StuG III 014 - A Team Effort

[Darren_Hagarty]

Hi Peter,
The motors are stiff to turn but with a rag on the drive sprocket it can be done.
The motors are Parvalux and I did send the noise sample to them but they hadn't heard that before. Note they only supply the electric motor not the gearbox connected on the end of it.
I picked up two 12V 18AH Lead-Acid Gel Batteries(Century) today to try, they are charging now.
I also had the final drive housing down as an item to pull apart and inspect the bearings as you say, I've not done that yet though.

[Darren_Hagarty]

Battery Testing

I've just tested the two 18AH Lead-Acid Gel batteries today replacing the LiFePO4 batteries. The test was short but the intermittent engine/gearbox noise is still present with no apparent change. Single track rack turns did not produce the noise as before. I had to cut short the testing due to the weather.

[Peter Silcock]

Darren I wonder whether this noise will fade away as the model is run in. Since you have examined most components and found no evidence of damage perhaps the best approach would be to continue to run it as it is. One thing you might try is to spray all the running gear tracks gears wheels etc with a large dose of lubricating oil such as WD40 if you can get it over there.The only drawback might be slight staining of your paint on the hull if you have not lacquered it or dust and dirt sticking to the oil- clean off after testing. I know you are probably sick of hearing it but the nature of the noise sounds exactly like the tracks catching if the noise does not appear running the model on a large flat smooth surface it can only be deflection of the suspension and track causing the issue. ONE final shot in the dark could it be torsion bars rotating in their housings. Thats me out of ideas.

[Darren_Hagarty]

Drive Motor Gearbox Checks
Since the battery was eliminated as a cause of our intermittent high pitched noise issue the focus went back on the Drive motors particularly the gearboxes and the slip they seemed to have. I had some friends have a look and they said there was too much movement. We checked the gearbox on the end of the electric motors and found no obvious wear or metal filings. There wasn't very much grease though. The bearings seemed to move OK. We replaced a brass shim (washer) which was about 1.2mm thick with ones that were 1.4-1.5mm thick. We also put some extra grease in. The mod reduced the backlash in the drive gear.
We reassembled and tested again and found the high pitched sound was gone and occasionally if we had differential load on the motors we'd get a low pitched growl which could be passed off as normal drive train noise if you didn't know any better.
We don't think its a 100% solution but enough to progress with as there doesn't appear to be any undue wear on the drive cog.
We put the fighting compartment and rear deck on and took a couple of YouTube video's.
There's a fair bit of background noise from birds and the kids so its hard to hear any drivetrain noise. We still have accessories to mount but we won't do that until we do a final spray paint with a dark yellow and red brown camo pattern.

Next we'll try the Amplifier card again this time with the Spectrum RC. All going we'll post a YouTube of that so you can hear the engine noise. After that's its the gun slew/recoil/elevation motors.

Also we've found that sometimes the grub screws on a torsion bar will let go. The only workaround we've found that seems to help in that regard is to back off the screw on the outside of the hull that holds the fixed end. Having that screw 100% tight seems to make the fixed ends more likely to let go. Due to the small size of the grub screws there's only so much force you can apply when using a 2mm Allen key. So if anyone has any tips on the torsion bars and grub screws that would be appreciated.

[Stephen White]

Darren

May I suggest you file a flat on the fixed ends of the torsion bars and then replace the grub screws with socket set screws, which will allow you to nip them up tight with an Allen Key. I've had absolutely no slippage on my Pz III. Secure the set srews with a low strength thread locker, such as Loctite 243.

Best regards.

Stephen

[Armortek]

Darren

As we have previously advised you by e-mail, it is extremely inadvisable for users to disassemble the high efficiency gear box. Increasing the thickness of the shim washer, will have changed the pre-load on the gearset. This will have reduced back lash but significantly increased wear on the gears. In the circumstances we can not guarantee these gearboxes will have a normal service life.

Reference your comments re the suspension, we strongly recommend that other builders do not follow this route. The screw that passes through the hull and into the fixed end MUST be fully tightened.


Mark

[Paul Morris]

Darren.

As Stephen has said a flat should be ground onto the torsion bar ends ... also something I do when using the provided grub screws, I fit the screw onto an old allen key driver and power file a flat onto the bottom of the grub screw then you get two flat surfaces face to face not had any slip yet.
Cheers Paul.

[Darren_Hagarty]

Hi Paul and Stephen,
Thanks for the tips on the torsion bars it certainly makes sense. Our torsion bars already had an angled flat at either end, which we roughed up a bit with a file on the last couple that let go. If we have to reset any more we've definitely file down the bottom of the grub screws a bit and also try using some thread locker.
It would make sense if these tips made it back into build notes to benefit other builders. Maybe by having a PDF of the build notes that could be sent to builders as fixes are discovered.
As far as the motors go it would be interesting to hear how other Stug builders go, hopefully they have a bit more luck than we have. Steven Snel started a forum for his Stug but we haven't heard any more from him since his last post. Steven it would be great to hear from you again.

[Darren_Hagarty]

Amplifier Module Testing
The Amplifier module has been added and tested OK. See attached YouTube video. The sound card volume is still set low during the speaker run-in period (10 hours).


We tried a few different layouts regarding the module layout in the hull. One issue with having the larger modules like the Amplifier module and Auxiliary module vertically mounted in the centre of the hull is that the wires protrude higher than the hull side. When the fighting compartment goes on its flush with the top of the hull and protrudes inside the hull and crushes down on the cables.
So we put the Amplifier module and Auxiliary module further back so they are under the rear deck which sits higher than the fighting compartment at the sides. The modules are just blue-tacked to the side of the battery. Whenever the battery needs a charge we just pop the modules off the battery.
We also didn't mount the motor control module between the motors as we found that made the power cables to the motors inaccessible without removing the module.
The speakers were mounted lying down which projects the sound upwards and also because they are too tall for the fighting compartment if mounted vertically.

Next step is connecting the slew and elevation motors in the fighting compartment.
If anyone has any photos of the limit switches in place that would be useful. Also we're not sure how the gun recoil is supposed to work we can't find any mention of that in the guide. So if anyone had any tips on that it would be appreciated.

[Darren_Hagarty]

Mounting Slew and Elevation Motors
Mounting the Slew, Elevation Motors and Elevation limit switches wasn't too hard we had to replace some of the supplied fasteners for ones that fitted. Both motors are the same. Where ever the guide mentioned turret turn motor we applied that to the Slew function as of course the Stug doesn't have a rotating turret.
So far we've only tested the Slew motor and have used the rudder channel on the left joystick. Using a switch produced too much speed in movement. See attached photos and video of Slew motor in action.
Next we plan to try and set the limit switches and see if we can get the Elevation motor to work.
YouTube of Slew Motor in action.

[Darren_Hagarty]

Testing Elevation Motor and Limit Switches
The first issue we had here was one of the limit switches was incorrectly wired out of the parts bag. The Limit switches have three possible connection points, two at the back and one on top (Common). You always need the common wired and either one of the other two connections points (giving normally closed or normally open). The metal finger closes the micro switch depending on the position of the finger.

Note the guide had the correct wiring connections so if you followed that you were right.
The one we had a problem with was wired with the two rear connections. (See photos for correct wiring).

We used the Aileron control on the Spectrum DX7s for the Elevation control.
The inside limit switch controls the up elevation and the outside limit switch controls the down elevation. Setting the outside one was the hardest as it contacted the conrod going the to top of the Slew motor. The conrod is narrow and can move so it required more tuning to set that one.
The up elevation switch is normally closed so it cuts out when the micro switch is depressed. The down elevation switches is normally open so the micro switch needs to be depressed for motion to occur. Once the finger loses good contact with the conrod it released the micros switch an motion stops.
If you listen closely to the sound in the YouTube video you can hear the micro switches clicking on and off.



Next challenge is the recoil kit.

[Armortek]

Hello Darren

Maybe someday you will come across something that you consider to be correct, but somehow I doubt it.

Mark

[Chris glover]

[michael hilton]

Back of the net......Mick

[Stephen White]

This is a wonderful community of like minded folk, enjoying the best engineered and produced one sixth scale models available anywhere. When I post, I try to add value with things which I think will interest and sometimes amuse and there are lots of times when I ask for advice, which is always freely given. I try not to advertise the occasions where I've failed to read the instructions or where I've cocked up through my own lack of expertise. Were I ever to find something which I think Mark and Gill could improve, I choose to email them privately or ring them up and I've unfailingly found them receptive and welcoming. Nothing is perfect but Armortek come very close. Food for thought?

Stephen