I understand what you are saying Quillman but with all due respect, +/-0.010” is an order of tolerance that I would expect from someone using a pedestal drill. This is a total deviation of in excess of 1/2mm. A CNC machine should be easily capable of working to tolerances in the order of +/-0.0004" (+/-100 microns). Of course the tighter the tolerance the higher the cost due to higher quality machinery costs, more tool passes, more frequent tool tip changes, etc., and therefore as you say, it is possible that the tolerance gets backed off a bit. I would however still be bitterly disappointed in the quality of a product if I could beat it with a pointed setscrew and a pencil! Working off the drawing I have is as I said in my last post, simply not an option due to the lack of detail. I guess I was just hoping someone had a proper drawing to save some work.
Cherryville Chuck you stated that “This is a tremendously dangerous practice and should never be done.” Danger is a relative subject. I have seen a demonstration of what can happen when a work piece is fed into a router table from the trailing edge side of the bit. The demonstrator also fed it in by hand – BRAVE! I wonder if this was the same demonstration you mention as I seem to remember it was a routing celeb that did it. I have to say that with a bit of forethought, concentration, fingerboards and ALWAYS feeding into the leading edge of the cutter there seems to be little danger. I also tend to run my finger boards quite tight. Certainly I have never ever had a mishap by using this approach. Also I have both the bit rotation and feed direction etched onto the router base plate on my table so I do not even have to stop and think which is the safe(er) feed direction. Having said that I have never fallen off a ladder either but we are not allowed to use these anymore as they are now considered too dangerous.
I think that you Nick are right. I guess that I am just a bit disappointed as I expected to find a proliferation of such drawings on the web when I first searched and as seems to be the case with the web, you get sucked in to try just one more search! I have considered the alternatives and if I had access to a engineering lathe and a milling machine I would probably start from scratch and make a new (better) sole plate as well as the base plates and I would dowel the sole plate so different base plates could be fitted straight on without the need for centring cones etc., with a repeatability in the order +/-10 microns. Unfortunately I am now halfway around the world from that equipment. So I am going to do what I did last time, almost. First I will rough out the plate and mount it. Slightly oversize as you did. I will have to finish cut the round base plate using the router so I will use a point bit in the router after mounting it which will give me a centre for the trammel pivot point. I will then cut it to a perfect circle, remount it and bore out the centre. All I have to do then is add the counter bores for a guide bush set etc.. I haven’t figured this bit out yet but I am sure I will find a pretty accurate way to do it!
Quillman, just had a look at your sliding dovetail joints on this site. Ni…….ce work. You obviously are a man who understands accuracy and tolerance!