First mold making - 3d printed buck

[thenated0g]

Some sanding and filling.
Epoxy and sanding filler. Super easy to sand. Hardens shiny so you can see low spots.

 

[Doc James Hammond]

Some sanding and filling.
Epoxy and sanding filler. Super easy to sand. Hardens shiny so you can see low spots.

View attachment 11144

Looking good, Nate!

Remember NOT to use cellulose based paints for the finish, or your carefully sanded plug will inevitably stick inside the mould and have to be surgically removed.

Looking forward to seeing the finished moulds.

Cheers,

Doc.

 

[thenated0g]

@Doc James Hammond do you know of some brands that are safe for mold use without me going to look at our RC groups?

 

[thenated0g]

Sanding!
Extra filler goes on the Jart fuse

 

[Doc James Hammond]

@Doc James Hammond do you know of some brands that are safe for mold use without me going to look at our RC groups?

Hi Nate - Any epoxy paint is OK, most acrylic car paints are OK.

Worst are rattle can paints, or self-mixed cellulose.

Cheers,

Doc.

 

[thenated0g]

I did find some of this on the shelf

 

[Wayne]

Careful - In the spray can world they are not shy about calling things epoxy that are not epoxy. Same with pretty much all paints at the discount places. Ran into this when looking to paint a garage floor.

 

[thenated0g]

right now im using some rust oleum 2x grey primer. Its an acrylic enamel. Just using it to build up some fill on it after sanding.

 

[Wayne]

What will you be using for a mold release? If PVA, I think you could use just about anything. But when you start getting more exotic, you will need to pay very close attention to anything you put on your plug/molds to avoid very bad results, yes, even at the primer stage. Sadly I have seen many chemical reactions over the years, both with my own, and with others that are sharing their builds.

One of the issues I have seen over and over with spray paints is that they continue to cure over a many month period. How do you know when it is done? You really don't, but one sign is if your shop still smells like spray paint when you have been out of the room for an extended time. When I painted cars with rattle cans, I would let them cure in the sun for a couple of months. Then I could come back and polish that spray paint to a point it looked really good. If you didn't give it those months to harden and cure it simply could not take the polish abuse and looked like crud.

There are far better spray paints out on the market, but you will pay dearly for them. You will not find them at any of the discount chains. For my automotive and around the shop uses (and my plane) I like the SEM brand a lot. Good stuff. The cans may be spendy, but they do seem to pack a lot more paint into the can, and it dries faster and cures harder. All good stuff. (Not saying it is right at all for your application.. I have no idea!)

Loving this project, looking forward to each update.

 

[Doc James Hammond]

I did find some of this on the shelf
View attachment 11165

I have good reports of that stuff from the UK.

Doc.

 

[thenated0g]

@Wayne mold wax and pva

 

[thenated0g]

I will get the positive part complete and let it sit for a couple weeks just in case.

 

[Doc James Hammond]

I will get the positive part complete and let it sit for a couple weeks just in case.

Good idea Nate.

I don't know what mould wax or PVA you are using.

Bit of advice - if you know this then please disregard.

- PVA can be thinned down to 10% and still work very well and it sprays or wipes with a fine sponge much better if thinned.
- For wax I normally try to find the"TR" or "Partall" types as they seem to work and buff up a bit better than the others.

If you do get TR wax, then please don't be tempted to use the high temp stuff (unless you have to) because its really difficult to buff up once applied.

Couple of cents worth.

Doc.

 

[thenated0g]

Here is what I have. What I use on mylar in vacuum bagging.

 

[Doc James Hammond]

Here is what I have. What I use on mylar in vacuum bagging.
View attachment 11169

That will do it.

Its a good idea to apply the wax several times, waiting a half hour or so between each application in order to build up a nice wax pellicle on the plug.

Doc.

 

[thenated0g]

 

[thenated0g]

Not anything new to show here just been slowly sanding and filling. I do have the final coat of paint on just waiting for it to dry enough to wet sand it.

 

[thenated0g]

Minor set back as i had some bad interactions between paint layers on the bottom. Bunch of cracking and pin holes in one spot. Not a big deal but just more sanding filling. Was kind of odd as it was just a second coat of the same 2x grey primer.

 

[Doc James Hammond]

Minor set back as i had some bad interactions between paint layers on the bottom. Bunch of cracking and pin holes in one spot. Not a big deal but just more sanding filling. Was kind of odd as it was just a second coat of the same 2x grey primer.

Hi Nate - do you know, in all my moulding/plug making exprience I have never, ever, used primer. Not once in 55 years.

I am not sure why primer is even used on modelling projects.

Can anyone enlighten me?

Cheers,

Doc.

 

[Wayne]

Because I am lazy.. LOL And the pray can companies tell us we must prime first. It is on the label, they wouldn't lie!