Affordable Electric Actuator Ideas

For those who don't want to convert car jacks, scissor or bottle (hydraulic), heres some 12Volt variations available from China that are quite cheap. Factory speed is around 30sec to full extension, capacity from 2 ton. The last time I enquired, around Sept last year, they were around US$38 each, the scissor a bit less than the bottle. However I reckon the scissor would be easier to modify to improve extension speed.

I think actuators for our purposes have to drive at least 150mm/s.
I have doubts, that these actuators could be tuned up to this speed

30 seconds for 30cm. That's 10mm/s

Hey that's a good rule of thumb to know!

I was more thinking they could be a good start for someone that wants the mechanics and housing, and maybe just need to replace the motor. Or do you think the threading is too fine?

Personally I dismissed them myself and opted for the gearhead and crank option which gives me the speed and grunt.

Perhaps they could be made usable for general aircraft simultations (Boeing 747 etc). Maybe with some tricks which use leverage.
If someone has such actuators, and has no use for them anymore, he could try it out.
But I wouldn't recommend to buy such actuators.

If someone can tell me where I can source these babies seen on the D-Box gaming chair (they look like custom solenoids) I'd like to try and source some.



Lifting capacity: 750 lbs (total for 3 actuators) Motors: precision, brushless AC Motion: 3 - Axis Weight: 6 lbs per actuator (18 lbs total) Dimensions: 2.3 W x 2.3 L x 11.5 H

http://www.d-box.com/index.php?option=c ... &Itemid=39

Which part is 2mm round? The threaded rod?

ego made a good point with his speed estimation, the precision on these things is not too good. If it is 150mm/sec being the ballpark speed goal then the steel casing and the bushing is probably too soft for hi-speed robust use.

Aaah I get it, 2mm linear motion per revolution. Similar to a gearing ratio.
And the more linear distance travelled per revolution = the flatter the curve in the thread, thus reducing the ratio, therefore the more watts the motor has to be rated in order to rotate the extra loading.

I'm also in the search for better motors that can handle bigger weight and speeds.

The car jacks seems strong but are slow!! If I had to use them, as last resort, I'll had to attach on them an enormous pulley, or a set of pulleys to increase the final rotational speed...!

Car jacks

I have just pulled apart a scissor jack to use the thread and hooked it to a mains powered 1/2 drill and it appears to have alot of power and speed,the pitch is 3mm/ rev and the drill is capable of 2800 rpm I did a stall torque test
and it is more than adequate to lift the weight of my sim.The only problem is interfacing the velleman 8055 to it. It exceeds 150mm/sec

@CW

Based on the premise of just using the threaded rod (forgot the specific technical name) I guess I could just butcher a few of my german linear actuators (10mm/sec) and hook them up to higher speed motors!

Is the drill an AC drill? Spd Control with SCR? Noise prolly give the microprocessor fits and spaz attacks. Interesting to see how long the gearing in the drill holds up too. Happy if you could keep me posted on your outcome!?!

ego mentioned in another post that some of the old cordless drills (DC) had some grunt and hi-speed.

For a threaded rod we do not have to buy a whole crappy car lifting actuator. The rods and ACME nuts are sold in ebay for little money.
For low rev stepper these nuts are useless, but for high rev DC motors, they do the job.

That sounds really great. I'd rather use 5mm threaded rods. Thats imho the fastest ACME you can get for cheap.

I saw some double helix acme- (lead-)screws some time ago. There was no price exposed, and I havent asked... They looked very pricey.
I think 5mm ACME would be the best for our purposes, as they are cheap.

I have proposed this to you already

Yes, 24V DC, 165Nm and 3000revs/m. But those are in the 300 euro range. I think we should better forget that.

Sirnoname mentioned garage door motors. They are simlar to automotive wiper motors, but seem to provide stronger gearboxes and some more power.

All these ideas, great!
I would like to find a fast powerful DC motor, running high voltage AC through the control box could lead to safety issues, garage door openers are quite expensive here, the scissor jacks come free and with enough lube, should last, time will tell, easy to mount to the application, I too have doubts about the reliability of the drill gearbox, especially after stop start reverse torture. I have replaced 3 wiper motors to date, stripped gears and broken field magnets and they get quite hot after about two car races. (OK on my flight sim but get way more work on the car sim) have thought about car starter motors, but because they are series wired you would need to reverse the fields or commutator for reverse direction, good RPM good stall torque but current draw too high for a PWM circuit although I havent tested one yet and it would draw less operating a screw thread than starting a car engine

We have discussed this issues as well, recently. The featuere of the hydranite controller, to provide fast direction changes (up to 10 times and more) could kill a wiper motor gearbox or others, if the masses are big enough.
Thats why we want to try garage door motors rather.

Suitable models are availabe from up to 80 euro in ebay here in Germany. Perhaps more expensive than a wiper motor from the junkyard, but imho affordable still.

Do you have some additional suggestions (not AC)?

I agree, from what I have seen a garage door set up would be good but about 400-500 NZ$ here.
I saw some one on the net using 24volt wheel chair motors which would also be good,I will have a play with a starter motor and report back.

ego.
Here are pics of a stripped linear actuator.

I didn't go as far as removing the plastic nut off the barrel to see if there is a steel nut further in. The plastic nut is slippery and could be a nylon or polyethylene based plastic. The lead screw has around 10mm per revolution of linear travel. I have questions on the strength of the pin that mates the ram to the motor. The motor looks similar to a windscreen wiper type. I like the idea of direct driving off a hispeed hi torque motor. The actuator is rated to move 300kg so maybe the plastic nut is pretty good, and as you have pointed out it is TUV approved so the design must be good.
link to video of stripped down actuator
http://extremevr.co.nz/media/aKtuatoR_stripped1.wmv

question: how much torque and rpm will be required to move this more than 150mm/sec with relative ease and long-term durability. ie: not just adequately. I want the motor to be grunty and gears (if any) not to crumble.

update:
Couldn't help myself, I viced the nylon nut and managed to unscrew it off the barrel. It is 50mm long and is the sole means of threading the lead screw. There is also a plastic bush at the end of the threaded rod to help guide the barrel down it's length. Once the plastic nut was tightened I attached an electric drill onto the drive pin. At 2800RPM the ram travelled up and down quite fast. But there was a bit of vibration as the barrel wobbled at the bushing end.
Summary: If I was to follow this as a solution I would need to get an engineer to mill 2 decent nuts per actuator to stabilise the high speed wobble. I would only go down this road if my gearhead-crank system is not robust enough. As can be seen on my earlier video, spd should not be an issue with my 24Volt motors.
http://www.extremevr.co.nz/media/2of3motors.wmv 1.9mb

sirnoname.
I agree and I still feel a motor with gearbox to a crank-pushrod will be a solution. It is very fast and the motor can operate well within it's capacity. eg: inmotion style. I have concerns with the manufacturing of the planetary gearbox in the wheelchair motors of my motion platform, they are from China so the metal has to be considered suspect. An engineering friend reckons they are adequate but time will tell. Once I have my chair working I will really try hard to destroy them. I have just bought a 24V 20amp (500VA) transformer and it arrives next week so soon I will be able to crank up the juice! :shock:

Tough the nut is made of plastic (some special one), it looks way more solid than the firgelli ones, which look like crappy standard plastics.
As well the rod is as twice as thick, and looks like, as it would easily heave the 300kg.
The vibration is a phenomenon which I noticed as well within the firgellis. Perhaps this it could be minimized when using the acturtors preloaded.

Personally, I think that a belt driven gearbox would fit best, because of the nearly direct power translation, and the abilily to change the ratio easier, than cogwheel solutions.
An easy to replicate belt driven example are the ultramotion Bug actuators.
http://www.ultramotion.com/products/bug.php

With a belt translation the noise, caused by the cogwheels normally, could be avoided as well.

There are formulas to calculate the needed torque and rpm, for sure

These aren't exactly affordable but food for thought.
http://www.teamwhyachi.com/gear.htm
http://www.robotbooks.com/robot-motors.htm

@ ego

The belt drive design looks good, I like it. Smooth and ratios can be adjusted. Making one up will be a feat for me though. I will see if my engineering friend is willing to take up the challenge for a few beers. :wink:

These used to sell for less but they are built in UK so could be better quality than China. (unless they are recycled Rover parts!) :twisted:
http://www.surplustronics.co.nz/shop/pr ... T0100.html

Further afield:
(sourced from http://buggies.builtforfun.co.uk/Links/index.html)
http://www.electricscooterparts.com/motors.html
http://www.surpluscenter.com/

@Linear Actuator Mod

Good news, my engineer mate has taken up the challenge. He will look at making up a mount for the new motor and use pulleys from either a car engine or a broken photo-processor.

I will source motor from

http://www.scooterparts.co.nz/electricmotors.html

24-Volt/280-Watt - Part No: EM-002
but would prefer if it came in this style, EM-001

specs:
No load: 3200RpM
Loaded: 2600RpM
Torque: .9NM
Current: 13A
Efficiency: 76%