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Author Topic: "Graupner Glasgow"  (Read 596 times)

mikew

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"Graupner Glasgow"
« on: September 05, 2021, 11:12:05 am »

What would be a good electric motor combination with the "Glasgow" please.?.
Mike
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Mike

tony52

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Re: "Graupner Glasgow"
« Reply #1 on: September 06, 2021, 01:16:39 pm »

Mike,

When the steam plant was removed from mine, an MFA 11:1 geared motor using the 3:1 ratio gears was used. These Graupner gears are now no longer available. The battery was a 7.2v Nimh. There were no performance problems other than the gear noise. I've attached a thread from the Model Boats forum which covered the work.


https://www.modelboats.co.uk/forums/postings.asp?th=89240&p=1


Bob Abell used a 50:1 MFA geared motor on 12v, with a plastic chain drive. He complained of poor performance, but the drive was silent. Again, I've attached the thread from Model Boats forum.

https://www.modelboats.co.uk/forums/postings.asp?th=71620&p=1


Hope this helps,


Tony
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Colin Bishop

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Re: "Graupner Glasgow"
« Reply #2 on: September 06, 2021, 03:00:02 pm »

I am currently experimenting with a paddler about the same size as the Glasgow with 3.5 inch diameter wheels. A friend has printed me out a set of parts for feathering wheels but I will also be trying out the Glynn Guest fixed float design.

I am using two MFA 11:1 385 geared motors with a reduction on the final pulley drive. Not been able to properly test it yet but 7.2v gives 312rpm on the wheels at around 0.5 amps no load. The speed is probably too high but can of course be reduced on the throttle.

I have made some motor mounts using Makerbeams so the motors can be slid fore and aft to adjust tension on the driving bands and allow for using different pulley sizes on the wheel shafts.

 https://www.technobotsonline.com/makerbeam.html

The original vessel, ps Bilsdale, had independent paddle drive so I'm doing thngs the hard way!

Colin

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mikew

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Re: "Graupner Glasgow"
« Reply #3 on: September 06, 2021, 03:14:41 pm »

Hi Tony and Colin


Many thanks for your replies, strange how things turn out, this morning I visited "Hobbies" my local shop and bought a Torpedo 500 11:1 ratio and using a couple of ali toothed wheels and toothed belt roughly 3:1 I seem to have achieved  the desired result. What I've never seen is that mounting system "Makerbeams" they looks ideal when fitted I will post a picture.


Many Thanks to you both.
Mike
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Mike

Peter57

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Re: "Graupner Glasgow"
« Reply #4 on: September 07, 2021, 01:07:05 pm »

Hi Mike,
Sorry if I am a bit late adding to this thread.
Have you thought about using separate motors for each paddle? I have a second hand "Glasgow" which is set up with two MFA geared motors (each with an ESC) allowing "tank" steering. The motors run (together with other electronics) from a 12V battery via a power distribution board and 10A fuse boards.
Regards
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mikew

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Re: "Graupner Glasgow"
« Reply #5 on: September 07, 2021, 02:08:54 pm »

Hi Peter


Thanks for the info, must get the distribution board and inline fuses.


Cheers
Mike
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Mike

Colin Bishop

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Re: "Graupner Glasgow"
« Reply #6 on: September 08, 2021, 01:57:31 pm »

Just for information, I have now fitted the new motor mounts into my Bilsdale hull and the method of tensioning the drive belts works a treat. The mounts are glued in. The motors can be removed but it will be a fiddly job to refit so I will probably cover them in cling film while I finish off the hull.

The distance between the motors and the paddle shafts vary a bit due to the siting of the shaft and shape of the hull but the drive ratios are the same. For some, not immediately obvious, reason the forward motor with the longer drive belt gives 322rpm and 0.6amps at 7.2 volts whist the aft motor is delivering 334rpm at 0.5 amps. Both wheel shafts seem to be equally free running. It's difficult to get the tachometer on the motors themselves as the aluminium pulley is reflective. I may try masking it though.

By running the motor with a wattmeter in the circuit it is possible to monitor the current draw while moving it along the track to adjust the tension which in turn makes it very easy to identify the 'sweet spot' where the belt has maximum tension to avoid slipping without pushing up the current draw.

Just got to finish the rest of the boat now and assemble the feathering wheels.  %%

Colin
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mikew

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Re: "Graupner Glasgow"
« Reply #7 on: September 08, 2021, 03:59:28 pm »

Interesting set up, but think as its my first paddler I will stick to the single drive.


The "Makerbeams" I ordered on the 6th have just arrived, that's swift service. Tomorrow task then.


I look forward to the finished boat.


Regards
Mike



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Mike

Colin Bishop

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Re: "Graupner Glasgow"
« Reply #8 on: September 08, 2021, 04:40:58 pm »

I forgot to mention that I used spare T bolts and the shorter screws to make end stops on the 'tracks' which prevents the motor being inadvertently moved too far in which case the mounting bolts drop out and are a faff to put back if the track is stuck inside the hull!

You can see them in the photo.

Colin
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mikew

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Re: "Graupner Glasgow"
« Reply #9 on: September 08, 2021, 04:44:22 pm »

Yep can see them, thanks for tip
Mike
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derekwarner

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Re: "Graupner Glasgow"
« Reply #10 on: September 08, 2021, 11:39:48 pm »

..... "It's difficult to get the tachometer on the motors themselves as the aluminium pulley" ......

Colin.......try black Textra Colour on the complete circumference of the end shank hub of the pulley, then scratch a heavy/deep line on axis into the metal of the hub

The scratch in the aluminium will provide a bright reflective surface line & easily distinguished to provide an accurate RPM on the digital tachometer

Most light-duty [inexpensive build] DC motors have a small % of speed variation depending in direction of rotation...this can be due simply by the angular set of the carbon brushes in the brush holders to the axis of the shaft/commutator.....

I wouldn't be too concerned about this, as if you are to use independent control, any variation could be countered by the Tx signal or trim

Derek
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Derek Warner

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RST

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Re: "Graupner Glasgow"
« Reply #11 on: September 09, 2021, 12:16:30 am »

Hi Colin,


Luxury of a tacho!  Just looking in simple terms while you do your best to ensure tension on both drives, one o-ring is longer than the other and will need different tension to keep the ring from flapping on the longer one. I would imagine that is the reason for the small difference in RPM -you don't have equal drive lines so there will be different (small) losses between the two coupled with two cheap (good enough) rather than precision motors may not give same output anyway as Derek alluded to.  I'm sure that is patantly obvious anyway.


Rich
« Last Edit: September 09, 2021, 12:47:52 am by RST »
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Colin Bishop

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Re: "Graupner Glasgow"
« Reply #12 on: September 09, 2021, 08:35:13 pm »

Yes, Derek and RST, the rpm difference isn't likely to be significant. Thanks for your input. ( I would have responded earlier but have clambering around HMS Victory today. you can now get right underneath her! Something for another topic.)

The tacho isn't really a luxury, just a cheapie Chinese hand held, but I was having problems in estimating the rpm I was getting. Glynn Guest tells me that his fixed float paddle wheels are best run at around 150rpm but a trawl through the Paddleducks website suggests that others have used wheels at 300rpm so I wanted to cover all the bases. I have some larger final drive pulleys so can slow down the base rpm easily enough if required. At the moment I don't know what will be best for my as yet unassembled printed feathering wheels. All good fun!

I seem to have hijacked this topic a bit but given that my Bilsdale and the Glasgow are around the same size I thought it would be useful to share what I have learned so far.

Colin
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mikew

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Re: "Graupner Glasgow"
« Reply #13 on: September 13, 2021, 09:43:21 am »

Now onto the electrics.


Mike
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Colin Bishop

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Re: "Graupner Glasgow"
« Reply #14 on: September 13, 2021, 11:37:00 am »

Very neat Mike. The gearbox on your motor is a fair bit longer than the ones on mine.

Colin
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mikew

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Re: "Graupner Glasgow"
« Reply #15 on: September 13, 2021, 12:23:36 pm »

Think I've got a wonky camera <:( , seems to have stretched both motor body and gearbox cover, which is only 1-1/4"


Mike
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Colin Bishop

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Re: "Graupner Glasgow"
« Reply #16 on: September 13, 2021, 01:07:24 pm »

Yes, it does look like lens distortion on a second glance!

Colin
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mikew

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Re: "Graupner Glasgow"
« Reply #17 on: September 14, 2021, 04:51:10 pm »

That's the simple electrics done, hope for  sail tomorrow !!!!
Mike
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Colin Bishop

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Re: "Graupner Glasgow"
« Reply #18 on: September 14, 2021, 04:57:59 pm »

That's a very neat installation Mike. Hope all goes well with the trials and make sure you report back.

My model has a way to go yet. I have been repurposing an old white metal Caldercraft rudder to save making a new one. Still a bit more sanding to do before the gumstrip goes on.

Colin
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mikew

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Re: "Graupner Glasgow"
« Reply #19 on: September 14, 2021, 07:25:03 pm »

Thanks for that Colin, Next step is to make the lights work, they are grain of rice, thinking of changing to LED's.


Must confess I like working with brass  I found whit metal to soft for my liking guess always frightened of it wearing away !!!


Regards
Mike 
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Colin Bishop

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Re: "Graupner Glasgow"
« Reply #20 on: September 14, 2021, 07:33:18 pm »

Yes, I ditched the white metal rudder when building the Caldercraft kit but it's come in handy for the experimental paddler.

Re lights, I think that GoW bulbs on lower than rated voltage are more realistic than LEDs for navigation lights.

Colin
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