Best way to make a prop mold?

[jaxracer]

Hey guys,

As the title states, looking for recommendations on the best method to make a prop mold. I’ve seen some ideas via Google but wanted to get a few others to try too.
Thanks!

 

[John Beardslee]

Mitch are you wanting to mold wax models to then have cast or a pitch block style mold to check to make sure a prop hasn’t gotten bent?
John

 

[jaxracer]

Mitch are you wanting to mold wax models to then have cast or a pitch block style mold to check to make sure a prop hasn’t gotten bent?
John

Hey John,

The second one. I have a couple props running now that would be devastating if they got destroyed so needed to mold them to bend them back if they ever got bent and/or make a duplicate for a backup.

Thanks!

 

[ricwally]

Marty Davis and John Ackerman had ties to a couple guys that used to make pitch blocks like you are speaking of. I inquired about them some time ago and never got a response. I have four from back then. They are very handy for coming close to duplicating props. They had proven prop blocks for various size motors. Alos, you could send them your prop in order to have a duplicate made. The adjustable collar on the shaft allowed for pitch increase or decrease as you desired.
They are made out of a metallic type epoxy or something similar. Very durable. It would be nice if someone could start offering that option again.

 

[LohringMiller]

It's easy. I built a board with a series of 3/16 shafts sticking out. I used epoxy putty under the blade of the prop(s) I wanted to duplicate. Grease the prop to prevent sticking and carefully form the edge of the putty blob to match the shape of the prop blade. You can also use the duplicator to test the accuracy of pitch and blade form of the other blades on the prop.

Lohring Miller

 

[Mike Hughes]

Ditto what Lohring says. DId that with epoxy puddy use for patching aluminum boats.

 

[Wasted wages]

One of the guys in our club, his wife was a dental assistant...she brought home some type of dental material they use to make tooth impressions for dentures etc.

he mixed up a big blob of it and smooshed the prop in as others stated above.. it hardened like a rock. He molded a 1667 for me that worked great...I could hammer and tweak a stock prop to an exact copy.

Maybe someone here could chime in about availability of this type of material.. anybody here a dentist ????

 

[John Beardslee]

Hey John,

The second one. I have a couple props running now that would be devastating if they got destroyed so needed to mold them to bend them back if they ever got bent and/or make a duplicate for a backup.

Thanks!

I use a base of 1/2” aluminum, I put a shaft of either 3/16” or 1/4” pressed in the base offset and sticking up vertical so the prop drops on vertically. I also add some screws up through the bases in the area the blade covers (I work 1 blade at a time) these screws will help keep the epoxy putty in place when you hammer on the prop. I use a wheel collar to set the prop high enough above the base to have a good thickness of putty. A picture would help but my blocks are in Michigan and I’m in FL. I’ll be in J’ville 23,24,25 of December if you want to meet. I’ll pm you my number and I can let you know where I’ll be. Mean while I will try to make a couple of sketches to help explain.
John

 

[Ray Sametz]

https://www.modelgasboats.com/magazine/tech-articles-mainmenu-608/118-prop-mold

 

[John Beardslee]

https://www.modelgasboats.com/magazine/tech-articles-mainmenu-608/118-prop-mold

Thanks Ray,
A picture is worth a 1000 words. Perfect!
John

 

[Carl Van Houten]

Hey John,

The second one. I have a couple props running now that would be devastating if they got destroyed so needed to mold them to bend them back if they ever got bent and/or make a duplicate for a backup.

Thanks!

Send it to Carl.

 

[rhomodel]

I also made amold like that: my experience though is that the steel epoxy when set can not take a lot of hammering and will break: it is better to use an anvil block and balls to shape the blade and use the cast as a guide to see if you have the same shape. Otherwise a perfect way to replicate the shape of your favourite prop.

 

[JAMEYGALLIHER]

One of the guys in our club, his wife was a dental assistant...she brought home some type of dental material they use to make tooth impressions for dentures etc.

he mixed up a big blob of it and smooshed the prop in as others stated above.. it hardened like a rock. He molded a 1667 for me that worked great...I could hammer and tweak a stock prop to an exact copy.

Maybe someone here could chime in about availability of this type of material.. anybody here a dentist ????

What you are talking about is called die-stone , some pretty tough stuff when mixed with water

 

[Rick Doane]

Here's a different approach. The aluminum shell was machined with a roughing end mill to create grooves in the sides so each mold can be slid into each half from the top of the shell and lock in place. Epoxy putty is used for the forms and a clear grease with some wax paper on the flat areas are used to keep the epoxy from sticking where it is not desired. Care to center the prop is important especially when the form is used to bend full blade pitch in or out. Up to a half inch pitch (depending on blade) can be applied to the blades when placed in a vice and twisted with a matching shaft. Always remember to check the balance of the blades when doing this as it WILL change. Diameter too. Great for getting your prop back to the original shape as possible and less hammering of the prop and hardened putty.

Regards...Rick

 

[DON MAHER]

Very cool idea Rick!
Hope your doing well.

 

[Wasted wages]

What you are talking about is called die-stone , some pretty tough stuff when mixed with water

Is this something that the general public can buy ?
I know the stuff my friend worked with was like rock when hardened... I would like to get some more of it to make some current molds.

 

[John Beardslee]

Here's a different approach. The aluminum shell was machined with a roughing end mill to create grooves in the sides so each mold can be slid into each half from the top of the shell and lock in place. Epoxy putty is used for the forms and a clear grease with some wax paper on the flat areas are used to keep the epoxy from sticking where it is not desired. Care to center the prop is important especially when the form is used to bend full blade pitch in or out. Up to a half inch pitch (depending on blade) can be applied to the blades when placed in a vice and twisted with a matching shaft. Always remember to check the balance of the blades when doing this as it WILL change. Diameter too. Great for getting your prop back to the original shape as possible and less hammering of the prop and hardened putty.

Regards...Rick

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Rick
Those are very much like Ed Kaulfus used as well as Jimmy Allen.
John

 

[Rick Doane]

Hello Don. Thank you. All is good here as I hope you and yours are doing well. Merry Christmas!

John....The first molds that I made were back in the early 1980's on a piece of pine board using polyester resin. I've still got that thing somewhere. Of course, the resin cracked when force was applied but generally got the job done. I was not aware of Mr. Kaulfus' efforts back then, but I had a great conversation with Jim several years ago about this and the point we thought was the most interesting part was the parallel thought process that occurred prior to any knowledge of each other.

Regards....Rick

 

[JAMEYGALLIHER]

Is this something that the general public can buy ?
I know the stuff my friend worked with was like rock when hardened... I would like to get some more of it to make some current molds.

I'm not sure we order from a dental supply company , the stuff we get today is hard as a rock but it is not as hard as it was 20 years ago .