Countersunk PCB holes

Do any PCB packages allow you to add countersunk holes to a PCB rather than plain ones or will I just had to do it myself?

Cheers

Ian

Have you talked to a pcb fab house that can actually do this? I'm not sure many are setup for this like you would get from a metal machine shop.

What I have seen is multilayer pcbs with different cutouts on different layers,  this could be adapted as a countersink

john12ax7 said:

Have you talked to a pcb fab house that can actually do this? I'm not sure many are setup for this like you would get from a metal machine shop.

What I have seen is multilayer pcbs with different cutouts on different layers,  this could be adapted as a countersink

Click to expand...

I have not talked about it to any fab house. I just thought of it this evening so the first place I thought of to ask was here.

I am only using double sided PCBs. Would not really want to go multilayer just for this.

Cheers

Ian

Most PCB houses will request 'special' drills be denoted on a special layer, with a note expected to define which holes are counter-sunk, along with a drawing showing the hole detail.  Countersinks are usually routed out towards the end of the process with an angled cutting bit.

Hence it's nothing special from the PCB drawing program, other than another drill that happens to be on a different layer from the other drills.  If the hole is something that you'll use often you can make it a component on the mechanical layers so that keepouts and layer restrictions will be observed, etc.

It's only money... pay enough and you can get anything...  Not cheap or easy.

JR

JohnRoberts said:

It's only money... pay enough and you can get anything...  Not cheap or easy.

JR

Click to expand...

Indeed.  Cost can sometimes go up significantly when doing non-standard process.  Have had some rather pricey boards made in the past.

But I've never done countersink,  would be good to know how much extra cost it adds.  Maybe it's a common thing these days.

I only need to do it on two holes so if it is an expensive add-on I will probably do it myself. I am using allpcb.com for prototype boards at the moment. I will contact them to see if they can do it and what it would cost.

Thanks for the replies.

Cheers

Ian

ruffrecords said:

Do any PCB packages allow you to add countersunk holes to a PCB rather than plain ones or will I just had to do it myself?

Cheers

Ian

Click to expand...

Why countersunk? Will you use it as a panel?

warpie said:

Why countersunk? Will you use it as a panel?

Click to expand...

I am not using it as a panel but the problem does involve a front panel. The original design uses a 2.5mm pan head screw to fix the PCB to a die casting that in turn attaches to the front panel. The die castings have become expensive so I have replaced them with a simple standard pre tapped blocks. However the block have a 3mm tap for the part that attaches the PCB. No problem in principle but the pan head is taller and now extends beyond the edge of the front paneland could interfere with adjacent modules. A countersunk screw will fix this.

Cheers

ian

chamfered edge in a circle?

ruffrecords said:

. No problem in principle but the pan head is taller and now extends beyond the edge of the front paneland could interfere with adjacent modules. A countersunk screw will fix this.

Click to expand...

Perhaps a button head? Lower profile than pan head, they usually take an allen driver. Sometimes used to fasten console faders to the surface, prettier than pan head screws.

https://www.amainhobbies.com/team-associated-3mm-button-head-screws-5-asc3934/p7976?gclid=EAIaIQobChMI5MKkwaOU3AIVDdvACh39AQuuEAQYAyABEgJ6gPD_BwE

Might be enough clearance for you. I'm not endorsing this expensive-ass site, but they had a good picture of the size you want.

One caveat, the head OD tends to be a bit larger than pan heads. so check clearance in that direction.

Gene

Edit: A site with better pricing, and dimensions of everything, is 12mm too long?

https://www.boltdepot.com/Product-Details.aspx?product=7221

Also, when using countersunk hole in 1.6mm thick PCB material might be problematic, because of the chamfer angle  it's either going to be an oversized hole (fragile) or a screwhead which is  not completely flush. You could glue on a strip of PCB material locally and then countsink that, that'll give you 3.2mm to work with. Might be enough.
Or use a M2.5 insert.

ruffrecords said:

Do any PCB packages allow you to add countersunk holes to a PCB rather than plain ones or will I just had to do it myself?

Cheers

Ian

Click to expand...

It's not a question of the design tool, it depends on the pcb manufacturer only if they are willing/able to do that. Not an option with the cheap chinese guys.

https://www.eurocircuits.com/chamfered-mechanical-holes-or-countersunk-holes/

ruffrecords said:

... the pan head is taller and now extends beyond the edge of the front paneland could interfere with adjacent modules. A countersunk screw will fix this.

Click to expand...

I think you want low profile head socket cap screws. At least this is what I think you would see in a professional product in this scenario.

Example:

squarewave said:

I think you want low profile head socket cap screws. At least this is what I think you would see in a professional product in this scenario.

Example:

Click to expand...

I think you are absolutely right. Farnell have no such thing but I found some here:

https://www.accu.co.uk/en/low-head-cap-screws/8724-SSCL-M3-12-A2

Head height is 2mm and I have 2.27mm available. The regular M2.5 pan head screws this would replace hVE  2.1mm head height.

Many thanks for the info. I am definitely a mechanics noob.

Cheers

Ian

ruffrecords said:

However the block have a 3mm tap for the part that attaches the PCB. No problem in principle but the pan head is taller and now extends beyond the edge of the front paneland could interfere with adjacent modules. A countersunk screw will fix this.

Click to expand...

Hi Ian

Be aware that standard M3 countersunk screw (90°) need about 2mm minimum panel thickness !

Best
Zam

I was going to suggest a low profile socket head screw also. I use those to attach the faceplate to Par Metal chassis. Mostly because I like the way they look but also because they are low profile.

A threaded stud cut to length with a lock nut would probably work too.

Gold said:

I was going to suggest a low profile socket head screw also. I use those to attach the faceplate to Par Metal chassis. Mostly because I like the way they look but also because they are low profile.

Click to expand...

I ordered a bunch. The are quite attractive looking. I normally have my front panel fixing holes countersunk so they look neat but I think these low profile screws will look just as good.

Cheers

Ian

Try http://www.ebaystores.co.uk/Bolt-Base?_trksid=p2047675.l2563& they seem to have a large selection

Martin Griffith said:

Try http://www.ebaystores.co.uk/Bolt-Base?_trksid=p2047675.l2563& they seem to have a large selection

Click to expand...

Thanks for the tip Martin.  I fund they do some  button head types that have an even lower profile than the regular ones. I ordered a bunch.

Cheers

Ian