Hatz Biplane Association

Dear Friend,

I shuddered a bit seeing your fingertips so close to the spinning router blade. Speaking from experience,it cost me the tip of one finger, all it takes is the blade to catch the end grain the wrong way and your fingers may have a bad day. .

When I make multiples of a part I use tracing paper over the plans and then use a spray adhesive on a piece of aluminum to attach my tracing. Using snips, band-saw or plate cutter to make a master. Using the master on my plywood stock I trace the pattern out as many times as needed and used a band-saw to cut out the pieces. If I make a mistake or need more of that part I have a master to go to. I feel much more confident following a line with a band-saw that putting my fingers near a 20000 RPM blade.

Thank you for the comments. I used a 1/4" router bit which should have worked better. Not sure why these came out sloppy. I'm going to see if I can do a better job. Thanks!

I did it like this with a 1/4 inch router bit and they came out perfect. I used thumb tacks to hold my master to the raw part.
[img]http://www.edwinwhite.com/albums/album51/P1050394.sized.jpg[/img]

Regarding #2, what is the diameter of the router bit you are using? As I recall I used a 1/4" bit which gave me an exact match at that location. You may be able to solve that one by going to a smaller diameter bit.

[attachment=0]prob14.jpg[/attachment]

Don't you just love CAD drawings? Everything is dead-nuts and as you said, it drives some people crazy trying for perfection.
I copied one of your photos so I could add some comments.
First, the plywood block is there to provide a larger glueing surface and to provide strength to the joint if someone were to "squeeze" it together from top to bottom. With that said, all glues have some degree of gap filling capabilities so the closer you can get to the lines the better.
1. The contact surface is between the cap strip and the plywood. When you clamp it you should contact the whole length in this area. If the plywood dimension is too great, it will stand a little proud and leave a bump that will need to be removed. Easy enough with a disk or belt sander and the material removed isn't enough to worry about.
2. I assume the radii are from the router. Adjust the end of the cap strip to match this area.
3. If this end is a little long, it won't matter other than the extra weight. You might consider cutting it off even with the edge of the plywood doubler.
So, to answer your original question, use what you have and smooth things out after the glue dries.

Jeff Moore

I'm trying to get everything as precise as I can, but I don't want to fall into that trap of seeking absolute perfection. I made the tail pieces, and I'm not happy with them. I'm ready to make each one individually (no master template or router), but just wanted to see what you think...is this good enough, or does it exceed the dimensions too much. As always, thanks in advance for your help.

[img]http://photos.imageevent.com/hatz/problem/large/prob14.jpg[/img]

[img]http://photos.imageevent.com/hatz/problem/large/prob15.jpg[/img]

[img]http://photos.imageevent.com/hatz/problem/large/prob16.jpg[/img]

[img]http://photos.imageevent.com/hatz/problem/large/prob17.jpg[/img]

[img]http://photos.imageevent.com/hatz/problem/large/prob18.jpg[/img]