Worm Gears-worst efficiency

[x1610]

Hi
Dont take it so personal please,i am thinking on a freewheeling system to.
Stand open for different views please.
@ thanos :can you tel me more about the feds when stalling.
Is this a big problem,is it a bad idea to hook a smal CNC pmdc servo to a JRK21v3 and stay in there 3 amp continouis area
Sorry for my bad english

[tronicgr]

Let me explain what happens of you have a freewheeling motor with load connected on a motion controller. The load is trying to move the motor position towards the load pull direction and the motor controller is trying to maintain the position by applying opposite direction to the motor.

Now, depending on the motion controller's update frequency, it will try to maintain the position by applying short pulses. If the update rate is 1000Hz will maintain better positioning and closer to the setpoint than a system that updates only every 200Hz for example. The 200Hz will probably produce noticeable jumping and apply even more power surges in a try to maintain positioning.

In any case these freewheeling motion systems need load control feedback to maintain better position since the load may not be static because of the inertia of mass during motion. Load Cell sensors maybe??

Thanos

[Turn]

hey motiondave -

Thanks for your comments.

Are we trying to save the planet over 100watts? Or are we trying to have some fun.

hehe.....that's funny. No, we're trying to have some fun, definitely. I like the idea of throwing lots of power into an economically priced design to get the same results as spending tons of cash on an expensive one that performs no better. Believe me, I always try to remember that option with any design ideas I have. We are here for results, not for a beauty contest.

Before I go any further I want to state that I hope I haven't offended anybody who has already invested time and effort into a worm gear-based sim. That certainly wasn't my intention. If the response to my subject line is, "yeah, so what!", that's fair....

Yeah, I don't know if that sarrus linkage works for us. I posted the URL only to briefly shine a spotlight on the "design" part in the Power + Design = Results equation, that's all. He's a very out-of-the-box thinker. I like that.

I've gotta admit I'm so happy to hear those motors and the Daytons handle being overdriven so much. That's fantastic! I'll have to seriously consider getting one.

....then rip it off the gearbox and do a 20:1 spur gear setup instead (kidding)

[motiondave]

20:1 spur is fine if the motor and gearbox provides enough torque. More speed, more vibration.
I used the boat winch motors, but with only one gear on the motor, not the entire gearbox, on a seat mover ages ago.
So I got about 300-400 rpm from the motor on that one gear, but it still was controllable with a single pot and JRK.

Anyway, here we go off topic........

[Turn]

Cool.

Oh, and BTW, yes, I would have no problem saying straight to Motion Dynamic's face that that motor of theirs does NOT do 20Nm at 200W It's physically impossible. If what they really mean is it'll do 20Nm on nitrous (over driven 250%) then okay, but that's sure not what they say anywhere. A guy could reasonably hook it up to a 200W H-bridge expecting 20Nm and find he only gets 8.

But lets examine something. A car drive line, you have an engine, gearbox and final drive. You loose efficiency of about 30% from engine to back/front axles.
Should you be saying to car manufacturers that they have got it all wrong?

[motiondave]

This thread is starting to get out of hand.
Granted this is freedom of speech and we could both go on for ages over which motor does what.

Ducks guts is this.
We are DIY sim builders. We work with what works
I have built 9 different designs using wipers and big worm gear motors. Simply, they work. They move 120kg of driver plus.
Even the ebay daytons have proved their worth in showing a cheaper alternative is still good.
Regardless of stated torque figures and otherwise, there are people here including myself that have PROVED that these motors work. We don't care about power efficiency.
Floriske has the ebay daytons and loves them, he has found they move really well. Ohther builders are designing sims with them and look every good.
I use the motion dynamics motors and have sold a seat mover with them on the sim to an overseas buyer. He loves it. And he has used actuator scn5 and dbox sims.
Show us a cheap alternative to a scn5 that does work very well and we can buy it. Until that time , we sim builders have limited options and funds.

If you want to raffle on about in efficiency and incorrect torque and power figures, go ahead.

[x1610]

If a supplier is honnest is allways a big question.
I regret to say ,but there isnt a international standard for motor/gearbox specs.
All compagnies make there own specs after there own rules.
(dyadic gives a 1G acceleration for there scn5,but he is missing steps doing that)see old forum.
Spurgears arent 98% efficient to,between 55% and 70% normaly it depents on there stages.
Planetary gears are the most efficient from the freewheeling gearboxes.
I am able to reduce costs with a JRK21v3 50usd and pmdc servo 60usd but need to pay 150 euro for a planetary gear.
I was thinking to make a ballscrew actuator for les,but Thanos scared me with the loadcell.
@Thanos:Do i realy need loadcel feedback,even when the forces from the sim are the 50% from actuator trust force.
sorry for my bad english.
regards

[motiondave]

Maybe a good feedback system would be better, say a multiturn pot setup. Or do something like pictured.
I use a single turn pot with rc gears and I feel vibration at idle.
The gear setup gives me about 250 deg of a 270 deg turn single turn pot.
Just a suggestion

[Turn]

motiondave, deep breath, my friend You misread my post and, as a result, are taking this thread in a particular direction it doesn't need to go. Nowhere have I said those motors don't deliver what you claim. Period. Scroll up. I said they don't do it at 200W. Something which you yourself also stated, and were so kind to post real-world current measurements of yours which proved those motors do indeed deliver 20Nm +. Let's shake hands, and move on. Yeah?

I think it's exciting a hundred bucks will get a guy a 500W motor that'll do 20Nm! That's what I call value. And that's why I said earlier I'm thinking of getting one. The only thing stopping me is I'm not sure 500W is enough for what I want to do yet, but that's beside the point.

The consensus here seems to be that worm gears are among the best choices, not the worst. That's fine. Results is what matters and it's great there are so many people happy with theirs.

[value1]

The only thing stopping me is I'm not sure 500W is enough for what I want to do yet…

You'll be surprised how much 500W is. 500W might be ok for a stereo but it's raw power on a seat
Probably doing some maths will help you decide if you really need more than 500W.
Aldoz has built a 3DoF simulator with 3 winch motors.