Boom Furler issues

[ronstory]

Originally Posted by Lodesman

I would think it would have been die-cast - and if it's not weldable, it could probably be used as a plug for investment casting (lost wax) a replacement.

The surface didn't (to me) look as smooth an die cast and I didn't see any injector pin marks when I zoomed in. Not to mention, pattern making for a die cast is *way* more expensive... great if you want to make *lots* of parts with a high tolerance, it's the way to go. Not sure volume of Hood boom furlers but I would only do die casting if I needed the tolerance or planned to make more than 10K volume.

My two cents.

[a64pilot]

I am surprised that it’s aluminum, but even where it looks to have had a piece broken out, it’s still black, that had me thinking it was a fiber reinforced nylon or something.
However I believe it can be welded, that it broke being subjected to forces that it doesn’t usually see in use, maybe after it was removed or something or during removal.
However as an old Welder I could easily take a plate and weld two ears on them and saw off the old ears with a band saw and drill it, install helicoils and bolt on the plate with the two ears.

But I’d give welding a try first. I think it will be weldable and you can always go back to the bolt on a plate idea later if welding doesn’t work.
Try to find someone to anodize it after welding too, when you weld aluminum and anodize it, the welded sections turn black if you try to anodize a different color.
But anodizing will hold up over time, paint etc won’t.
Welded well and cleaned up with a Dremel and you won’t even know it was ever broken.

[ronstory]

OK, curiosity took hold and I took a closer look... and am now puzzled.

The back side with gear has a waffling on the surface (to help release) and looks to have die pin marks on the back.

However, the front with the forks, the forks definitely looks sand cast and the relief in the forks has surface would not work in a die.

I would still take it a god-like welder and see what they can do.

[groundtackle]

a64pilot,
It's always tempting to weld things like that but I wouldn't touch it. So much prep is required to get back to clean then at the end it starts cracking, grrr.
A quick tig hit on a clean location will tell you immediately the trouble coming your way. In a pinch sure, ugly mig the heck out of it to get home.
Chris

[groundtackle]

Ronstory, pretty sure its sand as you say. I always thought that graph paper look was a simple cheater way to finish a surface. Even if the casting comes out rough it still passes.
I could be wrong and happy for a foundryman to educate me.
Chris

[Lodesman]

Originally Posted by ronstory

However, the front with the forks, the forks definitely looks sand cast and the relief in the forks has surface would not work in a die.

I would still take it a god-like welder and see what they can do.

I'm no expert, but with the relief in the forks, how would the plug be removed from the sand mold? Could it be sand-cast forks welded to a die-cast geared cup?

I can't see how that is weldable - it looks like the metal has deep fracturing from back to front. Perhaps it could be brazed (though I have no idea if that's feasible or how well it would hold up).

[a64pilot]

I think what will determine it’s weld ability is the series of aluminum it’s made from.
I hope it’s 6000 and weldable, 6061 is very often used, it’s strong and very available. If it’s 2000 or 7000 then it’s not going to weld well, especially 7075, which I’ve seen someone weld a table out of that worked, but it’s supposed to micro fracture and be a weak weld that’s likely to break, but the table worked fine.

[Eigenvector]

Originally Posted by Lodesman

I'm no expert, but with the relief in the forks, how would the plug be removed from the sand mold? Could it be sand-cast forks welded to a die-cast geared cup?

I can't see how that is weldable - it looks like the metal has deep fracturing from back to front. Perhaps it could be brazed (though I have no idea if that's feasible or how well it would hold up).

Weldability comes down to the grade and sulphur content. Many times sulfur is added to increase the flowability to get details (like gear teeth)


By ignoring the yoke holes and the ear reliefs. Sand cast and bore holes and die grind reliefs later.


Lost wax casting would result in all the features but you'd have to generate the wax plug. Not sure, but there may be a rapid prototype material that you could bake out of the ceramic mold once modeled up.



The other unknown in this part is how the shaft is restrained in the hub. I don't see a keyway. I'd hate to think it's a jacobs taper. Maybe just a straight press fit.


If that shoe was on my foot I'd chuck it up on the lathe and part that gear off. Put in on the mill and put a back side step and around 24 6mm tapped holes in it. Machine the ears and hub in one shot from a block of 6061 (it's not that big). Bolt is together. But I have the equipment to do it, including the welding side so labor is nil. The welding would probably be ok, but I know the machined part is good (assuming it weldable).

[Tudorsailor]

I have no idea if this helps, but are you aware that Hood spars who made Stoway furling main became Formula Spars and continued to make furling in-mast systems for Oysters until recently. At one point they were based in Holland and then moved to Ireland. Then I think they returned to the UK. The only website that I can find for them is https://compositesuk.co.uk/hub/organisation/1455 If you think that the same Hood that made your in-boom furler as made the in-mast system then you might contact Fox's Rigging in Ipswich to ask their advice?
TS

[doublebubble]

We certainly appreciate all the advise and did find a small workshop that was willing to repair it (weld ), it's come up looking ok, beefed it up a bit as well, going forward we will have the gear section machined off and fabricate a new one out of stainless, press fit the gear section into it and grub screw it, for now it's back on and working, I'm pretty sure it started with a few accidental jibs putting undue force on the yoke resulting it being cracked.

Kind regards Rod Lewis.

[groundtackle]

Abide, haha. I couldn't agree more on your repair method. You use metric in Texas now? Welcome and please tell the others. They probably cracked it smashing the casting on the shaft at the "factory". Maybe a set screw or pin hidden in pic but a key would be smart. Treat this whole thing like prop shaft coupling.

DB, excellent news and we all appreciate when folks come back and tell us how the issue is progressing. Post pics.

Electric winches have also been very good for us in the marine industry, we see lots of gear proof tested..
Chris

[groundtackle]

so ah... there I am teasing Eigenvector about the metric system, oops.
I just spent 2 hours learning something about vectors.
I think latent vector is a great handle for me now and should have stayed in skool.
Chris