Prop hardening questions

Did a bunch of research on prop hardening. Bought a Kiln.

Got two questions yet for the experts.

Is there any preparations to do to the prop before putting in the Kiln? Such as cleaning and or oiling? What cleaner? What oil if any?

And - how should the props be set in the Kiln? Just set them on their blades or the hub? How about stringing a few props on a hub shaft and suspending them accross two points? Is there any potential for distortion?

Thanks for any suggestions you may have.

Doug

Doug,

Some wrap them in a stainless steel bag.

Others hang them across a bread pan on hard shafts.

Just make sure the propellers are clean.

You know it is going to smell up the garage right?

I would suggest a fan to keep the smell down.

Have Fun,

Mark Sholund

Thanks Mark

I didn't consider the smell factor. I got a large storage building I will set up instead of my workshop area.

I'll pick up some drill rod and do the hanging thing.

What is a SS bag and what would the purpose be.

Doug

Doug,

The SS bags are from McMaster-Carr and they must hold the heat better I am guessing.

I only know a few people that use them. Maybe Marty or Norm will let us know how they

harden theirs, they seem to have one of the best recipes for heat treating propellers.

Good Topic,

Mark

Take the raw prop, heat through at 1450F (20 mins or so)

Water quench.

S&B, pitch etc.

Harden at 625-650F for 3 hrs.

The bags are a waste of time, more for doing steel etc.

Thanks for the input Terry.

According to Brush Wellman's "Guide to Beryllium Copper". High Strength Cast Beryillium Copper Alloys (Alloys 275C, 245C, 20C, 21C, and 165C). I understand our props are 20C.

The standard age hardening cycle for the high strength casting alloys, both annealed and as-cast, is three hours at 625-650 degres F. However, to develop the highest strength for the as-cast products, a seperate solution anneal should precede the age hardening.

I am a heat racer and not a Saw guy, and only hoping to harden my props enough to hold pitch for lower rpm applications. I am thinking I need only to do the age hardening (standard age hardening) and not the anneal step. I already have props thinned, balanced, modified and sharpened. In your or others opinion(s) would my one step age hardening be sufficient?

Thanks - Doug

DPeterson said:

Thanks for the input Terry.

According to Brush Wellman's "Guide to Beryllium Copper". High Strength Cast Beryillium Copper Alloys (Alloys 275C, 245C, 20C, 21C, and 165C). I understand our props are 20C.

The standard age hardening cycle for the high strength casting alloys, both annealed and as-cast, is three hours at 625-650 degres F. However, to develop the highest strength for the as-cast products, a seperate solution anneal should precede the age hardening.

I am a heat racer and not a Saw guy, and only hoping to harden my props enough to hold pitch for lower rpm applications. I am thinking I need only to do the age hardening (standard age hardening) and not the anneal step. I already have props thinned, balanced, modified and sharpened. In your or others opinion(s) would my one step age hardening be sufficient?

Thanks - Doug

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Doubt it but what would I know.

You can get the 1450F by heating with a torch in a dark room until dull red, quench then put them in a self cleaning oven.

Looking for a small low cost oven. The one I was using weights a ton has developed problems. Any recommendations?

http://www.amaco.com/shop/product-128-fa-5-e-kiln.html

I use this with a controller I got on Ebay.

http://www.ebay.com/itm/PID-Temperature-Controller-Kiln-Probe-SSR-Relay-40A-HS-for-Paragon-Pottery-Glass-/121094869999?pt=LH_DefaultDomain_0&hash=item1c31d113ef#ht_2269wt_679

Thanks for the input Terry. I'm just trying to get over my nervousness about the annealing step. I got a lot of props to treat. I want to know what I am doing before I do it. Not much shared experience being posted. Either there is not a lot of hands on experience out there and or we have entered the land of secrecy. I'll start by doing some junk box props.

I bought a real nice used Neycraft 9491001 off Craigs List. $100.00 Another

Doug

DPeterson said:

Thanks for the input Terry. I'm just trying to get over my nervousness about the annealing step. I got a lot of props to treat. I want to know what I am doing before I do it. Not much shared experience being posted. Either there is not a lot of hands on experience out there and or we have entered the land of secrecy. I'll start by doing some junk box props.

I bought a real nice used Neycraft 9491001 off Craigs List. $100.00 Another

Doug

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Good score, that's similar in size to my Amaco I got for $150.

You'll get some scale and nastyness after the anneal, that's why it's better to finish after that step.

Don't know why it's not popular to harden props, even with the torch/oven method they come out much stronger than as cast.

They hold their pitch, you can thin them down and sharpen them razor sharp and the edge holds.

Makes a heck of a difference, just ask Mark Stein.

What I used to do, and I did alot of props. My recipe came directly from Brush Wellman in Detroit. Anneal by soaking at 1100Ffor 30min. and quench in water. Heat treat/lprecipitate at 600F for 30min. and let air cool. Note: By annealing your props first the end product will have less chances of heat risers or hard/soft spots that cause stress spot that are created during the casting process. Therefore I never precipitated as cast props. Details: I used an electric atmospheric furnace and hung the props cross ways on drill rod suspended in a small bread tins with notchs on the rim to keep the rods in place. I precooked everthing in the furnace so that nothing would contaminate the hot props or stink up the shop. I used aluminum foil to make a tent over the props and bread tin. Be sure to plan ahead how you will open the foil and transfer the props to the distilled water quench. Don't drop them because they are very soft and even hitting the water to hard can bend them. The distilled water amost completely eliminates crusty surface hard spots which come from the minerals in normal drinking water and will get baked on during the precipitation process . I quenched in room temperature distilled water. Clean/dry the props again and suspend them the same way and retent them and place them back in your furnace that has cooled down to your precipitation temp. Let it cool down with the door closed or if the coils cool to fast they can break. Our props are small and there is no need to soak for longer periods of time unless you want to clean the dust off your electric meter wheel! Some of the annealling temps I've seen here seem way to high to me, I was warned about getting the 2% percent berilium copper too hot as the berilium will perk out and change the chemistry of the material and the fumes are toxic as well as the dust. My phone number is 989-426-3976, feel free to call me and I'd be glad to explain further and clarify/answer any questions you may have.

Thanks, John

I bought alot of Johns props when i lived in Michigan very nice props Robert

The small kiln I posted a link to is perfect for one or two props.

It also only takes about 15 min to reach 1100 deg and takes no more power than a the wifes iron.

The controller holds the temp spot on and it is all very light and easy to store on the shelf when not in use.

This setup makes it possible for any one to do there own props for less than the cost of a new eng.

If you are serious about going fast and keeping the set up constant this is a must have.

Careful on the quenching process- I never liked quenching in water due to the reaction of a HOT piece of metal meeting room temp water. Sounds like John has done a lot and you should call him and take his advice

I have bin using 10w non detergent oil for the quench.

dwilfong said:

I have bin using 10w non detergent oil for the quench.

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Probably less violent than water quenching but still the oil may ignite. Years ago the owner of a machine shop I worked at asked me to make a special two flute end mill from drill rod with a one inch radius cut on the sides. Once the machine work was done the drill rod needed heat treating. Heat until red and drop it in that can filled with motor oil. O.K. Well the motor oil caught fire and a young helper who delivered parts with the shop truck quickly grabbed the hose and scared the crap of me. I screamed NOOOOO!!!! and he stopped. I covered the can and the fire went out(deprived of oxygen). No matter how you quench safety should be a concern.

When I quenched I use 2 gallons of distilled water and with props being so small there was never an eruption. When quenching oil hardening tool steel/drill rod we used oil over water, ie: in a 5 gallon pail (steel) with water about 3/4 full and then enough 10 to 30 weight oil on top to have about 1 inch of oil over the water. When quenching steel we would swirl the object in a figure 8 pattern in the oil to balance the cooling to keep the object from warping.

Thanks, John

Lots of free flowing information now.

John - I will definetly be giving you a call. Thanks for the offer of help. I do have some further questions.

Thanks all - Doug

John Beardslee said:

When I quenched I use 2 gallons of distilled water and with props being so small there was never an eruption. When quenching oil hardening tool steel/drill rod we used oil over water, ie: in a 5 gallon pail (steel) with water about 3/4 full and then enough 10 to 30 weight oil on top to have about 1 inch of oil over the water. When quenching steel we would swirl the object in a figure 8 pattern in the oil to balance the cooling to keep the object from warping.

Thanks, John

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Cat urine...