# Milling 101



## JeffF (Dec 3, 2012)

I've been doing pretty well with getting used to the lathe, but I have to admit I am finding the milling machine more challenging.  It seems to me that the lathe does a lot of the accuracy work on it's own, while the mill requires a significantly greater skill level.

I was machining a piece of 1/4" aluminum plate about 2" by 3".  I clamped it flat in the vice and took an endmill in a collet and milled along the left side of the piece.  I went from front to back and as I got near the back, the mill "grabbed" several times.  This is the right direction to mill, right?

For illustrative purposes, if I were to clamp a piece in the vice, the correct direction for milling the sides of the piece would be (from the front left corner) from front to back along the left side and then left to right along the back, then back to front on the right side and finally right to left coming back across the front.

I would never do it all at once like that, just trying to confirm I'm not unknowlingly climb milling.

And, on a similar idea, how do you mill a slot in a piece with square corners in the slot?  All the mills are round, how do you get an interior corner square?

Jeff


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## mwilkes (Dec 3, 2012)

Dunno. Think you want to go the opposite way, jeff. Back to front on the left-hand edge. Front to back on the right. 

Otherwise you would indeed be climbing


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## JeffF (Dec 3, 2012)

mwilkes said:


> Dunno. Think you want to go the opposite way, jeff. Back to front on the left-hand edge. Front to back on the right.
> 
> Otherwise you would indeed be climbing


 >
REALLY!?  I have read description after description and have been unable to figure out what I am doing.  There is a video on squaring off pieces that shows a guy taking an endmill cut on top of a cube at the back of a piece from left to right, and then coming to the front and going right to left and then one final pass down the middle from left to right again.  Does it make a difference if you are milling on the edge or on top?

Jeff


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## sssfox (Dec 3, 2012)

Yes it does make a difference whether it is on the side or the top.

Do a Google search on "climb milling"


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## Swifty (Dec 3, 2012)

JeffF said:


> And, on a similar idea, how do you mill a slot in a piece with square corners in the slot?  All the mills are round, how do you get an interior corner square?
> 
> Jeff



To get a square inside corner you could always make a broaching tool out of a piece of HSS or an old broken cutter. Hold the tool in a collet with the milling machine in a low gear to stop the spindle from rotating, then using the handle for the quill, move the quill up and down while slowly moving the workpiece into the broach. Will try to set up later and take a picture to show you.

Paul.


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## Herbiev (Dec 3, 2012)

You need to go in the opposite direction Jeff. I.E feed the work into the cutting flutes.


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## Lew Hartswick (Dec 3, 2012)

The biggest problem I have with teaching the kids on the mill is making them understand, it's the material that moving, NOT the cutter.
SO!!  for "conventional" milling you move the material into the cutting edge.  For the left end as you started with in your post, You do 
feed the material from front to back. The cutter is rotating clockwise viewed from above. 
   ...lew...


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## Swifty (Dec 3, 2012)

Hi Jeff, here is how I get square corners using a home made single edge broach.









All milled and broached in about 5 minutes, grabbed a piece of gauge plate that was handy and used that for the example, just lined up everything by eye but usually take a bit more time to set up properly. This method is ideal for valve chests etc. to get square corners.

Paul.


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## MachineTom (Dec 3, 2012)

When milling AL, climb milling is the correct way to go. But you need to not overload the cutting bit. And remember to speed up the spindle when doing so, with HSS you can use a regular EM at 500 spm, a AL ground bit at 1000sfm, with carbide almost no limit. Most small machines can't make 500 sfm with a 3/8 mill which would be 6000 rpm, so just spin it as fast as the machine will go.


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## Herbiev (Dec 4, 2012)

A picture is worth a thousand words
http://emob1237.photobucket.com/albums/ff463/Herbiev1/photo-1.jpg?t=1354607602
As you can see if you are milling the left side, you start at the back corner and move the work into the cutter from back to the front


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## ShopShoe (Dec 4, 2012)

When I first started milling I used to get backwards all the time. If in doubt, shut it down, *unplug the machine*, and turn the cutter by hand to help visualize which way everything is moving. Remember it is the cutting edge and how it moves into the material that you are concerned with.

Also, some experience will help you determine how much material you can remove in one pass and how fast you can run the cutter.

--ShopShoe


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## dman (Dec 4, 2012)

yeah, you don't want the cutter to try to "climb" the part. atleast not without an anti backlash leadscrew nut or partially locking the table and having some experience to guess how much force the friction will hold. don't do this unless you are sure you know what you are doing! some times you can't help it, some plastics and certain metals (metals that are fairly hard and work harden easily like titanium) prefer climbing cuts to make good chips but you likely won't need to machine any metals like that, plastics, maybe but obviously those are more forgiving.

as far as feeds and speeds it's hard to go too fast on aluminum but don't take that as a challenge. you can really hog aluminum if you have a good steady feed and don't have to stop mid cut as long as it's rigidly mounted and you use a cutter with ample chip clearance such as a 2 flute end mill.


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## JeffF (Dec 4, 2012)

I finally understand!  Thank you everyone for taking the time to educate the idiot!

Thank you too to the group members who went out of their way to take pictures for me.  The drawn diagram makes perfect sense and the person who took the time to post the pictures of how to make the square corners really went the extra mile to help out.

It's looking like the preferred method for side milling aluminum is to use a 2 flute endmill and to rough cut with conventional milling until you get down to a very shallow remaining depth.  Then a shallow climb milling cut at high spindle speed to get the final finish. 

Jeff


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## dman (Dec 4, 2012)

JeffF said:


> I finally understand!  Thank you everyone for taking the time to educate the idiot!
> 
> Thank you too to the group members who went out of their way to take pictures for me.  The drawn diagram makes perfect sense and the person who took the time to post the pictures of how to make the square corners really went the extra mile to help out.
> 
> ...



yes that's the preferred way. aluminum can gall when you conventional mill it especially if the tool isn't sharp or it's very soft aluminum or things just get too hot. the final climbing cut leaves less galling.


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## rudydubya (Dec 4, 2012)

Jeff, I'm a little late here, but I recall a similar topic a couple of years ago started by fixit about feed directions, coincidentally titled Milling 101. T70MkIII kindly submitted a diagram he used for reference.  I printed it out and taped it to the head of my mill and refer to it any time I'm a bit muddled, which is often.

Here's the diagram - http://www.homemodelenginemachinist.com/f26/milling-101-a-9332/index3.html#post105573

Lots of discussion in the thread before and after the picture.

Regards,
Rudy


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## Darren English (Dec 4, 2012)

Just to add a little confusion..... I quite often use climb milling with various materials, If i get excess vibration or a bad finish I use clmb milling and quite often this will cure the problem.

 I must add that my milling machines are very rigid and heavy (a couple of tons), I quess this probably helps me.

Just experiment and have fun with it.


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## lensman57 (Dec 6, 2012)

Hi to all,

This is a bit off topic but could a small sharp HSS parting tool be used for broaching? 

Regards,

A.G


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## Swifty (Dec 6, 2012)

Are you wanting to do it in the lathe or in a milling machine? Trying to hold the blade in a milling machine would be a bit awkward, and trying to do it in the lathe might be a bit difficult. The biggest problem is keeping the broaching tool rigid, if its too narrow it wants to flex sideways.

Paul.


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## dman (Dec 6, 2012)

lensman57 said:


> Hi to all,
> 
> This is a bit off topic but could a small sharp HSS parting tool be used for broaching?
> 
> ...



yes if you can figure out a way to hold it lathe tools can broach on a mill. look into shaper machines. it was once fairly common to use the same tooling as a lathe the make flat surfaces. I've also seen hand ground tools used on a lathe to broach a hole in the face of the part.


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## mygrizzly1022 (Dec 8, 2012)

Hi All

One more handy diagram

Regards   Bert


http://www.home-machine-shop.com/bits/CLIMB_MILLING-2.pdf


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