Construction and alignment of the wood landing gear is often said to be one of the more difficult steps in Pietenpol construction. While building my landing gear, I came up with a procedure that worked well for me. I ended up building the gear three times using this method. The first time was using pine to test the method. The second time the gear legs turned out to long because I miscalculated the deck angle I wanted. The third, and final time, the legs turned out great. While not fool proof, it is a rather simple method but you will need to take you time to make the cuts accurate.
Fist off, I built my gear legs with the fuselage upside down. Make sure its level side to side and front to back. I used the upper longeron for my leveling reference point.
At this point you should have the out side landing gear bracket attached to the fuselage. I did not drill the holes in the metal fitting for the landing gear legs until after I had the legs cut. This way I knew where to locate the holes. Also you should not have the wing strut tab welded in yet.
Next decide where you want you axel to be located back from your fire wall. For help on this see Wood Gear Placement Analysis. Also, decide how far below the lower longerons you want the axel. The is where you will establish your deck angle.
Once you know where you want the axel, build a jig to hold it in the place. Start with something like this.
Now place your axel the distance back from the firewall you want and make it perpendicular and level to the fuselage. I placed three marks on the bottom of the fuselage (half the axel diameter forward of the preferred axel location). Then I taped three plumb-bobs on the axel (draped over the front of it) to locate the distance back from the firewall. Make sure one plumb-bob is in the center of the axel and aligned dead center of the fuselage.
Now anchor the axel in place so it will not move. I used two blocks and a strap across the tubing.
Once you have your axel located back from the firewall, perpendicular and level to the fuselage, mark the location of the inside edge of both ash blocks on the axel. Use the center mark and measure outward.
I used blue tape to help the marks show up on the axel. I put the outside edge of the tape on the mark. The location of the mark will make sense later on.
Now that you have the axel located, locked in place, and the location of the ash blocks marked add two boards parallel to the axel. These need to be longer then the distance between the two ash blocks. Clamp them in place about 6-inches in front and behind the axel. Put marks on the boards and the frame so you can put them back in the same location.
Using a string attached to the tail wheel, place a square on top of the axel at the mark for the ash block. Swing the string out until it touches the square. Mark the two cross braces where the string touches them. Do this to both right and left sides. Remove the boards. Cut the boards about ? + 1/4" short of the line. This will give you some room to add shims for a precise fit. ?= the thickness of the board after the step below.
Next make a board, lets call it board B, that will span between the two cross braces. You will need to make two.
You need make one face perfectly flat and one edge 90 to this face. I used a jointer. If you don't have one see if you can find someone to do it for you. This board and its location is really a key part of the whole process so make this as flat and square as you can.
To orient this board, clamp two gear legs into the fittings installed on the fuselage, the gear legs should be touching the axel. Place the flattened outside edge of board B on the the mark for the ash block. You will note that as you swing the board B in and out the edge of the board will line up with the plane of the two gear legs. This is what you want it to look like.
You also need to angle the board down from horizontal (back end down). I used the same angle as the deck angel.
Once you have the edge of board B in the plane of the two gear legs and slopped the proper amount screw it to the two cross braces. Check to make sure board B is resting on the axel and is perpendicular to the axel. This is very important! I ended up needing shims behind board B to accomplish this. Spend some time getting this right. If you swing a string from the tail wheel you will understand why the plans say to angle the ash block towards the tail skid. It's really close to being a perfect angle.
Now that you have block B attached where it needs to be the you can start cutting the gear legs.
Began by making a marking tool with a flat side and a chisel point. Actually I used both a chisel and a piece of metal ground down for marking.
Start with marking the bottom of the rear gear leg. I took a piece of flat aluminum bar and laid it on the fuselage bottom. Then using the marking tool, keeping it flay on the bar, scratched/marked where the leg needes to be cut.
This is where you want to cut the leg. I start by cutting the flat side so I can get the long angle correct. Sneak up on the line making test cuts, adjusting the angle each time. I did it by eyeball. You can use what ever method you want. The good part about this cut, is you hopefully have enough extra leg length to practice to get it just right. Next set the saw for the compound angle.
Once you think your saw set up correctly, make a nice clean cut and test fit the leg. If all is set right it will fit nice and tight. Make sure the leg is tight against the axel and block B when you test fit. If your happy with the fit and, if your making a test set of legs to set up your saw angles, now is the time to make the cut on your spruce gear leg. One down seven more cuts to go.
On the rear gear leg bottom (which is actually the top when you turn the fuselage over) the back part of mine did not touch the fuselage because of the curve of the fuselage bottom. I do not feel this is a problem.
At this point you can use the same procedure to cut all four bottom gear legs or you can work on one leg at a time and cut the top. I worked on one leg at a time. Also, on your finished gear leg, make several reference marks so you can place the leg back in the same spot each time you cut and test fit. Remember to clamp it onto the fitting each time. I guess you could drill the holes for the bolts now if you wanted but I waited until all the legs were done. It didn't occur to me to do it any other way.
The procedure for cutting the upper angle, where the leg sits on the ash block is much the same as the lower.
Starting with the rear leg first
Make sure the leg is clamped onto the fitting and located exactly where you want it per your reference marks. Also, use a clamp to hold the gear leg against board B. You can see this clamp on the axel in the pictures below.
Now to mark the proper cut location and angles use your marking knife, I used the corner of a chisel, and hold it flat against the bottom of board B.
To finish marking hold something flat against the bottom of board B and touching the gear leg, I used the flat side of a 1-inch chisel. Now run the marking knife along the top of the straightedge to finish making the cut.
I used my dial calipers to scribe a line parallel to the the marks just made. Make sure to mark on the waste side. Using these new marks, set up your saw to make the cut. Test your cut by holding a strait edge against board B and the top of your gear leg.
If you look at the picture above, you will see I'm not quite square. To test if the other angle is correct, I used the dial calipers to measure. Once I was happy with my saw setup, I cut close but not on the the real marks.
I slowly nibbled away and test fit the leg until the top if the leg was even with the bottom of board B. Should be right on the marks but I was paranoid so I took my time.
One leg finished! Only three more to go.
Cutting the front leg is the same procedure, except you need to make the leg the same height as the back leg. Follow the same steps to cut the bottom, then cut the top slightly long again. Check with the square to make sure you 90 degrees to the face of board B.
To check the other angle put a machined piece of wood (faced and edged like board B), on top of the front leg. Using a finely graduated ruler I simply adjusted the angle on my saw until the gap on the rear leg was equal front and back.
Now, knowing the saw was set up properly, I very slowly nibbled away at the front leg. Each time testing the length until the top block sat on the rear leg. Don't be to concerned with the block sitting right on the axel as the bungee cords will adjust for some discrepancy here. Truth be told, one of mine was perfect the other you could almost slip a piece if paper under it. Also, if you look closely at the last picture, you can see the front leg needed to be longer then the board B marks. This must be due to the rear leg to not being exactly parallel to the bottom of board B. Is this a problem? No, all we are looking for here is to get the ash block supported by the two legs and the axel held in place.
Now measure the width (width at the top of the gear legs) and length needed for the Ash block and your done with one side. All you have to do is repeat the same steps for the other side.
Another suggestion. At first I was not able to cut the angle on one the rear gear leg. The it dawned on me to remove the fence form my saw. I simply mounted a temporary fence in one side and made the cut. Unfortunately, it took me longer then it should have to think of it.
Now that all the gear legs are cut and the ash blocks have been installed make a paper pattern of the outside lower gear fitting.
Cut it out and drill the holes in the fitting. Then clamp it in place and drill the holes using the method described on this page.
Now I can mark the location for the holes in the upper gear fittings (the ones on the fuselage) and drill them using the same method as above.
You will notice my fittings are different then the plans. I have the ash cross braces in the fuselage and did not want to cut through them. My choice may not be the same as yours so the next few steps wont apply but I will show them anyway as I feel it's a good example of installing fittings and drilling accurate holes.
Next I made a paper pattern of the outer-inside fitting. Using my paper pattern I cut out four outer-inside fittings and bent them to the correct angle.
Next I drilled holes to mount the outer-inner fitting to the fuselage. I drilled the fuselage holes in the fitting with the drill press and the used the block guide to mount it to the fuselage. I did not drill the gear leg holes in the fitting yet.
Clamping the un-drilled fitting in place I used the previously drilled landing gear holes as my drill guide. I used the same stepped tubing setup as before. Except this time I am using the drilled holes as a guide.
Lastly, I installed an inner fitting to tie all this together. There was no way to clamp this piece on so I used a long piece of wood to press it in place. Once again this was an un-drilled fitting.
Everything finished with perfectly aligned holes.
Unfortunately, in the pictures above, you can't tell I have the hole cut in the outer landing gear fitting for the strut tab. While the gear is still bolded onto the fittings, mark the location on the landing gear leg. This will tell you where to notch the gear leg after you weld in the strut tab.
Now is the time to weld on the strut tabs. I built a simple jig using angle iron. Clamps hold everything in the right place while welding. (Note: Under the clamps I used some scrap pieces of steel to protect the fitting. You might recognize these scraps are bad tail wheel fittings.)
After welding I bolded everything back together
I had to cut a notch into the outer-inner fitting to straddle the strut tab. I also had to bend the fitting 1/4-inch higher then the other bend. I figured I was going to have to the calculate the bend radius, and bend line, but as it turned out all I needed to do was measure up from the previous bend line the thickness of the strut tab. At this point the all the lower fittings should be done.
Now I removed the cross braces and bolted everything together.
Time to make the inside lower fitting. Start by making a paper pattern except his time make it bigger then the final dimensions.
Cut the fitting out, bend it and clamp it in place. Using the previous holes as a guide, drill holes in the inner fitting.
After the holes are drilled you can trim it to the proper dimensions based on the locations of the holes. NOTE: These may not be the dimensions on the plans. You need to trim them keeping the proper edge clearance from the holes.
Next I made the two cross braces. First I used some 1/2-inch electrical tubing to practice with and to get the final dimensions worked out. I tapered the ends using these plates and my bench vice
Then I placed the crushed end in the vice to bend downward. The the gear is tapered front to back so the bend line is not perpendicular to the tubing. I measure the angle between the axel and the ash block to get the right angle. Don't forget to add the tab for the cross cable brace wire. It goes under the cross tube.
Once you get the technique perfected with the cheap tubing, do the same thing with the expensive tubing. In the pictures below, you will see I used some scrap metal under the tube ends. I drilled holes and bolted the spacers on to hold it them in place while I drilled the holes in the landing gear legs. I had not drilled the holes for the cross brace bolts until I knew where the holes needed to be based on the cross brace length.
Now that the cross braces are done, I laid out the final shape of the inner fittings (remember I cut then larger then needed so I could do a final sizing after the holes are drilled). In the picture below you can see my final cut lines are laid out on the oversized fitting. I also made the cross brace wire fittings.
When that was done, I powder coated all the lower fittings.
Before removing the jig holding the axel in place, I fabricated the cross wire braces.
I use the Swag-It tool to crimp the sleeves. I am using stainless steel wire so your supposed to use galvanized copper sleeves not plain copper. In the picture below the you can see the difference between the sleeves, plain copper on the left.
When making the eye I got the tip to use these Split Bolts to hold the assembly while crimping the sleeve and being copper they should not damage the wire. I found them at my local hardware store in the electrical aisle. They work fantastic as a third hand!
I followed the direction and used 3 crimps. Some people like to add shrink tubing to cover the sleeve and wire tail. I didn't use it because I though it looked to modern for my 1930's airplane.
After finishing the 4 wires I removed the jig and the gear is done!
PS, If your wondering how long it took me to build the gear, look at the length of my hair in the two pictures below. Hopefully it wont take you as long.