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Author Topic: Queen Mary  (Read 56326 times)

carlmt

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Re: Queen Mary
« Reply #125 on: February 20, 2017, 11:14:24 pm »

Hi Ken - re the motors....
 
I don't know the full specs of your model (weight, draft etc.), but our Norland prototype weighs in at about 13.5kg (nearly 30lbs) and moves very well with a couple of 555's spinning 40mm brass Raboesch props on 12v.  I don't know if there is enough room in your hull for the number of 555's you would need, but they are slowish revving motors with plenty of torque.
 
Just my observations....
 
Carl  :-))

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Re: Queen Mary
« Reply #126 on: February 22, 2017, 10:59:31 am »


Thanks for input Carl.  It looks like 500 series route for me.

That could be sometime off as I am now up to  'Plating the hull'.  I have the details of every rivet and plan to spend some time getting them in the right places.....  My new  'Specs'  have been built and paid for  (wow)  and I can see better than ever now.     :}

Here are the latest hull flattening pictures.  Please don't go on the colour arrangements as she is flat all over which is ideal for the plating to be fitted and the half million rivets yet to be done.


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cos918

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Re: Queen Mary
« Reply #127 on: February 22, 2017, 07:18:43 pm »

HI Ken
My Finnjet ferry is running 550 motors on 12v on 40mm props X2 . She can go slow and has a good turn of speed . These would work very well for you as a 35 mm prop would reduce load and current pull . Carl mentioned the 555 which also would work well. Note when buying a motor check out the specks as there are several version of each type of motor. Here is a link to two 555 motor . the specks are not the same


john


 http://www.robotshop.com/uk/rs-555-12v-7750-rpm-brushed-dc-motor.html
http://www.componentshop.co.uk/mabuchi-555-dc-motor-mounting-bracket.html?___SID=U
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Re: Queen Mary
« Reply #128 on: February 22, 2017, 08:47:29 pm »


Thank you for info John.

I have been over to see the site.  I have bookmarked my  'basket' and am seriously thinking about this.  What's their delivery system like for time of arriving please.

ken
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carlmt

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Re: Queen Mary
« Reply #129 on: February 22, 2017, 09:07:35 pm »

Mine are the Mabuchi variety from Component Shop  :-))
And delivery is usually next day from order - if ordered at a sensible time of the day obviously!

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Re: Queen Mary
« Reply #130 on: February 22, 2017, 09:28:42 pm »


Thanks Carl.  Their price seems to more than twice the other company's.  I probably won't be sailing much and as I need 4, this would make it an expensive business.  I also have to order 4 props and matching shafts, and we all know how expensive these are.

I'll let you know how I get on.

ken
 
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Colin Bishop

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Re: Queen Mary
« Reply #131 on: February 22, 2017, 10:26:24 pm »

While 4 motors and 4 props is the conventional solution, an alternative option might be to use belt drive with 2 motors each driving 2 shafts. It has been done before.


Colin
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Re: Queen Mary
« Reply #132 on: February 23, 2017, 09:29:03 am »


Colin.  I do like that idea.  It would reduce the  'back end'  weight as well.

Does anyone know where might I get this 'gear set up' please. ?

Cheers

ken
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plastic

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Re: Queen Mary
« Reply #133 on: February 23, 2017, 09:52:23 am »

The QM propellers were 20' diameter so that equates to 30mm @ 1/200 scale.

Why not just go low tech with 4x 385 motors driving long 2mm shafts via rubber tube couplings with 2 speed controllers driving 2 motors each? You can get them down low in the hull and silicone them in for simplicity. A 6V SLA  gives ballast and long endurance.

The motors are a couple of quid on ebay and it's a simple installation without mucking about with belts in confined spaces.

They provide plenty of power - I have only 3 driving my 1/200 Titanic perfectly well.
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Re: Queen Mary
« Reply #134 on: February 23, 2017, 10:11:47 am »


Thank you for the input, plastic.

I've just been looking at gears and decided it was overkill.  I'm thinking of just two motors now and having the other two props free-wheeling.  (inside or outside ---- which is best)
 
The idea is to use 12 volts throughout the ship so I should have a bit of spare  'power' as a get out of trouble system with larger motors.

Now working on the  'plating' and have succeeded in slicing the top of my finger with the Stanley knife  (again !!)  That will slow me down a bit.   %)

Back to the TV watching.

ken

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Colin Bishop

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Re: Queen Mary
« Reply #135 on: February 23, 2017, 04:59:14 pm »

Ken, if it is possible to teminate all the shafts at the same position within the hull using different lengths for the inners and outers then you could mount pulleys on each shaft and link the two shafts on each side together with an elastic driving band. Then just drive one of the shafts on each side with a motor.

If you choose to freewheel it is difficult to advise. The inner shafts will be more responsive to the rudder, the outers will be better for tank steering responsiveness.

Colin




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plastic

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Re: Queen Mary
« Reply #136 on: February 23, 2017, 05:14:26 pm »

Ken, if it is possible to teminate all the shafts at the same position within the hull using different lengths for the inners and outers then you could mount pulleys on each shaft and link the two shafts on each side together with an elastic driving band. Then just drive one of the shafts on each side with a motor.

If you choose to freewheel it is difficult to advise. The inner shafts will be more responsive to the rudder, the outers will be better for tank steering responsiveness.

Colin


I'd be careful about that - At 1/200 scale, 2mm propshafts are about the right size. Rubber band drive cannot transmit a lot of torque unless the band is very tight - which will but a huge side-load into the shaft bearings causing leaks or premature failure.

Toothed belts would better but still put a huge side-load on the shaft.
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Colin Bishop

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Re: Queen Mary
« Reply #137 on: February 23, 2017, 05:32:34 pm »

Just about all my boats use plain belt drive and always have. Never had a problem with it whether 2mm or 4mm. No need to make the belt too tight, it just increases power consumption.


With a motor to shaft drive the tension can be adjusted by slightly moving the motor mounting. Between two shafts you can introduce a small adjustable tensioner pulley.


The whole point is to turn the drive pulley, not tug it against its bearing. Works OK on millions of car fan and accessory belts, works on models too!


Colin
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cos918

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Re: Queen Mary
« Reply #138 on: February 23, 2017, 07:55:09 pm »

Thank you for the input, plastic.

I've just been looking at gears and decided it was overkill.  I'm thinking of just two motors now and having the other two props free-wheeling.  (inside or outside ---- which is best)
 
The idea is to use 12 volts throughout the ship so I should have a bit of spare  'power' as a get out of trouble system with larger motors.

Now working on the  'plating' and have succeeded in slicing the top of my finger with the Stanley knife  (again !!)  That will slow me down a bit.   %)

Back to the TV watching.

ken


Ken power the outer pair would be best . The cost between 2 motor and 4 motors is not a lot . If i was you I would go for 4


john
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ballastanksian

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Re: Queen Mary
« Reply #139 on: February 23, 2017, 08:22:49 pm »

Go careful Ken, model making is difficult without fingers unless you go sculptural and freeform:O)

For your mammoth rivett-o-thon, are you embossing the rivets into the back of plates before fitting them as adding single ones will be tedious and I fear you would forever be adding replacement ones as and when they are knocked off by annoyingly light impacts.

She is starting to look the part  :-))
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Re: Queen Mary
« Reply #140 on: February 23, 2017, 09:23:01 pm »


Thanks for the inputs fellas.

I plan to use 4mm shafts as the couplings between will present no problems to the motors.   Also I might go with the original idea of 4 motors driving 4 bladed props. There's plenty of room.

The rivets will be punched from the back to produce a line of domes on the outside surface of half m/m plastic sheet. I'm thinking of a parallel bed of blunted nails in a stationary drill press.  Sort of mass production.

 I have today continued with my cutting of the plating into lengths.  Would you believe I used the band saw for a perfect parallel edge.  Much better than a Stanley knife against a ruler.   %)

Cheers
ken

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ballastanksian

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Re: Queen Mary
« Reply #141 on: February 23, 2017, 09:47:27 pm »

I don't blame you Ken as it will be a tedious job even for the most avid modeller. Your embossing tool idea has  merit especially if you make a few of differing lengths to maximise on ease of operation.

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SailorGreg

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Re: Queen Mary
« Reply #142 on: February 24, 2017, 09:08:15 am »


 I have today continued with my cutting of the plating into lengths.  Would you believe I used the band saw for a perfect parallel edge.  Much better than a Stanley knife against a ruler.   %)

Cheers
ken


Yeah - four fingertips in one go!   {-)


For producing the rivets, have you considered using a ponce (or pounce) wheel?

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Re: Queen Mary
« Reply #143 on: February 24, 2017, 10:27:20 am »

 
Yes Greg,  automation will have to come into it due to the quantity required. (2000 might not even be enough !)   I am looking into methods at the moment of automating this.  Wheels and power press come to mind.

ken
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plastic

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Re: Queen Mary
« Reply #144 on: February 24, 2017, 02:52:59 pm »

Why not get a sewing machine and grind the needle length until in becomes a dent-maker rather than piercing the material?

There is stitch size adjustment and auto index - you can run a long lengths of material through it and then cut the individual plates from the long length - fully automated rivet plate manufacturing.

It should work great on plasticard or cardboard. Have the whole lot produced in a few minutes.
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Capt Podge

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Re: Queen Mary
« Reply #145 on: February 24, 2017, 04:46:13 pm »

Why not get a sewing machine and grind the needle length until in becomes a dent-maker

Sorry for butting in but that sounds like a great idea O0

Also, the possibility of using this method on litho-plate could be explored. :-)

Regards,

Ray.
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Re: Queen Mary
« Reply #146 on: February 24, 2017, 05:03:40 pm »


Great idea Plastic.  I'm sure the members will pick up on this.

We don't have a sewing machine so I've gone for a 'rounded off' large nail and fitted in the pillar drill.  I've pulled the plug out and set it up as a press.  I marked out a piece of wood for the drill vice and adjusted the throw to just press on the plastic strip without puncturing it.


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Re: Queen Mary
« Reply #147 on: February 24, 2017, 05:09:14 pm »


I then cut loads of half mm plasticard into strips 10 mm wide.  After marking out distance marks I set too and started pressing the dimples into the plastic strips.

I have done 1400 imitation rivets so far and broke off for the day.  I have placed some onto the hull to give an impression but the camera doesn't show white dots on white plastic very well.    :}

I am pleased with the result and when my arm is rested  (muscle ache !!) I shall be back tomorrow for another batch.

ken

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ballastanksian

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Re: Queen Mary
« Reply #148 on: February 24, 2017, 09:04:25 pm »

They show up really well Ken, worry ye not about that.
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Re: Queen Mary
« Reply #149 on: February 25, 2017, 11:06:20 am »


Thanks 'B' ,  it's all interesting stuff. I only need 6000 more rivets  (he says).  I'm certainly going to count them when I've finished.

The portholes will have to be drilled when they are affixed to the hull.

ken
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