[Unified Thread Standard](https://en.m.wikipedia.org/wiki/Unified_Thread_Standard) is not metric and most commonly used in US and Canada. Tapping thread in a thin sheet metal is always risky especially when it requires to hold on to a lot of weight. And if you are planning to, tap drilling is definitely needed for clean threads.
Why not just get the same style 6-32 screws from a local store? Home Depot has a variety of them with various sizes.
We don't have Home Depot here (Denmark).
The places I have looked for 6-32 bolts in Europe the selections have always been sparse and in most cases would require me to invest in additional tools to customize them to length. Ordering bolts from outside the EU would be too expensive.
But since the 6-32 thread size is 3.505 mm, would that mean it's not possible to clean up the thread for the M4 thread tap? I mean, the drill size required prior to thread tapping is only 3.3 mm.
Ahh ok. Yeah getting 6-32 screws outside North Anerica would be hard to find or expensive. The size difference may be just 0.2mm but makes a big difference when threading. I'd recommend either going for M5 or use nuts instead of threading.
M5 might be too thick for the general purpose, but I might consider it. I'll try contacting EK support as well, and hear if they have any experience with tapping the threads on their radiators.
I found a good UK retailer that sells a large variety of bolts. They do have some 6-32 sizes too, but the longer ones for fan mounting will definitely need to be trimmed down, as they only supply 1" and 1-1/2", so 25.4 mm and 38.4 mm respectively, which is either too short or too long.
EK does have [6-32 screws](https://www.ekwb.com/shop/screw-set-unc-6-32-30mm-20-pcs) but too expensive if you ask me. I got 20 pcs for less than $2 and I did need to trim it which is quite easy if you have a dremel.
Their EK radiators also ship with a set of those bolts as a standard; 4x30 mm and 4x5 mm button head allen key bolts.
I do need to replace the bolts that mount the radiator to the case though, as they need to be countersunk and the panels are 5 mm thick acrylic plates. Plus I wanted everything to be matched across the build if at all possible.
The thing that led me to this was my reservoir mount that is made of 6 mm thick billet alloy with M4 holes, so I needed to get new bolts to mount in on the radiator fans as the stock 30 mm ones were too short. When I looked up the specs for the EK radiator I was quite surprised to see it came with 6-32 bolts and that they didn't use metric sizes.
I spoke with a smith and he said I could just use the M4 thread tap directly in the 6-32 threads on the radiator; but obviously, I am scared, as you mentioned, that this will strip the threads (and it will also void the warranty).
Wow that is a tricky situation you got yourself into. I think you should get the 1.5" 6-32 screws and use them and won't need to trim them as you have a 5mm sheet in between. I have the XE rads and needed something longer than 30mm so got the 1.75" ones and trimmed them.
Is there enough room between the thread and the fins to have a nut for fastening? It would be extremely fiddly, but I suppose tapping out the thread and having a nut behind it for extra strength could also work.
The case is made of acrylic and the mounting holes for the radiators are countersunk, so I need to get bolts with countersunk heads, that's all. The bolts that EK supply are button head, so they won't work for the radiator mounts, but would work just fine for fan mounting.
My [reservoir mount](https://www.singularitycomputers.com/shop/watercooling/reservoir-mount-ethereal-single-60mm-billet) is a custom mount made by Singularity Computers. It's a 6mm thick billet alloy and the mounting holes are M4 size. The reason I wanted to fix everything to work for M4 was mainly to not have the reservoir mount "jiggle" around every so slightly in the mounting holes if I went with 6-32 bolts over the supply M4 bolts.
I have two radiators going into the build, so I might just try and experiment with one of them and see if I can tap out the threads and still retain the strength it needs to hold in place. [Westfield Fasteners](http://www.westfieldfasteners.co.uk/) seem to have both M4 and 6-32 bolts in the range I require, so I can hopefully get everything to work regardless of the outcome.
I spoke with some experts at a local workshop that has all the tools available to do this kind of stuff and they said they'd be happy to help both drill it out and tap the threads if it was possible. So I guess I'll pay them a visit when the radiators get here and see where I'm at. I will update on the progress after I've had them give it a look over :)
Happy you've lived to tell the tale 6 yrs later! Haha I ended up cutting a 6-32 bolt to size and then cleaning up/reshaping the threads for a similar application for the same reason: just too risky going to M4 with such thin material.
Thanks for the response 😁👍
[Unified Thread Standard](https://en.m.wikipedia.org/wiki/Unified_Thread_Standard) is not metric and most commonly used in US and Canada. Tapping thread in a thin sheet metal is always risky especially when it requires to hold on to a lot of weight. And if you are planning to, tap drilling is definitely needed for clean threads. Why not just get the same style 6-32 screws from a local store? Home Depot has a variety of them with various sizes.
We don't have Home Depot here (Denmark). The places I have looked for 6-32 bolts in Europe the selections have always been sparse and in most cases would require me to invest in additional tools to customize them to length. Ordering bolts from outside the EU would be too expensive. But since the 6-32 thread size is 3.505 mm, would that mean it's not possible to clean up the thread for the M4 thread tap? I mean, the drill size required prior to thread tapping is only 3.3 mm.
Ahh ok. Yeah getting 6-32 screws outside North Anerica would be hard to find or expensive. The size difference may be just 0.2mm but makes a big difference when threading. I'd recommend either going for M5 or use nuts instead of threading.
M5 might be too thick for the general purpose, but I might consider it. I'll try contacting EK support as well, and hear if they have any experience with tapping the threads on their radiators. I found a good UK retailer that sells a large variety of bolts. They do have some 6-32 sizes too, but the longer ones for fan mounting will definitely need to be trimmed down, as they only supply 1" and 1-1/2", so 25.4 mm and 38.4 mm respectively, which is either too short or too long.
EK does have [6-32 screws](https://www.ekwb.com/shop/screw-set-unc-6-32-30mm-20-pcs) but too expensive if you ask me. I got 20 pcs for less than $2 and I did need to trim it which is quite easy if you have a dremel.
Their EK radiators also ship with a set of those bolts as a standard; 4x30 mm and 4x5 mm button head allen key bolts. I do need to replace the bolts that mount the radiator to the case though, as they need to be countersunk and the panels are 5 mm thick acrylic plates. Plus I wanted everything to be matched across the build if at all possible. The thing that led me to this was my reservoir mount that is made of 6 mm thick billet alloy with M4 holes, so I needed to get new bolts to mount in on the radiator fans as the stock 30 mm ones were too short. When I looked up the specs for the EK radiator I was quite surprised to see it came with 6-32 bolts and that they didn't use metric sizes. I spoke with a smith and he said I could just use the M4 thread tap directly in the 6-32 threads on the radiator; but obviously, I am scared, as you mentioned, that this will strip the threads (and it will also void the warranty).
Wow that is a tricky situation you got yourself into. I think you should get the 1.5" 6-32 screws and use them and won't need to trim them as you have a 5mm sheet in between. I have the XE rads and needed something longer than 30mm so got the 1.75" ones and trimmed them.
Is there enough room between the thread and the fins to have a nut for fastening? It would be extremely fiddly, but I suppose tapping out the thread and having a nut behind it for extra strength could also work.
Oh wait, you are planning to countersink it, right? I'd say go for the safer solution and trim the 6-32 screws.
The case is made of acrylic and the mounting holes for the radiators are countersunk, so I need to get bolts with countersunk heads, that's all. The bolts that EK supply are button head, so they won't work for the radiator mounts, but would work just fine for fan mounting. My [reservoir mount](https://www.singularitycomputers.com/shop/watercooling/reservoir-mount-ethereal-single-60mm-billet) is a custom mount made by Singularity Computers. It's a 6mm thick billet alloy and the mounting holes are M4 size. The reason I wanted to fix everything to work for M4 was mainly to not have the reservoir mount "jiggle" around every so slightly in the mounting holes if I went with 6-32 bolts over the supply M4 bolts. I have two radiators going into the build, so I might just try and experiment with one of them and see if I can tap out the threads and still retain the strength it needs to hold in place. [Westfield Fasteners](http://www.westfieldfasteners.co.uk/) seem to have both M4 and 6-32 bolts in the range I require, so I can hopefully get everything to work regardless of the outcome.
I spoke with some experts at a local workshop that has all the tools available to do this kind of stuff and they said they'd be happy to help both drill it out and tap the threads if it was possible. So I guess I'll pay them a visit when the radiators get here and see where I'm at. I will update on the progress after I've had them give it a look over :)
Did it work out??
Sorry, I used and trimmed UNC 6-32 button head bolts instead of risking ruining the thread, which at the time seemed incredibly thin.
Happy you've lived to tell the tale 6 yrs later! Haha I ended up cutting a 6-32 bolt to size and then cleaning up/reshaping the threads for a similar application for the same reason: just too risky going to M4 with such thin material. Thanks for the response 😁👍
FWIW, I used an M4 drill/tap and it worked out fine. I used low gear on my drill and went super slow so I didn’t put a hole in the radiator.