In order to avoid compounding the variability I took extra precautions to ensure each hole was as close as possible. It worked out really well this time and I saved a good amount of cash by drilling the holes myself rather than buying the rails pre-drilled from FLA (not to mention the time I would have spent waiting for them to be shipped and get here )
For those of you willing to take the venture into making your own rails heres what I did.
Set up a guide to make sure your at least the same distance from the edge each time. I used a small piece of aluminum angle I picked up from Lowes Use a center bit or a counter bore bit to start a small pilot hole. Use some cutting fluid with every hole you drill. It makes things go so much better...like butter. lol not really but it did make a big difference. After you have each of the holes started, move up to a drill bit about half the size of the final 3/8 bit your going to use. Any thing will do, just make sure you use the cutting oil. With this bit you can either go all the way through or only partially. Both are good but we found that not going all the way through helped to hold the cutting fluid when you move up to the final 3/8 bit.
Here's a couple pictures of the setup I had going on the drill press. It worked really well.
Once all the holes are cut it all goes together like seen in the drawings. An interesting side note is that the assembly forum post that I mentioned
Yeah that one. It shows him placing the carriage bolts on the 8020 and then tring to get the rail to go on it. That seems really difficult so I just put a bolt and nut in each of the holes and slid the rail into place. It only took a couple minutes. One of the legs was a wee-bit (sp?) close but in the end it all worked out.
This machine is without a doubt the most sturdy machine I've attempted to construct so far. I feel confident that it will withstand the abuse were going to put it through.
Ok so whats next? Next I need to drill the holes for the Y rail. Mount that and the associated bearings. Drill the Z axis rail and mount that plate.. Then comes the hard part.... Finishing. Ive got some power train parts I need to order but that going to wait until I get the table assembled.