Dusting off the cobwebs

[RandallMoffett]

Mac,

I am just so impressed by the processes of heat treatment. So much goes into it beyond what the average person thinks of. Or at least beyond me.

Just amazing.

Really wish I had landed that job. I'd love to see this in person.

RPM

[Mac]

Randall,

I wish I knew exactly how much of this preparation is necessary and how much is overkill. Unfortunately, there is only one way to find out.

Mac

[Mac]

Returning to the question of whether of not the "feet" on the cullet brace are up to the task.... When I put a scale under the point of the tail, and get everything nice and level, it looks like there's a bit over 2 pounds that needs to be supported.



If I set things up another way, and put the scale under the toe of one of the feet, I get something closer to 3 pounds.



I think that the second set up is probably a more appropriate one because it takes into consideration the leverage the cullet has on the feet.

If we take a pessimistic view, it sounds like this. Whichever of the feet is really in contact with the kiln floor will experience a bending load of 3 pounds. If it yields at all, it will bring the other foot into contact and now the load will be shared between them. I suppose that we can say the bending load is probably at its greatest just above where the foot meets the leg. If that's not too great an oversimplification, then the angle iron will initially see a bending load of about 3# and a lever arm of about 5". If that is sufficient to bent one of the legs/feet, than the load will be shared between then and is now more like 1.5 pounds. If that is still enough too much for then and they bend further, the tail will come into contact with the kiln floor and some of the weight will be transferred there. Even in this scenario, I am still doing a lot better than not having the feet. So, I guess I will leave it as it is unless Sean thinks it's madness; in which case I will weld something between the toes and put a diagonal brace from there to the upper crosspiece.

Mac

(Edited to correct correct something I said that was patently stupid. With any sort of luck, not too many people saw the original)

[Mac]

All this weighing and guessing has brought my attention to another worrisome point. That is whether the cullet flange of the backplate is up to the task of supporting its share of the weight while everything is hot.

When I set the cuirasse up at the angle it needs to be in the kiln, and put the fauld flange on the scale I get a value like 7 pounds. The flange is pretty vertical, and it's just under .075" thick. I suspect that it will not be a problem.



On the other hand, the cullet flange is more like .040" thick and it will be seeing even more weight at something like 7.5 pounds. I am worried about this one.



Not only does that seem like a lot of weight to be born by thin steel, but it will involve a piece of kiln furniture like I show here.

[imghttps://lh3.googleusercontent.com/7Tur5T0jkrTOs_0j9mbQsRbqdiX3lWILRimeQStDZteX0ndoDjoOlyRhSmWhm8z_CifFRigrW2tRM25ei1Ms7hgBBKRR7HZdi9JMvIVF42ylT_1_8FCTdS6w-HkPGN3Fx742psbWpZMC4nNn3uMXPgiwNVUp3XlfXcKMwsWbHSuyBsCHt1_bqtLru5cAYHCwvlxPSOpLdWiK2dQvp33mo5gzbB7c26hSKXCEsKO1C82I7yLhO4nn-1nfB3K_YR2XZqCM0KsdeIsG6RfKXbldA9yDxqQxLRzK1SCaGH-345JK8DXJY_Fjm2BR9TlQ-0V-mje1NcefsxJrhfJnhHDRrCS6CW3wJ1TKqFZD0CyxmhOw-Jp2EMsSd0IbNOuc3erUkGP75HmJbiNmfqSe6u2dbmNvXlEsnVXYTI4PsZgTKy6Nb33D95f0P2fpWcpG19HYxMjWnnKb1FKrZ39Bx3kjCZItYXyvz1IKhbYA42rDbwG2r6tLsz5Xg6slpoaRYdt7ZvmaocX7zRvIZzEamDf7DTWRu-3SFKuuVlZvW70NCf8lDBDI2v6nu7VmLRugasM6uPPH9BbTsPDHgF74aSvJ4zqpQj2khceXuQyLIMFK7RD-GfkE=w582-h741-no[/img]

Settling the armor onto that furniture will not be too hard, but once the cuirasse is done I will have that ceramic column lying there and getting in the way of the next things to enter the kiln. I've had this sort of thing before, and it's pretty easy to reach in with the hook and shove the furniture over into a corner. But, that is one more damn thing to worry about, and it means that the breast and back must precede the skirts. That's because it's a lot easier to shove the hot object into a corner than it is to retrieve it from the corner and place it where it needs to be.

So.. I decided to make a sort of leg for the backplate to sit on. This will obviate the need for the kiln furniture and take the load off the flange by jacking it up and out of contact with the kiln floor. I welded a foot on the end of the leg to keep things stable, but kept it short to minimize the bending (and twisting) loads it must endure.



Mac

[Sean Powell]

Mac,

3lbs of force on the feet at orange is probably fine. It takes a fair amount of oomph with a hammer to move bar-stock in the hard direction when only at orange. But let me ask you this: 15 minutes to weld some extra bars in vs the time it would take to fix or rebuild the fauld if something went wrong.

Likewise, I'm loving the support piece for the back-plate. Makes me want to ask if you couldn't add 2 legs at the sides using the rivets that hold shut the over-lap and have them all support the front of the BP 1/4" off the floor. An hour building more supports for 100% assurance vs the time it would take to repair/replace in the unlikely event that it was needed and wasn't there.

I never admit to being more than 95% certain that something will go my way. If the cost of damage is 20:1 more than the cost of belt and suspenders, I add the suspenders to my belt.

Best I can do from a distance.

Sean

[Mac]

Thank you, Sean!

I was torn in two directions by your reply. On the one hand, I could play it safe and add more bracing. On the other, we both seem to think that it's probably strong enough. If I add bracing I am assured of it not failing through the brace bending, but we don't get much data from the results. If I go without additional bracing, there is a chance of the armor being compromised (but probably not ruined) if the bracing sags, but there will be a gain in information.

After deliberating this for a bit, I thought that I might be able to get some data without endangering the work. I hung a bucket of water with a weight of 3 pounds...



... on a piece of angle iron with markings at one inch intervals (to include the 5" that I figured the lever arm to be).....



.....and heated it up to orange heat with the torch. (the camera makes it look hotter than it was)



At the 5" mark, I could see no deviation. So, I increased the weight to 6 pounds and tried again. There was still no perceptible bending.

I then moved the heat to 7" with the weight at 6 pounds. I thought I could see a slight bend, but I was not sure how much was caused by the weight and how much was the result of unequal heating.

When I moved the heat to 9" (keeping the weight at 6 pounds) I definitely got some deflection. You can see it here under the ruler. (pay no attention to the scale on the ruler; I did not think to orient it with the true length from the chain)



I feel pretty comfortable now with the bracing of the cullet. I suppose that there is a chance that more prolonged heating will allow some bending, even at lighter loads than what the test showed, but I suspect that it will not be enough to matter.

I'll go have a look at the breast and back and see how feasible it seems to add another couple of legs like you suggested to get the whole flange up off the ground. I like the idea in principle, but I need to work out the details before I commit to it.

Mac

[Mac]

Here's my interpretation of Sean's recommendations for the breast and back. I bolted short legs onto the rivets which hold the upper and lower breast together at the sides, and then joined all three legs together with a sort of triangle. The legs protrude a bit beyond the triangle in case the floor of the kiln is not flat (it's not).



This took less than an hour and a couple bucks worth of iron. It seems like cheap insurance against having the flange get distorted by the weight of what's above it.

Mac

[Mac]

It's a heat treating day.

I'm warming up the quench and hotting up the kiln. When I get closer to the time, I'll heat up the "stop tempering" range as well. It turns out that the skirt pieces will fit in the range (just barely in the case of the cullet and all its bracing), so they will be the first things into the kiln.

The breast and back will not fit in the range, so I will have to hope that nothing untoward happens while I try to get the kiln down to tempering temperatures as rapidly as I think prudent.

Please think positive thoughts, just in case it matters. (No matter how hard we try, we just can't free ourselves of superstition. It must be hard wired in our brains)

Thanks!
Mac

[James Arlen Gillaspie]

I quench 1050 in oil, but I don't think you are using that, if I remember rightly. Oil quenching leaves you the option to play the big weed burner all over the piece (to keep the temperature as even as practical) till the oil smokes. This takes care of the 'glass hard stage', and old school watch and clock makers often tempered their springs this way. Putting the piece in the kiln afterward is insurance.

[Mac]

There is not option to burn off the oil here, James. The quenchant is an aqueous polymer.

I do use that method on small springs and punches though. Even if I quench in water, I wrap the part up in wire and dip it in oil so that I can burn it off.

Mac

[Mac]

So far, things seem to be going OK. I have both of the skirt asemblies hardened at around 1470° F, quenched, and then stop tempered with the range set to 450°.

I have some trouble getting them much above about 300°F in the range, but that aught to be enough for now.



The fauld looks good.



The only thing I have noticed is a certain gappyness in the front. This will not be a problem.



The cullet seems to have come out OK as well.



The free ends of the lames spread a bit, but that will be easy enough to fix.



I brought the breast and back up to about 1450°F before quenching them. So far as I can tell, it went well.



I have rinsed off the quenchant, but the range is not big enough to accept it, so it will just have to sit there while the kiln cools. There is a piece of kiln furniture propping up the lid a bit to speed the process, but is will take a couple of hours.



Mac

[Mac]

Today's heat treating seems to have gone well. I tempered all three pieces at about 750°F for 15 minutes to about a half hour.

The ends of the cullet lames, which had fanned out a bit in the hardening were easy to fix in the tempering. I used a C-clamp and a couple of small bits of steel to close up lames on each side, and put the armor into the kiln for the final tempering. This is a bit hard on the clamps, but they usually survive the process and only need to be oiled a bit to work again. Some of these little clamps have been through the tempering process six or eight times.




When the piece was cool and the clamps removed the lames were all nicely lined up again.



Here's a shot of all three pieces after the tempering. There will be a bit more correction to do on them, but most of that will be with a hammer.



Strangely enough, the last time I heat treated anything was on this same date a year ago.... a weird coincidence.

Mac

[Jeremy.G]

Congrats Mac! I know the fat lady hasn't sung just yet, but it looks to me like you're past most of the nerve-wracking part. . .

-Jeremy

[Signo]

Mac, I hope you feel how much the entire AA was with you on this process. I'm so glad it went all smooth, and I'm sure we all can't wait to see it polished assembled and weared for the first time.

[Sean Powell]

Here's my interpretation of Sean's recommendations for the breast and back. I bolted short legs onto the rivets which hold the upper and lower breast together at the sides, and then joined all three legs together with a sort of triangle. The legs protrude a bit beyond the triangle in case the floor of the kiln is not flat (it's not).

(PICS REMOVED)

This took less than an hour and a couple bucks worth of iron. It seems like cheap insurance against having the flange get distorted by the weight of what's above it.

Mac

That looks like quite the sturdy solution. For 1 hour and a few bucks in steel I'd have considered it a worthy insurance policy.

I want you to know that the last time I was this concerned about the success of something someone else was doing, my wife was going into labor. You really do a great job of keeping us nervously waiting.

Sean

[Tom B.]

This took less than an hour and a couple bucks worth of iron. It seems like cheap insurance... (snip)

Mac

As you have told me more than once

"Nothing exceeds like excess..."

As a mechanical Engineer, like Sean, I often have to do the same sort of effort vs risk evaluations.
I find it is usually worth doing the belt and suspenders.

[Kristoffer]

Thank you for the clamp tip. Very helpful. Also, congratulations for a successful hardening process
!

[Mac]

Thank you, Guys!

Mac

[Mac]

It looks like all the bracing held fine. The much debated feet on the cullet brace still have their original shape. They did not quite sit flat going into the kiln, and then still don't. I thought I might find that the one that was loaded more would sag, and they would end up bearing more evenly.... but no.

The 1"x 1/8" angle iron "bridge" that bore the entire weight of the breast and back is still straight and flat....



...in spite of having supported the entire weight of the armor and the other braces.



Of those 17 1/2 pounds, about 5 1/2 were the braces.



Everything is disassembled now, and I have started the rough grinding on the upper breast breast.



Mac

[Mac]

On a sombre note.... This is the one year anniversary of Will McLean's death.



It looks like his armor will end up with the Philly Museum of Art, as part of the educational material in the Arms and Armor dept. We are still working out the details.

There will also be some sort donation to the A and A dept in Will's memory by the charitable foundation that the McLeans administer. I will report when that is all finalized and can be made public.

Mac

[Jeremy.G]

That sounds like a fitting tribute.
My thoughts are with you, Mac.

[Mac]

I'm just grinding. There's not much to report.

I'll try to show some progress pics when there is enough progress that it looks like something.

Mac

[Ckanite]

Mac, there has been at least a half dozen times I was on edge watching this project but this last round with the heat treating gave almost gave me a sleepless night. Every time I've done a heat treating, I've had an error of some sort and I've never put as much time and love into things like you have. I once dropped a knife before tempering onto the floor... 10 hours gone. I almost cried.

[RandallMoffett]

What do you use to grind Mac?

[Mac]

Mac, there has been at least a half dozen times I was on edge watching this project but this last round with the heat treating gave almost gave me a sleepless night. Every time I've done a heat treating, I've had an error of some sort and I've never put as much time and love into things like you have. I once dropped a knife before tempering onto the floor... 10 hours gone. I almost cried.

Heat treating is certainly a risky business. I wish I had some better ideas about how to do it. There are a couple of small cracks on the body armor, and I will say more about them in a bit.

Mac

[Mac]

What do you use to grind Mac?

I'm pretty much doing the same things I did on the legs. There is a description of the processes starting on page 38 viewtopic.php?f=1&t=169445&start=1295

If I do anything different, I will be sure to mention it.

Mac

[Mac]

So... Today's irritation comes in the form of a small crack in the upper backplate.



As you can see, I took reasonable precautions with what was clearly a trouble spot, and left a nice radius at the bottom of the "V". That wasn't enough, I guess. I don't know if this would have happened if I had been able to temper immediately or not.

Here are closer views of both sides.



The prospect of welding in an area like this is very unappealing. Without perfect control of the cooling, it will just open again. To make maters worse, the metal it thin. Further, there is very little leeway for grinding the edge back if the weld is not good all the way out. I decided that the best fix would be to drill a hole at the end of the crack and fill it with a bit of rivet wire.



Here is what it looks like after a bit of rough grinding. (sorry about the focus)



I got the neck plate back in there as to keep the shoulders from flexing while I do the rest of the grinding. Note that I have sharpened up the crotch of the "V" to look nice. Now that the armor is tempered, stress concentration is not as much of an issue. In fact, I'd almost prefer to make an new stress concentration in someplace that I know to be sound and hope that it takes some stress off the end of the crack.



Mac

[Jeremy.G]

ACK! Irritating indeed. Looks like a solid fix, though.

Again- many thanks for sharing the setbacks as well as the successes. This is gold...


-Jeremy

[RandallMoffett]

How do you get into those complex flutes where two or more converge Mac? Are you really able to get into that with those pads?

Sorry about the crack. That is just a pain. Hope it works how that is.

RPM

[Mac]

How do you get into those complex flutes where two or more converge Mac? Are you really able to get into that with those pads?

The important thing is that when two flutes intersect, one of them is effectively "above" the other. Here is where the center back spray meets the armscye flutes. The relevant edge of the second armscye flute is a "half flute". This makes there be no unreachable "pockets"
at the intersection. This sort of arrangement is typical of real armor.



Does that make sense?

Mac

[wcallen]

How do you get into those complex flutes where two or more converge Mac? Are you really able to get into that with those pads?

The important thing is that when two flutes intersect, one of them is effectively "above" the other. Here is where the center back spray meets the armscye flutes. The relevant edge of the second armscye flute is a "half flute". This makes there be no unreachable "pockets"
at the intersection. This sort of arrangement is typical of real armor.



Does that make sense?

Mac

I need to take some more pictures, but this shows an authentic piece with "intersecting flutes" at least sort of. The idea is the same. Mac is 100% right, one is above the other:

http://www.allenantiques.com/images/A-283-back.jpg

There aren't as many flutes, and they aren't as aggressive, but you can see some examples of the same thing on the cuff and side of the back of hand on these:

http://www.allenantiques.com/images/A-98-new.jpg

That doesn't make the work to actually create the piece easy, it just makes it possible to grind.

Wade

[Zubeydah]

I don't make armor. I don't wear armor.
But as someone who loves art, artistry, craftsmanship... I *really* enjoy following this thread.
Thank you, all - it is a joy to see such beautiful work, and the collaborative thinking that happens, and the inspiration that happens. It's just.. yeah. Awesome.

[Mac]

Thank you, Ma'am!


Mac

[Mac]

The last couple of days I've been grinding the breast and back, and I have the parts at 180grit (more or less). There were quite a few places that needed a bit of hammering to bring the surfaces up level enough to grind. That tends to produce a sort of curling in of the lames. Also, the act of grinding off a few thousandths of an inch can allow things to warp a bit. In addition the fleur on the point of the lower breast had too much clearance, and it defied my attempt to bring it in with local heat. All of this leads to the idea of putting the armor back into the heat treating braces and tempering it again. I knew there was a strong possibility that I was headed this way, so I have not yet plugged up any of the temporary holes I made in the overlaps.

Here is what it looked all braced back up. And here it is after a half hour at 750°F



The oxidation is a thin blue/grey, and I expect it to come away easily enough when I resume grinding/polishing. Right now, I'm out of 180gr belts and must wait for the new ones to arrive. I ordered on Saturday. If I had been clever, I would have taken stock or my abrasives last week and ordered then.

Mac

[RandallMoffett]

Hmmm. That is interesting. I had not thought about that before but all the imagines I was looking at I took at the RA that is also the case. Very interesting. Well that makes sense then. That is actually very helpful!

RPM