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Yeah, that's pretty much it. Use the guts of an existing linear actuator combined with a bigger motor in order to give you more speed and lifting force - I'd say pick up a lower ratio (high speed) actuator and just put the new motor on it, junking the attached gearbox. I suggested the cordless hammerdrill motor as they're relatively powerful and commonly used in robots - a Speed 900 or something would be ideal too.Quote:
Originally Posted by daliad100
That certainly beats my way.
A lot easier than a full diy linear actuator and probably more efficient if there's a ball unit.
Something in this link might apply to your motor change over if you do want to do that.
http://www.instructables.com/id/Cord..._for_about_40/
Aha, you misunderstand me :-
I understand how a ball-screw actuator works. What I don't understand is the switching of the drill and the actuator motor. The screw, that turns inside the threded..um..tube-thingy, is powered by a motor..You want me to substitute this original motor with a hammer drill motor?
Pros?
Cons?
Lastly, I was once warned about using hammer drills by a certain Gary Cairns. Could I not just use a normal drill?
Alex.
Pros - your actuator will be more powerful and (RPM dependent, that's why you want to choose a relatively high speed one to start with) faster moving.Quote:
Originally Posted by aero_storm
Cons - slightly heavier? takes a bit of effort? Really, for this application, there aren't any.
A hammer drill motor isn't necessary, something like a Speed 700/900, RS775, whatever will do the job just fine - just that a lot of people tend to use Dewalt cordless hammer drill motors in robots for something with a bit more grunt than a drill motor.
A normal drill motor (usually a 550 size) won't be as powerful, which is the problem. His warning was against using a hammerdrill gearbox setup - you'll just be using the motor alone if you go that way. I suggest picking up a suitable motor separately rather than getting a whole drill.
Pros:
A pre-built actuator unit (less messing about)
Exchanging the motor makes it more powerful
Could be more efficient (ball screw not acme)
Cons:
Hammer drills are a pain to use the gearbox of it with, they have extra weight for something you no longer need.
Hammer drills have an annoying (in this circumstance) recriprocating thing to provide the hammer action which is not a problem if you are just replacing the motor.
If your actuator has a ball unit (less friction) it needs a brake or it could be pushed back down unlike an acme thread which can't.
A Hammer drill was suggested because it genrally has a more powerful motor than an ordinary drill. If you could get hold of a cheap/broken (motor dead) actuator then replace the motor with that of the hammer drill or morot of your choice.
If you would like a look inside a hammer drill then I could post some pics of the one I pulled apart (the disassembly was pretty much the same as a normal drill.)
Finally, don't use a nu-tool as my drill decides to start smoking once you run it for a minute or two under no load.
Thanks all.
At the moment, I'm veering toward the Just buy the simplest, cheapest one, less will go wrong. Please remember this is my first Robot..
Does anyone know any Actuator venders? It seems that if I had a list of websites that sell actuators, it will be easier to compare Speed, Lifting..um..capacity (?) and price.
I know I'm asking a lot, but...
Alex
Hi aero_storm,
The actuators here are not cheap but you can see the data sheets to compare Speed and Lifting capacity.
data sheets are .pdf files (adobe acrobat documents).
http://www.techline.linak.com/Products/?id3=142
Stumbled upon this video again and thought that might help if you do decide to go the route of motor swapping ...
http://www.youtube.com/watch?v=DCuk5Hp9QC0