Which comes first....

Good afternoon or morning or evening depending on where you are and when you read this :)

I'm thick into making my form blocks for my 750 STOL.  Trying to decide the order of operations and when making the final shape.

I've rough cut the shape of the forms from 3/4" plywood.

Should I router the 1/8" roundoff edges first, then sand the edges for "spingback" angles?

Or, should I sand the springback angle edges then router the 1/8" roundoff edges?

I'm thinking the first option makes the most sense as long as my form block dimesions aren't compromised.

The other option would be to add a routed 1/8" aluminum backing plate on each face, but that's a ton of work and expense I'm not sure I absolutely need.

Thanks in advance for all the wisdom you care to share :)

JR

Views: 292

▶ Reply to This

Replies to This Discussion

Permalink Reply by Greg Duncan on September 26, 2017 at 5:54pm

So far I have only made forms for two rudder ribs. I used 3/4" MDF and rounded the edges first with a router and then relieved the "spring back" angles with a sander. Worked well that way for me.

Not sure about the plywood but with MDF you can apply super glue to the tighter bend areas of the forms that will harden it up enough to resist deforming under more rigorous hammering.

Greg

Permalink Reply by Dan Hill on September 26, 2017 at 5:57pm

I would do the roundover before you sand the angle then sand the angle to meet the bottom of the roundover. if you sand the angle first the router bearing will ride farther in because of the angle causing your form block to be undersized. you will then also have to further blend the roundover to meet your springback angle making it more undersized. Dan.

Permalink Reply by Timothy Aanerud on September 27, 2017 at 3:05pm

Router then sand the angle.  Dan's right regarding the shaping problem if you do it in the other order.

Don't ask me why I know.

Permalink Reply by Jason R on September 28, 2017 at 6:04am

Thanks gentlemen for your input.

Time to dust of the router bit box :)

RSS

New from Zenith:

Zenith Planes For Sale 
  

Classified listing for buying or selling your Zenith building or flying related stuff...

Custom Instrument Panels
for your Zenith:

Custom instrument panels are now available directly from Zenith Aircraft Company exclusively for Zenith builders and owners. Pre-cut panel, Dynon and Garmin avionics, and more.

Zenith Homecoming Tee:

Zenair Floats

Flying On Your Own Wings:
 A Complete Guide to Understanding Light Airplane Design, by Chris Heintz

Builder & Pilot Supplies:

Aircraft Insurance:

 
 

West Coast USA:

 
Pro Builder Assistance:

 

Transition training:

Lavion Aero

K&S Aviation Services

Aircraft Spruce & Specialty for all your building and pilot supplies!

How to videos from HomebuiltHELP.com

Developed specifically for Zenith builders (by a builder) these videos on DVD are a great help in building your own kit plane by providing practical hands-on construction information. Visit HomebuiltHelp.com for the latest DVD titles.

© 2024   Created by Zenith.Aero.   Powered by

Badges  |  Report an Issue  |  Terms of Service