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[on:]

Finally got them to work.  Turns out one of the PWM pins on my Due is not working right.  Boo!

Would any of you know where to get a $20 linear actuator?  These are way too expensive for hobbyists, which is a shame.

[Reply #1 on:]

I found a source for used $25.00 linear actuators (6 inch travel) - but they aren't in great shape, and are fairly large (I suspect they were for electric wheelchair seat positioning); I don't have the link handy right now.

If you're looking for something cheaper, then homebrew is where you'll find it; basically couple a gearmotor's output shaft to a piece of all-thread, and put a nut or threaded coupler on it as the "traveling nut", then fix the motor in a housing, and a nut to a hollow extension (many possibilities here, from complete homebrew to using common plumbing fixtures and the like).

Note that you won't get the snazzy features like end-limit switches, position sensors (linear pots), or optical encoders with the homebrew method, but generally these can be added elsewhere into the design of whatever you're moving with the actuator (or in the case of the encoder, you might be able to find a gearmotor with one attached).

[Reply #2 on:]

If you're looking for something cheaper, then homebrew is where you'll find it

Don't forget the need for thrust bearings. Roller skate bearings might do.

[Reply #3 on:]

Homebrew is great if you want to trade time for money.  I prefer to get off-the-shelf components whenever I can.  My ultimate goal is to make a robot that others want to buy.  I want to do this for a living.

[Reply #4 on:]

My ultimate goal is to make a robot that others want to buy.  I want to do this for a living.

You could start out by making those $20 linear actuators. If they are any good, I'd be a customer.

[Reply #5 on:]

Homebrew is great if you want to trade time for money.  I prefer to get off-the-shelf components whenever I can.  My ultimate goal is to make a robot that others want to buy.  I want to do this for a living.

You wrote:

These are way too expensive for hobbyists, which is a shame.

You didn't say -anything- about this being a potential commercial venture. If you are really pursuing this to be a commercial venture, I am sure Firgelli likely has a price break for a certain number of pieces ordered, just like other manufacturers.

I do agree with you that linear actuators are expensive for hobbyists, but them's the breaks!

[Reply #6 on:]

My ultimate goal is to make a robot that others want to buy.  I want to do this for a living.

You could start out by making those $20 linear actuators. If they are any good, I'd be a customer.

This, too; I just ordered one of these for my UGV project:

http://goo.gl/vbBle

24 volt, 6 inches of travel, though fairly powerful (4000 N - definitely need limit switches and such with that kind of rating!) - still, $34.99 (I misquoted the amount before, my apologies). I don't really consider this a lot of money, though, for a used commercial linear actuator.

Even so, I would love to see a cheaper source for hobbyist linear actuators.

[Reply #7 on:]

ooooh, I also got two Linak actuactors laying somewhere... Not sure what to do with them, only got them because they were cheap.

Maybe a half powerfull robot arm of some kind? hmmm

[Reply #8 on:]

Just got my Linak actuator today - I should've read the spec closer before ordering; I had no idea how big it was!

 

The UPS guy came, dropped off the box, and my wife asked me what I had ordered that was so large (she answered the door). I said "a linear actuator - but it only has a 6 inch stroke" - the box it was packed in was about 18.0 x 18.0 x 4.0 inches, and it weighed a lot. Now, there was a bit of packing, but that actuator was at least 12 inches long from mounting eye to eye in it's fully retracted state.

I wasn't expecting something that large, but I think I have an idea on how to mount it on my robot...