How to internaly reinforce a resin casting?

[Chuckt5]

I am working on a 1/32 Albatross W.4 float that I want to cast copies of for both sides. It is roughly 6" long by 1" by 1" tapering down at both ends.

I'm wondering how I go about securing a brass rod/wire in the center of the mold before i pour in the resin to cast with? How do I do this without sacrificing external detail? Any tricks to this?

Thanks in advance, Chuck.

[ALBATROS1234]

if i get you the problem is you want to reinforce a resin float with brass rod. i cast resin, but i have never done something exactly like this. my first thought would be to pour half the resin into the mold. once the resin starts to thicken to jelly like consistency place your brass in. then asap pour in the rest of the resin. this is on the assumption that this is a one piece open top mold with the pour stub facing upwards. you can do it with a 2 piece but it would be harder. just when you make your mold mount the casting block to the underside of the float. ca glue that to a pour board. construct walls around you original(legos/wood/plastic card) and pour in the rtv.

why do you think it would need to be reinforced? i have a couple resin kits with floats and the dont seem to be reinforced with brass. the only things ive seen like this are the struts for karaya kits have copper wire inside them to strengthen them. and a friend locally made a 1/18 horton flying wing which he imbedded brass tube in the wing and fuselage so they could be removed for shipping.

if you are new to casting check out this link below. this is basically how most modellers cast resin.1 part and 2 part molds are covered.

http://aeroscale.kitmaker.net/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=469&page=1

[rhallinger]

Thanks for that link Alby!  I always enjoy learning something new about modeling techniques.

Chuck, glad to see that you are proceeding with the W-4.  I look forward to your progress.  If your float casting works well, you may have a small market here for 1/32 W.4 resin parts!  Good luck!

Regards,

Bob 

[Chuckt5]

Thanks guys for the input. I wasn't really sure if a cast object of that size would have issues with wanting to warp or not, so I thought I would ask just in case.

 I do think I'll need to reinforce internally the wings for the W.4. They will be pretty long and thin so I think they are prone to warping.

 I will try the halfpour method with them and maybe the floats. I will be doing a 2 part mold, but will only pour and reinforce one half before I close up mold to pour the rest (if that makes any sense).

My float master is coming along pretty nicely. I hope to have it finished this weekend and I'll post pics for feedback then hopefully.

Please stand by! 

[IvotB]

Chuck,

I don't know about the 2 part mold. I would prefer to pour a casting in one go, because I would be afraid that the total strength is too dependant on whether or not you took the correct time for the first part. Too short, the reinforcement would sink, too long, the 2 parts don't form a strong bond.

Why don't you experiment with the technique used in pouring reinforced concrete. There the reinforcement is held into place to the mould by using spacers. I can image that you could use spacers in a resin cast too. If you make them pointed at the outside you wouldn't see much of it in the final project or otherwise you just have some tiny holes to fill with epoxy.

I haven't done it myself, but I have seen reinforcements in resin castings with 1mm steel rods in castings about 10 inches long. I could ask the producer how he is doing this. It's another small scale producer of resin model railroad kits.

Just my thoughts.

regards,
Ivo

[Chuckt5]

If you could find out how it's done that would be great! 

 Let me know what you discover, Chuck.

[uncletony]

Apologies for raising the dead. I just stumbled across this dormant thread while looking for something else.

I have successfully cast landing gear struts reinforced with steel wire; they are tremendously strong compared to the original wet noodles that passed for struts. I have detailed the process in my build log but I am afraid it is buried there as it is rather long 

Anyway, I did not wait for the resin to set up or anything like that. Instead, I designed the mold so that the resin would pool without spilling, then simply pressed the top on and let the excess squeeze out the sides. Yes, this produces flash, but it is simple to clean up, it literally tears off.

 Nor did I employ spacers; I considered it but found in unnecessary as the minor deviations from being perfectly flat, both in mold and the steel wire effectively suspended the wire so that it is sufficiently encased in the finished part. If necessary I would have added dimples in the master to support the wire in the mold. The dimples could then be filled when finishing the part.








More pictures and commentary here

[ALBATROS1234]

bo i like the way you used the legos as keys. usually i use the legos as the outer wall and shape a block of clay to imbed the original then use the end of a fat paint brush to make 3-4 dimples in the clay for keys. i might try this way.

[Chuckt5]

Very nice Bo!

Thanks for taking the time to breath life into this dead thread AND for sharing your technique. I will give it a try when (speaking of raising the dead) I get back to working on my Albatross W.4 conversion.

Thanks again, Chuck.