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Re: Hex Broaching?
Cory,
To be specific, a .505" hex rotary broach with a 1/2" shank runs about $70 from Slater Tools, when I asked for a .500" hex rotary broach, they quoted about $80 and about 1-2 day turnaround.
There are basically two kinds of rotary broach holders, Swiss type which are non-adjustable and the regular adjustable type. Since you plan to use it in a Haas milling center, you might want to consider the Swiss type. I asked the salesperson what the advantages were between the two. The Swiss type is smaller and has more clearance (it is round) whereas the adjustable has a wide base that could cause clearance problems since you will be spinning the tool holder rather than spinning your material. Adjustable ones are nice if you have a non-standard broach with a different length. You can only use standard length broaches in Swiss type holders and are limited to a max of 1/2" shank broaches.
Last year, I tried to use it on a bridgeport type vertical mill and failed miserably. I ended up having to retram the mill and gave up. We went back to our push broach which didn't always cut perpendicular no matter how hard we tried.
Of course your Haas is quite a bit stiffer. I would not expect a problem providing you adequately clamp your work piece.
This past summer, I decided to give it another try and placed the rotary broach in the tailstock of our lathe. Surprise, it was so easy and I felt like an idiot for not trying it earlier!
According to the slater tools chart, it takes about 600-700 pounds of thrust to rotary broach a 1/2" hex in aluminum.
Because rotary broaches are driven by the work piece, the hex can have a slight twist. One work around, is to reverse the spindle half way through the piece to reverse the twist. Rotary broaches don't care about spindle direction for cutting.
I'll let you know how it works out for us.
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