Early Tiger 1 from sPzAbt 503

[cahlfors]

Today's testing has yielded that 15s is all it takes to go from cold to having the smoke chamber completely filled with thick smoke. Much faster than I thought!
Then, reducing to half power is about right to maintain the thick smoke in the chamber. Hopefully, that's enough to be safe. Maybe I should turn the preheating off completely if I forget it totally?

Anyway, nice to have everything software controlled. No disassembly, no rewiring, no soldering, just add a bit of program logic and there is a new function - it's already done - nice!

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[Björn Johansson]

Looking forward to see it in action IRL , Nice videos

[cahlfors]

New, larger, speaker boxes have been made and new, larger, bass membranes installed. Oh, the speaker elements are new, too. The old coaxial elements were not airtight and so their bass membranes had zero effect. The new ones are mid basses, totally lacking higher frequencies. I was worried about how that would sound, but it's no problem at all.

The old, leaking, three-way speaker was reasonably loud, but was seriously lacking in bass:

The new, airtight, mid bass has a slightly larger box and a much bigger membrane. It also has a much higher quality speaker element:

The new speakers at work:

https://youtu.be/rSWrVSeWJKo

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[mrTyko]

Nice Christoffer.
I see that I definitely have something to work on to surpass you.

Robert

[cahlfors]

The speakers do their job nicely, but the sound system would benefit from some improvement. There is some LF noise and the sound drops out at times. I suspect that moving the volume control potentiometers from the Arduino addon board would improve that.

The latest development has been fixing the drive system after Linköping, when there was significant noise from the gears. When I opened up the final drives, they looked like this:

This is not the result of bad parts, but of one accident and bad advice. About ten years ago, one motor had come loose. I didn't notice and drove along, but the gears meshed at a slight angle, which damaged them. I had the final drive apart last year or the year before that and after cleaning up, I lubricated them with PTFE dry lube, per the manufacturer's instructions. That was a bad idea. The problem was exacerbated and the gear teeth totally wore out, as seen in this picture:

The gouging in the hull is because of the deformed gear teeth. New gears have arrived and I figured that maybe a support bearing on the pinion shaft would help with gear alignment after removal of the motors. Like this:

Suitable bearings were expensive, but you only need two per model. A bushing was needed on the motor shafts, like this:

The motor mounts needed touching up slightly in the lathe, in order for the support bearings to slip in easily:

The finished motor with new pinion and support bearing:

Here, the motor is installed in the model. The support bearing shows between the gear teeth:

I'm not sure there is any flexing, necessitating a support bearing, but there has been gouging in the final drive case by the pinion. It either comes from the shaft flexing or not ending up in the exact same position after reinstalling the motor. It COULD also just be a result of the pinion increasing its diameter when wearing out and the teeth get narrower, but possibly taller. Either way, the margins are small. The surface, gouged at the bottom, is inked blue for later inspection:

The model operated well at the latest show, but removing the motors just to check the gouging requires removing the battery cells as well.
However, there is still some noise on the left side. Potentially, the internal gears in the gearbox are damaged/worn out. They have lasted 13 years of enthusiastic driving, so maybe that's satisfactory, although unexpected.

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[cahlfors]

My good friend MrTyko made new side skirts in the correct length out of brass. The square headed nuts on the hull to hold them have been relocated to suit.

It was now time to make the wedge shaped stiffeners on their rear. I decided that using shears and filing would be very tedious as well as hard to get right. Instead, I had a go on routing on the CNC mill. I always wanted to test that and this was a good opportunity. I think it's great fun to watch the machine making parts much better than I could possibly do by hand.

https://youtu.be/WLGKpd3AnBI


I tried with holding tags first, but that didn't work out very well, so decided to skip those. That's why the parts come off and lie all over the place.

Here are some supports, along with 3D printed tests, to check the fit:

The supports soldered to the side skirts:

The completed side skirts mounted to the hull:

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[mrTyko]

Beautiful Christoffer, and thank you for a nice teamwork.

Robert

[cahlfors]

I have found the most probable reason for my sound cutting out intermittently in Hässleholm and Denmark:

The power amplifier draws significant current. Its fuse holder in the A-tek power module made poor contact with the fuse, leading to oxide and pitting. This was very simple to correct: A bit of 5-56/WD40 (to remove the oxide), a squeeze of the fuse holder contacts with a pair of pliers and a new fuse.

I had previously suspected the 24V feed voltage to the Benedini TBS5 sound card. It is way beyond the 12V spec of the card, but okayed by Thomas B himself. The problems have seemed to come with prolonged operation or direct sunlight. Heat in other words. If the card is fitted with a voltage regulator, there would be more to dissipate with 24V and could potentially be problematic with sunlight or high surrounding temperatures. For this reason, I have moved the card over to a 12V converter I now have in the model. This won't hurt, but I really think the direct cause of the cutouts was the fuse holder.

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[mrTyko]

Excellent work finding this error.
I will now check this in my tank.

Robert

[cahlfors]

I have finally had an appointment with the body shop after a fender bender in 2015, when Nafets' bridge hit the tiger from behind.
But it was a quick bridge, I promise!

Unfortunately, I don't have any "before" pictures, but the solder joints were broken, with the parts bent and one flap had broken off at the hinge.

Step 1, lacquer removal:

Step 2, reinforcements desoldered and straightened out:

Step 3, application of silver solder:

The idea is that instead of tin joints breaking and the whole thing having to be disassembled and redone, maybe a silver joint will hold and you only need to bend it back to shape?

Step 4, reinforcement embedded in solder paste, ready for heat:

Step 5, it's not pretty before cleaning. What have I done!

Step 6, I ran out of citric acid, so the oxide didn't quite come off:

Step 7, a steel wire brush was useful to clean off the worst:

Step 8, an abrasive rubber wheel was good for the corners:

Step 9, after that, I managed to gather some citric acid to cook a weak acid solution to clean some more oxide and then on with some polish and a polish wheel. The remaining polish got dirty...:

Step 10, cleaning in detergent and alcohol made it clean and shiny, ready for assembly and a clear coat:

Step 11, assembled an installed in place. The fixed part of the hinge is also not quite straight after the bridge encounter, so the flap looks kind of crooked, but that will have to be a later project:

The end result:

All these little things that need to be fixed can take quite some time before they get done. The model hasn't looked like this for many years!
I gold plated one of the fenders while I was at it - can hardly tell the difference...

It's interesting that all the pictures got turned to the side when uploaded.

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[Hans K]

Double-click the image and it will be right-sided.

Hans K

[mrTyko]

Nice with a continuation of the solder school from Cahlfors.


Robert