My Jagdtiger by Per Sonnervik

[Paul Morris]

Hello Per.

Outstanding as expected, lots of things to think about if only there was more time.
Kind regards Paul.

[Robert E Morey]

Per,
Wow, fabulous machine work and design. Those swing arms are a work of art. Thanks for posting! This will be a fantastic model.
Best regards,
Bob

[Per Sonnervik]

Paul and Bob, thank you for your kind comments.

My next work was the Jagdtiger hull and there are two ways to do this; convert an Armortek Tiger II model as Paul Morris has done or start from scratch, which I decided to do.

My idea was to make drawings on CAD and then have them waterjet cut (due to the plate thickness) - I thought that would make things easier. I had never used CAD before but I had a friend who knew how to do it and we first made the Tiger II hull and then the Jagdtiger.

I decided to change some details on the CAD drawings compared to the real plates, see below;




Notes A and B are simply not practical to follow from the original, changes on A refer to the top of the lower side armour;




and B is where bottom plates meet;




Notes C and D had to be made as this is where the lower side interacts with other plates;







A view of the other side show some more details, this an early drawing with not all details showing;




On A I picked an easy solution which I later changed, B is not correct (which I changed), C is too high up (which I missed) and parts D and E I later decided to have cast.


One more deviation from the original was the rear plate of the superstructure;





After the hull had been drawn it was a matter of reducing the plates to 1/6 scale and change the files to dxf files (which are used by the water/laser cut companies) and here is where things went wrong...

More later, Per

[Per Sonnervik]

After I got the plates I soon realized that something had gone wrong. Material was missing on the plates and the odd thing was that it wasn´t in the same places on some of the plates i.e. the front plates. It turned out somehting had gone wrong when converting the CAD files to the dxf files but I had no program to view these files before sending them to the cutting company and my CAD friend failed to notice.

Talk about disapointment - I thought it´d be plain sailing from now on after all the work on the CAD drawings. I was very close to give up as I feared it would be very hard and time consuming to add (thin in some places) material and then machine these areas.

In the end I decided to give it a go and see how things turned out. Besides from adding material I also had to machine the thickness on almost all the plates to get the correct scale thickness. As my milling machine has a fixed head I bought a 3-way vice and a digital protractor and without these I wouldn´t have been able to machine the plates.

I didn´t take that many photos as I had my hands full but two of the first was these;



I´ve machined parts of the front plate and the lower front to be able to put them in place. On the front I´ve written comments on missing material. The rear looked like this;





Next step was to work on bottom plates, the lower sides and the square bar (that holds the suspension bearings) to be able to screw them together;




In the photo below I´ve done a lot work and now started trying to work out where to fix the upper side walls in the right position, held in place with plastic pieces;



For those with sharp eyes you can see I´ve written -12 on the side plates which means that it´s missing 12 mm. I also had to mark out where the mudguard brackets are to be (B) to avoid putting a screw (A) in this position. I´ve added extra material to the upper and the side of the front plate.


In the next photo I´ve fixed the upper side plates and is trying out the superstructure front and rear plates;




and also worked on superstructure rear plate;



I´ve added a thin strip on top of the rear plate and noted that I had to add a 5 mm piece to the rear of the roof plate. B is the square bar for the supension bearings.


A heavy thing to work on was the superstructure front and I decided to rework the lower part to closer represent the original (which is cast as one piece);



A thick piece is added on the lower part and I´ve machined and filed the sides. I had to add a piece to the top as well and then remove parts of it;




I worked on the 12 mm added material on the lower edge on the upper sideplates plus added and machined other parts;








To add material I either glued and screwed it or nailed and glued it, like this;






Below is a combination of both using nails and screws to fix the extra material;




and this is what it the same part of the front plate looks like from behind;




The next photo show how I worked on the top of the upper side plates and that meant I had managed to pull it off and I am pleased I didn´t give up. Hopefully the added material won´t show when it comes to painting but at least you´ll know if they will.






Cheers Per

[Paul Morris]

Hello Per.

Looking great a testament to all your hard work, well done my friend.
Cheers Paul.

[simon_manning]

that is a story of perserverance and stamina, best to have a rest for a while, make some small parts, superb regards simon.

[Tim Bowman]

Looking good Per

Is it as heavy as it looks?

kind regards
Tim

[Derek Attree]

Hi Per
That is nice my friend.

Regards

Derek

[Per Sonnervik]

Paul, Simon, Tim (it´s heavy and front heavy too) and Derek, many thanks for your kind words.

To get some variation I turned my attention to the engine deck. I had drawn the round and square outlets to be waterjet cut but decided to have them cast in alu instead. I provided Stefan Konitzer, a Swedish Armortek builder, with all the dimensions and he had them 3 D printed - thanks Stefan. I was a bit worried as these parts are not that easy to cast but I found a foundry with a guy who was willing to help me and the result looked like this;






I knew the scale cast no´s on the round outlet part wouldn´t come out that clear but we had them there as Stefan settled for plastic pieces. I removed leftovers from the casting process including A and had made a jig to be able to work on the side that´s towards the engine deck, see below;





After I had all the engine deck plates machined to the right thickness and replaced the scale part no. with a white metal plate (see arrows) I had a chance to try out the parts;



and with the square intakes (still not 100 % cleaned up) loosely placed in position it began to look the part;




I mounted all the parts on an alu plate and this is how it turned out. The small rectangular pieces close to the rear armour have not been fixed in this photo;



I tried it on my Tiger II hull and it fitted there too, so I must have done something right;



It´s far from finished but the major parts are done (except the engine hatch) and I could return to the hull.

Cheers Per

[Kent Wiik]

Hi Per,

Very, very impressing
I'm out of words.
Your skills an knowledge is mindblowing.
Thanks for posting this inspiring build(s).

Kind regards
Kent

[Robert E Morey]

Per,
Great job on this - and for not giving up! It looks massive. The cast Aluminum parts came out very nice. Did you figure out what went wrong on the cutting? I'm scratching my head on that one. Sometimes I forget if parts are inches or metric and this leads to scaling errors. But you shouldn't have that problem (inch vs mm)in the UK!

Looking great - keep the momentum going.
Bob

[Per Sonnervik]

Kent, I do appreciate your positive comments. You´ve set the standard with very informative posts on this forum. Unfortunately it wasn´t possible to go into all the measurements and details here - it would´ve taken years, perhaps when I get to all the smaller details.

Robert, I wanted to know what went wrong as I´m planning to do a Tiger I (late) and a Panther G (if I live that long) too. It´s nothing to do with the metric system but instead when converting the CAD file to the dxf file. What you do is that you make a "Flat pattern" in the program, and depending on which side of a plate you point at when doing the "flat pattern" it turns out differently (being an amateur when I started I didn´t know this) and to illustrate this I use a cross section of a Tiger II/Jagdtiger front plate;



If you do a "flat pattern" and point at side A, the program finds edges A1 and A2 and that will mean you will "loose" material at area C, but not at D which is exactly what happened with my Tiger II front;




On this plate I had to add material A but nothing at arrows of B.

If you use side B when doing the "flat pattern" you´ll have a plate with edges B1 and B2
and this corresponds with my Jagdtiger front plate as I had to add material at area D.

So, when doing a flat pattern you´ll have to have this in mind and correct the drawn CAD plates (by adding in the program) when this problem occurs. It´s not a problem on straight plates but only on angled ones.

I hope it´s a bit clearer.

Cheers, Per

[peter karlsson]

HI!!

ABSOLUTLY AMAZING PER!!!!!

looking forward to see this build!!
you and kent have realy master eyes for details!!!

rock on Per!!



reagrds peppe.

[Robert E Morey]

Per,
Thanks for the explanation. Totally makes since what happened with the cutting now. Yes plates with angled edge one must make sure to cut to "maximum material condition" otherwise it can end up undersized. One must also account for the tapered kerf of the waterjet on very thick plates. Glad you were able to recover your parts and not have to remake them!
Best regards,
Bob

[Per Sonnervik]

My next work concentrated on the bottom plates with all the covers but also the bottom edges of the lower side plates and others.

The photo below shows that the different bottom covers all are similar except A, B, C and the escape hatch, different in size only. I´ve also added square reinforcement plates.



the inside looks like this;



Covers A (bottom valves) looks like this close up;



are made up of the following parts;




The cover B (fuel pump cover) the bolt holes has special look which I made in two stages;



Cover C (water drain valve);



The standard covers were all made the same way; holes were drilled and with a special drill the bolt holes were recessed and then the sides were beveled;



and all the covers (except valves A) have a rubber gasket made from 0,5 mm thick rubber;




The escape hatch was made and I haven´t decided yet if I´ll do the interior too, will see. The very first hatches on the Tiger II had a bevel all around the hatch but this was the standard type;




and in the correct position;



I finish with a photo showing some of the work done to the lower edges and the bottom plates;




Cheers Per