Radar Drives

[Michael JeenesParticipant @michaeljeenes66772]

[Michael JeenesParticipant @michaeljeenes66772]

Hi All. I am building the 'Portgarth' Tug from MMM and would like to have the radar working. Problem is that any drive from within the deckhouse would have to pass through the largely glass wheelhouse and look rediculous.It would also have to undergo several changes of direction requireing some sort of flexible drive. Is it possible to buy small, slow running motors that could fit direct to the radar without looking out of place?

[mike farrellParticipant @mikefarrell21522]

Hi Michael, Like you I am building a MMM model but the smaller Anglian man and intend to drill through the roof, floor and mounting a small 30 rev. per minute motor to the floor with connections to e an ancillary power supply,Main problem is to remember to disconnect before removing superstructer from the deck.There is a few on sale on that other bay . T he drive will be connected via a Sullivan plane ailerons connecter which I,v had t over from past projects .Otherwise ring Dave at MMM,he might give you better advise. Good luck Michael

[Dave MilbournParticipant @davemilbourn48782]

https://catalog.precisionmicrodrives.com/order-parts#dc-gearmotor
A fascinating website for very small motors, but just look at the price of their Mabuchi motors……£12 for a bog-standard 540! Ouch!
Dave M

[Michael JeenesParticipant @michaeljeenes66772]

Thanks Mike & Dave.

The idea of placing a geared motor (I have two from Maplins) under the deckhouse floor and using a 'flexidrive' passing through the wheelhouse was considered but as stated above it would look out of place. I have been on board the 'Portgarth' twice and will try to fill the wheelhouse with detail gleaned from the photos taken. Any drive from below would have to come through the center control desks and look out of place. Fitting a small motor directly to the mast and radar is more in keeping with full size practice if I can manage it. I will have a look at the website Dave and see if any product will do the trick. I do not understand electronics, it is all jibberish to me so any purchase will be a risk.

MJ

[ashley needhamParticipant @ashleyneedham69188]

MJ. If you have no luck, I recon that thick nylon fishing line might just do the trick as a flexidrive, and will be clear(ish) to boot. Would be stiff enough for the very low torque needed, and even the "thick" stuff would be very thin (if that makes sense).

Ashley

[Michael JeenesParticipant @michaeljeenes66772]

Hi All.

Thanks for your inputs. I will take your idea on board Ashley..maybe make up a test bed first if the following does not work out.Thin 'strimmer' plastic cable may also do it.

I have been in touch with "precision micro drives" Dave. they have been most helpful. Despite the possible costs involved for such a small function I may give it a try. They have a motor 6mm dia x 16mm which could do the job on lower voltage to reduce speed. Thanks for the introduction.

[sammykParticipant @sammyk]

hi michael ,i used an old servo with the electronics removed and ran it on 1.5 volts (aa battery) and costs next to nothing .regards sammyk

[Michael JeenesParticipant @michaeljeenes66772]

Never gave that a thought Sammy. I have two or three mini/micro servos with striped gears. will have to locath them and see what gives.

thanks MJ

[sammykParticipant @sammyk]

michael you need to keep the gears in or it spins to fast, then again its worth a try

[Michael JeenesParticipant @michaeljeenes66772]

Found that out Sammy. No room for gears as well.

Have found right size motors but they all too fast.

Next thought…Can a PC board be used to reduce the power delivered? Now this question comes from a man who knows more than nothing about 'electronics', all jibberish to me so any reply should treat me as an idiot. If it is possible the I will search for a local person who can make it for me. Just how complicated can a simple task like powering a radar be??????!!!!

MJ

[ashley needhamParticipant @ashleyneedham69188]

MJ.

Maplins do a small board with a knob on the front to provide a variable voltage supply which is easy, however I doubt that you will get a non-geared motor to go slow enough..after all you only want about (say) 30 rpm or something, and that is very slow..

Ashley

[Michael JeenesParticipant @michaeljeenes66772]

Cheers Ashley. I will look it up online.

MJ

[Colin BishopModerator @colinbishop34627]

That micro motor site looks interesting. Some of the motors are small enough to drive props on plastic kits such as the pods on my Revell Queen Mary 2 but the problem would be keeping the water out at the shaft end. (The other end could be encpsulated in resin)

Colin

[Michael JeenesParticipant @michaeljeenes66772]

To be honest Colin I would strip down a servo or two and use the motors, far cheaper. I have done this in the past with Revell kits. Most light oils should keep the water out or Lithium based grease used on chains by cyclists.

If I can find a way of reducing the speed on the 6mm x 16mm motors from the motor site they will just about fit within the base of my radar if I use 'modelers licence' and make them just a little larger than scale

MJ.

[sammykParticipant @sammyk]

can the servo not be mounted in or under the wheel house and use a thin clear plastic rod to drive the radar? sammyk

[Michael JeenesParticipant @michaeljeenes66772]

It may come to doing something like that. the drive would have to go through several changes of direction. I am looking at fishing line or strimmer chord as the drive. taking my time to decide.

have a look at the photos on http://www.shipspotting.com/gallery/search.php?query=portgarth&x=26&y=8 you will see how the radars are mounted, direct drive from below is not possible.

MJ

[John Tybjerg 1Participant @johntybjerg1]

Michael, Try Modelling Timbers at http://www.modellingtimbers.co.uk . I saw them at the National Show at Coalville and they have some nice small motors set at 33 rpm. 12 volt have a short waiting list, not sure about 6V.

John

[Michael JeenesParticipant @michaeljeenes66772]

Hi John. thanks for the intro to the above site. I had a look and the motors are too large for direct drive. i am now toying with the idea of fitting a false ceiling in the wheelhouse to hide the motors, flexi drive will still have to negotiate two tight bends…the challange remains. These motors are not too bad on price so may be worth the investment.

Any solutions out there to the 'electronics' way of slowing down a 3v motor running at 1300rpm to a realistic speed???

MJ

[MzeeParticipant @mzee]

Michael, have you considered using the tiny servo motors from a video camera lens system? Some years back I had my vidcam in for service and noticed that they no longer rpair lens systems but simply replace the units and discard the old along with attached servo motors and their gearboxes. I casually asked what they did with the lens units they took from cameras and was told that they were discarded as junk. Imagine that – chucking out all that useful (to a model maker) stuff? I was given a small basketfull of lens systems with servos and will be using one of these to drive the radar scanner on a large tug model. No problems feeding a drive shaft up a hollow mastsection but in any case the thin drive shaft would not be conspicuous when the model is on the water. Think about it.

Regards, Robin

[Francis MacnaughtonParticipant @francismacnaughton39461]

I bought one of these 6mm diameter geared down motors from Gismoszone (which i think is Hong Kong based) for radar drive several years ago and it seems OK but I haven't got round to installing yet but it is the smallest i know of.

**LINK**

[Dave MilbournParticipant @davemilbourn48782]

Any solutions out there to the 'electronics' way of slowing down a 3v motor running at 1300rpm to a realistic speed???

The big problem here is that small motors have very little inertia in their rotating parts so they require a significant voltage to start them. At this voltage the speed will be quite high, but any less and the motor won't run. Variable voltage is therefore not an option.

The conventional way of controlling a motor's speed is to "pulse" the full voltage on and off, rather like pedalling a bicycle and then coasting for a short while before pedalling again etc. While this works for most drive motors, the speed reduction isn't so drastic as would be required here. Put simply, you would need to pulse the motor off for 40 times as long as it would be on to get approx 33rpm from 1300, and this would be horribly obvious as a jerking motion.

Like black smoke machines, radar drive motors small enough to fit into scale housings are elusive beasts; if you find one then please let us know – O, and it has to cost only pennies, of course!

Dave M

[Michael JeenesParticipant @michaeljeenes66772]

Thanks Francis & Dave.

I have bought two 6mm x 21mm geared motors and will try to hide them in the roof lining of the wheelhouse and base of the mast structure with a flexi drive if I can but failing that a fine 'piano' wire or clear plastic direct drive will have to suffice. As pointed out, this will not show at distance and is not quite so important in the great sceme of things (I will know that it is wrong but will others notice??). The electronics route is a none starter, I kinda understand it now, thanks.

MJ

[Southern SailorParticipant @southernsailor76583]

Hi Michael, The general way of driving the tail rotor on a model helicopter is to use a small geared motor at the tail rotor. Perhaps you could use such a motor for your radar, suitably geared. Helicopter spares are readily available and this should be as well. Could you share the solution as I am also busy with Portgarth from Mobile Marine Models. I am also looking for details of the control desk in Portgarth. Any photos available? Cheers and happy sailing. Brian

[Michael JeenesParticipant @michaeljeenes66772]

Hi Brian. I gave up on the 'flexi drive' approach and fitted two 3v geared motors from (http://www.precisionmicrodrives.com), they give about 27rpm which looks ok to me, a little expensive though. They are direct drive via a plastic rod through the radar support tube, connecting is with 'electrical shrink tube'. The motor protrudes above the wheel house by about 9mm and is concealed internally by the wheelhouse roof lining (not in the kit) and by the large 'Swan Neck Vent' externally.

Good luck with the kit!! DO NOT rely on the templates as they are NOT all correct. Make card templates based on theirs and test fit before cutting. The fittings are 'commercial,one size fits all' and not to scale. I ended up making most from scratch, if you just want it to be a straightforward 'kit build' then it works, most people at the pond will not know if it is scale or not. The hull markings are also wrong, the 'Thwarts'…think thats what they are called, the cut outs that let the water run off the deck, and the Hawser holes are not as full size and look so wrong having been on board the full size. I made the mistake of cutting them out before my visit to the tug and have left them rather that try to fill it all in and start again, lazy I know, regret it now but once again the majority will not know that it is wrong. My model is not to scale, just 'if it looks right then it is'.

have a look at http://www.marinetraffic.com, search for the Portgarth, it is based in Avonmouth now…was Swansea when I went, there are photos there which may help. I have loads taken on board, including the control desks, too many to put on here. I could make up a folder if you let me have your email.

took me 14 months to build, almost full time, good luck.

Regards

Mike

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