Hey XL I sent you a PM, well I took the angles to work and we put them on the granite slab and use the precision squares and one was dead on and the other was like 88.5 degrees. Also on the that one the slots were almost a 1/4" shorter that the other. Those angle are 1/8 x 1-1/2 x 1-1/2 I'm going to order some 3/16 x 1-3/4 x 1-3/4 and make some new ones see if that helps. So in the meantime I downloaded a template from payloadbay.com mounted it on the foam board, cut it out placed it on the rocket and boom fins lined right up. I think I'm going to put the Macklin back on the shelf and come back later with fresh eyes.
There is know one best way to attach fins, but every good way starts with holding the rocket's airframe securely. IMO the best “tool”, for doing this is the Macklin Jig. You’ll notice I left out the word “fin” intentionally. That’s because attaching fins is probably the least of what you will use it for. Now it does it very well, but really how much time do you spend attaching fins? In fact, if you own one and it’s not on your bench most of the time, then you are not putting your investment to good use. Here are just a few examples of use in just the last few days…
Simple cradle to sand inside the airframe.
To quote Mona Lisa Vito "Dead-on balls accurate" alignment and installation of rail guide weld nuts.
... and oh yes, fins, but because these fins are "thru-wall" and have a tapered profile, a laser cut fixture provides tip-to-tip alignment to a fraction of a millimeter. Again its about holding the rocket securely.
Sometimes its about holding the "tool", that holds the rocket. When one Mackling Jig is not enough.