Bend cast metal parts

[bogeygolpher]

Does anyone have any suggestions on how to bend cast metal parts?

 

Whenever I have tried in the past to either bend them or straighten them I managed to break them and then had to make substitutes, usually out of wood because I am much more comfortable working with wood than metal.

 

I hope I am using the correct terminology when I say cast metal.  I am referring to the white metal parts supplied in most kits that usually have a little bit of flashing on them and are quite brittle.

 

Thanks in advance.

[WackoWolf]

I also would like to know if anyone has a way of doing this since from what I have read about this suject in the past all say that it cannot be done. Can anyone shead some light on this subject

[Spaceman Spiff]

I have thought about this, too. Would heating it work? I know that heating (annealing) PE parts makes them easier to bend, but I don't know if this would apply to white metal parts.

[JPZ66]

It really all depends on what the metal is.... I used to cast pewter parts, and it was maleable enough in smaller diameters that it could in fact be bent or straightened in many cases....stanchions, gun barrels, etc. As the thickness becomes greater, it becomes much more difficult. Heat, is not likely to help the cast metal part, and may possibly melt it ! Some casting metals have a low melt temp.

 

It may also be possible, depending on just what the part is, to hammer it using a jewelers hammer and anvil. Sometimes you may want to use a piece of hardwood against the part, and strike that with the hammer. If you think the part may be a loss, you may as well try some experiments !

 

-Joe

 

PS- often times, if the metal was cast at too high a temperature, it will become too brittle and there really isn't much you can do.

Edited January 31, 2014 by JPZ66

[NMBROOK]

I have not tried with white metal,but annealing works with brass castings.If it is a big bend then I anneal and bend so far and then anneal again.This overcomes the work hardening caused by bending.

Kind Regards Nigel

[Mahuna]

I've used cast metal bird feet in my bird carvings, and they can be bent by warming them in boiling water, then CAREFULLY bending them to the position wanted.  You might try this on your cast parts.

 

Frank

[realworkingsailor]

Heating white metal parts can be risky, as you do risk melting them. In the case of cast decorations, look into making a resin copy. Urethane resin plastic can be easily bent after a quick dip in boiling water, and will cool and harden again, without risk of melting the part.

 

Andy

[NMBROOK]

One way to heat to avoid melting them would be to put in a domestic oven.The lowest melting point for this type of metal is around 230 deg c.If the oven is set below this,no matter how long the casting is in the there it will never exceed the ovens temperature.I agree with Andy though,resin copies could be the way to go.You can actually remove these from the mould when still 'green' ,they are hard enough to maintain their detail,but still soft enough to be shaped to a contour.

 

Kind Regards Nigel

[bogeygolpher]

Isn't this typical?  You ask about something and it almost always leads to something else.

 

Thank you for your answers to my question.  I tried the heating thing and it did not work.  I do not think I got it hot enough in the oven or in the hot water because it still snapped. To be honest, I'm not sure exactly what these castings are made of, and if it contains any lead I really do not want to raise the temperature to the melting point.  So I may have wimped out in getting enough heat on the castings to be able to bend them.   What I still do not understand is how the castings (railing posts) got bent in the first place without breaking.  I guess it really doesn't matter because the fact is they are bent.

 

That said, the suggestion to make resin copies intrigues me and seems to be a great solution.  I found the resin materials are available from the hobby store or on-line.  What do you use to make the mold, and are there any other tricks one should know if attempting this?  Is there a how to on this process somewhere?

 

Thanks again.

[reklein]

White metal castings can be bent,but you must do it gradually and support the whole piece with your fingers as you bend the piece. You don't usually get a second chance as the metal hardens as you bend it. So trial fit the piece as you bend it to fit whatever you're trying for so that you don't have to rebend. I have done this with parts from the Bluejacket Constitution and had success. BILL

[JPZ66]

Re: how to mold for a resin casting....

 

First, a couple of questions....how big are the parts ? ( perhaps you can post photos of the item in question?) Next, if it is railing, would you be able to perhaps scratchbuild the item in brass ? I'm not sure that railing or any exposed delicate part is best suited for resin....

 

That being said, there are a few ways to go about reproducing a part in resin. For something small, it is quite possible to use an 'off the shelf' tube of 1 part RTV silicone, such as silicone caulking to create a very simple 1 part molld - if the part is small and not overly 3 dimensional. It can escalate quickly from here though !

 

If the part is larger or more complex, you may need a proper mold making silicone, such as Silicones Inc GI-650. A two-part silicone, and while possible to make decent molds without vacuum degassing, it is always best to degas the silicone after mixing, before pouring. I did see in the articles section here, a fairly simple tutorial about mold making.... At any rate, getting into something more detailed about setting up quality molds and casting processes is something beyond a simple reply here, and if you should desire a detailed overview of this, feel free to contact me via message. Some years ago, I had a shop and was producing kits and parts for a number of smaller companies. In addition to resin casting, I also did pewter production castings..... I hope to one day return to that at least on a part time basis. I might even consider a mold making service that would provide the end user with a quality working mold they can then use to make their own castings from.....

 

I do think that a number of folks might benefit from a more detailed and comprehensive article about the process and at some point in the future I will write something up and submit it for review. Unfortunately all of my equipment and such is put away and will likely not be useable for many months yet, as I am preparing to move.

 

-Joe

[JPZ66]

Oh...I should like to add that there are some low temp melting metals available (can actually melt on a stove top) for use in silicone molds, and there are also high temp resistant rtv silicones available ( I have often used these to protoytpe with ) for casting metal.

 

 

-Joe

[bob66home]

But the subject still seems unresolved. I am facing it now  with the railings on Disar model tug Vanguard ehere a very slight curvaaature is required to meet  the deck. Any experience out there?

[Snug Harbor Johnny]

  'Looks like you don't need much of a bend to meet the curve of the deck.  Suppliers are VERY unlikely to use lead-containing alloy these days (which easily bend), for one thing, it is likely illegal.  That leaves zinc the likely material, which can be brittle depending on what "else" there is in the alloy.

 

  A form could be made with just a little (and I mean little) more curve than what you need, and there has to be portions cut or filed out where those vertical thicker areas are shown in the photo.  Only the thin area of the cast bulwark will contact the wood of the form.  You can heat the cast metal in boiling water, since the only alloy I know that melts in boiling water is 'Woods alloy' (used for sprinkler heads and 'trick' spoons).

 

  The warmed metal can then be gently pressed against the shallow curve of the form with a gloved finger or palm. 

[Gregory]

In addition to boiling water you might add somethin like this to your tool chest.

 

Mini Heat Gun

 

 

Use with care.  It gets very hot.  will melt some plastics and will char wood.

[tlevine]

How brittle is the metal?  Have you tried placing the pieces on a curved piece of wood (or even the side of a pot) and gently hammering in a curve with a rubber hammer?  

[Bill Hudson]

On 4/5/2023 at 12:52 PM, bob66home said:

But the subject still seems unresolved. I am facing it now  with the railings on Disar model tug Vanguard ehere a very slight curvaaature is required to meet  the deck. Any experience out there?

Lead is no longer legal. When I was casting metal O scale kits the metal at that time did contain lead. When I saw the writing on the wall I changed to Pewter.  It is a little stiffer but still bendable.  I would suggest using support while bending it like bending over a round object. If it is zinc, as some one suggested, it can still be bent this little bit.  I doubt it is zinc. That is a whole different casting method and more expensive than Pewter.

 

[thibaultron]

Along this line, are the old Yellow Box Model Expo/Shipways parts cast in lead or something else. I have a couple of these kits, and would like to know.

[Bill Hudson]

If it is or contains lead, after time it will darken. Pewter will also darken over time but will still be some what silver-gray in color.

 

[Nirvana]

On 4/5/2023 at 2:49 PM, Gregory said:

In addition to boiling water you might add somethin like this to your tool chest.

 

Mini Heat Gun

 

Use with care.  It gets very hot.  will melt some plastics and will char wood.

 

I have a similar unit putting out 1500 watts. And yes it will melt plastic, char wood if not being careful. Make metal extremely hot to touch afterwards after heating, learned by lesson!