How are you guys mounting pcbs in cases.

I know on a couple of guitar pedals i've used a little plastic thing that has double sided tape on the bottom that sticks to the case and then a wing type thing that goes through the holes in the pcb.

Just wondering if there are any better ways or if anyone knows where i could source something. I suppose on projects that generate alot of heat like the pm660 this wouldnt be ideal because the glue would go soft.


Been searching, http://jaycar.com.au/productView.asp?ID=HP0760&CATID=32&form=CAT&SUBCATID=549

is that what i should use or are there better ways?

look up standoffs and or spacers at the local hardware store

Thankyou for putting a name to what i was looking for!

The stick-on mounts are good for light boards and small abuse. Try to mount a DEC-10 RAM board on four of those, it will bust the stick-on before you get the beast onto a dolly.

BIC pen or other hollow tubing. Saw to length. Use 1" (or whatever) #6 machine screws and nuts (or whatever metric fits PCB holes and BIC pens). This scales to 1/4" screws and drilled plastic pillars if you are mounting heavy-metal boards. You can buy such hardware, often less brittle than BIC pen stock.

Tracks. Put U-channels inside the case or rack, design PCBs with nothing critical on those edges, slide the cards. The first computer I was ever in (yes, "in") was racks of channels with card-connectors. You can buy little plastic boxes with card-channels.

I like wrapping PCBs in old foam and just tossing them in, but some people snear at such laziness.

Maybe a little expensive just for standoffs, but if you can swing it, get a "Nutsert" or "Rivnut" kit from most Fastener/Nut/Bolt shops. It is a threaded nut, that is like rivetted into your panel, so on one side of the panel it finishes off flush, so no protruding screw head sticking out which can be a problem with rack mount cases. The other side, the nut sits up maybe 5mm, but varies depending on the size of nut. All you do is drill the appropriate sized hole and using the nutsert tool, just squeeze/rivet the nut in.

Coventry Fasteners at Alexandria have stock, part no: AV-7486, it is $110 + GST for a kit including tool and about 30 nuts, but you can buy more nuts. You just have to check about the nut sizing coz I think this kit has the bits for 4, ,5 ,6 and 8mm, but not sure if this is the thread size or the outside nut diameter. You probably want something for 3mm size screw threads, so you may have to buy an extra adaptor or two and some nuts.

You can google for nutserts to see more. You'll find a 100 more uses for this when you have one.

Michael

Junction said:

Maybe a little expensive just for standoffs, but if you can swing it, get a "Nutsert" or "Rivnut" kit from most Fastener/Nut/Bolt shops. It is a threaded nut, that is like rivetted into your panel, so on one side of the panel it finishes off flush, so no protruding screw head sticking out which can be a problem with rack mount cases. The other side, the nut sits up maybe 5mm, but varies depending on the size of nut. All you do is drill the appropriate sized hole and using the nutsert tool, just squeeze/rivet the nut in.

Click to expand...

You can do that, but be aware that you're loading the nut from the wrong side. Rivnuts are designed be loaded ("pulled") at the end that is flush with the panel. If you load it from the other side, you'll slowly pull it loose (decompress it). Probably not an issue for something as light as a PCB with no transformers, definitely an issue for toroids or other heavy objects.

JDB.
[of course, this is only an issue if you move stuff around. Then again, if it's never moved you might as well use double sided tape and be done with it*]

* the fine print: that is a joke. Don't ever rely on something as feeble as double sided tape to hold things in place in mans-powered equipment! Everyone knows you should use tie wraps and duct tape. Haven't you guys watched MacGyver? Seriously: this stuff'll kill you and/or set your property on fire if you're not careful.

Generally the double sided tape application is a poor practice whether it is a light or heavy board or in high temperature environment. However, there is a particular  industrial/permanent type of double sided tape which once bonds almost impossible to seperate. You literally have to crow-bar it to remove. It is also rated in all sorts of temperature conditions, high or low. I have been using it to bond plastic to plastic, plastic to metal and metal to metal.

However, I hate those locking type stand-offs. They are fast on assembly but pain in the butt for servicing the board. If you do not specifically want ground contact between the board and the chassis use plastic threaded stand-offs.

I use metal standoffs screws and nuts from Rat Shack.

Erm . . .


  I've been using bluetack!



      Sssssh! Don't tell . . . .



          Someone

in holland i buy everything i need from skiffy.com costs about 10-15 euro for 500 stand-offs and about 10 euro for a 1000 screws.

So most people are drilling holes in the case and then screwing in spacers yeah?

Sahib, any hints as to where to look for that industrial strength tape? I'd prefer not to have screws protruding if i can avoid it. Though i suppose that is innevitable whenever you mount a toroidal in a case.

Hey Guitarist,

I'm also thinking of ways to do this - the point being that i dont' want screws potruding underneath the case as it will scratch whatever i place it on.

On my rack cases (purushas ones) the front panel has about 1-2mm overhang from bottom panel - i will place small rubber strips or feet for protection.

I was thinking of lining the case with 5-7mm plywood and screwing it from the sides of the case,

then screwing the pcbs into it.

This might be from the top down - or by pre fastening the screws from the bottom.

Other idea is to look into flush mounted screws - would be good to sort this,

the torrodial bolt is not a problem on a 2ru (mount on the side of case) but i've been wondering about a 1ru im making (nite eq)

might make a bracket for the transformer that bolts to the side..... but that might be too much effort

the torrodial bolt is not a problem on a 2ru (mount on the side of case) but i've been wondering about a 1ru im making (nite eq)

Click to expand...

I'm in the process of solving this very problem with my Night EQ build. Solution: PCB mounted torroidal (like this for instance: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TE70053-ND).

I'm using short stick-ons that I got from Small bear and and a PCB blank from Radio Shack. I'm not too worried about using stick-ons, the tranny isn't really that heavy and with 4 posts I'd have to give it a pretty good shake to get them lose. I'll follow with pics as soon as I can get some spare time to follow through...

TheGuitarist said:

So most people are drilling holes in the case and then screwing in spacers yeah?

Sahib, any hints as to where to look for that industrial strength tape? I'd prefer not to have screws protruding if i can avoid it. Though i suppose that is innevitable whenever you mount a toroidal in a case.

Click to expand...

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=retrieveTfg&Ne=4294958713&Nr=AND%28avl%3auk%2csearchDiscon_uk%3aN%29&N=4294962344+4294955596+4294734303&Ns=stockPolicy_uk%7c1%7c%7cnew_uk%7c1&binCount=102&multiselectParam=4294962344%204294955596&selectAttribute=Double%20Sided#breadCrumb


The other option would be to use two pack epoxy. You can even get one which is metal powder based and cures as a lump of metal. You first mount the stand-offs onto the board, then apply the epoxy onto stand-offs and place the board inside the case. I have used those in the control panel of an industrial dishwasher that I did control electronics for.

But the truth is, why are you against drilling holes? I would not only drill, but if the thickness of the material permitted I would even countersink them.

Hello,
PRR wrote :  " I like wrapping PCBs in old foam and just tossing them in, but some people snear at such laziness. "
I did it too many times, for small pcb's, ( like DI box ) and I like it.
Easy, fast and efficient solution 
Guy

I'm not against drilling as such, i'd just prefer not to if i can, mostly because of the protruding screws, but i suppose its case dependent.

Has anyone used liquid metal glue (metal super glue) Its looking like drilling is the best method, just trying to find out all the other options first.

what's wrong with hotglue?

how about this:

http://www.smallbearelec.com/Categories.bok?category=Enclosures&searchpath=517045&start=41&total=41

would this be adequate in gluing (welding) metal standoffs to the bottom of a case?

JB weld is great for this, maybe overkill. I just drill and use standoffs and some 4-40 screws and bolts.

I used some double-sided "permanent" tape from Jo-Ann Fabrics (u.s.) to mount some input transformers to a PCB: so far so good.  I suspect that the permanent nature of the tape would go out the window for heavier objects or higher temp. environments, but for this application, its a charm.  Nicer than drilling the PCB, too.  Seems like the general consensus is : whatever floats your boat.