Bubble Dancer carbon v-mount threads?

[ecormier]

I'm trying to make my own carbon v-mount for a Bubble Dancer I'm building. I'm following the plans in the bd_vmount.pdf file. How do I go about making the threads for the nylon bolt?

On my first attempt, I left the nylon bolt in the "pocket" as it cured, thinking it would not bond to the epoxy/flox and leave me perfect threads. Well, the bolt stayed stuck and I had to drill it out. :censored: Should I have used a metal bolt instead for making the threads? Or should I completely fill the pocket with epoxy/flox and drill/tap it after it cures?

[will_newton]

use a metal bolt that has been well waxed or coated with some type of release (make sure the threads still show)

[ecormier]

Thanks, Will. I'll try it with Vaseline. Release wax is on my shopping list.

[SHVentus]

Does anyone sell the V-Mount?

[bruceden]

Just use a metal bolt and coat it well with Turtle wax. Use flox and epoxy, fill the hole part way, and then insert the bolt. Let it cure real well and them use pliers to UNSCREW the bolt. Voia you have perfect matched threads.

[Radian]

Does anyone sell the V-Mount?


Yes, Bud Elder makes them. Contact him here: elderb13@earthlink.net

Radian
www.phflyers.com

[SHVentus]

Thanks Radian. I sent an E-mail.

[ozmo01]

I got the V mount and pod from Bud........Very nice stuff :D

[Neil Stainton]

I sell Vladimir's V mounts too.

http://www.hyperflight.co.uk/products.asp?code=AVA-V-MOUNT

Neil.

[SHVentus]

Thanks Neil Stainton,

Is the Ava mount & the Supra mount the same size (one in the same)? I see that you are in England. That's 1/2 way round the world from me (Hawaii). What would the USD costs be with shipping? Thanks.

[Neil Stainton]

Is the Ava mount & the Supra mount the same size (one in the same)? I see that you are in England. That's 1/2 way round the world from me (Hawaii). What would the USD costs be with shipping? Thanks.

The Supra V mount is slightly larger, and a lot beefier than the AVA V mount.

You can use the web site to calculate shipping. Anywhere outside Europe is a flat £3.95 ($5.60 at current exchange rates). We complain about our postal prices, but I don't know how something can get delivered to anywhere on the planet for so little.

Regards,

Neil.

[ecormier]

I tried with the metal screw and Vaseline and it worked. I had to put the v-mount back in its mold to be able to apply enough torque to free the screw. It made a satisfying little "crack" when it broke free. I suppose release wax would have made it easier to break loose. Anyways, the deed is done and the nylon screw threads in nicely now. :)

Thanks again for the help. I'll post pics of my handywork later.

[SHVentus]

Neil,

I punched everything in & got a total. I tried to call to give my CC#, but the line was busy. Then I checked the time zone conversion & it said it was 11:50PM in GB - :eek: Guess no one is there, huh (daa). Can I print out my order & send a USPS MO or would you prefer my CC? Thanks.

[ecormier]

Gentlemen, can you please take your sales correspondence somewhere else? The topic of this thread was me asking for help on making v-mounts.

EDIT: SHVentus, I see you're new here. If you'd like to correspond with Neil personally, click on his avatar (picture), and you'll see his member profile page. Scroll down in this page, and on the right-hand side you'll see a link called "Send PM to Neil Stainton". This link will allow you to send a personal message to him. To check your private messages mailbox, look at the top right section of this website where it says "Welcome, SHVentus". You'll see a link called Private Messages. Click on that and you will see your private message inbox, which works much like an email inbox. I hope this helps.

[SHVentus]

ecormier,

Sorry, didn't mean to micturate in anyones Cherrios. :o ;)

[ecormier]

Hey, sorry for getting a little b*tchy there, hehe. :o

I've attached pics of my v-mount hack-job, er, handywork.

The parts were made using 5.7oz carbon cloth, using half the number of layers as specified in the plan. The hinge pin is a piece of .032" music wire I already had on hand.

I couldn't figure out how to build the platform with pin lugs, so I decided to try the slot approach as shown on the Allegro home-brew v-mount plans:
http://charlesriverrc.org/articles/allegrolite2m/allegrolite_homebrewvtail.pdf

I'm not sure how I should secure the metal pin to the platform. Stitch it there with Kevlar? Or apply a patch of fibreglass? I'd prefer not to poke any more holes in the platform. I'd also like to let the metal pin span the whole width of the platform since the pin only weighs 0.1g .

[Badger]

...

[GaryO]

Looks like you almost have it nailed!

I think there is a thread in the hlg forum about making v mounts, or maybe it's part of the SG thread. A search should find it.

Basically, the wire mount is formed when the platform is molded, with a piece of wire imbedded in it. It's then removed, slotted for the v mount and reinserted. But I think there is a pretty good description. If that doesn't work, PM me and I'll refer you to a friend who makes them for hlg's and has all the problem solved.

By the way, Mark Drela said that it's important to use a wire brush in a Dremel to burnish the threads in the steel bolt when potting the threads. They come loose much, much better. Well waxed, of course.

If you think it's too wobbly, it probably is :)

[ecormier]

Gary, is this the HLG thread you were referring to? http://www.rcgroups.com/forums/showthread.php?t=690276

I also found this thread: http://www.rcgroups.com/forums/showthread.php?t=778239 . It seems he embedded the hinge pin in the CF layers, and slips the v-struts on from the outside. This idea seems simpler than making slots in the platform.

For now, I think I'll stitch the hinge pin on with Kevlar. After finishing the rest of my BD, I might re-attempt another v-mount with an extra CF layer and an embedded hinge pin.

[GaryO]

Those are both good threads, actually I was thinking that Russ posted his v mount build. I'll email him and ask and get back to you.

[GaryO]

Hi,

I was just looking at some info on Drela's v mount. It looked to me like he used 3 layers of 5.6 cf plus some additional around the hinge pin. Mark really engineers that stuff to minimum tolerances. If he said 3, then that's probably the right amount. Not 2 layers of 5.6 and one layer of 5.5 :)

[ecormier]

Thanks, Gary. I can't find where Mark mentions using 5.6oz, but I'll take your word for it. That explains why my v-mount felt a little flimsy.

[GaryO]

Hi,

Here is some build info on v mounts. http://www.rcgroups.com/forums/showpost.php?p=4695494&postcount=503

I thought this might be Mark's v mount info, but maybe not:
http://charlesriverrc.org/articles/allegrolite2m/allegrolite_homebrewvtail.pdf

Here is Mark's info from the Bubble Dancer website on CharlesRiverRC site:]
http://charlesriverrc.org/articles/bubbledancer/PDFs/bd_vmount.pdf

There is also probably more info on the Yahoo Groups Allegro forum.

Gary

[ecormier]

I've made another v-mount using the approach in the SG2 thread GaryO referenced. This time, I embedded the hinge pin in the corner between the platform and the fence. I cut slits in the platform for the v-struts so that it won't jiggle left-to-right. I also added an extra layer of carbon and made the layup a little wetter with epoxy. It doesn't feel flimsy anymore and the weight only went up to 3.1g. In my first attempt, I halved the number of layers in the plan and rounded down. This time, I rounded up.

Now I have one last little problem, but I'm pretty sure it's fixable. After shaping the tips of the v-struts and horn, and poking holes into them with a needle, the carbon layers started to delaminate at the tips (see pic). What I think I'll do is soak the tips in epoxy and wrap an outer layer of glass. I'll leave the tip layup very wet and saturated with epoxy. The tips will be clamped down in the mold while they cure. I'll also leave the pins in the holes so that I don't have to stress the tips again by poking. Please let me know if you have better ideas.

I think I could have avoided my tip problem by leaving the tip layup very wet (no patting with paper towels) and by poking the pin holes with a needle (and leaving the needle there) before it all cured hard. Ah well, live and learn.

Making only one carbon v-mount is not worth the trouble at all. :eek: But when I started my BD, I had set a goal to scratch build as much as possible. I made my own boom, pod, ribs, webs, spar caps, and v-mount. When I'm done, my BD will be something I can be proud of -- and hopefully not something I'll be too worried to fly because of all the effort put in to it. :D

Thanks again to GaryO and will_newton for the help!