What do I have to pay attention to when buying a used robot?

We have a thread in the forum where we collect ideas and share tips for buying used robots.

Thanks to all Forum members for helping to create this thread.

I have summarized the most important here.

Here you can find a checklist, that will be constantly updated in the future.

Checklist for buying used robots:

• Can the robot fulfill the tasks that I want it to (reach, payload, speed...)?
• Is the robot an alteration like (V)KRC, which does not fully support all software or hardware?
• Does the manufacturer or any other merchant still produce/deliver spare parts?
• Does the merchant give at least 6 months warranty?
• How many operating hours has the robot worked?
• Does the robot come with a manual, documentation and software?
• Does the robot come with calibration and tuning tools?
• Was the robot maintained regularly?
• When was the robot’s last “big maintenance”?
• When did it last get its oils changed?
• Is the picture in the offer a real picture of the robot or just a patterning?
• Was the robot overloaded in the past?
• Was the robot used in high heat or in a dirty environment?
• Does the robot make unusual sounds when moving?
• Can the robot be moved in all directions with all axes?
• Has the robot been tested for at least 3 hours in full speed?
• Are the plug connections and cables between controller and robot arm okay?
• Is the controller dirty on the inside?
• Can any hardware errors be found in the log book?
• Was the log book deleted?
• Can I hire a programmer for this type of robot if I need one?
• Does the robot have an CE certificate?

In general, it is important to know that a used robot can cause very high costs later on. Or you might buy one and later realize that you cannot use it for the task you intended it for or that a spare part cannot be bought.
Here in the forum you can find many examples of ambitious tinkerers who worked hard on their project and have succeeded in saving money through buying a used robot as an entry point into the world of robotics.
But there are also thousands of other robots that are now displayed items worth more than thousands of euros or dollars, serving as examples that the start into robot technology can sometimes be impossible.

Some used robots switch from owner to owner, each of them invests hundreds of working hours and thousands of euros only to come to the realization that robots aren’t for them.
Another entrepreneur who turns their back on robotics and sticks to manufacturing by hand. And one day he will realize that is competitors are successful in producing their products cheaper and in better quality.
If you don’t want to end up like that, here are the most important tips in order to make buying a used robot safer and easier:

1. Only buy your used robot from a merchant that can be trusted. Robot manufacturers don’t like selling used robots, but they have a few merchants that they trust with their service. So it’s best if you look for signs that a merchant is authorized to sell robots or spare parts.
2. Check the robot for completeness. Does it come with documentation, software, tuning tools etc.?
3. Check the mechanical system and the controller. Look out for creaking sounds, dirty cooling fins in the controller, etc.
4. Hire a professional robot programmer. The programmer costs you approximately €1000 per day, but they are worth it in the long run. You can either hire a staff member from the manufacturer (which can be more expensive) or an experienced programmer, integrator or engineer. They will tell you if the robot suits your requirements and if the robot is in good condition. And they will also help you push your project into the right direction. Especially in the beginning of a project your enthusiasm and energy might get lost really quickly if you have to invest days or even weeks into small details. Alternatively a robot training can help you a lot in tackling your project.
5. Do not buy the cheapest robot you can find from some dubious seller on eBay. In that case it would be a better investment to donate some money to your local kindergarten or to Robot Forum for giving you this advice. Invest in a more expensive product, it will save you a lot of time, money and energy.
6. Include your staff in the process. You don’t want your workers to be scared of losing their jobs to their new iron colleague. Because if they are, they will only see problems in the robot. Show your team members that the robot will only do the stupid and boring work and that they will have secure jobs in a more modern production.