screw on backs to props / resin

[propologist]

Let me see if I can word this properly for the gurus. I am working on the Superfriends communicators and a few other projects and while i had planned on making them static , i have had alot of people wondering about making them active.
my question is , if your casting in resin , How would you make a screw on back where a battery could be replaced ? I understand making a two part piece, but what about the screws being able to be unscrewed ? I am looking for pre-existing basic walkies i could take apart and use for the electronics maybe.

Here's one of the reference images . If you had say three screws on the back to hold it on , how would you " cast" the threads to screw it into....? I want to add the antenna and buttons as well . Does anyone have a good resource for various buttons and components of the like ?

 

[adamata]

I dont know about casting the threads, but depending on the resin you use, you could always hand tap them with a tap/die set like this

http://www.amazon.com/Allied-49035-41-Piece-SAE-Tool/dp/B000EMDI2Q

Just a thought

 

[Node Nine]

I would think you could incorporate a properly sized (and removable) screw into the mold so that when cast, you would be left with a threaded hole. I would worry about easily stripped threads in that case, though.

Personally I would cast in a threaded insert for durability.

Something like http://www.ezlok.com/Home/index.html

 

[fuelish]

Could you cast threaded inserts in?

 

[propologist]

man , never thought of it that way...hummmmm thanks guys , something for the drawing board

 

[clonesix]

Easiest solution: Self -tapping screws
second: Mold the threads into the part. they will work, but strip easier.
Third: Cast T-nuts into the base.

 

[Sidewinder]

I find that resin takes threads quite well so long as u dont overtighten. I dont use a tap, I drill eg. a 2.5mm hole for a 3mm machine screw and use the screw itself to create the thread in the hole.

SAS

 

[propologist]

Easiest solution: Self -tapping screws
second: Mold the threads into the part. they will work, but strip easier.
Third: Cast T-nuts into the base.

i was thinking the same with self tappers , will have to experiment when i get to that point with some dummies.

 

[defstartrooper]

I'd go the threaded insert route, never have to worry about stripping the thread that way.

 

[Mostly Fantasy]

Fuelish is right- I used to insert mold threaded inserts for urethane all the time. That way, you don't have to worry about spreading/cracking the urethane with self-tapping screws.

 

[wondersquid]

If I may offer some professional experience in this matter?
I used to do sales models for industrial design pieces. (raid arrays, computer towers, etc.) When we created the prototype we would drill and glue threaded inserts into the master, with a special machined screw post that had a ridge for registration. Then when the silicone mold was made, you would have a cavity with a depth registration point. Then we would screw a threaded insert on the special post and then insert them into the silicone mold in the cavity points. When it was cast, the threaded insert was imbedded about a 1/16" below the surface of the resin. (we used some crazy-ass expensive resin) and when the finished part was pulled, you had threaded holes for assembly and you never saw the inserts, or worried about threads stripping, or even the insert coming out.

 

[Funky]

I find that resin takes threads quite well so long as u dont overtighten. I dont use a tap, I drill eg. a 2.5mm hole for a 3mm machine screw and use the screw itself to create the thread in the hole.

SAS

That's the method I usually use. Now if the person who's screwing it in is in a hurry and heavy handed, you could very well be...well, screwed.

 

[Mostly Fantasy]

[/QUOTE]Re: screw on backs to props / resin
If I may offer some professional experience in this matter?
I used to do sales models for industrial design pieces. (raid arrays, computer towers, etc.) When we created the prototype we would drill and glue threaded inserts into the master, with a special machined screw post that had a ridge for registration. Then when the silicone mold was made, you would have a cavity with a depth registration point. Then we would screw a threaded insert on the special post and then insert them into the silicone mold in the cavity points. When it was cast, the threaded insert was imbedded about a 1/16" below the surface of the resin. (we used some crazy-ass expensive resin) and when the finished part was pulled, you had threaded holes for assembly and you never saw the inserts, or worried about threads stripping, or even the insert coming out.

(This is what I referred to by way of insert molding.)