APE - Space Cowboy fin sets

I've been working on these for a while and I think they are ready for production. A set of three will be $80 shipped in the USA.

They take a lot of machine time to produce so production will be slow, probably only 2-3 sets per week with my limited free time.

They are a slightly different shape and slightly bigger than the fins Badd Azz produced, but according to Jim Hendricksen who came up with the design they have more taper and thinner edges.

The fins taper from .125" to .060" top to bottom. The edges should be .038". The milling passes are .025" wide so each step is around .0004". They feel smooth front to back. Top to bottom you can feel the steps a little. It's nothing that a mill file or some 400 grit couldn't take care of. The edges need to be filed to a sharp edge too, but it only took me a couple minutes to clean this one up.

They are now available to order.

Click here to order: APE-RC 54mm Space Cowboy Fin Sets

Thanks,


Chris





Badd Azz fin on top of APE fin.


Badd Azz fin on left, APE fin on right.

You are correct, I didn't make them to print. I made them the way I felt was best. I felt 0.03" was to thin to hold up. I rather be thicker and not as prone to edge chipping. Good Luck.

Thanks Eric.

We'll have to get them field tested and see how they hold up.

Rock on Chris.

Thanks Eric.

Eric1 said:

Rock on Chris.

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I made a couple changes to the design and machining parameters this week. I reduced the height of the .125" rectangular section at the base of the fin from .250" to .125". I also made the ramp smoother from .250" long to 1" long front and rear. They should completely disappear under your fillets. I also decided to make the fins about .010" thicker overall so they should be stiffer, easier to machine and the finish will be more consistent. I've updated the specs in the first post.

At CWBullet's request I will also be cutting 1/8" lite ply fin guides to go with the fins. They will be $20 shipped when added to the cost of a set of fins. Great idea Chuck!

I've added these to my webstore. I added a link in the first post.

Thanks!

Nice job. I can't wait to compare them to the originals.

I cut three sets of fins yesterday. The first set will ship tomorrow.

I'm still waiting for the end mills I need to cut the fin guides. They are coming from about 20 miles away, but the seller and USPS are taking their time getting them here.

I ordered a set. I am excited. Now all I need is some flying time. Schedule with my kids is rough!

Any chance at a run of 75mm?

Yes, there is. If you assume they grow 50% in each direction they'll take ~3.3x the machine time to machine. I'm thinking $225 a set.

I'm still catching up with the 54mm orders, but I could get a set of 75mm cut in the next couple weeks.

prophecy said:

Any chance at a run of 75mm?

Click to expand...

Received my fins today. They are very nice indeed! And quick shipping!

Thanks Chris!

NikeMikey

Thanks for the feedback Mike.

BTW: I heard back from the vendor I bought the tooling for the guides from today. Apparently he sent them to the wrong address so he sent a new package yesterday. I should have them by the weekend.

Have you thought about 98mm or 75mm diameter rocket fins?

cwbullet said:

Have you thought about 98mm or 75mm diameter rocket fins?

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I asked about it earlier in the thread. Seems like machine time increases exponentially with surface area and it's cost prohibitive. By my count a 98mm set would be in the $400 range, when each of my min dia 4" builds have cost less than that for the whole build (and around $20 in G10 for the fins). Totally understand the time required to make them and that time is money - but it probably just isn't feasible from either end.

I read the thread. Sorry, I missed that post.

I read somewhere that Eric charged $225 for 75mm and $475 98mm sets. I can't find those posts now of course. That's cheap for the amount of work that went into them.

You have to scale all three dimensions by 150% to make a 75mm fin. 1.5^3 = 3.375.

I've had 3-4 requests to make them, so I'll look at it soon.

Bandman did a nice set for under $200 i think

Kenny

I took a look at a 75mm fin. It looks like I could do them for about $175 a set.

They'd be 10.85" at the root and 3.85" span. They will be .187" thick at the root and .090" at the tip. The edges will be .060".

Let me know if you're interested.

Very nice fins. Just wondering how many flyers will pay $400 just for a set of fins?

I might be interest this summer. Right now, I am not.

I could not afford $400.

I guess you're referring to the 98mm sets. There are always guys that want the very best and are willing to pay for it.

I can't even afford to fly 75mm motors, let alone 98mm.

Chris,

Do you use a CNC to make the fins?

Yes. There's no other way you could do them.

Which one do you own?

I have had a business selling RC car parts and tools for about 5 years. For the first 3 years I farmed out most of the parts I sold. After a couple years of dealing with missed deadlines and broken promises I decided that I wanted a CNC machine of my own. I had a Taiwanese lathe and mill/drill. I sold those and had just enough to buy a Grizzly G0704 and convert it to CNC. It was quite a project. I bought a CNC conversion kit that had the stepper motor mounts and ballscrews. I had a local machine shop add oiling grooves to the carriages. I built a controller (twice) from purchased components. I converted the head from gear drive to direct belt drive, upgraded the motor from 700w to 1100W, etc.

It isn't an industrial grade machine, but it's pretty reliable, produces decent parts and IT'S PAID FOR. It just takes longer than a purpose built CNC machine. For cutting G10 and using smaller milling cutters I could really use a faster spindle.

I cut a couple more sets of fins today. They need to be trimmed off the sheet and they will be ready to ship.

Got my set last week. Looks great. I am excited. Now to find some time for rocketry.