itchyTF
Gold $$ Contributor
Induction brass annealer redux
- Thread starter Gina1
- Start date
melting point of brass varies from 1,650 to 1,720 °F depending on the ratio of brass to copper
I didn't realize this was a touchy subject until I was a couple more hours into reading additional threads/sites where this has been brought about before. [1] [2] [3]
Those annealing with a flame and going for a glow (even the slightest in a dark room) are certainly going beyond 750, likely closer to the 950-1000F range. As noted in prior discussions AMP data certainly shows going beyond 750, for a very short time duration.
I'm in the process of building the GinaErick (thanks to all here for the input and wealth of information in this thread) and am trying to determine the end goals/measurements. I plan on using 750 Tempilaq to see how far down the case is warming up (ideally barely below shoulder) while using the 1000 at the neck/shoulder. Ideally, I hope to BARELY achieve the 1000 without pushing heat much below the shoulder (using .1 second and power adjustments as necessary). Lastly as a user described on the Hide, I intend to 'feel' the amount of spring back with a couple different pin gauge sizes inserted into the neck after sizing (for varying annealing duration/temperature). While this is not a Vickers hardness test or other lab test, I hope to feel the difference.
Worst case I ruin some brass and I'm still into this endeavor for way less than an AMP.
Those annealing with a flame and going for a glow (even the slightest in a dark room) are certainly going beyond 750, likely closer to the 950-1000F range. As noted in prior discussions AMP data certainly shows going beyond 750, for a very short time duration.
I'm in the process of building the GinaErick (thanks to all here for the input and wealth of information in this thread) and am trying to determine the end goals/measurements. I plan on using 750 Tempilaq to see how far down the case is warming up (ideally barely below shoulder) while using the 1000 at the neck/shoulder. Ideally, I hope to BARELY achieve the 1000 without pushing heat much below the shoulder (using .1 second and power adjustments as necessary). Lastly as a user described on the Hide, I intend to 'feel' the amount of spring back with a couple different pin gauge sizes inserted into the neck after sizing (for varying annealing duration/temperature). While this is not a Vickers hardness test or other lab test, I hope to feel the difference.
Worst case I ruin some brass and I'm still into this endeavor for way less than an AMP.
This is what I am doing as well. I'm setting my annealing time to get 1000deg on the entire neck and watching how far the 750deg runs down the body. What I'm seeing is that when the neck reaches 1000deg the 750deg is about 1/8" or slightly more past the shoulder. When I watch the "glow" with the lights out it is clear that the end of the neck gets the hottest if only for a split second. How hot I don't know as I don't have other temps of tempilaq. With normal lighting I can't see any glow. But it seems to resize fine, not being too soft. I haven't decided to go farther with the pins, etc. The case position inside the coil is another factor here to pay attention to. Left case is before annealing.
Where do you find to be a good starting point, and is there a general rule as to what moving it up or down causes? Such as lifting it heats the body more or is that not really the case?
All my research indicates that you should not have any red glow at all. Generally, the advise is to use a sacrificial case of the same brand and calibre and annealit, as you have, in the complete dark until you get that slight red glow that you mention for a split second. Then crank the timer back 0.2s and you theoretically have your ideal temp. Tempilaq 750 seems to support this. It is great to try to get the shoulder annealed too, but not if it is going to degrade the neck of the case by over heating it. A solid red glow is, by all advice, far too much heat.
Advice to me from several very experienced annealers is to use Tempilaq 750 on the neck, and when the neck is done that is it. If the shoulder is not 750 that is fine as it will be getting close, and the annealing effect starts at somewhere around 450, but 750 is the ideal and is also the max. Beyond 750 is said to excessively soften the neck of the case and there is no recovery from over annealing brass.
It is a fine balance between over cooking the neck and under cooking the shoulder. My personal preference, and I encourage all to work things out for themselves, is to concentrate solely on the neck, and then the shoulder gets what it gets. Last box of Lapua 6.5 Creedmoor were reloaded 24 times without losing a case to splitting and maintaining good neck tension throughout. I only replaced them then because I got a new barrel.
Anyway, we all have our own ideas and our own sources and advisors, so if it works for you, whatever you are doing, keep doing it. My thought is that the ultimate test is case life. If you are not splitting necks or shoulders then you are OK. Works for me.
Keep doing whatever works for you.
Using a ferrite concentrating coil I've found it easy to burn the cases like a candle, and while case placement in coil and adjusting voltage down are ways to get the right amount of heat accumulation in the neck in relation to conduction down below the shoulders, in my arduino controlled build I've implemented interval/pulse heating with variable number of intervals, variable interval length and also variable delays between pulses trying to "ride the temperature gradient" which enables me to get an "even" anneal over any length of the case I find appropriate.
Would you mind to share some interval/pulse heating experience/ example? I have similar Arduino controlled builds using ferite concentrating coils.
Any guidance or experience on ferrite cores would be greatly appreciated here too!
Cooling methods
Coil turns
Case feed
Pulsing
Something I have wondered about is the placement of the turns on a C style core do they really need to be close to the gap? ( 2 1/2 turns either side ) or could they be further back on the far side of the gap and be 5 continuous turns ?
Cooling methods
Coil turns
Case feed
Pulsing
Something I have wondered about is the placement of the turns on a C style core do they really need to be close to the gap? ( 2 1/2 turns either side ) or could they be further back on the far side of the gap and be 5 continuous turns ?
Both cases are annealed with pulses (Both are good imo - tempilaq 650F melts at the same place on both, and the same goes for 400F which does not melt below the lower part of the case). Only difference is that the top one received one extra pulse (6 vs 5 for the lower). Both cases were set to anneal for a total time of 5.2 seconds, distributed in pulses which were increased in length by 30% each time, and with pulse delays increasing 10% per time. The first delay was 100ms. The lower one received longer pulses, and more heat accumulation in the neck than top one. Had I not used pulses, the top part of the neck would have started to melt (will not show that using my precious 6.5x47 cases) - the neck would start to glow after around 4 seconds and not much heat would be conducted below the shoulders - instead resulting in a very silvery neck, with a blue "rainbow" just below the shoulder.
The litz wire plays an enormous role in the "cooling" of the coil. Find some with around 2500 or more individually isolated 0.04mm strands. (Yes, tinning the ends is a PITA) Then you'll be able to run hundreds of cases in one go at up to 50% duty cycle and the coil (the wire will cool of quickly between the anneal cycles) will be somewhere around luke warm and 60C.
I use 5 turns, having looked at the Fluxeon coil for the Giraud (I think it was also discussed earlier in this thread). I have experienced, with the ferrite cores I have tested/used, that placement of the turns has dramatic effect - the closer to the gap, the better. It could be different using ferrites of other material and form (permeability/saturation plays a part I guess) -
I use a servo, moving a feeder arm with a hole, which takes inserts for cases of various diametres.
Using a 50mm gapped "toroid" ferrite, with an annealing area of 20mmx10mm, and a gap accepting various cases of different diametres, gives you limited room for adjusting the anneal with placement in the coil. You could adjust voltage of course, use current limiting - but since using an arduino I thought why not anneal in intervals/pulses/bursts.
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Thanks for the reply's Standardelg all very useful info. For my 800 strand litz ( highest count I could find at the time ) I tinned the ends by stripping back the cotton and clear wrap to a point where I had heat shrink tubing. Then I heated a pool of solder / lead I used to use for bullet casting in a ladle and plunged the end in.
For a cleaner finish to the ends I slid them into fired .22 shell casings and crimped the whole lot together.
With some gentle reheating with a blow torch I then ran solder down into the shell case to achieve a good bond.
It is still all in a test jig form for now while I come up with a suitable design / method to present cases.
I am thinking of using a stepper to drive a 4 holed disk (like a lee turret press tool head) horizontally through the coil gap, cases will drop out once past the gap and new cases added as the disk comes around.
I am also thinking of a sensor to detect the case and then start a delay period prior to induction turning on.
The pulsing is a great idea and not something I had thought about, although I have run cases through repetitive short ( 2 second ) cycles and noted the second and third cycle always gave an accumulative effect to the case....... just never put the dots together, great work!
For a cleaner finish to the ends I slid them into fired .22 shell casings and crimped the whole lot together.
With some gentle reheating with a blow torch I then ran solder down into the shell case to achieve a good bond.
It is still all in a test jig form for now while I come up with a suitable design / method to present cases.
I am thinking of using a stepper to drive a 4 holed disk (like a lee turret press tool head) horizontally through the coil gap, cases will drop out once past the gap and new cases added as the disk comes around.
I am also thinking of a sensor to detect the case and then start a delay period prior to induction turning on.
The pulsing is a great idea and not something I had thought about, although I have run cases through repetitive short ( 2 second ) cycles and noted the second and third cycle always gave an accumulative effect to the case....... just never put the dots together, great work!
Thank you too @kiwijohn.
I cut a spent 308 case in two (primer still in), filled the lower half with solder, held it in the annealer a few times 10 seconds with some heavy pliers (heating them up as well in the process, with the benefit of working as a heat reservoir), and dipped the ends of the wire for around 30 seconds until the isolating varnish had melted and the strands had been saturated with solder and looked nicely tinned (quickly wiping off excess solder and the surfaced varnish gunk) - best done outside or in a well ventilated area - the fumes are bad. Regarding cooling, I forgot to mention I use a 100cfm fan to cool the ZVS board. I used a disc also in my first iterations, and settled for a triangle (also moving horizontally) with a single hole (accepts POM inserts with holes matching case caliber/diameter - controlled feed and ensuring centering of the case - in the ferrite/coil gap) and a servo (which always knows where it is). I have placed a vibration sensor under the floor/platform under the feeder arm, which detects when a case is dropped into the hole and "knocks" on the floor. Adjusting vertical placement in coil is simply a matter of adding riser plates on the "floor".
Thanks to the info throughout this thread and and some helpful folks here I've completed mine. No real changes from the typical theme but I figured I'd post my parts list (with links) in the event anyone comes along in the near future it might take some leg work out in sourcing a full build.
Total build price around 650, give or take. The parts list totals around 600 but you'll need misc screws and boards (if building a case) from a local shop in addition to the shipping for the items in the list. I believe the only thing not readily available through my parts list is the shelf and trap door; which were 3D printed with PETG based on the previously shared shelf/door files. For anyone going this route - I've not had any problems with heat from the brass on the printed parts.
I'm thrilled with the results and am now working to find the ideal settings for my various brass. I've attached a couple images and here is a short video link for anyone curious.
Total build price around 650, give or take. The parts list totals around 600 but you'll need misc screws and boards (if building a case) from a local shop in addition to the shipping for the items in the list. I believe the only thing not readily available through my parts list is the shelf and trap door; which were 3D printed with PETG based on the previously shared shelf/door files. For anyone going this route - I've not had any problems with heat from the brass on the printed parts.
I'm thrilled with the results and am now working to find the ideal settings for my various brass. I've attached a couple images and here is a short video link for anyone curious.
Attachments
After some tinkering I think right around 5.2-5.3 seconds is the right amount for my 308 brass. The 750 isn't going too far beyond the shoulder and at 5.3 you can just see what the pink 1000 is turning at the shoulder. Now time to move beyond old 308 to more recent stuff. As others have mentioned, in the dark you can just see a slight glow start at 5.2. with the lights on I couldn't see the glow.
Is this about in line with other folks findings and I'm not majorly missing the boat?
Is this about in line with other folks findings and I'm not majorly missing the boat?
but they are worth every 0.1 second.We are all just guessing but in my view the necks on those cases are rather cooked. Notice how the color change for 750F on the case wall isn't materially different for any of them. For 1000F it isn't different for 5.1 and 5.2 seconds. I would move the case higher in the coil and repeat your tests. (Tempilaq changes color way before it goes black.)
It is nice to look at the annealed cases and see that there is a difference in colour after annealing, but do not expect this in every case. Every brand of brass has different metallurgy and that will affect the discolouring. The visual difference is incidental. What I believe is important is the use of Tempilaq 750, and as mentioned above, if you get the neck to 750 the shoulder will get what it gets. If you overheat the neck attempting to reach 750 on the shoulder you are going to over anneal the neck and the case will fail, usually with a split neck. The brass of the neck is a lot thinner than the on the brass of the shoulder, and therefore the neck will heat up a lot faster. And if you have neck turned you have reduced the thickness of the neck even further. Once brass is over annealed it is potentially dangerous and it belongs in the trash.
I had an idea that stems from a very basic understanding of physics and electronics so please bear with me. With steel tempering, I know one method is to heat until magnetic properties drop off as an indicator of proper temp. With induction heating, I know the amperage will drop around annealing temp for the same reasons. My question is, could we not measure this amperage drop to determine ideal time for annealing? Possibly how AMP Aztec is “analyzing”? I thought maybe this could work but have no idea how to test or measure this to get a useable result, or if this is even a useful data point. I could also be way out to lunch. Any thoughts?
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