Early Tiger 1 from sPzAbt 503

[cahlfors]

Next thing to develop is the elevation mechanism. There is already a printed prototype in place, that has been there for many years. It is going to break any minute. I could just print a new one, but plastic does not have the desired rigidity. The main gun bounces up and down as the model is driving.

With the recent developments in the FreeCAD CAM (called path) module, it is now possible to do the entire production cycle there. Some tricks are still necessary, but it is way better than using other CAM tools that I have done in the past, as they add to the number of possible errors one could make.

This is the bracket for the elevation motor and screw, together with the generated tool paths:

Over the past week or so, I have been busy trying to cut this part out of wood. There is no end to the possible number of mistakes that are possible to make, leading to interruption of the job and restarting - either with a new wood block or just to run the job again. I wanted to learn and iron out any gcode errors without wasting valuable aluminum. The toolpath generator is new, with unknown reliability, and the operator is a rookie.
But things went quite well:

Over the next few days, I will try to make this part out of aluminum.

[mrTyko]

Exciting, most exciting this part.
Where will the part go in the Tiger turret?

Impressive that you do the test piece in wood and not with your 3d printer, for test fit.

Stay safe and have a neice weekend. "Retirement"
Robert

[cahlfors]

I have printed it to test the fit. It is currently installed in the model.
You can have a look two pages back. I was unable to link the photo again.

The wood model was to test the CAM toolpaths and to learn on something cheap.

[mrTyko]

Aha

Here is two pic's how Stefan has made it in my Tiger.

[cahlfors]

Very solid!

[cahlfors]

CNC milling is fun!

I usually stand there holding a shop vacuum to clear the chips as they are produced.
Things were going well, so I left for dinner. This is what it looked like when I got back:

After cleaning up, this is what it looked like underneath Nice!

The finished part, installed and tested. Most of the slack is now removed, as it was caused by bending of the plastic prototype that has been sitting there for many years. However, there are tolerances in the rest of the mechanism, but the biggest remaining issue now is that the barrel is loose. It will be fastened in a future recoil project and I am happy for now.

[mrTyko]

I'm lying if I say I'm not jealous of you and you CNC.
Looking good the way you did it.
Robert

[cahlfors]

Liam's idlers came today and I just fainted:

I have seen pictures of them before, but seeing them for real and touching them is an immersing experience. Installing them will be the next project.

[mrTyko]

Holy cow they are gorgeous.

Talking of want something.....
Happy for you Christoffer

Robert

[cahlfors]

The idler arms have now been adjusted in the lathe. The old idlers were not tracking correctly and Liam's prototypical idlers have the same basic dimensions, so I wanted to fix the arms. I have removed some material, so that the idlers get shifted inboard by 3mm.

I mentioned somewhere else that I wanted to improve the idler adjustment mechanism while dismantled. I looked at a few different designs to hold the adjustment screw in place and decided on this one, because I happened to have the right bar stock available and then it would be simple.

It looks like this with the crank in place:

I have also been pondering the breakage problem. Everything that can break, if a stone or something gets in the track, is expensive. Or very difficult to replace, like broken screws threaded into the hull. Some argue that replacing a broken track link is simple, which is correct. However, before that link breaks, the entire track gets stretched beyond its tensile point, resulting in permanent deformation and weakening.



This is the idea I came up with:

You can see a bent piece of aluminum rod through the crank and shaft. I am hoping that it gets cut off in an overload situation. Hard to access in the field, unfortunately, but simple and cheap. I have not made any scientific calculations - this is trial and error. If it breaks spontaneously, I will have to find something stronger, like brass. In any event, it has a better chance to save things than the original high tensile steel bolt. I am planning for steel tracks, which means that something else will break when overloaded, like either shafts or the gearbox, so this is the right time to start experimenting.

As I have already experienced the tensioning screw falling into the hull, which loosens the track tension completely, I know the tiger can limp back into the car that way. If the pin breaks, the same thing happens. Not desirable, but I can get it home to service it.

[mrTyko]

Crafty idea with the tension.
Looks realy good.

Robert

[cahlfors]

Time to fit the idlers!

They come with rear detail, which is not only good looking. It makes the hole where dirt can enter the bearing "compartment" much smaller.

Without the tracks on, this area is quite visible... Hm... Attention is drawn to the idler arms... Hm.. I hope the track covers it well!

Finally, the idlers fit on the shaft with the standard screw and no washers underneath to compensate for the tracking error - yay!

Let's install the hubcap!

And put the track on again and tension it!

Now is the moment of truth - can the idler arms be seen with the tracks on?

Yes, if you know what to look for and manage to get your eyes close enough without the nose getting in the way... Those who have reshaped the idler arm have done so for good reason - it is visible, but for now, there are so many other things that are far more visible and that also require attention.

Next project!

[mrTyko]

Whoo First Class Christoffer

Robert

[Hans K]

Otroligt snyggt, fint arbete på dom bitarna.

Hans K

[Erik]

Very nice work!