Cleaning a blade without acetone.

[damianip]

Wrong on the grinding....grinding that would affect the flexibility of the blade is illegal....grinding to remove a wire or otherwise clean the groove is not. And U highly doubt any heat generated by a small diamond wheel's going to do anything to the flexibility of the blade....the wheel itself heats up too much, and only then if you sit on one spot for a bit.

Where is the "other grinding" permitted? I must have missed that.

The only mentions of grinding are in M1 (as already quoted) and in the weapons appendix where the direction of manufacturing grinding marks are specified as only permitted longitudinally (for the obvious reasons).

Grinding is grinding. If I missed the free pass on why it's permitted, I stand corrected, I just can't find it.

It doesn't affect the flexibility so much as created localized heat affected zones and possibly create small notches to provide stress concentrators which will in turn, cause blade breakage.

Paolo

[damianip]

You can definitely use a microtorch or heat gun to remove glues at temperatures that would not affect the temper of the blade. As far as grinding, would that include any form of sanding?

On what premise is this conclusion based? I could easily destroy a blade's temper with a micro torch and probably with a heat gun.

The grinding/sanding issue I addressed in another post. Grinding is highly accelerated sanding. The blade get plenty warm when being sanded, but the rate of removal is so slow, there is adequate time for heat dissipation.

This doesn't happen with grinding.

Paolo

[migopod]

On what premise is this conclusion based? I could easily destroy a blade's temper with a micro torch and probably with a heat gun.

The grinding/sanding issue I addressed in another post. Grinding is highly accelerated sanding. The blade get plenty warm when being sanded, but the rate of removal is so slow, there is adequate time for heat dissipation.

This doesn't happen with grinding.

Paolo

You could destroy the temper with grinding and heat guns or microtorches, but you would not necessarily is what I'm suggesting. If the heat is applied correctly the metal temperature would not need to be elevated to a sufficient temperature to remove the temper while still burning off the surface glue. Same is true of grinding with the appropriate sort of equipment, not applying a great deal of pressure and not remaining in the same spot for particularly long.

Like PF suggested, you can get hot spots if you bear into the grinder in one spot for very long, but if you just apply enough pressure to abrade off the glue and lightly rough up the surface metal, the blade shouldn't really ever even get warm to the touch, and no more material should be removed than would be removed with a vigorous sanding with a 60 grit abrasive or similar.

Edit: PF has mentioned before that when he uses the dremmel diamond cutoff wheel the pressure involved is generally less than the weight of the dremmel tool its self. Again it's possible to get a hotspot if you just let it sit there for a while, but I envision the process as lightly and briskly brushing the wheel over the glued area until the metal is clean.

I think it's a lot in the technique, and there's a definite risk of someone inexperienced screwing up the blade temper or nicking stress risers into the metal with a dremmel cutoff wheel. I'm just saying that it's not inevitable that the blade will get hot enough to remove the temper. Unless maraging steels can be screwed up at temperatures lower than 100 c, which is possible I suppose.

(FWIW, I'm totally an acetone man myself).

[damianip]

You could destroy the temper with grinding and heat guns or microtorches, but you would not necessarily is what I'm suggesting. If the heat is applied correctly the metal temperature would not need to be elevated to a sufficient temperature to remove the temper while still burning off the surface glue. Same is true of grinding with the appropriate sort of equipment, not applying a great deal of pressure and not remaining in the same spot for particularly long.

What I'm saying is that there is no way that someone can control this. If you assure me that you don't any make sparks, then you may have a chance of leaving the weapon metallurgically unscathed.

This is the reason for the rule, I suspect. It is much safer to say "No grinding" than "OK, if you do this just right and you're really lucky, then it might be OK"

Like PF suggested, you can get hot spots if you bear into the grinder in one spot for very long, but if you just apply enough pressure to abrade off the glue and lightly rough up the surface metal, the blade shouldn't really ever even get warm to the touch, and no more material should be removed than would be removed with a vigorous sanding with a 60 grit abrasive or similar.

I'm not addressing the amount of material removed (that's another can of worms), I'm concerned about the rate of material removal.

A high removal rate yields less heat dissipation which yields greater localized heating and uncontrolled cooling.

Edit: PF has mentioned before that when he uses the dremmel diamond cutoff wheel the pressure involved is generally less than the weight of the dremmel tool its self. Again it's possible to get a hotspot if you just let it sit there for a while, but I envision the process as lightly and briskly brushing the wheel over the glued area until the metal is clean.

It's much probable to get a hot spot and a heat affected zone that you might think. This is my rationale for simply not using a torch or grinding wheel on the blade.

I think it's a lot in the technique, and there's a definite risk of someone inexperienced screwing up the blade temper or nicking stress risers into the metal with a dremmel cutoff wheel. I'm just saying that it's not inevitable that the blade will get hot enough to remove the temper. Unless maraging steels can be screwed up at temperatures lower than 100 c, which is possible I suppose.

Right; and since the technique is out of the control of the USFA or FIE, the more prudent approach is to simply say, "Don't do it."

If you can tell me with utter confidence that the blade never experience temperature above 100º C, then I'm with you. However if the glue smokes at all, you're probably above it.

(FWIW, I'm totally an acetone man myself).

Me too. However, that requires some planning as well, but done properly is safe for the armorer and pretty much has no effect on the weapon (except for the cleaning).

Paolo

[migopod]

So I did a little experiment. There are a few caveats here. The blade in question is a BF blue maraging blade, so the grinder-spark relationship might be different than with a plain ol' carbon steel blade, but here's a quick video of grinding on it.

(it was already broken, so no worries about screwing up temper )
[youtube]http://www.youtube.com/watch?v=3y93_rA8HIQ[/youtube]
What I noticed was that even when I put as much pressure as I would be comfortable putting on one of those wheels to cut without breaking it, it didn't actually spark at all.

It did get a patina in the kerf, which would indicate having reached at least a surface temperature sufficient to start messing with temper, but for the rest of the grinding there were no sparks and the exposed bare metal was not discolored.

What I also noticed was that the groove at least up that close to the forte was narrow enough that getting into the glue might have required removal of some blade material, which I wouldn't have wanted to do with a blade that I was planning on using again, and for the amount of time and effort I would be willing to expend on rewiring a blade I'd have opted for the acetone bath given my druthers.

I use whatever generic CA adhesive I have around the house usually, and that plus acetone plus light sanding before gluing and I've never popped a wire yet.

[Purple Fencer]

So I did a little experiment. There are a few caveats here. The blade in question is a BF blue maraging blade, so the grinder-spark relationship might be different than with a plain ol' carbon steel blade, but here's a quick video of grinding on it.

I've found that FIEs generally spark less than carbons, although Vnitis tend to act like 4th of July sparklers sometimes.

It did get a patina in the kerf, which would indicate having reached at least a surface temperature sufficient to start messing with temper, but for the rest of the grinding there were no sparks and the exposed bare metal was not discolored.

You're also using a fibreglass cutting wheel. Try the experiment again with a diamond wheel (you can use more pressure throughout) and report your results as a comparison. You can't really use the fibreglass wheel in a foil groove...too narrow..works great for epees tho, if you're in a rush (I just started doing this for that reason....also because the groove in an Absolute non-FIE epee blade's just awful and NEEDS some cutting)

[Purple Fencer]

Where is the "other grinding" permitted? I must have missed that.

Again....grinding that is designed to change the flexibility is the issue (thinning the foible of the blade comes to mind)....cleaning the groove properly is NOT this type of grinding...I think Dan DeChaine and other top armorers would've told me if the diamond wheel was an illegal grind.

[damianip]

Again....grinding that is designed to change the flexibility is the issue (thinning the foible of the blade comes to mind)....cleaning the groove properly is NOT this type of grinding...I think Dan DeChaine and other top armorers would've told me if the diamond wheel was an illegal grind.

Sam,

Where is this in the rules? The rules say "No grinding". They don't say why.

I have my theories, but rather than guess the motivations and try to circumvent them, I would just rather not break them, especially if a blade goes through a "Lexan" visor after breaking.

The lack of sparking is a relief. However, the hardness of the abrasive may have something to do with it.

And yes, different alloys spark differently: it's chemistry, it's like magic!!!!

And yes, I tend to believe everything Dan DeChaine tells me as well (good reason to)...

Paolo

[migopod]

You're also using a fibreglass cutting wheel. Try the experiment again with a diamond wheel (you can use more pressure throughout) and report your results as a comparison. You can't really use the fibreglass wheel in a foil groove...too narrow..works great for epees tho, if you're in a rush (I just started doing this for that reason....also because the groove in an Absolute non-FIE epee blade's just awful and NEEDS some cutting)

I'll swing by the hardware store when I have a chance. I think I also have a non-FIE blade in need of rewiring. I'll see how the wheel works on that when I figure out which one it is that needs work on.

As far as sparking vs non-sparking, I don't know what Paulo's metallurgy street-cred is, and it's been quite a while since I did anything in the area, but my understanding is that while the removed material is tiny and hot and therefore sparkling, the base material is a good heat-sink and while perhaps the very surface may get hot from grinding, the bulk of the material doesn't get enough heat to affect temper unless you're using a lot of friction and pressure. So maybe a micron or so of the surface of the material gets de-tempered, but the structural element is unaffected.

Again, it's been a while since I did anything in the field, so I'm open to correction, but the FIE rule against grinding seems more applicable to removing material and changing the shape and cross-sectional area of the material than to affecting the temper of the blade. The dremmel cutoff wheel result was completely surface treatment, and except where I really put pressure behind it, didn't do anything that I'd consider remodeling of the blade.

That asside, has anybody ever attempted just sandblasting the groove?

[migopod]

Sam,

Where is this in the rules? The rules say "No grinding". They don't say why.

I have my theories, but rather than guess the motivations and try to circumvent them, I would just rather not break them, especially if a blade goes through a "Lexan" visor after breaking.

The lack of sparking is a relief. However, the hardness of the abrasive may have something to do with it.

And yes, different alloys spark differently: it's chemistry, it's like magic!!!!

And yes, I tend to believe everything Dan DeChaine tells me as well (good reason to)...

Paolo

By the way, the wheel I used in the video is the same one I used to cut the tang to length on another BF blue FIE. It definitely did spark while cutting the tang, but IIRC the tang isn't the same alloy as the rest of the blade.

[damianip]

By the way, the wheel I used in the video is the same one I used to cut the tang to length on another BF blue FIE. It definitely did spark while cutting the tang, but IIRC the tang isn't the same alloy as the rest of the blade.

Uh, no.

If it's not an LP then it is definitely the same alloy as the tang. There might be some slight difference in the heat treatment in an effort to make the blade "settable" (FIE blades are hell to set).

I'm not sure if LP uses different alloys in the tang versus the blade, but since they are brazed together, they may have that option.

Paolo

[migopod]

Interesting. I had speculated that LPs are forged in one piece from the end of the tang to about the first inch or so of the blade and then brazed or otherwise affixed to the folded sheet of blade and that most if not all other manufacturers forge the blade to the end of the square portion of the tang in one piece and then weld commercially available threaded rod and machine the weld area down prior to heat treatment of the blade.

This speculation was due to the question of why LP full-length fully-threaded epee tangs had a high rate of breakage inside French handles while other manufacturers were not as well known for doing so. Mostly cut threads on the LP vs rolled threads as would be the case for mass-produced threaded rod welded to the tang of another blade.

Admittedly I haven't seen the manufacturing process first hand. Is this speculation incorrect?

Maybe we need to lobby Discovery's How It's Made to do a segment on epee blades!


By the way, I was able to get some nice sparks from the BF blue using a 4" right angle grinder. I'll have to video it for fun.

[JacoKierkegaard]

Meh, I screwed around on a broken blade using the diamond wheel instead of the buffing wheel. It gets the job done too, but creates way more sparks, so given the discussions about heat affecting temper I think I'm going to stick with what I'm using. The aluminum oxide wheel wears down a lot more quickly, but since I'm only cleaning my own blades I don't mind.

[SensibleStu]

Interesting. I had speculated that LPs are forged in one piece from the end of the tang to about the first inch or so of the blade and then brazed or otherwise affixed to the folded sheet of blade and that most if not all other manufacturers forge the blade to the end of the square portion of the tang in one piece and then weld commercially available threaded rod and machine the weld area down prior to heat treatment of the blade.

This speculation was due to the question of why LP full-length fully-threaded epee tangs had a high rate of breakage inside French handles while other manufacturers were not as well known for doing so. Mostly cut threads on the LP vs rolled threads as would be the case for mass-produced threaded rod welded to the tang of another blade.

As far I i know this is the case, had 2 tangs break on my that were in french grips and was told they had just replaced the tang by brazing. They are two seperate pieces, fairly obvious if you look closly at the tang and the first inch or so they are seperate pieces to the rest (at least on the ones I own). Might ask the mech engineering dept to x-ray one for me to see