That seems to make sense as to what is happenign to your resistor. A dented stuffing tube is placing additinal resistance on the shaft making the motor work that much harder thus in turn drawing more amps than ususal. This would loop back to the resistor where the coil would melt. I think you isolated the problem. IRCWCC NATS is July 19th to the 23rd of July. Testing on July 18th.
Interesting... Alex, I look forwards to seeing your ship this summer, I think you'd get a kick out of my "quick change stuffing tube"... Right now I should be able to swap out a stuffing tube with a new replacement in about 5 minutes
Great. I look forward to seeing your design. Are you down in California or up here in Washington? I don't think I am going to be able to make it to NATS this year.
I'm in Richland, WA. Its been a few years since I made it out to cle elum to battle with phill et al. I started there back in the summer of 2000, give or take, with a rediculously over-detailed I-boat
You could build an emitter follower ckt. and place the heavy duty transistor through the hull so it could be water cooled. I did this for a cargo ship once and could adjust the speed with a simple variable resistor to the base.
I am up in Bothell, Wa. Just north of Seattle. Are you the Greg that is building the Tirpitz? I was talking to Phill and he was telling me about it. I look forward to seeing that too.
We are hoping to talk Greg into showing up this summer. It helps to have a working ship. With a bit of luck we will see more ships on the water this year.
So, I have just bought a ESC. I am sick of having my ship in dry dock but at the same time I dont want to put the ESC in untill I figure out the problem with the resistor. I bought another resistor, the same kind that I had before. I would rather burn out a $5-8 resistor rather than a $70 ESC. Is this good thining or should I just put the ESC in and hope for the best. My current theory is that the stuffing tube was putting to much tension on the shaft which in turn was putting in on the motor. I have fixed that so the shaft spins much better now. Should I just put the ESC in or continue with my plan? I think part of it is that I am kind of old fasion and I am used to the old swampy resistors and I dont know a lot about the ESCs.
Ok, the short and skinny of it is as follows. Follow the esc instructions, if you suspect a drag issue, but think you have solved it (as an aside, are you using a brass driveshaft and brass bushings/stuffing tubes?) plug in the ESC, and get one of the clamp on current meters from home depot (they clamp around a cable, they do not interrupt the circuit). start at very low throttle, watching the current using the meter.. if the current goes up too much, cut the throttle, you still have a problem. That will tell you if you have a current problem without destroying anything or over-currenting anything the other thing to consider is that if the motor's brushes are corroded/the bushings in the motor are worn out, it may also be a motor issue.
It is a steel shaft with brass bushings/stuffing tubes. Current is rated in amps, correct? Also, since you have the same kit do you know what the drive motor is rated for? I dont think its a motor problem, its brand new and never been underwater.
If you have a brushed 550 class motor, it should be pulling less than ~10A unless stalled, which can, depending on the model, exceed 85 amps. Some of the motors I used to get, years ago, had 100A listed as stall current at the operating voltage. they burn up rather quickly when you stall them, if you don't fix the stall. I do not run the standard motors any longer, generally because I like to do things differently and I feel that brushed motors are a technological dead end, at this point, especially considering all the inexpensive Chinese brushless motors out there... that being said, it can be difficult to find the right brushless motor & gearing, since we do not have a long history of using them and hence do not have a large knowledge base of folks where one can just go and say"I'll use that setup, it will work.l
Where would be a good place to put the ESC? Outside the radio box or just replace it with the old throttle servo? Also, what are those little things you put on the motors to eliminate noise interference?
First question: Is your ESC waterproof? if you bought one of the MTroniks ones, then just put it outside the waterproof box near the motor. The things put on the motor are capacitors, generally in the .47 micro-farad range, if I recall correctly.
Generally, I try to minimize the distance from the esc to the motor, and I also try to keep the servo leads under ~18 inches. IF you have noise issues (electrical noise that is), one can deal with that readily (usually) by wrapping the servo lead around a ferrite ring. One question, how are you powering the receiver? if you are not using the internal BEC in the speed control, you MUST remove the red (positive) lead from the connector connecting the receiver and the ESC, leaving only black (ground) and signal.
Have you read the article [b]ESCs Lessons Learned on the NTXBG.org knowledgebase? STRONGLY suggested reading for someone new to ESCs. For instance should you or should you not clip the red wire - guessing wrong can fry your ESC. Cap the motors? You bet your bippy you should. Lots of other things. Save yourself a very expensive learning curve - read, and understand, the article (and the EXC's manual) before proceeding.
