Dan M

My Feedback: (1)

Tom

Since you don't own any Lado Retracts , and you never have , and since the only problems with Lado retracts were that they were/are extremely hard to get shipped to the customer ............... would you be so kind as to elaborate as to what mistakes/bad design you have found in the retracts that you don't own nor have ever owned ?

since you don't even have a pair of Lado retracts to reverse engineer and learn from , and are asking people here on this thread to disassemble / photograph their Lado retracts , how have you been able to come to the conclusion that the retracts you are trying so hard to copy are of a bad design ?

everyone agreed on the old thread that Lado retracts are the best mechanical retracts made at this time , and the only "mistake" made was Doug's inability to deliver on time , and that fact that too many excuses were made for the late deliveries.

for you to say that the retracts were poorly designed is wrong and i am calling you on it .

hopefully no one will sell you a pair of Doug's retracts so that you can copy his "Bad Design"

regards

Dan

Tko310

My Feedback: (7)

hey dan
I understand some of what you are saying. I read many of your posts in the other thread.
However, Tom has said that this is a slighty different set up if you read and follow the posts. Some of us are learning here and appreciate the time others take to teach their craft. Please, Please Please do not turn this into another pi$$ing contest.
Thanks

JimDrew

My Feedback: (16)

You could make very simple electronics for this (I did). PIC10F with a Zetex current sensor (S0-23), two dual FETs (S0-363), cap and resistor (0603). No need for A/D, yet you can measure current using this setup. You will need a voltage regulator for PIC. You could build this entire thing for dual retracts in a space of .25" x .25" if you needed to. In my case, I mounted the board directly to the motor's power wire tabs. This eliminates wires going to the motor. The PWM input is handled by the PIC so you just have a board with a servo plug. You use Y-cables to connect all the gear together to a single channel.

Dan M

My Feedback: (1)

not turning it into a pissing contest at all and i am learning too , however , Tom has no right to say that the Lado retracts he is trying to copy are of a bad design and that he is learning from Doug's mistakes , it's simply not true .

first of all he has never held a pair of Lado retracts in his hand so what does he have to reference ?

Doug's only mistake was his lack of people skills and poor delivery , his design is magnificent .

for Tom to say otherwise while he actively seeks to reproduce Doug's retracts to the point of asking others to take photos and describe Doug's gear to him is unfair and probably falls into the category of changing history (recent history) to promote his endeavor .

just making a point , (and i have) ... so i will enjoy the rest of the thread and try not to chime in unnecessarily .

sure will be a damn shame if Tom spends all this time matching up that Muzak like "Buy me now" music to his sales videos and spends hours trying to copy Doug's retracts , only to find that a major RC company has COPYRIGHTED the mechanism and is due to launch them as an entire line , ready for shipment in the very near future

regards

Dan

TOMAPOWA

My Feedback: (1)

Dan,
As with all your comments,... you really should read your own posts before pressing OK...
I NEVER asked anyone to open up their retracts... please read posts completely before making inaccurate comments... it really makes you look bad. I simply asked if any one had taken them apart for some reason...

And just so you know,... I would not accept Lado retracts if you paid me.... I want to keep my models flying!

Lado's poor design/issues? LOL.. where do I start...

If you've been following the Lado threads (read them completely that is), you would have noticed that Doug himself caught a design issue with his retracts... a bearing issue where they are cracking/seizing due most likely to excessive thrust (I know 4 ppl that experienced this problem). One of his recent excuses for not getting retracts out the door is that he's waiting on new/different bearings.... so.... expect something to fail soon on your older Lado retracts!

Another reason why Lado retracts will eventually fail/stop working properly is because like me, he uses the stall current (common practice with motor controls... not a novel/new idea) to detect end throws. BUT... In his case, this stall current measurement is factory set before shipping. What Lado did not account for is wear & tear on the mechanism, which in turn will cause an increase in current during normal operation. This would then affect the control of the retracts, causing the rectracts to stop prematurely, rather than only stopping at the end points. My design would calibrate itself every time you power it up. Now that is good, well-thought-out, fail-safe engineering!

Yet another issue is that the controlling electronics on Lado's design are EXPOSED to the elements... water/dampness and electronics do not go well together... trust me. This is the reason I choose to keep the controller seperate from the actuators... It'll be nice & dry inside the fuselage. I hope you always fly in dry weather with your Lados!

And the biggest design flaw... (again, please read through my posts here... you might learn something)... you should not run these off of your receiver voltage alone... Hint:... if you ever get your Lados working, be sure to run them off of a seperate batter/regulator... you'll thank me down the road!

Had enough...? I have more... but I really don't want to scare too many Lado owners.

If you need to keep supporting Lado, please do it in the other thread... Thanks in advance!

TOMAPOWA

My Feedback: (1)

Jim,
Check out the MC33887 H-Bridge DC motor driver.... simple and perfect for this app.
http://www.freescale.com/webapp/sps/...C33887&fsrch=1
Includes a current sense feedback pin (voltage proportional to current)... no extra current sensor needed, and interfaces to a micro very easily. I also doubt very much you can place two 3A FETS (stall current of gear motors ~ 1.2-1.6 amps) and accompanying components (PIC, current sensor, reg, etc...) in a 1/4x1/4" space. Then again, space is not a problem here as I plan to have the controller inboard (fuselage), simply to keep it safe and dry! I also plan to have my controller board control many actuators, along with maybe programmable sequencing (i.e. stagger/delays), retracts speed adjustment (via PWM) and other features I (or others) drum up.

JimDrew

My Feedback: (16)

Yes, you can fit all of those parts quite easily. The PIC10F series are 6 pin SO-23-5 packages. If you use the newer PIC10F220 you can use the built-in A/D and get rid of the cap/resistor, making it even smaller. The FETs are rated 5.9A continuous (22A pulsed), plenty enough for this application. There are new integrated packages now that are even smaller with the same current capability. Using conformal coating takes care of any environmental issues. We have had this designed for a few years, but scrapped the idea of bringing it to market when I found out about the Lado gear. We have been toying around with this again, and even have samples of some actuators from Canada that have position sensing capabilities, so they could also be used for gear doors, speed brakes, etc.

If you time the duration of the retract operation ("learn mode" the first time the system is powered up and used) you can then deliberately pulse the FETs towards the end of the cycle to prevent the binding. This way you don't have to back up the motor to relax the binding situation.

Besides giant scale, our focus is on the 1/2A size retracts, so small and light weight is critical.

JimDrew

My Feedback: (16)

BTW, I used the 33887 in a project about 5 years ago. It gets hot. There is a reason for that big heat sink on the bottom. RDs is 120mohm, so there is quite a bit of resistance and if you don't use a larger value than recommended for the CCP, it gets really hot. What I did not like about this part (and eventually had to abandon it) is that it is 5.0v only. You can't run it on a 3.3v micro setup directly.

TOMAPOWA

My Feedback: (1)

Jim,
I assume those FET ratings are with an optimun heatsink... wow...
If you are talking about the Firgelli L12 actuators... these are way too big... and costly! Want to buy two?
Plus trying to incorporate a positional feedback system into these is non-cost prohibitive... and uneccesary in my eyes. Using timing is not a good idea either as over time, with mechanical wear & tear, this required travel time will change. I do in fact also use a timer to shut down the motor just in case the current sensing fails during operation. Regardless what design you choose, you will certainly need a feature (current sensing) that can detect the retract hitting an obstruction, prematurely stopping the motor as to not break or burn anything up.

TOMAPOWA

My Feedback: (1)

Hm..? During normal operation, my MC33887 does not get warm at all... then again, I am not PWM'ing it... which makes a big difference. 5v is perfect for my application as I am using 5v gear motors.... not sure 3v gear motors would cut it to be honest, especially on the size Robarts I am moding.

Instructor

My Feedback: (16)

That is a GOOD idea, but the threads that are on the rod, 6X32, I think, are not intended for load. What you need is a Williams thread. They are threads that have a flat edge and a rather thick tooth. If you look at screw jack stands, then you will see what I mean. The 6X32 threads will wear out much faster than the Williams thread. Maybe I'm wrong, but thought I would mention it......
Larry

TOMAPOWA

My Feedback: (1)

Thanks for the input Larry.... actually the rod I am using is a stainless steel 4-40 threaded rod. So far, the gear I modified all used a trunion control "T" that is tapped for a 4-40 thread.... lucky me I guess. I'm curious if other air retract manufacturers use 4-40 or something else. I know exactly what you mean about how the threads are cut for jackscrews... interesting fact I might have to consider. I was in fact concerned over thread wear and hopefully this weekend, I'll run a test where I (actually a PIC) will constantly cycle the gear (every 15-20 seconds or so... still not realistic use but good enough for a test... I just do not want to overheat the motor.... as this probably will not happen during normal use), just to see when the unit fails... and mainly to see WHAT fails frist! I also plan to test with a brass 4-40 threaded rod as someone told me that brass-on-steel wears less than steel-on-steel..... no? I'm an electrical engineer, not a mechanical engineer (although I attempt to think like one once in a while.... LOL)
Thanks again for your thoughts....

Tko310

My Feedback: (7)

Tom
This is true brass does wear better when used on steel. This is the reason for so many brass bushings. brass has a certian lubricity to it that makes it suitable. The trick is chosing the right alloy. From my limited search and knowledge alloy 353 is often used for gears nuts and wheels

18-8 stainless steel and 304 and 316 are the most common alloys. The problem that arises is stainless has a tendancy to gall when used with steel and in truth most other metals depending on finish quality of the stainless part and lubrication.
hope this helps
Tighe O'Meara

TOMAPOWA

My Feedback: (1)

Awesome... great input Tighe!
I'm on the hunt now for some brass (or similar alloy) threaded rod... I really would like to test that combo. (or maybe a few combos) and see what works better (after I run my steel-on-steel setup this weekend... and see what breaks first!)

Tko310

My Feedback: (7)

Try looking at Mcmaster.com This is McMasters Carr's website almost anything you could want
as far as the mechanical stuff goes

DPKII

My Feedback: (2)

Larry, is correct on the threads. Also called ACME i think. 4/40 threads are fine pitch and may lead to wear issues especially if brass is used. You may also check for binding when the threads get a little dirty. Oil,sand,grit, etc.
Just food for thought. Keep up the good work.

David

Tko310

My Feedback: (7)

Acme is another name, the laymans term is worm drive though usually associated with drives containing ball bearings or the like.

Acme threads are ideal for a couple reasons
- they can bear much more load due to the angle of the thread which would reduce some load on the motor. However, friction at the trunion cross bar would increase.
- they will likely not cause the galling I stated earlier because quality acme thread has a ground finish verses a cut finish. This eliminates some of the surface defects from standard cutting.

Reasons they are unsuiteable
- the smallest manufactuerd size is 1/4 in
- standard pitch ranges for 1/4 is 8 tpi -20 tpi so the speed of the actuating motors would need to change
- taps are availabe for the cross bar however they are expensive.

not trying to be a PITA just sharing my experience

JimDrew

My Feedback: (16)

I think you misunderstood my intentions on timing. If you time the duration and subtract a certain amount you can use that as a reference point of where to slow down the motor to finish the remainder of the cycle. This eliminate potential damage if a bind were to occur at the end of the cycle, and this completely removes the need for spinning the motor the opposite direction to "relax" the threads. Running full tilt until the current sensor kicks in is too late, and the reason you are having to back it up right now. If this process is repeated over and over again, something is definitely wearing out quicker. Just a suggestion...

TOMAPOWA

My Feedback: (1)

Thanks Jim, I see what you are now saying... I thought you were trying to eliminate the stall current sensing all together...
I could certainly try that... but I have a feeling that even if the motor was slowed down a little, it would still have to experience a specific stall (i.e. torque) before shutting down. Maybe slowing it down like you said might not bind it as much.... I'll have to test.

I also found something out interesting late last night. I was pausing a little (200ms) before backing up the motor after sensing a stall condition... and in doing so, the mechanics would work 20-30 cycles until it would bind and not move when under control. What I did was then remove the pause such that it would immediately back up a little just as the stall conditions was sensed. I have since cycled the gear 40-50 times with 100% success! Go figure!

Infantry2114

I have to say if some-one can come up with and electric retract and can produce them and get it to the customer in a timely fashion will make alot of money! I ordered 3 sets of electric retracts from LADO Retracts on 10/1/09 and 10/8/09 and now it is 12/9/09 and still have not seen my retracts! I have personally call numerous times and emailed Doug and to no avail. I read the post which stated that they were worth the wait, maybe so, I readed the post that stated that Doug replied back to them and explained the deal. He has $537.62 of my money, I may have to go into the retract business if i can get away with that.....I have been in the retail business for most of my life and the customer is the one that paid my bills and supported my hobbies all these years. Granted I am not trying to bash no-one personally I just want my money or my retracts is all. I will wait for a little longer but if it goes for a few more months then I will resort to call the BBB to resolve this issue. Hope to see you in the future TOM! Good luck and nice video......

JimDrew

My Feedback: (16)

No, actually this makes sense (and the reason why I suggested the slow down just before the end). When you pause that 200ms with the motor power off, the motor is still spinning down and the gear train is still moving for another 200ms (which makes the it turn quite a bit). When you immediately back up the motor, you are preventing it from going too far by halting the movement and changing directions. Slowing down prior to the end will prevent any possibility of binding because of this "overlap" due to the gear train spinning down.

TOMAPOWA

My Feedback: (1)

Hi Jim,
Actually, the way I am controlling the H-bridge, I am "braking" the motor rather than allowing it to free-spin until friction stops it (maybe this is helping too). Certainly slowing it down should help you would think... but I am really trying to avoid using PWM unless I have to... causes excessive heat (MOSFETS switching) which I am also trying to eliminate. Actually, last night I added two (vice one) short 20ms reverse pulses just in case the first one does not work... Cycled at least 40-50 times last night with no binding... amazing. This weekend I hope to run more extensive tests... in an attempt damage the actuator if I can. I'm real curious what will fail first (any one want to take a guess? Maybe I should had made a poll as to what they think will breaks first... LOL). I plan to run it till something breaks, regardless! Should be fun! I wonder if Doug (Lado) performed this type of failure analysis/test before selling his gear?[8D]

As a side note, I am also messing around with a cool idea, using a optical reflective sensor that monitors the rotation of the shaft/coupler... this could also be used (along with current sensing) to determine the approximate position of the screw drive... but I think I might be over-engineering, something I tend to do all too often!

F2G-1

My Feedback: (13)

Wow, great job! I wish i was as electronically savy as you guys.

Been following your thread like a hawk. I have been working on my fowler flap system for a couple weeks now, and some of your techniques may have use in my application.
I'm going the limit switch route, as i have a little more room to play with, needing a 4" stroke. A load sensing circuit would probably be a good addition.
Would your setup work as a in line plug in (for redundancy), with limit switches also. I'm not using any interface, just a simple 3 way switch (closed/half/full) run by a servo. (but if i had your knowledge........)

I'm also considering the L12, but wow are they expensive. (i would need 4 to 6) do you want to get rid of yours cheap?


How did you connect your motor output shaft to the threaded rod?

Keep up the good work, mabe we can electrify my 310R's retracts!

TOMAPOWA

My Feedback: (1)

Thanks F2G-1,
Nice looking plane btw!
As for flaps, I would simply use standard R/C servos as you will (I assume) need proportional (R/C) adjust for your flaps... maybe one day servo manufacturers will incorporate current sensing technology into servos as to not strip gears when they exhibit excessive torque/current.... surprised they have not done this yet... great for certain apps I would think. That 4" stroke you said you need might be an issue though... maybe you could use a bellcrank or something mechanical to increase (multiply) the throw for your need. The Firgelli L12 actuators have over-current protection and the model I purchased also has R/C proportional control... I opted to use them instead for an ongoing home automation projects I've been also working... not tiny or cheap but nicely made! Certainly adding current sensing to a limit-switch designed actuator would be a good idea... the more fail-safes, the better I say.

Out of curiosity, re: that gear (310R) you have... Which Robart retracts are you using? There are some models I noticed (fancy large scale ones) which I know my actuators would not work on... simply due to the design nature (they do not use a trunion and/or T-control bar)... my buddy has a pair I was hoping to mod for him in the future. He now might sell them and buy a set that will be more easily modifiable.

Oh, almost forgot... my father milled me a few custom couplers that are 5/8" long... one end has a 3mm hole to accept the gear motor shaft while the other end was drilled/tapped for the 4-40 threaded rod. Red loctite hold the threaded rod into the coupler while a set screw (blue loctite) holds the coupler to the motor shaft. I also found a source for similar couplers... one end 3mm while the other end is 2mm (you would just need to drill/thread the 2mm hole for 4-40)... but surprisingly they are not cheap ($9-10 each in bulk even).

Tom

F2G-1

My Feedback: (13)

I found a set of Robart's at the local hobby shop for the TF giant P-51, in the clearance bin, marked down so low I couldnt pass them up. Shortened the strut, switched a few things around, and vwella! they worked! surprisingly very minimal modification. I ended up saving $190.00 Cant beat that!

Unfortunatly, the way the wing/spar plug ins are designed and the retracts taking up some room, I cant get the reqired space for an internal bellcrank or nyrod pushrods, w/ out drilling thru the spar/spar pockets.
In this case, linear is the best way to go, as i do have approx 7"x2" space between wing ribs on either side of the flaps. The L12'$ will fit, but hey, I got a kid to put thru school !

I ordered a L12 and some gearmotors to play with, I just need a source for micro limit switches (i only need three settings), adapters (send me the link to the ones you found,- i got taps) and some other micro hardware. The chasis platform, flap track, and leadnut horn i'll have machined out of aluminum. (thank god for buddies).

For your thrust bearing issue, I'd try the RC car guys, they got allot of small parts!