Sd.Kfz 165 Hummel scratch + HL electronics

[MonsieurTox]

Hey guys,

I've been a huge fan of the Hummel since I saw it for the first when I was a very young kid in the 90's in one of the Tamiya Model Magazine. It was wearing a winter camo. I was blown away.

Since then, I have yet to build one Hummel... More than a decade ago I aquired a Bandai one, not to build it but to use some parts on some Star Wars models I was working on. To be short, the modelmakers who built the filming miniatures for the original movies used hundred of kitparts from Bandai, Tamiya, Revell and so on kits to details quickly them.
I ended up buying about 800 kits (including that Bandai Hummel ) to recreate accurately those filming miniatures.

Well, you would think I'm telling you this story because of that Bandai Hummel, actually no, it's not accurate enough and it's going to be discarded for this project. But to recreate those Star Wars filming miniatures as accurately as possible I started to use photogrammetry (I let you do some google search if you don't know what it is), I went to the exhibits displaying the original miniatures, was taking hundred of pictures then recreate them accurately (with all the flaw of the original) in 3D.

And this is the point. Photogrammetry. This is how I'm going to recreate as accurately as possible the Hummel.
I've been to the Saumur museeum some weeks ago and took several pictures of the displayed Hummel.
Then I processed those pictures in my photogrammetry software, after several hours of manual and computer work I was able to get a good solve of the model that was going to be my starting point to recreate it in my 3D software, using the photogrammetry solve as reference. Of course, since I did not have full access to the original Hummel (interior, back, right side, top), I was not able to get a solve of the whole tank.
However it was a nice starting point, giving me solid reference for the overall shapes, angles of the armored panels, their size relation to the chassis and road wheel etc...

I'm going to use a modified Heng Long Panzer IV chassis (I am waiting 2 HL Panzer IV chassis because I'm building a Panzer IV Beob, which will be a nice companion to the Hummel, using the Trumpeter Beob ausf J upper hull, they seem to take forever to find their way from China haha). I will use several parts that are common to the Panzer IV from the Trumpeter kit (going to mold and cast resin copies of those parts), everything else will be scratchbuilt with styrene, brass, aluminium etc. I will also 3D print some parts with my resin printers.

Here are the mesh of the solve I did in the photogrammetry software. You see it imported into Rhino software in order to use it as reference to build a clean 3D model which will help to create plans I will print to cut the styrene parts.

My 3D model

You can see here the solve overlayed with the 3D model I made

Some various pictures of the 3D model, this is still a WIP but if you see big mistakes, let me know !

hummel4.jpg (97.92 KiB) Viewed 1297 times

hummel7.jpg (94.55 KiB) Viewed 1297 times

hummel8.jpg (85.32 KiB) Viewed 1297 times

[lmcq11]

Hi,

After building a Nashorn and late Hummel myself, I recommend not to base your Hummel on a HL chassis. Considering you need to rework the front and rear of the chassis for length and shapes, reposition the gearbox and the return rollers, put on Panzer III sprocket hubs and sprockets, i recommend you extent your scratch building to the whole chassis as well and create full length parts for it in the proper shape and armor thickness. The HL chassis you ordered could be a source for parts (suspension and mounts, rollers, battery trap) that you cut and transplant on your new smooth chassis. It will be easier for you this way than trying to cut the HL chassis in 3 parts, remove everything that it is in the way (a lot), make and adapt extensions on both end, deal with the warping, create the link to the new upper deck...

I like your drawings, they are looking good. I preferred myself to use the Tamiya 1/35 kit as a source for information for shapes and dimensions. An accurate gun shield is the most complex area to reproduce. I assume you are planning to use the Trumpeter s.F.H 18 15cm Field Howitzer. Room under the hood for electronics is very limited. I prioritized recoil over gun rotation, its more exciting. I was able to give the howitzer 5cm of sliding breech recoil with some elevation. With a detailed interior, it is a very interesting model to own.

Its a big project, have fun.

Louis

[MonsieurTox]

Hi,

After building a Nashorn and late Hummel myself, I recommend not to base your Hummel on a HL chassis. Considering you need to rework the front and rear of the chassis for length and shapes, reposition the gearbox and the return rollers, put on Panzer III sprocket hubs and sprockets, i recommend you extent your scratch building to the whole chassis as well and create full length parts for it in the proper shape and armor thickness. The HL chassis you ordered could be a source for parts (suspension and mounts, rollers, battery trap) that you cut and transplant on your new smooth chassis. It will be easier for you this way than trying to cut the HL chassis in 3 parts, remove everything that it is in the way (a lot), make and adapt extensions on both end, deal with the warping, create the link to the new upper deck...

I like your drawings, they are looking good. I preferred myself to use the Tamiya 1/35 kit as a source for information for shapes and dimensions. An accurate gun shield is the most complex area to reproduce. I assume you are planning to use the Trumpeter s.F.H 18 15cm Field Howitzer. Room under the hood for electronics is very limited. I prioritized recoil over gun rotation, its more exciting. I was able to give the howitzer 5cm of sliding breech recoil with some elevation. With a detailed interior, it is a very interesting model to own.

Its a big project, have fun.

Louis

Hello Louis,

Yes you're right, I will use the tracks, suspensions, gearboxes, idler etc from the chassis, it was cheaper for me than buy them separately, I totaly agree that it will be easier to put all those parts on a whole new chassis made from styrene than trying to modify the HL chassis.
Yes I'm going to use the Trumpeter Field Howitzer kit (should get it tomorrow or on monday), I read your thread with great interest and will follow many of what you did, I'm not sure for the recoil yet, I'd like to do it but Im using the HL electronic and I'm not sure it can be done. I'm going to investigate. Youor model is awesome and I'm not sure mine will be half as good but I will try !

I prefer using the real tanks as reference when I can and fortunatly that's the case with the Hummel, should have less than 1cm error here and there. But The Tamiya kit will be handy for the interior and what I have not be able to photograph on the real one !

I have bought some Panzer III sprocket wheel but I may 3D print some, I did a photo survey of a real Panzer III sprocket and I think I can model one pretty accurate (that fit the HL tracks though...).

Here the photogrammetry of the sprocket :

https://www.youtube.com/watch?v=HEqrIQkSP_E

Need to make a 3D drawing out of it now

[MonsieurTox]

I received my Merit (Trumpeter) s.F.H 18 15cm Field Howitzer today, what an awesome kit ! I may get a second to build it with the carriage.

[Raminator]

Great work with the photogrammetry, it's a good way to get an accurate base to work from with all those complicated shapes. I've briefly looked into it before, it looks like it relies very heavily on decent photos of the subject to work well. I'm looking forward to seeing how you build it from here!

[MonsieurTox]

Great work with the photogrammetry, it's a good way to get an accurate base to work from with all those complicated shapes. I've briefly looked into it before, it looks like it relies very heavily on decent photos of the subject to work well. I'm looking forward to seeing how you build it from here!

Thank you very much Raminator, yes this is a good way to get acurrate shapes when you are able to take good photos. Fortunatly you don't have to use a high end quality camera, today camera of our smartphones work just fine for that matter. Ligthing is very important.

Here's I focused on a link of the B1bis track (Yeah I would like to build one at some point !)
https://youtu.be/agNtmDns8Nk

Here's the manufacturer plate :
https://youtu.be/AQ_1-Z6tu2M

So well, it's awesome when you can use the photogrammetry with a 3D software and a 3D printer (I saw you have some Elegoo printers I have myself 2 Anycubic, the Photon and the Mono X and an Ultimaker).

Well unfortunatly when you don't have access to all the subject you want to photograph you run into some problems.
To be honnest, I totaly forgot to cover the chassis of the hummel, I just focused on the armored panels to get the angle rights, thinking I could find good drawings of the chassis but it is not the case, they all are different and none of them looks accurate when I compare them to the photogrammetry solve (and I trust the photogrammetry solve much more than any drawings ever made, even if they are the original blueprints).
Well I had to do a lot of work, guessing and use of the Tamiya and Dragon kits (which are not 100% correct either) to get something close. The position of the axe of the idler into the hull was my main concern. I may be off by 1mm but well, nothing can be perfect.

[MonsieurTox]

I have corrected the chassis and trying to get it as close as possible. It doesnt show that much, but it has been hours of work.
I received my 1/16 s.F.H 18 15cm Field Howitzer kit and built it so I was able to find it's right position on the chassis.

Note that I quickly modeled the road and idler wheels, the details are not 100% correct, only the size and overall shape are right.


I've started to make the model breackdown in order to sort our the parts I will have to actually cut in styrene. I will be able to make 2D blueprints out of those 3D parts that I will print on paper and use as template to cut my styrene plates.

hummel10.jpg (95.75 KiB) Viewed 1126 times

I still don't know where my 2 HL chassis I ordered are, I know they left China and that's all, tracking hasnt been updated since.

I will start cutting styrene very soon ! I still have some work to do on the chassis.

[lmcq11]

Keep in mind that the placement of the idlers and sprockets depend a lot on the track adjuster, gearbox and sprockets that you will use, and the thickness of the plasticard. It’s difficult to plan too much in advance. Some decisions should be left to later when reality and the situation on the ground become clearer. Some compromises are always required.

Personally, I have found that use of paper templates to help with the design and cutting of parts was impractical. I had to revert back to drawing parts directly on the plastic sheet for more precision, unless the paper templates are laser cut.

[MonsieurTox]

Keep in mind that the placement of the idlers and sprockets depend a lot on the track adjuster, gearbox and sprockets that you will use, and the thickness of the plasticard. It’s difficult to plan too much in advance. Some decisions should be left to later when reality and the situation on the ground become clearer. Some compromises are always required.

Personally, I have found that use of paper templates to help with the design and cutting of parts were impractical. I had to revert back to drawing parts directly on the plastic sheet for more precision, unless you cut the paper templates with a laser.

Yes you're right, I'll do the right adjustment later when I'll have everything in hand. I think I'm going to machine the track adjuster so I'll be able to make to fit if needed !

Well to be honest I was drawing directly on the styrene but I switched to paper template somethings like 15 years ago and never went back.
I tape the printed drawings on the styrene then cut both the printed template and the styrene, I have less than 1/10mm tolerance doing that which would not be the case if I was drawing the lines (thickness of the pen end, measurement). Also to ensure both side are identical, I cut one by hand with a cutter, cut a second one with about 1mm more all around, taping both together and I mill the extra material of the second part. I set my mill so the flat part of the mill bit sit on the edge of the hand cut part. Hard to explain but its a bit the same concept than using a copy shank router bit :
You can this way produce several times the exact same part in the matter of a few minutes

I build scaled models and props for the movie industry and we use that a lot to produce quickly the same parts.

But sometimes I use on styrene blue layout liquid (it's for metal but it works well on plastic) and use my calipers to scribe the blue layout, I get a very thin line this way. I can also draw perfectly parallel lines with less than 1/10 mm tolerance. I've learn that from machinists and it works super well !

[HERMAN BIX]

Shaping up well, this tech'y approach is very interesting.