[MartySantic]

Anyone have any suggestions on removing the machining marks on the scalloped edge of the ribs. Using a small piece of sandpaper on the edge is going to give me carpal tunnel before it is half done. Rounding all sharp corners with a file, deburring then sanding the edge and lightening holes and then fluting is taking me 30 minutes per rib. Ideas?

 

[Jamie]

Just a note -- you shouldn't be using sandpaper on your ribs. You should be using scotch brite pads or a scotch brite wheel. The ribs should take you about 5 minutes (max) each.

Take a file to the long edges of the ribs to knock down the tooling marks..then hit it with a scotch-brite wheel. For the corners I just used the small scotch-brite wheel where I could and a rounded needle file.

This is certainly one area where the perfect is the enemy of the good.

 

[MartySantic]

The RV-12 ribs are different in that they are scalloped and do not lend themselves to running the edge down a scotchbrite wheel. Even a small 1" wheel does not work well. When I assisted with the RV-9 empenage, we did use a scotchbrite wheel as the edges on the ribs were straight. Still looking for ideas.

 

[rvbuilder2002]

The RV-12 ribs are different in that they are scalloped and do not lend themselves to running the edge down a scotchbrite wheel. Even a small 1" wheel does not work well. When I assisted with the RV-9 empenage, we did use a scotchbrite wheel as the edges on the ribs were straight. Still looking for ideas.

A regular scotch bright wheel works fine with RV-12 wing ribs...you need to hold the flange perpendicular to the wheel. tilted at an angle to the wheel face.

Hard to describe in words but rather easy to execute (I think so anyway).

 

[Alan Gilmore]

RV12 ribs

I experienced alot of frustration also. Tried lots of things and then I tried a drum sander, NICE...........

Several variations worked. A simple drum and sandpaper can be bought at most hardware stores that fits a drill or drill press. Try to get a drum that has a radius SLIGHTLY smaller that the radius on the curved edge. If it is MUCH smaller it will still work, but may be a little harder to get a nice smooth curved edge. Then, be sure to get lots of sand paper for it. The sandpaper comes in round pieces that slide onto the drum, then get "clamped" on the drum by a nut/screw on the end of the drum. Be sure to get the FINE sandpaper grade possible, otherwise it will intorduce its own rough edge. Finally, use very LIGHT pressure and keep the drum moving. This will prevent any gouging of the metal, or sandpaper.

I finally settled on using an "oscillating sander" that moves the drum back and forth so the sanding process is spread out over the whole width of the sandpaper, and hence makes it last much longer. You can do this manually, and will save you lots of bucks...about $100 for an oscillating sander. Just a sanding drum is about 15 bucks and saves you LOTS of work!!!

Note: after the sanding process, you will still need to deburr. Check my video on YouTube on how I deburred: http://www.youtube.com/watch?v=xBhJDWxetUw

After the deburring, I used Scotchbright by hand to finish the edge.

 

[MartySantic]

Thanks Alan for the ideas. Think I will just stick with my manual method. Retired here also so have the time. Rounding the sharp corners with a small file. Using my wife's nail files to get at some of the vertical edges. Using my "V" debur tool and then using small bits of 240 grit sandpaper and a lot of thumb pressure to get each scallop shiny and free of any machining marks. Maybe a bit overboard? It is going to take me about 3 good days to finish all of the nose ribs and wing ribs. Maybe if I build another I'll look into an oscillating sander. Wonder if Harbor Freight has a cheap one. Been watching your website. I have one also.

http://www.martysrv12.blogspot.com/

 

[AF_Alan]

Make your own smaller wheel

When the 1" wheel was too big for me, I wrapped a patch of scotchbrite around an old 3/16" drill bit and spun it in the drill. The scotchbrite stayed on the bit well and smoothed as well as the big wheel on the bench grinder. I got the idea from the plastic mandrel available at Avery and others.

Alan
RV-9A Wings
N984AW Reserved

 

[jte65]

Not sure why some are having trouble with a 1" wheel

The RV-12 ribs are different in that they are scalloped and do not lend themselves to running the edge down a scotchbrite wheel. Even a small 1" wheel does not work well. When I assisted with the RV-9 empenage, we did use a scotchbrite wheel as the edges on the ribs were straight. Still looking for ideas.

As Scott and several others have indicated, when done correctly, the 1" wheel works very well. I had no problems whatsoever on the scalloped edges using a 1" wheel in a die grinder. The edge quickly creates a groove in the wheel that actually helps keep things steady. And once that groove gets too deep, you just move to a clean section on the wheel. Two passes and it is done. I did go through about 3 wheels but at only $6.50 each, that is a bargain as opposed to manual methods that take much longer. I was able to do an entire rib, including lightening holes, in less than 2 minutes. No need to use other deburring tools, etc. As I think several of the other repeat builders have noted, this does not have to be absolutely perfect and shiny. Just free of burrs and smooth when a finger is run over the edge.

 

[MartySantic]

I was under the impression that all of the machining marks had to be removed from all part edges? Yes/No? I tried the 1" wheel in the drill press and it smooths the edges (and passes the finger nail test) but does not remove all of the machining marks. Comments?

 

[Jamie]

Sorry, I didn't see this was in the RV-12 forum. Therefore, I completely clueless on this gentleman's question.

 

[MartySantic]

Thanks Alan

A small 3/4" drum in the drill press turning at a low speed (320 rpm) took all of the pain out of removing all of the machine marks from the scalloped surface. I became the oscillator. Should be able to complete all of the nose ribs and the main ribs today. Again, my thanks for the idea.

 

[jamescone]

1 inch Scotchbrite wheel

As Scott and several others have indicated, when done correctly, the 1" wheel works very well. I had no problems whatsoever on the scalloped edges using a 1" wheel in a die grinder. The edge quickly creates a groove in the wheel that actually helps keep things steady. And once that groove gets too deep, you just move to a clean section on the wheel. Two passes and it is done. I did go through about 3 wheels but at only $6.50 each, that is a bargain as opposed to manual methods that take much longer. I was able to do an entire rib, including lightening holes, in less than 2 minutes. No need to use other deburring tools, etc. As I think several of the other repeat builders have noted, this does not have to be absolutely perfect and shiny. Just free of burrs and smooth when a finger is run over the edge.

If you hold the wheel at a slight angle to the edge, it will not cut a narrow groove. Also it does not take much pressure for the wheel to work.

 

[jte65]

thanks for suggestion Jim

If you hold the wheel at a slight angle to the edge, it will not cut a narrow groove. Also it does not take much pressure for the wheel to work.

Thanks Jim. I had used it at an angle but I suspect different from the angle you are referring to. It finally dawned on me what angle would work and not lead to formation of a narrow groove and I have been using that on the wing skins successfully. I did actually find the groove helpful (at least while it was shallow) on the scalloped edges of the ribs from a stability perspective. In any event, I am done deburring ribs and am only out 3 wheels!

Looking forward to seeing fuselage build photos soon (assuming you get yours in the next month or so).

 

[Gandalf]

I did actually find the groove helpful (at least while it was shallow) on the scalloped edges of the ribs from a stability perspective.

jte.. I agree that I need to be more careful with the die grinder than with the bench grinder. I ordered a second 6 inch scotchbrite wheel. I still like the 6 inch wheel on the bench grinder on long straight parts, but I am coming to appreciate the 6 inch wheel on a drill press (3000 rpm) and a 1 inch wheel on a die grinder (20,000 rpm). As Jim says I seem to get better results moving the parts at an angle across the wheel, when possible, using the drill press .

Jeff