How to attach stainless wire mesh so it doesn't fray?

Hey all, I’m working on the trommel I was talking about in this other thread.



I now need to figure out the best way to attach stainless wire mesh so that it won’t fray over time. A couple hundred pounds of sawdust will be rolling around inside the machine, and at some points I can’t avoid the mesh needing to have holes to allow the support spars to connect through to hold the outer layer of screen. Obviously, I’m not going to put holes in it where I don’t have to – but the dual chambered nature of the machine means that the inner layer of mesh has to have some holes in it.

I’m worried though, about the mesh fraying over time like cloth would.

So first, is this an issue I need to be worried about? The mesh will be pinned between a traversing piece of angle iron and a radial hoop of flat bar. Doesn’t it seem like, over time, the wire mesh will fray? Or perhaps the stiffness of the stainless wire threads (60 mesh and 30 mesh) will mean that won’t be a problem like it would with cloth?

Second, what can I do to minimize the effect? I need 14mm holes in it for the spars to pass. I was planning to punch the holes on a bench punch, figuring that’d be the cleanest cut I can make. Would it be worth trying to braze around the hole after (or maybe before?) I make it – kind of like paper hole protector rings you use in a binder? Or, I was also wondering about using an external tooth lock washer against the mesh, figuring its teeth might kind of grab on to the wires and spread the pulling load, so it’s not as easy for individual wires to fray.
Or another idea – could I use my cnc plasma to cut the holes, assuming that the cut is going to fuse the ends of the wires together? (Perhaps with a sacrificial backing piece of stainless sheet metal?)

I looked around online for ideas on best practices for affixing wire mesh cloth, but most of what I found was for much bigger, heavier cloth where you can put a bolt through the (much larger than mine) holes that are already in the mesh.

You can crimp grommets into the holes or cut the holes with a torch and weld the edges.
Bill D.

Farm King- Grain Cleaner

I'm seeing bands....

An approach that doesn't disturb the mesh might be a worthwhile "thought experiment".

Make the spars in two parts, 'top' and 'bottom'. Bottom spar holds inner mesh, top spar holds outer mesh. Spars are hollow, stacked, and set diametrically opposed to the pair on the other side, as needed. Spars have spikes on, say, 2" washers/plates, that 'mesh with the mesh' it's supporting. (Bigger washers=more stable spar.) (Spikes go into recesses of mating washer/plate, so it fully penetrates and locates mesh without cutting any wires.) To secure everything, run wire cable completely thru spars on one side, mesh x2, center member, spars and mesh on other side of 'diametrically opposed spars' and out the other side. Next, tension cable so spars support mesh appropriately. Number of spar locations, cable tension, cable diameter, and even number of cables within each spar are user-adjustable variables to give the support required while minimizing mesh disturbance. You might need to use a 'needle' to thread the cable, and you might need to bend the mesh to enlarge an existing hole for the cable to pass thru, but hopefully without wholesale cutting of mesh 'fibers', reducing the possibility a fraying quite a bit. The spikes in the washers will help locate mesh even if a few fibers are cut when penetrating mesh with needle/cable.

Or just weld the damn thing.

How good are you with silver solder? It could be pretty fast and very secure to use a washer sandwich at each hole. Use silver solder to glue them together. Then drill or punch out the hole. Those holes will never fail. For that matter I think soft solder woulid be strong enough.

Denis

Would grommets made for fabric (think tarps) work?

dgfoster said:

How good are you with silver solder? It could be pretty fast and very secure to use a washer sandwich at each hole. Use silver solder to glue them together. Then drill or punch out the hole. Those holes will never fail. For that matter I think soft solder woulid be strong enough.

Denis

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Grommets do sound like a good solution, but I don't know where to get them here. I have silver solder and flux for doing bandsaw blades - I presume that black flux would do fine on stainless mesh and a zinc washer? Seems like that could be a good solution.

I've embedded stainless wire mesh ends in a bead of epoxy; but for lighter duty applications. Same idea as welding or silver soldering depending upon gauge.

A crimped termination (grommets for holes, etc.) would be more the standard practice, but likely more trouble for a one off. If there's a really worrisome area, you could make up a thin flange to capture the cutout and screw it together.

If the flux/solder works on other stuff, it’ll work on the washer and mesh. I’d keep the flame off the mesh almost entirely. Warm up the washers just as you would if the mesh weren’t there. Enough heat will spill over onto the mesh. Try some scrap a couple times to get your technique down. The wire will melt (too) easily.

Denis

I use low temperature silver/tin solder for this application. You will need to use muriatic acid based
flux to get the solder to flow, be sure to wash the final product with lots of water.

95/5 tin/silver solder can be applied with a regular soldering iron.

As dgfoster said, try to keep the flame away from the relatively thin mesh. In my opinion not so much to keep it from melting but more to keep the SS from oxidizing or whatever it does when it gets too hot. I have silver soldered quite a bit of SS and if you overheat it, the solder will not stick. I'm not sure if it is in fact an oxidation issue but something very squirrely happens to the SS and nothing will stick to it unless you grind it down and start over.

crossthread said:

As dgfoster said, try to keep the flame away from the relatively thin mesh. In my opinion not so much to keep it from melting but more to keep the SS from oxidizing or whatever it does when it gets too hot. I have silver soldered quite a bit of SS and if you overheat it, the solder will not stick. I'm not sure if it is in fact an oxidation issue but something very squirrely happens to the SS and nothing will stick to it unless you grind it down and start over.

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I don’t think that overheating issue is limited to stainless. I’ve done it to just about everything—-certainly lots of alloy steels, copper, bronze,etc. I (perhaps incorrectly) attributed it to burning away the flux. Once the surface is oxidized no amount of additional flux will allow flow of solder. As you said, clean back to bright metal and don’t be so ham-fisted next time! ;-)

Denis

Two thin washers with a dab of epoxy then bolt together and remove the bolts when cured. Just tighten the bolts enough to squeeze the washers flat. Or just epoxy on assembly, . I like the silver solder idea also.

As I recall from what the OP wrote earlier, this application is for pre-filtering what ultimately becomes drinking water. I think I would be cautious about using something like an epoxy, or any combinations of metals that might leach "heavy metals" into the water that is being extracted. Silver soldering stainless washers to stainless cloth would be my recommendation.

I have used slightly larger wire mesh and used a sharp tapered rod to poke holes for screws. This should just push the wires away without actually cutting any. Try it on some scrap as a test first.

specfab said:

As I recall from what the OP wrote earlier, this application is for pre-filtering what ultimately becomes drinking water. I think I would be cautious about using something like an epoxy, or any combinations of metals that might leach "heavy metals" into the water that is being extracted. Silver soldering stainless washers to stainless cloth would be my recommendation.

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Many silver solders contain cadmuim. Use eutectic 157 soft solder, it's silver and tin. Both are food safe.

jim rozen said:

Many silver solders contain cadmuim. Use eutectic 157 soft solder, it's silver and tin. Both are food safe.

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Most silver solders do not contain cadmium. A very few still do, but very few since there is so much "concern" regarding cadmium.. A simple check of the datasheets will specify their content. In this case, the way the item is to be used, even if by some chance he got hold of some cadmium containing silver solder, the contact with the material he is sifting in very large volumes and itself never coming in contact with the water, I think the risk would be minuscule. I guess, just to be able to answer some "concerned citizen" I would use the silver solder I have in my shop which has no cadmium and like most silver solders is considered food safe..

It is interesting to look at how real cadmium toxicity occurs. Thiis is from the National Institute of Health:
"Cigarette smoking is considered to be the most significant source of human cadmium exposure [4]. Blood and kidney Cd levels are consistently higher in smokers than nonsmokers. Inhalation due to industrial exposure can be significant in occupational settings. for example, welding or soldering, and can produce severe chemical pneumonitis [3].Cadmium exposure occurs from ingestion of contaminated food (e.g., crustaceans, organ meats, leafy vegetables, rice from certain areas of Japan and China) or water (either from old Zn/Cd sealed water pipes or industrial pollution) and can produce long-term health effects. Contamination of drugs and dietary supplements may also be a source of contamination [5]."

So the risk of using cadmium containing silver solder is to the person soldering in an industrial (not incidental like Jason's potential use) environment. In the area Jason is working other more immediate risks are monumentally greater than practically and I do mean practically zero cadmium exposure through drinking water related to silver soldering washers on the screen used to screen sawdust which is used make burnout media for ceramic filters to remove bacteria and crud from drinking water.

Denis