Posted by on 3/1/2021
Though we carry more micro-linear motion products than anybody, there are times when our customers have a stroke-length requirement that can't be met with an off the shelf product. While some larger actuators come with adjustable end limit switches, this isn't practical on micro actuators.
There are however, several ways to adjust the stroke of your micro actuator.
There are however, several ways to adjust the stroke of your micro actuator.
The ability to adjust the stroke of an electric linear actuator for greater precision is incredibly useful. There are hundreds of applications that might require a custom stroke including:
- Micro robotics applications
- Opening and closing drawers and cupboards for home automation
- Animatronic displays
- Industrial or medical applications with tight tolerances
- Automotive customizations
- RC applications such as air brakes, landing gear, flaps or retractable canopies
There are some linear actuators with adjustable end-limit switches, most are non-adjustable. I'm going to walk through what you can do to get the custom stroke linear actuator that you need.
There are three ways to adjust the stroke of a linear actuator.
- Adjust the actuator's extension and retraction
- Adjust only the retraction
- Adjust only the extension.
Before you get started with a custom linear motion system, consider whether it might be easier to modify your project.
Sometimes simply adjusting a mounting point could net you the same result as any of the below solutions. If you're sure that you need the ability to adjust your actuator's stroke, keep reading.
Sometimes simply adjusting a mounting point could net you the same result as any of the below solutions. If you're sure that you need the ability to adjust your actuator's stroke, keep reading.
What Are limit Switches?
There are many different types of linear actuators. The simplest of these (such as our S series) have internal end-limit switches. These switches simply stop the actuator by cutting off the power when it reaches it's end of stroke when retracting or extending.
There are both adjustable and non-adjustable limit switches, with the non-adjustable type being far more common.
If an actuator does not have end-limit switches, or another means to shut down power at the end of it's stroke, damage to actuator is certain to occur as it will keep trying to drive until it burns out the motor or causes some other physical damage to the device.
Stall Protection
Stall protection is a feature found on Actuonix "R" and "I" series micro linear actuators, as well as "P" series when used with our Linear Actuator Control Board. This gives you similar functionality to an actuator with adjustable end limit switches. The difference is that while end limit switches cut the power to the motor, inhibiting further movement in one direction, stall protection is a safety feature that kicks in when the motor 'stalls' or meets a certain amount of resistance.
If you need a linear actuator with a custom stroke length, you have options. You don't necessarily need a linear actuator with adjustable limit switches. Below are 5 options to get the custom stroke you need.
1. Use an LAC board
Using a "P" series actuator with an LAC board increases the functionality of the actuator. One of the features it offers is the ability to set custom end-limits on both ends of the stroke. It's as simple as turning two pots to the desired position and then disconnecting and reconnecting power to the board.
The LAC board is not only simple to use, but it's affordable. When you buy a "P" series actuator, we offer the LAC board for 1/2 price, which is only $20. For most applications, this is going to be your best bet for setting a custom stroke length.
2. Use an RC radio
Our "R" series linear servos, are a direct plug-and-play replacement for rotary hobby servos. If you're controlling your project via RC, you can set custom end of stroke limits in most modern radios. I use a Spektrum DX8 and it offers this functionality.
3. Install an external limit switch kit
An external limit switch kit is a small mechanical switch that will either make or break a connection when contacted by the actuator at a certain point. You to set custom end limits on an "S" or "P" series actuator. It's inexpensive and relatively easy to install. If you need help installing an end limit switch kit you can find the data sheet here.
4. Use an arduino
This might work well for you if your project is already using Arduino. It's more complicated than simple limit switches or even using an LAC board. I won't cover this in detail here as there are several ways to accomplish custom end-limits with Arduino and that's a whole article on it's own. For support using Arduino with micro linear actuators, I highly recommend signing up for the forums at Trossen Robotics. There are lots of great, helpful Arduino users over there.
5. Order a custom product
If you need a large quantity of actuators, it would be a big task to install limit switches on them all. We can help you out by building you a custom micro linear actuator with limit switches set to your specifications.
This would require a quantity order of at least 500 units. If you need a lot of actuators for an OEM product than this is a great, cost effective way to get the custom stroke that you need.
The point is that you have options. You don't necessarily need a linear actuator with adjustable limit switches to achieve your desired stroke. You can get the same result several different ways. The options listed above are the simplest and most cost-effective for most individuals and companies.
If you have any questions about using a micro linear actuator with a custom stroke feel free to contact our sales department weekdays from 7:30am to 3:30pm.