Metal Casting Zone

Is there a point where if pewter gets too hot or has been remelted many times over, that it is no good for casting?

I wouldn't think so but...!?!?!?!

Hi Spad 13

Quite right
It is possible to melt the pewter to much and to many times.

First don't heat the pewter too hot ,Pewter can attact a iron melt pot if rasised to too higher temp,50oc over the melt point is really all that is needed but then depending on what you are casting depends on the temp. I spin cast pewter and have to vary my temp 30oC up or down depending on the model item I am spin casting. and am of the opinion that the temp of the metal is a very critical area of spin casting. As the rubber moulds I use heat up I knock down the temp a little at a time . Having a thermocoupler to show temp readings is essential. And a probe to check this, JUST TO KEEP BOTH IN CHECK. often they are different.
If you keep remelting your metal and no new alloy is added as well over time the castings do start to show a poor surface.

Hi John,

Thanks for the advice, I fear some of my pewter may have been melted too many times as I have been practicing.

If you see the pictures on my other post, is that what the bad surface looks like?

Thanks,

Bruce

PS Your avatar looks like a RGS model T railcar. What scale do you model in?

The image below will show what over heating pewter for a long time and re-pouring it about a dozen times will do minus a nice 2 ounce hummingbird cast. That was one bar of pewter, supposedly tin, antimony and silver, but I doubt it.

Hello JohnCast, Stephen here,

I am a bit confused by the following statement.

"Having a thermocoupler to show temp readings is essential. And a probe to check this, JUST TO KEEP BOTH IN CHECK. often they are different."

Isn't the thermocouple connected to the probe, or do you have two probes, one in the molten metal and one where? I realize you are spin casting but I might get into that too. So if you will pardon the pun would you please tell me where to put it?

I am doing gravity pours from a 10 pound lee pot. I realized a real need to get a handle on temps. And was debating buy one of the following.

A Non-Contact Infrared Thermometer and or a $25 Atkins Thermocoupler model. Any comments on the use and viability of these two approaches?

www.amazon.com/IRT0421-Non-Contact-Infrared-Thermometer-Targeting/dp/B0017L9Q9C/ref=sr_1_5?ie=UTF8&s=hi&qid=1263776191&sr=1-5
www.ebay.com Search item 380198868914 Or amybe the following link will work.


NOT: Thanks to Jammer for the lead on the inexpensive Atkins listing!

Stephen

Hi Stephen

Sorry for any comfusion ,maybe I worded this wrong. in last post
ok My iron melt pot of 10kg of metal has a thermocoupler controller fitted.The probe section which is like a thick woven wire 3 foot long slides down into a stainless steel tube about 9 inches long that is positioned down the side of the pot and has the lower 6 inch of it sitting in the molten metal. The stainless tube down the side of the pot is selled at the lower end the thermo wire gets a temp reading from here, like a drinking straw would sit in a glass of soft drink. With the lower end of the tube sealed no molten metal comes into contact with the probe wire .I dial up the temp I require on the control box and this sets the temp fo casting .Though this seams to be ok some area for incorrect readings do arise..So a probe is placed in the centre of the molten metal for a few miniutes through the day and the readings compared. The hand probe was'nt cheap but I think it is a must have, if you do a lot of casting. Comparing the two readings the controller box is ajusted to better equal the temp of the probe. Probe removed and casting continues.
Its not unusuall to have the controller dial 10oc less to compensate for in accurate temp readings. This happened before CHristmas on a casting run ,,casting were not giving a good surface and the temp was out by 10 degrees JOHNCAST

Hi Spad 13

The railcar in my avatar (AVATAR is this what you call this )is off this site not my models I just placed this here becauce it reflected models. Not mine.

Look into my profile page and look at some of my brass casting shots and spin casting shots

To see a complete range of the 1/87 castings for model railways I do. go to the web site of antonstrains.com.au and click on the uneek models icon. these are all white metal castings that I have painted and modeled for my displays at my shows.

Thanks a heap John, that clears it up. Also interesting that 10 degrees can make a noticeable difference. I'll keep the idea of two dissimilar thermometers for the same pot in mind as an option. Especially if I do not get good results.

This link better got me to your castings and paint ups. Very well detailed. They trigger some memories of my younger days.

www.antonstrains.com.au/store/index.php?cPath=21

Stephen

The basic pewter doesn't go "bad", but it gets contaminated with oxidized metal that is put back in and repoured.
Always use a skimmer to clean the dross off the surface of the melt, during preparing to pour.
Zinc does the same thing, but if you clean off the dross, you can use it until it is gone.