Best method for drilling 5 evenly spaced holes. In a circle.

[harshman]

Use paper….lots of it!!



I have done this before however I had CAD at my disposal. If you do as well have it drawn up and printed at full scale. Place the paper over the part and use a center punch (cause I didn’t have a mill – sill don’t) and go at it. I suppose you could use a pencil and paper to do the same thing but where is the fun in that?

[astroracer]

Make yourself a jig.
Use a flat piece of 2 x 6 or a piece of aluminum plate and make an arbor that fits the center I.D. of your adapter with very little slop. Screw this to the 2 x 6.
Set the jig up in your mill, zero the center and then drill two holes spaced for your bolt pattern. Spend some time making sure the radius and 72* angle is deadnuts between the two holes. The easiest way to do this is to use a rotor. Set up the center arbor and use the rotor as a pattern.
You can now set one of your adapters in your jig and drill the first lug hole. (Don't move the jig or you'll have to re-zero the holes to your cutter.) When this is done rotate the adapter 72* and pin it through the "extra" hole in your jig. This establishes the 72* angle so it had better be right. Drill the next hole, spin the adapter again, pinning it through this new hole to the jig.
You can drill all five holes this way and if your jig is right the adapter will be right.
Have fun
Mark

[Matt@RFR]

Mark, with all due respect, you're making it too difficult.

RJ, You allready know the best method. Clamp it to your table, find center, zero x,y. Go to your coordinates and drill. Easy.

If I were you, I'd either use an endmill and plunge it, or drill undersize and ream to your final size. Much more accurate and consistent that way.

If you want to get fancy, then you chamfer the outside of each hole, and use a small dovetail cutter to put a nice chamfer on the inside of each hole to ease installation.

...Well damn, I have a picture of one I did, but it's too big. I'll email it if you want to see.

[astroracer]

Mark, with all due respect, you're making it too difficult.

It's not difficult at all Matt;
Actually this is very easy and it makes drilling the adapters a very quick process ONCE the jig is made... Make the jig using the rotary table to drill two holes and the rest of the process is simply drill and pin. I use this process all the time for making model car wheels and it sure beats having to worry about getting every tool move exactly right every time. It turns the process into a no-brainer, especially if you are doing a few pieces.
Mark