Reading temperatures

[Bigbadbugga]

A question for those guys who run a furnace and do a little casting.

How do you measure the temperature of the furnace and molten metals?

I've seen lots of YouTube videos and read lots about the temps needed to cast, but can't find much info about how those temps are measured.

Or are they just educated guesses based on known melting points and flame hues etc?

[dallen]

well you can take a guess at it or buy a probe to measure the temp wth, or you can make one out of a multimeter and a thermalcouple.

some one with lots of furnace time with the metal that they are melting know pretty much how long it takes to reach a certain temp with say aluminum

[doubleboost]

After a while you get to know the colour
We always tend to run on the hot side
John

[dallen]

this is what my furnace looks like running at about 2900 degrees F

[Bigbadbugga]

Thanks guys, it's as I thought.

Edumacated guesstimation :)

I'm researching building a waste oil furnace, initially for ally but might do some iron later.

Might even do some YouTube videos of the build if I can overcome the stage fright.

[dallen]

Aluminum is easy, cast iron is like my EX "a real bitch to handle"

A little wisdom, build like your going to melt iron, but take the time to learn on aluminum first that way you only have to build once

DA

[PixMan]

Do you think an infrared thermometer would be able read temps that high? I have one for general shop use, but since I don't have a furnace nor welder I never have anything above a typical kitchen oven to measure.

[dallen]

some have tried too use the infrared jobs but most are not set up to read much more then 500 degrees. I have a fluke digital probe that uses K type probes but they are only good up to around 2300.

I gauge the temp of cast iron by stirring the pot with a piece of 3/8" rebar if the end melts off in the time it takes to stir the pot its hot enough to pour.

I know a couple of guys that have bought Pyrometer off of evil bay but haven't heard anything about if they actually were able to get them to work.

DA

[Artie]

I'm looking at an infrared that is 'supposed' to read 900° C, I'm a little skeptical about this but it isn't much money so I'm going to take a shot on it.... I also find that I tend to pour overly hot and this isn't a good thing for surface finishes in a lot of cases.

Ergo I was watching this thread with interest, Id rather just point and read if at all possible.

[Bigbadbugga]

(08-10-2014, 07:20 PM)dallen Wrote: Aluminum is easy, cast iron is like my EX "a real bitch to handle"

A little wisdom, build like your going to melt iron, but take the time to learn on aluminum first that way you only have to build once

DA

This is my plan, I'm looking to use refractory materials capable of the cast iron temperatures.

I like your tempreature test with the rebar, would the same work with a 5mm rod of ally?

I tend to work in that way anyway, that is over speccing everything so it can handle several times the stress it needs to. I'll stardom collecting materials soon and hopefully start building in a few weeks. Got my holidays at the end of this month so nothing will happen until I get back.