Roy's StuG III (no. 2020/10)

[Tom OBrien]

RE Pins:

The steel pins are designed to be forced into fractionally smaller aluminum holes. Notably, even though aluminum is softer, the steel pins can get bound and then it becomes problematic.

I did what Mick suggests but with only the drill bit, just slightly smaller than the hole diameter, and working it like a file through the first hole plus the hinged piece until the pin would go through without much force. Then, only partially through the opposite hole so the pin can get a start when pressing or hammering.

I prefer to very carefully hammer the pin with the hinged piece in place, placing the assembly on a small anvil to give it proper support when hammering. I used a small tack hammer, not very big. Also, it's important to place the part of the assembly with the hinged holes directly onto the anvil (or more accurately, the edge of the anvil) so when you hammer, it's a solid "assembly-against-anvil" stroke.

From a vice, pressing the pin into the assembly is a good idea too as you can go very slowly, being careful to align the pin at the start. I also used a vice on several pinned assemblies but found that a hammer is just as effective, if properly done.

cheers... Tom

[Roy Beukeveld]

Reading everyone’s feedback on the hinges I realize i could have done something better. Instead of drilling through both parts i could have done one. That way the fitting is less firm and the pin would still be retained.
Although the hinges function fine the way they are now it is something to keep in mind for future occasions.

[michael hilton]

Hello Roy, my hinges or hinge, on previous models, broke with use. If the pin is forced into the softer metal, as Tom said, it binds solid. The cover or door can be opened and will remain closed or open however, with continual usage the weaker part of the hinge, will break.
I cheat, by using a slightly smaller bolt or screw, cut the head off, then seal each open end of the hinge with a smear of araldite adhesive or milliput. The bolt can easily be removed should there be a need.
Do not worry Roy...I learn by my mistakes. With a tight hinge, at the very least the cover or door will not flap about , you are building a fine StuG, I love it...mick

[Roy Beukeveld]

Hello Roy, my hinges or hinge, on previous models, broke with use. If the pin is forced into the softer metal, as Tom said, it binds solid. The cover or door can be opened and will remain closed or open however, with continual usage the weaker part of the hinge, will break.
I cheat, by using a slightly smaller bolt or screw, cut the head off, then seal each open end of the hinge with a smear of araldite adhesive or milliput. The bolt can easily be removed should there be a need.
Do not worry Roy...I learn by my mistakes. With a tight hinge, at the very least the cover or door will not flap about , you are building a fine StuG, I love it...mick

Hi Mick, I think time will tell if they will hold or not, removing the pin now in an attempt to modify them is probably not a good idea so I'll have to leave it this way. Risks of being an Armortek first timer And thank you for the compliment!

[Roy Beukeveld]

I'm getting near to the point that I can set my wheelarms to the right angle. I have determined the component layout so when the angles are set the model can be checked for standing level on the road wheels.
As discussed a couple of posts back, the concern is if the fixed ends will hold.

...After the pre-assembly I drilled with a 1.6mm drill, then drilled a recess with a 2m. grubs with a point were used. this could be screwed into the recess...

I made an addition to the solution provided by Florian, I drilled a 2,8mm hole through an M5 bolt on the lathe.
Plan is to set the angle properly, tighten the countersunk screw firmly. Instead of the grub screw I will place this drilled through bolt in.
Than with the Dremel drill through this bolt a few millimetres into the fixed end. Then remove this bolt and place a grub in with a point head.
This way the hole is drilled exactly centered and the angle should remain perfect when the grub is placed in.



I ordered the pointed grubs so that will be next week.

[Tom OBrien]

Roy,

Your plan sounds like a good solution, so long as you leave enough metal in the torsion bar after drilling into or through it. A weakened bar will eventually break after so many torsion-like twists at the point where you've drilled into it.

The bar is 5mm dia., which will leave 1.1mm on either side if you drill a 2.8mm hole. I cannot be certain without the proper tests but this might be enough so that when pinned, the bar will withstand the repeated side ways torque or twist. And it will guarantee the bar will not slip.

I don't have a lathe so my solution was to sink a 3.5mm hole or depression only about 1- or 2mm deep into the torsion bar at the point where I wanted to secure the grub. I replaced the M4x4 grubs provided in the kit with longer M4x6 grubs. The replacement grub's added length along with the drilled depression in the torsion bar, helps assure a more solid connection between the torsion bar and the piece through which it is mounted. The longer grubs also help prevent its threads from stripping when you tighten them.

Also, when tightening the grub screw into the depression in the torsion bar, I found it helps to wiggle the swing arm slightly while tightening. This helps settle the grub more directly into the depression in the bar.

Notably, I did this with only one of the two grub slots for each bar, leaving the original M4x4 grub in its place. I believe this should be enough to do the job.

Once satisfied that the M4x6 grub is properly set, I used thread lock BLUE to finish the assembly.

Sorry for the long explanation. Maybe it's time to learn how to take pictures -- pictures are, after all, worth a thousand words.

Cheers.. and happy new year!

[Roy Beukeveld]

Hi Tom,

The torsion bar ends in part CL0222 (Fixed End). The method I described is ment to fit in the position of the M5 grub (see picture below).
From there I drill a small hole in the fixed end, only the fixed end. So no weakening of the torsion bar.
Then a grub with a point head is placed and the fixed end can't rotate in any way.

When I look at the drawing below, it also shows that from the M5 grub position drilling through probably will go passed the end of the torsion bar.



What you describe is the rotation of the torsion bar in the fixed end. I must say that the thing that got me most concerned was the unwanted rotation of the fixed end. I was under the impression that the M4 grubs against the flat on the torsion bar would hold it tight enough in place.
So now I'm wondering after reading your message if I should do that as well. And if I would, it should also be applied on CL0205 (suspension shaft).

Food for thought...

[michael hilton]

Hello Roy, with reference to the fixed end. Before you make these changes, in my experience and for what it's worth. Unless you are going to run your precious StuG beyond reason...then the fixed end will do just what it says on the tin...remain fixed. Again, and this is only my opinion, these models build and operate perfectly fine, 'out of the box''. if you will use and run the StuG aggressively then belt and braces is the way to go, otherwise they are perfectly fine....again only my opinion .....Mick

[Roy Beukeveld]

Hi Mick,

It’s very useful to hear your experiances, as this is my first model i obviously don’t have them yet
But locking a torsion moment by friction is a method that does raise some concerns.

The remark that these kits run perfectly fine out of the box is ofcourse comforting and to be expected seen the overall quality of the kit.

I do think I will replace the M5 grubs with the pointed ones, it is a minor modification, perhaps an unnecessary one, but i see it as an extra reassurement.

[Tom OBrien]

Roy,

I finished my StuG and have set it aside to wait for the sound and motion packs to arrive -- no word from Armortek when they plan to ship them.

MEANWHILE, relating to the discussion on TORSION BARS, over the past year and a half or more, I've been experiencing tracks that would ride up onto the front set of road wheels of my Tiger I. The wheels, including the idler and drive sprockets are perfectly aligned, and I've tried adjusting the track tension from very loose to overly tight, with little if any effect.

After jacking the Tiger up onto it's motorcycle scissors jack platform, I discovered that the front road wheel tension bars have come loose from the swing arm (wheel) side of their housings, meaning the grub screws holding the torsion bars in place have failed. Either I could not tighten them sufficiently when installing them without stripping the 4mm grub screw sockets, or the thread lock I used had allowed the grub screws to back out, or both.

So now, I've gutted the Tiger of it's electronics, batteries, etc. and will begin to perform a series of operations to re-work the torsion bars that are problematic. It all reminds me of the importance of setting the grubs at the beginning of the build so you don't have to go back like I'm doing now and fix them.

Cheers... Tom

[Christoffer Ahlfors]

The torsion bar system is indeed problematic. Grub screws biting into a thin bar are really not up to the job. My Tiger 1 torsion bars often come loose from the fixed end. On closer examination, the moving end is equally problematic. Ideally, the system should squeeze around the torsion bars instead. That would be a lot more powerful.

However, my tiger 1 still runs great despite all this. There were plenty of issues in the beginning and I was hunting like you were. I found out that tensioning the track does not solve climbing issues (quite the opposite, in fact...). Prototypical track tension is far too tight. When all is right, a very slack track will still ride well. I found these things are critical:
1 Chamfering on the sides of the sprockets.
2 Chamfering on the front and rear of the sprocket teeth.
3 Centering of the sprocket teeth in the sprocket holes of the track links.

Pick a nice summer day (or suitable place indoors, if you have a mansion...), lay down on the ground or floor and observe where the sprocket teeth enter the holes in the track, turning both left and right. Forward and backward. You want them to be as centered as possible. This leads to adjustment of the sprockets on their shafts to get the alignment right. Take note of the distance from the sprocket to the hull, for future reference, when you are happy. This David Attenborough approach will also reveal if your chamfering is right, so that the sprocket teeth slip nicely into the holes, or if they catch, causing climbing.

Every model will have its specific issues with this, but the basics should be the same. The secret is the close observation of what happens when the sprocket teeth meet the track.

Good luck!

[Tom OBrien]

Roy,

Thank you for that detailed description as it helps me think again about the sprockets. The torsion bar suspension might not be the problem I'm experiencing but while I have it taken apart and up on a jack, I'm going to re-visit the alignment, sprocket chamfering (I chamfered but perhaps not enough), and the positioning of the sprocket on its drive axle to make sure the tracks are as perfectly centered as possible. (Although, I realize the tracks should be viewed when on the ground with the full weight of the tank upon it).

I've been dulling drill bits in my attempt to drill small holes or depressions into the steel torsion bars, so visiting the hardware store will be my mission for today.

How is your StuG progressing? Have you decided on a method for quickly and easily securing the top deck and gun platform to the hull?

cheers... Tom

[Roy Beukeveld]

Hi everyone,

The torsion bar system is indeed ....... sprocket teeth meet the track.

Thank you Christoffer for giving directions on this issue, I am not up to the point yet where I can test the track but when I am and run into some issues there I will remember your post.

Roy,

Thank you for that detailed description as it helps me think again about the sprockets. ...

Tom, credits to Christoffer

... How is your StuG progressing? Have you decided on a method for quickly and easily securing the top deck and gun platform to the hull? ...

Well I must say, first week of the year has been a busy one, so not much work done. This afternoon was my first opportunity to work on the StuG again so little progress.
What I did achieve was locking the fixed ends in place by the method described earlier, with the drilled through bolt.



I set the suspension to the proper angles, and tightened all bolts very firmly. Tested it with all the weight on and it looked perfectly level.
From there on stripped it all off again, and placed the hexagon bolt with the hole in it.
Drilled through the bolt into the fixed end, loosened the countersunk screw on the side afterwards, screwed in the grub with the point and let the fixed end find/center position. Angles were still good. No play even with loosely fitted bolts. Then tightened everything firmly.

During the holidays I started on the floor plate, I used a polycarbonate clear plate for this instead of the supplied one. Idea I had was that with a clear floor the torsion bars are visible on multiple places which I think is nice. (For that reason they were painted red).

Regarding the method of securing the engine deck to the hull, I haven't worked on that yet. The idea is though to place brackets on the inside opposite of the long angle brackets on the outside that are part of the kit. These brackets can hold a few strong magnets and some centering/positiong pins.
That way position is always right and the assembly still is quite strong.
But I have to do some drawing on that first to see how it turns out. With the torsion bars now finally in place my first concern is finishing the hull with all electronics in place

[Marco Peter]

...I used a polycarbonate clear plate for this instead of the supplied one. Idea I had was that with a clear floor the torsion bars are visible on multiple places which I think is nice. (For that reason they were painted red)...

Niiiiice

[Tom OBrien]

Roy,

You're going "the extra kilometer" and should have no worries about the suspension once it's built. Kudos to you!

The polycarbonate flooring is a good idea -- it's what I used on my Tiger and works well.

Tom