Centurion #18

[Adrian Harris]

Glad you're back on track Kevin

Adrian.

[Kevin Hunter]

Good morning all. Can anyone please assist with a couple more small teething problems?

The recoil action was sorted..... but not under load. It worked perfectly with the brass recoil tube attached to the servo, but the minute I screwed in the barrel - no joy.

Much elbow grease and a few sheets of wet and dry later, I managed to get the recoil to work with just a single (rear ) barrel section, but if I then screw in the outer barrel section, it sticks again.

Do I simply need to expend more elbow grease? Is this normal? Anyone else had trouble with the barrel binding in the recoil bush?

Secondly - having trouble with the elevation motor. OK, so I did get the wires mangled in the turret turn cog but all repaired and a circuit tester confirms that the leads to the motor are good. However, selecting up/down on my TX does nothing. Is there perhaps a fuse on this circuit somewhere which might have blown when the wires chewed through and shorted?

So nearly there now - hope the answers are straightforward.

Many thanks

Kevin

[Adrian Harris]

The Recoil Unit is quite sensitive to the the barrel sticking in the tube, and also any slack in the linkages which would allow the barrel to twist. See if the reoil works with a finger supporting the end of the barrel.

When you switch on the Power Supply module, there should be five LEDs glowing red. One at the end next to the 5V supply for the receiver and the others situated one between each pair of power outputs. If any are not glowing, then that fuse has blown.

The Auxiliary Module should be plugged into the middle pair of connectors, and has a 20A fuse.

Adrian.

[Kevin Hunter]

Thanks again Adrian. I'll persevere with the recoil and see what I can do.
Thinking about the fuse, if it's at power module level, then everything downstream of there would be dead? (In this case anything driven by the Aux module?) As the turret turn motor works I'm guessing it isn't a fuse in the power module......
Kevin

[Adrian Harris]

> then everything downstream of there would be dead?

True.

I which case I would:

1) Test the motor on the traverse supply, to make sure the motor turns.

2) Check the limit switches and their connections, as they are there specifically to stop the elevation motor from turning, which is the behaviour you are experiencing.

It could be something as simple as a broken wire, or as odd as the connectors being on the wrong pins on the switches. If they are being used just to sense the limit of travel, and they're on the wrong connections, then the poor old Aux Module will think the gun is both raised and lowered at the same time and won't know what to do...

Adrian.

[Kevin Hunter]

Hi Adrian.
5 red LEDs shining brightly in the power module.
Re the limit switches, are the connections critical? Mine are connected on the two outside spades of the three, but both wires are black.......
Have yet to try using the traverse power on the elevation motor, but that's another useful idea so thankyou. Wondered if I could also test for current at the elevation connector plug with my circuit tester? It's very basic but set to DC (so not giving current itself) shouldn't it register when stick moved on the TX?
Still no joy with recoil. Tank is due out in public on Wednesday and Thursday so looking like that will have to wait. Have painted the barrel now..... However, I did wonder how critical battery level is for the recoil? Mine were fairly low, not flat, but does the servo have more oomph on a full charge?
Cheers for now
Kevin

[Adrian Harris]

> 5 red LEDs shining brightly in the power module.

So that's OK.

> Re the limit switches, are the connections critical?

Yes

> Mine are connected on the two outside spades of the three, but both wires are
> black.......

Assuming that means there is an unused spade between them, that sounds correct.

> Wondered if I could also test for current at the elevation connector plug with my
> circuit tester?

Better to test for voltage. A meter set to measure current is effectively a short circuit, so better to have it set on voltage instead

> It's very basic but set to DC (so not giving current itself) shouldn't it register
> when stick moved on the TX?

Yes. It might be worth seeing if you can operate one or both of the switches whilst operating the stick. Have you checked the connection between the receiver and the Aux unit ? Could one of the plugs be misaligned/backwards ?

> However, I did wonder how critical battery level is for the recoil? Mine were
> fairly low, not flat, but does the servo have more oomph on a full charge?

The servo runs from the 5 volt supply provided by the Power Supply module, so as long as the batteries are above 7 volts, it shouldn't matter how discharged they are. If the servo can affect the batteries, I doubt anything else would work

Adrian.

[Kevin Hunter]

Occurs to me that if I can test the elevation motor using the traverse power supply, then I can do the reverse, ie test the elevation power supply on the traverse motor. That saves any confusion over measuring current/voltage

[Kevin Hunter]

I knew it had been a while since I posted anything about my Centurion, but had no idea it has been almost a year?? I did post about the smoke unit fire, but that must have been in a different section.

Anyway, all up and running again. New power module installed and extensively re-wired. Still having trouble with elevation, but I‘ll get there eventually.

The Cent has been out in public once this year at a local hobby and craft fair attended by Guernsey’s small engineering club. Despite being advertised as a “Geek Weekend” it was well attended, and the tank had a lot of attention from both young and old.

After months of inactivity I finally gritted my teeth this weekend, set to and made a turret basket. I’ve not silver soldered before so my progress wasn’t without some colourful language, and the end result isn’t entirely pretty. However, all said and done, I’m very pleased with the outcome.



I have to thank Ray Brown for his pattern and for showing the way with his own build photos, and Stephen White (plus Australian friends) for the numerous 1/1 reference photos posted on the forum.

Next up, the mesh. I’m sure I read somewhere on the forum that approximate scale would dictate holes 10mm wide by 5mm deep? I found a sheet of anodised (?) aluminium mesh at my local B&Q which I reckon fits the bill.





Next problem – can I solder aluminium mesh to my brass frame……..?
Cheers for now
Kevin

[Stephen White]

Kevin, welcome back. Your IR basket looks the business. The Australian Cents sported at least two sorts of mesh. This was the most common:



Experience in Vietnam suggested a stronger mesh, which was introduced after the tanks came back. I'm not sure if it was also used on tanks in British service:



I've looked at the B&Q mesh and it looks OK. I'd struggle to achieve a join between brass and aluminium by soldering, not least because at the temps needed for ally brazing, the mesh would long since have melted away. I'd suggest you rely on a two part epoxy, with maybe some fine wire binding.

Hope you're laying plans to bring her over for the Bovington show in October - the more Cents the better, now that all these Tigers are around....

All the best.

Stephen

[Ray Brown]

I have to thank Ray Brown for his pattern and for showing the way with his own build photos, and Stephen White (plus Australian friends) for the numerous 1/1 reference photos posted on the forum.


No problems. It's good to help.

Cheers
Ray

[davidwilkins]

Hi Kevin

Good to see you back on the forum, nice job on the turret basket you have made a much better job of soldering than I did. well done.

David

[Stephen White]

Kevin, I'd forgotten we did a full thread on the turret basket and at the bottom you'll see a link for a supplier of mesh which is more accurate than the B&Q offering:

http://armortek.co.uk/Forum3b/viewtopic ... 60&p=40606

All the best. Stephen

[paul&robinmargle]

Despite being advertised as a “Geek Weekend” it was well attended, and the tank had a lot of attention from both young and old.

Don't you know, being a geek is cool now

Robin

[Kevin Hunter]

Stephen and David, thank you both for your kind comments. My soldering isn't great but I'm hoping that once the basket is cleaned up a coat or two of paint will hide the worst bits. And Stephen, yes I was following the thread you refer to - just missed the link re the mesh at the bottom. Thanks.

Hi Robin. I dint know that. What I know about being cool you could fit on a postage stamp

Cheers

Kevin