The last week of summer has come and gone. We made a family mini vacation to southern Ontario and took in the Brantford Community Charity Airshow among other things. It was an awesome airshow with quite the collection of warbirds, aerobatics and of course the Canadian Forces Snowbirds!
Also located at the same airport is Aircraft Spruce, one of the biggest suppliers of aircraft parts, pilot gear and building supplies. I had placed an order the week before and was able to pick up 3 rolls of aluminum sheet to be used in my build. Ron and Donna were also at the airshow and were kind enough to bring the rolls back north with them to the shop, saving us having to drag them around on the rest of our family trip.
I also stopped at KBC Tools in Missisauga and picked up a couple of really handy items. First, I've been reading about how to cut long straight edges on aluminum sheet. Some of the spars and doublers I have to make for my airplane are too long to be easily cut by shears. Even local machine shops in my area are either unable to handle the widths or too expensive.
One of the solutions on the Zenair builder's forums caught my eye. It involves making a aluminum cutting knife out of a carbide machine shop grooving insert attached to a handle, in this case a old crescent wrench.
I found the grooving insert at KBC tools. It's expensive for it's size, but is able to make very thin cuts in aluminum. For a couple of dollars more, I opted for the Titanium nitride coated insert making it more durable:
For a donor handle, I used an old crescent wrench with a seized head. I cut the head off at a 110 degree angle at the narrowest part of the handle using the chop saw:
Cleaned it up on the grinder.....
Next I used a combination of Dremmel tools and hand files to carve a shallow groove in the handle for the insert to rest in:
I made a test cut on a scrap piece of aluminum and this tool cuts it nice, clean and straight and only requires a couple of passes to score the aluminum enough for breaking. MUCH faster than using a laminate blade like an Olfa.
The other tool I picked up at KBC Tools was a NOGA Rotodrive countersink/deburring tool:
This is a much quicker and simple way to deburr dril holes. It is a rotating "dog-leg" countersink and with a very light touch and two turns will remove drilling burs without countersinking the hole. Lightweight and fast, it will be super handy as I progress through building. Much better than rolling an oversize drill bit between the fingers.
I continued work on the wing tip extension. I fabricated two (one for each wing) spar web doublers out of 0.032 sheet on the bandsaw. These will be the bread of the sandwich where the tip extension and spar web meet:
Laid out the proper rivet spacing and matched drilled them together:
Mounted the assembly to the wing spar web and match drilled the par caps, then clecoed everything together to confirm alignment:
With the assembly temporarily in place, the next problem needs to be solved. How to match drill to the original holes in the spar web (inclunding the orginal outer wing rib) without any access inside this part of the wing? As you know, the previous builder just eyeballed things so measuring what is already there won't be accurate enough. I could pull more of the wing skins off and back drill through the new doubler, but there is an easier way!
Introducing the "rivet hole duplicator". This ingenious tool allows you to match drill to holes behind the sheet aluminum. It consists of two straps of spring steel, one with a hole locator and the other with a drill guide:
With this tool, it's simple to find the right spot to drill each pilot hole. The pin tang slides in behind the panel you are drilling and the guide lines right up to where your new pilot hole should be..... GENIOUS!
Duplicate holes on web spar (right side of joint centreline) are complete awaiting final rivets. We'll need to figure out what we are doing on the back side to extend the spar caps and sandwich everything together but for now, this should be easily repeatable on the second wing:
With that complete, I took some time to fabricate the wing slat ribs from some spare 0.016 sheet.
There are 12 of them required, 6 in each wing slat. So I traced them out from the template, trying to use up as little real estate as possible. This will become more important later on when cutting other multiple items from full sheets:
One of the lessons learned earlier when I was making tail ribs was to centre punch and drill the relief and tooling holes before cutting out the metal, so I did that here first:
I discovered that the elevator tip rib form I traced out was undersized by about 2%. So I corrected the form and made the tip ribs with the correct aluminum template. Glad I caught this now, not later when I begin assembly. Here they are awaiting bending:
Very please at the progress I'm making. Coming up this week, I'm going to the woodshop to final trim and sand my plywood form blocks and I'll start tracing out the longer spar and doubler pieces for the horizontal stabilizer and elevators. Then I can start the assembly process!
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!
So back to the shop on yesterday, looking forward to flanging the root rib lightening holes.
When I set the flanging die up on the bench, I noticed that although my lightening holes are cut to a perfect 65mm diameter as per the plans, the outside diameter of the flanging tool above the shoulder (the one on the left) is also exactly 65mm, making it too tight a fit in the hole, and impossible to work correctly:
This means the holes I cut in the rib will need to be expanded just slightly.
There are a couple of ways I could accomplish this. To sand/grind the aluminum away to make the hole bigger would be quicker, but next to impossible to maintain a perfectly round circle.
Going back now with the flycutter set slightly wider presents an issue because there isn't any metal in the middle of the hole to centre the flycutter on and there is an increased risk of tearing.
I really didn't like the idea of ruining the perfectly symetric holes by grinding and hand sanding would take forever. Flycutter it is then!
To make another cut, I needed to add a piece of scrap aluminum to the back of the rib. Luckily, I have just the piece left over from the damaged rear channel (always save stuff you might use later). Here the sacrificial piece is riveted in place on the back side of the rib:
With slow and careful application of the flycutter, the new diameters are cut, maintaining the centricity of the circles. Now I know to make the lightening holes slightly larger to fir the dies. I'm pleased it worked okay, I was real concerned removing such a small amount may lead to a tear in the rib:
A quick drill out of the attachment rivets and voila, one rib ready for deburring (again) and flanging:
Deburring the lightening holes is very time consuming. I think I'm going to investigate what 3M Scotchbrite wheels will work on them.
The process to flange the holes using a die is much quicker than working them by hand tools. First, set the rib on the male side of the die:
Place the female side of the die on top, making sure the flange will press out in the correct directions according to the plan (in this case the same as the outside edge flanges):
Although it would be much faster in a hydraulic press, enough force can be exerted using a C-clamp and the bench top edge to accomplish this. For this size die, one clamp is enough, but on larger dies, multiple clamps would be used:
Squeezing of the clamp leaves a wonderfully even and clean flange:
Now that understand the process, making the ribs for my 750 will be much quicker.
I finished the day by doing further final work on the missing wing root doubler. Lots of back drilling of pilot holes, final match drilling and thinking about what can be riveted ahead of other items etc. I'm to the point of having everything ready for final fitting. I flipped the wing over to get better access to the doubler. The wing attach fitting in the lower left is the bent original with the terrible out of round bolt hole. I've clecoed back in place as a guide for backdrilling out the web doubler and new wing attach bracket:
So far so good. I'm really getting a handle on what it means to pilot drill, cleco, match drill, cleco, take apart, deburr, cleco again and final drill.... just to take apart again for deburring, cleco and final rivet. All important steps that mean a well built airplane.... something that the previous builder didn't seem to understand.
Got to the shop this morning for a couple of hours. Trying to squeeze in a bit of time here and there before going to sleep before nightshifts.
First thing I finished off was the fuel tank bay inboard wing rib cap repair. Finished deburring the holes, both the old bad ones and my new ones to prevent any further cracking. The new cap repair is really stout and should give a great surface to attach the wing skin back on compared to the original rib flange which was mangled by the previous builder:
The missing wing root doubler has been drilled according to the plans and is clecoed in place. I've yet to decide which order to rivet this in place, but I'm going to wait until we have all the other items (nose rib, root nose rib, root rib, wing attach bracket, etc) gathered so I can test assemble and measure everything. This took a lot of careful back drilling through the spar web to get it right, and I'm happy with it so far:
In a lot of places of any given airframe, the designers of light aircraft take advantage of the inherent structural strength of aluminum to lighten the overall structure of the aircraft (lighter is better). A common method is the use of lightening holes. You can see them (the large circles) in the spar web of the above picture.
Lightening holes serve a number of purposes besides weight reduction (obvious). Wiring, hydraulics and or fuel lines can be passed through these easily. It also provides an opening for inspection of control linkages that might be inside otherwise closed cavities without having to remove the skins. The most common place they are used is in wing ribs, including the replacement root wing rib I'm currently making for the 701.
Lightening holes are also flanged which provides even more rigidity to the part (more on this in a future post).
Making lightening holes is where the fly cutter tool really shines. Cutting perfectly round holes by hand is near impossible.
So what is a fly cutter?
I particularly like the quote from the machinist that it's like "running a lawn mower without the deck". After drilling my into my hand a week ago (I'm fine by the way), I'll take this as a warning!
The fly cutter I used is a single arm one. It's like a high speed compass that cuts metal:
Adjusted to the right radius/diameter required using the set screws and placed into the drill chuck. When spinning it clearly will hurt you if it's not respected! Here it is with the root rib:
The only safe way to use the fly cutter is to clamp the part being cut down to the drill press table and keep you hands well clear. Trying to stop a piece of spinning aluminum should the cutter jam would be foolhardy. I used wooden blocks to prevent marring the aluminum with the C-clamps. It was also important to make sure the clamps were clear of the rotating fly cutter arm (that also would be very bad):
The secret with any machine tool cutting is to go slow and steady and use lots of lubrication. Once lined up correctly, I began to make the cut, adding a little WD40 as I went. Here is the cut well into the process (yes, the drill was stopped for the picture):
As soon as the cutter breaks through, pressure is lifted to prevent a chance that the cutter tearing the remaining aluminum.
Re-position and cut two more holes without issue. It takes a bit of time and I'll have a ton to do for my 750 parts, but it's worth it to have nice clean holes. Here is the root rib with all three holes cut and the cut out discs. They are sharp, I wonder if that's how they make pizza cutting wheels for the kitchen!:
All cleaned up and waiting for deburring and flanges. Looks great!
Next up, flanges! Stay tuned and thanks for reading :)
Looking back I can't believe it's been almost a month and half since I posted to the blog. I've been busy waiting on some stuff I ordered to take the next steps on the motor rebuild and some travel to visit family in Ann Arbor Michigan took up a bunch of time as well. Well worth it though, we needed a quick family get-away to recharge.
Since my last post, I took my engine block into the machine shop to fix the snapped stud issue. They have a highly accurate CNC milling machine which will make short work of the snapped stud. The process will remove the remnants of the broken stud but this will also mean sacraficing the hole threads. I've now got the TimeSert install kit that I ordered which will repair the damage and create a new set of threads to insert the studs into.
Until I get the block back from the machinist early next week, I got some of the prep work needed for the studs done. The original short (lower) head studs from my core engines are in decent shape, but typically very dirty with some light surface rust. The push rod tubes are similar. Here is the before pic:
The perfect tool to clean these is the bench grinder. This one is a beautiful old school one. I prefer old tools that are made to last:
The wire wheel makes short work of cleaning of the decades of old grime and rust and is excellent for cleaning up the stud threads:
The push rod tubes from the core are really dirty. Under the grime, the tube was manufactured with two coatings on top of the bare metal, as shown in this picture from Google:
I had a go with the wire wheel on one of my tubes and this was the result:
I'm happy with how they cleaned up, particularly around the o-ring area. However, after seeing the picture from Google that I found for tonight's blog entry, I'm not sure if I've just removed the grime, or removed the zinc coating as well. Removing the zinc coating and getting down to the bare steel is what I want to do as this will allow me to paint (or maybe powdercoat) them white as described in the conversion manual. I'll have another look next time I'm in the shop. These may require a bit more work. The one in the picture I copied was sandlasted, perhaps that's what I'll end up doing.
Overall, the first twelve studs all came out really nice and clean - they should paint up real nice. There are some minor tool marks on each. I have a bunch more in the inventory, so I'll clean those up too and choose the best ones for the build:
The other task I've been pondering is cutting new threads on the end of those studs being inserted into the TimeSert holes of the block.
The studs on Corvair engines are made from a very high tensile steel alloy. The original threads at the block end are a proprietary GM thread called 38-16 NC5. These will not fit the TimeSert which are the more common 3/8-16 NC. So, for those holes that I'm installing TimeSerts, I'll have to use a die cutter and rework the threads to be 3/8-16 NC. The head end doesn't need to be altered.
I had a bit of time today, so I took one of the old long (upper) studs that are being replaced with new ones due to corrosion and experimented cutting new threads on it. Best case, I see how easy or difficult it is, worst case I ruin an old stud that I won't be using anyhow.
I clamped the stud tightly in the vise. When I do the good ones, I'll have to remember to put something in the jaws of the vise to prevent clamping damage marks. Here is a picture of the tools I used. I couldn't find where ron keeps his cutting oil (if there even is any), so I substituted a little 3-in-1.
There ins't a huge difference in the GM thread and the 3/8-16 I need to use with the TimeSerts. Carefully starting the die on the threads and using a fair amount of oil, I managed to cut or reshape the threads about under half way down. This involved the time proven method of turning the die down a little bit at a time, and backing off numerous times but it went marvelously well. Here's a close up:
When I got home, I test fitted this stud in a TimeSert and it threaded in real nice. I bit of LocTite 620 should make the repair as good or better than the factory fit. I've been worried about this process for a long time, but I think with a little attention and time, it's going to work out fine.
Next up, prepping the block for stud install.
A couple of more hours in the shop today. Work continues on the 701 wing rebuild.
Stripped off the last of the paint where the wing and nose skins will be replaced. A wipe down with acetone and it comes out real shiny! Next step will be to scuff the aluminium and paint it with primer in preparation for mating the new skins.
While I was letting the stripper soak in for the above step, I finally got up the nerve to clean and trim the nose skin where the damaged piece was cut away. Working from the outside, I wanted to make sure to cut not only straight but well away from the underlying nose rib. To make the task easier, I laid on a piece of painters tape outlining where I was going to cut:
The curve of the nose skin makes this difficult to use hand shears or metal snips. Bring on the power tools! Ron suggested using the air powered saw:
When it's running, the blade on the air saw moves faster than the eye can see. It's fine tooth blade made short and clean work of the skin. The last inch or so I did with metal snips to prevent accidentally cutting into the wing spar (that would be a unmitigated disaster!):
A productive couple of hours.
I've sent off a quote request to Zenair for a complete tail kit of my own, minus the rudder pieces I already have.
Friday finally got here and I departed home for my road trip to "parts south" at 1130am.
First stop, my long time friend Lynn's place just outisde Barrie. Lynn and I grew up in the same hometown of Holland Landing and her late father Wally owned the local airport. For several years Lynn was heavily involved with ultralight aircraft, as a builder, pilot and instructor. Now heading in a different direction in life, she contacted me with a list of items from sale from her collection.
As I arrived in her driveway, I was very pleasantly surprised to see that one of my best friends Mike (also from Holland Landing) was also there. It was just like old times - what a fantastic chance to catch up a bit. None of us has aged by the way ;)
Lynn had collected up a bunch of stuff for me and made a sales pitch I couldn't refuse. More on this in a bit.
Next stop, my parent's place to pick up Dad and head to Kitchener to see Scott about the 750 rudder he has for sale. I like taking Dad on these jaunts when possible. It's great to catch up and of course talk airplanes - it's certainly something in the DNA I got from him!
After a dinner in Guelph with Dad, we made our way to Scott's place in Kitchener. The deal for the rudder we agreed to got even sweeter when Scott included a box of Cleco fasteners, Cleco pliers and two heavy paper bags of A4 and A5 rivets - all for $100 cash! I didn't dicker or give him a chance to change his mind. START THE CAR!!
We wound our way back to Dad and Moms during Friday evening rush hour and seemed to hit every red light. Times like this remind me how much I enjoy living in northern Ontario. I decided to grab a nap for a couple of hours, but by 415am this morning, I was back on the road home (there are other things I have to get done before going back to work tomorrow!)
Once I got home and had some breakfast, I began the inventory process.... in a word, wow!
Here is a group photo of the items I obtained from Lynn and Scott. Top to bottom, left to right: A handful of the several reference books, bags of Cleco fasteners, over a thousand rivets (paper bags), Cleco pliers, drill bits "The Claw" aircraft tiedown kit and a "One Touch Tach" tool used for confirming prop RPM.
Amazing stuff for my project. In fairness to Lynn, I won't disclose what I paid for her portion of this stuff, but suffice to say, it pays to stay in touch with friends!
The big item of the trip however is the 750 rudder. Scott had attended a Zenair factory sponsored rudder workshop with the intent of getting a head-start on his 750 build, but as is often the case, life got in the way and he decided to part with his barely touched project. This rudder is already mostly built, including corrosion protection. Fortunately one side only has some temporary rivets on the skin that can be drilled out so I can confirm everything is good inside and run the wires for a navigation light. For $100 and the fact it was built in a supervised factory workshop I can drill a few rivets out to confirm. Unassembled rudder kits are more than $500 from the factory and there is at least $100 in hardware that he threw in.
Can't wait to show Ron!
But right now, the lawn needs to be cut.... again.
Before anyone thinks I am complaining that it took FOREVER for spring to arrive, rest assured, I am grateful. I'm also reminded by the "shared memories" of Facebook that it hasn't been that uncommon to have snow after or on Easter weekend in the past decade. At least spring appears to be here for good and we can cancel the arrest warrant for the Groundhog. He was wanted for fraud.
I got my FlyCorvair.com engine dis-assembly DVD this past week and watched it as a starting point for assessing the 140hp core.
It was a gorgeous afternoon today and I took the opportunity to pull out the engine stand I purchased with the two core motors:
With Brenda's help, we lifted the 140hp core up onto the mount. This gave me the chance to have a better all-around look at it. I placed it in a spot where the sun this morning would warm any oil inside with a plan to drain it this afternoon:
First step after letting the warm, beaming sunshine do it's thing, grab a wrench and bucket to remove the oil drain plug and catch any old oil that might be sitting in the oil pan:
I removed the oil drain plug and.... it's dry? I would have thought there would be some oil there, but even the threads on the bolt are dry.
I grabbed a 3/4 inch socket and ratchet and tried turning the crank at the harmonic balancer. It didn't seem as it is tightening at all. Watching the cam gear and crankshaft at the other end, they remained dead still..... hmmm. Maybe the engine is seized? No oil so it wouldn't surprise me. Weird that the harmonic balancer bolt just keeps turning. Must mean that whatever the bolt is threaded into is turning inside the oil cover.
This engine core already has the distributor removed. I looked down the distributor hole as I was turning the harmonic balancer bolt and I can see daylight?:
So... the daylight means something is missing on the other side.... namely the oil pump gears and associated cover:
That explains two things. The lack of oil in the pan (the oil pump gears are close to being the lowest part of the engine) and the crank not turning as I suspect the crank is seized (possibly bad news for taking apart the pistons and cylinders).
With the concerns I have with the 110hp core studs being damaged and snapped off, the other place I wanted to have a better look at was the studs on this motor, hoping to use this block instead. Sadly, it looks like someone previous tried to remove the studs, but at least they are complete and not broken. Hopefully they pass the torque test. If they pass, great. If not I'll replace them and use this block. Some look like they have been partially backed out from the block (not preferable) and one is completely out of the block. Thankfully all of them seem to have good threads and are clean:
Next thing I wanted to have a look at is the rocker arms under the covers. Oddly, the hold down clips are missing on the rocker covers and 1 of the 4 bolts is a different size.
My next hint that things aren't as they seemed was that the rocker cover I removed came off very easily. I started to get the picture that they had been removed already and put back by the previous owner:
Once the cover was off I got my first good look at the valve train. It became immediately obvious that there are some key pieces missing (the ones I found earlier in my inventory - now I know where they came from!). The rocker arms are loose enough to spin around their studs:
The pushrods are missing....
....and so are the valves, as evidenced by the empty valve guides, missing valve springs and keepers:
This is the final clue that tells me the heads have been previously removed. There is no way to remove a valve from the head without removing the head from the block. The valve's shape only allows it to come out from the combustion side of the head, therefore, this head (and likely the other one) have been removed previously. I have a bunch of valves, springs and retainers in my inventory. Guess I know where they came from! It also explains at least in part the lack of oil and the surface rust on the rocker arms (which will be replaced).
That these heads have been off previously this is good news. This should mean dis-assembly will be easier when I'm ready. In preparation, I've soaked the upper side head nuts on both sides in PB Blaster penetrating oil. I continue to soak them for several days before turning a wrench on them. If I'm careful I should be able to get the heads and cylinders off and have a good block to work with in my conversion.
That should be easier than fixing the 3 broken studs in my other core block. At least I have some options.
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.
Time until takeoff
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.