TOMAPOWA

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LOL....
Wish I had a friend that does CNC'ing... I'd certainly like to sell some kits for ther DIY'ers.
Yeh, those robostruts are not just exceptionally strong, but cool (& scale) looking too! Worth every penny!

The Robarts I have were easy to mod, simply unscrewed the air cylinder's rod from the "T" control bar (lets call it... don't know a better name for it) on the retracts and luckily enough, it was already tapped for 4-40! I simply assembled by gear motor with coupler and 4-40 threaded rod (shown in pic oin video) and threaded this rod onto the "T" control bar (had to clean it out first as it had a little loc-tite on it... due how the original air cylinder rod was attached). The back-end of the gear motor assembly is then attached to the existing pivoting rod on the backend of the retracts using the same original pin and c-clip. Literally took 3-minutes to mod...

I just found out today (Happy Thanksgiving btw!) that my sample chip (one I plan to use to control motors and sense stall currents) just got shipped... gheeeezz...

I'm also looking at this to start a prototype of the electronics... interface this breakout board (uses same chip as what I ordered) to a PIC and I should be in business...
http://www.pololu.com/catalog/product/712

warks62

My Feedback: (140)

I am sure that there are many that can do this for you Tomopowa and I really like the idea of current sensing. Here is a company that looks like to me that might be able to design what is needed. Tomapowa great work and great ideas. Here is one more idea for you that Doug never did. If you have electric retracts then electric cylinders need to be made for gear doors and such so that the entire system could be electric instead of a mix between the two. Also this is just a guess but I don't think that Doug has the financial backing that is needed for his company and that is why he is having such a hard time. That is a bit off topic but what I was getting at is help from a well known company is not a bad idea. Anyway here is the link.

Looks like while I was typing you figured it out and had a post great work....

http://www.thomson-automation.com/

TOMAPOWA

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Hey thanks Randy....
Great idea with the actuators for gear doors and such... I had in fact thought of that and if possible, these functions (staggering of doors and gear retracts) could be built into the control board w/ user-adjustable settings. I'm pretty well versed on the electronics side of things... it's really the mechanical side I dabble in. I hope to worlk some of the electronics this coming week when parts come in... as for the actuator assembly, I'm still pondering a few ideas. I can't beleive there are no CNC ppl out there who are willing to help!

Don't force me to purchase a milling machine now... !

Larry3215

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Oh no! I think that was Dougs first excuse

warks62

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Glad the electronics is your thing. That will help a bunch. As far as the mechanical side to me that is where help from a company comes in. You have all the parts made in larger quanities for you so that all that is left is assembly. I have a friend that has product made in China in large quanities but he doesn't trust them to assemble. He does that here so that quality can be checked and mantained and as they are being assembled. Another plus for you is almost all the retract manufactuers use very few different size cylinders so you won't have to make that many different setups.

I like your idea of a single contoller for motors (retracts) and gear door operation kind of a all in one.

I just wanted to tell you why I like your idea on this. I really have nothing against air it has worked for me for years with no problem and for the last couple of years I have used the Tamjets air failsafe device which is really cool in case of a airleak. But, in a scale plane with your setup the gear will always move at the same speed and could have stagger dialed in making for a really scale retracting setup. This would give the same scale look everytime, something that I have not been able to do with air. Sometimes they just move easier or at different speed maybe because of temp I don't know. Your setup would be really cool. One more idea for you would be to sell kits and let the end buyer put it together, just a idea. I will be following your progress with great interest.

TOMAPOWA

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Latest Development!
Finally got some electronics working..... incredible how well they work!
These will soon be going back into my 1/4 Scale japanese A6M5 Zero.

[youtube]http://www.youtube.com/watch?v=s-SXHH1qXwg[/youtube]

Larry3215

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That is absolutely awesome!!

flemsus

Bingo. Now I need it in a smaller retract please.

TOMAPOWA

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Curious,... what brand/size/model retracts are you looking to modify?

jim pettis

Those do look really good. I would be looking to fit a set into the Hangar 9 Spitfire (.60 size)

At this point however, you are just retro fitting a robart air strut correct? I know you are hoping to get someone involved with the CNC part of these, but at this point it would mean having to buy the air struts and drop your equipment into them?

Great job so far. Hope this ends up going somewhere, as there certainly is a market for a well supplied retract like these.

Keep us up to date!

flemsus

.60 size, I am one of the " Where is my Lado" guy's

warks62

My Feedback: (140)

TOMAPOWA, it looks great was wondering are you going to sell kits or instructions? Seems to me that once you have the controller then you would only need to change the size of the motor to fit the retract that you want to install it in? Maybe I missed it but what did you use to connect the screw shaft to the motor? Thanks great work.

TOMAPOWA

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Hi Jim,
Thanks.... and yes, I am currently only looking at designing some retro-kits for modifying existing retract units. I only own Robart so I know the design will work with those. I wish I owned a few other types to see if these actuators would work with them too. I know the retract models made by AirPowerNet.com would work too.... a friend has a few sets. Just as long as the trunion used in the retract mechanism is split on both ends, it should work (needs to be split on both ends so the threaded rod can go straight through the top portion of the trunion, allowing the jack-screw-like actuator to work properly). And since this design uses a 4-40 threaded rod, the hole in the T-control bar (one that pushes/pulls trunion) needs to be tapped for a 4-40 threaded rod (all the ones I mod'd were in fact 4-40... lucky me!)

I have not gotten any commitments from any Co./person yet in regards to design/manufacturing... seems like they might already been looking at designing something... and if any of my notes can help, I guess that's a good thing. The ultimate goal of mine would be to have someone manufacture the actuators (motor/gear-box, case, wire, etc...) of full retracts with motors, and I would supply the electronic smarts!

Once I prove out the design and s/w, I might sell some DIY kits that would include the gearmotor, bearings, coupler, motor holder (two bent pcs of aluminum w/ screws), and of course the controlling electronics.

I also modified a set I use on my 60 size CMPro Spitfire... originally it was using a cheap set of Hobbico retracts that were originally designed to use a servo to actuate the retracts.... my first video shows this design (uses same gear motor assembly and same electronics... it simply bolts onto exsiting screws on the retracts. I'll try to take a few pics of those and post them.

One area I'm still working on is the need for a thrust bearing as most of the push/pull forces are on the motor shaft... and will eventually wear something out. The model you see in the latest video has a ball-bearing in place behind the coupler which eliminates most of the force (push) on the motor when bringing the gear up. When bringing the gear down, there is little force (pull) on the motor as gravity is doing most of the job. Doug @ Lado mentioned in one of his posts that he was having problems with bearings he was using... they appear to be seizing/breaking... maybe this bearing is being used for the same purpose I plan to use it for, therefore some testing will need to take place for me to be confident with the design.

One last thing I need to mention is mostly a recommendation.... With most electric retracts, I would design them to be powered off of a seperate battery (say a small 2000maH 2-cell LiPo) instead of them getting their power from the receiver (like Lado's design). stealing power from the receiver could be a bad idea especially if the gear hangs up and draws excessive current from your receiver battery. Imagine your gear failing and it pulls so much current from your Rx battery, that your receiver reboots while in-flight (like the case of some Spektrum receivers). I feel better in powering up the electric retracts from a seperate battery/source (or as in my case since I fly large electrics, I plan to use a seperate 10A regulator connected to my main 12s packs). If I owned Lado retracts, I'd really be concerned about this...

Do any of you fellas actually own Lado retract?... and if so, has anyone ever taken it apart to see how it works? I'm certain he is using a similar stall method in detecting end-points (full up/down positions), vice limit switches, etc...

TOMAPOWA

My Feedback: (1)

Hi Randy,
We'll have to see about DIY kits... I like the electronics portion, the mechanical portion can be a pain though.
I use a custom-machined aluminum coupler, one side attaches to the "D" shaped motor shaft (via set screw) while the other end is threaded to accept the stainless-steel 4-40 threaded rod, using red loc-tite of course! (I think Lado was using a brass looking threaded rod.... not a good idea as it will wear over time... cheaper I guess... but I'm looking for high reliability, not cutting costs). I'm also using a 3mm ID bearing to take up some of the thrust put onto the motor shaft... without this bearing, it will wreak havoc with the gears and brass backing-plates in the gear-box (don't ask me how I know this... [8D]).

kodi7

Hi TOMAPOWA,

I have read with interest your conversion from air to electric retracts. If you want, send me an email and I will discuss making the aluminum couplers.

[email protected]

warks62

My Feedback: (140)

TOMAPOWA, maybe there is a off the shelf motor that you could get that is designed to take thrust loads so it would be a lot less work in the long run. Just something to think about. Also have you seen a motor that has a hollow threaded shaft. Something that I was thinking about for gear door operation. Threaded rod with ball link at one end that threaded into a motor. Nuts on the threaded shaft before and after the motor would be the end stops.

jim pettis

Looking at mine, it appears that he riveted a circuit board across the two halves of the retract body, so I'm guessing that opening it up to see how it works equals never seeing it work again. If they were plentiful I would be tempted to send you one to open up. However, as you are aware....Doug is pretty much shut down at this point.

Depending on what you end up with for parts pricing, it may be worth it to purchase the air retracts and use your system to retro fit. Always nice to have SOME options out there.

Larry3215

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The circuit board can be removed with no issues. Its held on with screws. I did so several times while modding mine for nose steering.

Your setup is virtually identical to Dougs. Geared motor driving a 4-40 threaded rod which drives the trunion.

GMTA

TOMAPOWA

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Thanks Jim... by no means ruin by disassembling. From the pic I saw, I thought the PCB was attached with pan-head hex screws vice rivets. Wonder how you do repairs then...??? Out of curiosity, have you operated the Lado and if so, can you tell me what happens when the actuator reaches both limits? Does it sound like it binds a little or does it just stop short of any obvious binding, as if limit switches were being used).... again, just curious (hope I did not let my stall-current measuring idea out of the bag.... don't want Doug to steal my ideas... then again, he almost stole my $$ so his reputation is pretty low in my eyes).

Randy, great idea... do you know any manufacturer of these type of hollow-threaded-shaft motors? To operate properly, they also need to operate at roughly 500-600 rpm (~10 revs per second, i.e. most likely geared) such that it spins the 4-40 rod at the appropriate rate for that scale realism.

Larry3215

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There is a slight binding at each end of the travel range and a corresponding current peak.

TOMAPOWA

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Ah...as I thought... Thanks! It would not make sense to incorporate limit switches, etc... way too complicated.
With retract retrofit actuators like mine, you really can not use limit switches as this "limit" (i.e. actuator throw) as the stall current would vary from retract to retract. One function I plan to mess with tonight is a stall-learning feature where every time you power up the gear, it learns/memorizes the stall current for both directions (full up/down). This is important because this stall current could (and probably would) be different from retract to retract, and, over time after flying, this stall condition might change (i.e. retract start binding, lack or lube, etc...). So much to consider...

TOMAPOWA

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Larry... just noticed your post (must had missed it some how...)
When you had the unit apart, did you happen to take any pictures? Did you remember seeing the motor... and if so, did it look like the gear motors I am using? Also, did you happen to see any bearings? If so, where were they? Any info appreciated...

Dan M

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It cracks me up that you are asking other People to take apart their Lado retracts so you can use Lado's Research and development time and his ideas to come up with your own line of retracts and market them .

it's very strange to me that after you posted on the Lado thread so prolifically , and did all that Doug bashing , that you don't even own a pair of Lado's to Backwards engineer ??

ROFLMAO !

Maybe he will still sell you a pair ?

TOMAPOWA

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LOL... actually, I'm learning from his mistakes/bad design!
I knew it'd only be time before the riff-raff made rediculous comments... like yours!
If you are really enjoying your Lado retracts, go and Enjoy!... no use being part of this discussion... Bye now!

warks62

My Feedback: (140)

TOMAPOWA, I have seen hollow shaft motors but not gear box's was hoping that you had. Have to look around the Robot guys just seems like something they would have. It is the only thing I have come up with for gear doors except for a double bell crank with a rod connecting both bell cranks at one end. The rod would be threaded in the middle and then the other ends of the bell cranks attached to the doors. Then have one of your motor setups with the jack screw threaded onto the rod, you could use nuts to limit travel. I have done something similar but with a air cylinder. Don't want your mind going idle.