What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

More Really Dumb ?

G

Gandalf

Well Known Member
Due to space limitations I had to start a new thread.

More of my really dumb ? and answers from:

http://www.vansairforce.com/community/showthread.php?t=33181&page=2

Dumb ? #23) How do I machine countersink the sub spar assembly?
Answer: Make sure to use the 1/8" (#30) 120 degree countersink. Practice on scrap aluminum first. Hold the stop with one hand against the aluminum to keep the stop from spinning, while drilling with the other hand. One author recommends using a lower speed and higher pressure than drilling, not to exceed 2500 rpm. Whatever combination of speed and pressure used, the goal is to avoid chattering which will result in an uneven surface and irregular depth. A drop of machine oil may extend the life of the countersink bit. It is important to maintain the angle once you start drilling and avoid "wobbling." If the drill is not perpendicular to the hole, it will appear eccentric. Just clear the loose aluminum, reset the angle and drill again. Once the depth was set on the practice aluminum, I took a 2X4 and essentially match drilled three holes into the 2X4 near the center. I then enlarged the center hole in the 2X4. I clamped the 2X4 to the EAA table and cleco-ed the sub spar assembly to the 2X4. I then countersunk the hole over the enlarged hole in the 2X4. I did need to drill a few "sets" of holes to accomodate the variable spacing in the flanges and the ends of the flanges. Be aware that both the lock nut AND/OR the plastic stop can become loose and contribute to irregular depths.

Dumb ? #24) How do I generate enough pressure to repeatedly squeeze AN470 AD 4-4 rivets?
Answer: After hand squeezing a few of these rivets, my arms started to fatigue. I found it a lot easier to start the rivets using hand strength and then complete the task by resting the straight arm of the rivet squeezer on a wooden stool, using body weight to accomplish final rivet compression.
 
Last edited:
Well I have another dumb ? When squeezing the AN470 AD4-4 rivets the only way I can get an adequate shop head width of 1.5 times the rivet diameter is to squeeze the rivet so that the height is less than .5 times the rivet diameter. Is this acceptable technique?

One text I have says the shop head height should be about .5D, but the shop head diameter should have a minimum of 1.5D.
 
Gandalf said:
One text I have says the shop head height should be about .5D, but the shop head diameter should have a minimum of 1.5D.
Click to expand...

Ideally, yes, .5D/1.5D. In reality, there are margins to this. See the riveting mil spec

http://www.auf.asn.au/scratchbuilder/MIL-R-47196A.pdf
(there are other places to obtain the document... just do a google search for mil spec riveting).

The above document will give you the min/max of heights and diameters. That's what I used.
 
Actually a large contributor to chattering of a countersink is the pilot reaching the bottom of the hole. This seems especially true on spars. I know a lot of builders, me included used a shim on the bottom of the flange to allow the pilot to stay stable in the hole. Once the aluminum thins as the cutter removes the material, the pilot will wobble and round out the hole ever so slightly and then the chattering and flat edge countersinks appear.
 
Try a longer rivet

Gandalf said:
Well I have another dumb ? When squeezing the AN470 AD4-4 rivets the only way I can get an adequate shop head width of 1.5 times the rivet diameter is to squeeze the rivet so that the height is less than .5 times the rivet diameter. Is this acceptable technique?

One text I have says the shop head height should be about .5D, but the shop head diameter should have a minimum of 1.5D.
Click to expand...

Would it help to use a longer rivet? Say an AD4-4.5? How much of the rivet is sticking through before squeezing?
 
flytoboat said:
Would it help to use a longer rivet? Say an AD4-4.5? How much of the rivet is sticking through before squeezing?
Click to expand...

FlyToBoat.. Good point. The rivet protrudes only 1D, not 1.5D which explains the short head. I am just supposing that Vans choose a compromise rivet size, but it would have been useful to know that the rivet was on the short side before trying to make a 1.5D shop head!

Jeff
 
Rick S. said:
Actually a large contributor to chattering of a countersink is the pilot reaching the bottom of the hole. This seems especially true on spars. I know a lot of builders, me included used a shim on the bottom of the flange to allow the pilot to stay stable in the hole. Once the aluminum thins as the cutter removes the material, the pilot will wobble and round out the hole ever so slightly and then the chattering and flat edge countersinks appear.
Click to expand...

Rick... A nice point. I will add that to the answer. I noticed that phenomenon when I practiced on thinner metal, but for whatever reason, I did not run into that problem on the spars.

More of my really dumb ? and answers from:

http://www.vansairforce.com/communit...t=33181&page=2

Dumb ? #23) How do I machine countersink the sub spar assembly?
Answer: Make sure to use the 1/8" (#30) 120 degree countersink. Practice on scrap aluminum first. Hold the stop with one hand against the aluminum to keep the stop from spinning, while drilling with the other hand. One author recommends using a lower speed and higher pressure than drilling, not to exceed 2500 rpm. Whatever combination of speed and pressure used, the goal is to avoid chattering which will result in an uneven surface and irregular depth. If the pilot reaches the back wall of the aluminum, the bit can chatter. If the pilot reaches the back wall of the spar, a shim can be used behind the spar to center the pilot. A drop of machine oil may extend the life of the countersink bit. It is important to maintain the angle once you start drilling and avoid "wobbling." If the drill is not perpendicular to the hole, it will appear eccentric. Just clear the loose aluminum, reset the angle and drill again. Once the depth was set on the practice aluminum, I took a 2X4 and essentially match drilled three holes into the 2X4 near the center. I then enlarged the center hole in the 2X4. I clamped the 2X4 to the EAA table and cleco-ed the sub spar assembly to the 2X4. I then countersunk the hole over the enlarged hole in the 2X4. I did need to drill a few "sets" of holes to accomodate the variable spacing in the flanges and the ends of the flanges. Be aware that both the lock nut AND/OR the plastic stop can become loose and contribute to irregular depths.

Dumb ? #24) How do I generate enough pressure to repeatedly squeeze AN470 AD 4-4 rivets?
Answer: After hand squeezing a few of these rivets, my arms started to fatigue. I found it a lot easier to start the rivets using hand strength and then complete the task by resting the straight arm of the rivet squeezer on a wooden stool, using body weight to accomplish final rivet compression. Be aware of the extra compression generated by this technique, especially if the rivet should start to bend.

Dumb ? #25) I squeezed the AN470 AD4-4 rivet on the stub spar and hinges to 1.5D, but the height is less than .5D. What's up?
Answer: The AN470 AD4-4 may be a bit short for this application, so aim for a shop head diameter between 0.163 inches and slightly less than 1.5 times the rivet diameter. That should result in a shop head depth between 0.05 and 0.07 inches.
 
Last edited:
More of my really dumb ? and answers from:

http://www.vansairforce.com/communit...t=33181&page=2

Dumb ? #23) How do I machine countersink the sub spar assembly?
Answer: Make sure to use the 1/8" (#30) 120 degree countersink. Practice on scrap aluminum first. Hold the stop with one hand against the aluminum to keep the stop from spinning, while drilling with the other hand. One author recommends using a lower speed and higher pressure than drilling, not to exceed 2500 rpm. Whatever combination of speed and pressure used, the goal is to avoid chattering which will result in an uneven surface and irregular depth. If the pilot reaches the back wall of the aluminum, the bit can chatter. If the pilot reaches the back wall of the spar, a shim can be used behind the spar to center the pilot. A drop of machine oil may extend the life of the countersink bit. It is important to maintain the angle once you start drilling and avoid "wobbling." If the drill is not perpendicular to the hole, it will appear eccentric. Just clear the loose aluminum, reset the angle and drill again. Once the depth was set on the practice aluminum, I took a 2X4 and essentially match drilled three holes into the 2X4 near the center. I then enlarged the center hole in the 2X4. I clamped the 2X4 to the EAA table and cleco-ed the sub spar assembly to the 2X4. I then countersunk the hole over the enlarged hole in the 2X4. I did need to drill a few "sets" of holes to accomodate the variable spacing in the flanges and the ends of the flanges. Be aware that both the lock nut AND/OR the plastic stop can become loose and contribute to irregular depths.

Dumb ? #24) How do I generate enough pressure to repeatedly squeeze AN470 AD 4-4 rivets?
Answer: After hand squeezing a few of these rivets, my arms started to fatigue. I found it a lot easier to start the rivets using hand strength and then complete the task by resting the straight arm of the rivet squeezer on a wooden stool, using body weight to accomplish final rivet compression. Be aware of the extra compression generated by this technique, especially if the rivet should start to bend.

Dumb ? #25) I squeezed the AN470 AD4-4 rivet on the stub spar and hinges to 1.5D, but the height is less than .5D. What's up?
Answer: The AN470 AD4-4 may be a bit short for this application, so aim for a shop head diameter between 0.163 inches and slightly less than 1.5 times the rivet diameter. That should result in a shop head depth between 0.05 and 0.07 inches.

Dumb ? #26) The W-1212 Hinge Assembly calls for two AN426AD4-6 flush rivets. If I machine countersink both sides of the assembly for a flush machine head, the shop head is proud. Is this going to interfere with movement of the flaperon?
Answer: Van's prefers that the shop head is flush, but there is some clearance. The shop head can be filed down.

Dumb ? #27) I don't see any instructions on attaching the flaperon to the wing in Section 18. Am I missing a Section 19?
Answer: Nope. The instructions for attaching the flaperons and the needed hardware such as the AN3 bolt are not included in the wing kit.

Dumb ? #28) Is there a directionality when fluting the nose ribs?
Answer: YES. The indentations should point inward, away from the skin surface.

Dumb ? #29) How many holes need to be manually dimpled in the leading edge of the inboard wing skin?
Answer: Three. One in one place and two in one place for a total of two places. Go figure :)

Dumb ? #30) How can I bend the lower edge of the wing doubler?
Answer: I used an customized edge rolling tool. I moved the rollers of the Avery edge roller closer together to close the gap and, as suggested by "Butch", I removed two small washers under the rollers to narrow the width of the rolled edge. Finally, I used the tool at a slight angle so that only one edge of the tool rubbed on the sheet metal, keeping the rollers off the dimples. I only rolled the edge enough for cosmetic purposes, not enough to make full contact with the underlying skin.

Dumb ? #31) How do I get the spar rivets to go into the wing doubler?
Answer: With the wing doubler "free", where possible I inserted any difficult spar rivets into the wing doubler and clecoed the remaining spar rivet holes. Only then did I clecoe the remaining wing doubler to the wing. This requires some ingenuity in getting the inferior row of clecoes into the leading edge of the wing doubler.
 
Last edited:
While trying to rivet the W1204H wing tip trailing edge, I discovered that two of the rivet shop heads collided preventing the rivets from properly seating. On one rivet I was able to use a rivet gauge to gently lift the inner surface, providing enough offset for the rivet heads to clear. On the second rivet, I angled the rivet so that it was set on one side. I then slowly HAND squeezed the rivet until it collapsed, allowing the rivet to seat flush with the surface. Using the hand rivet gun was a last ditch effort born out of necessity!

More of my really dumb ? and answers from:

http://www.vansairforce.com/communit...t=33181&page=2

Dumb ? #23) How do I machine countersink the sub spar assembly?
Answer: Make sure to use the 1/8" (#30) 120 degree countersink. Practice on scrap aluminum first. Hold the stop with one hand against the aluminum to keep the stop from spinning, while drilling with the other hand. One author recommends using a lower speed and higher pressure than drilling, not to exceed 2500 rpm. Whatever combination of speed and pressure used, the goal is to avoid chattering which will result in an uneven surface and irregular depth. If the pilot reaches the back wall of the aluminum, the bit can chatter. If the pilot reaches the back wall of the spar, a shim can be used behind the spar to center the pilot. A drop of machine oil may extend the life of the countersink bit. It is important to maintain the angle once you start drilling and avoid "wobbling." If the drill is not perpendicular to the hole, it will appear eccentric. Just clear the loose aluminum, reset the angle and drill again. Once the depth was set on the practice aluminum, I took a 2X4 and essentially match drilled three holes into the 2X4 near the center. I then enlarged the center hole in the 2X4. I clamped the 2X4 to the EAA table and cleco-ed the sub spar assembly to the 2X4. I then countersunk the hole over the enlarged hole in the 2X4. I did need to drill a few "sets" of holes to accomodate the variable spacing in the flanges and the ends of the flanges. Be aware that both the lock nut AND/OR the plastic stop can become loose and contribute to irregular depths.

Dumb ? #24) How do I generate enough pressure to repeatedly squeeze AN470 AD 4-4 rivets?
Answer: After hand squeezing a few of these rivets, my arms started to fatigue. I found it a lot easier to start the rivets using hand strength and then complete the task by resting the straight arm of the rivet squeezer on a wooden stool, using body weight to accomplish final rivet compression. Be aware of the extra compression generated by this technique, especially if the rivet should start to bend.

Dumb ? #25) I squeezed the AN470 AD4-4 rivet on the stub spar and hinges to 1.5D, but the height is less than .5D. What's up?
Answer: The AN470 AD4-4 may be a bit short for this application, so aim for a shop head diameter between 0.163 inches and slightly less than 1.5 times the rivet diameter. That should result in a shop head depth between 0.05 and 0.07 inches.

Dumb ? #26) The W-1212 Hinge Assembly calls for two AN426AD4-6 flush rivets. If I machine countersink both sides of the assembly for a flush machine head, the shop head is proud. Is this going to interfere with movement of the flaperon?
Answer: Van's prefers that the shop head is flush, but there is some clearance. The shop head can be filed down.

Dumb ? #27) I don't see any instructions on attaching the flaperon to the wing in Section 18. Am I missing a Section 19?
Answer: Nope. The instructions for attaching the flaperons and the needed hardware such as the AN3 bolt are not included in the wing kit.

Dumb ? #28) Is there a directionality when fluting the nose ribs?
Answer: YES. The indentations should point inward, away from the skin surface.

Dumb ? #29) How many holes need to be manually dimpled in the leading edge of the inboard wing skin?
Answer: Three. One in one place and two in one place for a total of two places. Go figure

Dumb ? #30) How can I bend the lower edge of the wing doubler?
Answer: I used an customized edge rolling tool. I moved the rollers of the Avery edge roller closer together to close the gap and, as suggested by "Butch", I removed two small washers under the rollers to narrow the width of the rolled edge. Finally, I used the tool at a slight angle so that only one edge of the tool rubbed on the sheet metal, keeping the rollers off the dimples. I only rolled the edge enough for cosmetic purposes, not enough to make full contact with the underlying skin.

Dumb ? #31) How do I get the spar rivets to go into the wing doubler?
Answer: With the wing doubler "free", where possible I inserted any difficult spar rivets into the wing doubler and clecoed the remaining spar rivet holes. Only then did I clecoe the remaining wing doubler to the wing. This requires some ingenuity in getting the inferior row of clecoes into the leading edge of the wing doubler.

Dumb ? #32) Twice, when trying to rivet the W1204H wing tip trailing edge to the wing, the rivet shop head collides with an existing pulled rivet shop head. This prevents the manufactured rivet head from seating fully. How do I get these two rivets to seat fully?
Answer: On one rivet I was able to gently lift the inner surface with the round side of a rivet gauge to provide clearance. Your experience may vary. On a second rivet, I used a hand rivet gun. I angled the rivet so that one side of the manufactured head was seated against the surface. I then slowly pulled the rivet. As the shop head was slowly pulled in I was able to slowing bring the rivet perpendicular and flush to the surface.
 
You must log in or register to reply here.
Back
Top