A guide to personalizing the mechanic feel of your Logitech mouse.

Why you would want to hack your mouse

Just got a hold of the shiny new Logitech MX1000 laser mouse? Not quite happy with the feel of it?

I know, it's a great mouse, but the scroll wheel is just a bit too loose. Or maybe you think it is a bit too tense? And on top of it, it weighs like a brick.

I use the wheel in first person shooter games like Counter-Strike, to do things like switch between different weapons. If the wheel is too loose it will jump more clicks than I want, causing me to select the wrong weapon for the job. Highly annoying to me.

You shouldn't have to live with a mouse that doesn't suit your needs exactly, when you can fix it yourself easily. Only problem is, this will void your warranty, but who cares about that, right?

But what about my (insert favorite brand) mouse?

I swear by the Logitech brand, when it comes to pointing devices. Sorry. :-)

This writeup is based on experiences modifying my old Logitech Cordless Wheel, Logitech Wheel Mouse Optical and Logitech MX500 mice. I have not actually seen the inside of an MX1000, and the mouse wheel must be a bit different because of the sideways motion. Still I can't imagine they have changed the basic design much, and in any case it should be a fairly simple one like the one described below.

As for other brands. I would guess that the mechanism is similar to the Logitech design, but I don't know. I have never taken one apart, so I can't guarantee that your mouse won't fail catastrophically if try this. Actually, I feel the need to say, that this goes for anyone who tries this, whether it's a Logitech mouse or not. I am not responsible if you screw up your mouse, ok? Good, now let's continue.

Disassembling your mouse

First of all, I can assure you that there is nothing inside your mouse, that will explode in your face when you disassemble it, or break into so many pieces that you won't be able to put it back together again. So go ahead and find the old Phillips screwdriver, and turn your mouse back side up and look for the one or two screws that you need to loosen to take it apart.

The screws might be glued to the socket, so it is possible that some force is required the first time you unscrew it. When you have all the screws out, turn the mouse right side up. You should now be able to gently lift the lid off. It is usually hinged at one side, so you need to wiggle it a bit for the entire lid to come off.

The mouse wheel

We are now looking at the inside of a computer mouse. Let's turn to the scroll wheel first. The wheel itself is part of a small assembly of four separate pieces. First of all there is the wheel itself. It has an axle which is inserted from the right into a hole in the second part of the wheel assembly, the base. The base again is a squarish piece of plastic, that has two rails on the front and rear, which fits into two slots that sticks out from the bottom of the mouse.

On the top of the base is a thin metal spring, which looks a bit like a paper clip. This attaches at one end into the base, and at the other end it is loaded against the inside of the wheel. The wheel has teeth on the inside, and it is when the spring jumps from one tooth to the next that you get the jerky forward and back rolling motion of the mouse wheel.

The last part of the mouse assembly is a small spring that sits on the right side of the wheel, on a small axle that sticks out from the center of the wheel. This spring is responsible for counter acting the finger pressure, when you press down on the wheel to use it as the center mouse button. The whole assembly is able to slide up and down on the rails when you apply pressure from above. When it is fully pressed down, it hits a small microswitch below the assembly, that registers the center mouse button press.

Hacking the scroll wheel

The easiest modification you can do is to simply remove the spring that prevents the wheel from turning freely. However the spring tension is fairly light to begin with, so you probably want to increase it instead of removing it.

Lift up the wheel assembly, and take it apart. Have a look at the paper clip spring. Find a real paper clip and a pair of pliers. You need to bend the paper clip into a shape that looks similar to the original spring. It doesn't have to be an exact match for the original. You will need to bend it a bit, test to see if it fits, bend it some more, repeat until you are happy with it. Put the mouse wheel assembly back together and test the tension. It will most likely need more fine tuning before it is perfect.

One thing to take note of is the lubrication of the assembly. Most likely a few of the parts is covered in some kind of white goo, which acts as a lubricant. It is fairly important that you keep the various parts lubricated when you fit the new spring. Especially the edge of the spring, that slides against the teeth of the inside of the wheel needs to be properly lubricated, or else the teeth will wear. Hopefully there is some leftover lubrication, smeared somewhere where it is not needed, that you can use if there is not enough on the part you are fitting. Otherwise you need to get some other kind of grease to lubricate with.

The weight issue

I like the weight of my MX500 actually, so I havent fiddled with it. But if you want to, you can. The MX series of mice actually has a solid square piece of metal embedded in them, just to add weight. If you want to make your mouse lighter, you can simply remove this metal weight. You can also add more, if you feel the mouse handles better that way. Remember the placement of the metal, that is whether it is put at the front or in the rear, is important to the handling.

That's it for now. Enjoy your improved and personalized Logitech mouse.