GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: MartyMcFly on February 23, 2021, 02:24:11 PM
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While doing research for spring guide materials I came upon a ceramic alloy called BAM. It's a mix of aluminum, boron and magnesium. I'm not planning to use it to make guides but the thought of using it as a coating (a few microns) inside a springer's compression chamber or perhaps on the contact points between the piston and compression chamber would make using lubes (like Krytox, Molly et al) superfluous and produce better results.
This stuff has half of the coefficient of friction of Teflon (0.02 vs 0.05) and is only second in hardness to diamond. It is available in powder form. The question I have is how does one apply this type of material to steel and ensure that it bonds well? Anyone in the industry know how its done?
-Marty
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Have no knowledge about this dry lube. Sounds interesting.
One concern would be flash temperature, if you egnight magnesium, you can't extinguish the fire.
Think vintage camera flash bulbs.
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That one sounds interesting. I burnish molybdenum disulfide powder into my compression tube, piston, and seal. The powder is compatible with Krytox so I use that, too. If I recall correctly, tungsten disulfide is an even better lubricant.
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Have no knowledge about this dry lube. Sounds interesting.
One concern would be flash temperature, if you egnight magnesium, you can't extinguish the fire.
Think vintage camera flash bulbs.
If my research is correct this stuff has a melting point of over 2400 degrees Kelvin (close to 3800 Fahrenheit), so I think we would be safe on the flash/combustion danger.
-Marty
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That one sounds interesting. I burnish molybdenum disulfide powder into my compression tube, piston, and seal. The powder is compatible with Krytox so I use that, too. If I recall correctly, tungsten disulfide is an even better lubricant.
Thanks for mentioning Tungsten disulfide - just looked it up, its coefficient of friction is real nice at 0.03 (lower than Teflon, Graphite and Molybdenum disulfide). And all you need is 1 micron of the stuff with very high temp resistance. Prices of Tungsten and Moly supposedly have become close to equal recently... hmmm, more research needed.
-Marty
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I'll be following 🎫
+1. 👍
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Thomas, when you burnish the Moly into the compression tube, do you do any special preparation to its surface? I was thinking that with dry powder lubes it makes sense to have micro abrasions in the surface in order for the powder to have a place to lodge itself to prevent it from slushing-off the surface...
-Marty
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So I've been doing some comparisons to guess what this BAM compound might be capable of relative to others. Looking at some engineering references I found the following static coefficient of friction numbers for steel against said compounds
Steel on Steel (clean) = 0.8
Steel on Brass (clean) = 0.35 - 0.51
Steel on Steel (traditional lubricant) = 0.16
Steel on Moly grease = 0.11
Steel on Graphite grease = 0.07 - 0.1
Steel on Teflon/PTFE = 0.04 - 0.05
Steel on Nylon = 0.4
Steel on Rubber = 0.64
Steel on Polyethylene = 0.2
Steel on Tungsten Disulfide = 0.07 - 0.09
Given BAM's coefficient of 0.02 it could probably get a 0.03 - 0.04 static coefficient on steel and of course the dynamic/sliding coefficient could be as low as half that...
Now the question is how it should be applied. I like the burnishing approach because its simple and cheap however, there is probably a cheap way to atomize the stuff to really get a good long-term coating on steel - just haven't figured it out yet.
-Marty
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After some more research I've come-up with a DIY plan that I think can be used on Tungsten Disulfide, Moly and BAM powder (your pick). I would not use this on the grease versions of these compounds since they have other additives.
1. Degrease the compression tube with alcohol or equivalent.
2. Prepare the surface area by lightly sand blasting the inside of the compression tube with 5-micron aluminum oxide powder or use the alumina powder on a dowel wrapped in microfiber mounted to the end of a drill to lightly burnish the inside of the comp tube.
3. Clean out all of the alumina powder with alcohol.
4. Mix the chosen lube powder with isopropyl alcohol to create a paste and apply it to the inside of comp tube. It should be spread uniformly but not too thick, then let dry.
5. Apply the same paste to a dowel wrapped in microfiber and let dry. You could also use a small buffing wheel (Dremel) with extension to get into the tube.
6. Buff the inside of the dried comp tube with the wrapped dowel. If done properly the inside of the comp tube should be a grey color if using the Tungsten or Black-ish if using the Moly. Ultimately we want the minimum amount of the this stuff on the comp tube while allowing it to work its way into the micro abrasions within the steel's surface.
7. Clean out the comp tube with alcohol again. Done!
Full disclosure - I have not yet done this myself, but I plan to once I get some of these powders and make some free time. The biggest question I have is the longevity and real world benefit of these powders versus just having an untreated comp tube with a little Moly around the back of the piston seal. I guess some testing will be in order.
-Marty
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Yes ... sarcastic with a smile ;D
Would not shooting a PCP be a whole lot less work and frustrating ?
Tho on this note, the smoothest shooting and most consistent spring piston guns I've ever built have been those that assembled with Tight tolerance having buttoned or wear ringed pistons, well fit piston seals and spring guides with a liner in piston running on a OIL FILM only !! Not a stitch of Grease, moly or tar anywhere in the firing mechanics.
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Yes ... sarcastic with a smile ;D
Would not shooting a PCP be a whole lot less work and frustrating ?
Tho on this note, the smoothest shooting and most consistent spring piston guns I've ever built have been those that assembled with Tight tolerance having buttoned or wear ringed pistons, well fit piston seals and spring guides with a liner in piston running on a OIL FILM only !! Not a stitch of Grease, moly or tar anywhere in the firing mechanics.
Motorhead, I agree with you. If you just want something with superior shooting characteristics then PCP is the way to go. That being said, this is a hobby for me and having the pleasure of discovery and making something better beyond its OEM form gives me some satisfaction. I'm sure you know the feeling ;D
In a perfect world with unlimited money I would have myself a super tight tolerance springer. Fully optimized using computer simulations and using the latest materials and space lubes... but this is just a hobby so I'll settle for what I can do at home.
-Marty
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I was trying to help honestly .... my last part of above post was some key info if you can do so ;)
Yes we all have fun tinkering and doing what we can with what we have to work with.
As you were Sir 8)
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Finely divided metals (airfloat) will burn fiercely at low ignition temperatures. Most materials considered non-flamable if finely divided will also burn vigorously. For examples, search for pyrotechnic compounds.
Have no knowledge about this dry lube. Sounds interesting.
One concern would be flash temperature, if you egnight magnesium, you can't extinguish the fire.
Think vintage camera flash bulbs.
If my research is correct this stuff has a melting point of over 2400 degrees Kelvin (close to 3800 Fahrenheit), so I think we would be safe on the flash/combustion danger.
-Marty
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I was trying to help honestly .... my last part of above post was some key info if you can do so ;)
Yes we all have fun tinkering and doing what we can with what we have to work with.
As you were Sir 8)
Motorhead, I took no offense to your initial post and I hope that my reply didn't sound stand-offish, it is so hard to convey the tone of speech in text. I always take your advice seriously and appreciate the help. And again I agree with you, I think a properly put together rifle should need the minimum of lubrication and that many guns come over-lubed to hide mass production deficiencies.
As with most of my ideas this one came up when I was researching "self lubricating" materials. I have an LGU that has a very loose fitting spring guide + top hat and I'd like to make replacements. The original part looks to be Delrin and so I began research on "better" replacements, which led me to stumbling upon BAM and the various other powder lubes that can be impregnated into plastic materials. As rabbit holes have a way of digging themselves I began to wonder how much of an improvement there would be if I burnished the comp tube with one of these powders and here we are...
Well, I've rambled enough... thanks for joining the fun!
-Marty
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Finely divided metals (airfloat) will burn fiercely at low ignition temperatures. Most materials considered non-flamable if finely divided will also burn vigorously. For examples, search for pyrotechnic compounds.
Have no knowledge about this dry lube. Sounds interesting.
One concern would be flash temperature, if you egnight magnesium, you can't extinguish the fire.
Think vintage camera flash bulbs.
If my research is correct this stuff has a melting point of over 2400 degrees Kelvin (close to 3800 Fahrenheit), so I think we would be safe on the flash/combustion danger.
-Marty
Yes, I get what you are saying. With fine powders there is a danger of combustion. This is the reason I don't necessarily want a film coating of the stuff on the comp tube walls. There is certainly a concern that as a film on a smooth surface most of it would slush-off with repeated piston strokes and provide aerosolized fuel in the compression chamber (BAD!!!). This is why I like the idea of burnishing it into micro sized abrasions in the steel, that way it stays put. Another idea I had is to only treat the backwards portion of the comp tube. This would reduce initial piston stroke friction while keeping it safe from the heat/pressure that builds up in the forward portion of the compression chamber.
-Marty
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Great idea, Marty. I was just wondering if dust would light off in the heat caused by air becoming a plasma like dieseing but brisiant enough to burst a tube?
Finely divided metals (airfloat) will burn fiercely at low ignition temperatures. Most materials considered non-flamable if finely divided will also burn vigorously. For examples, search for pyrotechnic compounds.
Have no knowledge about this dry lube. Sounds interesting.
One concern would be flash temperature, if you egnight magnesium, you can't extinguish the fire.
Think vintage camera flash bulbs.
If my research is correct this stuff has a melting point of over 2400 degrees Kelvin (close to 3800 Fahrenheit), so I think we would be safe on the flash/combustion danger.
-Marty
Yes, I get what you are saying. With fine powders there is a danger of combustion. This is the reason I don't necessarily want a film coating of the stuff on the comp tube walls. There is certainly a concern that as a film on a smooth surface most of it would slush-off with repeated piston strokes and provide aerosolized fuel in the compression chamber (BAD!!!). This is why I like the idea of burnishing it into micro sized abrasions in the steel, that way it stays put. Another idea I had is to only treat the backwards portion of the comp tube. This would reduce initial piston stroke friction while keeping it safe from the heat/pressure that builds up in the forward portion of the compression chamber.
-Marty
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This appears to be complex CERAMIC COATING that can be applied and bonded to a substrate by pulsed laser deposition or sintering. The discussion of applying this as a home tune lubricant like a grease, molybdenum disulfide powder, or tungsten disulfide powders has me baffled.
https://en.wikipedia.org/wiki/Aluminium_magnesium_boride (https://en.wikipedia.org/wiki/Aluminium_magnesium_boride)
YES, the material does have some impressive characteristics and it MIGHT be useful on some springer parts during manufacturing. That depends on the added cost of the material and its application process. It also depends on how much it actually improves performance over the more common lubrication materials. I'm skeptical that it can make a "significant" difference when used inside a springer.
https://en.wikipedia.org/wiki/Friction#Approximate_coefficients_of_friction (https://en.wikipedia.org/wiki/Friction#Approximate_coefficients_of_friction)
https://www.lowerfriction.com/pdf/8.pdf (https://www.lowerfriction.com/pdf/8.pdf)
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This appears to be complex CERAMIC COATING that can be applied and bonded to a substrate by pulsed laser deposition or sintering. The discussion of applying this as a home tune lubricant like a grease, molybdenum disulfide powder, or tungsten disulfide powders has me baffled.
https://en.wikipedia.org/wiki/Aluminium_magnesium_boride (https://en.wikipedia.org/wiki/Aluminium_magnesium_boride)
YES, the material does have some impressive characteristics and it MIGHT be useful on some springer parts during manufacturing. That depends on the added cost of the material and its application process. It also depends on how much it actually improves performance over the more common lubrication materials. I'm skeptical that it can make a "significant" difference when used inside a springer.
https://en.wikipedia.org/wiki/Friction#Approximate_coefficients_of_friction (https://en.wikipedia.org/wiki/Friction#Approximate_coefficients_of_friction)
https://www.lowerfriction.com/pdf/8.pdf (https://www.lowerfriction.com/pdf/8.pdf)
Mike, I did not say in my posts that this DIY method is an optimum application, thus the reason for my original inquiry. I think we are all conscious of the fact that pulse laser and vapor based methods are out of the reach of a DIY setup. That said, I don't think it would hurt to try a DIY method like burnishing, which works for Moly and Tungsten disulfide to an extent.
I don't expect it to be as effective as sinthering, but its hard to tell if its a waste of time without trying.
I'm a realist and if I had to guess I would say its not likely it will be perceptible versus something like Krytox or Ultimox on the piston contact points. BUT, its fun to try and if we don't try we won't know for sure. By the way although my initial inquiry was about BAM I think including Moly and Tungsten Disulfide powders in an experiment would still be enlightening.
Another application that is not mentioned is in the barrel to reduce pellet friction. I think most people have stopped putting Molybdenum disulfide on their bullets because it was oxidizing into an acid in the barrel, but BAM might not have that property...
-Marty
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Marty, I know I am late to the party :), but
1. Ask the manufacturer or supplier of BAM how to apply it, then decide if burnishing might work. A little research suggests plasma vapor deposition is typically used to fuse BAM to steel. See video below.
2. As for burning, I think the boron has already oxidized the magnesium and aluminum. It is like alumina abrasive - aluminum already in the oxidized state.
3. Inside a "springer", the high pressure and temperature is only present in the last 1 mm of piston travel. How much BAM powder might be swept there by the piston seal and burnt (assuming I am wrong about #2, above)? It would not seem enough to explode. If the powder is that loose, then the lube won't last long. From the sounds of it, even if all the BAM you applied were pure magnesium powder, it is probably not enough to do more than melt your piston seal.
https://www.youtube.com/watch?v=797eG7wPYj4 (https://www.youtube.com/watch?v=797eG7wPYj4)
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the smoothest shooting and most consistent spring piston guns I've ever built have been those that assembled with Tight tolerance having buttoned or wear ringed pistons, well fit piston seals and spring guides with a liner in piston running on a OIL FILM only !!
Scott,
Would you be willing to share what type of oil you used for this? Also, the airgun, or power level?
Thanks
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Marty, I know I am late to the party :), but
1. Ask the manufacturer or supplier of BAM how to apply it, then decide if burnishing might work. A little research suggests plasma vapor deposition is typically used to fuse BAM to steel. See video below.
2. As for burning, I think the boron has already oxidized the magnesium and aluminum. It is like alumina abrasive - aluminum already in the oxidized state.
3. Inside a "springer", the high pressure and temperature is only present in the last 1 mm of piston travel. How much BAM powder might be swept there by the piston seal and burnt (assuming I am wrong about #2, above)? It would not seem enough to explode. If the powder is that loose, then the lube won't last long. From the sounds of it, even if all the BAM you applied were pure magnesium powder, it is probably not enough to do more than melt your piston seal.
Always appreciate your input!
I haven't spoken to a supplier yet but most of the stuff I've read have pointed to laser vapor deposition as being the standard method of application for such alloys. That said I'd be willing to try the DIY burnishing method just for the heck of it. Maybe even go lower tech and just use a scotch-brite pad to make the micro abrasions before going down the alumina abrasive path. If the acquisition cost is not prohibitive I plan to apply it just in the areas where it might do the most good. So as you suggested I would avoid the last 1mm of tube, since the benefit there is going to be inconsequential to the backward force of the compressed air acting on the piston - or so I guess.
-Marty