1/2 Size KyKo Hot Air Engines

[Jasonb]

A very good result as always Dave.

[Dave Otto]

Thanks guys, I appreciate the comments.

Dave

[pirmin]

that is master sheetmetall work ! realy well done !

[Dave Otto]

Thanks Pirmin!

Dave

[Dave Otto]

Hi Guys

The next items for the fan to be made are the parts that hold the lower shelf into the legs.


Here is a section view of how these parts fit together on the original, I made a small change and added a spacer between lower shelf and the spring clip. This gives the foot a more solid surface to tighten up on and keeps the spring clip from being deformed by over tightening.


The spring clips were patterned after one of the originals as seen in the photo above. They were cut from .015” 301 half hard stainless steel which is quite springy.


Here is a view of the other side.


When creating short little folds, sometimes it is beneficial to leave the tab long and cut it off after bending.


The feet were turned from Delrin and the spacers from steel.


This photo shows how the shelf fits into leg.


The spacer is added.


Then the spring clip.


And finally, the foot.


This creates a rather solid assembly. The small hole on the other end of the spring clip would normally get a rivet to retain the clip. Because you must bend the clip to remove the shelf, I chose to use 0-80 round head brass screws instead of rivets. This way it can be disassembled with out damaging the spring clips.


This all came together nicely.


Here is a family shot of the mostly completed stand. There is an aluminum panel that fits into the two front legs and some special hardware to retain it. The Sharpie marks are used to help me generate the profile of the panel.

Thanks for checking in, more later.
Dave

[Kim]

That's some fine sheet metal work, Dave! 

That looks like a very stable base for sure!

Kim

[pirmin]

Very Nice Work ! Hope we can soon see the whole thing up and Running 

[cnr6400]

  Top notch sheetmetal! 

[Dave Otto]

Thanks guys, your comments are appreciated.

Dave

[Dave Otto]

Hi Guys
Continuing with work on the base for the fan, the next item on the list is the front shield and related hardware to retain it. Studying collected photos and my original fan it is easy to see that there is more than one version of this hardware. Basically, it is a pair of U-shaped brackets inserted through the shield from behind then metal clips and knurled nuts added from the front and finials to dress up the ends of the threaded rods. I have seen the finial as a simple round ball and the one that I chose to model is more like a stack of 3 little doughnuts.
The purpose of all this is for easy knockdown for transport and or shipping.

These parts all ended up being rather small and fussy, but that is part of the fun, right?


Here is an image of what the hardware looks like on an original fan. As you can see the upper clips serve to hold the cage against the stand. It is rather flimsy and can use all the help that it can get.


To generate the profile for the front shield, I used a Sharpie attached to my height gauge and scribed a line at 1” intervals. Then measuring the inside dimension at each line and adding extra to allow for the shield to tuck in behind the legs the curve was created. Only one curve was created and then mirrored for symmetry.


Here is the shield off the laser, the top was clearanced to fit around the tops of the legs. The holes for the U-bracket and name tag were also added.


Not much change here, the shield was carefully curved using my small slip rolls to match the curve of the legs.
I worked on the finish with wet or dry sandpaper and Comet cleanser, I want to figure out how to generate a completely uniform and matte finish, any ideas?


There is a small clip that holds the top of shield against the inside of the upper platform. It is shaped to only contact on the curve and have a nice lead-in to help with inserting the shield. I patterned this using the one on my full-sized fan as a guide. After designing the clip and creating a flat pattern, some blanks were cut on the laser. This is .024” galvannealed material.
The first fold was precisely put in using the press brake then 3D printed tools were designed and made to create the rest of the features.


The clip is added to the platform and retained with a single copper rivet.


Here is a photo with the shield in place.


To make the finials, a form tool was made 01 tool steel (gauge plate). Here the form tool is used to face the end of the stock.


Then drilled and tapped #1-72.


Then the form tool is brought in to create the profile.


My original intent was for the form tool to cut the part free from the stock after forming the profile, but the tool pressure was too great, and the part would break off before the profile was completely formed. So, I ground that part of the tool back a little bit and just cut the part free with a small hand saw. The finials were then screwed onto a threaded mandrel and carefully faced to length.


The U-brackets were made from 01 tool steel. McMaster Carr has a good selection of decimal sizes that come in handy for this sort of thing. This stock is .072” and threaded #1-72. A couple of test parts were made to determine the stock length, so they were the correct size after bending. I used my Di-Acro #1 bender to bend them.


The clips were a similar process to before, laser cut blank and formed using 3D printed tooling. There was considerable work to the to the blanks using a Scotch-Brite wheel to round and blend all the edges before forming.


Here are the U-brackets, nuts, and finials. I didn’t take any process photos of the nuts; I did grind up two form tools to create the shape on each end. The bottom end was formed first after knurling, then drilled and tapped. Then the dome was cut, and the nut parted off with the same tool. The nuts were then screwed onto a threaded mandrel and polished up.


Here is everything assembled.


And a rear view.


And finally, a closer look at the finished hardware, I’m pleased with how it turned out.
Now it is time to start thinking about fan blades and the cage.

Thanks for checking in, more to come.
Dave

[Sanjay F]

That's all looking very nice, the smaller items look pretty much perfect! Amazing

[Kim]

Beautiful work, as always, Dave! 

I'm sorry your initial form tool didn't work the way you were picturing it, but it's somewhat comforting to hear that even craftsmen like you sometimes have to change their plans.

Thanks for the update.  You're going to be done with this soon, then have to come up with another project!
Kim

[Jasonb]

Looking good as always.

Would bead blasting be an option for a uniform matt finish? Though it looks good in the last two images.

[Dave Otto]

Thanks guys!

Kim; maybe my description wasn't very good or clear, my intent was always to put the first fold in using the brake. This is what located the blank on the lower part of the tool. The tools only job was to put the curve and little jog in. This was kind of a quick knock it out kind of a part that I had procrastinated about too long. I only needed one piece and it is pretty much out if sight.

Jason; bead blast maybe, but I can give it a try but I would really like to create a  surface that is matte and has no texture.

Dave
 

[Dave Otto]

Would bead blasting be an option for a uniform matte finish? Though it looks good in the last two images.

The originals were painted with some sort of silver paint, with a brush. There is also a logo that gets stenciled on and I'm thinking that if I can create a surface that I like I will just add the logo to the bare aluminum and not worry about the silver paint.
I will give using Cermark on the C02 laser a try for adding the logo. Playing with power settings one might be able replicate a faded vintage look.

Dave