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  1. #76
    Ravivos's Avatar
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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Hi Tom,
    Your idea is fantastic, I designed my own electric retract using solidworks, it worked great on paper (actually - screen) but never got to build one due to unavailable motor and gear reduction system.
    Now, when I see your thread, i am amazed on how well the idea works.

    Great ingenuity and engineering!

    now, some questions:
    - can you give me a link to the specific motor and gearbox you used?
    - regarding the software for the PIC, i saw that when there is a high current sensing at the middle of way (some kind of obsticle - like your hand ) the motor backs up to its previous end position - did you used a timer ? How does the software knows that it is an obstacle and not one of the end position?

    Again - absolutely fantastic.

    Raviv.

  2. #77

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Thanks Raviv,
    The gear boxes I am using are sold by many.... this is smilar to the one I am using...
    http://www.pololu.com/catalog/product/998

    The current sensor is integrated into the H-bridge I am using... and the PIC simply reads this output (voltage propotional to the current draw) and determines if an over-current condition (i.e. the motor stalling) is sensed. Regardless when the over current occurs (whether an end-point or an obstruction), the motor will abruptly brake, then back off a bit as to not hold in a bind condition. When sensing an obstruction, it does not return to its previous position as there is no way to differentiate between it sensing an obstruction or endpoint. The timer idea was pondered, in an attempt to differentiate between endpoint and obstruction, but I have not experimented yet with that idea.... certainly feasible it sounds (setting this timer value could be a little tricky as some modified gear could take longer/shorter times to reach one end point to another).

    Tom

    p.s. I still have not run that test yet to constantly cycle the modifed gear till something breaks... maybe later tonight. I also need to write a little code to also count the # of cycles before it craps out... darn work/holidays....

    ORIGINAL: Ravivos

    Hi Tom,
    Your idea is fantastic, I designed my own electric retract using solidworks, it worked great on paper (actually - screen) but never got to build one due to unavailable motor and gear reduction system.
    Now, when I see your thread, i am amazed on how well the idea works.

    Great ingenuity and engineering!

    now, some questions:
    - can you give me a link to the specific motor and gearbox you used?
    - regarding the software for the PIC, i saw that when there is a high current sensing at the middle of way (some kind of obsticle - like your hand ) the motor backs up to its previous end position - did you used a timer ? How does the software knows that it is an obstacle and not one of the end position?

    Again - absolutely fantastic.

    Raviv.
    TOMAPOWA

  3. #78

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Tom

    Great Move , This is what we need.

    Why don't you just offer a retro fit service for what is out there already, We send you our stuff and you make it work.



    Dave

  4. #79

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Tom, if you mounted a thin (.031") PCB the full length of the drive shaft length, you could use a simple (yet effective) trick to read the position of the shaft by measuring the capcitance/inductance of the PCB traces as a small nut (attached to the shaft) moves back and forth on the shaft. I designed a servo for our new pico series receivers that uses the same technique. It works well enough to act as a pot for a servo position control, so it will be more than adequate for this application.
    Jim Drew, CEO/President - Xtreme Power Systems

  5. #80

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    ORIGINAL: JimDrew

    Tom, if you mounted a thin (.031'') PCB the full length of the drive shaft length, you could use a simple (yet effective) trick to read the position of the shaft by measuring the capcitance/inductance of the PCB traces as a small nut (attached to the shaft) moves back and forth on the shaft. I designed a servo for our new pico series receivers that uses the same technique. It works well enough to act as a pot for a servo position control, so it will be more than adequate for this application.
    Interesting idea Jim! I just wonder about the accuracy (i.e. precision) of this setup... any #s you could share?

    BTW, I did get to write a little more code to constantly cycle the gear last night. I had them cycling (up/pause 3-4 seconds, down,. pause 3-4 seconds) and this repeated for over 40 minutes (I was building other things in my workshop at the time... eventually the whirring noise was getting to me!). During that time (40+ minutes) it had cycled exactly 168 times... with no hang-ups and/or other mechanical and/or electrical issues... amazing! Not once did they "stick" in either direction, nor was there any heat generated, that be the motor, h-bridge control circuit, etc... Room temp was 68 degrees and IR temp measurements shown that the motor temp was a mere 72 degrees (everything else was room temp). I plan to take it all apart later tonight to inspect everything to see if there was any wear.

    The only thing I did notice is that the enclosure I made (see attached pics) to hold the motor (two pcs of "C" shaped aluminum that fit into each other) had exhibited a little play (motor a little loose but not all too bad). This might had been caused by the method I'm using in holding the motor forward into the front aluminum pc. The aluminum pc. that pushes the motor forward does so by pressing up against the back of the gear motor and that part of that motor is plastic (plastic backplate on motor where brushes extend from). Most of the force when pulling up the gear is placed on this section of the motor and I have a feeling that that plastic had worn a little, giving the little play I now see. The gear motor's front plate is tapped for two small screws and I could always attach the motor to my frame this method also but... I simply did not have small enough screws (like those used in eye glasses... not sure of the strength these would have actually... but probably worth trying) More investigating tonight...

    Overall... I'm surprised myself as to how well this simple system works... certainly well enough I can trust to put back into my 1/4 scale Zero! (my main intention of these DIY actuators). If these appear to work, I plan to build another pair for a large scale electric pattern plane I have,... those darn retracts (Robart mechanical) are a real pain... already burned up a retract servo since setup is a real pain.
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    TOMAPOWA

  6. #81

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    I went ahead and ordered one Sanyo motor to install in my Cessna 310 retracts. I had planned to use simple limit switches in the wheel wells...but what is the possibility of buying (or getting detailed building instructions) to install the electronic package you've put together?

  7. #82

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Hey Boeing314,
    It's probably a little too early yet in the design phase but certainly... I'd eventually like to make a PCB that would easily allow the DIY'er to build their own like I did. It would easily just plug on to a Pololu H-bridge board (good for controlling two servos)... something more commercial could certainly be built much smaller/cheaper using surface mount components (single board). I could probably also offer pre-programmed PIC for the DIY'ers that also like to build the circuit themselves. Over the Holidays (actually... between them) I also need to work the PIC code a bit (input filtering, failsafe stuff, etc...) and hopefully in a few week, I'll have a complete system (two retract & controller) built and installed in my Zero. I also plan to fully document (pics, writeup, etc...) the modification of my other Robart retract for the same Zero... so hopefully in the near future I'll either post something here or on my webpage which I'll supply a link to...

    ORIGINAL: Boeing314

    I went ahead and ordered one Sanyo motor to install in my Cessna 310 retracts. I had planned to use simple limit switches in the wheel wells...but what is the possibility of buying (or getting detailed building instructions) to install the electronic package you've put together?
    TOMAPOWA

  8. #83

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    OK, sounds good. I've been wanting these ever since I heard about them...wonder why it took so may decades for this idea to finally come to fruition?

  9. #84

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    OK, got the motor in today. I hope to be able to take some parts to work in the next few weeks to get it working.

  10. #85

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Happy New Years Guys...
    I've been reading this thread with great interest. I do own several sets of Lado's and for me, it was sad to see that Doug shut down his operation, with all his problems. I do believe that any one that can produce an electic retract, for .40-.60-.90~1.20 and 1/4 scale, will make money. Right now I need a set of rotating .90~1.20 gear for a large F6F...and the only company with gear ths size is being sold by Troy Built Models (KMP style) and are air driven. I love my Lado's and they work great for me. Electic retracts are not only simple to install, but much easier at the field to deal with, with less problems. I had two sets of the old Kraft electrical retracts and used them on several models until they were no longer servicable.

    So my best to you and your indevers and I pray you end up marketing your products (yes...products for I want them in all sizes for all types of models).

    Happy New Year,
    Bob Paris
    AMA 15016
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    Say what you mean, mean what you say...and !#$& it if you can\'\'t take a joke.

  11. #86

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    it would be nice to see a retrofit motor for air gear available commercially.

    like Bob Paris, I like my LADO's as well, but I still have more air than electric retracts, and would welcome a reliable conversion for my air gear,they all leak eventually, BTW the Century Jet 60 size gear has the same basic set up as the Robart's with the same piston location give or take a mm.

    so far your ideas here TOMAPOWA is the same basic ones as LADO's, having opened the cases your retrofit looks about the same,from the outside.

    after reading your coments on the motor mounts, this issue it seems could be solved with a machined case like the LADO's use,or a laticed 3 sided mount,that could be made by stamping and some light machine work,like the robart metal bodied gear.

    the CNC was a contributing factor in the slow production runs of the lado gear, your U shaped proof mount just looks as though it just needs some top or bottom support to spread the torque load.

    the air piston on the CJ's, and my Robarts, coming in at aprox. the same Dia.,would be a easaly adaptable set up, by simply adjusting the length of the jack screw to accommodate the different brands.

    the circut board in the lado gear is actually well protected from exposure, so if you were to incorporate it into the actuator like Dougs were, it would be less components to deal with, not like plugging in another connector is a big deal,but a extra plug is another little bit to fail, the public does like simplicity.

    the stagger switch that was offered was a pretty slick little option as well I did get one before the also became unavailable.

    if you were to pick up the ball and run with it I am sure there would be a considerable demand, I certainly would be willing to give it a try not having to deal with air lines is a major plus.

    sadly I was a big LADO supporter having had no trouble with the product,even with the long waits in shipping etc...,but as the phone calls stopped getting answered and the emails are never returned its apparent that a alternative is needed to fill the void left by his company, I like the idea of a retrofit unit since there is so many air and mechanical retracts out there allready.

    good luck hope to see a finished product eventually

  12. #87

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Hi Tom.

    I've been following your posts and I want to wish you all the best!!!! These retracts are an idea that finally have seen their time. I'd be interested in doing some testing for you and if you'd like. BTW, have you been keeping track of your build costs (your time, materials, and associated build costs). This will be very important to determine your costs if you choose to make this a production effort. Also, don't do what Doug did. That is, don't turn down help and assitance. Over the last year I offered him assitance (as recently as a week ago) with his production, marketing, and even financial side to improve his business process since he had a really good idea (and product) but just bad business skills. But sadly, he never responded. I'm pretty sure I'm not the only one who offered him help. My company specializes in working with small companies who have a product or service and need to develop the business accumen to bring them to market. We also assist people in finding partners and vendors to help build/provide the materials needed to develop the product. Again, when Doug was having what he claimed was supplier issues, I emailed him and offered to help him find a better vendor (at no charge) - but no response. And the biggest thing to remember (and also where Doug failed) is that people will be happy to wait for 2-3 months for a product if you communicate with them. But you can't tell someone it will take 2 weeks and then not communicate and/or deliver for several months. I too when I started my business many years ago fell into that trap of wanting to deliver unrealisticly sooner than possible. I lost alot of clients that first year because of not communicating with them effectively. Thankfully I learned from my mistake very early and customer communication (even when it's bad news like being late on a project) is appreciated and as a result I haven't lost a client since for that.

    BTW, you may want to move quickly (but as perefectly) as possible. Horizon has already released their .15 size electrics and based on the price point their scaled up ones (which are probably just around the corner) will price in about $20-$30 more for .40 size and $40-$60 more for the .60 size. And knowing Horizon, they're going to go all out. Robart is far behind in this area since they have invested so much in the air retract arena and it's their core business (which they haven't really changed in many years).

    Best of luck and if you need some help, etc, feel free to email me or PM me.

  13. #88

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    If I were betting I would bet that we are going to be knee deep in electric retracts before the summer is over. Everyone and their monkey will have a version to sell with struts, color cordinated and I can't wait!!!!! The price will plummet and most ARF's will include a set just like motor mounts and fuel tanks. Mechanicals, retract servos and pneumatics will be worthless. But, what do I know????????

  14. #89

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Hi Folks,
    Finally getting back to my plethora of projects here, after the Holidays and all....
    I worked the firmware a bit more and even got a 2-actuator version up and running. I'm still working a few firmware bugs and a few mechanical issues but I finally got my two Robart Air gear modified with two of my actuators and all appears to be working to my satisfaction... and will be going back into my 1/4 scale CMPro Zero in the next week.

    I also added a cool stall learning function that will allow the system (actuators and controller) to easily be adaptable to almost any air-operated gear out there... more testing to follow on some Sierra Prec. gear my buddy is loaning me.

    Here's the latest video.... I'm also putting together a DIY webpage for this project and hope to have it up in a week or so. I'll be sure to post the link here when available...

    [youtube]http://www.youtube.com/watch?v=DPlZB6p_-Lc[/youtube]
    TOMAPOWA

  15. #90
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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    [sm=thumbup.gif]Great job, I'd love to use this in my TF Staggerwing, the retract frame & housing is similar to your zeros. I know I can 'DIY' it on the actuator mechanics, but the electronics will be a problem. Any chance you might eventually sell a controller set up as a ready to plug in unit? (for us [sm=drowning.gif]electronically challenged)

    Your website is great! - many cool projects- everybody here should do themselves a favor and check it out!

    Ted


  16. #91

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Tom, im watching your retract modification with great intrest. Ive bought almost all the materials etc for making a Ziroli Corsair. Im working on making the main rotating retracts and now instead of using air ill go with electric. Do you think the same gear motor will pull up some 6" wheels? Still havent put much thought to the retractable tail wheel but will probably go the same electric route using a separate board.
    Joe

  17. #92
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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    I too am very interested in your ingenious alternative(s) to modify air retract systems. My current project is a TT 1/7 Sept Fury (its been over a year since I reopened the box!) and I definately don't want the supplied gear to be trusted to this beauty. Over the many years at the field (well maintained grass) I've watched the problems surface with ALL retracts except for one plane (going on 2 years old) and found out this modeler used a system by Lado. The only planes I have retracts in are my 40 & 60 Ultra Sports. The wire struts have been replaced, rebent and well they're a pain but I love the planes. Well, as y'all can see I've joined in today because 1: very interesting posts and 2: Lado has stopped taking orders. UGH! If only I'd ordered back when I first got the plane... sooo it appears you will have quite a following in time, include me of course.

    I hope that you will consider selling the electronic board, I've never seen features like it! Count me in!

    BTW what ever happened to Likes electric retracts? I never saw them at our field, but they appeared to be extremely HD when used by other builders at some of the fly ins I've attended.

    John
    Highest award winnings for low perverted passes

  18. #93

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Hey Folks,
    Thanks for all the feedback. I hope to make another PCB this weekend (for use of a PIC16F684... the 688 does not have PWM for my planned servo output channels for additionally/optionally controlling retracts doors/hatches using 2 standard servos). I'm still pondering more ideas re: actuators. Actually, I wish some one already sold miniature linear jack-screw-like actuators like the ones I built... I'm sure they would look & work better! Plus, I could then spend more time on the firmware... more of my specialty. Being a perfectionist, I still can not get used to that 1 out of 50+ stalls were the actuator actually gets stuck (a cycle or two usually frees it). I'm almost certain that the jiggling around in the wing when rolling down the runway and/or during flight would jar the slight bind enough to stop the issue.... but still... it bugs me. I know position sensing (i.e. potentiometer, hall/photo sensors, etc...) would be ideal, but I still would like to make these so they would easily adapt to most air retract gear out there... since of course, the throws for up/down locks vary for each retract mechanism.

    By using one thrust bearing (3mm ID, fits perfect over motor shaft), I lock the coupler onto the motor's shaft so the coupler presses up against one side of the bearing and the other side of the bearing sits on top of the motor plate where shaft exits. This bearing basically stops the output shaft of the motor from being pressed into the gear box, hence binding the attached gear up against a secondary back plate (i.e. friction). Most of the force on the actuator is in this direction so the bearing here works pretty well. What happens though is when the actuator is bringing the gear/retract down, at the end (gear full down) and the motor stalls, the shaft of the motor is pulled... hence pulling the output gear up against the gear box's front plate, again causing a bind situation (no bearing can be placed inside the gearbox to stop this...). So, (pics below) I came up with another idea that sort of "captures (push/pull) the coupler inside two bearings, allowing all the push/pull force to be placed on the two bearing instead of pushing and pulling the motor's output shaft/output gear. Last night I made a quick mock of the setup (things off centered, but heck it was a test). The two bearing press into two parallel holes drill in opposite ends of a pc. of aluminum channel stock. The coupler allows the motors output shaft to ride inside one end of the coupler (loosely, with set screws slightly loose so shaft can move in/out) while the other end accepts a pc. of 4-40 threaded rod. I haven't run any test yet as I need to make a better test model... Yup, probably over-engineered, but that's me!

    Any one else want to manufacture these actuators???

    I'd rather stick with the electronics!

    I'll try to post more later this week. I'm also working a DIY webpage for the project too... tougher than I thought...
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    TOMAPOWA

  19. #94

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Tom, Is the binding issue from the motor when cycling repeatively or from the threaded shaft into the gear or the gear mesh. I cant see by the video if the threaded rod travels parallel to the to the gear frames or if it pivots for alignment. I have seen a couple different styles of retracts where the cam travels parallel in the side frames and some where the frames are arched with up and down stops milled in them. If the coupler or the rod doesnt give to the drive I could see some binding. Could a coupler be used like in this attached link http://www.ruland.com/ps_couplings_flexible_pcr_a.asp to take up for any alignment issue? I have PCR12A couplers and they are flexible to some degree and may possibly eliminate your thrust bearing.
    Joe

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    ORIGINAL: joefroooo

    Tom, Is the binding issue from the motor when cycling repeatively or from the threaded shaft into the gear or the gear mesh. I cant see by the video if the threaded rod travels parallel to the to the gear frames or if it pivots for alignment. I have seen a couple different styles of retracts where the cam travels parallel in the side frames and some where the frames are arched with up and down stops milled in them. If the coupler or the rod doesnt give to the drive I could see some binding. Could a coupler be used like in this attached link http://www.ruland.com/ps_couplings_flexible_pcr_a.asp to take up for any alignment issue? I have PCR12A couplers and they are flexible to some degree and may possibly eliminate your thrust bearing.
    Joe
    Hi Joe,
    Yes, on the Robart retracts I mod'd, they are milled with a slight up arch on both ends (mechanical lock which is important... without these mech. locks, the force will always be on the actuator... which is bad for obvious reasons (will eventually strip threaded rod). The motor will therefrore only stall when reaching each end point where the threaded rod can't push or pull the trunion any more. When the retracts approach either lock state, the t-bar which pushes/pulls the trunion rides up into the upwards machined slots locking the gear. When this happens, the whole actuator (incl the threaded rod) is able to pivot up and down (notice pivot pin holding the retract onto the existing Robart retract frame, similar to how the air cylinder was mounted). This pivot allows the actuator to self align, hence no bind issues there. I'll see if I can get a better closeup vid of the mechanics and post...

    These forces on the threaded rod are transferred (via coupler) directly to the motor shaft which is attached (via set screw) to the output spur gear. When the output shaft is pulled, it binds the spur gear up against the gearbox faceplate. If you were to push the motor shaft, the same spur gear binds against another intermediate spur gear (since inline on one shaft) which then binds against another faceplate on the back of the gear box. Hence the reason why I am now trying to isolate this push/pull force from the motor's output shaft... The single thrust bearing idea works well but I think I can improve on the design a bit.

    It's funny you mentioned Ruland... I just got (as I requested) my Ruland catalog in the mail last week... I looked at these months ago but think they are way over-priced and most likely not needed (there's really is no alignment issue... it's binding within the gearbox due to the shaft being pushed/pulled. I did find a decent supplier of aluminum couplers and the coupler that is really needed is a 3mm to 2mm coupler. Not many sell these but I found a R/C boat supplier that sells these for adapting motors (with 3mm shafts, like the Pololu motors) to 2mm prop shafts. The 2mm hole needs to be tapped to accept the 4-40 rod (a 3mm hole is too big for the 4-40 rod). The coupler you see in the last pics (new drive box) was made from one of these adapters, but was milled down a bit to fit inside the bearings as shown. Hope to get some testing done on a prototype later this weekend (too busy with real work unfort!).

    (Pic below is that of an older actuator I built... even without the thrust bearing which makes a huge difference... just posted so you can see the pivot pin details)
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    TOMAPOWA

  21. #96

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Ok folks,
    Here's a link to that build thread I started... it's a start, more will hopefully be added soon!
    I'm still messing around with actuator designs... I don't plan to sell anything before I get to ring it all out for myself.
    Feel free to post questions/comments/suggestions...

    http://www.laureanno.com/RC/E-Retracts.htm
    TOMAPOWA

  22. #97

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Here's my latest actuator design I built and tested this past weekend. Seems to work better... no binding whatsoever. More testing pending...

    Notice that the aluminum coupler is now inside the aluminum clam-shell case. A thrust bearing stops the coupler from pushing in the motor shaft while the alum case and flange bearing mounted inside the alum case stops the coupler from being pulled. The coupler is loosely connected to the motor shaft (set screw not tightened fully). This config allows the coupler to be somewhat isolated from the motor's output shaft, eliminating axial thrust on the motor shaft, hence eliminating friction caused by the output gear binding up against either gear back-plate. I'll try to take more pics of the setup this week...

    New design on left, Old design on right...

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    TOMAPOWA

  23. #98

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Nicely done so far!
    Larry

  24. #99

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts


    ORIGINAL: TOMAPOWA

    Ok folks,
    Here's a link to that build thread I started... it's a start, more will hopefully be added soon!
    I'm still messing around with actuator designs... I don't plan to sell anything before I get to ring it all out for myself.
    Feel free to post questions/comments/suggestions...

    http://www.laureanno.com/RC/E-Retracts.htm
    nice!
    Larry

  25. #100

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    RE: Electric Retracts - Modifying existing Air/Servo-operated Retracts

    Question for one of you smart guys. I'm looking for a retarct servo delay just like Doug at Ladomade. I have the Hitec 75BB 180degree retract servos and know that they they cant be slowed down so I simply just want to stagger the two.Does anyones make achip likeLADO isn't/cant/wont produce anymore? Cheap is good. :-)


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