What end mill for milling out slots in guards

When you go to do a drive on fit... you are only trying to drive on a 0.030" thick area that is just a tad undersize. It will drive on, and be a really nice, tight fit.

Some additional "drive off, sand guard face clean, drive back on, check fit" will be required....

....The real "key" is that you are fitting a small amount of guard shoulder to guard face, and you are fitting a thin area of the guard rather than the entire thickness.
Click to expand...

What I was trying to say, but more elegantly and thoroughly stated. Thanks Nick.
 
Carcara said:
I use key way cutters a lot which are end mills undersized .001" from 3/16. They allow for a press fit of 3/16 key stock
into a shaft.
Click to expand...

For what it's worth, most cutters are about .001" to -.002" under nominal. This is because the tool shank is almost always a negative tolerance, and then the flute are typically a bit under that.

However, that under nominal cutter can cut oversize, due to runout. And it can be tapered run out as well. Generally runout gets worse the farther you get from the spindle, so the cut makes a negative taper. But, most cuts have a positive taper due to cutter deflection. So, by happy coincidence, some of the negatives cancel out. But (obviously) it varies.
 
NickWheeler said:
Dude---- 8 hours to slot a guard?!?!? :eek:

And people like to poke me about being slow! :eek: :p
Click to expand...
Nick you are not slow, you are a nit picking perfectionist:p:D, but that is a good thing:thumbup:

Yes I am talking about 8 hours to setup, run a test piece or two and really take my time on the one I intend to use on this knife. Each time I do a guard this way I should get quicker, but even 8 hours to setup and mill is faster than how I have been doing them. I have been drilling a line of holes and them filing it out, follow by starting over because I either got one hole off or I filed just a bit too much leaving a gap:( Keep in mind I am going to be doing this first milled guard on an antique lathe, so those test pieces are going to be to find out just how out the lathe is, how consistent it is, and how much I need to adjust to get what I want. Once I get the money saved up to but a actual mini mill I am sure that I can knock a few minutes off the 8 hours:stupid::glee:
 
So I wasn't able to get a HSS 2 flute end mill locally so I will have to order one. I was able to buy a 1/8" carbide 2 flute end mill fairly cheap, they gave me a deal on it because they didn't have the HSS one they said they did when I called:thumbup: I gave it a quick test run and it cuts truer that I thought it would, the only deviation from my line was caused by my vise not being square to the carriage, something I can easily fix with a little of attention. To me it isn't that bad for a quick thumbs up alignment, .01" over 1". If I actually put the square to it I should be able to get it bang on perfect:cool: I will still do a few more test cuts tomorrow, just to make sure I have got it.


Now the first cut is a no brainer, it will be a plunge cut, but after that what direction should the end mill be traveling while cutting A or B?

direction.jpg


I am thinking A because B looks like it would be more prone to deflecting out of where I want to cut.
 
With that bit of information, climb and conventional milling, and some reading it sounds like conventional milling is what I want. I am more concerned with accuracy and saving my end mill than a nice finished surface. I will be taking shallow cuts and feeding really slow for those reasons too.
 
So it looks like I got this guard slotting thing sorted out. I made a couple of test cuts yesterday and was still getting some drifting in the slot, the first cut would be fine, but when I started the second cut to widen the slot it would drift in on itself. That is when I noticed that the Y axis on the vise was homemade and loose enough to allow the vise to move while I was making a cut. My solution was to take the vise carriage apart and add a set screw so I could lock the carriage at a set height for each cut. My last test slot worked like a charm. Only problem I am having now it getting the cutting fluid into the cutter. The cut is well covered in the machinery, the end mill is only 1.5" long, while I am working on it and the bottle that came with the cutting fluid is too big to fit in safely. My answer to that is to get a spray bottle so I can squirt fluid in from a safe distance while cutting.


Thanks for the pointers, if everything goes as well as the test cuts I should be making my first take down knife:thumbup:
 
You must log in or register to reply here.
Back
Top