Prop re-pitching and casting.

[Terry Keeley]

All you need now Terry is an Induction furnace!

With a built in vacuum casing machine! That's how they generally do Platinum and why it's so expensive to get done!

 

[lohring]

Chrome cobalt alloys like those for partial denture frames should work well for props. I believe that alloy has been used on many commercial record setting props, especially for high power electric motors. I ran one on the gas scale boat that Kelly Gruol drove to the 2 lap record. The local dental lab in my area uses a vacuum melting and casting process. The centrifugal casting machine you have was used years ago but should work with the right alloy and an inert gas shielded torch flame. Find a lab in your area and see what alloy they use. My local lab quoted $80 to cast a prop from a furnished wax pattern. Brass & bronze alloys will cast a lot easier, though. One of my classmates used an ox/acetylene torch with a centrifugal casting machine to cast jewelry from brazing rod .

Lohring Miller

Thanks Lohring, that's what I suspected. I did get a couple props cast in CoCr but wasn't happy with the finish on the bore or the drive dog, that's why I'm leaving mine solid and will finish after casting. That and CoCr is hard stuff! Regular tools don't touch it, you need diamond! $$$

I'm going to try one of the heat-treatable stainless steels that can get to a tensile strength of 210,000 psi, every bit as strong as most CoCr alloys but more workable.

I started this hoping a jeweller could do it, but, it's getting complicated so I decided to bring it "in house". The alloy I'll try melts in the 2600F range so that's quite a bit more than they're used to when casting silver and gold. Platinum is a little higher at 3200F but jewellers that do it are "high end" and expensive. The equipment I'm going to use is all rated for Platinum so hopefully it'll work well.

ps: I just looked at the properties of those dental alloys and this SS "as cast" will be stronger...

Chrome cobalt is tough. I use diamond burs to cut it as well. I would never try to drill a seriously accurate hole in it. I would expect the same problems with stainless steel alloys. The advantage of the newer dental chrome cobalt alloys is that they can be bent without breaking.

You can get an accurate bore in your prop castings with a ceramic core. You could try molding one in your investment material using a convenient size of tube with some oil or other mold release. A wire in the middle would help with strength. Slitting the tube might be necessary.

Lohring Miller

 

[Terry Keeley]

Well after a break I'm back at this little project, I'm at the point of trying to melt some 17-4 stainless steel which needs about 2600F. Doing a little reading I saw that an oxy/fuel torch wouldn't cut it, also the flame can contaminate the melt apparently.

Industry uses carbon rods in a furnace, the plasma "flame" produced is somewhere north of 9000F. A little more digging and I discovered carbon arc rods that are used with a "carbon arc gouging" torch. Apparently pre WWII they used to do a lot of brazing and even welding with carbon arc torches. Ken Retallic here suggested I try carbon arc rods also, thanks Ken!

 

[Walt Barney]

Well after a break I'm back at this little project, I'm at the point of trying to melt some 17-4 stainless steel which needs about 2600F. Doing a little reading I saw that an oxy/fuel torch wouldn't cut it, also the flame can contaminate the melt apparently.

Industry uses carbon rods in a furnace, the plasma "flame" produced is somewhere north of 9000F. A little more digging and I discovered carbon arc rods that are used with a "carbon arc gouging" torch. Apparently pre WWII they used to do a lot of brazing and even welding with carbon arc torches.

Terry,

I did a lot of body work with Carbon Arc in the early 60's on cars that at that time has a lot thicker steel, had to be careful that we did not get to much heat or the metal would warp, and that caused a major problem.

Walt Barney

 

[Terry Keeley]

I think guys still use the torches these days to bend metals, the "flame" (plasma) is pretty intense!

 

[Bradley Ward]

Laser profile the made prop and cnc it!

 

[Terry Keeley]

Got the arc torch and argon working, the melt was much cleaner. I kept popping the dryer breaker so will havta wire in a 50A circuit.

Buddy at the welding shop said this 0-30 psi propane regulator would work to control the gas but it blew an o-ring as soon as I opened the tank. Any idea what I can use to regulate the gas? As I understand it a tig regulator/flowmeter is pre-set at 25 psi which is higher than I'd like.

 

[shoboat]

Terry,

Are you trying to pour the 17-4 Stainless Steel into a propeller mold?

Greg at Voodoo Propeller can make those 17-4 SS propellers for you really

Inexpensive. You do not need Stainless Steel propellers for fast boats anymore.

Jim already makes what you are looking for I believe.

Just Curious,

Mark Sholund

 

[Ken Retallick]

Great work Terry!

Ive never used my carbon arc to melt anything , just a bit of brazing.

There rather bright!

 

[John Beardslee]

Got the arc torch and argon working, the melt was much cleaner. I kept popping the dryer breaker so will havta wire in a 50A circuit.

Buddy at the welding shop said this 0-30 psi propane regulator would work to control the gas but it blew an o-ring as soon as I opened the tank. Any idea what I can use to regulate the gas? As I understand it a tig regulator/flowmeter is pre-set at 25 psi which is higher than I'd like.

Hi Terry

The flow meter is adjustable on my TIG, not sure about some of the newer ones. Mines on a Miller 330. The regulators are built tank pressure specific, flammable gases are at much lower tank pressures like acetylene at 330 psi max where non-flammable gases like oxygen, argon, helium etc. are at high pressure around 2,200 psi. You're probably lucky you didn't have an explosion. I can't some of my contacts to for a used one, I may have a set of oxygen & acetylene Gage's I could sell.

Thanks John

 

[John Beardslee]

Good morning Terry

In the US all flammable gas storage tanks have left hand threads and non-flammable gas storage tanks have right hand threads (I'm not sure about Canada)so it isn't possible to mix things like regulators up. Did you have to modify the regulator to make it adapt to an argon tank? When I said explosion in the previous post I meant blow the face off the gauge, I've never seen it happen but have heard of it but only when someone modified a regulator. I'm surprised that a welding tech person would tell you to use a propane regulator (flammable gas). You probably could use an oxygen regulator from an oxy-acetylene torch but flow rate isn't quite as fine in it's adjustment as a TIG regulator with a true flow meter would me.

Thanks John

 

[Terry Keeley]

Terry,

Are you trying to pour the 17-4 Stainless Steel into a propeller mold?

Greg at Voodoo Propeller can make those 17-4 SS propellers for you really

Inexpensive. You do not need Stainless Steel propellers for fast boats anymore.

Jim already makes what you are looking for I believe.

Just Curious,

Mark Sholund

Gonna spin cast them. Now why would I let Greg & Jim have all the fun?

Great work Terry!

Ive never used my carbon arc to melt anything , just a bit of brazing.

There rather bright!

Thanks for pointing me in the right direction, very impressive you're building motors completely on your own, I may "harvest" more info from you down the road if you don't mind!

Good morning Terry

In the US all flammable gas storage tanks have left hand threads and non-flammable gas storage tanks have right hand threads (I'm not sure about Canada)so it isn't possible to mix things like regulators up. Did you have to modify the regulator to make it adapt to an argon tank? When I said explosion in the previous post I meant blow the face off the gauge, I've never seen it happen but have heard of it but only when someone modified a regulator. I'm surprised that a welding tech person would tell you to use a propane regulator (flammable gas). You probably could use an oxygen regulator from an oxy-acetylene torch but flow rate isn't quite as fine in it's adjustment as a TIG regulator with a true flow meter would me.

Thanks John

It did "explode" in a way, there's a sort of "burst panel" on the bottom that let go, I should go back to that dumbass and throw it at him.

I'm thinking of trying an argon (also called argon/CO2) regulator with a flowmeter like this:

It looks like I should be able to adjust the flow to a simple nozzle, no? I'm a total noob when it comes to welding.

 

[John Beardslee]

Terry,

Are you trying to pour the 17-4 Stainless Steel into a propeller mold?

Greg at Voodoo Propeller can make those 17-4 SS propellers for you really

Inexpensive. You do not need Stainless Steel propellers for fast boats anymore.

Jim already makes what you are looking for I believe.

Just Curious,

Mark Sholund

Gonna spin cast them. Now why would I let Greg & Jim have all the fun?

Great work Terry!

Ive never used my carbon arc to melt anything , just a bit of brazing.

There rather bright!

Thanks for pointing me in the right direction, very impressive you're building motors completely on your own, I may "harvest" more info from you down the road if you don't mind!

Good morning Terry

In the US all flammable gas storage tanks have left hand threads and non-flammable gas storage tanks have right hand threads (I'm not sure about Canada)so it isn't possible to mix things like regulators up. Did you have to modify the regulator to make it adapt to an argon tank? When I said explosion in the previous post I meant blow the face off the gauge, I've never seen it happen but have heard of it but only when someone modified a regulator. I'm surprised that a welding tech person would tell you to use a propane regulator (flammable gas). You probably could use an oxygen regulator from an oxy-acetylene torch but flow rate isn't quite as fine in it's adjustment as a TIG regulator with a true flow meter would me.

Thanks John

It did "explode" in a way, there's a sort of "burst panel" on the bottom that let go, I should go back to that dumbass and throw it at him.

I'm thinking of trying an argon (also called argon/CO2) regulator with a flowmeter like this:

It looks like I should be able to adjust the flow to a simple nozzle, no? I'm a total noob when it comes to welding.

Yup, the two styles either have an adjustable flow tube like this or simply a second gauge that is adjustable for outflow. What size argon tank are you using? Does it have lefthand thread? What vessel are you using to melt in? Graphite? Yes I'd go back to the welder guy and try to get my money back and/or share a few choice words with him. I can pm you some choice US words if you'd like! I don't think I've ever heard them in Canada!

Thanks, John

 

[Terry Keeley]

Yup, the two styles either have an adjustable flow tube like this or simply a second gauge that is adjustable for outflow. What size argon tank are you using? Does it have lefthand thread? What vessel are you using to melt in? Graphite? Yes I'd go back to the welder guy and try to get my money back and/or share a few choice words with him. I can pm you some choice US words if you'd like! I don't think I've ever heard them in Canada!

Thanks, John

Gonna pick one up this afternoon. Tank is an 80 ft3 "Q" style, has regular RH thread. Crucible is silica, made for platinum which melts even higher at 3200F, seems to be holding up so far. Gonna get a leather apron too for safety.

I should get my french sweetie to come in with me, the french have a whole plethora of curse words that would do very well in this instance!!!

 

[Olly]

I have a regular if you want to try it out .

 

[Randy Rapedius]

 

[Terry Keeley]

 

[Ken Retallick]

Your welcome anytime Terry!

Definitely wrong regulator. That one for Lpg/propane is only for low pressure bottles. Argon/nitrogen co2 etc bottles have MUCH more pressure in them.

 

[Terry Keeley]

Got a nice Victor reg/flowmeter and leather apron from my buddy Olly, thanks mate.

Wiring in a 240V/50A circuit today and will give it another shot. Hopefully I don't end up back in 1955.

 

[David Murany]

Man what kind of weed do you guys have in Canada? Hahahaha