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Peening beads
Hi there,
I wasn't thinking of peening the beads, I'm not too familiar with the process and I don't have any mechanical means, I guess I could use some sort of pointy hammer or punch system though. Being a builder i am reasonably accurate with hammers and blunt instruments. I am hoping that I can hold the blades firmly enough with the jig to place a few decent tacks each side of the blades before I finish weld.
In saying that if this fails I will try other options.
I will be welding in about three days when things slow down a bit and will let you know what the outcome is.
Cheers,
Glenno
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Are you stick welding it or are you using a tig torch? If you have access to a tig torch go for it , it's a lot cleaner, you can control the arc and the heat better.
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Welding blades on hub
G'day,
I am stick welding. Done plenty of stick with normal steel and also mig set up for alluminium (built a alloy boat as well) I am also competent with brazing. Unfortunately I have not had much of a go with tig, I would love to become competent using tig, can you get the volume of weld on with tig as well as with stick?
Cheers,
Glenno
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I tack each side of the blade a few times before removing it from my jig to weld 'em up. So far, no distortion.
A MIG would also do a good job and is cheaper to buy than a TIG. Can you borrow one?
Jeff
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With stainless you need to know exactly what alloy you're working with, and choose the rod accordingly, the right number, the right suffix, etc. (Read the catalogs; I wouldn't make any recommendation here, this project is your baby!). It certainly is possible to make an acceptable stick weld, but if you aren't sure you can, you better practice on scrap, trying out your settings, your root gap, and so on. You'll want good long run-in and run-off tabs at either end of the joint so the arc is well established before it gets to the prop and after it comes off the end. Then when you cut off the tabs and grind the prop hub flat at either end, hopefully you won't see porosity and voids in the ends of the weld. Naturally you'll want to have the weld positioned as near to the flat position as you can (which is a trick given how the blade wraps around the hub!!).
Look up shot-peening. Somebody near you probably provides this service, well worthwhile in the interest of not slinging off a blade, I'd think.
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Welding sticks
Hi there,
I know the hub is 316L but I'm not too sure what grade the blades are, they are off a 25hp omc stainless prop. I have 316L rods here in 2mm and 2.5mm, I did a small tack weld and it was really on, had to bend blade back and forth with force a few times before it came off.
Do you think the 316L sticks will be ok?
Keep in mind only 10 to 15hp will be driving this prop.
Cheers,
Glenno
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That should be no problem at all--my props have to handle 70 hp. I use a carbon steel hub and stainless blades, with carbon steel welding wire (which makes clean up of the welds easier). The plan is to get a prop I'm fully satisfied with powder coated. So far, I'm still playing with them so....
Jeff
PS: I wonder if Ron Hill started this way...
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tig is affordable if you already have an dc welding machine, all you need is a tig torch, flow gauge and a bottle of argon gas and you just reverse the polarity, no switch on your welding machine! No problem, reverse the cables, your ground becomes your torch and your stick becomes your ground. If you can weld with an oxy and acetylene torch with a coat hanger you can weld with a tig torch. As for the material they used in making the prop you got your blades from, it's probably in the 400 series stainless and I know Ron is your best man for that question.
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I see that part of my suggestion above might not apply, the part about run-in and run-off tabs, because maybe you have that if your hub is a lot longer than the blade roots. I'm having a little trouble thinking about your project without thinking about an idea I had for turning old 2-blade racing props into 3- or 4-blade props; This would require sectioning cuts through the hubs of the donor props and then welding the hub edges. That would call for run-in tabs for sure, and some other tricks.
I think I understand from above that you are V-ing the blade roots to a point, for max penetration. If so, try to get the first pass on one side to penetrate clear under so that you see weld metal protruding all along the other side. With a little abrasive wheel in your Dremel motor, grind that protruding metal down until you have an unbroken length of solid metal to get your Side B pass to hook to. You don't want voids under the blade roots, preferably.
Good luck on it. I'd ask OMC about the alloy, or Ron. And I'd get the weld areas shot-peened regardless of horsepower.
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Home made prop
Hi there,
Sounds like shot peening is a good idea, does the process make the welded area more maluable and less inclined to crack?
And I will try to get no voids under weld foots.
I do like the idea of run in for the welds to bring the heat and penetration up to an even level for the entire length of weld.
Originally I was just going to weld the blades on with no v at the foot, lucky there are knowledgeable people here willing to help.
Thanks for the help so far!
Cheers,
Glenno