[MrMajestic2]

Har anyone tried gluing standoffs to the bottom of the case instead of drilling. I find drilling to be a pain in the behind and its hard to get it right with only a handheld drill. I was thinking some kind of epoxy would work well for this, what do you think?

 

[luvdunhill]

Quote:

Originally Posted by MrMajestic2 /img/forum/go_quote.gif Har anyone tried gluing standoffs to the bottom of the case instead of drilling. I find drilling to be a pain in the behind and its hard to get it right with only a handheld drill. I was thinking some kind of epoxy would work well for this, what do you think?

well, Eagle Plastic Devices sells things that might work out better, look at their PCB accessories at Mouser.

Another option, is to attach standoffs to the PCB and then use white acryllic paint and cover the end of the standoff that will be affixed to the case. Then, press down, lift off, and voila, perfect guides. Drill, clean the paint off, then fasten.

 

[n_maher]

My opinion, it's a terrible, horrible idea. I've repaired amps in the past that have tried to use glue only to have the standoffs break off the chassis and result in damage. It's not that hard to drill a hole in the right place, either just use the board itself to mark the holes or if you're worried about the board shorting to the case (if you've been testing and haven't bled the caps) make a template of the pcb using paper. Also, there's nothing to say you can't drill the holes 1 size larger than required and give yourself a little play.

Just don't glue them, please.

 

[MrMajestic2]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif My opinion, it's a terrible, horrible idea. I've repaired amps in the past that have tried to use glue only to have the standoffs break off the chassis and result in damage. It's not that hard to drill a hole in the right place, either just use the board itself to mark the holes or if you're worried about the board shorting to the case (if you've been testing and haven't bled the caps) make a template of the pcb using paper. Also, there's nothing to say you can't drill the holes 1 size larger than required and give yourself a little play. Just don't glue them, please.

Just to spite you, I will glue them

Seriously, I was kind of concerned with them breaking off like you say. It was just an idea that needed some input, thank you guys.

 

[error401]

Quote:

Originally Posted by MrMajestic2 /img/forum/go_quote.gif Har anyone tried gluing standoffs to the bottom of the case instead of drilling. I find drilling to be a pain in the behind and its hard to get it right with only a handheld drill. I was thinking some kind of epoxy would work well for this, what do you think?

I can recommend against using superglue, at least. I tried that for a project and had trouble getting it to bond to the aluminium case, even after sanding it down a bit at the contact area. On top of that, it was somewhat difficult to get the standoffs to stay in the right place while the glue sets, so once it set and they were slightly off, the force of the screws trying to pull it into place would break it off from the case.

Not recommended...

 

[JackH]

Quote:

Originally Posted by MrMajestic2 /img/forum/go_quote.gif Har anyone tried gluing standoffs to the bottom of the case instead of drilling.

I recommend this technique, but only for plastic cases and standoffs. I like to use threaded nylon standoffs and nylon screws, also. You have to be sure to choose a glue that's compatible with the plastics involved. The super-glue type of stuff usually works well. Get one that comes in a bottle with a brush applicator if possible.

Positioning is quite simple. Attach the standoffs to the PCB, then brush a small amount of glue on the bottom of the standoff. It doesn't take much. Carefully place the PCB in the case, but don't press down on it... the glue will not take hold until you do. Once the board is in place, press down on each screw for a few seconds, and you're all set. I like to back the screws out right after pressing the standoffs in place, just to make sure they're not accidentally glued in place. They can be re-installed an a few minutes.

This method works quite well for lightweight things like PCBs and terminal blocks, but I prefer to drill and use a metal bolt for fastening heavier items, like transformers.

 

[Uncle Erik]

Glue usually weakens when heated and there's plenty of heat inside an amplifier's case. It will weaken over time and something might short against the case when a support gives way or slides into something else.

And I hear 'ya. Drilling holes is a total pain in the back end, not to mention getting them centered and using chassis punches by hand. That eats up 50% of the time I spend on a project.

 

[nikongod]

i spend more time drilling than soldering for most projects, and i have a drill press!

i think it was nate who once said that case word is at least 50% of the project. i totally agree.

 

[holland]

Sand off anodizing and use epoxy for cold weld purposes, it'll be fine. Look at some automotive products or marine products. Permatex cold weld or JB Weld.

Clean the surfaces with acetone after sanding.

Don't just plop the standoff on it and walk away. Put the PCB with stands or mock up a PCB size with the holes there. Prep joining surfaces with sanding and acetone, bolt the standoffs on, apply the JB Weld, place, let it cure for a day, unbolt and the standoffs will remain in place.

Drilling is quicker with instant gratification.

 

[amb]

Glue will not have the same level of mechanical integrity as screws. Some PCBs can be fairly heavy with all parts mounted. Vibration or movement of the chassis could easily break the board(s) loose. If this happens and the power is turned on, short circuits could occur and cause damage.

 

[Uncle Erik]

Forgot to mention one toy that made drilling a bit easier, the auto-centering punch:

Here's one on Amazon:

Amazon.com: Auto.Center Punch Brass 6"X5/8": Home Improvement

I got mine at Home Depot for about $10, and it's worth every cent. I use that with a square to lay out my chassis and then scribe an X at each point with an awl before hitting it with the punch. Then I'll use a thin drill bit to make a pilot hole before drilling a bigger one. It takes a little longer, but this lets you get the holes precisely where you want them. A little sandpaper and a file will make them look professional, too.

 

[MASantos]

Another vote for not gluing the standoffs to the case. Use a center punch to mark the holes. Then secure the bottom of the case to a thick piece of wood and drill carefully using the correct drill. A good quality drill makes all the diference, don't use an el cheapo drill as it will only make your life more dificult.

 

[balrog]

Use a layout dye ,like Dykem. Sometimes even a Sharpie marker will work. +1 on using a centerpunch.

Make sure to use a sharp drill bit. Maybe a split point bit will help you to keep it from walking when you are starting the hole.

Get a set of calipers, square and a steel rule to help you with layout.

If you can find a set of transfer punches, that may be the easiest to use. Something like this:

Harbor Freight Tools - Quality Tools at the Lowest Prices

 

[keyid]

if you must glue punch a hole in case w/ small nail & hammer multiple holes better. Make sure epoxy goes into the hole to other side. Wipe dry it should hold pretty well. You can sand the excess.

 

[n_maher]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif i think it was nate who once said that case word is at least 50% of the project. i totally agree.

Yup, getting the pcb stuffed is half the battle, if you're lucky. I suppose if you don't care about the end result you can slam something together pretty quickly but I wouldn't.