Filling small holes in metal enclosure

[xorophone]

If in the uk...  chemical metal.   

I'm in Sweden, but it looks like it's available here too, if you're not talking about a specific brand. Do you think chemical metal is better for this application than J-B Weld?

Thanks!

[EBK]

Loctite makes really good adhesives in general, so I would bet their product is roughly equivalent, especially in this low temp application.

[J0K3RX]

JB-Weld SteelStik.. easy to work with, sets in about 3 minutes, cures in about 1 hour.. You don't really have to prep the holes surprisingly it really bonds solid to even smooth edges but, you can rough up the edges if you want with a rat tail file or something. Try to get it as flush to the surface as you can because that sh!t ain't no joke to sand! If you have a little recess or dips it's easier to add a little more after than it is to sand down a high spot by hand.

[xorophone]

JB-Weld SteelStik.. easy to work with, sets in about 3 minutes, cures in about 1 hour.. You don't really have to prep the holes surprisingly it really bonds solid to even smooth edges but, you can rough up the edges if you want with a rat tail file or something. Try to get it as flush to the surface as you can because that sh!t ain't no joke to sand! If you have a little recess or dips it's easier to add a little more after than it is to sand down a high spot by hand.

Thanks for the tip! I'll check it out!

[xorophone]

Loctite makes really good adhesives in general, so I would bet their product is roughly equivalent, especially in this low temp application.

It turned out ok with normal epoxy, but it's not really the result I was looking for. It was a bit too soft which makes me very sceptical if the paint is going to last. It was also hard to sand it in a nice way. It was very hard to make it even because it was pretty rubbery and kind of came off in small chunks. It was definitely completely dry, but it might have been partially caused by bad mixing ratio.

I still think it might work, but for this pedal I don't want to risk it and I've got some time pressure, so I think I'll just use a lid from another enclosure. It's kind of sad, I know, but I'm using the cheap chinese stuff, not real hammond enclosures, so it's not too big of a deal. I'll order some J-B Weld product/products soon for future projects and keep the lid and maybe try the different fillers on it.


Edit: Don't take this as a "lesson" to never use normal epoxy to fill holes in an enclosure. As I said, my mixing ratio might have been bad and I just don't have time to try it out more. It might work perfectly if you just do it right.

[EBK]

Definitely didn't cure properly.  Sorry that happened to you.  Result should have been like super-hard plastic.

By the way, another tip for the sanding part (for next time, in your case): I found it useful to use a sharp chisel on the fully cured epoxy to get it close to level with the box surface prior to sanding.

[xorophone]

Definitely didn't cure properly.  Sorry that happened to you.  Result should have been like super-hard plastic.

By the way, another tip for the sanding part (for next time, in your case): I found it useful to use a sharp chisel on the fully cured epoxy to get it close to level with the box surface prior to sanding.

Great tip! I'll keep that in mind for the next time. I'll check on the old lid once in a while too and see if it hardens more, but I doubt it. I didn't measure the epoxy very well. I just added 3 "blobs" of each part and measuring it correctly is of course very important if you want a good result.

I'll keep experimenting with different products and the epoxy I already have so I can use it in the future. I'll also be more careful when drilling.

You've been very helpful, Eric! Thank you!

[davent]

Didn't notice anyone mentioning this but when sanding, back the paper with a hard flat block such as a chunk of wood.

dave

[xorophone]

Didn't notice anyone mentioning this but when sanding, back the paper with a hard flat block such as a chunk of wood.

dave

Yes, that makes it a lot more even. Didn't really work this time though, because the epoxy was too soft.

Which grit on the sandpaper do you recommend by the way? I used very fine sandpaper this time and dry sanded it, but that left a lot of dust "inside" the epoxy and it was impossible to get rid of it all. But I'm guessing that won't be a problem if it cures properly.

[PRR]

JB Weld is Texas and distributes mostly to the US market.

Chemical Metal does seem to be a very similar product sold in the UK.

I like JB Weld and do think our UK friends should try some to compare to CM.

[greaser_au]

consumer 2-pack mixes like epoxies and car body fillers have a broad range of mixing ratio otherwise it would be very hard to get a good cure with anything like this - but they need to be thoroughly mixed (the 'real thing' requires accurate mixing by weight, and mixing/curing temperatures are much more stringent).

What sort of ambient temperatures are you experiencing?   During curing, if you can get it up to 50C or so it will be beneficial. 
How are you storing the epoxy and how old is it? refrigerating extends the shelf life but they do get old.

One of the nice things about JBWeld and similar is that the two parts are different colours and you can clearly see when they are well mixed, clear epoxy requires more attention.

Chemical Metal is advertised as a 'polyester' (which suggests it's more like car body filler than epoxy), but the MDS doesn't make it clear what type it is.

david

[xorophone]

consumer 2-pack mixes like epoxies and car body fillers have a broad range of mixing ratio otherwise it would be very hard to get a good cure with anything like this - but they need to be thoroughly mixed (the 'real thing' requires accurate mixing by weight, and mixing/curing temperatures are much more stringent).

What sort of ambient temperatures are you experiencing?   During curing, if you can get it up to 50C or so it will be beneficial. 
How are you storing the epoxy and how old is it? refrigerating extends the shelf life but they do get old.

One of the nice things about JBWeld and similar is that the two parts are different colours and you can clearly see when they are well mixed, clear epoxy requires more attention.

Chemical Metal is advertised as a 'polyester' (which suggests it's more like car body filler than epoxy), but the MDS doesn't make it clear what type it is.

david

50°C? Woops! I did it in room temperature (about 20°C) and that's where I'm storing it too. I've only had it for a few weeks so I don't think it's old.

[greaser_au]

50°C? Woops! I did it in room temperature (about 20°C) and that's where I'm storing it too. I've only had it for a few weeks so I don't think it's old.

Don't panic, It should cure ok at around 20°C (too much below that might not do very well), but it could take a while. Warming it up just a little bit (not so it's too hot to handle!) will speed up proper curing, especially for smaller amounts.  One old trick when I was repairing PCBs was if one of the low-bake ovens (60°C) wasn't available, was to put the repair on a desk, and pull the (incandescent) desk light down over the repair  - basically putting it almost inside the lampshade... not so useful in these days of CFLs and LEDs.

In any event, It might be worthwhile 'wasting' a little bit more (just make another small mix and leave it to cure) to make sure it's ok.  Another comment I would make from experience, and this applies to any of the catalysed materials we've discussed on this thread, is that it is a LOT harder to estimate/balance the quantities correctly when making a very small mix.

Caution: *do not* heat and concentrate a larger mix of epoxy (say, 25cc (1 fl.oz.-ish) or more in a small cup) as the reaction is exothermic, and if made too warm the reaction heats itself quickly. It can get so hot it overcures itself, melts the cup it is in, and is a major risk of serious personal injury (true story about embarrasingly stupid behaviour gaining experience with the material deleted here...  ).

david

[Gentle Jack Jones]

Not sure how well it would take paint, but I've found a reasonably-aesthetic and quick-and-easy way to fill misplaced holes is with sugru, e.g., http://amzn.to/2kOqxTW.

[EBK]

Caution: *do not* heat and concentrate a larger mix of epoxy (say, 25cc (1 fl.oz.-ish) or more in a small cup) as the reaction is exothermic, and if made too warm the reaction heats itself quickly. It can get so hot it overcures itself, melts the cup it is in, and is a major risk of serious personal injury (true story about embarrasingly stupid behaviour gaining experience with the material deleted here...  ).

david

Reminds me of the time my younger brother learned that it is not a good idea to open up a crap ton of bang snaps (pea-sized thin paper sacks of friction/pressure-sensitive-explosive-coated coarse sand) and pour the contents into great big pile in the back seat of his car.     Luckily, it's OK to laugh at that experiment.

[MrStab]

if something's gonna be covered up by dark paint, i can recommend some stuff called "Power Putty" made by Unibond. it's similar to stuff the other guys have described, but it's not metallic. cure time is a matter of minutes.

strong? well, it's held one of the pivot posts in my Ibanez in place for years, so its strength is about 6 strings a half-step down.

[askwho69]

Just used a scrap aluminum sheet and cover it as top


Sent from my iPhone using Tapatalk

[xorophone]

Just used a scrap aluminum sheet and cover it as top


Sent from my iPhone using Tapatalk

if something's gonna be covered up by dark paint, i can recommend some stuff called "Power Putty" made by Unibond. it's similar to stuff the other guys have described, but it's not metallic. cure time is a matter of minutes.

strong? well, it's held one of the pivot posts in my Ibanez in place for years, so its strength is about 6 strings a half-step down.

Not sure how well it would take paint, but I've found a reasonably-aesthetic and quick-and-easy way to fill misplaced holes is with sugru, e.g., http://amzn.to/2kOqxTW.

Thanks for the tips!

Reminds me of the time my younger brother learned that it is not a good idea to open up a crap ton of bang snaps (pea-sized thin paper sacks of friction/pressure-sensitive-explosive-coated coarse sand) and pour the contents into great big pile in the back seat of his car.     Luckily, it's OK to laugh at that experiment.

Ah, I remember extracting the contents of those when I was younger. I wanted to make a really big one out of an entire package of them. Never got it to work though. What a waste!

That also reminds me of the time my friend accidentally dropped a package worth of them in the middle of the city on the sidewalk, right in front of a bunch of people. Good times!

[xorophone]

50°C? Woops! I did it in room temperature (about 20°C) and that's where I'm storing it too. I've only had it for a few weeks so I don't think it's old.

Don't panic, It should cure ok at around 20°C (too much below that might not do very well), but it could take a while. Warming it up just a little bit (not so it's too hot to handle!) will speed up proper curing, especially for smaller amounts.  One old trick when I was repairing PCBs was if one of the low-bake ovens (60°C) wasn't available, was to put the repair on a desk, and pull the (incandescent) desk light down over the repair  - basically putting it almost inside the lampshade... not so useful in these days of CFLs and LEDs.

In any event, It might be worthwhile 'wasting' a little bit more (just make another small mix and leave it to cure) to make sure it's ok.  Another comment I would make from experience, and this applies to any of the catalysed materials we've discussed on this thread, is that it is a LOT harder to estimate/balance the quantities correctly when making a very small mix.

Caution: *do not* heat and concentrate a larger mix of epoxy (say, 25cc (1 fl.oz.-ish) or more in a small cup) as the reaction is exothermic, and if made too warm the reaction heats itself quickly. It can get so hot it overcures itself, melts the cup it is in, and is a major risk of serious personal injury (true story about embarrasingly stupid behaviour gaining experience with the material deleted here...  ).

david

Thanks for the explanation. I have a small desk light that gets incredibly hot. I should try using that!

I really have to experiment a bit more with it before I attempt to use it seriously again. Haven't used the stuff many times.

[amptramp]

If you have one hole, fill it with a photoresistive sensor and wire it in series with the LED.  When there is a lot of light, the resistance goes down and the LED gets brighter.  When it is dark, the resistance goes up and the LED gets darker.  You may need series and parallel trimming and padding resistors to get the right range.

If the hole is near a control (like the anti-rotation tab on a pot), use a skirted knob to hide the hole.