Quote:
Originally Posted by Chak
Can you explain how to do it right?
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So, you will need a few things.
A knee mill
A hex broach(or other broach)
The part you want a fancy hole in
Some piece of metal with square ends(like really square, you have a knee mill there is no excuse) and a hole through the middle
Your support piece needs to be at least as long as the broach or have several progressively longer pieces if you find the total travel to be in issue. Don't use multiple pieces to support this set up, it's a good way to break your $200 broach that you are trying to use cheaply. Take your sweet time.
Place your first or only support block(tube) on the back of the knee ways and make sure it is stable. Place your work on top of the support so that it lines up with the hole. Line your broach up with the whole set up doing as best as you can to have everything perfectly straight, take your time please. When you are sure you are good to go begin cranking the knee of your mill up slowly until it makes contact with some part of the turret(the part that nobody EVER moves back and forth on a mill but you could if you wanted) slides on a flat part only. Ours has a dovetail slide and we used the further down bottom flange of the dovetail. If you plan to do this often, just set up the turret so it is set up perfectly over the Y-axis knee ways.
This next part is really important.
When you are sure it's settled and ready to broach, crank the knee up a full turn and back it off to let the broach recenter itself. Keep doing this full turn back off step until you run out of travel, repeat until done. The backing off step may not be 100% needed, but it will prevent the chance of many unwanted things happening to your set up.
EDIT: Done carefully, it can be managed with one person, but 2 makes it far easier and you can take turns cranking.