simple Hi-Tek coating

[Jatz357]

I’ve never heard good things about IR thermometer accuracy, especially when measuring lead.
There actually is a recent thread here that touches on them -

https://castboolits.gunloads.com/sho...ad-thermometer

For now I’ll call my new Tru-Tell 200-1000F casting thermometer my most trusted thermometer and try to get it tested in the future.
If I build a PID and it matches the Tru-Tell that will be close enough for me.
But I’m a geek and prefer to have at least 1 calibrated device in house, stored safely and used only to verify the daily use gauges. An in house calibration system.

I prefer to be picky when it comes to measuring devices, when I’m not I get burned like this. Or like when I built the stand for my Lee pots, used a tape for the some pieces and a square for the other ones. Put it together and the top didn’t fit perfectly.
Checked and the stupid cheap tape I used had a severely bent hook, it read probably 1/4”-3/8” short.
Shame on me for not checking it.


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Infrared thermometers are not very accurate with molten lead, uncoated projectiles or reflective surfaces in general.

Once projectiles are coated, temperature readings with an IR thermometer are more accurate.

[dikman]

Much has been written in this forum about PIDS and many use them for casting. Even if they're not completely accurate any variation is only likely to be maybe +/- 5 degrees, not the 60-odd you've experienced. I don't recall anyone having those sorts of issues when using a PID, I use them for casting (2 pots) and in my little toaster oven for coating and never had a problem with them.

[Jatz357]

Much has been written in this forum about PIDS and many use them for casting. Even if they're not completely accurate any variation is only likely to be maybe +/- 5 degrees, not the 60-odd you've experienced. I don't recall anyone having those sorts of issues when using a PID, I use them for casting (2 pots) and in my little toaster oven for coating and never had a problem with them.

The image is of my automated caster PID's. There are two that control the lead melt pot. The temps shown are this morning before the pot was turned on. There is 2.1 degrees difference. Both PID's, connectors and K type thermocouples are identical. Thermocouples are just cheap no brand. I have not bothered with calibration and have no issues.

IR thermometer taking a reading on the outside of the melt pot (flat back colour surface) 15.4 degrees. Pointing at the solid lead in the pot I was getting 15 - 15.8 degrees. Shed thermometer read 14.8. There is a bit of variation there.

[Tazza]

You make a very good point, my pid for my pot reads about 2c low as well. I never bothered calibrating it either as i just alter my melt temperature to get the lead liquid and good fill out, when it's there, there is no reason to change it.

For an oven to cure, i do see the need to have something to confirm the temperature reaches the cure mark, or else you're wasting your time. I did this once, i had it too low, and they never cured, a second lap at the correct temperature did the job.

[HI-TEK]

You make a very good point, my pid for my pot reads about 2c low as well. I never bothered calibrating it either as i just alter my melt temperature to get the lead liquid and good fill out, when it's there, there is no reason to change it.

For an oven to cure, i do see the need to have something to confirm the temperature reaches the cure mark, or else you're wasting your time. I did this once, i had it too low, and they never cured, a second lap at the correct temperature did the job.

I may be incorrect with my assumption, but what I seem to be constantly reading is, people quoting the Oven temperatures.
No one seems to be checking what is actual coated product temperature that is being cured.
I again stress, the oven provides the heat what ever the setting is set on the oven.
The product must get to 180C and stay there for about another 2-3 minutes afterwards, (at 180C).
If oven is set or is over heating with poor thermostat control, at 250C, after the product reaches 180C and with the extra 3 minutes baking with oven producing 250C, it will very quickly reach overbake temperatures, and well above what is required, and coating colour will be damaged.

[Tazza]

My baking mishap was my own stupid fault, i'm now more careful to ensure i get my cast to curing temperature.

I have never measured projectile temperature, but with messing with wipe and smash testing, i know that my oven settings with baking times does get the cast to 180c for more than 2-3 minutes so they are cured.

Every oven will be different, i have worked what works for me and my oven, when it dies and is upgraded, i'll have to do the fiddling again unless i do as others have, installing a thermocouple in a projectile to see how long it takes to hit curing temperature and repeat it.

[dikman]

I made up a cast boolit with a temp probe inserted to see what the temps were doing in the oven and it's close enough to the PID that I don't worry about it. I already knew my oven/PID was working fine, I was just curious. I've never worried about whether a PID is accurately calibrated.

[Tazza]

I made up a cast boolit with a temp probe inserted to see what the temps were doing in the oven and it's close enough to the PID that I don't worry about it. I already knew my oven/PID was working fine, I was just curious. I've never worried about whether a PID is accurately calibrated.

I'll have some big heavy chunks of lead to coat in the next few weeks, i may have to look at doing this to dial things in for different weights. My only issue with using a probe in a projectile is, i don't have any other measuring devices that are calibrated. I do have a few spare K thermocouples but again, no calibrated meter to hook it up to. A few c here and there i'd like to think is not going to be an issue.

I do have some blue hi-tek on the way, so i may need to be a bit more careful to get the colour right. I'm excited to give it a go though!

[Ausglock]

I have fitted pilot lights to my oven. The 2 SSR's that run the 2 heating elements each now have a pilot light to show when they are energized. I had a runaway the other day due to a faulty SSR. Now I can see the SSR's cycling as the PID sends control signals.

[Petander]

I have fitted pilot lights to my oven. The 2 SSR's that run the 2 heating elements each now have a pilot light to show when they are energized. I had a runaway the other day due to a faulty SSR. Now I can see the SSR's cycling as the PID sends control signals.

Very clever.

[Jatz357]

I have fitted pilot lights to my oven. The 2 SSR's that run the 2 heating elements each now have a pilot light to show when they are energized. I had a runaway the other day due to a faulty SSR. Now I can see the SSR's cycling as the PID sends control signals.

This the infrared oven PID control. I used illuminated switches so it was easier to see if the PID was on or not. Green is circuit on, Red is PID active.

[Tazza]

"idiot" lights are a great invention, you can see at a glance if things are on or not.

[Jatz357]

"idiot" lights are a great invention, you can see at a glance if things are on or not.

And if I was smart, I'd use the PID alarm function as an additional safety just in case the temperature was to exceed a set maximum threshold.

[HI-TEK]

And if I was smart, I'd use the PID alarm function as an additional safety just in case the temperature was to exceed a set maximum threshold.

Jatz & Tazza

With the way you all seem to be heading, it may end up a smart machine, self thinking, self fixing, and non reliant on human errors, producing product automatically....LOL

[Tazza]

Using the alarm function isn't a bad idea, even if you used that on an SSR to cut power to the heating elements if it hit a set point that indicated that an SSR blew and us now not turning off.

Joe, we can only hope we can get to a point they aren't too smart and work out they don't need their creators anymore and to just do our menial tasks for us "plays terminator theme song in the background"

[Ausglock]

Was talking to a mate in Victoria who makes gas IR heaters for potato chip and coffee bean roasters.
He can do a Gas IR heater with a rubber conveyor. He is sending photos of the units.

[HI-TEK]

Was talking to a mate in Victoria who makes gas IR heaters for potato chip and coffee bean roasters.
He can do a Gas IR heater with a rubber conveyor. He is sending photos of the units.

It would be great if we can get a few kilo samples of roasted Coffee Beans as well to have decide if oven works OK or not... Just thinking...
I wonder what temperatures would the system take, especially the Rubber conveyor. If it is a Silicone rubber type it may be able to withstand 180C plus, but for how long is a question.
I used IR oven in my younger days to dry from moisture, from sensitive photographic chemical crystals. They were in stainless steel trays, that required occasional mixing and turning over with a stainless spatula. It was a gentle way of drying with low wattage IR globes similar to what is used for bathrooms to keep warm.

[Jatz357]

Was talking to a mate in Victoria who makes gas IR heaters for potato chip and coffee bean roasters.
He can do a Gas IR heater with a rubber conveyor. He is sending photos of the units.

I researched these a while ago. Know as Gas Catalytic IR. At the time I didn't find a lot of information, wanted to know if they were short or long wave IR. I thought they might have been more like halogen IR and they would heat the exterior faster.

Some companies say there is a 50% energy saving compared to a conventional oven and 3:1 time saving. For every 3 minutes it took to heat or cure something the gas IR takes 1 minute.

[Tazza]

My only concern with a gas IR curing oven would be a possible ignition source of the gasses from when it cures, but i assume Joe will advise that the gasses are not flammable?

IR heating is a far better way of transferring heat, you are heating the objects directally, and not the air that in turn heats the object.

[HI-TEK]

My only concern with a gas IR curing oven would be a possible ignition source of the gasses from when it cures, but i assume Joe will advise that the gasses are not flammable?

IR heating is a far better way of transferring heat, you are heating the objects directly, and not the air that in turn heats the object.

Tazza
I am aware that some manufacturers are using LPG or natural gas heating to bake coated projectiles.
In all the years, I have never been advised about any ovens with fumes catching alight .

I have many times, repeated, that air is a very poor conductor of heat. That is why ovens need a fan forced circulation to get hot air to make contact with what is baking baked as many times during bake cycle, to try and transfer heat from air into the product.
What has now been proven is, that IR heating does not heat the air, but heat directly goes into the metal, and as metal heats up, the heat radiates outwards and cures the resin.
The IR system mostly eliminates the coatings being burned, with trying to force heat through the insulating property of the coating, as the heat is actually generated inside alloy radiating outwards.