Reading temperatures

[dallen]

900 Celsius I don't know the conversion off the top of my head but I don't think it will go high enough to do bronze which most of the alloys like to be poured around 2100F.

A lot of people also mistake surface finish problems to the metal being too hot when if may be being caused by the molding sand.

one problem with the laser type temp probes is that unless you can get a good hit on the surface of he molten metal out of the furnace your likely going to be reading the exhaust temp of the furnace which can be a lot hotter then the melt. dip type probes for metals like aluminum and brass and bronze can be made fairly easy if a person can find the right material.

[Terry S]

There are two systems traditionally used in the industrial world.

1) "Immersion" type probe with a high temp thermocouple on the probe - usually type K or type S. You need a thermocouple readout with the proper calibration setting to use the probe. This system works well on small furnaces (such as home shop) where the operator can safely approach the furnace opening. The probes are considered disposable. When the probe eventually fails you replace it with a new one. You want a probe that is 2-3 feet long to keep your hand back from the heat. In today's electronics world, people like Fluke make relatively inexpensive readout devices.

2) "Optical" type telescopes. Intended for use with large furnaces where the operator must stand back 20 -30 feet to take safely the reading. (But can also be used on small, shop furnaces). These are non-contact devices that use a small telescope. You look through the telescope at the hot metal. You are also looking past the filament of a small light bulb in the field of view. You adjust a knob which regulates the current flow through the light bulb until the filament "disappears." At this point the filament temp = metal temp. The knob is calibrated in temperature. These instruments were designed for the steel industry and were ruggedly built. You can find used versions on Ebay for not much money. "Pryo" is one brand. "Leeds and Northrup" is another.

Terry S.

[stevec]

900° C equals 1652° F from the "Convert" program, great to have one your toolbar.

[RobWilson]

Not to go to

(08-11-2014, 03:46 PM)stevec Wrote: 900° C equals 1652° F from the "Convert" program, great to have one your toolbar.

I agree , this is the one I use all the time http://joshmadison.com/convert-for-windows/


Rob

[TomG]

Here is an inexpensive option that will read up to 2000ºF with a type K thermocouple.

TES-1310 Digital Thermometer

It's a lot less expensive than the Fluke, so when it gets melted, you won't feel so bad.

The same place also carries PID's if you want to control the temp. I used them on my anodizing set-up and they work very well.

[dallen]

temps not high enough to do bronze with.

[Mayhem]

I wonder what the custom probes to measure that temp are worth?

[dallen]

It's normally not the K type thermalcouple probe that won't reach the temp, but the readout that's hooked to it. and when you start talking about Platinum Probes for temps about 2300 degrees F your talking serious cash for one.

I ruined a K type probe that Mifco sells for their hand probe by getting it too hot on a cast iron melt think I melted the wires inside the graphite cover, I know the ceramic insulators on the wires melted to the wires. If I can find it I'l take a photo of it and post it n here.
Its around here somewhere.
DA

.

[vtsteam]

You need a type R thermocouple for iron. But I have never used one for aluminum or iron. I've just poured when it acted right on the stirrer (1/4" steel rod) . For aluminum, it should come out clean, not globbed up. For iron it should come out without slag attached, and like dallen says, maybe getting shorter, and pointed!

Oddly enough I did feel the need to use a temp sensor when pouring diecast metal lately doing thin section lost foam. It's a lot lower temp pour than even aluminum. The reason -- I wanted hot metal to melt out the thin sections, but not fuming zinc, so settled on 450C for pouring. The only way to tell that closely was use a thermocouple. I used a Harbor Freight multimeter that comes with a K-type thermocouple. I put the thermocouple in a couple feet of 1/4" stainless tubing and crimped the end. bent it to a curve for easy dipping. It worked well.

[Artie]

Soooooooo.... taking on board the comments, I looked further and pretty much discounted the use of the laser style gun.

Type K thermocouple is the go, the unit I've bought has a range of -100° C to 1250° C will fit my fluke.... in fact I bought 2 which I'll fit into a stainless tube to dip.....

Cost? well that's the bit I like, not a lot....$2.81 AUD, I think that's 1 Pound 57. So I got 2, if they are not real good, then Ive not lost a lot.... bloody amazing....