Motor info wanted

This topic is empty.

Viewing 13 posts - 1 through 13 (of 13 total)

Author

Posts
13 July 2016 at 16:33 #66516
Kev.W
Participant
@kev-w
Have been given a motor & would like to know what it is & what performance I would get from it.

I know it's a Johnson & have run it on the bench with ammeter in line, so I know that at 12v it draws 2amp when free running. It is 60mm long 36mm dia. with 3 poles.

Could anyone advise on type, revs, min/max prop sizes & likely current draw please.

Edited By Kip Woods on 13/07/2016 16:35:28
Advert

13 July 2016 at 16:33 #4338
Kev.W
Participant
@kev-w
13 July 2016 at 18:59 #66521
Dave Milbourn
Participant
@davemilbourn48782
Kip

At 2A with no load at 12v it's almost certainly a screamer. Odds are it's a 540/550 3-pole motor and may not even be rated up to 12v (many are rated only up to 7.2v). If you want to put it into something like a Club 500 then you might get away with 7.2v and a 30mm 2-blade prop. If your plan is to use it in a tug then I would say don't!

Caveat: This is only my opinion and is based on nothing other Kip's description and my 45 years of operating small DC electric motors. Apparently the epithet "expert" can now be subject to intense query and debate by anyone – see Mayhem. **LINK**

Reassuring and inspiring, isn't it? Suit yourselves.

DM
13 July 2016 at 20:52 #66522
Kev.W
Participant
@kev-w
Thanks Dave, it came out of a 12v drill, so is definitely rated at such, it had a planetary gear set up on it, but I stripped that off with the chuck.

I'm saving it for a future build, nothing too complicated, so would it be ok in something like a 'Broads' cruiser of about 2' 6" in length ply on frame ?

Or am I thinking too big a boat.

P.S. I looked at the 'link' & I say that as a complete numbnuts when it comes to modelling skills, I am slowly improving & now doing things I never thought I would be able to, this is down to reading this & Mayhem forums, the amount of advice & tips on how to do stuff keeps me learning & interested.

Keep up the good work & don't let the bu**ers grind you down.

Edited By Kip Woods on 13/07/2016 21:18:43
13 July 2016 at 23:08 #66523
Dave Milbourn
Participant
@davemilbourn48782
Kip

It was designed to be operated with a gearbox and in my opinion that's really the only way to use it. Brushed motors of that size are so cheap that you might as well buy one that better suits the model you are building.

If it were mine I would save that particular one for ballast, but I don't have an "Expert" certificate or T-Shirt so you're not obliged to take any notice of me.

Thanks for your support anyway.

DM
13 July 2016 at 23:12 #66524
Charles Oates
Participant
@charlesoates31738
Hi Kip, as Dave said, it's probably suitable for a club 500 type boat. That's a type of racing boat, goes fast etc. Your Broads cruiser is ( I presume) a sedate displacement model, not ideal for high speeds. Forget this motor for that model. Save it for something in the future.

When you need to source a motor for your model, post again with some details. I hope the build goes well, glad you like the forum.

Chas

Sorry Dave, we both posted at the same time.

Edited By Charles Oates on 13/07/2016 23:14:21
14 July 2016 at 09:19 #66530
ashley needham
Participant
@ashleyneedham69188
DM. You need a disclaimer, like mine !

Just had a read of the mayhem posting, and if you take it to heart you would a) never volunteer advice and b) never give it ! I (usually) only suggest things* and this can be taken on board or ignored as suits..

With the motor in question, getting back to the thread, it is an unknown quantity * and not worth using *, as DM says, brushed motors are cheap* and you can get something absolutely suited to the boat * you are making and it will be perfect *.

What are the stars for?? well they are disclaimers, they indicate an opinion based on someone's knowledge/experience, and how many there are for such a simple sentence! For the picky person, a field day eh?

I have a clutch of "unknown quantity" *motors in the box, and I should really just bin them*, but then contrary to the stated advice I think "but may come in useful at some time" and put them back.

Ashley, Expert (usual disclaimer applies)
14 July 2016 at 11:52 #66537
Kev.W
Participant
@kev-w
Thanks guys, will ditch it as a 'considered option', but I hate chucking stuff away so will do an 'Ashley' & chuck it in my junk box ………………………… well, you never know do you.
14 July 2016 at 12:39 #66540
Ray Wood 3
Participant
@raywood3
Hi Kip

It would be shame put it in the junk box, If you run it on less volts say 6v with a speed controller I'm sure it would be sedate enough for Broads type cruiser ?

Regards Ray
14 July 2016 at 14:49 #66546
Charles Oates
Participant
@charlesoates31738
Hi Ray and Kip, just to put a bit more meat on this. Like many others I have a box of similar old motors. I tried one last summer in Cynette a 30 inch fast displacement cruiser from the 1950s. On 6 volts it was over powered and amp hungry. It was replaced with a 550 motor, plenty of speed and very tractable, able to swing a decent prop so it doesn't slow much in the turns.

The only success I've had with an ex drill motor is one I re wound just for the hell of it and because I'm weird like that.

As Dave says, I'm no expert, but after making boats for 50 years I've made more mistakes than most, and I still am. I glued myself to the soxxxng boat this morning, ruined the paint, my finger, and my wife is still laughing.

Chas
15 July 2016 at 15:52 #66567
BRYAN ASTON
Participant
@bryanaston57723
Kip

I have used black and decker johnston motors in all sorts of boats including 36 inch cruisers I have had no problems at all, just use it ,don't complicate things, keep life simple

Bryan
15 July 2016 at 21:26 #66572
Kev.W
Participant
@kev-w
After what Dave said about 7.2v, I stuck it on a 6v nimh pack, it still draws 2 ah but did seem happier to rotate at a less of a scream (and it did scream loudly on 12v)

The next build is still a long way off, plus I still haven't decided what I want to build yet, was more interested in what type of motor it was.

My other thoughts are how reliable it might be, I don't know how many hours it has run or how it was treated, not the best start for a boats life.

Still it may just find it's way into some madcap fun boat one day.
15 July 2016 at 21:45 #66574
Kev.W
Participant
@kev-w
This is the last fun boat I made, it was for a club competition in 'straight line running', you had power control, but were not allowed to steer, it was case of judge current & wind, point at bouys and go.

It's just a flat piece of wood 2ft long x 2.5" wide x 12mm thick, it has a shallow fin on the bottom for directional purposes, but no rudder.

Don't know where I got the motor (it was in my junk box) but it did an admirable job until it capsized.
Author

Posts