micro Servo 9g Screw Size. What Screws Are Used To Install The Servo?

Have you ever encountered this situation: you bought the microservo9gservowith great joy and prepared to install it on your robot or model aircraft, but you ended up staring blankly at those small holes - what size screws should you use? If you choose a screw that is too small, it cannot be tightened, and if you choose a screw that is too large, it will directly damage theservo. This is indeed a pitfall that every novice who plays the servo will step into. Today, as an old player, I will talk to you about the screw dimensions of the 9g servo, ensuring that you can choose the right screws and install them smoothly after reading this.

What is the size of the 9g servo screw?

The most common screw specifications for micro servo 9g are M2 and M2.5. M stands for metric thread, and the number is the diameter of the thread in millimeters. Most 9g servos, such as the popular SG90, have mounting holes designed for M2 or M2.5. You can take out the servo and take a look. If the hole looks thin, it is most likely M2; if it is slightly thicker, it is M2.5. If you are not sure, find a ruler and measure the hole diameter. About 2mm is M2, and about 2.5mm is M2.5.

I would like to remind you here, never use self-tapping screws to screw in, otherwise the plastic mounting ears of the servo will be cracked. Be sure to use machine thread screws, the ones with uniform threads. The length of the screw generally needs to be 4mm to 8mm, depending on the thickness of the material you are fixing. If it's too long, it will hit the inside of the servo, and if it's too short, it won't bear the force.

Are the 9g servo screws of different brands universal?

This is a good question. The answer is that most of them are universal, but there are a few that are not universal. For mainstream servos such as Tower Pro's SG90 and MG90S, and EMAX's ES08A, the screw holes are basically opened according to M2 or M2.5 standards. As long as you know which specifications of the servo you have, you can basically use most brands.

However, some special brands or metal-cased servos may use slightly different specifications. For example, some all-metal digital servos use imperial threads, so metric screws cannot be used. The safe approach is to look at the product details page or the packaging box when buying a servo. The recommended screw specifications are usually marked on it. If you really can’t find it, just ask the seller’s customer service and they will tell you.

How to choose the length of 9g servo screw

There is a tip for choosing the length. You first measure the depth of the servo mounting hole, plus the thickness of the material you want to fix. The two add up to the total length that the screw needs to be screwed in. But please note that when screwing in the screw, do not push it to the bottom, leaving 1-2mm margin. For example, if the installation hole is 5mm deep and you want to fix it on a 3mm thick plastic plate, the total length will be 8mm. Just choose a 6-7mm long screw.

To give you a reference value, in most cases it is enough to choose 6mm long M2 or M2.5 screws. If you are fixing it on a thicker material, such as a carbon fiber plate above 5mm, you may need 8mm or even 10mm. Remember one principle: it’s better to be short than long. If it's too long, it'll be troublesome if it breaks the servo gear. If it's shorter, it won't be as strong at best. Just change it to a longer one.

Pay attention to the specifications of the 9g steering gear and steering arm screws

The screw holes on the small plastic arm that comes with the servo are two different things from the mounting holes of the servo itself. The screws on the rudder arm that fix the connecting rod or the rudder arm itself are usually thinner M1.7 or M2. Many novices confuse this point and try to fix the servo with the screw on the rudder arm, only to find that it is too thick to screw in.

The fixing screw in the center of the steering arm is the one locked on the output shaft of the steering gear. It is usually M2 or M1.7, and it is very short, only about 3-4mm. Be careful when disassembling the rudder arm, as this screw is particularly easy to slip or get lost. It is recommended that you prepare a small Phillips screwdriver for easier operation.

Which material is better for 9g servo screws?

The screws used for 9g servos on the market mainly include nickel-plated iron and stainless steel. Nickel-plated iron is cheap, but it is easy to rust after being used for a long time, especially if you play with ship models or often use it in a humid environment, rust will soon appear. Stainless steel is a little more expensive, but its rust resistance is much stronger, its strength is better, and it is not easy to twist.

I recommend you just buy the stainless steel one. It only costs a few dollars more, but it saves you a lot of worry. 304 stainless steel is relatively common and sufficient. If the place where you are installing has a large vibration, such as on a drone or a car, it is best to use screws with anti-loosening glue, or use a little screw glue during installation to prevent the screws from loosening while flying.

Where is the most reliable place to buy 9g servo screws?

It is almost impossible to buy such small screws in hardware stores. The smallest they have is M3. Online shopping is the most convenient. Just search "M2 screw 6mm" or "9g servo screw set" on a certain website and you will find a lot of them. Many model shops have specially prepared 9g servo screw packages, which are available in various lengths and only cost a few yuan to post. It is recommended to buy this kind of package directly to avoid having to replenish the stock again and again.

When buying, pay attention to distinguish between cross and hexagonal head shapes. The cross-shaped one can be screwed with an ordinary screwdriver and is easy to operate; the hexagonal one requires an inner hex wrench, but it is not easy to twist. I personally prefer the inner hexagonal ones because they are more durable and can have greater torque. It is recommended to buy from shops that specialize in model making. They know the specifications of servos better and will not send the wrong goods.

Have you ever damaged a servo because you chose the wrong screw? Come to the comment area to talk about your pitfall experience, so that more novices can learn from it. If you think this article is helpful to you, don’t forget to like and share it with your model friends!