End mill use best practice

I am fairly new to milling and in the middle of making a piece when I realized there are two ways of doing it. Well technically three ways. What is the best way or proper way to do this? Do I

a) raise the knee say.040" and then move the table over a cutters width in the X direction (left in the photo). And then feed the table in the Y direction to make the cut. and the move the table a cutters width again in the X direction and repeat until I get to the shoulder. The raise the knee again and repeat until I get to my desired depth of about .250"

b)raise the knee the full .250" and then move the cutter over say .040" in the X direction and then feed in the Y direction to make a cut and continue this unit I get to the shoulder.

or c) turn the part 90 degrees in the vice and basically do the same as option b but using the full length of the cutter.

I am assuming that option c is the worst option of the 3 because? I am doing this on a relatively light duty mill. More ridged than an import bench top mill but not as ridged as a bridgeport. I know all 3 options would work but what is the best way? What is the fastest way? And what puts the least amount of strain on a machine or is there even much of a difference?

This should be a good read. There is as resulting shoulder here?
I tend to finish shoulders or walls in climb.
Bob

Read the Machinery Handbook to find the feed/speed for your piece of metal and endmill.
Then you can determine your max depth of cut possible and use a depth that is less.

I would run the cutter down the length. You will see a dividing line between passes back and forth as you sweep the x direction and advance y.
A face mill is what I would use, a 3" one should do.

All I'm going to say is GET SOMETHING IN THAT HORIZONTAL SPINDLE to keep chips and dirt out! I'm cringing just looking at that picture. That is machine abuse, somebody call Division of Machine Welfare!

eKretz said:

All I'm going to say is GET SOMETHING IN THAT HORIZONTAL SPINDLE to keep chips and dirt out! I'm cringing just looking at that picture. That is machine abuse, somebody call Division of Machine Welfare!

Click to expand...

That has been on my list of things to do. I really have no good excuse as to why that isn't protected. But a bad excuse is I'm not really sure of a good way to do it. How are horizontal spindles normally covered on a machine with a separate vertical head? I'm just glad no one has made fun of my mill yet

Also I realized that my original question was kind of long winded and perhaps a little unclear. Basically I am wondering if it is better to take a deeper cut in the vertical direction and shallow cuts in the x direction. Or deeper cuts in the x direction and shallower cuts in the vertical direction.

Make a plug out of an old toolholder or use one of your good ones that doesn't have any exposed openings, like for example an endmill holder with the correct sized pin clamped in it.

Your original question will probably get an "it depends" from most here. Depends on the amount of stock you've got to remove, depends on the rigidity of the setup, depends on the rigidity of the machine.

Generally, you'd like to use as large a cutter as possible (facemill) to remove the bulk of the stock then switch to an endmill if necessary. At that point it doesn't really matter which of your outlines you use. As long as the machine is rigid enough I would take one rough cut if necessary with the endmill also, leaving a small finish cut. If you can rough it close enough with the facemill to only need a finish cut with the endmill do that.. Taking more cuts than needed is a waste of time...

Sadly I don't yet have a face mill. I have been getting by with just using fly cutters. I usually just turn on the power feed and let the fly cutter slowly work its way across. From what I am gathering there is really not a wrong way to make this cut and it seems to be personal preference. I have two of these parts to make and each one has two of these cut outs so I will probably just play around and see what my machine likes. Its not important and could even just be ground down for what it is so I can't really mess the part up at all.

A quick and dirty (clean?) way to do it would be to cut a square of aluminum foil that will cover the face. Then hold that aluminum foil over the spindle and shove a piece of cotton or rag through the foil and into the center to hold it in place.

Or just tape the foil in place.

For a more permanent cover I like using plastic sheet which would be held in place by the normal means of holding tooling in that spindle (a drawbar?). I get plastic sheet inexpensively and locally by purchasing those binders that are sold in the stationary stores or the school supply section at Walmart and other such stores. It is probably vinyl and will not last forever in the shop environment, but then it is cheap.

mega arc 5040dd said:

That has been on my list of things to do. I really have no good excuse as to why that isn't protected. But a bad excuse is I'm not really sure of a good way to do it. How are horizontal spindles normally covered on a machine with a separate vertical head? I'm just glad no one has made fun of my mill yet

Also I realized that my original question was kind of long winded and perhaps a little unclear. Basically I am wondering if it is better to take a deeper cut in the vertical direction and shallow cuts in the x direction. Or deeper cuts in the x direction and shallower cuts in the vertical direction.

Click to expand...

I typically go with large axial depth of cut with a small radial cut (step over) This allows you to use the entire length of the cutter versus just wearing the very end.


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Starting with your C choice, I would not mount the stock in any other orientation in the vise unless some other consideration required it. The way shown in the photo would provide the best rigidity.

It may depend on the alloy being cut, but I see no reason why you could not take a 0.250" cut in the vertical direction. I have a much smaller machine and it could do that, perhaps with a smaller bite in the X direction. If I wanted the most accuracy in the vertical direction, what I might do would be to cut perhaps 0.245" deep on the first pass and then take a measurement to allow a fine adjustment to the depth of the cut on the final pass. But if that 0.250" dimension is +/-0.005" or looser, then just go for it.

I would not cut with the full width of an end mill. That would be the X direction in your set up. That would mean that you would be employing a combination of climb and conventional cutting. At most, I would use one half the diameter of the end mill for the X feed per pass. That way you would be making a conventional cut if you move from front to back for each pass.

There is also the direction of the cut in relation to the Y movement you make before each pass. Again, feeding to the right in the Y direction and moving the tool from front to back (moving the work from back to front) you will be making a climb cut when the cutting edge is at the rear of the spindle axis. This would tend to pull the Y feed to the right and dig the cutter in deeper in that direction. For this consideration, you may want to lock the Y feed during each pass or limit the Y feed to an even smaller fraction of the cutter's diameter, perhaps 1/4. Much of this depends on the characteristics of your mill.

And yes, I would use the largest diameter cutter that I had. A face cutter with index-able (replaceable) inserts is a good choice. I also need to buy one of those. A larger diameter cutter reduces the number of passes needed.

All that being said, you may have to adjust things after making the first pass or even during it. You just have to see how the cut is working in your mill.

mega arc 5040dd said:

I am fairly new to milling and in the middle of making a piece when I realized there are two ways of doing it. Well technically three ways. What is the best way or proper way to do this? Do I

a) raise the knee say.040" and then move the table over a cutters width in the X direction (left in the photo). And then feed the table in the Y direction to make the cut. and the move the table a cutters width again in the X direction and repeat until I get to the shoulder. The raise the knee again and repeat until I get to my desired depth of about .250"

b)raise the knee the full .250" and then move the cutter over say .040" in the X direction and then feed in the Y direction to make a cut and continue this unit I get to the shoulder.

or c) turn the part 90 degrees in the vice and basically do the same as option b but using the full length of the cutter.

I am assuming that option c is the worst option of the 3 because? I am doing this on a relatively light duty mill. More ridged than an import bench top mill but not as ridged as a bridgeport. I know all 3 options would work but what is the best way? What is the fastest way? And what puts the least amount of strain on a machine or is there even much of a difference?

Click to expand...

A cork or wooden plug but with a hole or stud to pull it out. A rubber stopper is the science term. Maybe for a bathtub or sink. They make expanding rubber pipe test plugs, Cherne is one brand.
Bill D

kineticmx said:

I typically go with large axial depth of cut with a small radial cut (step over) This allows you to use the entire length of the cutter versus just wearing the very end.


Sent from my iPhone using Tapatalk

Click to expand...

+1. This is also what tooling companies will recommend. You don’t want to just use a couple percent of the length of your tool. Depending on your machine you may have to limit axial depth of cut to the cutter diameter, but even my hobby mill will do say a 1” ADoC with a 3/8” or 1/2” cutter. I’ll find a radial depth of cut that my mill will handle for a the given ADoC, usually 0.050”-0.100”.

how much are you taking off? and did you mention a shoulder?

i have learned that its best to use 60%-75% of the cutter when face milling. there is nothing wrong with repositioning the work 90% and side mill using the the full lenght of the flutes. you might even get a better finish and its a good way to get a perpendicular surface.

i you get into any kind of precision, its very usefull to think about how the cutter deflects.