[ruffrecords]

I just purchased  a 3U version of a Modushop Dissipante case to enclose a chunky power supply for the Mark 3 tube mixer. I chose it because its sides are big heat sinks which I intend to use to mount a TO220 FET regulator for the HT supply. Surprisingly (for me) I found the assembly pretty straightforward. However there seems to be absolutely no provision for mounting anything on the heat sinks which seems a bit of an oversight to me. I checked their web site but I can find no information about this. I am very reluctant to drill and tap holes but unless I have missed something obvious ( a definite possibility) it looks like this may be the only way.

Anyone had experience with these?

Cheers

Ian

[squarewave]

Just clicking around I found this:

  https://diyaudiostore.com/pages/universal-mounting-specification

Looks like maybe it's only for their "DELUXE" chassis though.

[ruffrecords]

Just clicking around I found this:

  https://diyaudiostore.com/pages/universal-mounting-specification

Looks like maybe it's only for their "DELUXE" chassis though.

Looks like these are a different company based in the USA. Looks like they import the Dissipante from Italy which is where I get them:

https://modushop.biz/site/index.php?route=common/home

Maybe the US company adds the tapped holes to the heat sinks. I can find no mention of it on the Italian site.

Cheers

Ian

[kosi]

Try to contact modushop, they respond pretty fast !

[zamproject]

Hello

It seem normal to me that there is no pre drill, so the DIYer/manufacturer can layout as requested
I know you are not fan of mechanics...
You don't necessary need a thread if you don't have the tool, just drill at M3.2 or 3.5 between dissipator wings and use screw/nut

Best
Zam

[JohnRoberts]

If it's aluminum (and thick enough) you can use thread cutting screws. If not thick, machine screws and nuts should work.

JR 

[ruffrecords]

Drilling between the fins seems a good idea. I will try that. I am not a fan of self tapping screws, especially the ones used in sheet steel but if there are ones designed for a fairly deep hole in aluminium then I'll give them a go.

Cheers

Ian

[JohnRoberts]

Drilling between the fins seems a good idea. I will try that. I am not a fan of self tapping screws, especially the ones used in sheet steel but if there are ones designed for a fairly deep hole in aluminium then I'll give them a go.

Cheers

Ian

Sheet metal screws are a different animal but can work with thin metal. I've had some success with thread cutting screws in aluminum extrusions but mostly screwing into extruded bosses so plenty of meat to grab into.

Machine screws and nuts are certainly more straight forward, and OK if you are not trying to engineer out every last drop of hand assembly labor.

JR

[ruffrecords]

Sheet metal screws are a different animal but can work with thin metal. I've had some success with thread cutting screws in aluminum extrusions but mostly screwing into extruded bosses so plenty of meat to grab into.

Machine screws and nuts are certainly more straight forward, and OK if you are not trying to engineer out every last drop of hand assembly labor.

JR

So, what do I search for if I want self threading screws rather than sheet metal self tappers? Is it this kind of thing:

https://uk.farnell.com/tr-fastenings/m38-prstttz100/screw-pozi-pan-steel-bzp-m3x8/dp/1420122

Cheers

Ian

[JohnRoberts]

So, what do I search for if I want self threading screws rather than sheet metal self tappers? Is it this kind of thing:

https://uk.farnell.com/tr-fastenings/m38-prstttz100/screw-pozi-pan-steel-bzp-m3x8/dp/1420122

Cheers

Ian

My goto source for small quantity hardware is Mcmaster carr... not cheap but they have a good selection.

https://www.mcmaster.com/screws

They list 4 different kinds of tapping screws for metal
https://www.mcmaster.com/screws/=772a4ab440934d9c87d020f7d900c4cbk3xhyn9p
https://www.mcmaster.com/screws/=772a4ab440934d9c87d020f7d900c4cbk3xhzd86
https://www.mcmaster.com/screws/=772a4ab440934d9c87d020f7d900c4cbk3xhzus7
https://www.mcmaster.com/screws/=772a4ab440934d9c87d020f7d900c4cbk3xi0j8v

Thread cutting screws put less stress on the metal, while thread forming screws are tighter. I suspect one is better if you anticipate taking things apart and reassembling them later.

How thick is the metal you are working with...?  Sheet metal is not my area of expertise (among the many I am not expert in).  Machine screws and nuts seem harder to screw up.

JR

[ruffrecords]

How thick is the metal you are working with...?  Sheet metal is not my area of expertise (among the many I am not expert in).  Machine screws and nuts seem harder to screw up.

JR

it is an aluminium heat sink. The main 'meat is about 5/16 inch thick.

Cheers

Ian

[ruffrecords]

I just found a 3mm drill long enough to fit between the fins. I just successfully drilled a 3mm hole. Looks like this is probably the standard way to do it.

Thanks for everyone's help.

Cheers

Ian

[ppa]

I just purchased  a 3U version of a Modushop Dissipante case to enclose a chunky power supply for the Mark 3 tube mixer. I chose it because its sides are big heat sinks which I intend to use to mount a TO220 FET regulator for the HT supply. Surprisingly (for me) I found the assembly pretty straightforward. However there seems to be absolutely no provision for mounting anything on the heat sinks which seems a bit of an oversight to me. I checked their web site but I can find no information about this. I am very reluctant to drill and tap holes but unless I have missed something obvious ( a definite possibility) it looks like this may be the only way.

Anyone had experience with these?

Cheers

Ian

I used them for hifi power amps that I designed. The quality of a "pesante dissipante" is very high.
I know Hi-Fi 2000 from more than 25 years and never I have had problems with them.
BTW I am just using a 3U pesante dissipante chassis kit.

Pier Paolo 

[rackmonkey]

I just found a 3mm drill long enough to fit between the fins. I just successfully drilled a 3mm hole. Looks like this is probably the standard way to do it.

I’d recommend to anyone on this forum to invest in a few single aircraft drill bits in frequently used sizes, or in a small set.  Grizzly in the US ships worldwide and this set is a deal at $13 and change:

https://www.grizzly.com/products/Grizzly-Aircraft-Extension-Drill-13-pc-Set-1-16-1-4-x-6-Long/G9750

Aircraft bits run about 6 inches long, right down to the smallest gauges. Compare to your average jobber bit at 3 inches. You have to be a little more careful with the smaller gauge ones, but there’s no substitute when you really need it.

Metric available at McMaster Carr, MSC Direct and the other usual industrial sources.

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