Sd.Kfz. 7 half-track, post-war

[Jakko]

Over on the TWENOT forum, Arjan Wiskerke posted this photo of my subject, that I had never seen before:



It’s earlier than the ones I posted above, because the outer roadwheels are still on and the ammunition rack inside the load bed is there too, though at a rather strange angle The front rims have been taken off, but I guess they were put back on soon after the picture was taken in order to be able to tow the vehicle, perhaps? And it shows the number plate, which is a real plus — means I won’t have to make something up

 

[Jakko]

With thanks to a (luckily mild) bout of COVID, I haven’t done any work on pretty much anything for the past week or so. Now I’m feeling mostly well again, I decided to continue on this model. To get it to sit right, I needed to first get the front rims to the correct thickness, because the Dragon parts have a raised area that the tyre glues to, and also build two short lengths of track to go under the roadwheels while I work out the suspension angles.



Top left is an unmodified rim, top right is one that has been turned down, with thanks to my father and his lathe. It’s too thick, sure, but getting it even close to scale thickness will probably shatter the rim completely, and at least it now it looks believable.

The tracks are provided as separate links of Dragon’s “Magic Track”, which means you don’t need to do any cleanup. Supposedly. In fact, of you look at the photo, you can see there is an ejector pin marking on each of the two sides of the link, so lots of fun to be had scraping all those down (I tried filing first, but that fills the six little holes with plastic dust, removal of which alone seems to be more work than scraping down the link is.)

Running gear parts:



The different sections with track parts are (from left) links not cleaned up yet, track pads, cleaned-up links and rejected links. I managed about fifteen links before my fingers hurt enough that I decided to continue some next time and instead, went to work on the load bed:



I had actually built this last weekend before I got ill, and already noticed at the time that the supports are wrong for the artillery tractor version of the Sd.Kfz. 7. On looking through the Panzer Tracts and Nuts & Bolts books for this vehicle, I noticed that this is because these supports are for the Sd.Kfz. 7/1 and /2, that carried an anti-aircraft gun — the artillery tractor had more lightweight bracing, but I haven’t found a good view of how and where it fits yet.

The problem is that Dragon took a shortcut and included the load floor for an anti-aircraft vehicle that they already had, rather than making an accurate one for the tractor. This vehicle shouldn’t have the transverse ribs you can see in the picture, for example, and the hinges along the edges are of a heavier type that was used with the AA vehicles (because the sides needed to support people standing on them when folded out horizontally) but not the artillery tractor.

 

[Jakko]

And that’s the floor modified:



I removed the supports again, cut the ribs away with a chisel-shaped blade and cut and filed the hinges off the sides. The edges will probably need to be thinned down still, as I think they were steel profile on the real thing, so nowhere near as thick as these.

 

[scottie3158]

Jakko, the wheel looks a lot better.

 

[Jim R]

Hi Jakko
Very useful extra photo. Wheel looks fine. I assume the one on the other side is the same? The load bed modification looks straightforward.
Glad your bout of Covid was mild. Seems that for some it is but for some others it's much worse.
Jim

 

[Jakko]

the wheel looks a lot better.

Definitely, it just looked wrong with that raised centre section. Not a problem if you fit the tyre, of course, but it’s rather obvious for what I have in mind.

Very useful extra photo.

I’m kind of hoping he digs up some more

Wheel looks fine. I assume the one on the other side is the same?

Of course The kit includes four, because the number needed is three (two front wheels and a spare), and they’re on a sprue that’s in the kit twice, so I could photograph one of the two corrected ones, and one original. It handily provided a margin of safety in case something went wrong with turning them down too

The load bed modification looks straightforward.

It is, but made more complicated by me having already added the longitudinal ribs and not wanting to remove them

Glad your bout of Covid was mild. Seems that for some it is but for some others it's much worse.

I only had it fairly severely for about a day and a half in the middle of the week, but still didn’t feel like doing much of anything in the days since. Today, I’m much better, though I still have symptoms. A few more days and that’ll be over too — I hope …

 

[Jakko]

Let me sing the praises of some tools I don’t use much, but which I wouldn’t want to do without To adapt the rear suspension to the nose-dive attitude, I needed to cut free the arms from the mounting plates that they are moulded integrally with. That’s a tricky job because it needs sawing in tight spaces on a part that’s perhaps 4 or 5 cm long, at a quick guess, and basically needs to be cut in half at that. To hold something like that, a fully adjustable, modeller’s vice is a very good tool to own:



Because of the swivelling upper part, you can position it as you want for most convenient sawing, drilling, filing, etc. unlike with a standard, fixed vice, where you have to adapt to its position. It’s not that cheap, but if you convert or scratchbuild things, you’ll probably soon find yourself glad you bought one instead of another kit for the stash

The other is one I’ve mentioned before:



Saw blades for a knife handle, made from the same steel as regular modelling knife blades so they don’t twist or buckle. They’re thicker than a typical modelling saw, but their strength means they have very low height — which I needed here to get the saw into where the cut had to be made. A regular saw would not be able to get past the axle bearing, or at least, not without sawing at an angle instead of right along the mounting plate.

After a little work sawing, and filing the backs of the mounting plates flat, I ended up with:



(And then I did the other one too, of course ) To make up the thickness of material I had sawed away, I filed the rounded bits off the suspension arms as well and replaced them by punched plastic card discs, 0.5 mm thick and 4 mm diameter. The mounting plates, I glued to the chassis with a 5 by 7 mm rectangle of 0.75 mm card between them to make the plate I had removed between the suspension arms:



I then went and dry-fitted the subframe that goes below the suspension mountings, and found it wouldn’t fit correctly … Turns out I had the mountings slightly too far to the rear, due to not having any locating pins anymore, I suppose. Easiest solution: slice them off again with a knife while the glue was still wet, then stick them to the subframe instead:



That way they’re guaranteed to line up with it, at least

 

[Jakko]

Or, of course, you pay proper attention:



I had glued the mountings to the wrong arms of the subframe, because I had been dry-fitting that frame the wrong way round

That snag fixed, I could finally try to line up the suspension. My idea had been that I could leave the rear arm in its default position and compress the front two. Trying to get everything lined up that way, though, I found out that when the front arm is compressed all the way (up against the chassis), the rear wheels are off the ground:



The cardboard is about the same thickness as the track. The original plan was to set the vehicle up on two lengths of track, but they roll under the model’s weight and it slides off, so I found some cardboard of the right thickness (within a few tenths of a millimetre) and cut a bit of that.

This with everything (other than the rear arms) still loose, the front arms held in place with Blu-Tack and the wheels and axles just pressed on/in. You can just see the rear wheels are off the ground, but it’s worse on the other side — which in itself means there is something wrong with how I have it lined up. The fundamental problem is that half the parts want to fall apart while the other half have too much friction to move easily. I think I may have to drill holes to insert actual axles for the suspension arms, so they will be kept properly in place and simply fall to their correct alignment, but I’m not really looking forward to a job like that.

Alternatively, I guess I can stick the front suspension arms in place, then line up everything else separately once they’re firmly set.

 

[adt70hk]

Coming on nicely Jakko despite your problems. Hope you're able to sort it out ok.

ATB.

Andrew

 

[Jim R]

Hi Jakko
Who would have thought that what seemed like a relatively straightforward bit of alteration would throw up so many issues. I'm sure you'll sort it.
Those saws are good. I've not seen such a useful vice for modelling before.
Jim

 

[Jakko]

Coming on nicely Jakko despite your problems. Hope you're able to sort it out ok.

Oh, I will — it’s just that I’m getting mildly frustrated by having to stop and think some more about what I thought I had figured out and just needed to do. But this is par for the course for models I build

Who would have thought that what seemed like a relatively straightforward bit of alteration would throw up so many issues. I'm sure you'll sort it.

To be honest: I’m building a semi-wreck, so it’s bound to be slightly complicated However, trying to find out how the supports for the load bed should be, I decided to look at the instructions for the Trumpeter kit of this vehicle, and I discovered I would have been better off buying that one instead. It has the correct load bed supports, narrower spare wheel carrier, bolts on the underside that are missing on Dragon’s kit, and more … The only thing Dragon appears to have going for it, is tracks that are easier to clean up and assemble. But I’ll stick with what I have, I guess.

I've not seen such a useful vice for modelling before.

I came across it at a model show a decade ago or so, and it looked so useful that I bought it there and then. I’ve never regretted it. It may or may not be obvious in the photo, but it clamps onto the workbench: there is a screw handle underneath so it can be tightened to almost any thickness of work surface. The handle you can see sticking out is the lock for the position: release that and you can tilt the upper part as needed.

 

[Jakko]

We’re getting somewhere now … I glued the front suspension arms in their maximum upward position, against the chassis, and removed the rear suspension arms I had glued on a few days ago, then sawed off their side mounting plates much as before. Next, I added the front two roadwheels on each side again and lined everything up, which proved impossible because the left front wheel (the normal wheel) kept coming off the ground by about a millimetre. In the end I decided this was because the front axle is not on quite straight, so I bent it and its spring down on the left until all six wheels (two front and four road) were touching the ground:



You may notice I replaced the cardboard by a piece of hardboard, because it is more even in thickness. With the wheels lined up, I touched liquid cement to the joint between the axle piece and the suspension arm, then let it set for a while. Next, I added the rear arms again, but now deflected downward, and repeated the procedure:



I’ll add the middle ones only when the glue had dried, to avoid disturbing these. Hopefully, I can just stick them on and line them up using a ruler, but I’m not expecting it to be that easy

 

[Jim R]

Good job Jakko. It looks to have worked well. Maybe fit the other wheels using the same set up, same bit of hardboard.
Jim

 

[scottie3158]

Jakko,
That has worked out well.

 

[Jakko]

Maybe fit the other wheels using the same set up, same bit of hardboard.

That’s what I ended up doing, and it worked perfectly.

That has worked out well.

More easily than expected, really. When I couldn’t get the left front wheel on the ground I was scratching my head quite a bit. Walked away, came back later and decided it needed some force applied rather than cleverness

 

[MAK2020]

'' So, when I came across this picture while doing research for my book that was published last year ...''

Which book?

 

[Jakko]

Which book?

This one

More information here.

Back to this model: here is the chassis with all the axles on it, plus some more details:



After aligning all the axles, and letting the glue dry, I added the leaf springs. Those at the back are easy enough: they would need to bow out more so they will reach the rear suspension arms, but because this will be hidden behind the wheels, I didn’t bother trying to fit them like that. The ones at the front needed to be bent flatter, because of the way the suspension arms compress them. This was tricky, because the thick parts are hard to bend; I managed with my fingers plus pliers to bend them far enough that they fit as they (more or less) should.

About ten minutes after glueing them on, I noticed that the axles were no longer in line Worse on the left than on the right, but when I put the wheels on, the whole vehicle rocked on one wheel in the centre pair on each side …

What happened was, of course, that the springs had bent back slightly, pushing the middle arm down (the front one was glued down at more points, and for about 24 hours longer). I had a fun time trying to bend the spring back up, and the arm under it, without breaking anything. It succeeded in the end, but I hope I won’t have to do that again …

By the way, the reason some of the axles are shorter, is because for the middle row of wheels, some wheels don’t seem to want to go onto the axles all the way. Easier to cut about a millimetre and a half off their axles, than to try and drill them out so they fit as they should.

 

[Jim R]

... decided it needed some force applied rather than cleverness.

Ah right up your street then

Only joking. Glad it's done.
Jim

 

[The Smythe Meister]

Only caught this on my phone a short while ago Jakko!
Gotta say,one of my favourite vehicles,a great "real life scenario" to capture with some cracking information freely given....
I'M HOOKED!!
Superb looking progress so far,(not to mention excellent,clear photos), obviously,I'll be checking in all the way from here on in
Great stuff!!
Andy

 

[Jakko]

Ah right up your street then

Yeah, brute force is what I’m best at, that’s why I build plastic models

Gotta say,one of my favourite vehicles,a great "real life scenario" to capture with some cracking information freely given....
I'M HOOKED!!

Great you like it