Induction annealer

[itchyTF]

Finally got it done! Well, sort of.

It obviously needs a top and rear cover. In the top view the control board on the left side is my design and uses a microcontroller for timing, sensors and solenoid control.

Right now it functions as a one at a time device (by hand). My intention was to design an auto-feed but I lost access to a friend's mill. I was going to have a vertical tube to drop the cases in and at the bottom there would be a pusher activated by a solenoid. There would be a sensor to detect the presence of a case. In the "burn" position there would be another "case present" sensor and a solenoid to enable the case to drop.

The sequence would have been - if a case was present in the "burn" position the annealer would turn on for a preset time (set by the thumbwheel in the upper right corner up to 9.99 seconds). After the burn, the solenoid would activate dropping the case. If there was a case in the "magazine" the solenoid would activate pushing it such that it drops down through the coil then activating the other sensor starting the burn. The feed solenoid would retract getting another case in position. The system would continue emptying the magazine (but you would continue feeding it). As it's currently configured, it only takes about 1.2 to 1.3 seconds to heat the neck of a .223 to melt 750 deg. Temilaq. The heat marking doesn't look like new Lapua cases but it did reach 750 deg. Maybe part of it was the camera flash.

The toggle switch in the up position lights up the green LED and allows burn time changes. In the down position the green LED goes out and locks out time changes and continues using the last setting. Not really necessary, but what the heck it's only software.

I haven't loaded any yet to see how the seating feels.

I purposely left one in longer to see the effect. Didn't take long, maybe 3 seconds or so.

I haven't gotten around to my other cartridges yet (.20 Practical, .22-250, 6mm-250, 6x47L, .243AI and others).

 

[stumpm2]

Looks good. How much $$ do you estimate you have into it?

 

[Hedge]

I'm curious about the actual softness of the necks, now. The annealed part shows dull in the pic.
Normally,when using a torch, this would indicate an over-annealed condition. Do those cases have any spring-back?

 

[bozo699]

ItchyTF,
Nice looking annealer, I was talking to Tom M and Leo A of our 1000 yard club in Missoula Mt about building us one like your's, I just haven't got around to it yet. Looks like you had a good concept and transformed it into reality, nice job my friend, congrats on a nice annealer
Wayne.

 

[NZVarminter]

Yeah I've been thinking of trying to use induction rather than flame. I built a rotating carosel style using gass and it works really well, but with induction you could control (and measure) the temp accurally, though I havnt got any complaints about how mine are annealing. Its so simple I anneal as the first step in every reload now.

There is a thread here with one post showing there induction annealer, which uses one of the commercial induction heating kits for freeing up rusty bolts etc.

http://www.fishnhunt.co.nz/forum/YaBB.cgi?num=1280438526/33#33

The limitation with this style of induction heater is its a coil, so you have to lower the coil over the case, or drop the case through the coil.

When researching I found another commercial unit that has a cutout in one corner and you can hold the object in the corner rather than a coil wrapping around the object. if you could use this style of indcuction current then you could mount two opposiong coils over a carosel and just pass the case through the current, which would simplify the automation process.

Biggest challenge for me will be building the electronics side of it so I might have to wait till the price of hte commercial units comes down.

Cheers

Grant

 

[Jeffvn]

nicely done; I too am currently annealing with gas but waiting for induction to catch up so I could make teh switch to that technology.

Jeffvn

 

[jscandale]

What a great concept. I often thought that induction would be a better alternative to an open flame, but never really knew enough about how to make an induction coil, but you certainly do! If you can automate that thing and put a shield around the coil, that would be the cat's pajamas!

JS

 

[bozo699]

ItchyTF,
What kind of wire did you use for your heating element? and how did you wrap it so tight?
Wayne.

 

[itchyTF]

I would love to take credit for ALL of the heater but my head wouldn’t fit through a doorway. Instead of starting from scratch I bought a “kit” which included the main board with components mounted, a ferrite transformer with primary already wound, 2 heat sinks, circuit breaker, pushbutton and enough #4 wire to wind the secondary (3 turns). I added the base plate, covers, phenolic piece where the work coil attaches, 2 other phenolic pieces to mount the transformer, toggle switch, thumbwheel switches, 2 LEDs, circular connector for rear panel for sensor and solenoid wires (not mounted yet), control circuit board, 12v wall-wart, software development and all the labor for drilling & tapping and making holes to mount everything. The commercial “kit” was about $325. Can’t tell you off the top what my parts cost, but my labor at $1,000/hr…………………

One particular pain was the 4 switching transistors were already soldered to the main board but they are supposed to be mounted to one of the heat sinks. The transistors have to be flat to the heat sink and that’s hard to do with them already soldered. First I had to figure out where the mounting holes had to be, unsolder them, mount them to the heat sink with thermal pad then solder them back to the board. Took a bit longer than I would have liked. Details, details. Won’t bore you any further.

I wanted to do an induction type because I didn’t want to deal with open flame and I wanted something that was easier to set up and be more precise and repeatable. I will only have to establish the time to heat each case type once and record it. So the next time I want to anneal the xyz case I just dial in the corresponding time and that’s it. May have to change the work coil but that’s just 2 set screws. You can’t use the heat crayons or liquid with open flame unless you do it inside the neck but that doesn’t help for the rest of the case body. You can use this stuff on the exterior with induction heat. What I think I need to do is get a higher temp liquid to make sure it doesn’t go beyond it. Anybody know what the upper temp limit is supposed to be? I wanted to be able to do precise timing so my setup has a resolution of .01 seconds. I have 9 more control boards if anybody is interested. Software can be changed to meet your needs (within limits).

Since I haven’t seated any bullets yet I can’t say anything about them being too soft. I tried using some needle nose pliers on the neck of once fired LC brass (not annealed) and it didn’t take very much for it to take a set. Not a good way to measure. I got about the same feel on one of the necks in the picture. The difference in color may be partially due to the nature of open flame, don’t know. In the beginning of my experimentation, I heated one to a pretty good red and it was so soft I could squeeze the neck with my fingers. When that 750 deg liquid changes color I can’t detect any redness in case color in a darkened room.

I’m still experimenting with coil diameter and number of turns on the work coil. I’ve been using #10 copper wire with drill bits as a winding mandrel but thought of trying some small copper tubing (flattened). I wanted something smaller than ¼” which is all Home Depot had.

 

[amamnn]

I've been using an Induction Innovation hand unit for over 3 years now and noticed one or two thing that might be of interest.

1. The case color following annealing will be different since the surface effect is mostly eliminated when not using a slow flame like propane (even with the double torch annealer I had used previously) People have told me that other gasses work a lot better,faster than propane, but I have not seen any examples that proved it.
2. Annealing happens much quicker using induction than with flame (see above) with a few exceptions. --It seems large masses of metal in contact with, or in very close proximity to, the coil or the metal to be heated (like a case being held in a steel clamp or on a rod) will seriously affect the process. Certain cases that I regularly anneal have proved this rule - at least to me. .22 BR and .243 WSSM cases take longer to cook than 30 BR cases. Most all the short fat cases are slower to cook than the old fashioned long cases.....

3. Despite the above, I have found that quenching the cases is unnecessary.


I've seen another design for a machine annealer for individual use that looked promising, but the inventor abandoned it when he ran out of money trying to make it inexpensively enough to sell at a profit. It was quite similar to the OP's pix and description.

 

[Keith Glasscock]

Out of curiosity, how much energy does it absorb? What are you powering it with?

I've considered making an induction annealer, but I don't have teh electrical expertise to even know if it is practical to do.

 

[Nomad47]

I was hoping to see a lower cost. But I guess nothing is cheap anymore.

I live and travel in a motorhome and I anneal by torch one at a time manually. Induction would certainly work better for my situation.

 

[Scott Harris]

Couple of questions based on my own efforts using a Miniductor. Here are the problems I ran into with the Miniductor:

The unit overheats relatively quickly so volume annealing is out of the question
The coils burn up relatively quickly requiring replacement
The brass must be very consistently positioned in the dead center of the coils to get uniform annealing: I used a sawed off Lee press to achieve this.

Can you discuss how your device addresses these issues? I'd love to use induction annealing, but the miniductor is not the answer. I know brass makers use induction, but those gotta be very expensive equipment pieces

 

[itchyTF]

Busdriver - at my current experimental stage (size of work coil and .223 cases) it pulls about 500 watts. Powered with standard house power (117vac).

Nomad47 - Hoping to see a lower cost - me too!

Scotharr - with the current configuration this unit heats a .223 case quickly but the duty cycle is fairly low so the heater doesn't get too hot. If you have shorted turns on the work coil, that may be the cause of short coil life. I notice if the case is a little off center the field will cause it to center by itself although I plan on having a recess for the head to sit in thereby centering it. I'm still experimenting with coil material, length and diameter but I think the results are promising so far. I just placed an order for 800 and 850 deg liquid so I can get a better idea what my temp is. I used the 400 on the body of the case and it never changed color.

The parameters of the Miniductor may not be optimized for cartridge annealing. Don't know anything about its innards.

 

[BuffaloBill]

itchyTF,

That's pretty cool! Is the power supply operating in a forward converter mode? I'm guessing the secondary is isolated from the mains?

A fellow engineer here, Bill

 

[BuffaloBill]

P.S. I think I recognize the digital potentiometer you used. I might have some in a drawer at work!

 

[itchyTF]

BB-

It utilizes a Royer oscillator and the secondary is isolated.

The thumbwheel isn't really a pot but a BCD switch. I wrote the code to convert the 12 bits to seconds, tenths and hundredths.

 

[Steve Blair]

Induction heating is an extremely well explored industrial area. Most problems associated with coil life, efficiency and cooling requirements were solved a long time ago. No induction coil will exhibit any longevity without cooling, the reason why most are made from tubing with internal coolant recirculation. There are some relatively small units available with integral coolant, but they are not cheap. Acquiring the unit alone is not enough, the induction coil must be properly designed and a heat exchanger provided. Short of taking this more expensive approach, an endless series of burned-out coils is the most likely scenario.


http://www.ameritherm.com/PDFs/411-0050-10.pdf
http://www.inductoheat.com/articles.php

 

[sstkmkrr]

Please give me a call! Steve in Yuba City 632-9445

 

[243winxb]

Annealing-Old method

This is not the way to do it. Had strange results from to soft brass, i think. :-\ Annealing is best left to the brass manufacturers , as it needs specialized equipment to do it correctly. A misfire can be caused by improper annealing. When the shoulder becomes to soft, the firing pin strike can set back the shoulder. If the round fires, the brass expands, leaving no evidence of set back. I was shooting 223 Federal brass on its 6th loading. Having cracked necks, i decided that annealing might get a few more firings out of the brass. Even tho 40 years ago, annealing did not work on some 243win brass, making the necks to soft. The 223 misfire would not fire on the 2nd strike from the firing pin. At home, measurements show the shoulder was set back .014" when measureing to the datum line. L.E. Wilson's case gage shows the brass head below the lowest step. All loaded rounds had been gaged before firing. More testing was needed. Took 3 annealed brass with used primers and chambered them. After 2 strikes with the firing pin, shoulder set back was between .010" & .012" The used primer already had the firing pin dent in them, so the blow from the pin was not as great as new primers. The primer involved in the misfire was placed in a different non-annealed piece of brass. It did fire on the 2nd firing pin strike. A total of 4 hits on the primer, till it fired. I feel the primer may have been damaged from the first 2 misfires. Savage Axis bolt action 223 less than a year old. 722 rounds fired. Loaded with IMR4198-20.5gr-CCI400-Win. 55gr FMJBT-Federal brass-RCBS Dies made in 2010. There are Annealing Kits available & temp sticks that may help. But when you overheat the brass, there is no way to fix it. 3/28/12