Early Tiger 1 from sPzAbt 503

[mrTyko]

Nice work Christoffer.
I really like your work with the screw heads.

Robert T

[cahlfors]

Thank you Robert!

That was quite an experiment! The surprises were:
1) That it was indeed possible to reshape the screw heads without breaking them off or something.
2) That it was reasonable in terms of machining time, dulling of the mill bit etc.
3) That the result came out pretty okay looking.
4) That any standard socket did not necessarily fit the new head size, especially 4,27mm. Who would have guessed?
5) As we discussed, it appears that this technique works well for panther screws, too!

But it was fun. Now, I realize that I need twice as many screws as I have, because of a thought erro... eh, I mean, eh. Because of things beyond my control.

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[cahlfors]

Despite thorough cleaning in the ultrasonic cleaner, the surface of the wheels was not ready for clear coating. A second cleaning helped, but did not produce the pristine finish I was after. However, it did help me find more rubber rings that needed reglueing. I am trying to think that I am SO grateful that they came off now and not in the field!

Especially the inner wheels had quite noticeable pitting:

Something had to be done. I decided to put them up in the lathe and give them a good rubbing with steel wool. I actually had to help with a rotary wire brush on the worst spots.

Before:

After (CAUTION: Put your sunglasses on before viewing!):

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[mrTyko]

There was a big difference between before and after.
Robert

[cahlfors]

Clearcoating, finally!

There are a lot of wheels on an early tiger:

And that's just for one side. The other half is sitting on the cart beneath...
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[mrTyko]

Yes there are.

[cahlfors]

It's time to start test assembly of the wheels.

First, when I look at pictures of the real thing, the protruding screw ends look rounded and mine are flat. And ugly...
So, I chucked a (grub) screw up in the motor tool, to see if it could be rounded with a file.
Rounded (left) vs standard (right):

I like the result, so decided it is worth the effort to go through them all. Pretty nerdy, I know... I only wish I could do something about the oversize threads as well, but that's impossible. The nuts are standard M3 and are too rounded in the corners. Considering the success of machining screws, maybe nuts would be possible. I just can't see how... I will leave that for the future. After all, at a later date I can just remove them and replace...

The wheels with the machined screw heads came out like this:

The wheel fasteners have never looked good on my model and I have always wondered what to do about them. Now, I have finally found something that looks reasonably right. I still have to figure out how to bend the brass tabs without scratching everything to disaster.
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[mrTyko]

Wonderful to see fine detail work.

Robert

[cahlfors]

My fantastic auto mechanic let me borrow his sand blasting equipment. It made a breeze with the rust on Liam's idlers :

Like new! Now I need a compressor and sand blasting box of my own.

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[mrTyko]

Boys and their toys

[cahlfors]

With all the wheels now properly clearcoated/sealed, I thought it would now just be a breeze to put the wheels on and then the tracks. But no, there was this one wheel that just would not turn when tightened properly. I had that before, too, and thought it was because a bearing was not properly seated. It turns out that this error is still present (the bearing is supposed to be flush...):

When investigating further, it turns out that the protruding half millimeter is because the bearing seat in the hub is too shallow. Most shortcomings in these kits seem not to matter too much, but this one makes the bearings get squeezed and the wheel not turning properly and so has to be addressed.

I just bought a collection of mills and now, the problem of organizing them in a "tool library" in the CAD/CAM software (FreeCAD), has become urgent. So, first, study hat on and getting organized, then deepening the bearing well. If the part were well made, just a quick whiff in the lathe would do the trick, but the bearing well is very much off center, so has to be milled deper with its off-center hole as reference. Pretty simple per se, still, but with the tool chaos needing addressed, it will be a while before the tracks are back on...

Gosh!
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[cahlfors]

Progress already!

Who would have thought! I managed to find an addon for FreeCAD named Better Tool Library. It is very intuitive and I could just start moving the already defined tools into its structure. Measuring and entering the rest of the tools is a bigger activity, but can be done whenever.

It's also amazing what CNC can do. I would never have been able to do this manually. Creating a tool path for deepening the bearing well was a breeze and went very well, indeed:

The end result:

Fortunately, the other side had no binding wheels and I can now move on with mounting the sprockets and track. Yay!
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[mrTyko]

Good work

[cahlfors]

Mounting sprockets and track went well:

The inside has also been repopulated and tidied up a bit:

The battery cells got boxes to protect them better. I discovered on the Jagdtiger that the aluminum casings are connected to + and thus very much live.


The next thing I wanted to do was to address the gun movement. It has a wobbly fit and it has annoyed me for a long time. I know the primary reason is the hinges and so I drilled out the mantlet backpiece and made brass inserts with better precision:

The backpiece reinstalled in the turret. The fit is now a little tight, but with a drop of oil it moves okay and with zero play.

I know there is more to do with regards to milling, but that will have to be for next season or so.

Next was the gun barrel itself. I have had it sit loose in the sleeve, which added to the bounce when driving. In order to fix it, a threaded tube needed to be added at the rear of the gun barrel. I didn't have any such big threading dies and besides, it did not have an "M" standard pitch. I have heard since woodworking class in eighth grade that "you do that in the lathe" and always wondered how that was supposed to work, picturing myself in front of a wood lathe and a chisel in my hand. I have now read a book on how it's done and decided to give it a try. Very complicated, but worked almost on the first try (I had a lever in the wrong position on the very first cut, but that could be fixed):

And lo and behold - it fit the barrel on the first try!

Gun with tube installed in the turret:

The idea is to clamp the tube to linear bearings in the future and have a working recoil. For this season, it will be non-moving. In all, half the gun bounce is now gone. The rest of the play is in the elevation mechanism itself. Let's see if that can be addressed as well...
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[mrTyko]

Progress Great progress my friend.
Thank you for sharing your work tips.

Robert