Hi Marc,
Using a Sherline Mill for bushing can be very accurate.
You'll need a little basic tooling to get setup for it but not much actually.
First thing of course is to choose the type of bushing system you plan to use as discussed earlier in this thread, IE: Bergeon, KWM etc. You can purchase the reamers you'll need from Timesavers or other suppliers.
You'll need to purchase a collet to fit your reamer shank if you don't already have one.
You'll then need a way to secure the clock plate to the table for locating and reaming. Again you may already have these clamps since Sherline does include them in some of their packages.
You can choose from a few different types of clamps from Sherline. "L" Clamps are simple to use and straight forward. You can get sets that come with the "T" nuts and screws. See pics. below. Check them out at Sherline
Sherline also sells Step blocks and clamps. More versatile but can take a little more time to set up. You can see the "hold down set" here:
and how they are used with the step blocks here:
You'll need a couple of square or rectangular bars to lay the plate onto and clamp down on. If you're using "L" Clamps then you'll want something about the
thickness or a little less than the clamping height of the clamps. If it's thicker you can always put some spacers under the L clamp feet.
If you're using step blocks and clamps then height isn't really an issue since this is adjustable. Just want to make sure you're up high enough so that the reamer (or end mill) can clear the plate without danger of hitting the table.
If you plan to put the bushings into the plate while on the mill rather than waiting until the plate is removed from the table then you'll need to make a brass or steel bar that can fit through the hole in the spindle. A nice slip fit is preferable. The problem with this method is that you'll need to slide something under the hole to support the plate before driving the bushing in.
Locating original hole center: Unlike the bushing tool where the base is stationary and the plate must be un-clamped and moved into position for each hole, the mill has an X-Y table that allows for very precise locating. Using the tapered centering tool (should come with reamers) and magnification you can dial the hole in to exact position. Another way which works much better for me than the tapered tool is to use pin gauges. I'm not sure how much a set of these goes for now as I bought mine many years ago but they were fairly expensive back then. They are used for inspection work in machine shops and can be purchased from any machinery supply house. The tapered center will work fine though so don't sweat the pin gauges if you don't have them or don't want to spend on them right now.
Hope this helps Marc,
Bob
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