I decided to finish up the elevators this weekend. I updrilled all of the holes to final size and also cleaned up the overlap on the elevator root assembly. I had cut the elevator skins according to the size and angles required, but the control horn assembly that was provided by Sonex caused the skins to overlap by almost 5-7mm, with the overlap being more pronounced near the tips. I filed down the excess so that the elevator skins were flush with the edge of the root assembly ribs.
All that remains now is to debur, polish and prime the ribs and to rivet the bottom portion of the elevator. The top portion will have to remain cleco-ed until the MD-RA inspection is complete.
I worked on polishing of the rear spar for the horizontal stabilizer and deburring of the spar channels. The rear spar had a lot of relatively deep cuts and stratches, presumably made while the spar was being fabricated. I used red Scotchbrite pads to smooth the surface and then used grey Scotchbrite pads to further polish it. I then cleaned with Paint Thinner and then sprayed with self-etching primer. I cleco-ed everything back together and riveted the whole rear spar assembly.
I worked on installing the left hinge on the horizontal stabilizer today. I again used the elevator as a guide and added the end-stop to ensure everything is flush with the edge of the stabilizer.
I did not have a piece of hinge left that spanned the entire required length so I made it out of two pieces instead. I had previously confirmed with Kerry at Sonex that this was acceptable, and he indicated that as long as the hinge pin spanned the entire length, it wasn't a problem.
I positioned the elevator with the hinge pieces in place and drilled and cleco-ed everything together.
I worked on installing the right hinge on the horizontal stabilizer assembly today. I wanted to use the elevators as a guide to determine the correct position of the hinge, but the elevators were still all cleco-ed and these clecos interfered with the installation, so I removed them and used #4 stainless steel screws to temporarily fasten the hinge half on the elevator. I did this for both the left and right elevators. I marked up the other hinge half using a ruler and installed the hinge onto the elevator using the hinge pin. I then added an end-stop using a piece of channel stock to allow me to ensure that the elevator is installed flush with the edge of the horizontal stabilizer. I then positioned the elevtor in place and lined up the hinge to the correct position and drilled and cleco-ed everything in place.
There is about 1-2mm of play laterally with every hinge, and when I installed the right elevator, I had it pushed all the way to left. This means that the elevator can actually move 1-2mm to the right and scrape the end-stop, so I moved the hinge down 1-2mm to avoid this. I wanted to make sure that when the fiberglass tip is in place, the required minimum gap is maintained even if the elevator slides latterally a little.
I noticed this problem after drilling the first hole, causing it to be off a little. However, once up-drilled, the issue is no longer there. Hence the 1/8" (copper) cleco in the corner of the first picture below.
A piece of channel stock was used as an end-stop for the elevator.
Clecos on the hinge temporarily replaced with #4 stainless steel washer and screws.
I cleco-ed the entire horizontal stabilizer assembly together and marked the centre line on each of the ribs as well as the the forward spar. Throughout the process, I used a heavy piece of metal from my bending brake to hold down the ribs and assembly while drilling and cleco-ing everything in place. I routinely checked to make sure that the ribs were perpendicular with the table surface using a straight edge. I proceeded to lay the skins over the stablizer assembly and lined up the pre-drilled holes in the skins with the centre line on the ribs and forward spar assembly. With the exception of the the longest rib, all the holes lined up reasonably well with the skin.
The longest rib did not line up correctly. It turns out that the attachment bracket position was a few millimeters off and this caused the angle of the rib to not match up. I left this issue for now and proceeded to drill and cleco the skins in place. I did this for the left and right side before turning the whole assembly over and drilling and cleco-ing the other side.
I up-drilled everything with the exception of the tips and the edge where the hinge will be positioned.
I contacted Kerry at Sonex concerning the tight bend angles for my main spar and forward spar channels. He indicated that they were indeed tight but that there will be very little load at the tips and therefore these were not a concern. He suggested I use the hand seamer next time for these bends. I proceeded to fabricating the ribs and brackets for the horizontal stablizer.
I didn't get a chance to clean up my 8ft bench and remove the drill press and grinder that I had mounted to it, so I decided to work on the horizontal stablizer instead of the elevators.
The first hour or so was spent making the main spar channel and forward spar channel parts from channel stock. Each end of the channel stock had a flange that needed to be bent either 90° or 22°. I used a wooden block that I cut to size that fit the channel and then tapered the block so that I could easily make the bend to 90° (which requires you to over bend it by about 5-10° - hence the tapering).
I rounded out the tip of the slanted end of the block so that I would have the proper bend radius. It turns out that wood may have compressed at the tip when I made the bend and I actually ended up with a bend angle that is much less than the 1.6mm bend radius that the plans call for. The parts with the 22° bend don't show any significant material compression near the bend, but the 90° parts hint of material compression at the bend.
I proceeded lining up the channels on the main spar and confirmed the overall length before drilling and cleco-ing everything in place.
I worked on drilling the left elevator assembly today. I first drilled the pilot holes in the hinge itself and then fitted the ribs in place. I noticed that one of the rib's edges was taller than the other on the opposite side, and as I had always used the open edge of the rib as reference for marking up the centre line, this would cause a problem when trying to fit the rib. It would have likely required the rib to be twisted to line up with the holes I had drilled in the top and bottom of the elevator skins. Luckily, I noticed it in time and used the closed edge as a reference to determine the centre line instead. I have made a note to do this from now on. It will likely save me a lot of grief later on.
Once the ribs were in place, I removed the clecos from the bottom and laid the whole elevator assembly flat on the workbench. I then used my wood frame again to keep the elevator down while lining up the hinge. I again used a 0.060" spacer to line up the centre hole on the hinge and then worked my way outward to each side drilling and cleco-ing while alternating left and right. The drilling is a lot easier when there is a cleco in the adjacent hole, so I don't need to put a piece of wood behind it to prevent the skin from buckling while drilling.
Now that both the left and right elevators are done, the next step is to line them up and attach the control horn. This will require that I use my 8ft workbench.
The pre-formed parts from Sonex are nice, but they are not perfect. One side is taller than the other. You need to always measure the centre line from the closed edge of the part.
I finally had a chance to work on the right elevator. I received the SNX-Z03-01 control stock a couple of weeks ago that I needed to redo the right elevator. Although the control stock is about $75 from Sonex, by the time it ends up on my door step, and shipping/handling/brokerage/taxes are added on, it turns out to cost over $250. Hard to believe for a piece of sheetmetal. I'm going to have to check the export documentation to make sure that Sonex is submitting the right paperwork and indicating the correct HS classification. Anyway, lesson learned: re-read the plans and check measurements before drilling!
I used the Dremmel Saw-Max again to make the initial cuts and then used the Vixen file and Scotch brite wheel to get me to the line. I marked the drill lines in the centre of the elevator and the edge and drilled the pilot holes. I made sure that all the holes lined up with the centre line on the ribs without requiring the ribs to be twisted, as this may warp the elevator once everything is riveted in place. Once the ribs were in place and one side cleco-ed, I laid the elevator flat on the bench and added a wood frame -made from 2x4s- to ensure that the elevator remained flush and not twisted while drilling the hinge. I used a piece of 0.060" aluminum as a spacer (the plans call for a 0.057" spacing, but I didn't have this available). I then lined up the appropriate hole on the hinge with the centre line on the elevator and drilled the first hole. I then worked me way out to each side, alternating left-and-right. After the hinge was all drilled and cleco-ed, I drilled the additional 6 holes in the ribs on the short edge of the elevator.
I worked on drilling the pilot holes for the ribs and hinge on the right elevator. This didn't go as smoothly as I had hoped. The top of the hinge had to be positioned 1.45mm (0.057") below the top of the elevator skin, but I had positioned it 1.45mm above it. The hinge is therefore positioned too high. This does not appear to be salvageable so I will have to order another piece of SNX-Z03-01 control stock and redo the whole right elevator. I have a feeling this won't be the last time I have to redo a part.
I got tied up with a project for work so I didn't get as much building time in over the past few weeks. Thankfully, the project is wrapping up so I will be able to spend more time in the coming weeks.
I worked on the cutting the left and right elevators to size. I've started using a wood-working iron to cut the plastic protective covering. I had been using a utility knife, but it always left some scratches on the metal skin which then have to be polished back out later. The iron worked well and gave nice and clean cuts of the material without any scratches.
I started by marking up the skins with all the cut lines. I used the finished elevator root assembly to confirm the orientation before cutting. It's easy to make a mistake here and make the angled cut in the wrong direction. I used the Dremel Saw-Max to make the initial cut. It worked reasonably well, but it does seem to heat up the material quite a bit, as the protective covering turned brown close to the cut line. I used a Scotch-brite wheel to take most of the excess material off and then used a vixen file to get me to the cut line.
Next, I will have to mark and drill the pilot holes for the end ribs, center ribs and root assembly.
I fitted the fiberglass tip to the vertical tail assembly. I wanted to be able to hang the rudder so I could check clearances, but the rudder is only partially riveted (for inspection), so I used a piece of sheet metal on a hinge to confirm the distances.
A lot of measuring and double-checking had to be done in order to ensure a good fit. I used a straight edge to ensure that the tip was centered on the tail and that it wasn't angled incorrectly. I drilled pilot holes and up-drilled to #30 and cleco-ed.
I'm ready to rivet one side of the vertical stabilizer, but I'm waiting on feedback from Kerry at Sonex to find out if it is acceptable to have the skin under tension. There is a significant amount of spring left in the skins and I'm concerned that riveting the skins under tension will cause issues.
I riveted the forward spar and main spar assemblies. I also installed the AN3 bolts. The thread on the bolts did not extend far enough down, requiring a total of 3 washers instead of the 2 the plans call for. I did not get a chance to complete the riveting of the vertical stablizer.
I did more work on the vertical stabilizer today. I spent time fitting the skins and making sure that all the holes lined up on the center of the various ribs. I then pilot drilled all the holes and cleco-ed everything together and then up-drilled to #30.
The SNX-T12-10 clip that I had previously fabricated did not appear to cause the tip rib to be positioned correctly for the holes in the skin. I checked the measurements of the clip and it was all correct. If I used the clip, the holes would be too close to the inside edge of the rib. I contemplated putting the clip inside the rib instead of on top of the rib. This would have moved the rib up and lined up the holes with the center of the rib better. However, this is not standard aircraft construction practice, so I decided to fabricate a new clip that had a longer flange so that I could push the clip up more.
I attached the rudder hinge and drilled all the pilot holes. I then up-drilled to #30 and cleco-ed everything togeher. Once I had updrilled everything, I took everything apart and deburred, cleaned and primed all the parts. Next time, I'm going to rivet everything together.
Up-drilled to #30
Attached the hinge for the rudder and drilled the pilot holes.
The flange on the SNX-T12-10 clip wasn't long enough. A new clip allowed me to make a perfect fit for the tip rib.
Drilled the pilot holes in the skins and ribs
The entire vertical tail is disassambled and deburred, cleaned and primed.
I worked on fitting of the vertical stablizer assembly and skins. I laid out the whole stablizer on a flat surface and then clamped everything together. I then drilled all the holes for the various attachment clips. I have not yet drilled the SNX-T10-04 (tip rib), because I want to make sure that the holes in the skin are going to line up with the forward spar assmebly and if I drilled the tip rib and fastened it, it would make lining things up more difficult.
I was surprised how well overall the holes lined up with the center lines I had drawn on the various ribs. I'm going to have to figure out what I'm going to do with the 4 bad holes I drilled in the main spar assembly before I go any further.
I contacted Kerry at Sonex and provided him with a picture of the problem. He indicated "...the only thing we would ask you to do is add one additional rivet between each of the errant hole locations. Even that is most likely unneeded but it is insurance against the unlikely possibility of those holes tearing out.". In other words, a straightforwrd fix and I don't have to redo the part. Excellent!
I worked on the SNX-T09-01 main spar assembly and the SNX-T09-02 forward spar assembly for the vertical stablizer. This required a lot of measuring and checking because I wanted to make sure that the pre-drilled skins were going to fit without too much trouble.
I needed to drill the holes for the AN3 bolts, but could not find any documentation on what the correct drill size is for this. I find it a bit perplexing that there is no universally accepted standard for this. I found a lot of different ways people in various groups suggested on doing this, some say start with #13 and then drill with #12 and then use a #12 reamer. I contacted Kerry at Sonex and he suggested to either use #11 or 3/16" bit. I did not have any #11 drill bits and checked with Aircraft Spruce and they didn't appear to have any either, so I settled on 3/16". I drilled a test hole and the fit was reasonable. However, when drilling the actual main spar, I found that there was way too much slop. I will have to get a #11 and #12 and reamer and see if that provides better results.
The plans indicated the location of the rudder hinge, which I carefully located and then fastened to the main spar, with the eye of the hinge centered on the edge of the spar. After I had it all lined up, I went ahead without thinking and started to drill the holes so I could cleco the hinge. While I was doing this, I realized that the skins were already pre-drilled and unless I had located the holes perfectly, they weren't going to line up!
I quickly assembled the vertical stablizer and wrapped the skin around only to discover that the 4 holes I had drilled were exactly on the center of the edge of the channel, whereas the skins had the holes located more to the right edge of the channel. I'm not yet sure if I'm going to have to scrap the SNX-T12-03 upper spar channel piece, or if I can salvage it. It looks like the distance between the bad hole and the correct hole is approx. 5.4mm. I believe the minimum edge clearance is supposed to be 6.4mm, so I may have to scrap this piece.
I fabricated the SNX-T12-10 clip from a scrap piece of SNX-Z03-02 channel stock. I was supposed to have a 12" piece of SNX-Z02-03 angle stock in my kit to make that part, but it was missing from my kit. I contacted Sonex to find out if there were any issues making it from 0.032" instead of 0.025" and Kerry Fores indicated it was not an issue.
I worked on fabricating more parts for the vertical stabilizer today. I fabricated SNX-T12-03, 04, 08 and 09. The SNX-T12-09 part had to be fabricated from 0.060" aluminum sheet. The bend on the part is 65° and the bend radius was 3.2mm. I used the extension rod that came with my deburring tool which had a diameter of 6.2mm, close enough to give me the proper bend. I used my bending brake with the rod secured as indicated in the picture below.
I also wanted to fabricate SNX-T12-10, but it calls for SNX-Z02-03 angle stock, which I don't appear to have. I believe the angle stock is 0.032", so I can probably make it from scrap SNX-Z03-02 channel stock.
I completed the fabrication of SNX-T10-02 today. This completes all the fabrication that is necessary for drawing SNX-T10. It took me two tries to properly fabricate this part. On the first try, I bent one of the flanges at the wrong location and on my second try I scratched up the part too severly to be usable. I'm going to have to purchase some additional SNX-Z03-04 channel stock.
Used a bending brake with a form block to make the bends.
I traced part of the drawing onto a piece of paper and then cut it out to get the right bend angle.
All parts for SNX-T10 are all done and ready to be assembled.
I worked on the design of the power conditioning unit today. The power conditioning unit takes input power from the onboard alternator and regulator and provides the necessary voltages for use by the MCU and sensors. A total of 3 different voltages will need to be provided: +12V, +5V and +3.3V, with a total combined power output of approximately 36W. This is just a preliminary design goal, as I have not finalized the EFIS design yet.
For the power conditioning unit, I chose a typical SEPIC converter design because of the need to be able to handle both input voltages well below the minimum desired output voltage, as well as above the desired output voltage. Although it is more likely that a failure in the regulator will cause an overvoltage condition (e.g. 16-18V), the possibility does exist that a partial regulator failure could cause a significant drop in output voltage (8-10V).
The power conditioning unit must accept this wide input voltage range and continue to produce clean +12V, +5V and +3.3V voltages to the EFIS. I used Linear Technology's online web tools to determine the best possible controller chips for the task. I could have started with National Semiconductor, but I've had good luck in the past with Linear so I started there. There were a number of chips that matched my input range and current criteria. I then cross-referenced these results with DigiKey to ensure that the chip was stocked and readily available.
I settled on the LT3759. This is an MSOP package chip and available in the industrial temperature range (-40°C to +125°C). This is important, as I may decide to have the MCU firewall-forward, as it will be easier to connect the thermocouples and other sensors this way.
I started with the reference design for the LT3759 and then made changes to accomodate the input range as well as the line conditioning and slow start delay. I used the SPICE circuit emulator from Linear Technologies called LTSPICE to do the circuit analysis. I primarily used their tool because it had a SPICE model for the LT3759 controller.
I still have an issue with the voltage spiking to +30V before steady-state is reached, but I think this is because I'm not giving SPICE enough time to calculate the circuit's dampening factors, so it's making incorrect assumptions. (I have since determined that the issue was because I had used an ideal voltage source. Once I specified the internal resistance of approx. 20 milli Ohms and parasitic capacitance typical of a lead-acid battery, the voltage spike was greatly diminshed). I'm only interested in the steady-state, and from that point, the results look good.
In the graph below, you can see the performance of the circuit. The blue line represents the input voltage from the alternator/regulator. I purposely set this up in the simulation as a 7V p-p sinusoid with a 10V DC component. This causes an input voltage swing from 3V all the way to 17V.
The output of the SEPIC controller is the green line. You can see it is fairly steady at 12V regardless of the input voltage. The noise is approx. 400mV p-p at a frequency of 300kHz. I'm not going to bother filtering this any further, because I'm going to have the controller feed traditional regulators for the +5V and +3.3V.
The output current is the red line. It is simply the output from the +5V regulator into a 4.8 Ohm load.
SPICE Circuit Simulation - Blue - Input Voltage; Green - converter output; Light Blue - 5V Regulator output; Red: Load current
Preliminary Power Conditioning Unit for the EFIS
Revised Power Conditioner with +12V, +5 and +3.3V outputs
I worked on the vertical Stabilizer today and fabricated the ribs out of channel stock. I also cut the piano hingest to size. For the ribs, I used a form block the width of the channel to do the bending. I messed up on SNX-T10-02, so I just cut it smaller and made SNX-T10-01 out of it. Next time, I'll pay better attention to make sure I'm bending straight.
I completed the rudder today. This involved deburring the edges and the #30 holes of the ribs as well as skins, and of course, cleaning and priming the parts. The skins were primed where it comes into contact with the ribs.
I riveted the long side of the rudder, so it would still be easy to open up the skins for the pre-cover inspection. This is required for Canadian amateur built aircraft (click here for details). The other half of the rudder will remain cleco-ed until the pre-cover inspection has been completed.
The rivets on the rudder control horn were tricky. There were 4 rivets that had interference from the adjacent rivets in the rib. I checked the plans and it appears that this is by design. It would have been better if the top holes were slightly offset so this wouldn't have been an issue. I used a hand riveter to initially pull the rivet until I could push the head flush with the skin, after that, I pulled the rivet with the pneumatic riveter.
Deburred and cleaned the rudder skins and primed the parts of the skin that come in contact with the ribs.
Ribs deburred, sanded and cleaned with alcohol and then primed.
The rivet won't seat all the way because of interference from the adjacent rivet.
I completed the installation of the rudder hinge and the rudder control horn. The hinge installation was a little bit tedious because the supplied piano hinge was bent for shipment causing a wave pattern along the flat edge of the hinge. I put the flat portion of the hinge between two metal rulers and squeezed it with my vice to make it as flat as possible.
I used a piece of 0.060" sheet metal as a spacer for the hinge because that is all I had available. This is slightly larger than the 0.057" that the plans call for, but I don't think it's going to matter.I used a wooden block behind the skin to put counter pressure for the drill. I first drilled the edges then the centre and then alternated between left and right outer edge until all holes were drilled.
The rudder control horn was equally tedious. I first drilled the holes in the skin as per the plans and then marked up the centre line of the flanges on the control horn and lined it up with the holes in the skin. There was a significant gap near one of the edges, but I managed to eliminate it by receeding the control horn slightly into the skin. This caused some holes to be closer to the inside edge of the control horn, but I determined that there was still enough clearance for the rivet.
Drilled all pilot holes in the rudder control horn.
I continued work on the rudder today. I made a hinge drilling jig (or guide) to help me drill the 41 holes that are required in the rudder hinge. I also cut the pre-formed rudder control stock to length and made the cut-out for the rudder control horn. I used a Dremmel Saw-Max with an aluminum oxide blade that cut the control stock as it if was butter. The cut-out was done initially with aviation snips and then with the Vixen file to clean it all up.
The ribs were marked up with a centre line on all the flanges. I then marked up on the control stock and drilled the holes as per the plans. Once the holes were drilled in the stock, I put the rib inside of the control stock and used the holes to line up the rib with the centre line that I had drawn on it. I then drilled pilot holes in the ribs with 3/32" bit and cleco-ed everything together.
The rib at the top of the rudder had to be flush with the edge of the stock. I used a metal ruler to make sure that the rib was completely flush. I then drilled the holes and cleco-ed everything together.
It was getting late, so I did not complete the drilling of the control stock or the control horn. or installing the hinge.
Hinge drilling jig
SNX-T13-07 hinge drilled and deburred.
The control horn is temporarily attached to the rudder to see how it fits.
The cut-out for the rudder control horn. The big almost vertical scratch you see was already there when I received the stock, so I'll have to polish that out once I'm done with the rudder.
I had some time during lunch today to rivet the elevator root assembly. I figured it was going to be easy and take me only about 15 minutes. Well, it took me the better part of 1.5 hours. It all went well until I couldn't get my pneumatic riveter perpendicular to the part to set the rivet because of the welded parts being in the way. I foolishly tried to pull a rivet with the head of the rivet gun on a slight angle. The rivet set with one side noticeably up instead of flush with the part. I decided that I was going to use the hand riveter for the other two adjacent rivets instead. I had practiced on a scrap piece before and believed that I could pull a good rivet. Well, the hand pulled rivets were even worse. I obviously need more practice.
I ended up drilling out the 3 bad rivets. I had to use a wrench to prevent the rivet head from spinning, but in the process, I created bite marks in the part from the jaws of the wrench. I now had to spend time polishing the scratches and straighten the flanges. I decided that I was going to try and use the pneumatic riveter again, as this seems to pull better rivets.
I decided to grind down the tip of the rivet gun so that half of the tip had a slight angle. This allowed me to put the proper force on the rivet head so that it remained flush with the part while pulling the rivet. This worked well for the first rivet, but I had to put a slight bend in the mandral of the other two rivets in order to ensure that the rivet stayed flush with the part.
I kept the same pressure (about 45 psi) as I was using before, but it took a little longer before the head snapped off. The end results looks fine. Lots of lessons learned today.
The 3 rivets that were replaced.
Finally got one side done, after replacing the 3 bad rivets.
The elevator root assembly was fairly straight forward. The only important thing to note was that the top edges of the left & right root ribs were not twisted.
One side drilled and cleco-ed.
Up-drilled to #30
Other side up-drilled and cleco-ed.
I deburred the ribs and horn assembly, then cleaned the ribs with maroon Scotchbrite and alchol then used Sherwin-Williams GBP 988 self-etching primer. I also used primer on the horn assembly, as the updrilling with #30 exposed bare metal. The final result is a lot cleaner and more uniform and consistent than the Alodine experiment.
The rudder drive horn assembly required a small part (-06) be made from angle stock. I initally clamped all the pieces together and used a metal ruler to make sure that all the flanges were aligned then drilled 3/32" pilot holes and cleco-ed everything together. I then up drilled everything to #30 and deburred and cleaned.
I wanted to experiment with Alumiprep and Alodine 1201 so I setup 3 baths, one with 25% solution of Alumiprep, another with a 33% solution of Alodine and finally a water bath for washing the parts. I scuffed the parts with some maroon Scotchbrite and then cleaned with alcohol and put it in the Alumiprep bath. I left it there for 3 minutes. There was still a significant amount of gas formation, which probably indicated that I had not done as thorough of a job removing the oxidization layer.
After the Alumiprep bath, I thoroughly washed the parts and then put them in the Alodine bath. The alodine contains chromates, which are very hazardous to health, so I wore goggles, respirator and thick rubber cloves. I waited about 3 minutes and then turned the parts over for another 3 minutes. After this, the parts were washed thoroughly and blown dry with compressed air. The result was not too impressive. The parts did not appear to be uniformly anodized. There were dark spots and very light spots. It also appeared that I could easily remove the anodization by gently rubbing it with my rubber gloves.
I had already bought 4 cans of Sherwyn-Williams GBP 988 self etching primer, I'm going to use that instead on the next part.
Two holes updrilled to #30, 14 left to go...
Not that great...
The first rivet! Approximately 10,000 left to go....
After bending the forward spar fitting, I moved on to bending the drive horn. The same dowel method was used, but this time I was able to use the big vice, which made it easy. I got close with the vice and then used a rubber mallet to get me to exactly 5°.
I thought that I would start the Sonex build with something simple: bending the forward spar fitting. This part came with the tail kit already cut to size, all that needed to be done is bend it to 35°. This proved not as straight forward as I had hoped. I initially inteded to use my Arbor Press, as Sonex suggested with the wood cut out, but I decided to use the dowel and vice method that other builders had successfully used.
When you're using the dowel method, the dowel is centered between the bend tangency lines. I managed to split my wood dowels so I ended up using 1" diameter steel pipe instead. It is important to make sure that the steel pipe extends above and below the edges of the part, so that you don't get any imprints on the part. The steel pipe tended to move around while I closed the vice, so I drilled two 1" holes about 2.5" apart in a piece of 2-by-4 and split it in half to hold my steel pipe in place.
The steel pipes also tended to deform, so I decided to use a socket wrench with a 1" OD. This ensured that the part had the proper bend radius. I ended up needing to bend almost 10° further just to end up at 35° when the part is removed from the vice.
The jaws on the larger vice were too wide for the bend angle, so I had to use my smaller drill press vice.
I built two EAA work benches according to the official plans (click here for a copy). I made one bench 8 feet long and the other the standard 5 feet. The 8 feet bench has extra re-inforcements to ensure that the table surface doesn't bow and remain completely level. I also added the adjustable feet, as my concrete floor is on an incline. I used galvanized bolts and two nuts per leg. First I used a 0.5" drill to drill a shaft 3" down in each leg and then used a 1" unibit to make the opening for the nut. I just pounded the nut in with a hammer until it was flush with the leg, and since the nut is slightly larger than 1" and the opening tapered, it fit snuggly without the need for epoxy to hold it in place.
I ended up buying a lot of tools. I strongly believe that you need the right tools for the job otherwise the build process could get more frustrating than it needs to be. You could probably do with less.
It took me a few months to turn my garage into a workshop. I had used the garage primarily as storage space so all this had to be moved to a self-storage unit down the street. I had contemplated setting up my workshop in the self-storage unit, because of the additional space and 11 foot ceiling, but the lack of available power meant that I would have to invest in a generator or tap into the emergency lighting. I read from a number of builder sites that the recommendation is to start the build in the garage, as you can spend 15 minutes here and there and still make progress. The garage was already dry-walled when we moved in, but not finished. I ended up painting the walls, ceilling and sealed and painted the concrete floor. It turned out reasonably well.
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