My team is thinking of using the new Rev Linear Actuators this year. But we aren’t particularly familiar with this kind of mechanism. Could someone help lead us in the right direction for calculating what kind of gear reduction we need to move our load?
We are still early in the process but I generally know the load is split by two actuators powered by NEOs and the load is roughly 15-20 lbs.
I’m going to start with this: I think these are way overpowered for this application, particularly with two of them.
Now to justify that.
First: Two actuators moving the same thing need to be in sync. Kind of like having 2 motors on the same side of the tank drive be in sync, only you need to be as close as possible.
Second: The calculator. You actually weren’t all that far off–the missing info was that the REV actuator is an ACME thread (hover over the “Thread Angle” text to see why that’s important). Add your force applied and your desired speed, and you should get most of the rest of what you need. Then there’s a second calculator linked from the first–use that, plus the ratio calculated from the speed to get the NEO gearing.
Thing is, you’re putting a 20-pound load over two of these. That’s 10 lb each. The torque loading is about a tenth of a NEO’s non-reduced speed, and you’ll be reducing speed (increasing torque.
First of all thanks so much. That is already a big help.
Ok, I see that now. The reason we have two is so we lift both sides of something. I could see some kinda of dead support on one side but I’m not 100% sure that would work. The motion and compactness work really well for us and I haven’t really found a comparable mechanism. Would you have other suggestions? To some extent, I’m also just ok with them being overkill this year and just know we will use them in future years.
Besides that, there’s also “looking online” (with a caveat to check your voltage and amperage), or just going with both. There might be a way to support both sides with one actuator used “unconventionally”.
And if they’re overkill, they’re overkill–at least you won’t have to gear them down much!
For anyone wondering how this stuff works or how to do the calculations by hand, the lead of a lead screw is the linear displacement traveled in 1 revolution. So speed in rpm times lead in mm equals speed in mm per minute. The big difference, in terms of calculation, between lead screws and wheels is that lead screws are very inefficient in general, so you need to know what type of screw you have and how efficient it is.
Also, screw pitch is distance from one thread to the next traveling in the direction of the rotating axis. Lead is the displacement when you follow a thread through 1 revolution. Single start screw (most screws) have the same pitch and lead, but multi start screw will have a lead equal to the pitch times the number of starts.