Panzerhaubitze 2000, 1/24 scale, Scratchbuild

[Bandsaw Steve]

2 minutes ago, Marklo said:

a modern track is going to be quite a challenge.

 

Only if I try to do it well! 🤪

 

I think a good thick rubber band should do. 😉

[Bandsaw Steve]

2 hours ago, Marklo said:

How are you going to do the tracks.? 

 

Resin cast from a master?

 

At this stage that’s plan ‘A’

 

If I get to - let’s say - plan ‘D’ and haven’t got a result then I’ll concede defeat and try 3D printing.

[Marklo]

Hmm much as I love 3D printing in the real world, I still feel it’s sort of cheating in a modelling context. I mean in a few years you’ll just be able to print out the whole model, camo markings and all ( although you can probably already do this on high end machines) Where’s the fun in that. To summarise wonderful for industry awful for hobbyists. Especially ones who are still hacking things out of blocks of wood.
 

Puts soap box away....

Edited April 13, 2020 by Marklo

[Bandsaw Steve]

I try to only use 3D printing when I’m out of practical alternatives.

 

As a rule I don’t enjoy using computers, I often find them strange and frustrating things, so have so far avoided using them in my hobby unless really pressed.

[Bandsaw Steve]

Turret. Part 1

 

Right... no fancy wordsmithing here - this thing needs a turret so let's get on with it.

 

You probably know this part of the story by now. Cut out the relevant shape and stick it on to some poor unsuspecting bit of MDF.

 

Like this for example.

 

Hack into the thing with a bandsaw leaving a fine selvedge around the outside.

 

Sand away the surplus.

 

Check that the shape looks about right.

 

Cut out another bit of MDF that will form the backbone of the thing.

 

Take a Stanley knife and cut a slot along the long-axis of the first shape.

 

Work a chisel into that slot and slowly, carefully split the MDF into...

 

Two identical bits. Tricky huh!

 

Now use some precision instruments to mark out some rebates in the dead centre of each template. In this build I'm trying to pay more attention to precise and accurate measurement than I have in previous projects. Being careful now saves time later.  In any case precise and accurate measurement of distance and direction is the key to success with artillery.

 

Cut out the rebates and check for a snap fit. Here it's looking pretty good.

 

Repeat the entire process with these two bits that stick out the front. The gun will be mounted between these two plates...

 

and will elevate by pivoting on this axis.

 

Here is the basic skeleton of the turret sitting loosely on the hull.

 

So far so good.  No major disasters yet.

 

YET... 🤔

 

Bandsaw Steve

[JohnWS]

Coming along nicely!

 

I never would have thought of splitting a part to make an identical twin.  

 

John

[Bandsaw Steve]

21 minutes ago, JohnWS said:

 

I never would have thought of splitting a part to make an identical twin.  

 

I wouldn’t have either. My dad dreamed that one up. Smart huh! 👍

[ArnoldAmbrose]

On 4/13/2020 at 10:35 PM, Bandsaw Steve said:

computers, I often find them strange and frustrating things

Gidday Steve, They make great boat moorings. Get a length of chain or rope, attach a float to one end, the computer(s) to the other, throw the computer(s) into the river and 'presto', instant boat mooring.

I'll concede that they do have their uses when consulting modeling forums however.

 

I seem to remember you using your dad's idea of splitting MDF on a recent train build? I would have clamped two thin pieces together instead. I should try your (dad's) idea sometime.

Regards, Jeff.

[Bandsaw Steve]

Either way is good - splitting probably gives a more precise duplication of outline but you end up with one face that’s’furry’ on each part and the two parts won’t be exactly the same thickness. But another advantage is you can split again to set the thickness if you need to.

[JohnWS]

21 minutes ago, Bandsaw Steve said:

I wouldn’t have either. My dad dreamed that one up. Smart huh! 👍

Yup!  👍

 

John

[Ray S]

Hello Mr Bandsaw,

 

This is progressing well. You have come up with some very interesting ideas (even if one was nicked from your pa!). The solid hull does at least mean you do not have to build an interior...

 

It is a long time since I have been in the AFV Section here, so you may take credit for that.

 

Look forward to seeing more.

 

All the best,

 

Ray

[Vaastav]

Great work. Nice scratchwork. I can only imagine the amount of skill required.

Kudos.

[Bandsaw Steve]

24 minutes ago, Vaastav said:

 I can only imagine the amount of skill required.

 

Thanks! But I suspect it’s not as difficult as often assumed. Part of the reason I chose the PZH 2000 is that most of its fundamental shapes are fairly straightforward so that helps a lot. I think the biggest challenges will be tracks and wheels. We’ll see how they go. 😉

[Bandsaw Steve]

Moving Parts...

 

I well remember from when I was but a lad, my dad telling me 'When building a model never put anything on it that moves - people will just play with whatever moves and break it'.

 

Almost without exception for the rest of my life I have followed that advice and have stuck to strictly static models. This one however will be an exception. This is a self propelled howitzer with a gun mounted in a fully traversable turret, so it is really a necessity that the gun should at least be able to be posed in different combinations of traverse and elevation. Despite various people suggesting that this should be motorised and controlled with a mobile phone 'app' that is not going to happen. The traversing and elevation will be done by hand.

 

Here's where we last left things, let's see what happens from here.

 

Find a bit of plywood and mark out / cut out an appropriate size circle. Use this 'centre finder' thingamigigger to find the true centre.

 

See, there goes the dead centre, right there! Clever huh!

 

Drill a hole, line it with a brass tube and bung a brass axle in. Now there's a pivot and a nice circular base for the turret to rotate upon.

 

Do the same sort of thing on the turret. I.E. drill a hole, fit a brass sleeve and....

 

See that it fits onto the upright pivot axle thing...

 

Now check that it turns O.K.- Which it does!

 

Now add a base of thin plywood to the turret.

 

And use a paper cut-out pattern to start working on the breach of the gun itself.

 

Use a bandsaw to cut it to shape and a bench sander to make fine adjustments....

 

Like these tapered ends for example.

 

There are little sort of 'faceted' edges towards the front of the breech / recoil assembly. These can be created with a sharp chisel.

 

Now drill a hole right at the centre of the rear of the breach assembly and score some cross-hatching in preparation for using some...

 

Araldite 'Super Strength' two part Epoxy Adhesive. I've never used 'Super Strength' Araldite before, but this next joint must never ever let go because it will be inside the turret and will need to hold on a part that in future will be exposed to some stress when the barrel is elevated.

 

And that part is this washer...  It's going to get glued into place.

Gluing metal to wood can be a bit fraught so let's hope that the 'Super-strength Araldite' is up to the job. It should be, I have great faith in two-part epoxy.

 

Clamp the part in the vice for a few hours to give the glue the best possible chance, then take the breach out and assemble the model as shown...

 

The elevation 'mechanism' at this point is very simple. The breach assembly just pivots around a brass trunnion, it works nicely enough, but there is a small remaining problem and we will address that in the next post. Feel free to guess what the issue is if you like.

 

And with a basic representation of the gun  
barrel fitted, here’s what it looks like so far.

 

I think it looks OK and so too does my wife who said  my 'little boat is looking very good' 

 

OK - that's most of the twisty turny up and down stuff sorted out. Like I say - there's a bit more to come in the next post. 

 

Still no major dramas with this model. I'm getting nervous...

 

Bandsaw Steve.

 

 

 

 

[brianthemodeller]

7 hours ago, Bandsaw Steve said:

Despite various people suggesting that this should be motorised and controlled with a mobile phone 'app' that is not going to happen.

 

Would you be able to use the app to control the firing mechanism and smoke discharger as well?

 

 

 

 

 

 

I know you said it wasn't going to happen but I reckon you want to really...

[Murdo]

45 minutes ago, brianthemodeller said:

 

I know you said it wasn't going to happen but I reckon you want to really...

 

Yup, I reckon he does too.

 

[Bandsaw Steve]

3 hours ago, brianthemodeller said:

 

I know you said it wasn't going to happen but I reckon you want to really...

Perhaps I should tell you what I really do want to happen! 🤬

[hendie]

52 minutes ago, Bandsaw Steve said:

Perhaps I shouldI tell you what I really do want to happen! 🤬

 

oh dear, there goes his Turret syndrome again

 

 

 

nice boat Steve

 

 

[ArnoldAmbrose]

12 hours ago, Bandsaw Steve said:

 'When building a model never put anything on it that moves - people will just play with whatever moves and break it'.

Gidday Steve, on the other hand, if it gets bumped there is a bit of give, less likely to break I find. And as a deterrent to stop people playing with it, have a set of bolt cutters in view, nearby. You know, finger size.

12 hours ago, Bandsaw Steve said:

The breach assembly just pivots around a brass trunnion, it works nicely enough, but there is a small remaining problem and we will address that in the next post. Feel free to guess what the issue is if you like.

Balance? Without a counterweight at the rear of the breech the gun will always want to droop. Alternatively, a bit of friction on the trunnion might suffice.

 

On a serious matter of definition, what is the difference between a self-propelled gun with a fully revolving turret, and a tank? The turret being open on the SP gun, enclosed on the tank? Just interested.

 

Looking forward to seeing more progress on your remote controlled, motorized, smoke discharging, live firing boat. With lights. Regards, Jeff.

 

 

[Bandsaw Steve]

5 hours ago, ArnoldAmbrose said:

And as a deterrent to stop people playing with it, have a set of bolt cutters in view, nearby. You know, finger size.

 

Balance? Without a counterweight at the rear of the breech the gun will always want to droop. Alternatively, a bit of friction on the trunnion might suffice.

 

On a serious matter of definition, what is the difference between a self-propelled gun with a fully revolving turret, and a tank? The turret being open on the SP gun, enclosed on the tank? Just interested.

 

Yes. Bolt-cutters would suffice but I prefer a Bandsaw.

 

Good guess on the droopy barrel. Quite right. This might be something you may wish to discuss with your doctor.

 

OK - tank vs SPG...

 

I’m no expert (and many here are) but here’s my understanding:

 

Tank: designed and used to capture and occupy territory and typically used in direct close contact with the enemy. Hence; highly mobile, heavily armoured & armed with a direct fire gun. Observes and destroys its own targets. 

 

SPG: designed and used for fire support (typically indirect fire). Typically used at some distance from the enemy. Hence; compared with a tank, slightly less mobile, significantly less heavily armoured but heavily armed with a very long-range gun controlled by distant forward observers. Typically used in concerted fire missions involving many guns under central battery or regimental control.

 

Now let’s see what the knowledgeable folk say...😀

[ArnoldAmbrose]

Gidday again, I thought your choice of bandsaw was as a modeling tool, not a deterrent to those with itchy fingers.

 

Regarding the different definitions, that makes sense, much of the definition being as to it's deployment and hence mobility, rather than simply does it have an enclosed turret.

 

And my doctor is insisting on social distancing, 1.5m spacing. Ooooh, let's not go there. 😁 Regards and stay safe, Jeff.

 

 

[Bandsaw Steve]

Steady... Steady...

 

That's what they say in the Army sometimes - 'Steady lads... Steady...'  I know 'cause I've seen the fillums...

 

As @ArnoldAmbrose has quite rightly pointed out, without a counterweight or some kind of friction device, our very long 52 calibre gun barrel is not going to sit still at any given elevation. It's currently not steady and will droop to a very saggy depressing looking position at a moment’s notice.  That's no good. What I want is a gun that, just like the real thing,  can elevate to +65 degrees depress to -2.5 degrees and be poisitoned at any angle in between. Just as importantly, when the gun is set to any position I want it to stay there. Nice and steady...

 

I'm guessing that there are various ways to do this but I have chosen to use magnetic door catches.

 

Each door-catch is a solid magnetic block with two little square,  stainless-steel, metal plates stuck on the sides. Somehow - and I really don't know how - the plates on the side seem to make the magnetic effect of the core magnet much stronger. I'll have to google that one day and work out how. In any case I figured that if I arranged four of these rather strong magnets around the stainless steel washer that I had previously fitted at the breech of the gun, then the magnets would grip the washer and hold the gun steady at any required elevation. The magnets have to be strong because the gun is relatively long and a bit heavy.  Here's the first magnet going into its slot. 🧲 

 

And here are all four glued into their final position surrounding the brass trunnion about which the gun will elevate.

 

And here is the gun breech fitted.  The magnets have indeed engaged with the washers glued on the side of the breech and the gun can now be elevated and depressed by hand and will stay put wherever it's posed. 

 

Now I need to limit the elevation to no more than +65 degrees.  Coming back to @ArnoldAmbrose question earlier about tanks versus SPG's. I don't think any tank has ever been able to elevate its gun to +65 degrees, but accurate high-elevation fire like this is a (the?) defining characteristic of a howitzer. 

 

Now I position a small stainless steel plate at the correct point to prevent the gun elevating any further than it should.

 

Add another brass rod to prevent the gun depressing more than 2.5 degrees below horizontal.

 

So - now we have a gun that can pose at any elevation from -2.5 to +65 and stay there - nice and steady.

Here it is in - roughly speaking - the travelling position.

 

Here in a typical indirect fire elevation.

 

And here at maximum elevation.

 

Don't worry about the fact that the gun barrel is in backwards in these photos (I've just noticed that the bore evacuator is at the wrong end 🙄) because the gun is not yet permanently fitted. It's just sitting loosely in this position for photographic purposes.  I will write a bit more about the gun barrel in a forthcoming post.

 

Anyway the gun is now nice and steady and we are still making steady progress.

 

Can't complain. 👍

 

Bandsaw Steve

 

[JeroenS]

Super cool stuff that you're doing here! And also, thanks for taking us through the thought process as well, I like your clever solutions. 

[hendie]

shouldn't the mast be pointing straight up?

[Courageous]

Great stuff Steve.

 

Stuart