DAK Pz IV Ausf G Build

[philipat]

With most of the reinforcement completed, it’s time to finish a detail on the front: spare track holders. The flat bar was made using 3-mm brass bar (F-1-3 from specialshapes). It has a slight back curve to it to fit around the tracks and back to the tow shackles. Twist them around and file the ends at an angle to match the angle of the vertical pieces on the tow shackle. There isn’t much flat stuff to fasten it to. So, I drilled a 0.8-mm hole in the tip on each end and in the flat bracket on the tow shackle. Then, I used 0.8-mm hex bolts. Both of these were glued to the tow shackles using JB Weld epoxy. The idea with the 0.8-mm bolts is that they add more surface area for the glue to adhere to. Since there isn’t much to begin with, any little bit more is beneficial. Plus, there’s some added realism to it.

The retention bar across the top is brass rod. The ends were curved slightly inwards and filed flat. The same approach with the 0.8-mm hex bolts is used here. However, I haven’t glued these in. I’ll use a clear epoxy after everything is painted. If I glue it in now, the tracks are locked in place and I have to paint them with the rest of the tank.

Oh, one thing I’m trying is to sand all of the brass before attaching it to the tank. I’m hoping that roughing it up increases the surface area so that the primer and paint adhere better. Some of the paint is already chipping off my brass on my PzIII.

[philipat]

One last thing to do to finish the lower hull’s detailing. I was going to just live with the upside-down handle placement on the idlers. But, seeing KTRob’s awesome work (viewtopic.php?p=140825#p140825) and what he did with his handles, I decided to give it go. I decided to start with his recommendation to try to salvage the handles. And, I kept the great template that he provided in the hip pocket in case I needed it.

Fortunately, I didn’t need it. I used a razor saw to cut off the handle. They’re faint, but my tank had a mold line to follow and get the handle at a uniform thickness. The first cut was a little rough and chewed up a little of the housing. The second cut was dead-on and required very little clean-up.

I used hobby knives and pin files to remove the extra plastic on the idler “barrel”. This rounded it out and gave it the correct shape. It also allowed me to find and salvage the drain pipe that molded in, but very small. Took some carving and filing, but the drain pipes took shape. I drilled them out with a 1.05-mm drill bit.

I decided to glue the crank handles in place. The ends are glued to the barrel and the curve goes where HL molded the drain pipe. Gluing them allowed me to ensure 3 points of contact, which I hope will be secure and survivable.

That should finish the detailing of the lower hull.

[edpanzer]

Looking good Phil I love panzer iv,s hopefully seeing Rob's work in the flesh at the Grantham meet on Sunday

[philipat]

Thanks.

That would be cool to see his work up close and personal.

[KTRob]

Looking good Philipat

I think your a bit tidier than me with those drain tubes

[philipat]

Thanks. You totally get credit for showing me the way. I was going to just ignore it until you broke through that hedge (so to speak).

[philipat]

Got a little distracted and returned to something on the upper hull. After seeing KTRob’s great work on his fender hinges, I decided that I needed to something to correct HL’s rendition.

I started with making the fender springs with .4-mm copper strands from electrical wiring. I wrapped it tightly around a .95-mm brass rod. Note that you need to keep the coils close together because this was an expansion spring rather than a compression spring. The rods holding them to the hull are shortened sewing pins.

Before attaching the springs, I scribed the lines to represent the space between the flaps and the rest of the fender. They don’t go all the way through (flaps are not functional), but I’m hoping that a good pin wash will bring out the scribed lines and make it look like the gap is there. For the rear flaps, I rounded the scribed line on the flap side. I did this because the flap’s hinge was basically the end of the sheet metal rounded into a hinge.

I also cut out the rear hinge points and added the rounded hinge point for the main fender using 2-mm styrene rod. That represents the fender’s portion of the hinge.

I also added some bolt heads to the rear bracket using 1.5-mm hex styrene rod.

The hinges on the front flaps were a bit tougher. I shaved off HL’s molded hinges with a hobby knife and sanded it all flat. Using the same widths of the HL’s hinges (5-mm), I created the hinge flats with .5-mm styrene sheet and cut them into 5x3.5-mm rectangles. I used plastic weld to attached them to each side of the scribed line. Then, I drilled the holes for the rivets (trimmed 1-mm rivets from http://www.scalehardware.com). File the edges of the flats at the scribe line with an angled file to create a seat for the rod that will create the hinge rounds. The rounds were made with 2-mm styrene rod bored out with a 1-mm drill. When I glued them to flats (using plastic weld again), I had a single, large paper clip pushed through both of them. This ensures that they stay aligned. After letting the weld harden overnight, I cut the hinge lines using a razor saw. They’re hard to see; but, again, I’m counting on a pin wash to bring them out. The hinge pin was made using a medium paper clip.

Now the real question...I haven’t glued them in yet (again, not a functional flap). I’m trying to decide between leaving one hinge pin’s handle flipped on the fender while the other lays on the mud flap. Or, do I put them both on the mud flap for the symmetry?

[philipat]

I started assembling the suspension. I’m using the Taigen metal return rollers since they have the rubber tires and are correct for an Ausf G. I tried a few different washers to sit between the supports and the rollers. Standard M3 washers from the hardware store will work, but were a little too wide for my preferences. They were too obvious. The HL washers are the ideal outer diameter (just hitting the diameter of the hub on the wheel), but you have to bore them out. They’re soft; so, they kept deforming on me. I’ll use the Taigen washers, which are somewhere in between and already bored out as M3 washers.

The metal supports look good. But, you can’t use screws with them because the support post they screw into had to be removed to fit the metal supports. So, you have to use the provide pins from Asiatam. Mine came with burring or ridges along the rod and a set of C/E-clips. The clips won’t fit because there’s no groove for them. Also, the head is too wide to fit the outer wheel (Taigen’s metal return rollers are press-fit together). So, I chucked them in a Dremel and used a file to reduce the diameter of the shaft head. Somehow, it came out uneven with one side filed more than the other. I’m not sure how that happened. I’m sure I’ve done this on nail heads a few years ago for a Pinewood Derby car. So, I had to clean it up manually.

I was going to try to create a groove for the clips, but that experience made me question my ability to get an even cut. So, as a last resort, I email Dominique at rctank.de (where I bought them) and asked if I got the wrong parts since I had clips but no grooves. He basically said that there were two versions - one with grooves and no ridging along it and another with no grooves and ridging. The latter stays in place with friction, I suppose. I prefer the pins to ensure nothing gets pulled out...and I made the holes large enough that they slip too easily anyways. He is sending me a set of axles with the grooves. Awesome customer support! Love working with rctank.de and Dominique!

I also have a set of R-clips standing by so that I can play with options.

Oh, for those taking notes: I used a #30 drill for the axle’s hole in the hull side, but that leaves a little bit of wobble. A #31 seems a bit more snug. Might want to go smaller if using the burred version and need a friction fit.

Next step was to install the bogies. I basically used strmnd54's mod to bring the wheels closer together and give compression on the spring. Only thing I haven’t done yet is to solder the back. I’ll do that when I’m convinced everything else is right. Here’s his mod: viewtopic.php?f=38&t=12864 or http://www.rcuniverse.com/forum/rc-tank ... oject.html. I also installed one .5-mm thick M3 washer behind the bogie to give it some stand-off from the hull and facilitate it’s movement.

Note: bogies have full swing without hitting each other.

While test-fitting the suspension parts, it appears that road wheels and return rollers line up well enough. But, they don’t seem to line up with the sprocket. The centerline of the sprocket is approximately 21 mm from the hull. This means that the bogies probably need to be pushed about 2 mm from the full. So, I’ll probably end up using 1.5-mm styrene cut and glued to the hull as a shim with a single .5-mm washer between the hull and the bogie. I’ll probably have to move the return rollers further out by 1-2 mm as well. All of that said, I couldn’t test it for certain because the idler adjusters that I got from Tank Modellbau didn’t work. Their axles were too narrow for the 5-mm bearings on the Taigen idlers.

So, I contacted Tank Modellbau and they offered to update the part with axles that have a 5-mm diameter. They’re in the mail and hopefully gets through customs. But, I’ll have to hold off on finishing the suspension and doing any shims until I get the new parts. Another great vendor...really enjoy working with Tank Modellbau, too.

[edpanzer]

Great build phil love panzer iv,s and this one will be a good one

[philipat]

So, while I’m waiting for my new idler adjusters, I turned my attention to finding a way to secure the upper and lower hulls. Magnets seem to be en vogue. So, I went with that. There are 6-mm square rare earth magnets in each corner and disc magnets in the two remaining posts in the lower hull. (I forget their size, but they fit perfectly.) Large nails in styrene tubing were epoxied in placed in the rear corners and smaller nails were put into the corresponding mid-line posts in the upper hull. I had to use the same disc magnets in the front corners. I tried just using some sheet metal from soup cans, but they didn’t hold. My upper hull has some serious flex and distortion in the upper hull that raises the front corners about 3-6 mm from the lower hull. So, I need enough magnetism to pull them together. That required two magnets on each hull.

I also installed some aluminum tubing for wire runs under the fenders. These protect the headlight and convoy light wiring from the tracks and guide it into the hull. That requires cutting and filing a few notches in the lower hull to allow the conduits to pass through, but very easy overall.