Crescendo Build
- Thread starter Brian Jackson
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Brian Jackson
Platinum Member
Thank you Jake. Was going more for a Hookah than a bonggyrojake;n1139323 said:
Actually the shapes of the fittings (and many other parts) was dictated by load; thickness can diminish at a proportion to length. I just removed material where it wasn't needed and you end up with the shape of pulled taffy.
Brian Jackson
Platinum Member
Ordered the wheels, tires, axles and innertubes today from Azusa. 6" and 4" AzusaLite wheels for the mains and nosewheel respectively. Not having ordered these types of parts before exposed my ignorance of many things. For example, tires... many tread types, plys, profiles, etc. But after studying their site and catalog for a couple of days I think my best guesses were at least somewhat educated before ordering. I went with simple Ribbed tires instead of other tread types like Knobby, Turf, Sawtooth, etc. Flat profile on the mains and round profile on the nose.
I did not order any bearings with the wheel halves because I am told these need to be replaced with better quality. Will be ordering them from Aircraft Spruce if an Aurora equivalent (or better) is available.
Axles... where to start. I relied on the Forum for guidance here because the GyroBee plans are vague here and simply spec "KB2 Axles". I did order 5/8" diameter solid steel X 8-3/4" long, no step, with a 1" threaded end. From the plans this appears to be the correct length. They are referred to as "Mini Axles" in the Azusa catalog. They will require aluminum sleeves that are 3/16" wall to fit tight. Since they are 5/8" diameter continuously, the thru-holes for the strut fittings will need to be centered very accurately to leave 3/16" of steel on either side of the hole. I'm a little concerned about this detail.
Anyway, that's where the project is at currently.
I did not order any bearings with the wheel halves because I am told these need to be replaced with better quality. Will be ordering them from Aircraft Spruce if an Aurora equivalent (or better) is available.
Axles... where to start. I relied on the Forum for guidance here because the GyroBee plans are vague here and simply spec "KB2 Axles". I did order 5/8" diameter solid steel X 8-3/4" long, no step, with a 1" threaded end. From the plans this appears to be the correct length. They are referred to as "Mini Axles" in the Azusa catalog. They will require aluminum sleeves that are 3/16" wall to fit tight. Since they are 5/8" diameter continuously, the thru-holes for the strut fittings will need to be centered very accurately to leave 3/16" of steel on either side of the hole. I'm a little concerned about this detail.
Anyway, that's where the project is at currently.
Last edited:
Brian Jackson
Platinum Member
Thanks Jake. I will analyze the photo when time permits this evening.
Also to add, I believe I may have misspoke about avoiding the Azusa wheel bearings in my earlier post. Searching the forum archives revealed a post I was incorrectly remembering that instructed to "Use the better bearings." It didn't say avoid them. So I apologize for the wrong information.
Also to add, I believe I may have misspoke about avoiding the Azusa wheel bearings in my earlier post. Searching the forum archives revealed a post I was incorrectly remembering that instructed to "Use the better bearings." It didn't say avoid them. So I apologize for the wrong information.
Jazzenjohn
Gold Supporter
Azusa has 2 levels of quality for their bearings. Super cheap stamped race loose bearings, and sealed bearings with hardened and ground races. I've never had a problem with the good ones.
Brian Jackson
Platinum Member
Good to know, John, and thank you. I ordered the Azusa precision bearings today from Aircraft Spruce. Was surprised they're less than $2 each. Bargains usually makes me skeptical.Jazzenjohn;n1139527 said:
Brian Jackson
Platinum Member
While the Forum is currently suffering some coding issues I'll add this entry that doesn't require photos. Bearings are seated, nosewheel assembled and inflated, and I went ahead and ordered the round profile tires for the mains to replace the square profiles I'd ordered earlier to reduce parasite drag. This was a good bit of practical knowledge available through this Forum that would be tragic to lose, so am hoping the Forum issues can be resolved soon.
Having conversed with Azusa Engineering directly, I have decided to bend the axles themselves rather than the axle strut tubes. This is allowed without the need for subsequent heat treatment, and the steel is ductile cold rolled so no issues with fracturing in the ~10 degree range needed.
Currently there are 2 fabrications going on: Strut connections for the tailboom supports, and lathe work for the axle inserts. Also fashioned a crude hoist from a ratcheting strap to make the ship a little easier to work on. Am confident the Forum will be running smoothly again by the time there's any interesting photos to post.
Having conversed with Azusa Engineering directly, I have decided to bend the axles themselves rather than the axle strut tubes. This is allowed without the need for subsequent heat treatment, and the steel is ductile cold rolled so no issues with fracturing in the ~10 degree range needed.
Currently there are 2 fabrications going on: Strut connections for the tailboom supports, and lathe work for the axle inserts. Also fashioned a crude hoist from a ratcheting strap to make the ship a little easier to work on. Am confident the Forum will be running smoothly again by the time there's any interesting photos to post.
Brian Jackson
Platinum Member
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Descriptions in photo panels. 2 more posts to follow with photos in each of the component parts for the tailboom support. The thinner airfoil shaped struts are in pre-load tension while the singular wider airfoil strut is in opposing compression. It is surprisingly lightweight (hollow machined cones) while being extremely rigid. The turnbuckle system provides a means to control pre-load stresses.
Descriptions in photo panels. 2 more posts to follow with photos in each of the component parts for the tailboom support. The thinner airfoil shaped struts are in pre-load tension while the singular wider airfoil strut is in opposing compression. It is surprisingly lightweight (hollow machined cones) while being extremely rigid. The turnbuckle system provides a means to control pre-load stresses.
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Brian Jackson
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Tailboom compression fitting. Not shown in photos are 2 opposing milled flats on the upper tenon sized to match the I.D. of the airfoil shaped compression strut extrusion. This is where the strut attachment bolt penetrates. The final part only weighs a couple of ounces yet it began as a 3" O.D. round bar weighing several pounds. It seems counter-intuitive to use such large material for such a small part, but it needed a much larger cone base to cover a 2" sq. tube because so much width is lost due to the ~45 degree mitre. I wanted to spread the compression footprint across the entire width of the tailboom tube to the side walls, rather than concentrate all the load at the midpoint of the top wall.
Tailboom compression fitting. Not shown in photos are 2 opposing milled flats on the upper tenon sized to match the I.D. of the airfoil shaped compression strut extrusion. This is where the strut attachment bolt penetrates. The final part only weighs a couple of ounces yet it began as a 3" O.D. round bar weighing several pounds. It seems counter-intuitive to use such large material for such a small part, but it needed a much larger cone base to cover a 2" sq. tube because so much width is lost due to the ~45 degree mitre. I wanted to spread the compression footprint across the entire width of the tailboom tube to the side walls, rather than concentrate all the load at the midpoint of the top wall.
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Brian Jackson
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The geometry gets real interesting where the airfoil compression strut meets the fitting at the tailboom. Allowing .090" separation at all points between strut and fitting meant the clearance notches would resemble an inverted Nike logo. Since this was 3D modeled I could extract a flat pattern to print and glue-wrap around the tube to get the exact shape. I used a vice and clamp to secure the motor section of a small router in midair where I could carefully slide the tube, rather than trying to keep the tool square with the part by hand. A couple of stainless brackets and wooden wedges allowed me to have a mechanical flat on the tube to keep it square and wobble-free while carving.
The geometry gets real interesting where the airfoil compression strut meets the fitting at the tailboom. Allowing .090" separation at all points between strut and fitting meant the clearance notches would resemble an inverted Nike logo. Since this was 3D modeled I could extract a flat pattern to print and glue-wrap around the tube to get the exact shape. I used a vice and clamp to secure the motor section of a small router in midair where I could carefully slide the tube, rather than trying to keep the tool square with the part by hand. A couple of stainless brackets and wooden wedges allowed me to have a mechanical flat on the tube to keep it square and wobble-free while carving.
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Brian Jackson
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While I'm at it, thought I'd share the axle inserts. These were completed some time ago while the forum was having issues.
While I'm at it, thought I'd share the axle inserts. These were completed some time ago while the forum was having issues.
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Brian Jackson
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Making progress on landing gear. It was time to install the axle inserts shown in the previous post. The first photo shows how I secured the LG strut inside a square tube at both ends with wooden wedges on 2 adjacent sides. There wasn't really a good way to secure a round tube to the saw's miter feed with clamps alone. Not visible in the photo is a mechanical stop clamped to the saw's extendable top at the far end of the tube. This allowed cutting both LG struts exactly the same length without introducing measurement errors.
The 2nd photo shows the initial drilling. I used the same centering trick shown in post #58, with one additional "twist". The tube had already been drilled on the other end for the keel connection insert, and I wanted the new holes to line up exactly with the existing hole. I placed the shank of a long 1/4" drill bit through the existing hole that magnetically held a dial level (upper right in photo). This allowed the tube to be rotated until the bit was perfectly plumb. Since the drill press had already been plumbed and leveled, the two sets of holes were necessarily aligned.
The last photo shows the match-drilling of the axle insert. The astute may notice a change in vices. The heavier one in the last photo was required due to a slight load deflection noticed in the previous one which tended to shift the tube a couple thousandths during tightening. The tiny offset wasn't visible but could be heard as a scraping sound while doing a power-off test plunge of the bit. Also in the last photo you'll see a 1/4" center punch passing through the tube and insert at the first hole. The drill press has a small amount of runout which I didn't want throwing the insert out of rotation during the match drilling. The punch locked it in place. Surprisingly both inserts and tubes are interchangeable, with nearly identical bolt friction though I still have them designated left and right. I didn't expect such close tolerances. I could brag but it's more likely a happy accident, as Bob Ross used to say.
Making progress on landing gear. It was time to install the axle inserts shown in the previous post. The first photo shows how I secured the LG strut inside a square tube at both ends with wooden wedges on 2 adjacent sides. There wasn't really a good way to secure a round tube to the saw's miter feed with clamps alone. Not visible in the photo is a mechanical stop clamped to the saw's extendable top at the far end of the tube. This allowed cutting both LG struts exactly the same length without introducing measurement errors.
The 2nd photo shows the initial drilling. I used the same centering trick shown in post #58, with one additional "twist". The tube had already been drilled on the other end for the keel connection insert, and I wanted the new holes to line up exactly with the existing hole. I placed the shank of a long 1/4" drill bit through the existing hole that magnetically held a dial level (upper right in photo). This allowed the tube to be rotated until the bit was perfectly plumb. Since the drill press had already been plumbed and leveled, the two sets of holes were necessarily aligned.
The last photo shows the match-drilling of the axle insert. The astute may notice a change in vices. The heavier one in the last photo was required due to a slight load deflection noticed in the previous one which tended to shift the tube a couple thousandths during tightening. The tiny offset wasn't visible but could be heard as a scraping sound while doing a power-off test plunge of the bit. Also in the last photo you'll see a 1/4" center punch passing through the tube and insert at the first hole. The drill press has a small amount of runout which I didn't want throwing the insert out of rotation during the match drilling. The punch locked it in place. Surprisingly both inserts and tubes are interchangeable, with nearly identical bolt friction though I still have them designated left and right. I didn't expect such close tolerances. I could brag but it's more likely a happy accident, as Bob Ross used to say.
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Brian Jackson
Platinum Member
Thanks guys. Jake, yes the sharp points of the tension struts are getting rounded off to match the eyelet faces. Just hadn’t gotten that far yet.
Brian Jackson
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Haven't posted here in quite some time but have been very busy. I just haven't uploaded photos of progress because it's a lot of redundant operations and you guys have already seen lathing and drilling. But I did get a new milling machine this week. I've never used one before so will be learning. Didn't originally plan to buy one but for the way I want to do a few of the parts there just wasn't a good way to produce the geometry otherwise. The machine was much heavier than expected and even more awkward to move, but got it set up, did the spindle break-in procedure and ran a test on a scrap piece. Wow... loving this machine so far. Have to invest in bits and proper clamping but even using what I had laying around it did an awesome job. Hoping to finish the remaining pieces for the landing gear soon.
On a personal note I accepted an offer last month for a position in NYC doing engineering and 3D modeling, designing mansions for the super-rich. Great job but demanding hours and a lengthy bus commute. So I've been using the hours in transit reading every post in the Builder's Corner archives in reverse chronological order. Up to 2010 currently. Wish the forum was still that active but thankful so much good information is still there. What an amazing wealth of knowledge. Still can't access it through Chrome on my Android phone but the company provided me with an iPhone that seems to work OK with the forum using the Safari browser.
Will post more photos when there's something interesting to show and tell.
Haven't posted here in quite some time but have been very busy. I just haven't uploaded photos of progress because it's a lot of redundant operations and you guys have already seen lathing and drilling. But I did get a new milling machine this week. I've never used one before so will be learning. Didn't originally plan to buy one but for the way I want to do a few of the parts there just wasn't a good way to produce the geometry otherwise. The machine was much heavier than expected and even more awkward to move, but got it set up, did the spindle break-in procedure and ran a test on a scrap piece. Wow... loving this machine so far. Have to invest in bits and proper clamping but even using what I had laying around it did an awesome job. Hoping to finish the remaining pieces for the landing gear soon.
On a personal note I accepted an offer last month for a position in NYC doing engineering and 3D modeling, designing mansions for the super-rich. Great job but demanding hours and a lengthy bus commute. So I've been using the hours in transit reading every post in the Builder's Corner archives in reverse chronological order. Up to 2010 currently. Wish the forum was still that active but thankful so much good information is still there. What an amazing wealth of knowledge. Still can't access it through Chrome on my Android phone but the company provided me with an iPhone that seems to work OK with the forum using the Safari browser.
Will post more photos when there's something interesting to show and tell.
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Brian Jackson
Platinum Member
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So far so good with the milling machine. There's a lot to learn. Spent a week or so making chips from scraps and cut-offs to see how things behaved. Feel confident enough to move on to some actual parts that have been waiting since being taken off the lathe weeks ago. Pictured is the blank billet for the landing gear diagonal and main strut connection (1 of 2). Sadly, 90% of the material will be removed, leaving only a bracket with a round-bottom milled slot. I began by milling two opposing flats with which to hold and clamp the piece squarely. The bottom of the cone gets removed on a 40 degree plane that passes just above the top of the parabolic curved edge of the flats. It was a bit of a chicken-and-egg puzzle with regards to planning a sequence of operation, as I need to leave some of the flat to clamp the part with in order to mill the slot (the small diameter shaft at the end will disappear with the slot.) Unfortunately I don't see an obvious way to grip the resulting cone for the final milling of the 40 degree plane since the plane is milled past the flats. I will post a rendering of the finished part soon and hope I may pick the brains of those more experienced with machining.
So far so good with the milling machine. There's a lot to learn. Spent a week or so making chips from scraps and cut-offs to see how things behaved. Feel confident enough to move on to some actual parts that have been waiting since being taken off the lathe weeks ago. Pictured is the blank billet for the landing gear diagonal and main strut connection (1 of 2). Sadly, 90% of the material will be removed, leaving only a bracket with a round-bottom milled slot. I began by milling two opposing flats with which to hold and clamp the piece squarely. The bottom of the cone gets removed on a 40 degree plane that passes just above the top of the parabolic curved edge of the flats. It was a bit of a chicken-and-egg puzzle with regards to planning a sequence of operation, as I need to leave some of the flat to clamp the part with in order to mill the slot (the small diameter shaft at the end will disappear with the slot.) Unfortunately I don't see an obvious way to grip the resulting cone for the final milling of the 40 degree plane since the plane is milled past the flats. I will post a rendering of the finished part soon and hope I may pick the brains of those more experienced with machining.
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Brian Jackson
Platinum Member
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Getting there slowly but surely. Noticed some interesting harmonics and bit chatter when I began milling the angled notch. I believe the tip of the part where I started milling was simply too far away from the clamping surfaces of the vice, and the mounting angle only added to the problem. So I did several things to help eliminate this phenomenon, which I eventually did. First I tightened all 3 sets of gibs on the machine to reduce whatever imperceptible play may have contributed. Secondly I sawed off as much of the excess blank from the bottom as possible while leaving sufficient clamping area on the milled flats. This allowed the part to sit lower in the vice, shortening the distance between tip to jaws. I also clamped the part vertically (tip pointing up) to do the first 3/4" slot depth to take out the slope angle from the equation. The initial slot was narrower than the design width so that the inside surfaces could be final machined from the angled clamping position.
The 2nd photo shows the part prior to machining the inside corner radii. Pics to follow when finished. The final part will only weigh 1.5 oz. It's designed to host a 5/16" spherical bearing / rod end. Serves the same function as a standard stainless U-bracket but transfers the landing load along the same axis as the compression strut. The mounting bolt at the front of its "foot" passes through the strut plates, main gear strut tube, axle insert and axle. There is also a small pin at the rear underside of its foot that engages with the upper strut plate to prevent accidental rotation, since the forward bolt is slightly ahead of the compression strut's centerline and contact patch.
The strut plates are being made from a slightly thicker stock than first envisioned, but they are also serving as their own saddle blocks. 2 radiused grooves are being machined into one side of each plate to glove over the main and drag struts. Same effect as a long, continuous saddle bar. Will share photos when I get to that point.
Getting there slowly but surely. Noticed some interesting harmonics and bit chatter when I began milling the angled notch. I believe the tip of the part where I started milling was simply too far away from the clamping surfaces of the vice, and the mounting angle only added to the problem. So I did several things to help eliminate this phenomenon, which I eventually did. First I tightened all 3 sets of gibs on the machine to reduce whatever imperceptible play may have contributed. Secondly I sawed off as much of the excess blank from the bottom as possible while leaving sufficient clamping area on the milled flats. This allowed the part to sit lower in the vice, shortening the distance between tip to jaws. I also clamped the part vertically (tip pointing up) to do the first 3/4" slot depth to take out the slope angle from the equation. The initial slot was narrower than the design width so that the inside surfaces could be final machined from the angled clamping position.
The 2nd photo shows the part prior to machining the inside corner radii. Pics to follow when finished. The final part will only weigh 1.5 oz. It's designed to host a 5/16" spherical bearing / rod end. Serves the same function as a standard stainless U-bracket but transfers the landing load along the same axis as the compression strut. The mounting bolt at the front of its "foot" passes through the strut plates, main gear strut tube, axle insert and axle. There is also a small pin at the rear underside of its foot that engages with the upper strut plate to prevent accidental rotation, since the forward bolt is slightly ahead of the compression strut's centerline and contact patch.
The strut plates are being made from a slightly thicker stock than first envisioned, but they are also serving as their own saddle blocks. 2 radiused grooves are being machined into one side of each plate to glove over the main and drag struts. Same effect as a long, continuous saddle bar. Will share photos when I get to that point.
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Jazzenjohn
Gold Supporter
It appears that your configuration has put the main gear axles somewhat further back than I would expect Brian. I'd keep an eye on the front wheel weight as you progress with your build.