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Poll

Which version of the Sentinel would you consider ordering?

SDJR Version
12 (52.2%)
7109 Version
10 (43.5%)
7109 and SDJR Versions
1 (4.3%)

Total Members Voted: 23

Author Topic: Sentinel 0-4-0 Body Kit  (Read 16809 times)

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Offline Bob Tidbury

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Re: Sentinel 0-4-0 Body Kit
« Reply #300 on: July 16, 2017, 09:10:04 pm »
Was the Humbrol.Grass Green Acrylic or Enamel paint please fergy1?
Bob Tidbury

Offline fergy1

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Re: Sentinel 0-4-0 Body Kit
« Reply #301 on: July 17, 2017, 07:55:04 pm »
Hi Bob,
I used the acrylic version :)

Regards

Kevin

Offline Bob Tidbury

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Re: Sentinel 0-4-0 Body Kit
« Reply #302 on: July 17, 2017, 09:20:37 pm »
Thanks mate thats what I hoped you used as Ive been told several times that Enamel can eat the plastic used in 3D printing .
Bob Tidbury

Offline fergy1

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Re: Sentinel 0-4-0 Body Kit
« Reply #303 on: July 17, 2017, 09:27:20 pm »
Hi Bob, I tried using enamel paint with some of the first 3D printed models I purchased but I found the enamel paint never went off. I have managed to use enamel since, but it requires a lot of cleaning and some good coats of primer before it works!

Regards

Kevin

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Re: Sentinel 0-4-0 Body Kit
« Reply #304 on: July 17, 2017, 10:13:58 pm »
FUD has a similar solvent base as turpentine.

Halfords grey undercoat with a good coverage is best to undercoat and acrylic is better than oil based paints.

Offline fisherman

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Re: Sentinel 0-4-0 Body Kit
« Reply #305 on: September 08, 2017, 03:33:38 pm »
Have just uploaded a couple of pics of  my  sentinel to the  gallery
<o({{{<<

Offline AR

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Re: Sentinel 0-4-0 Body Kit
« Reply #306 on: September 12, 2017, 01:15:40 am »
Hello all,

Thanks for the comments!

As some of you may know, I am currently studying abroad for a year, hence the lack of replies!

@fisherman I have just had a look at the photos of your Sentinel and have to say it looks splendid with all those brightly coloured wagons:)

Cheers,

Alex

Offline CarriageShed

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Re: Sentinel 0-4-0 Body Kit
« Reply #307 on: December 06, 2017, 10:17:46 am »
I still haven't got mine done but I've been trying to work on it recently. The motor worked just fine after I fitted the resistor (shown below).



Acceleration was very smooth and slow speed control seemed good. Then I left the motor on my 'workbench' cutting mat for a while as I worked on other projects and pondered a permanent wagon with pick-ups for the Sentinel. Now I've tested the motor again and it won't go at all.

I can see the slightest flicker of activity on the meter when I put a bit of pressure on the motor while its on the track, but there's no motion, forwards or backwards. Something's going in but it's not doing anything. Is it that easy to burn out these things?

Offline CarriageShed

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Re: Sentinel 0-4-0 Body Kit
« Reply #308 on: October 10, 2018, 04:38:18 pm »
It turns out that the resistor was too generous for this motor. I need to work out a better one to use, but that could take some time...

Offline acook

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Re: Sentinel 0-4-0 Body Kit
« Reply #309 on: October 10, 2018, 10:13:25 pm »
WARNING: This post contains electricity AND mathematics!

Run the unit carefully on pure DC not PWM up to the maximum speed you want it to go, and measure the track voltage and current.

Lets say that is 4V and 50mA, which is 0.05A

Using Ohms Law 4/0.05 = 80 Ohms motor resistance.

Assuming the full track voltage is 12V, then for a current of 0.05A the total resistance is 12/0.05 = 240 ohms.

Subtract the motor resistance 240 - 80 = 160 ohms needed.

The power dissipated by the resistor is (12- 4) x 0.05 = 0.4 Watts so good for a 0.6W metal film resistor.

If the power comes out higher, you can use 2 resistors in parallel of double the value, in this case the nearest standard value would be 330 ohms.

Alan

Offline themadhippy

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Re: Sentinel 0-4-0 Body Kit
« Reply #310 on: October 10, 2018, 10:57:27 pm »
 
Quote
Lets say that is 4V and 50mA, which is 0.05A

Using Ohms Law 4/0.05 = 80 Ohms motor resistance.

Assuming the full track voltage is 12V, then for a current of 0.05A the total resistance is 12/0.05 = 240 ohms.

Subtract the motor resistance 240 - 80 = 160 ohms needed.

or   ( supply voltage - required voltage)/ full load current.

Offline CarriageShed

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Re: Sentinel 0-4-0 Body Kit
« Reply #311 on: October 11, 2018, 01:16:09 pm »
WARNING: This post contains electricity AND mathematics!

My brain already hurts. Be gentle with me, although I certainly appreciate the effort. The elektrickery side of this hobby fries my brain on a continual basis. I think I need to have a brain resistor fitted to protect it.

Run the unit carefully on pure DC... up to the maximum speed you want it to go, and measure the track voltage and current.

Lets say that is 4V and 50mA, which is 0.05A

If I'm reading the multimeter right then those figures are pretty much perfect.

Subtract the motor resistance 240 - 80 = 160 ohms needed.

The power dissipated by the resistor is (12- 4) x 0.05 = 0.4 Watts so good for a 0.6W metal film resistor.

If the power comes out higher, you can use 2 resistors in parallel of double the value, in this case the nearest standard value would be 330 ohms.

Alan

If I've got this correct then this is an 0.6W metal film resistor:
https://www.ebay.co.uk/itm/10x-0-6W-1-Metal-Film-Resistor-Axial-All-Values-Multi-Qty/302816132982?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20151005190540%26meid%3Dd64b26e86caa4b7c82cc8bcd66ff8ac5%26pid%3D100505%26rk%3D1%26rkt%3D1%26%26itm%3D302816132982&_trksid=p2045573.c100505.m3226

The body for this chassis is very tight - it's barely possible to get a single resistor in there and even that required some filing of the internal bodywork. If a single resistor is used, would the resistance still be the 330 ohms?

Peter

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Re: Sentinel 0-4-0 Body Kit
« Reply #312 on: October 11, 2018, 01:20:24 pm »
You can use a surface mount chip type.

Offline acook

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Re: Sentinel 0-4-0 Body Kit
« Reply #313 on: October 12, 2018, 12:13:35 am »
160 ohms is the required value when using 1 resistor.

2 330 ohms resistors side by side gives 165 ohms total resistance.

Since my guess was so close to actual  ::) just use 1 160 ohm resistor.

Alan

Offline CarriageShed

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Re: Sentinel 0-4-0 Body Kit
« Reply #314 on: October 12, 2018, 10:15:01 am »
A single 160 ohm resistor it will be then.

This is the sort of quick turnaround, problem-solving help that forums are really good at providing. Thanks Alan :)

 

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