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[dodgy geezer]

Steam engines are mostly crude and often inefficient, but most of us love them, it's all a matter of taste. The magic of seeing the workings doing their stuff is entrancing..

..and the electric smell of the oil on the brushes! Never forgotten...

.......
I did have some thoughts about using a period motor and maybe driving it from a hidden source which could be done with a drive band with a pulley to the Comet.  The u/j on the Comet driving the prop.
......
Hi Dodgy, how is the 'Scope?
Roy

You could also hide a modern brushless motor behind a bulkhead, and drive the Comet by extending the non-prop-shaft end to align with the hidden motor. It would surprise onlookers, until the Comet armature shook itself to pieces. They were not balanced...


The scope has revived my electrical bench - grateful thanks! I've been able to trace a fault on an old Micron, and am currently trying to get an old Remcon 12 to function. I like to keep the old systems running...


One problem is that, though the electronics seem to survive well, and can be obtained on ebay occasionally, the actuators seem to be forgotten about and are like hen's teeth. To address this, I have designed a (fairly!) reliable single channel actuator, complete with 'quick-blip' switching (do you remember that?). The actuator just uses some cheap readily-available geared motors, microswitches and a bit of perspex. You can see it working here:


http://oldboats.tk/single%20channel%20actuator.mp4


If anyone wants some drawings and a circuit diagram send a PM.  It would be ideal to control a Comet-motored boat - assuming that you can find a pond that is safe enough to use 27Mhz and bang-bang controls on...

[DJW]

Evening All


Just thought I'd post latest current draw for the Comet...





This if far closer to the original specifications and reviews from the 1950s suggesting 0.4A with no load.  This is after using some very strong neodynium magnets on the poles of the Comets horseshoe magnet to re magnetise it. This reading is after the neodynium magnets had been removed, so with Comet in original configuration.


Regards to all.
David.

[DJW]

Afternoon All

I've stripped down the second Comet, will give it a good clean and re magnetise the horse shoe magnet.  The shaft is a bit tight but I think it's just gummed up with old oil as a bit of WD40 improved the situation so I'll take a look at that before rebuilding.  It'll be interesting to be able to compare the two apparently identical motors when it comes to no load current draw.



On a related matter, I've noticed that the 'Meteor' shaft is a little sloppy on it's bearing surfaces, I was thinking of using broaches to open up the paxolin to accept new brass sleeve bearings.  I have both on hand from restoring a grandfather clock a few years ago.  What do we think..?  Reasonable plan, or better to try to make up new paxolin endplates..?





Best regards to all.
David.

[dodgy geezer]

Afternoon All

I've stripped down the second Comet, will give it a good clean and re magnetise the horse shoe magnet.  The shaft is a bit tight but I think it's just gummed up with old oil as a bit of WD40 improved the situation so I'll take a look at that before rebuilding.  It'll be interesting to be able to compare the two apparently identical motors when it comes to no load current draw.



On a related matter, I've noticed that the 'Meteor' shaft is a little sloppy on it's bearing surfaces, I was thinking of using broaches to open up the paxolin to accept new brass sleeve bearings.  I have both on hand from restoring a grandfather clock a few years ago.  What do we think..?  Reasonable plan, or better to try to make up new paxolin endplates..?

Best regards to all.
David.

Easy to cut new end plates - the templates are on the web site. But cheaper to use new bushings, if you already have them.


You can get small ballraces the same size as those bushes, and that would be the most sophisticated solution! 


For the Standard and above, the paxolin end plates are doubled, and a temporary solution is to losen them and slightly offset the shaft holes, thus holding the shaft a bit firmer..

[DJW]

Thanks for that, so I'll add the new brass bushes first, any issues with that and plan B will be new end plates.


I now have the second Comet refurbed, up and running again, good to have the pair ready to add to a boat as swap out units.








On the power supply, the second Comet is in the right ballpark with no load current, maybe a bit of running in or tweaking will change / improve the figure.  This is first run of second Comet:





Best regards to all.
David.

[roycv]

Hi David lovely job!
How did you re-magnetize the magnet?  I just put a 8mm neodimium magnet on one end.
Roy

[dodgy geezer]

I second roycv's comments! The polished brass looks particularly fine...

[DJW]

Thanks both.  As part of the cleaning process both were stripped, brass parts were soaked in a citric acid / fairy liquid (other fine liquid soaps are available...) a tad of bicarbonate of soda and warm water.  Then wire wool on the mounting plates.


I've noticed in the pictures that the magnets are in slightly different positions vertically compared to the paxolin plates, I thought I'd aligned then to the flat surface of my desk as I assembled them. I'll check this and see if it has an impact on that benchmark of no load draw.


I ended up using two 20mm x 10mm neodymium magnets attached to the ends of the horseshoe for a few hours, overnight basically.  That seemed to pep up the magnetism quite a bit.


Best regards
David.

[dodgy geezer]

....
On a related matter, I've noticed that the 'Meteor' shaft is a little sloppy on it's bearing surfaces, I was thinking of using broaches to open up the paxolin to accept new brass sleeve bearings.  I have both on hand from restoring a grandfather clock a few years ago.  What do we think..?  Reasonable plan, or better to try to make up new paxolin endplates..?
....
David.

A perfectly true Taycol should just hum gently when running. If the bearings are sloppy or the shaft is bent, you can detect a distinct buzz.

[DJW]

Progress with the Meteor...

I've sized two new brass plain bearings and pressed them into the end plates, kept the bearings flush on the inside faces:



And the other side:




On, and supporting the shaft:






And the rest of the motor gets a bit of TLC, everything cleaned up and bathed in a mix of 3 in 1 and WD40:



And putting it back together:





And back together:







After a check over, it went to the power supply...



I checked forward and reverse, both working, reverse giving about 50% of forward speed as it should.  I'm not putting the manual reversing mechanism back, I'll be adding diodes for better RC control.

The motor is running / sounding very smooth, it's humming..! I'm very pleased with it.  It also throttles pretty well, I tested it up to 6 volts, and down to 2 volts, it remained stable throughout.  I understand it can be run up to 12 volts but I see no need to take it there to be honest.





Thanks for the support, I now have three refurbed Taycols and will be looking at how best control them using RC and turn to the boats for them.  Meant to add, I'll give an update once I have the diodes and capacitors fitted to the Meteor.  And I'll need to check what I should do to suppress the Comets.

Best regards
David.

[dodgy geezer]

Progress with the Meteor...

.......


The motor is running / sounding very smooth, it's humming..! I'm very pleased with it.  It also throttles pretty well, I tested it up to 6 volts, and down to 2 volts, it remained stable throughout.  I understand it can be run up to 12 volts but I see no need to take it there to be honest.

.............

Thanks for the support, I now have three refurbed Taycols and will be looking at how best control them using RC and turn to the boats for them.  Meant to add, I'll give an update once I have the diodes and capacitors fitted to the Meteor.  And I'll need to check what I should do to suppress the Comets.

Best regards
David.

The commutator is the weak point in the smaller Taycols, and higher voltages wear them out faster. The big Taycols have a massive commutator - on one review it was estimated that the Standard could run at 20v.


If you want the ultimate in sophistication, the web site has a polarity detection and switching circuit for reversing using an op-amp....

[roycv]

Nice restoration but almost certain max voltage is 6 volts.  Originally meant for dry battery, probably 2 off cycle headlight batteries. 
I have used ordinary brass tubing for bearings, one a good fit to the shaft a second tube a close outer fit and a washer on back up (reemed to fit if necessary) all soldered together and then cut to fit.
I have one of the small mystery motors I do not know either!
Roy

[DJW]

Afternoon Roy


Well I'd have agreed with you about a 6V max until I saw a review of the Meteor from 1958 (kindly sent over by Circlip), but I'll be staying at 6V for sure.








Best regards
David.

[roycv]

Hi my 6 volt comment was meant for the Comet motor.  I would happily run the Meteor on 7.2 volts.  I would follow in your footsteps for the Meteor and other Taycol field coil motors I have but I shall never use them to power a boat so they stay as they are.
Regards
Roy

[dodgy geezer]

As I recall, the commutators for the Comet and Meteor are pretty similar.  The commutator is usually the weak point for the smaller Taycols, and the web site shows one in poor condition being repaired...


I suspect that 12v in 1958 was rarely delivered with the same current which would be common today!  I agree with rovcv that a modern 12v is really too much for the smaller Taycols.  Typical examples of the Comet which you will meet today will have less magnetism than design, and that means that the motor will run poorer, with a higher current drain and consequentially more commutator wear. 6v seems a good maximum to me.


The Meteor and other field coil motors won't change their magnetic characteristics, of course, and can be run up to whatever limit your commutators can take, so roycv's advice is sound here. Remember to lubricate the brushes!


Incidentally, many (most?) electric cars use permanent magnet motors.  I wonder how long the magnetism lasts in them? It will give out eventually...

[DJW]

Afternoon All


Thanks Roy and Dodgy for the input, and apologies if I've confused the issue by adding the Meteor to this thread.  I was so pleased with the Comets that I saw the Meteor on ebay and thought why not..!


It did give me a hint of a plan, I've built the 1/10th Amati Aquarama and have the scratch 1/5th in build.  I may do a similar approach with the Sea Urchin.  Build it as it comes from Slec and use a Comet, but take templates to allow for a double size build, and maybe use the Meteor.  The Slec kit is 16", so a doubling would be 32", sounds about right for the Meteor. I recall an article in MB that took the size of the Sea Urchin up to 28" I think. Any thoughts on that..?


Best regards
David.

[zooma]

I was also following that pair of Comets on eBay ?with something similar in mind, but I am pleased that they ended up with a good home and that they will be used.

[Davo]

Looking at the amount of views this little Sea Urchin has had (168,371 to date) it shows an amazing interest in vintage boats.  As a young builder of a Sea Nymph around 1964, I also love this era and type of modelling. 
I still run a Sea Nymph (from a 1990 reissue kit) but using a 2822 Out runner brushless motor and small LiPo battery.  These small boats do not have much displacement and so hardware weight is a concern.
Mu old battered Sea Nymph was rebuilt to a longer version as at the time I was using a brushed motor and large 7.2V buggy batteries.  This also now runs brushless as above with petrol motor performance.
Looking forward to the Sea Urchin on the water.
David

[Davo]

If the Sea Urchin is being built from scratch, perhaps consider upscaling the model to accommodate the heavier motor and batteries etc.  Might look good at 24".
David

[DJW]

Afternoon David


Yes I agree, and as such we have a bit of 'project creep' already.  Plan is currently to build the standard 16" Sea Urchin that I have here ready to start and that's going to use one of the Comets.  Then I have a nice example of a Meteor, that I think might be right for a Sea Urchin in the 24" / 26" LOA range.  Or...  If I can find a nice Taycol Standard in next month or two, it would be a better fit in something like a 32" Sea Urchin.


And on another related matter, before the builds take place I am going to test a couple of conventional ESCs that I have here, and see if I can improve on their performance (not as in speed, I'm thinking more about control and reducing arcing, brush / commutator wear) with a homebrew ESC optimised for these vintage motors.  For example I'm aware there are recommendations and differing opinions re the PWM range that the Taycols are comfortable with, I'd like to evaluate by testing for myself and will share the results.


Best regards
David.

[HMS Invisible]

...
And on another related matter, before the builds take place I am going to test a couple of conventional ESCs that I have here, and see if I can improve on their performance (not as in speed, I'm thinking more about control and reducing arcing, brush / commutator wear) with a homebrew ESC optimised for these vintage motors.  For example I'm aware there are recommendations and differing opinions re the PWM range that the Taycols are comfortable with, I'd like to evaluate by testing for myself and will share the results.


Best regards
David.

I've noticed different perspectives but I can't recall contrary opinions on PWM, spark erosion and arcing.

[dodgy geezer]

.......
And on another related matter, before the builds take place I am going to test a couple of conventional ESCs that I have here, and see if I can improve on their performance (not as in speed, I'm thinking more about control and reducing arcing, brush / commutator wear) with a homebrew ESC optimised for these vintage motors.  For example I'm aware there are recommendations and differing opinions re the PWM range that the Taycols are comfortable with, I'd like to evaluate by testing for myself and will share the results.
.....

The Taycol website would certainly be interested in publishing any such findings.  I find that the field-wound motors behave rather differently to the perm magnet types, and that ferrite rings on the power leads are quite useful in suppressing spikes which upset the ESCs...  You may also be interested in the op-amp reversing circuit shown on the site...  See http://taycol.tk/relay1.html

[DJW]

Afternoon All


Maybe my choice of words and explanation could have been better...  The Taycols are new to me, but I'm enjoying the challenge of trying to get them running well and understanding them a little better.  Some of what I've read is contradictory, not particularly on here, but generally.  As was pointed out earlier in the thread, a faithful vintage build would go for a rheostat control or straight on / off or similar methods controls from same era.  I'm not taking that route, but that means working with the Tacols to arrive at a good solution.


I have scoped out and have in build an Arduino Pro Mini based ESC with a pair of D4184 Mosfet modules, one forward, one astern. Initially for bench testing, but then for rollout if testing goes well, and seeing if I can exceed the capabilities of the off the shelf ESCs in the context of and focussing on the Taycols.


This will mean direct control and testing of various PWM frequencies, initially evaluating in the 1 to 4khz range while observing the motors, listening and feeling how happy they are, current consumption and so on.  Also looking at a 'soft ramp' approach to passing power to the motors, being able to alter the ramp duration when feeding in and reducing power, aim being smooth and progressive power.  I think modern batteries /  ESCs can deliver so much more current that the controlled soft ramp will be very useful. Another option to evaluate is to use a sine ramp rather than linear, so change the shape of the power climb, might be a bit subtle on a propellor loaded motor, but I'd like to have the option.


The code allows for these optimal settings to be retained for each motor model and type (Comet and Meteor at the moment but others could be added.) Or even by specific motor given the motors may have different characteristics being the age they are.


I know that some will say this is not needed, some or all of these settings can be programmed into off the shelf ESCs, but I quite like the idea of more flexibility.  We'll see if it pays off..!  If it does I'm more than happy to share circuit and code.


Best regards to all.
David.

[dodgy geezer]

......

I have scoped out and have in build an Arduino Pro Mini based ESC with a pair of D4184 Mosfet modules, one forward, one astern. Initially for bench testing, but then for rollout if testing goes well, and seeing if I can exceed the capabilities of the off the shelf ESCs in the context of and focussing on the Taycols.


........

Watch out for heavy induced spikes coming back down the power line.

[HMS Invisible]

I'm glad at least someone is looking into what these parameters do.

RC electronic speed controls wouldn't run below 10kHz if it weren't for complications in getting there. The obstacles for the esc designer are the complexity in FET drive, and the need for an additional bulky, low esr capacitor. The NANKDAF psu with the current limit cranked up to maximum, and a 2,200 uF at its output, would simulate that.
 500Hz to 4kHz is high enough to get past mechanical resonance but 4kHz doesn't eliminate the low-throttle current ripple for a low turn (low inductance) motor.
  So if the project goal was to take the sledgehammer to elimate arcing I would use to the psu to show the achievable limit, rewind with more turns and increase esc frequency. 
 I've expressed my opinion on ramping before. It sacrifices a crisp throttle response to make it woolly. It's an easily implemented gimmick.