Straightening Prop Bores

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jetpack

Well-Known Member
Joined
Feb 2, 2007
Messages
562
I have a prop where the bore is way off on it in relationship to the blades and I would like to try and save it. Any methods around? It's an 1/8" bore.
 
I guess the better question is how to fixture it up after the bore is filled so it can be re-drilled? I was thinking epoxy and a block of aluminum to drill into with the mill. Heating it up to kill the epoxy but that can be hard work.

I'd send it back to Dumas but I don't think they would honor me buying it off eBay second-hand, only from them and they discontinuted it long ago. It's a prop for my Cox .09, about the only promising metal prop around for it so I'll have to try reworking it or scrapping it out...lol.
 
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I guess the better question is how to fixture it up after the bore is filled so it can be re-drilled? I was thinking epoxy and a block of aluminum to drill into with the mill. Heating it up to kill the epoxy but that can be hard work.

I'd send it back to Dumas but I don't think they would honor me buying it off eBay second-hand, only from them and they discontinuted it long ago. It's a prop for my Cox .09, about the only promising metal prop around for it so I'll have to try reworking it or scrapping it out...lol.
Drill it oversize and then turn a piece of brass down that is size for size or maybe .001 press fit , press it in and drill it back to the original size.

Good luck , Tim K
 
I guess the better question is how to fixture it up after the bore is filled so it can be re-drilled? I was thinking epoxy and a block of aluminum to drill into with the mill. Heating it up to kill the epoxy but that can be hard work.

I'd send it back to Dumas but I don't think they would honor me buying it off eBay second-hand, only from them and they discontinuted it long ago. It's a prop for my Cox .09, about the only promising metal prop around for it so I'll have to try reworking it or scrapping it out...lol.
Aluminum is much softer than Copper Be so the drill bit might not go in straight. Having said that, I think Dumas props are cast from a different alloy and I do not know how hard the material is.

I had a prop with the same problem. It was a JG prop...going back to the 70's. I ended up using a needle file to "center" the hole and then sleeve it with a section of 3/16 K&S tubing. Depends on how much material you have in the hub, and how much is the hole off, this may work.

Good luck.
 
Dave, with you being a machinist and lathe operator I thought that if anyone could figure out a way to repair it, you could! :)

What size is it? I might have one in an old box of junk.
 
The only way I can think to fixture it is to use epoxy putty and indicate it the best I can. I just don't really know the best way to hold it to re-machine it. :blink:
 
I gave them an email, we'll see what they say.

I am sure the spatter might have had something to do with this.
 
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That spatter actually looks like small bubbles in the ceramic slurry that makes up the mold. I'm sure that the OEM has a master fixture that locates off of the blade face, so the spatter would definitely affect the set up. The prop should have been scrapped before machining due to the casting defect.
 
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Since it is a prop that has been discontinued we would not be able to offer any sort of replacement. Thank you,

Customer Service

Dumas Products

Looks like I'll be trying my hand at bushing a prop...lol.
 
Yeah Dave i think your best bet is to drill it out and bush it back down to 1/8 with brass tube.
 
That I can swing, its getting the prop in the mill is whats stalling me out. I guess epoxy putty and a tooling block to glue it to for the vise.

The putty would allow me to indicate it in as it sets. Some mold release on the prop I suppose,

Let it cure and hope for the best with a couple of light clamps on the blades when its time to centerdrill.

Don't know, is that how its done?

Has anyone ever seen a prop fixture before??? Post a pic so my headbone doesn't hurt. What would hurt is to say its junk. I'd like to pick the garbage around here. :lol:

Believe it or not, this is a straight on pic of the prop just so you can see it is way past working the blades to correct.
 
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