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I started my Bearhawk patrol project the beginning of October by making a lot of dust making all of my MDF forms. I tried a lot of different techiniques but settled on a combination of different techniques from Bearhawk (Thanks Eric and Dave), Sonex and RV builders. I did the following with my form blocks:
1) Build master full size wing jig based upon full sized rib template temporarily glued to 3/4" MDF. Cut out on bandsaw and sanded to line
2) Build master jigs for NOSE, CENTER, FALSE, AILERON and FLAP using flush trimming router bit and jig #1. All masters were adjusted to length for maximum sized sized rib accounting for spar thickness, etc. flange holes and jig pin locations were also transferred to master jigs as 1/4" holes.
3) Using master jig #2, I made a forming jig using a router and flush cutting bit. I also cut the lightening holes with a fly cutter.
4) used jigs in #3 to make cutting jig by using 9/16" washer to allow for 9/16" flange. Cut out on band saw and sanded to line. Routed out the lightening holes with a flush cutting bit. I then made a duplicate of this jig with the router to create a top and bottom cutting jig.
5) I routed on both sides of the flanging jig with 45deg chamfer bit making a slightly wider/deeper chamfer for the lightening hole so the flanged rib would fit in.
6) made a backup form for forming jig that was 1/8" smaller by using a 1/4" bearing on 1/2" flush cutting bit.
7) cut out all the blanks for all ribs using the cutting jig and a 1/2" spiral solid carbide router bit and deburred using 6" 3M wheel on grinder and 2" wheel on drill press.
8) using 45deg chamfer bit, routed a 3/8" wide chamfer on the cutting jigs. I made a left and a right form using both cutting jigs.
9) using the 20ton press, 12"x12"x2" thick polyurethane rubber mat, I pressed the flanges into the lightening holes on all of the ribs.
10) flanged all of the ribs with dead blow hammer and flow form hammer. (I never want to see that deadblow hammer again)
11) joggled all of the center ribs and aileron pocket ribs using a metal joggle block in a vise with my flow form hammer.
12) cut, bent, deburred and drilled all of the hundreds of 1/2"x1/2" rib stiffeners.
I did use the press to form all of the Aileron, flap, aileron and flap nose ribs and aileron pocket ribs flanges. The press was not strong enough to form the larger rib flanges.
Now it was time to paint. I have plans to eventually put thus Patrol on floats out in Seattle so I wanted to use an epoxy primer. Shooting the primer outside in the winter in Denver does not always work out so well. I had started building a spray booth in my basement about a year ago for woodworking so I decided to finish it for airplane parts. I built the booth in a closet under the stairs in my basement. I built a shelf and a box at the back of the booth with two furnace filters to catch most of the paint spray. I then put a toilet flange inside the box and connected it with 6" PVC pipe to a 3HP wood working dust collector motor I had. I then plumbed the output of the dust collector motor with 6" furnace pipe outside my house. The dust collector motor/fan works great because it is an explosion proof motor/fan assembly. The has enough suction to pull all of the overspray into the filters. There is almost NO smell of paint in the house. My wife almost kicked my out for smelling up the house in the past. I am VERY VERY happy with the paint booth for these small parts. The skins will have to be done outside though. I also had a full face fresh air mask from years ago but I did not have an air supply for it. They are very expensive. I bought a CPAP machine off craigs list for $25 and used that to feed the fresh air mask. Worked great. I am now also prepared if there is an ebola breakout in my area!
I also found a great deburring tool. IKEA sells an electric screwdriver for about $9. It is the perfect speed for an Avery deburring hex bit. An electric drill is too fast. It made short work of deburring all of my nose ribs for the stiffening angles. It is just the right speed is not too aggressive.
I then riveted all of the angles using a back riveting bit in my 2x gun with the rivet die for the factory head placed in a piece of 3/4"x12"x12" plate steel as a back riveting plate. Worked great. I had not done much back riveting. I had always formed the shop head with a bucking bar. How much easier this was working alone.
One last note on the paint system I used. I was originally going to use a full Acid Etch/Alodine/epoxy primer on the aluminum parts. I HATE working with alodine and figured it is already shortened my life from past use. I looked around and found a one step product called PreKote. I LOVE IT. Very easy to use. I first washed the part with dawn and a red scotch brite pad then cleaned with Prekote and another red pad. Rinsed it and let it dry. I then top coated it with AzkoNobel 2 part green epoxy primer. I really like the aviation look of green primer and this stuff is great. After 2 days of drying, it is rock hard and even MEK will not take it off. I got the 2 gallon kit from Skygeek. Nice part is it mixes 1:1 and does not need reducer.
Well next I will be prepping and priming my center ribs and all of the other ribs. I will also have to finish up all of the rib stiffeners. I will keep everyone up to date. I am still in search for a place to bend my spars locally. Anyone know anyone in the Denver area with a 8 or 10' brake?
1) Build master full size wing jig based upon full sized rib template temporarily glued to 3/4" MDF. Cut out on bandsaw and sanded to line
2) Build master jigs for NOSE, CENTER, FALSE, AILERON and FLAP using flush trimming router bit and jig #1. All masters were adjusted to length for maximum sized sized rib accounting for spar thickness, etc. flange holes and jig pin locations were also transferred to master jigs as 1/4" holes.
3) Using master jig #2, I made a forming jig using a router and flush cutting bit. I also cut the lightening holes with a fly cutter.
4) used jigs in #3 to make cutting jig by using 9/16" washer to allow for 9/16" flange. Cut out on band saw and sanded to line. Routed out the lightening holes with a flush cutting bit. I then made a duplicate of this jig with the router to create a top and bottom cutting jig.
5) I routed on both sides of the flanging jig with 45deg chamfer bit making a slightly wider/deeper chamfer for the lightening hole so the flanged rib would fit in.
6) made a backup form for forming jig that was 1/8" smaller by using a 1/4" bearing on 1/2" flush cutting bit.
7) cut out all the blanks for all ribs using the cutting jig and a 1/2" spiral solid carbide router bit and deburred using 6" 3M wheel on grinder and 2" wheel on drill press.
8) using 45deg chamfer bit, routed a 3/8" wide chamfer on the cutting jigs. I made a left and a right form using both cutting jigs.
9) using the 20ton press, 12"x12"x2" thick polyurethane rubber mat, I pressed the flanges into the lightening holes on all of the ribs.
10) flanged all of the ribs with dead blow hammer and flow form hammer. (I never want to see that deadblow hammer again)
11) joggled all of the center ribs and aileron pocket ribs using a metal joggle block in a vise with my flow form hammer.
12) cut, bent, deburred and drilled all of the hundreds of 1/2"x1/2" rib stiffeners.
I did use the press to form all of the Aileron, flap, aileron and flap nose ribs and aileron pocket ribs flanges. The press was not strong enough to form the larger rib flanges.
Now it was time to paint. I have plans to eventually put thus Patrol on floats out in Seattle so I wanted to use an epoxy primer. Shooting the primer outside in the winter in Denver does not always work out so well. I had started building a spray booth in my basement about a year ago for woodworking so I decided to finish it for airplane parts. I built the booth in a closet under the stairs in my basement. I built a shelf and a box at the back of the booth with two furnace filters to catch most of the paint spray. I then put a toilet flange inside the box and connected it with 6" PVC pipe to a 3HP wood working dust collector motor I had. I then plumbed the output of the dust collector motor with 6" furnace pipe outside my house. The dust collector motor/fan works great because it is an explosion proof motor/fan assembly. The has enough suction to pull all of the overspray into the filters. There is almost NO smell of paint in the house. My wife almost kicked my out for smelling up the house in the past. I am VERY VERY happy with the paint booth for these small parts. The skins will have to be done outside though. I also had a full face fresh air mask from years ago but I did not have an air supply for it. They are very expensive. I bought a CPAP machine off craigs list for $25 and used that to feed the fresh air mask. Worked great. I am now also prepared if there is an ebola breakout in my area!
I also found a great deburring tool. IKEA sells an electric screwdriver for about $9. It is the perfect speed for an Avery deburring hex bit. An electric drill is too fast. It made short work of deburring all of my nose ribs for the stiffening angles. It is just the right speed is not too aggressive.
I then riveted all of the angles using a back riveting bit in my 2x gun with the rivet die for the factory head placed in a piece of 3/4"x12"x12" plate steel as a back riveting plate. Worked great. I had not done much back riveting. I had always formed the shop head with a bucking bar. How much easier this was working alone.
One last note on the paint system I used. I was originally going to use a full Acid Etch/Alodine/epoxy primer on the aluminum parts. I HATE working with alodine and figured it is already shortened my life from past use. I looked around and found a one step product called PreKote. I LOVE IT. Very easy to use. I first washed the part with dawn and a red scotch brite pad then cleaned with Prekote and another red pad. Rinsed it and let it dry. I then top coated it with AzkoNobel 2 part green epoxy primer. I really like the aviation look of green primer and this stuff is great. After 2 days of drying, it is rock hard and even MEK will not take it off. I got the 2 gallon kit from Skygeek. Nice part is it mixes 1:1 and does not need reducer.
Well next I will be prepping and priming my center ribs and all of the other ribs. I will also have to finish up all of the rib stiffeners. I will keep everyone up to date. I am still in search for a place to bend my spars locally. Anyone know anyone in the Denver area with a 8 or 10' brake?
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