Long reach 1/4 endmill in 6061 - Page 2
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  1. #21
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    "I'm using a larger endmill for the main passes."


    If you can get in there with a larger endmill to rough...why can't you grind the needed radius on a larger endmill. If not trying to make time on the job...remove one flute then grind the remaining flute.

    Also as to the long drill point being an issue for radius bottom. I often start with standard drill, just about to bottom then finish to depth with a hand ground drill. With a little trial and error I can usually grind a drill with a nice cutting ball tip.

  2. #22
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    Nov 2017
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    I do this sort of thing all day, injection mold engineer/machinist, since you only have 3 parts, as I usually only have 1-4 cavities, this should work, and you have some choices.
    first, if you want the material removed from the corners first, I would drill out with something smaller, D-.246 probably smaller even.
    then drill out with the end mill (or you can just drill with the endmill, it will be straighter) hi rpm (6000+)small peck .01, but stop a couple thou above the bottom.
    rough all out with a larger 1" or .75", preferably if available use a engagement path at 10%, trac path or similar.rough with decreasing sizes and lengths.
    then using different length .25 end mills rough down the remainder, .003-.005 left on the walls.
    then if you want it to look sexy on the finish, drop down in small increments with the 1 long endmill for finish path, if you use a tool with a radius you will minimize any steps in the finish wall., then hit the finial bottom with a non radius tool if they need the bottom sharp.
    using a endmill with a slightly smaller diameter would be great.but probably doesnt exist, and for only 3 parts your not going to have custom made.
    if the customer can deal you could increase the radius, every .001 counts.
    as for rpm/ipm, it is going to be horribly slow, maybe as low as 400rpm. with a .0001-.0005 chip load.
    set it up slow, one in each jaw and lights out, check in the morning.
    If you use the endmill to drill out the corners, you can mill up to the corners, but dont go into the corners, miss them by only a couple thou really.

    I am working on a injection mold right now with .093(3/32) endmill at 20X length, thats 1.875" hangout, horrible. 2500-3200 rpm 7ipm. .003 WOC left on the walls, .003 DOC finish pass. obviously you can do more than .003 DOC, I have .5° to 3°tapered walls.

    Hope this helps.

  3. #23
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    Hello. I've been a machinist for 40 yrs i love it & still learn machining tricks . That was one of my cousins favorite sayings but then he said who eats cats ? Hahaha . What about just roughing out & finish by edm ? I appreciate your time & help . Thank you god bless have a blessed day &a safe merry christmas & happy new year & love one another


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