or how about using a machine screw with a tapered head that matches the countersink of the miter bars? drill a flat recessed hole to receive the nut in the bed of the sled, with a slightly oversized through hole for the machine screw? that way, there's no need to drill the miter bar, and the oversized hole will allow for some wiggle room to facilitate any alignment issues. this could work pretty easily in 3/4" material since most nuts that small are less than 3/8" thick.
BTW, what do the instructions that come with the kreg bars say about the problem you're anticipating?
Hmm, I did use 3/4 melamine. I just don't know how I feel about a bunch of giant holes on the top of the sled. There's certainly enough support, it's not like they'd cause a problem as far as that goes. I could even cover them with bondo if I thought they were catching sawdust or whatever.
I'll be honest, I was a tad scared when I saw you mention the instructions. I hadn't read them. Now that I've read them, I know they're as pointless as I had first imagined them being. It's a single page outlining the uses of the jig, which one should already freakin' know by the time they open the package. The mention of screws is limited to listing the type of screws included. Oh wow. Like I really needed to know that.
in principle, you're right. what you're describing is how the incra bars work.
As annoyed as I am with the fact that I'm having to think about my miter bars even more than I already have, these are way better than incras, given all the cons I listed for incra on the precious page.
By the way, remember I mentioned that the kreg bars had 5 set screws the length of the bar? The package said six, but there are actually 8
on each bar, ensuring that there are still at least 2, possibly 3 set screws in the slots, even when the wood in the sled is past the blade. With the incra and it's 3 TOTAL
adjustment points, there's only one adjustment point in the slot at the end of a cut. The down side is that the actual set screws aren't 1/4-20, there're a lot smaller. But, given that the bars are 3/8" thick, there'd only be 1/16th of aluminum above or below the set screw, leaving the bar sort of weak.
what about getting a brad point drill bit that's the same size as the through hole in the kreg fixture bar and use it to mark the pilot hole for the sled attachment screws?
Good idea. I just feel I'd like the completely eliminate the possibility of the bar getting pulled to the side due to a mistake in drilling.