Topic: MFA geared motors (Read 10191 times)

portside II · « **on:** June 04, 2008, 11:02:10 pm »

right not been having much luck with the 555s in the Dutch River as they are under powered and i tried a pair of johnsons and all they did was melt fuses .
so after a word from Jackie at Model Slipway i was advised to go for a geared motor about 6:1 .
Now there are a couple i am looking at from Maplin ,
http://www.maplin.co.uk/module.aspx?ModuleNo=43373&doy=4m6
http://www.maplin.co.uk/module.aspx?ModuleNo=43368&doy=4m6
Both of these are the same price but the first is more powerfull ie, 5 poll against 3 poll, are they any good or can someone recomend anything else within the same price band as i would require twoand the postage is free from Maplin ,also are they reasonably quiet.
daz

ray123 · « **Reply #1 on:** June 05, 2008, 07:36:02 am »

hi portside II the motors i use in all my models are robbe 'navys' (orange gearbox) thay are a geared 540 -- 5:1 on 12volt & 3:1 on 6volt cost approx £24 each (westbourne model centre)
regards ray

portside II · « **Reply #2 on:** June 05, 2008, 08:09:07 am »

thanks Ray ,the price is not too far off and i am off to Bournemouth for a few days next week and intend to visit westbourne's just in case the wife wants to buy me a new kit

.
Are they reasonably quiet as i cant stand grinding gears , but thats just me.
daz

funtimefrankie · « **Reply #3 on:** June 05, 2008, 07:11:58 pm »

I have one with the red gearbox, it's so noisey I didn't fit it, make me an offer

ray123 · « **Reply #4 on:** June 05, 2008, 09:29:03 pm »

hi guys at first mine were noisey i put some grease on the gears & gave it chance to run in & dont tighten the 2 grub screws up 2 tight!! now thay are fine regards ray111

Subculture · « **Reply #5 on:** June 05, 2008, 10:02:34 pm »

What's the size and pitch of the prop(s).

Graupner 720 is a good motor for a larger model, and will turn larger props direct drive (upto 2.5").

The other option is to use a toothed belt drive, silent and efficient, but more expensive than a gearbox.

Other options are the mobile marine motor range, car blower motors or surplus Buehler, maxon, Pittmans etc.

Andy

portside II · « **Reply #6 on:** June 06, 2008, 12:55:41 am »

Cheers Frankie ,i will bear that motor in mind as i am after two if i need an odd one your the man.
Andy ,the toothed pully drive was an option as i did have a pair of speed 800s with reductions (pully;s and belts) but sold them at the time they were cluttering and a friend at the club was after them ,the price was right.
Space is an issue in the tug and i have fitted the mounts so a geared motor will go right in without any major problems also the MMM motors are more than i would like to spend .
daz

Subculture · « **Reply #7 on:** June 06, 2008, 10:35:02 am »

How about a pair of these-

http://www.distel.co.uk/asps/details1.asp?ID=NQ34

justboatonic · « **Reply #8 on:** June 10, 2008, 08:53:49 pm »

The MFA geared motors do sound a bit 'boomie' especially in a GF hull. Still, I suppose they could be thought of as a couple of old diesels from a distance!

portside II · « **Reply #9 on:** June 11, 2008, 09:50:45 pm »

Happy bunny now ,PAID ££ a visit to westbourns today and bought a couple of 6:1 reduction MFA motors,and whilst i was there and the wife browsing outside i also bought a pair of 3 blade 70mm props for a future project and a 3 blade 65mm for the barge ,so thats me over £60 lighter and the wife none the wiser ,as she was told that i had not spent as much as a pair of shoes

.
daz

portside II · « **Reply #10 on:** June 21, 2008, 08:21:42 pm »

:'( not so happy now :'(
fitted the new geared 6:1 motors and even though the weather was damp i decided to give them a test .first impressions ??? a bit flat ,so out of the water and a tweek of the esc (electronise speed etc) turned up to full and back into the water :'( a little bit better but still flat ,looks like the 6:1 reduction may be too much and there is not enough speed on the props ,i am running on 12v same as before with the direct drives .
On the good side i am not blowing the fuses .
any ideas please.
daz

Shipmate60 · « **Reply #11 on:** June 21, 2008, 08:38:49 pm »

Tell Barry about it and get the parts to make it a 3:1 gearbox, should be the cheapest option and you can turn the ESC down if too fast.
According to their website the 6:1 gearbox only gives 1900 rpm on 12 volts.
The 2.5:1 gives 3800 at 6 volts, so twice the speed.

Bob

portside II · « **Reply #12 on:** June 22, 2008, 04:23:00 pm »

Sorry Bob ,who is Barry.
I have replaced the fr15 electronise esc with a mtronics 25 and will try it again ,in the water the problem was that the props were not turning fast enough to power the boat there was hardly any water turbulance behind the boat .When i bought the motors the other option was the 3:1's but i only went on what was recomended , also i am only using one 12v 7ah bat and the motors are wired together + - / - + to give the correct rotation dont know if this matters one other option is to go with 2 12v bats and twin esc , oh so many choices .
Oo is Barry the bloke at Westbournes ,(brain warming up now) .
daz

Shipmate60 · « **Reply #13 on:** June 22, 2008, 06:12:06 pm »

Daz,
Barry is the owner of Westbournes.
BUT to get things clear are both motors connected directly to the ESC or wired in series, IE fron esc to 1 motor to second motor and back to ESC.
If they are wired in series each motor only gets 6 volts so could be the problem.
Any chance of a pic of the wiring?

http://www.modelboatmayhem.co.uk/forum/index.php?topic=6169.0 Pic 3

Bob

portside II · « **Reply #14 on:** June 23, 2008, 04:55:28 pm »

sorry Bob .they are wired in parelell as in pic 3 but without the fuses so they are both getting 12v .
i will be doing some experimenting aswell with different batterys as 1x 12v 7ah bat is nearly enough ballast but 2 is too much ,but 4x 6v 4ah are lighter so i may try 2 esc's running off two bats each giving me 12v at 8ah per motor .then again i might stick a pair of T motors from Brian at MMM i will have to check the wallet/purse first.
daz

Casper · « **Reply #15 on:** June 24, 2008, 10:24:50 pm »

There are a number of threads running regarding motors etc, there also seams to be many who favour gearboxes, reduction systems to those working direct.

In my 30 years of model boat building I have come to one conclusion, gearboxes don't add value to driving my models....

I have all my models equipped with one standard drive line, its a 540 that is rewound to give the torque/speed profile I need. If you reduce the speed of a 540 then the torque rises, rises to a point where it will happily drive 70mm brass props direct moving very heavy models. I am building a Pegasus 3 now and it has 540 motors tuned for semi fast models.

Doing this motor rewinding lark is not hard, its simple, once you have a set of formula you can 'create' a motor to be what you need it to be, and for about £5 all in! I use cast of 540s motors from buggy racing! If you have a twin screw model you can wind them 'handed' they both then run forward/reverse, not one forward one reverse and standard off the shelf motors would.

On ESC they can be noisy at low speed, this is cured by disconnecting the motor from the shaft. Just use Huco coupling ends on the motor/shaft, then use 10mm silicone fuel pipe between! the tube absorbs the motor noise and corrects for bad alignment.

So here we are, my way to drive a model covers everything from heavy displacement craft through to semi fast models, silent, low power use 6v 1amp nominal each.

M

FullLeatherJacket · « **Reply #16 on:** June 24, 2008, 11:31:37 pm »

If anyone would like to try Casper's rewinding exercise then I have a copy of a very informative article on the subject by Glynn Guest, from an old Model Boats magazine. If anyone would like a copy then please PM me with your E-Mail address.
All proceeds will be donated to the Stoke-on-Trent Rest Home for Bewildered College Lecturers................... :angel:
FLJ

OMK · « **Reply #17 on:** June 25, 2008, 12:25:30 am »

Casper, can I pick your brains for a minute? You said: "Doing this motor rewinding lark is not hard, its simple, once you have a set of formula...."
You got me intrigued by that formula.
Can you elaborate, pse?

FLJ:
...and can I take you up on your offer? You still have my address, oui?

Heap'um thanks!

FullLeatherJacket · « **Reply #18 on:** June 25, 2008, 11:23:28 am »

Quote from: PMK on June 25, 2008, 12:25:30 am

FLJ:
...and can I take you up on your offer? You still have my address, oui?

Heap'um thanks!

Oui. Ahve jus sented it, mush.
FLJ

barry park · « **Reply #19 on:** September 01, 2008, 01:02:35 am »

Guys, Help me out......... I need this magic formula too!

I've unwound some transformers,bought coils of enamelled wire,ripped 10 kilos of motors out my models and have taken the armatures out some motors in preparation.
I need to windup these motors and clear this room before Wednesday or I'm for it!

If none of you guys can tell me how to change the torque characteristic of a motor by changing the turns ratio this creation will be donated to my favourite deserving charity.

Yours sincerely,
Barry Park
Balticmill,
Gateshead
p.s. Here's a pretty picture of a boat. http://www.tate.org.uk/tatetotate/

BarryM · « **Reply #20 on:** September 01, 2008, 08:46:00 am »

Daz,

I use geared MFA in a paddler without noise problems.
As far as performance of your craft is concerned, you seem to be concentrating on shaft rotation speed. What about prop pitch? If it's too fine, you can rev away all you want but you're not going anywhere. :)

Cheers

Barry M

ianb · « **Reply #21 on:** September 01, 2008, 01:09:15 pm »

Portside 11,

I built an Al Khubar and put in 2 MFA geared (6:1) motors. They didn't suit me, to put it as politely as I can, so, on Laurie White's advice I ripped them out and put in a couple of Graupner 720 BB Torque motors on direct drive. Like night and day! I cut the power back on the speed controls and the transmitter ATV and my Al Khubar runs like a sports car or a Rollls Royce depending on my mood.

Put 2 of the same motors into my Arif and I am really pleased with the power available. the smoothness, and the absence of any noise from the drive train.

Yes, I like the Graupner 720BB Torque. A quality motor in my opinion. No, I don't like gearboxes.

Cheers,
Ian

portside II · « **Reply #22 on:** September 01, 2008, 11:19:36 pm »

Cheers Barry , your prob right as the prop pitch may be one of the solutions to try as the tug has the original props still fitted .
Ian ,good idea to fit the 720BBs as i like direct drive too .
I will get back to you both on this subject soon .
daz

barry park · « **Reply #23 on:** September 02, 2008, 12:18:32 am »

Daz,
You want to load your motor/gears with bigger coarser prop until shaft revs fall to half the no load revs of the motor.
OR cut the gear ratio. That figure is where maximum power is delivered. If you are slower than half no load revs then you go the opposite way.
Barry Park

p.s. Check the £2 motors in the pretty picture............On 12 volts

0.26 Kgcm/Amp torque
no load current 0.36 amp
stall current 6.2 amp
max power 20 watt at 2000 rpm & 3.2 amp

I'm right with the guys on buying hight torque motors!...I should have called my sculpture: Spotlight on good motors.

p.p.s. Back to this elusive magic formula to increase motor torque by changing number of turns.
Casper,your a bigger windup than me or you didn't realise you make 3 volt motors out of 6v ones.

portside II · « **Reply #24 on:** November 02, 2008, 02:02:46 am »

cheers Barry , i have since put the geared motors in a scratch build pusher tug spinning 70mm 3 blade props in korts .
Yet to have water trials as the hull is no way ready to look at water never mind sit in some .
and the dutch river is also on the bench in bits having a new deck fitted and motors ,i will also fit new props and the new ACTion dual 20a esc /mixer

.Oh so many things to do .
daz

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Author Topic: MFA geared motors (Read 10191 times)

Casper

FullLeatherJacket

OMK

FullLeatherJacket

barry park

barry park