Deburring? how? how much? with what?

[rmorton]

So the first question of many:

 

I have got the main parts for the tail fin sorted out and will start cleaning them up. After running a demurring tool along the edges it seems to have "pulled" at ally in places and seems best suited to areas where there are sharp long burrs. I have also rubbed the parts down with red scotchbrite, which seems to do a better job of demurring for the majority of the edges. Any advice welcome

 

 

[rgmwa]

Good general reference here for all sorts of things: http://vansaircraft.com/pdf/revisions/RV-ALL_05.pdf

 

A 10" file works well on long edges. Small flat and round files or deburring tools for corners and cutouts. Maroon Scotchbrite works well for smoothing edges. A Scotchbrite wheel on a bench grinder is also very useful.

 

rgmwa

 

 

[IBob]

And really nice description from Nobody, here:

 

Savannah S Build Notes - Some Tools

 

 

[bexrbetter]

I have corresponded with 2 major rivet companies recently and they advise that as long as all large burrs are removed then that's about all you need to do, along with clean joint surfaces.

 

 

[Hargraves]

From the little iv,e heard from sav owners here corrosion proofing of all mating parts and joints regardless of what the factory has done would be my absolute priority.

 

 

[rmorton]

Thank you for all the comments and links. I have read the Vans instructions some time ago and it is very good advice. It also points out that the Ali used by vans is more prone to cracking than the Savannah if the edges are not smoothed.

 

So after much cogitation, swearing and time, I have decided on my strategy:

 

1. file off the small nibs left by the cutting process with a fine toothed file.

 

2. using a deburring blade remove sharp edges from the larger punched holes and smooth with red scotchbrite

 

3. run all edges and rivet holes over a scotchbrite wheel

 

4. run fingers over all edges and holes

 

5. check for blood

 

next step is to clean the Ali ready for corrosion protection... will get back when I have tried it.

 

 

[Marty_d]

Don't know if it helps, but I've found the following useful for deburring.

 

Drilled holes: Using a flat file (or cut down segment of file, useful for getting into tight areas), just file over the hole until all burrs removed. I've been advised never to countersink.

 

Edges: I tried using a flappy sandpaper bit on the pedestal drill, which can work, but tends to quickly get slots worn in it from the sharp aluminium. These days I just use the file again.

 

 

[rgmwa]

This tool is good for deburring drilled or punched holes. Just one or two light turns is all it takes as you definitely don't want to countersink them, just take the sharp edge off. Using a flat file will take off any raised burrs but can still leave a sharp edge to the hole which is likely to contain tiny nicks and gouges. These can become effective stress raisers and lead to cracking. What you want is a smooth transition at the edge of the hole, but without countersinking it. If you don't want to use a deburring bit, then rubbing the surface with red Scotchbrite after filing is probably a good idea.

 

Hex Shank Hole Deburring Tool DB04 - Cleaveland Aircraft Tool

 

rgmwa

 

 

[facthunter]

I don't like the idea (in principle) of filing. You are not allowed to scribe lines on aircraft sheet metal and a file scratch is worse if it leads to the hole, or to a lesser extent, anywhere else. It's a crack waiting to propagate from where all cracks start. The hole. Nev

 

 

[Sloper]

l use fine felt tip pens, buy them in bulk.

 

regards Burce

 

 

[Hargraves]

Quite right sir (facthunter) greatly exacerbated by very thin material thickness and as bad as countersinking the same. The edges almost need a rolling non cutting process of sorts. I think the Cleavland tool advised by rgmwa is closest to what would be best by the look of it. Ie no relief cut back on the leading edge of the tool to prevent or at least control any cutting action. Thats my twobob for what its worth sir. Wish you well with the project. Cheers.

 

 

[rmorton]

So far (which isn't very far) I have removed the tags from the edge of each part with a file then a rub down with scotch bride has been enough to do the rest. There were one or two of the larger circular cuts that needed a demurring tool.