During the week Dan aligned the second hinge to the other angle and match drilled them. While this sounds easy is involves having all five hinge sections joined with their hinge pins in supporting the angle in the right position wile match drilling.
This Brake design uses one of the angle pieces at the bending nose for the sheet metal. That is why we bought 1/4″ thick angle, so we could get a 1/8″ radius bends. Now standard angle does not have a full radius at the end of the legs. We broke out the vixen files and filed until we got a nice bull nose. Here is a little 1/8″ radius template from a piece of scrap.
Once we liked the bend radius we located this angle and drilled holes for the clamping bolts
We had a six foot P3 stainless steel hinge to use on the 9′ brake. From the small brake on can see the middle will bow during a bend for a thicker material. We decided to place break the hinge up into sections. We put 2′ in the middle and on each side we have a 9″ space then a 1′ hinge section, another 9″ space and another 1′ section of hinge. This leave a 1″ gap from the outside edge to a hinge.
Here is Dan cutting the stainless hinge with a Dremel wheel (Always wear safety glasses when using a Dremel!! ask my Dad)
We used some stainless rivets to attach the hinges. We used the “yardstick hinge hole template” to drill the pilot holes. Stainless is a lot tougher to drill through than alumunim. Dan would spot face the hinges with teh template and I used the drill press to finish the holes. Here is four of the five hinge pieces:
Aligning the first hinge halfs with the fisrt angle wasn’t too hard. Match drilling through the 1/4″ steel angle was a pain. Dan used a older electric drill for this task.
Aligning the other angle with the hinge was more work.
Dan painted the angles and the welded up the handle from the square tubing. Dan has done some gas welding in the past and was getting back into it. I think the weld beads looked really good (for something that doesn’t have to fly).
We decided to make a David Clay bending brake for the rear spars, the ailerons and the flaps. The plans show the rear spars can be made in two peices, and joined together with a splice plate. They did this to keep one of the parts at eight feet long, perhaps to help with a sheet size of the aluminum or shipping. Anyways we decided to make a brake for the full 109″ long spars, that way we don’t have to have the splice plate.
Dan purchased three 10′ lengths of 3″x3″x1/4″ thick steel angle from a local supplier called Discount Steel, really nice outfit. We alos picked up some square tubing for the handle. He cut it to length and cleaned them up. Really dirty work. He had to clean up the shop after this. Dan primed them for painting.
Notice the box of hardware from Aircraft Spruce on the workbench
We have a friend Gary in our flying club who is building an EVO Rocket. Sweet plane, checkout the EVO website. Gary’s fuselage is just out of the pictures. It was motinating to see his plane.
The Rocket is a variation on the RV line which uses solid rivets. The Sonex spar uses solid rivets and Sonex Company reccomends using a dished out bold and big hammer. Lots of builders have done this with great results. Gary graciously offered to lend us his rivet gun for our spar. He gave us a lesson on riveting 101.
Gary the “Rivet Master” & Dan
Would you trust this guy with your spar?
One thing to note is that RVs use size 3 and 4 rivets. The Sonex Spar uses size 5. So you need a 3X or larger gun for the Sonex rivets. If you use a smaller gun I’be been told the rivets will work harden before they are properly set.
Looking at all the ribs to make and all the long cuts to do, Dan purchased an electric shear. The tool is wonderful, it eats .025 aluminum easily. There is some technique to using it, and it wastes ~1/4″ strip between the cuts. It makes life so much easier and you don’t get the scallops form the big grey hand shears.
I had ordered and received replacement crankshaft-connecting rod bearings. Dan and I took a couple hours to put the compressor back together. Dan had some STP type stuff to put in the bearings during assembly. We put the flapper plates back together, bolted it all together, filled it with oil, put the fly wheel on, and …. it works and it is much more quiet. So far so good. The worn bearings must have been rattling around.
I bought a 60 gallon Craftsman air compressor off of craigslist last fall. It has great specs, 11.5 cfm at 90 psi. It is a 220v model.
The Beast
When we went to check it out we ran it and it was loud lout loud. A real clack clack clak… You can’t talk to someone next to you. I thought this was the normal sound for large compressor and I bought it and we brought it back to the workshop. A friend who is building a Harmon Rocket has a new compressor and Dan mentioned it is really quiet compared to the beast I bought. Well I finally tore is apart and after consulting with Dan and some engine guys at work, the crankshaft bearings are scored and beat up. So I ordered a new set and we will see if that solves the problem. In the meantime I am cleaning it up from all the paint residue inside and out from the previous owner.
Interesting side note on the bearings. I could move the connecting rod back and forth on the crankshaft and wrist pin and clack against the shoulders on the crankshaft. The bearings are narrower than the width of the connecting rod and cap. But there does not seem to be any wear on the sides of the connecting rod and end cap, I assume the crankshaft would be harder than the others. I guess you would call this side play on the connecting rod.
I took some time today to pick up some carriage bolts, nuts and washers and put our rolling 4’x12′ table on level feet so it made a better platform for assembly of the horizontal stablizer. I used scrap pieces of 2×4 and 2×6 about a foot long, drilled a 7/16″ hole in the end and screwed a 3″ long 1/2″ carriage bolt into the bottom with a washer and a stop nut.
1/2″ carriage bolt with washer and stop nut screwed into 2×6 to be anchored to side of table for leveling feet (total 10 added to 4′ x 12′ table)One of 10 leveling feet for table anchored to side of table at floor and sitting on scrap 2×4 pad
We made a variation of David Clay’s brake and reduced it to 48″ (due to the available materials at the local Menard’s store). A smaller brake is nice and a little less expensive than a full 96″ version. Most of the parts needed for the plane can be bent with this small of a brake with the exception of the ailerons, flaps and rear wing spars. So, without building another brake, the alternative is to simply purchase those parts from Sonex.
The 96″ brake will cost something in the order of $140 in metal and hardware. The mark up over raw metal for the Sonex parts is not that high and so the question is whether to build a larger brake for little cost savings (not to mention the potential of making an error during the bend process and wasting material) or simply order the pre-bent aileron’s and wing spars.
The cost of the long bent parts are as follows:
$22 for 96″ spars (x 2 = $45)
~$83 for each control surface or flap longer than 48″ (4 x $83 = $332)
So, since we already have the aluminum ( yes, we purchased all the 0.025 6061-T6 at once) we would be spending more on the pre-bent parts than on the brake. We don’t need to make the decision at this point and will take a shot at bending the rudder and elevator first. If we are successful at these then I think it’s clear that we’ll want to spend the time and money to build another (larger) brake.
Our version of the David Clay angle iron brake. Not painted and only made from 3/16″ x 2″ angle iron but it works very well for 48″ or smaller bends (which is a very large percentage of the parts needed as noted earlier).
48″ Brake
Some of the vertical stablizer parts made with the brake:
Rudder frame on benchWhen building the final jig for assembly we plotted the layout from CAD and used this instead of trying to makr the table
