Need explanation- electronics to operate screw drive

[JDH429]

Just joined up and am full of questions which i cant seem to find a clear explanation on. Im planning and still gathering for a dump trailer project which will utilize a screw drive. I think i have the moving parts figured out but am unclear how the electronics will work. Im pretty new when it comes to this part.
I recently put in a huge order with Garden Trucking and emailed them about how i can set up the gear motor to operate using end points. Ric replied "Use # 295s it has limit switchs" and gave this diagram.



They have usually been pretty short in emails in my experience and figured they wouldnt have the time on the phone either for "new" questions so..

-Is this what you need to use to operate a gear motor for a screw drive?

Ive searched and found nothing that explains how the radio operates...

-What type esc(BEC) or escs are needed (more than 1?). How do you run two escs on one RX...AND what radio is used?

-Is a 4 channel rx/tx used and one stick is used for forward and reverse motor operation? or is a toggle switch wired into the transmitter (no clue how to do that)?

I think i want to use this motor because ive read that you want at least 50 rpm if using a fine pitched threaded rod for the screw. (was planning on 1/4 28 threaded rod)
http://www.servocity.com/html/81_rpm_gear_motor.html

but this motor operates on 12 v and im not running 12 volts in my tractor...or am I? Oh man...its enough to lose sleep over. Then what batteries...?

Need big help as you can see. Thanks for looking to anyone who thinks they have the time.... and, "To put something in layman's terms is to describe a complex or technical issue using words and terms that the average individual has no freakin clue about"... Yes! exactly.

[dabears]

See if this helps. you could use an esc to run it of 1 channel of your radio.
http://rctruckandconstruction.com/sh...ht=screw+drive

[Espeefan]

JD, what you have there is an ESC (electronic speed controller) diagram, with some built in inputs for limit switches. Item 295 is the ESC that Ric recommended to you. You will use this one to run your screw drive, if you so choose. Your limit switch inputs are necessary because you'll want something to stop the motor running the screw drive, so it doesn't over travel at the top, and bottom, of it's stroke.

If you purchased a radio, it will come with a manaul, so most of your questions regarding the radio and receiver will be answered there, however to quickly answer your questions, radios have separate channels for each function. Steering and throttle are two separate channels. The screw drive will be another. On some radios, you can assign a toggle switch, knob, or stick to any channel you so desire, but this is a feature that usually comes with the more expensive, programmable radios. Most 4 channel radios do not have this feature. Your manual will tell you what channels are for what stick, knob, toggle switch, ect. You just need to figure out what you'd like to use. With that said, you'll be able to run the screw drive ESC with a toggle switch, or a stick. Which ever you choose. But be aware that a toggle switch will be either on, or off. A stick will give you proportional control. Slow to fast, and anything in between, depending how much you push the stick. It's up to you to decide if you want proportional speed control of the screw drive. It's personal preferance, but I think it would be fine with a toggle switch.

You asked about a BEC - a BEC is battery eliminator circuitry. Basically the radio receiver needs power to run. The receiver can be powered by it's own dedicated battery, or it can get it's power from an ESC, which has internal BEC. With the internal BEC, the receiver does not need an extra battery pack for itself. It draws power off the battery pack that runs the model. Hence the term BEC. Do you need a BEC? Most all ESCs come with some form of internal BEC, so the short answer is no, you don't need a BEC, if you have an ESC featuring that. There are exceptions to the rule. There comes a point where if you are running a lot of servos off the ESC's internal BEC, it may not be able to provide the current the servos are asking for. In this case you would want to get an external BEC. An external BEC is just a separate stand alone device which drops the main battery pack power down from a high voltage, to something less, so your servos don't get over volted (fried). For a semi truck that has one steering servo, and one shifting servo, you probably won't need an external BEC. The ESC should be able to handle that.

If you want to run two different ESCs on one receiver, you just plug each ESC into it's own separate receiver channel port. Easy. One ESC will run your truck's drive motor, and the other ESC will run the screw drive, for the dump box/trailer. The receiver will run each ESC separately, based on what you are doing with the controls. Again, this will be explained in your radio manual.

As for your choice in the screw drive motor, I can't offer much advice with that. I've never built a screw drive, so I can't help you pick out a good RPM motor. I am sure some others will chime in with advice. I will say you can run a 12 volt motor on less voltage, but you then need to account for a decrease in it's RPM.

Battery packs - you can run whatever you feel like. 7.2 to 12 volts is pretty common. I think it's more common to see 7.2 volt battery packs with the Tamiya trucks. Feel free to run either, but it's nice to stick with a readily available 6 cell, 7.2 volt pack, as they are cheap, and available everywhere. Not so with 10 cell, 12 volt packs. I know none of the hobby shops in my area stock them. You can get them online though, easily enough. My advice is to stick to the most common battery pack types. Either NiMh 6 cell packs (7.2 volts) or LiPo 2S packs (7.4 volts). Battery discussion could be a whole topic in itself, so for now we'll keep it short and simple.

Hope this helps.

[JDH429]

Dabears, thanks for the link. Im pretty familar with that thread as its what i find everytime i search for "gear drive". Its what explained to me how the mechanics work. great resource.

SPfan, Thanks for that lengthy explanation. So it makes sense now that you can run multiple esc to control multiple motors from one rx. I never thought that....So does this mean i need to run separate batteries as well? or can one be used with a Y to power both? I have not purchased a radio for this project yet so i can go either way. I guess a stick would be nice to control speed like you mentioned. The esc that Ric sells comes with actual physical limit switchs? or is this something internal in the esc? not sure if you have used one of these #295 before. Id like to know what others who have built their own screw drive have used..whats the preferred setup.

Oz, im unfamiliar with a dpdt switch. ill have to google that one. Thanks for the diagram. What is the function of the diodes? Thanks, this helps alot.

Im sure this type of work is common for the people who have the experience with RC and especially for the guys building complex machines such as mult axis construction vehicles. Takes a lot of engineering to plan such projects. My hats off to them. Its a new avenue for me so excuse my ignorance. I hope more will chime in to talk about their set up and why they like, or dislike. I did not find too much info on this area. Maybe this thread will help others later on who have the same questions.
Please keep this going, i can use more help as always.

[Espeefan]

Originally Posted by JDH429

SPfan, Thanks for that lengthy explanation. So it makes sense now that you can run multiple esc to control multiple motors from one rx. I never thought that....So does this mean i need to run separate batteries as well? or can one be used with a Y to power both? I have not purchased a radio for this project yet so i can go either way. I guess a stick would be nice to control speed like you mentioned. The esc that Ric sells comes with actual physical limit switchs? or is this something internal in the esc? not sure if you have used one of these #295 before. Id like to know what others who have built their own screw drive have used..whats the preferred setup.

JD, you're welcome. If you so choose, you can run one battery pack on a model, and have multiple ESCs getting their power from it. You simply need to wire the ESCs in parallel, off the single battery pack, with a y-type harness.

The ESC #295, which Ric sells, I haven't actually owned myself. I don't know if it comes with the limit switches or not, but I would assume it probably doesn't. You would have to contact Ric to be sure.

Ric gets a ton of emails every day, so don't feel offended by his short replies. He is a one man operation, plus I think he has one helper, but he has to weed through a lot of emails, some of which come from people who are just tire kickers. Best bet is to call him up. He's a good guy to talk to, on the phone. Always happy to answer questions and explain things. He and I have talked at great lengths about trucks, and projects. He's just like you or I. Very easy to get along with. I'd give him a call. It helps give you a quick answer, rather then waiting for a return email, and a phone call lets him know you are serious, and not just kicking tires.

[JDH429]

Ahh, excellent point. I didnt really know too much about the operation over there other than my experience from making a couple purchases online. Thank you again for your help.

[JDH429]

http://www.rctruckandconstruction.co...ead.php?t=3997

just found this thread. The relay suggested is no longer sold. wondering if anyone uses something similar since then. thx

[WhiteWolf McBride]

JD:

One critical thing if using one Rx (receiver), multiple ESCs (electronic speed controls), and any number of batteries:

Most if not all ESC's contain a BEC (battery eliminator circuit) so you don't need to run a Rx battery, right? This means the battery that supplies your main power (drive motor, and all accessories like lights, sounds, etc.) also supplies the Rx, right? So, you DONT use an Rx battery pack.

Some guys want to so they don't loose control of their model when the battery goes below about 5v, and the Rx cuts out. They plug it in, and watch their ESC and/or their Rx smoke. WHY? Because the BEC in the ESC is supplying voltage as well. They conflict, and poof, your Magic Smoke is loose!

That extra wire (usually red) in the three that go from the ESC to the Rx (black is ground, the other is the signal). You want to unplug this wire's plug from the connector, and then put a bit of insulation over it. Some cut the wire, but its a pain to patch it later. Now the ESC is not supplying power from the main 7.2 pack.

Now, multiple ESC's... you need to do this trick on all but one of them, or they ALL try to supply the Rx with power, and you end up with loose Magic Smoke again (or ALL of them if you want to run a separate Rx supply.

Make sense?

And yes, you CAN use multiple 7.2 packs connected with a Y-connector, just be sure its a Parallel type connector, so you are adding the amperage, NOT a Series connector, and end up with 14.4 volts.

That make sense too?

WhiteWolf
- with a tip from the tankers.

[fhhhstix]

Originally Posted by JDH429

http://www.rctruckandconstruction.co...ead.php?t=3997

just found this thread. The relay suggested is no longer sold. wondering if anyone uses something similar since then. thx

Here is a new link to the same relay switch. They are now sold exclusively by Servocity. You will need a servo lead, wiring to the motor, wiring to the battery, wiring and limit switches. So soldering is required for this controller. This is the best controller I have found and used for a screw drive and I use it for all of my screw drives

Click here for the motor controller.


Travis

[JDH429]

Travis, thanks so much. Do you use Servocity;s gear motors as well too? what rpm motor you like? I have read your other threads on your gear drives and appreciate them very much.

yes i had emailed these guys (servocity)about how to use this and i was sorta lost when reading the reply"I have provided the data sheet for the PWM controlled relay that you inquired about. The jumper pin will set your thresholds."
I dont think i can post a pdf otherwise id show you the data sheet but im sure you already have it if your using these. Do you think you can write a "how to" or draw some sort of drawing on your setup if you have time? id really appreciate it. thanks so much for the help.

[JDH429]

Originally Posted by oztruck

The diodes will stop electricity flowing in one direction but allow it to flow in the opposite direction. When it reaches the limiting switch the switch cuts power to the motor, to get it to work in the opposite direction, to go the other way we need to supply power. That's what the diode does. It lets the reverse power ONLY to reach the motor. Hope this helps you.

that makes sense. Are the diodes special for this application? i mean if i needed to order these from somewhere..what do i ask for exactly? thank you

[fhhhstix]

Originally Posted by JDH429

Travis, thanks so much. Do you use Servocity;s gear motors as well too? what rpm motor you like? I have read your other threads on your gear drives and appreciate them very much.

yes i had emailed these guys (servocity)about how to use this and i was sorta lost when reading the reply"I have provided the data sheet for the PWM controlled relay that you inquired about. The jumper pin will set your thresholds."
I dont think i can post a pdf otherwise id show you the data sheet but im sure you already have it if your using these. Do you think you can write a "how to" or draw some sort of drawing on your setup if you have time? id really appreciate it. thanks so much for the help.

I use the Carson gear motor that they use for their spindle drive Link to motor.


Here is a pic of the setups you can use. You would be using the linear actuator set up and your screw drive will be the actuator. The jumper they talk about is the little green square on the board. It either connects the two wires when the jumper is installed or disconnects them when removed. This adjust how much throw of the stick on the radio it takes to activate the switch (thresholds).





This is by far the simplest way to do what you want and it is a solid state compact unit.

Travis

[JDH429]

Thats excellent. Do you use the limit switches? Can they be purchased from Servo city as well? Do i need a particular limit switch? I couldnt tell from your thread showing your screw drive. Do you happen to have a picture you can post of a top view to see the limit switches inside the rails? Have you ever considered the #295 from Ric? just curious. Thanks again, really appreciate it.

[fhhhstix]

Here are the limit switches I use since my local hobby shop caries them. Tower Hobbies also caries the switches.

Limit switch

No pics of them installed. They just need to come in contact with the slider block at each end of the screw drive.

I am very happy with this controller and it has been very reliable with no issues. So I really have no reason to try some thing else.

Travis

[JDH429]

Great, youve been a tremendous help and so has everyone else. I think i fully understand what i need to do. Thank you!