As I mentioned at the end of my last blog post, I want to scan some of the parts into 3D digital models.
I'm making almost everything from scratch on the build, including the small tip inserts for the slats and flapperons. Normally these come with a kit and are made of either fibreglass or more recently are blown plastic molds. I could just purchase these, but Ron has originals from a 701 which shares the same sie and shape of the 750 ones. Purchasing is easy but expensive and doesn't do anything for increasing my learning. Making my own may not be much cheaper in the long run, but certainly equal or less and making my own also means I can learn some practical skills that come from 3D modelling and printing.
First step in this process is to 3D scan the original tips. Again, I could just purchase a 3D scanner and get at it, but what fun would that be?
When Microsoft brought out the XBox gaming system, they shortly after released a sensor system that can detect player movements and translate that into interactive game play on the screen. I believe this was in response to the Nintendo Wii game system which had already broke ground and was first to market with this type of player interface. Microsoft took the best of what the Wii motion sensor did with infra-red (IR) and expanded it to include camera capable of sensing colour, faces and more refined depth of field. Enter the "Kinect".
In this past decade of electronic and programming experimentation, it wasn't long until someone (much smarter than me I'm certain) said "Hey, I wonder if there is a way to hack this XBox sensor and piggyback on what Microsoft developed for other things?" One of the first uses was for robotics control - robots that could see (sense) and recognize objects. This quickly led to 3D scanning for types of objects, both for item manipulation and avoidance (is the obstacle in my way too big to move or is it of a shape I can grab/push etc.)
These type of developments often branch out to other things, including 3D printing. Think about the possibilities! Being able to 3D scan a rare car part and print a replacement for example. Scanning and printing replacement bio-mechanical pieces (heart valves). Printing materials are also evolving - industry is now printing everything from concrete to rubber to aerospace alloys.
Like 3D scanning, 3D printing has come also come to the home/hobbyist workshop - makes sense, these home hobbyist are often on the leading edge of these things, at least initially. At thankfully for less knowledgeable people like me, they often share their knowledge online - thanks YouTube and Instructables.com!
So, where to get started. I picked up an XBox 360 Kinect sensor. It is the most current one being used by 3D scanning hobbyists and has wide ranging support.
The hack of the sensor requires 3 items. A 12 Volt power adapter (bottom left and middle), the male end of a USB cable (top) and the Kinect sensor itself (cable end on the right).
Normally the XBox console gets power and sensor data directly from the Kinect. As a result (and probably because Microsoft wants to control everything) the Kinect has a proprietary plug similar but not exactly like a USB end. The third party 3D scanning software runs on a Windows computer, so that requires a USB connection. So, my hack requires replacing the proprietary XBox connector with a USB and also injecting 12 Volt into the cable to replace the XBox console power.
I found this wiring diagram in one of the online tutorial videos. In this case, the author wanted to dual-purpose his Kinect sensor for 3D scanning and maintain it for gaming use. To do so, he added a switch in his diagram - I won't be doing this, I don't intend on reusing this for XBox, so I can eliminate the switch and the XBox end shown on the left:
First step was to clip off the unneeded end of the USB cable (the phone end in the case of my sacrificial USB cable) then strip off the outer jacket of the clipped end:
Strip back the outer shielding if there is some and the inner foil shield if there is some (cheap cables don't have these, that's why they are cheap!):
Trim away the two shields, leaving the traditional white (data -), green (data +), red (5V +) and black (ground) USB wires:
Repeat the process with the Kinect cable (cut off the proprietary plug and strip/trim the shielding:
First thing I noticed once the shielding was pulled back was an extra brown wire I wasn't expecting....hmmm.... I was expecting a gray wire. Wonder if the diagram is referring to the outer shield, it's kinda gray?
A little further reading in some of the comments on the YouTube videos and some of the instructables pages I quickly discovered that Mircosoft switched to a brown wire from gray at some point. Problem solved.
I tinned the wires first after stripping of the insulation - this makes soldering them together much easier when the time comes. I also added thin wall heat-shrink tubing to each connection which once I confirm everything is working, will be shrunk to tighten everything up. Next, solder white to white, green to green, red to red.
Next, add in the 12 Volt supply lines. Positive 12 Volt from the wall adapter to the brown wire (gray in the diagram). Lastly, black wire from the USB side, black wire from the Kinect side and Negative 12 Volt from the wall adapter (hard to see in the picture sorry).
Next, connecting to a computer and powering it all up - hopefully no smoke escapes! Unfortunately, my laptop doesn't have a graphics card that is supported by the 3D software, so I'll have to wait to get my home server back up and running to test this, but should be good!
Not much I like better than wiring projects, can't wait to do more of this on the airplane.
I'll file this in tools for now and get back to it soon. Want to get the 3D scanner working so I can scan the flapperon and slat parts I mentioned above then print them. Carbon fibre anyone? :)
Happy New Year everyone!
With the Christmas holidays over, its time to get back..... WAIT!!
Failed well pump at home - replaced/repaired.
Failing clothes dryer - replaced.
Updated home network infrastructure.... started and functionally complete, but need to do more.
Check engine light on the car and new front struts installed.
Back to work... shift shuffle meaning an extra day of work to balance out the hours....yay me.
So, unfortunately the shop has taken a back seat for a couple of weeks. However, I AM BACK!
First up, finishing the centre section drilling out to A5. There is no question the number of rivets make this centre section solid:
Drilled out the rest of the elevator skin and nose skin holes to correct size:
Caitlyn came over with me to the shop on boxing day to shoot some pics of me working. Here I've taken the nose skin off the elevator to prep the outer hinge plate/pins.
The plates are made of 4130 steel, so it's important to centre punch them so the drill bit doesn't wander:
A bit of WD40 helps cool the bit, 4130 is a lot harder to drill than aluminum:
First holes drilled and plates clecoed in place - back drill to A3 then A4, then A5:
Nose skins back on, back on the bench with the stabilizer to start lining everything up, and...
.... uh-oh.... some interference between the nose skins and the centre support brackets. Apparently this is a common problem which is easily remedied by trimming the nose skin slightly and trimming the back the rudder support plate edges to clearance the nose skin as it pivots.
The fit of the hinge pivot point is still bang on - good!
Before pulling them apart again, I used a sharpie to rough out where I need to remove some aluminum:
While I had some downtime during a nightshift at work, I rigged up the trim servo and Arduino controller along with an example rocker switch. I had set this aside for several weeks but I wanted to refine my programming code a bit. This is a refurb laptop I fixed up and it took some more work getting the proper drivers for the Arduino installed amongst other things, but once I had those my new code loaded up perfectly and it looks like I've got the system nailed down to do what I want!
I brought the mock-up to the shop to show Ron but decided it would be a bit easier to demonstrate by mounting it to a board. I've added some spare LED lights to represent a cockpit indicator and a suplus limit switch to represent a momentary contact switch. I also added a really fancy post-it note flag to the arm of the servo to make it easier to see in a video.
Here is a short video describing the components of the system, my reasons for doing so and a demo of what it currently is programmed to do. Be kind, I'm no Martin Scorsese HA!
I've been thinking hard on how to bend the elevator trim tab. It's 025 thick and quite long. In addition, it has some complex tight bends that will be hard to do effectively on the bending brake, so I had to really think out an order of operations.
Like I usually do, I made up a test piece from some scrap 025 and used it to judge if the plan dimensions accurately reflect the true fit of the trim slot. Unfortunately, they don't quite fit - the gap is too wide to be covered effectively by the piano hinge.
I had previously cut a chunk of 025 to the flat dimensions called for in the plans. This the same dimension I used for my mock up piece. This wasn't going to work. The challenge is making the strip wide enough to account for the bends, the depth of the trim tab, the fore/aft distance in the slot and the overlap where they meet the hinge......hmmm....
After much thinking over breakfast coffee it dawned on me - why constrain myself to the flat part size listed in the plans. Why not cut the flat dimensions a bit wider or taller, then trim once I'm happy with the fit? I hate wasting aluminum in this way, but if I oversize the flat dimension enough to clearly cover the trim tab and enough to make use of the cutoff for something else, there won't be any worse waste.
At minimum, I'll salvage the cutoff and my original flat piece for other things yet to be fabricated.
First bend is the small tab at the hinge joint. The bender does good work on this, but can't bend far enough closed on this radius, so I had to bend it down further by hand. Fastening it the bench and leaning on it with a 2x4 worked. Next I bent the lower angle on the bender - this one is much more open so it worked as expected.
I placed the sheet in the approximate position in the trim tab slot. Width is a bit close will trim it down a bit to avoid any interference with the trailind edge. It''s clear from this picture the sheet I cut is well wide enough to cover the return bend back to the hinge.
Next I started fitting the hinge. The key here is to align the hinge left to right to take best advantage of a full barrel at each end. The barrel of the hinge alse needs to fit snug up against the trim spar. I used a small spare piece of hinge to mark out the correct length and it fits perfectly to the spar laterally.
On top is the spare hinge, length marked in green and my new hinge below it marked in red where I want to cut it
A chop saw makes quick work of the folded hinge, cutting though it evenly and easily. For the next step I pulled the pin out and ground down one side of the hinge arms to accommodate the safety wire required at each end to prevent the hinge pin from working it out - that would be bad!
To allow for safety wire, the hinge pin is slightly shortened to be just long enough to reach the last barrel at each end.
I remembered someone online suggesting using the bench grinder to slightly chamfer the rod ends to make sliding it back down the barrels easier. Just a small thing but made all the difference when reassembling the hinge several times over the course of this work. I also plan on using similar hinge to close up the engine cowling which will be open and closed more frequently - more on that later.
I flipped the elevator over again. When I was drilling the elevator skin, I didn't drill the holes where the skin meets the trim spar because I was waiting to see how the hinge would fit. As it turns out, this was a good idea, it saved me having to drill twice. I marked out the 40 pitch hole placement, placed the un-drilled hinge between the skin and trim spar and drilled it out to A3 (picture is after layout hinge pin not placed as of yet).
With the hinge apart again, careful drill of a small hole through the last barrel at each end to thread the safety wire when final assembly of the trim tab is complete. In this picture, I've already drilled out the 40 pitch A3 holes on the spar side of the hinge. Folding it over on itself, I marked the holes though to the trim tab side of the hinge (black marker dots on the left), then used this as a centre line (black) for plotting my holes on that side. I decided to offset them 20 mm from the spar side (blue tick marks)
Flip the elevator back over for viewing and dry fit of hinge to confirm safety wire hole is accessible AND viewable, both for installation and for routine pre-flight checks. From here I removed the hinge again and drilled out the A3 holes on the trim tab side of the hinge as marked.
With the bend width confirmed, I used the bender to create the trailing edge bend. It's tight and the bender can only bend so far over. From here, a 2x4 it used to lean on it and bend it further down to match the first. This picture clearly shows the long side of the trim tab will extend well beyond where it should - just like I planned.
With it close to coming together I flipped the entire thing over and secured it to the bench. This gives a much better view of the planned overhang. A quick sharpie line down the length gives a good line for trimming away the excess.
I drilled both ends of the trim side of the hinge to the trim tab and one in the middle for good measure. With it clecoed together in these three spots, I ressembled the hinge halves, clecoed it to the spar/skin side. Next, I proceeded to drill the rest of the trim side of the hinge to the trim tab using the previously drilled holes as a guide.
Took the whole thing off the elevator (again) and used the duplicator to match the holes on the overlap trim tab skin. I love this tool!
With everything clecoed together again, I checked the movement - nice and smooth and no binding.
With everything good, drilled everything out to A4 final size
Voila! (gratuitous happy moment capture)
With a few more minutes to spare, I decided to put everything on the bench again and line it up. Before doing that, I made the modification to the centre hinge plate that will allow the elevator nose skins the room needed to move up and down. I also trimmed the nose skin slightly to avoid any interference with the centre hinge support bracket.
With everything lining up and measured correctly, and confirming the whole assembly is flat and level, I marked out where the centre hinge bracket meets the elevator hinge spar bracket. With those marked where they meet, I took them off their respective assemblies for drilling.
I started with an A3 hole which will be enlarged to the correct size next. Holding it together with an A3 cleco, I confirmed they won't interfere when the elevator pivots up and down.
I stopped here, because when I was reviewing the plans, I have concerns about the size and type of the bolt used as the hinge pivot. The plans call for an AN3 bolt and vinyl insert lock nut. Not only does this seem awful small diameter, I believe it would be wiser to up-size the bolt diameter to an AN4 bolt and use a castle-nut and cotter pin to secure it. This mod is an improvement, I'll have to do some research what size bushing that will require.
Very happy with what I've accomplished so far. Next up is finishing the elevator/stab connections and fitting the servo and trim actuator rod.
Thanks for reading :)
I'm finding it more and more difficult to keep my blog up to date - I've accomplished much in the last few weeks. A lot of it has been routine fitting, drilling, cleco stuff so I haven't been taking many pictures. There are a few updates to share though.
With the one side partly secured with clecos, I moved the stab to the other bench. A large square steel tube was placed on the top to gently bend the skin partially into position before we tightened the ratchet straps to pull the skin down tight around the nose and upper surface.
Long strips of wood help spread the strap loads across the length allowing for fine adjustment. You have to be real careful here, too tight and the skin can collapse at the nose, leading to damaging kinks.
With the fit confirmed, I made a few reference marks, then it all comes apart and I can start the process of measuring the skin for holes. This is the only way to make sure the skin rivets are centered on the ribs as I don't have the luxury of pre-drilled skins.
Measure twice and then twice again, using the stab skeleton as a reference.
Again, I don't have any photos of the assembly, but the process is the same as above - weigh down the skin with the metal tube, use the straps to draw the skin down tight. The only thing that's different this time is drilling through the skin holes and into the structure below. I worked from the nose back to the rear edge (right to left in the photo) and from centre section out to the tips. Each hole gets a cleco until the rear most holes, ensuring a tight and bubble free fit.
Spar lines front and rear are drawn and rivet holes drilled. These don't have to be done with the skin off as the spar is a straight line and on this side the spar isn't pre-drilled. Again, measure 3 times - it's important the spar holes are centred on the spar flange:
I'm happy with how this turned out. Next step was using the template I made earlier to start laying out the slots for the horizontal stab brackets
This cutting is very delicate. The skin needs to be trimmed to be flush with the spar so the brackets sit flat and vertical against the spar. Cutting the skin is fairly easy, but any damage to the spar will be fatal!
I traced out the approximate location of the slots using the template and confirming with the plans started a pilot hole
I used a Dremel tool and rotary burl bit to slowly expand the hole enough so i could see where the rivet holes in the spar for the bracket are:
With a confirmed visual and measured slot location, I redrew the hole on the skin and slowly used the burr and some gentle hand filing to get it to the correct shape and location, ever mindful not to cut or mark the spar. Round files make a perfect corner:
Eventually with patience, the stab bracket fits nice and straight in the hole and perfectly vertical and flush with the spar underneath (it's sitting a little low inside the stab here as I couldn't hold it and take a photo at the same time!)
With that experience, the second slot went well too. I cleaned up the ragged edges a bit using a Dremel sanding/cutoff disc. The slots still have to be deburred properly, but that will come when the skin is off for full deburring:
On another note, Dad and I travelled to St. Hubert airport outisde of Montreal to attend the first flight of a C47/DC3 know as C-FDTD. We've been following the epic journey of Mikey McBryan (of Ice Pilots fame) and his Plane Savers team as they restore to flight a WW2 D-day survivor - a DC3 that dropped paratroopers over Normandy on D-day and during operation Market Garden, and that was sitting derelict, falling victim to vandals and the passage of time being slowly destroyed by neglect.
Here are a few personal pics of that trip - motivational for sure! For a full experience and to see what an amazing accomplishment this is, checkout www.planesavers.ca - of particular interest, watch the YouTube segments from the beginning - awesome and well worth your time!
Here is a copy of the flyer they were handing out to guests:
What an honour to be there and share this with Dad and the thousands of others who followed the restoration was unbelievably amazing..... what a great feeling watching it take to the sky again! All I could think about were are brave young countrymen that participated in the D-Day invasion exactly 75 years prior - God bless them and thank you for our freedoms!
I was so happy to share this adventure with Dad. As I post this blog on Father's Day, I'm reminded how much influence Dad has had on my life, particularly a love for aviation history. Thanks Dad!
While in the Montreal area, I also picked up a left/right set of fibreglass wingtips for my 750. These retail for $160USD a piece and I grabbed this uncut pair for $100CAD. Steal!
So, it's been a productive couple of weeks. Next up, I'll finish the stab skin, get the stab brackets installed permanently and proceed to skin the elevator. Once I have it skinned, I begin the process to line them up together and drill the mount holes for the hinge points.
Thanks for reading, more to come :)
Getting close enough to getting the 701 wing completed, it's time to start planning the rest of the tail group on my 750. That means ordering some aluminum!
I called the supplier (Aircraft Spruce Canada) and ordered all the 016 I need for the entire build, a sheet of 025 to replace what I've used from Ron and some elevator trim tab hinge. The plan was to go last weekend, but the huge storm that dumped on southern Ontario precluded the trip so instead we loaded up the truck and headed south this weekend.
We arrived in Brantford and convenient for the girls, an equestrian riding store is about a kilometer away from ACS. I dropped them off and headed to ACS to pick up my order and some items for Ron.
The staff at ACS are fantastic - I had asked them to roll the aluminum as small as possible in order to fit it under the tonneau cover of our truck and keep it out of the winter weather. They are masters!
In addition to stopping at ACS, I had been in contact with another 750STOL builder in Burlington - Ghazan Hieder. Ghazan has been slowly working on his kit for about 10 years and self admits that any upgrade that comes out from Zenair he buys, so when edition 3 cabin changes were announced, he bought the plans and updated parts, making some edition 2 parts available. He had advertised on the Zenair Builders website he was giving away an edition 2 cabin frame and windshield, so I made arrangements to meet up with him while down south to take possession of these two valuable items.
He was glad I called as he had hoped to find another builder who could use these items - and I was glad to take them off his hands. All the research I could find shows only minor modifications need to be made to the cabin frame and the windshield is another easy mod.
Ghazan also offered me an early edition nose wheel fork and nose strut - he'd replaced his with Viking steel spring mod, something I'm considering too. If I can't use the strut he gave me, it will work for one of Ron's 701 builds.
Brenda helped me load everything into the truck as best we could, but we decided to put the windshield in the back seat until we could work in the daylight the next morning.
With better lighting, it was easy to pack everything safe ans secure. I borrowed some moving blankets from a buddy and laid them out in a way to protect the plastic edges of the windshield and the sharp edges of the cabin frame.
Getting it home safely worked really well, thanks to Brenda's amazing packing skills!
Unpacking it all at the shop, here is a better look:
Needless to say, I am truly thankful to Ghazan for his generous donation. He could have just tossed these away (frankly I'm surprised no one else came forward to take them) but he didn't - he just wanted someone else to use them on an airplane. Estimates are hard to nail down because I have no idea what this stuff would cost to ship, but conservatively? I saved about $800+ by picking up these surplus (to another builder) parts!
One of the coolest things I've learned about the homebuilding community is how keenly interested everyone is in other people's builds and more importantly successes. I have or am learning the skills to make these work for my build and that works for me, whereas Ghazan is happy to build from a factory kit. Either way we share a common bond - dream, build, fly!
Thanks for reading!
Yup, I said it..... no, I can't speak german... thanks Google translate.....ha ha!
The Corvair authority William Wynne talks extensively on his blog about different carb applications in a Corvair conversion and the importance of keeping things simple.
The dual (and sometimes quad) factory Rochester carb setup on a Corvair car engine not only complicates matters (syncing throttles arms, etc) they were never designed for altitude compensation and mixture settings required in an aviation application. The converted Corvair engine falls into the same horsepower range roughly equivalent to typical medium Continentals and Lycomings, approximately 100 to 120HP. This requires a fuel delivery system capable of delivering an air to fuel ratio capable of supporting this demand.
Fuel injection? I believe the advantages (no carb icing, small increases in HP) are FAR outweighed by the complex system components (injectors, return fuel lines, pumps, electronics, sensors, etc). Keep it simple.
The MA3-SPA carb as found on the O-200 continental and O-235 Lycoming is the definition of simple. They haven't changed much since the 1940's and Marvel Schebler continues to make new ones today - in other words it works, simple. Overhauled to new specs it's the perfect carb for my conversion.
Finding one that is both inexpensive to obtain and overhaul becomes a problem due to this popularity. A good core for rebuild can be found in the three to four hundred dollar range then count on six to seven hundred dollars to overhaul it. Expensive, but not an area I want to save money on - engine reliability is important in flying! The recommended overhaul shop (D&G Supply in Michigan) also will convert specific O-300 carb models to the Corvair specifications.
Armed with this knowledge, I've been searching online for a suitable core.
A couple of weeks ago while surfing E-Bay, I came across a listing for an O-300 Marvel Schebler carburetor that would be suitable for my engine. It's clearly an older one, but again the model number matches the acceptable models for conversion and the pictures showed well.
Like anything on E-Bay, Kijiji or Craigslist it's a buyer beware mentality. One has to consider the odds and what it's going to cost to ship. In my case, the core I was interested in had no reserve pricing but the shipping costs weren't cheap - it was in Germany! This compounds the pricing with the Euro being somewhat strong against the Canadian dollar. Worth a shot.
With this in mind, I did the responsible thing and figured out my maximum bid would be about 100 Euros. I watched the days count down and was pleased to see my bid of 40 euros was enough to win! With shipping and currency conversion the total costs came to $112 Canadian. Not bad and certainly better than what I expected to pay for a core.
"Mein vergasser ist angekommen" (which means "my carb has arrived") on Friday and I picked it up at the post office yesterday. My first look had me really worried as the box had a crushed corner and was split open at the top:
There was a sticker on the box from Canada Post stating the box was damaged by the forwarding shipper. Not good. One of the fears shipping any item overseas or otherwise is theft. Hope there isn't just a bag of sand in here!
Opening the box, I smiled a bit finding a note from the seller:
Opening the box further, it came apparent that the shipper used a lot of bubble wrap to protect the carb on it's journey, but more importantly there is a carb inside the wrap!
It's definitely old, but everything seems intact and the throttle/mixture arms move freely. The accelerator pump seems seized but that's typical of something that has been sitting on a shelf for a long time and that will be repaired as part of the overhaul.
The data plate is intact and shows this is a model 10-4895 MS carb, typically used on O-300 engines. This is a good carb for overhaul and conversion to the required specs for my Corvair!
Glad I found this. It will be sent for overhaul this fall.
Back to the shop soon.
I made some excellent (small step) progress on my airplane build this past week.
Before I get into details, I want to share a bit of scrounging advice. Don't ever be afraid to ask around when you are looking for something, be it materials or tools.
While building, Ron and I often get to talking about ways to save on costs. One of the things that costs a bunch of money when getting it done by others is powder coating parts. Powder coating is a dry finishing process that gives various materials a durable coating that can be much tougher than paint alone. It's particularly good on non load bearing parts that may be handled regularly or exposed to friction. Control columns and rudder pedals come to mind.
Powder coatings are based on polymer resin systems, combined with curratives, pigments, and other additives and ground to a fine powder. A process called electrostatic spray deposition (ESD) is typically used to apply the resin to the metal substrate. The process uses a spray gun which applies an electrostatic charge to the powder particles which are attracted to the grounded part. After application of the powder coating, the parts enter a curing oven where, with the addition of heat, the coating chemically reacts to produce long molecular chains, resulting in high cross-link density.
That's the long way of saying "it sprays on and sticks really well after being cured in the oven".... ha!
Ron and I both figure the majority of the parts we might want powder coated should be able to be done ourselves. Ron has a source for the powder coating gun and resins, we just need an oven. Baking resins can generate a fair amount of unpleasant fumes, so we won't be using the kitchen!
I've been real fortunate over the course of the last few years to have several people I know come to me with leads on "airplane stuff" and I owe a bunch of that to talking to everyone I know about my project and plans. Opinions regarding my sanity range from "wow, that's cool" to "you are bat-s%$t crazy dude!" However, even if the vast majority consider me closer to the slightly crazy side of the scale, they do come to me when they hear of something.
In this case, when I mentioned that we were seeking an oven, Brenda noticed a Facebook post from a friend of a friend who was remodeling their kitchen. Turns out they were giving away a built in Jen-Air oven! Free! Brenda messaged them, I hopped in the truck and 10 minutes later, it was in our possession. We really don't need the stove top portion for baking parts so this is perfect:
We'll build a simple stand and wire it for power. It will require some calibration tests to ensure the temperature settings are accurate as they need to be for the powder coating. Not every oven is created equally as far as accuracy is concerned and oven temperature can drift as much as 25 to 50 degrees over time.
As for my airplane, I started to put the templates I made to use and traced out my first parts with them.
They worked real good. A thick Sharpie marker leaves a good line for rough cutting:
Before making the rough cuts of individual pieces from the sheet, now is the time to drill the corner relief holes where reuired. Here are some that I remembered to drill before cutting them out. Much easier to do this before hand I've learned!
Once the parts are rough cut out (thicker pieces on the bandsaw), further fine cuts are made using hand tools. By always leaving a bit of the thick marker line, we can see where the part will be trimmed down with the grinder, a file or hand sanding when taking of the burrs.
I made several parts over a couple of hours:
I took a good idea from Ron and taped the template to the parts when they were done. That way I don't have to write the part numbers on the aluminum. These completed parts will be stored until I need them later. I'm keeping a massive spreadsheet to track parts made, where they are stored and what inventory of materials I have on hand:
I know I have a TON of parts still to make, some simple, some complex.... but there is something so motivating about making these first parts for my 750 that makes me want to be in the shop full time. Unfortunately without spending at least some of my waking hours at my paying job, I can't afford the materials to make parts, so I guess I'll have to get back to the shop when I can.
Next up, further repairs to the 701 wing and I'll finish the sub assembly parts I need for the tail group on my 750!
Snuck over to the shop for a couple of hours Monday morning. I'm trying to squeeze in time when I can and a few hours in the morning before I head to bed for my afternoon pre-nightshift nap works perfectly.
Work continues on the 701 wing repair/rebuild. I managed to fabricate my first replacement piece, a rear wing channel. It took some time to figure out how to use the sheet metal bending brake, but I got it done. Here you can see the original bent and mangled one on the right and my new one on the left. The previous builder for some reason made his channel with a thinner gauge of material than what the plans call for. I'm all for saving weight and money, but this is a critical structural component, not something I would consider worth skimping on:
Next was removal of the damaged nose skin. As part of the repair/rebuild, Ron is planning on extending the wing by a couple of feet. We'll cut out the damage, fabricate a tip extension to the main wing spar and add a rib where required. A new nose skin and upper/lower wing skins and will be cut and fastened to the originals. Of course, this means drilling out more rivets. I suspect there will be times this will come in handy when I make mistakes on my own build!
This picture shows the extent of damage. What do you think..... is this creased too far to be "popped out"?
I drilled out the rivets on the closest good rib to allow some flexibility when cutting the bad nose skin. We'll trim it cleanly back to the rib to enable a clean joint with the new extended skin. These empty holes will become part of the stronger joint as a result.
As always, I'm keeping my eyes open for good deals on things I need for my project. Surfing the classifieds section of the Ultralight Pilots Assocication website, I came across an individual selling a complete rudder section for a CH750 for an amazing price that was too good to be true! A quick game of phone tag and the seller and I agreed to meet on Friday this week.
On the road again..... can't wait to get on the road again.....
Previously on part one.....
Without the resistance of the blower fan and suction of the vacuum filter assembly, this motor spins way faster than what the label states. So fast in fact it wants to tear itself apart while merrily dancing across the shop floor despite being mounted on springs (or maybe because it's mounted on springs?)
So, I need to figure out a way to slow the motor down or reduce the vibration component.
My first thought is to reduce the size of or modify the shape of the metal strip I added to the motor axle.
I think doing this only reduces the vibration. The motor will still be spinning way too fast and determining the right size of strip may be hit and miss to get exactly right.
How about controlling the motor speed? I think this will be the easier route.
Digging through my box of household electrical stuff, I found two incandescent dimmer switches that should work. They are designed for AC power (as is the electric motor) and this would add the ability to fine tune the vibratory effect for best results.
Before that however, I need to finish creating the parts bowl. First I inverted the bowl and traced a circle on a piece of spare lucite (plexiglass):
Cut the circle out using my bandsaw...... that's when I realized the centre section of the bowl sits above the rim:
To secure the new lid, I used a piece of hollow threaded rod. I screwed it into the top plate of the tumbler and l left it long enough to add a cap to hold it down tight to the bowl:
To hold the lid, I found an old powder scoop that fits perfectly over the bowl centre. That and a washer and nut hold everything down nicely:
Now that everything is built, back to slowing down the motor.
I added in the rotary dimmer switch. It has an off position when turned counter-clockwise all the way. I'll tide up the wiring once I figure out if this is going to work as designed. The picture was taken prior to creating the lid. Using the dimmer works!
Time to test the machine....
First, add the tumbling media, in this case a couple of scoops of clean clay cat litter. Then add some dirty, greasy and rusty test parts:
Close and fasten the lid..... all secure and "go for power-up!" The vibrating of the tumbler makes it hard to get a clear picture, but the media very quickly envelops the parts. As it tumbles, they occasionally come back up the top:
The tumbler is NOISY! I suspect the bolts between the levels of the tumbler are vibrating against the bowl. That should be easy to fix. Perhaps it might have to be run outside. After letting it run for about five minutes, I decided to have a look at the progress. Even after only 5 minutes, the parts are obviously cleaner and devoid of the grime they entered with:
Although the parts come out a bit dusty, clearly this method and machine I've built works very well, even at a short duration. I'm planning on running a longer test this afternoon and will post more details.
So as I mentioned previously, I have a pail full of loose hardware (bolts, nuts, washers etc.) that are completely covered in dirt, grime and rust. I pondered using my daughter's rotary rock tumbler, but learned that the interior of the drum can get destroyed by the tumbling medium and the metal parts.
A quick Google search led me to this post on how to make a Vibratory Tumbler:
The tumbler described in the link above is for rocks, but the concept is simple enough, perhaps I can come up with something for cleaning my parts. Another Google search led me to this You-Tube video:
Now that seems more like the type of task I'm trying to accomplish! And the cleaning media is cat litter!
Shouldn't get much cheaper and easier than that! Let's build one!
First, I obtained the following two items from the Value Village thrift store:
I tested the vacuum in the store before purchasing it to make sure it worked. It was missing the nozzle extension, so as a vacuum it really was worthless..... but it's the 9000 rpm electric motor that's inside I'm after. Recycling at it's best!
Remove the filter section and split the main case open:
Remove the motor/blower assembly and filter gasket:
Pry off the outer housing with a small screwdriver and remove the blower fan:
I removed the plastic backing plate leaving just the motor assembly. The mounting screws are quite short so I needed a thin board to mount the motor to. I had an old poly cutting board (white one on the bottom of the picture below) that I wasn't using for anything. I drilled out a large hole in it for the motor axle and two smaller holes for the mounting screws. The upper board is where the bowl will sit, for this I used a piece of scrap laminate flooring I had kicking around. I used 6 inch bolts with lock washers and nuts to space them apart enough to fit the motor in between. This whole assembly will be the vibratory part:
Next, I mounted the vibratory assembly on compression springs I bought in the surplus aisle at Princess Auto. Then the whole thing is mounted on a base of wood:
Next I mounted the motor. In the vacuum, it was designed to spin at high speed and very smoothly.
In my application, I want the motor to continue to spin at a high speed, but to also vibrate at high frequency. To accomplish this, I attached a small strip of scrap metal to the fan mounting bolt/axle of the electric motor:
So... thinking all was good, I figured it was time to test it. I very quickly learned that the motor was designed to power the blower fan with the added resistance of trying to move the air through the vacuum filter. Although I did plug in the motor and tested it once I had it outside of the vacuum housing and disconnected from the blower I didn't think much of it. However, without this resistance, I believe the motor spins much MUCH faster than it's rated RPM. Adding the attached metal strip and the whole assembly almost jumped and bounced across the shop floor base and all when I applied power. I should have tested this before mounting it, but it probably would have ripped my hand off in the process.
This obviously won't do.
More to think about..... stay tuned for part two.
So here is a first look at some of the highlights of my find.
There are a LOT of parts to go through and inventory, but I can't begin to explain how stoked I am about my acquisitions.
Most of everything is either salvageable as is, prime for exchange as a core for re-manufacture, or trade-worthy for other things I will need.
Casting numbers (T1208RH) on the dis-assembled core block indicate a 1965/66/67 110HP "automatic transmission no smog" block manufactured on December 8th in either 1965, 66 or 67.
The casting numbers (3878566) on the heads from this core indicate 110HP from 65, 66 or 67.
These are prime candidates for conversion. Two things I haven't found in the boxes yet are the camshaft (but that isn't a game-stopper as it will be replaced by a custom cam anyhow) and the push-rod tubes (cheap to purchase new). Everything else important seems to be there.
The original cylinders, pistons and rods from this 110hp core are in great shape and will be excellent core exchanges.
The crankshaft is the correct model (8409 cast iron) for conversion. It has already (as far as I can tell and was told) been drilled for the prop hub and safety shaft. I'm not sure if it has been nitrided or not, should be easy to find out. Huge savings having this already complete.
The new in box pistons I got with this lot have been superseded in the latest conversion plans with dished and forged aluminum pistons. Perhaps these can be traded or sold.
I paid a bit extra to obtain the prop hub assembly. It includes the machined safety shaft called for in the conversion plans. A new one from William Wynne costs over $500USD, I got it for $50CAD. Great deal!
The second core is still almost completely assembled and appears on the outside to be super clean. The valve covers even have some of their factory chrome finish left on them. The cooling fins are real nice and straight on both the cylinders and the heads.
Casting numbers (T1214RM) on the dis-assembled core block indicate a 1965 or 66 140HP "manual transmission no smog" block manufactured on December 14th in either 1965 or 66. It would be neat to know if both this and the other 110HP block were made within 6 days of each other!
The casting numbers (3878570) on the heads from this core indicate 140HP from 65 or 66.
This block is also a prime candidate for conversion. The heads however would have to be directly replaced with 95HP or 110HP heads. They will be of value to someone, probably a car rebuilder (140HP heads are rare). Of course the crank and camshaft are still inside and the push-rod tubes are there as well. I haven't looked inside this motor yet Everything else important seems to be there on this core too.
Although not pictured, Paul also included new in the box set of chrome piston rings and a David Clark headset (which appears new from the box!).
So, I think it's fair to say I've got a running head start on my engine project. A complete inventory is next. Time to buy some storage totes :)
On another note, I'd be remiss in not mentioning the support for this mission that has been given to me by my wife Brenda. She always seems to guide me away from to good to be true deals to hidden ones like these. Thanks - I love you.
Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.