

Thanks for all the replies, a wealth of info here. Looks like I need to get a roughing cutter and stop using these cheap end mills for side milling.



Bob Korves said:


> Scale and corrosion on the work will prematurely dull the cutter.  I usually run a flap disc over rough skinned material with an angle grinder before putting it in the vise.  Don't know if that was an issue for what you were doing...



Were you in my shop watching what I was doing, lol. That is exactly what I did. I have a bunch of mild steel I get from the scrap steel yard and that is what I use for just about all of my projects. The piece I was playing with / learning was indeed covered in mill scale, rust and generally in rough shape. Next time I will take a grinder to it before it goes into the mill vise or lathe.



TommyD said:


> Sounds like a cheap end mill. Buy a good name brand or, as suggested a rougher but buy GOOD quality cutters. They may cost more initially but will make up for it in how long you are able to use it.
> 
> Do you know the difference between conventional and climb milling? With those depth of cuts it sounds like climb milling.



Not sure about the climb cut. Is it the same as using a router in woodworking? When cutting along the edge of a work piece, a climb cut would be moving the cutter towards me, if the work piece is on the left side of the cutter (or in the case of milling machine, moving the table to the left with the cutter being on the backside of the work piece). Is that right and if so, should I be using a conventional or climb cut when doing edges?


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## mmcmdl (Feb 18, 2016)

If you can take a deeper cut to get under that scale with your end mill , you wouldn't be cutting it . You would then be cutting your material and just pushing off that scale as the tool breaks out if that makes sense .


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## Metal (Feb 18, 2016)

HBilly1022 said:


> Not sure about the climb cut. Is it the same as using a router in woodworking? When cutting along the edge of a work piece, a climb cut would be moving the cutter towards me, if the work piece is on the left side of the cutter (or in the case of milling machine, moving the table to the left with the cutter being on the backside of the work piece). Is that right and if so, should I be using a conventional or climb cut when doing edges?



Its kind of more complicated with a mill, but the same idea.

Basically if you imagine the recoil force being put on the part, if it is pushing backwards against the direction of the mill, that is "conventional" milling, basically if there is any backlash, its being taken up by the mill pushing back against the leadscrew
climb milling is the opposite way, if the mill has backlash and the recoil forces exceed the force it takes to move the table, it will cause the endmill to jump forward and drive into the work, a really bad situation, but otherwise if taking very light cuts, it gives a much nicer finish.

// just imagine the endmill being a wheel and your work being the road, if its going against the direction you are going, that is conventional, if it is "helping" the mill along, that is climb


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## mmcmdl (Feb 18, 2016)

Perhaps this may help if you can see it . You'll get the hang of it with practice . Hmm...........the new Victoria Secret catalog just arrived !!! Good luck .


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## Bill C. (Feb 18, 2016)

Conventional milling the chips will be ahead of the cutter and material. I would use at least a one inch end mill. I agree with the poster get a couple quality end mills.  I used to square up a lot of saw cut stock from plate stock.  Depending on quality sometimes both methods had to be used under power table feed.  Climb milling the cutter tries to climb on top of the stock  The table clamps need to be snug,


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## HBilly1022 (Feb 18, 2016)

mmcmdl said:


> If you can take a deeper cut to get under that scale with your end mill , you wouldn't be cutting it . You would then be cutting your material and just pushing off that scale as the tool breaks out if that makes sense .



That absolutely makes sense. I'm still a little nervous about taking too much DOC but I read somewhere that too little is harder on the cutter than a deeper cut. Part of the learning process I guess.



Metal said:


> Its kind of more complicated with a mill, but the same idea.
> 
> Basically if you imagine the recoil force being put on the part, if it is pushing backwards against the direction of the mill, that is "conventional" milling, basically if there is any backlash, its being taken up by the mill pushing back against the leadscrew
> climb milling is the opposite way, if the mill has backlash and the recoil forces exceed the force it takes to move the table, it will cause the endmill to jump forward and drive into the work, a really bad situation, but otherwise if taking very light cuts, it gives a much nicer finish.
> ...



I don't understand the backlash part but the travel direction sounds like using a router. The simple rule I learned was to take your right hand with index finger pointed up and the thumb extended to the left. Your thumb points to the work piece and your index finger points in the direction of the cut, ie router travel direction. That would be conventional cutting. Does this work with milling or am I still missing something?


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## Metal (Feb 18, 2016)

HBilly1022 said:


> I don't understand the backlash part but the travel direction sounds like using a router. The simple rule I learned was to take your right hand with index finger pointed up and the thumb extended to the left. Your thumb points to the work piece and your index finger points in the direction of the cut, ie router travel direction. That would be conventional cutting. Does this work with milling or am I still missing something?



Well mills aren't limited to one direction of rotation, so it could be one way or the other depending, which way is your mill spinning?


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## Steve Shannon (Feb 18, 2016)

HBilly1022 said:


> That absolutely makes sense. I'm still a little nervous about taking too much DOC but I read somewhere that too little is harder on the cutter than a deeper cut. Part of the learning process I guess.
> 
> 
> 
> I don't understand the backlash part but the travel direction sounds like using a router. The simple rule I learned was to take your right hand with index finger pointed up and the thumb extended to the left. Your thumb points to the work piece and your index finger points in the direction of the cut, ie router travel direction. That would be conventional cutting. Does this work with milling or am I still missing something?


I just think of it like this: when you're climb milling (or climb cutting with a router) the direction of linear travel is the same direction (but at a lower speed) the cutter would pull your workpiece. In conventional cutting the cutter is being forced against the work.
Mmcmdl's drawing shows it perfectly. 


 Steve Shannon, P.E.


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## mmcmdl (Feb 18, 2016)

HBilly1022 said:


> That absolutely makes sense. I'm still a little nervous about taking too much DOC but I read somewhere that too little is harder on the cutter than a deeper cut. Part of the learning process I guess.



As with everything in life , machining comes with a learning process . In time , you will learn to trust your tooling , set-ups and your own judgement as to what the machine is capable of doing . Same as electricity . Be respective of it , but not afraid of it .


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## HBilly1022 (Feb 18, 2016)

Metal; unfortunately my mill only rotates clockwise. A reversing switch is an option with this mill. Should make it easier to figure climb cut direction though.

Steve; that is exactly how I envision it, the cutter wants to pull itself along the work or it is being forced into it. I hadn't thought about the lower speed issue though and now that you mention it mill seemed to be happier in a conventional cut than a climb cut. Now I know to slow down when climb cutting.

mmcmdl; I'm in a lenghty learning process as of late. In the last 2 months I bought a metal lathe, metal cutting bandsaw and now a mill. I'm just scratching the surface of the lathe learning process and now starting on the mill. I thought the bandsaw was easy until I ruined a good band by using a blade that was too coarse for the thin wall material I was cutting. Oh well.


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## TommyD (Feb 18, 2016)

Backlash is the slop between the feed screw and the nut that moves it. Move the table in one direction then change to the reverse direction, the amount that the handle/number collar moves before the table moves is backlash. 

Feed and speed for cutters can be found on line or Machinery's Handbook. Too fast of cutter speed  will spit out hot, blue or brown chips. Too slow cutter speed and DOC will cause you to really have to crank the handle to cut your material and, possibly, break your cutter.


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## TommyD (Feb 18, 2016)

You always want your material to feed into the cutter, right side of the cutter 12 o'clock, clockwise, approaching the cutter from the 3 o'clock direction....clear as mud? It's material approach to the cutter direction, you want the open side of the cutter, the chip gullet, to engage the material first from whatever direction you are cranking.


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## mmcmdl (Feb 18, 2016)

HBilly1022 said:


> I thought the bandsaw was easy until I ruined a good band by using a blade that was too coarse for the thin wall material I was cutting. Oh well.



And I bet you learned that those sawteeth are HOT when you wipe them out and they fly down your shirt  !!! LOL ! I'm laughing with you and not at you btw .


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## royesses (Feb 18, 2016)

I printed out one of the drawings and taped it to the wall next to my mini mill. It helps when I get a senior moment and get confused.


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## HBilly1022 (Feb 18, 2016)

mmcmdl said:


> And I bet you learned that those sawteeth are HOT when you wipe them out and they fly down your shirt  !!! LOL ! I'm laughing with you and not at you btw .



Ha ha the chuckle is on you  LOL ..... the band doesn't get hot because I always run the lube pump when I'm cutting. I did run the saw once without the lube and found that the material got really hot though. BTW I never thought you were laughing at me. All is good. This is a friendly forum. Lots of help and friendly banter.



royesses said:


> I printed out one of the drawings and taped it to the wall next to my mini mill. It helps when I get a senior moment and get confused.
> 
> 
> 
> ...



That picture is exactly what I was describing with the right hand gesture. Maybe my explanation was lacking or might appear to be backwards because with a handheld router it is the machine / cutter that moves and with a mill it is the work piece that moves. I find the hand gesture to be easy to remember and use. But maybe in another week or 2 I may need to post that picture on the wall behind my mill as I've noticed the memory is quickly fading ..... now what were we talking about.


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## Karl_T (Feb 19, 2016)

There is one type of side milling where conventional milling is specifically NOT recommended. That is, woodruff or keyseat cutters. Manufactures suggest climb milling on these. I can see why, chips clear better with less recutting. Put an air blast on it and re cut is almost zero.


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## HBilly1022 (Feb 19, 2016)

Karl_T said:


> There is one type of side milling where conventional milling is specifically NOT recommended. That is, woodruff or keyseat cutters. Manufactures suggest climb milling on these. I can see why, chips clear better with less recutting. Put an air blast on it and re cut is almost zero.



Thanks for the heads up on that. I haven't yet done any of that milling but am anxious to. Got to get the cutters first though.


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## Scruffy (Feb 20, 2016)

I know the difference but some of these explanations had me scratching my head. Royesses picture easily shows the difference.
Thanks ron


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## TC0853 (Feb 20, 2016)

GK1918 said:


> Thats what it looks like 'dull & duller".   If something you are doing time to time, I would
> buy a roughing end mill then finish with a new end mill.  We get into this a lot and thats
> why we have a shaper.  The reason, there are no suppliers around here for end mills, so
> if in the middle of a job & break or dull one, thats time waiting for UPS, and the old story
> ...





GK1918 said:


> Thats what it looks like 'dull & duller".   If something you are doing time to time, I would
> buy a roughing end mill then finish with a new end mill.  We get into this a lot and thats
> why we have a shaper.  The reason, there are no suppliers around here for end mills, so
> if in the middle of a job & break or dull one, thats time waiting for UPS, and the old story
> ...


Maybe..........but you're right


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## TC0853 (Feb 20, 2016)

HBilly1022 said:


> I'm new to milling and just getting some hours in with the new mill. I've squared up a block and my el cheapo vise that came with the mill and things were looking good until a few hrs ago. I finished using a 3/4" end mill to face 4 sides of a 1 1/2" thick mild steel block that was 3" wide and 6" long and figured I would use the end mill to side mill the ends of the block, rather than try to stand it on end and get it square to the other surfaces. Started out ok but I noticed it was getting harder to cut so I stopped and checked the cutter. The bottom sides of the cutter that were below the DOC were still very sharp but the sides of the cutter that were doing the work were dull. I started taking 0.005" deep cuts and backed off to 0.002" as I progressed but dull is dull and it was obviously not getting better so I stopped.
> 
> Is this the wrong way to go about side milling and if so what is the right way?


Is there any chance you got the sides of those end mills hot and untempered them. One of the inherent weak links in using HSS cutters.


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## HBilly1022 (Feb 20, 2016)

I don't think it got hot but it's possible. There is no color change visible and I don't recall that happening while cutting.


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## Tozguy (Feb 21, 2016)

If the mill is dull it is rubbing not cutting. Something will get too hot real quick. On one of my first milling jobs, cutting a 1/4'' slot 1/4'' deep with a 1/4'' mill (another no-no) in tool steel with manual feed, she started off great but soon started to complain so I just cranked harder. Then the fireworks started. What a show! It seems that I did something wrong. That's why I'm here listening.


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## HBilly1022 (Feb 21, 2016)

Tozguy said:


> If the mill is dull it is rubbing not cutting. Something will get too hot real quick. On one of my first milling jobs, cutting a 1/4'' slot 1/4'' deep with a 1/4'' mill (another no-no) in tool steel with manual feed, she started off great but soon started to complain so I just cranked harder. Then the fireworks started. What a show! It seems that I did something wrong. That's why I'm here listening.



I'm glad you posted this. I haven't tried cutting a slot with the mill yet but what you describe would have been exactly the way I would have approached the task. Although I will be milling mild steel mot tool steel, if that makes a difference. I guess I better research slot cutting before starting that project. So much to learn.


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## TC0853 (Feb 21, 2016)

Tozguy said:


> If the mill is dull it is rubbing not cutting. Something will get too hot real quick. On one of my first milling jobs, cutting a 1/4'' slot 1/4'' deep with a 1/4'' mill (another no-no) in tool steel with manual feed, she started off great but soon started to complain so I just cranked harder. Then the fireworks started. What a show! It seems that I did something wrong. That's why I'm here listening.


I haven't cut hundreds of slots, but my experience has shown me that for some reason, cutting a round slot (with a ball end mill) I seem to be able to cut faster and deeper (and quieter) than when cutting a square slot. Just the other day I machined a 5/16" round slot 5/16" deep, and it just went through nice and quiet, then reverse the direction so as to polish it up, and it looked like a mirror inside. I checked the depth and width and they were right on. It seems to me also that rather than just poke along, get the machine up to speed and do as much as it will do comfortably and quietly.


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## Tozguy (Feb 21, 2016)

The slot had to be square on the bottom although I can understand how a ball end cutter would do a better job in some situations. It was a bad idea to use a regular 4 flute mill the same size as the slot. It was cutting on 180 deg. i.e.both sides of the slot at once. No much room for chips to get out of there. Apparently a smaller mill with two or more passes would have been a better way. I am going to get some roughing mills ...they look real mean and a cooling/lube system....they look real cool.


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## benmychree (Feb 27, 2016)

HBilly1022 said:


> I'm new to milling and just getting some hours in with the new mill. I've squared up a block and my el cheapo vise that came with the mill and things were looking good until a few hrs ago. I finished using a 3/4" end mill to face 4 sides of a 1 1/2" thick mild steel block that was 3" wide and 6" long and figured I would use the end mill to side mill the ends of the block, rather than try to stand it on end and get it square to the other surfaces. Started out ok but I noticed it was getting harder to cut so I stopped and checked the cutter. The bottom sides of the cutter that were below the DOC were still very sharp but the sides of the cutter that were doing the work were dull. I started taking 0.005" deep cuts and backed off to 0.002" as I progressed but dull is dull and it was obviously not getting better so I stopped.
> 
> Is this the wrong way to go about side milling and if so what is the right way?


You don't say anything about cutting speed or lubricant, and in general too light of a cut will tend to dull any cutter,  For soft steel, cutting speed should not exceed about 100 ft. per minute, and lubricant is a necessity.


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## DLW972 (Feb 27, 2016)

Hi,

Just joined the forum. This is my first post. I've read this entire post and haven't seen mentioned anywhere something that's important to understand regarding end mills. Unless a plunge cut is being made, the _end_ of the mill is not doing any cutting. Only the circumference (side) of the mill is cutting. This is true whether a skim cut is being made to true the top of a work piece, whether milling a .250" step along an edge, or using the entire cutter length to square up an edge. Likewise, only the end of the cutter is cutting when a plunge cut is being made. This may seem common knowledge to many, but those new to milling will progress more quickly if they understand concepts.

Regarding this OP's question, I believe others have touched on the probable cause. Cutters, especially those of lower quality, are highly susceptible rapid dulling when forced and/or run too fast. Heat develops and causes loss of temper, which dulls the cutter. A dull cuter rubs rather than cutting, which generates more heat and the cycle repeats until the cutter _rapidly _becomes useless. It is important that speed and feed not be exceeded based on the material being worked and the type of cutter. Speeds and feeds are something that are covered extensively in _Machinery's Handbook_ and probably can also be found online. Use of good cutting fluids/coolants is also recommended for many operations..

All is not lost for the end mill in the OP's post, as it sounds as if it can still be used up to the point where it dulled.

Hope some will find this helpful.

Lee


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## royesses (Feb 27, 2016)

Welcome to the forum. I'm sure many will find your post helpful.


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## Chuck Torman (Feb 29, 2016)

One other thing to consider is the material being machined, you mentioned that you use scrap for your projects, so I assume that you don't know exactly what it is. I'm not an expert on steel but it is my understanding that most of the hot roll stuff that comes from across the water is a mixture of a little of everything, "hard, soft, various carbon and alloy contents" so you really don't know what you are getting. My experience with some of this stuff is that I will be merrily cutting along and suddenly everything goes to crap, like I just hit a ball bearing or something (usually ruins the cutter too). When considering the cost of quality cutters these days, might be penny wise and pound foolish to use good quality cutters on cheap scrap of undetermined content and quality,  just a thought? Good luck and keep your enthusiasm.


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## HBilly1022 (Feb 29, 2016)

Good point Chuck. I'm not sure I want to use any good quality mill ends just yet. I'd rather screw up cheap ones while I'm learning, especially since I don't know of any sharpening services nearby. I get your point about the better ones being more resistant to wear and abuse though. I'm in the process of making an adapter to use my little air grinder for sharpening the ends of mill ends on the lathe. If it works then I should be ok with the cheap ones for a while. I tried using the 3" facing mill that came with the mill and really like it. The only thing is I chipped 2 of the 4 carbide tips and it doesn't cut well any more. I've tried sharpening them but no success yet. I replaced them with some HSS bits that I ground myself and they work fine for aluminum but so great for mild steel. I'll just keep at it until I figure it out or I'll be back here asking for more help.

It's good to know there is always help available from the forum members.


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## HBilly1022 (Feb 29, 2016)

benmychree said:


> You don't say anything about cutting speed or lubricant, and in general too light of a cut will tend to dull any cutter,  For soft steel, cutting speed should not exceed about 100 ft. per minute, and lubricant is a necessity.



Sorry for the late reply, I must have skipped past your post. I haven't been using any lube up to now but in the last couple of days I have tried cutting fluid that I use on my bandsaw but didn't see any benefit from that on mild steel. Probably the wrong stuff. 

My cutting speed is based on 90 fpm surface cutting speed for HSS on mild steel and  2 x that for carbide. I made up a spreadsheet for the various diameters and materials I plan on using and have it posted next to the mill.


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## Skibo (May 5, 2016)

Scruffy said:


> I know the difference but some of these explanations had me scratching my head. Royesses picture easily shows the difference.
> Thanks ron


A pictures worth a thousand words


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## visenfile (May 15, 2016)

Is "mild steel" hardenable ?  I thought it got its name because the  carbon content was too low to harden.  I know that tin can lid bending will "harden" the material at the facture area. Perhaps a matter of degree, how deep?


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## kizzap (May 20, 2016)

From what I have read, (and by all means I am not an expert in this, go do some research), is that mild steel on it's own is not really able to be hardened. However you can case harden mild steel, which involves impregnating the steel with some form of carbon


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