Let's say that I want to cut a rabbet on the corner of a block, like I'm making a strip that I will cut into T-nuts. The slot will be 1/4 inch wide, and 1/4 inch deep. Which would be a better choice: an end mill, or a side cutting mill? If an end mill, should I use a small one, like 3/8, or a large one, 1"? Would I cut the width and move down, or the depth and move in? Of course, that would apply to either tool.
Or, will they all work about the same, and no one is better than another?
(08-31-2012, 05:59 PM)Wawoodman Wrote: The slot will be 1/4 inch wide, and 1/4 inch deep. Which would be a better choice: an end mill, or a side cutting mill? If an end mill, should I use a small one, like 3/8, or a large one,
Hi Woodman,
I am a little confused - are you wanting to cut a slot ? -like a key way?
DaveH
No, a notch out of a corner. Like I said, imagine I had a strip of 1/2 x 3/4. And I want to turn it into a strip of T-nut stock. So it will look like an inverted T in section.
Not familiar with the term side cutting mill. If you use an end mill I like to use as large as possible, less deflection, chatter, or chance of breakage. Cut close to full depth and index in, on the last pass go full depth and clean up all the marks. If you index down your doing all the cutting with a narrow band at the bottom of the tool and never wearing the sides, with full depth cuts your distributing the wear.
Free advice is worth exactly what you payed for it.
Greg
Hi Woodman,
Normally one would just use an ordinary end mill and the largest (within reason) end mill you have. That being said the milling machine must be able to handle the size of end mill. So the milling machine will dictate the maximum size of the end mill one can use.
The way one cuts the profile will again depend on one's milling machine, but normally in the home workshop it is cut in away that you can "sneak" up to the finished size.
If I was cutting it on my RF30 mill I would use a 1/2" end mill set to cut 1/8" deep with a depth of cut 1/8" for the first cut, the second pass will be set so as to leave a .020" finishing cut. A total of 3 passes.
However one could set it to 1/4" deep and take two (passes) of 1/8" depths of cut, again leaving .020" as a finishing cut, on the side and bottom.
Or one can set it to 1/8" deep with a 1/4" depth of cut, then a second pass at 1/4" deep cut, again leaving .020" or so as a finishing cut.
There is no real right or wrong way, some prefer one way others another way, but most of all it will depend upon ones milling machine.
First of all, you should always buy end cutting end mills. One that only side cuts is kind of a waste because they cost pretty much the same. If you have a rigid machine, pretty much any size end mill will do. If your mill is light duty like a bench mill, choose an end mill twice the diameter of the cut you are making (1/2" in this case). That will reduce the tendency of the end mill to pull the work into it.
Here is the procedure I would use:
1) Touch the top of the work and zero the Z axis.
2) Crank the table up .240".
3) Touch the side of the work and zero the Y axis.
4) Move the end mill in .240" and take a cut. Climb mill if you are using a rigid mill, otherwise take the backlash out of the screw, lock the table and take a conventional cut.
5) Move the table up to .250" and in to .250" and take a finish climb cut.
6) Flip your part around and do it again.
If unsure, you may want to check the dimension of the part before taking a finish cut.
As you can see, there are many different ways to accomplish the same thing in machining. How you do it depends on your experience, and the type of machinery you are using. There is no one right way to do it.
(08-31-2012, 07:14 PM)f350ca Wrote: Not familiar with the term side cutting mill. If you use an end mill I like to use as large as possible, less deflection, chatter, or chance of breakage. Cut close to full depth and index in, on the last pass go full depth and clean up all the marks. If you index down your doing all the cutting with a narrow band at the bottom of the tool and never wearing the sides, with full depth cuts your distributing the wear.
Think of a side cutting mill as a thick slitting saw.
Willie,
I have a Rockwell vertical mill. "End mill" is what I mean when I refer to what you have pictured. "Side mill" or "side and face mill" is like a small, thick circular saw blade, that mounts on an arbor. So, the cutting action is perpendicular to the arbor.
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