How to Build Your Own Cross Drilled Copper Waterblock

If you’ve ever looked at most water blocks on the market and thought to yourself “Heck, I can make one of those”, you weren’t far off. Water-cooling, being an extremely niche market, almost all designs currently being manufactured are fairly simple and require no specialized tooling to keep production costs low.


Many people, in one way or another, have access to some basic wood and metal working equipment. As you’ll find out in this article, making your own water block isn’t something that requires an engineering degree or lots of experience working with metal. Aside from being economical, it’s also a lot more fulfilling to make something yourself instead of buying something that was made in the exact same manner by someone else.

When designing the water block, I opted for a cross-drilled type (shown above) because it entailed the least amount of discrete steps (4 identical holes to drill and tap) to build, and I only needed one piece of copper to make it. This was going to be my first water block – and water cooling system for that matter – so I played it safe by using the most fool proof design possible.


A TidalPool type design would most certainly yield higher performance. If you don’t mind some extra steps then that might be a better idea for you.

I made this block using the most standard stuff I could find, but there are specific drill bits for Copper drilling of deep holes and things of the like, which if you know enough about them, can make the job a lot easier. To make this article as relevant as possible to as many people as possible, I will limit the discussion to regular old wood/steel working tooling.

To make your own cross drilled water block you will need the following:


  • Drill Press
  • Belt Sanding Station
  • 11/32″ Wood/Steel Drill Bit
  • 11/32″ Plumber’s Thread Die
  • Two-Way Adjustable Vice for Drill Press
  • Bench Mounted Vice
  • Four Clamps
  • WD-40


  • One 2″x2″x0.5″ copper block (~$3.50 at local or online metal supplier)
  • Two 1/8″ plugs (~$0.50 at local hardware store)
  • Two 3/8″-1/8″ fittings, straight or bent ($1.50 – $3.00 at local hardware store or plumbing supplier)
  • Epoxy (~$3.00 at local hardware store)

Before I start, I’d like to take a moment to talk about shop safety: Make sure you read and understand the safety rules that come with your power tools. Knowing how to use your power tools will greatly reduce the chance of injury. Also, always wear safety glasses.

That said, let’s get started:

1- Square the block at the belt sanding station to ensure better drilling/tapping alignment. Have a container filled with water handy to throw your block in periodically as it’ll get extremely hot while being sanded. Avoid wearing metal working gloves or anything of the sort, as the sander can easily suck them in and cause serious injury.

2- Mark the holes to help center the drill bit. You can do this by either drawing guide lines on the block or printing out your blue prints to scale and fastening them to the block, and then marking the exact center through the paper.

DO NOT drill pilot holes!

That’s what I did on my first copper block and I found severe bulging on the outer walls of the block. I had to scrap that piece anyway because of other reasons, but the pilot holes didn’t help at all using regular wood/steel working bits.

3- Set up the vice and drill press properly to help everything else go smoothly.

  • A/ Use two pieces of scrap wood to put between the vice and your metal block to prevent damage to the block.
  • B/ Center the vice under the drill-head and clamp it down.
  • C/ Adjust the height of the drill press’ base so the bit doesn’t have to travel more than a couple of inches to reach your block.
  • D/ Lock the drill’s maximum vertical stroke in relation to your block. This will make it easier to know when you’re done with the hole and it prevents you from drilling all the way through by mistake.
  • E/ Center the drill bit onto the mark you made previously by turning on the drill, bringing it down just above the block, and adjusting the position of the block in relation to the bit’s spinning tip by turning the vice’s adjustment widgets.

  • F/ Don’t set your drill speed too low, or it will bind more often in the block and not expel the metal shavings out, forcing you to periodically use compressed air to do this yourself.

Drill Press

4- Plunge the drill bit into the block slowly but firmly. Don’t go too fast or you’ll end up with a misshapen or too big hole. Unless you’re using a bit with a flat top rake, or with nicks in the cutting edge to break up any long spiral turnings, you’ll need to remove the bit from the hole as soon as you see these spiral turnings winding up the bit. This will keep binding to a minimum.

Make it a habit of squirting some lubricant into the hole while you’re drilling. I recommend good old WD-40, as Teflon boiled away too quickly and cutting oil didn’t perform as well on copper as it did with aluminum for me.

Once the first two holes are completed, unscrew the block from the vice and flip the block over onto its side to cross drill. Repeat step 3 to set your equipment up for a second round of drilling.

The trickiest part of the whole operation is dealing with the moment when your drill bit crosses from solid metal to the empty space created by your previous holes. You will have to pay very close attention to when you’re nearing these transition points, as the bit WILL bind at those moments. It’s frightening the first time it happens, but if your rig is very securely fastened to the drill press your block won’t suffer any damage.

When it binds, simply turn the drill press off, and turn the chuck (the thing the bit is held by) counter clock-wise to loosen it from the block. If you see that something has shifted position from the jolt of binding, you will have to re-center the block as best you can. To punch through the transition area, go excruciatingly slowly, hardly applying any pressure.

5- Tap the holes using the proper sized die with a plumber’s threading. Place the block in a standard bench mounted vice between two scrap pieces of wood to protect it. Use a level to make sure it’s not sitting crooked.

To tap the holes you will have to apply a firm and even pressure on the die while turning it slowly into the hole, while keeping the die as vertically aligned with the hole as is humanly possible. This takes a little practice to get just right, so you may want to use a scrap piece of copper with a couple of test holes in it to mess around with first.

When the task of getting the die “hooked-up” in the hole and threading in straight is accomplished, you simply have to keep turning the die clockwise 1/8 of a turn to cut the thread, and then counterclockwise ½ of a turn to clear the shavings, repeating until the thread goes down deep enough for your brass fittings to screw in all the way, while unscrewing the die periodically to clean out the die and block. Lubricant also helps in the tapping process, so don’t skimp on the WD-40.


6- Lap your block on the belt sander once the drilling and tapping is complete. Even if you didn’t drill pilot holes you will find that there is still a little bulging present on the block’s faces that you will have to get rid of.

Then you can move on to progressively finer grits of wet/dry sandpaper to give your block an ultra smooth finish (lapping). If you have a buffer and Copper-buffing compound, you can also give your block a mirror finish to impress the ladies.

7- Screw your fittings and plugs into the block. Copper being as soft as it is, it’s inevitable that they will screw in with the tiniest amount of play. This may seem unsettling at first, but it turns out for the best, as this gives you just enough room to add some epoxy onto the threads with a toothpick and then screw the fittings and plugs in permanently.

Put a little epoxy ring around the outside of your brass hardware where they meet the copper block to make an airtight seal and they will be as good as welded in place.

Expect your first copper water block to require between one and two hours of shop time. You can download blueprints for the crossed drilled water block I designed and built HERE.

All these steps apply to aluminum also, but when a copper block of the required size costs $3.50, I really have no idea why anyone would want to use aluminum, as 6061-T6 is a much poorer heat conductor than 0.999 pure copper is.

If you know of ways, tools, etc… to either speed up the process of making a water block or make it more precise/easy/safe please feel free to share them with me.

Good luck with all of your water cooling projects!

Philippe Bartoszewicz

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