Scratchbuilt Bushmaster PMV 4x4: now with paint!

[GMK]

On 1/3/2021 at 9:51 PM, dodgem37 said:

Super work.

 

Sincerely,

Mark

Thanks Mark, I appreciate your continued support. 

Apologies for the wall of text, but here’s a bit of background to the wheels.

 

My original plan (2019) for the model was to use the complete suspension from an off-the-shelf M-ATV kit, with the remainder being scratch built. 
 

Thanks (?) to lockdowns various, I embarked on the journey to learn CAD in March 2020. As I learned more about how to use CAD, the number of parts intended to be borrowed from the M-ATV kit shrank. 
 

The M-ATV tyres are correct for the Bushmaster, so remain part of the build. The hubs, however, aren’t correct, so I modeled & printed replacements. 
 

The inserts for the hub rear were, until yesterday, still on the PMV Bill of materials. It was at that point I realised I hadn’t validated some aspects of my design. 
 

The M-ATV parts place their alignment pegs at 3 or 9 o’clock, whereas I had mine at 12 o’clock. Notice anything about the respective axle diameters?
 

Yep, the PMV parts I’ve done up have a much smaller diameter than their M-ATV counterparts. My mistake was to transfer the distance from the alignment peg to the edge, rather than the centre, of the axle. 
 

 

This left the weight of the wheel be supported by the alignment peg, but at the correct ride height. Correcting the difference on the axle would lower the ride height. Hmmm. 
 

After a little bit of thinking, I copied the kit hub inserts in CAD, but offset the axle upward by about 2-3mm. 
 

 

So, jagged it! The offset axle avoids altering the suspension geometry, maintains the correct ride height, and further reduces the usage of M-ATV parts in my build. 

[GMK]

Mocked up the base today, using a 12mm sheet of MDF cut to 500 x 200mm/~20” x 8”. Countersunk holes for the M6 bolts were drilled, then the model test fitted. 

From the front. 
 

 

When mounting properly, the M6 nut will be run up the bolt and tightened again the M6 nut that’s been epoxied into the differentials themselves, creating a mechanical lock. That way, the weight of the model is borne by a pair of bolts, rather than scale. 3D-printed suspension units. 

 

From the rear:

 

 

Overall. 
 

 

Once fine tuned, the suspension will be glued up, painted, and fixed to the model. 
 

Found a random video that provides an overview of the truck, with broad pretty broad Australian accents!

 

 

Edited January 6, 2021 by GMK

[mambodan72]

Love it!

 

[GMK]

Mucking about with minor parts today. 
 

Firstly, the wire cutters were CAD’d up. These are located in the upper corners of the windscreen. I’ve modelled them in the folded position. 
 

 

Without the ECM antenna. 
 

 

Then it was time for the front (small) & rear (large) crew steps. 
 

 

 

On to the machine gun Platt swing mounts. 

[GMK]

2 hours ago, GMK said:

On to the machine gun Platt swing mounts. 

 

 

Which didn’t take long. Still need to model the cradles & ammunition holders, the the swing arms themselves are more or less done. 
 

 

These will have MAG58/M240/GPMGs mounted. 
 

 

Mirrored & printed the wire cutter for the RHS.

 

 

[dodgem37]

Good show.

 

''MAG58/M240/GPMG'

Popular weapon.

 

I'm surprised the air brake/tire inflation hose isn't armored.  But maybe that's not done any more.

Sincerely,

Mark

 

[GMK]

22 hours ago, dodgem37 said:

Good show.

 

''MAG58/M240/GPMG'

Popular weapon.

 

I'm surprised the air brake/tire inflation hose isn't armored.  But maybe that's not done any more.

Sincerely,

Mark

 

You’re right, Mark. It’s one of the most popular 7.62 NATO machine guns. Heavy to carry, very effective when employed correctly. 
 

Re. the CTIS, the air hose is a metal segmented hose to resist terrain & vegetation-induced damage, but it is unarmoured, as you say. Maybe it figured that it’s just a small target?

Need to adjust the MAG58 I bought from Shapeways & add the trays for the ammunition boxes on the left side of the cradle. 
 

[GMK]

A return to work = a decline in model productivity. Most of the designs are largely complete, or at least blocked out, requiring final adjustments & details. 
 

The Platt swing mount currently looks like this:

 

 

 

The EOS R-400 remote/protected weapon station was next. 
 

 

The PWS will be fitted with a .50 cal M2 with Quick Change Barrel. 

Edited January 17, 2021 by GMK

[GMK]

Luckily printing is set & forget! Here’s the first iteration of the PWS.

 

 

 

[dodgem37]

Yessiree,bob.

 

Sincerely,

Mark

[mpk]

Amazing! 

[GMK]

12 hours ago, dodgem37 said:

Yessiree,bob.

 

Sincerely,

Mark

 

10 hours ago, mpk said:

Amazing! 

Thank you, gentlemen - I appreciate the feedback. 
 

The time spent on drawing up the cradle was worth it - for a MAG58!

 

 

Unfortunately, there’s no commonality between the the cradle for light/medium machine guns & the 50 calibre. 
 

 

As can be seen above, the cradle for the .50 is pretty beefy! Hopefully I’ll have time to finish it this week. 

[GMK]

As always, it’s best to confirm assumptions *before* tweaking a design. 
 

The ADF uses the M2 Quick Change Barrel .50 calibre machine gun, not to be confused with the US M2A1 Quick Change Barrel. The former has the barrel alignment keyway recessed on the barrel, the latter with the keyway cut into the perforated barrel support. 
 

Initially it was thought that the weight of the 50 cal & associated ammunition would be too heavy for the PMV. Turns out it wasn’t. 
 

The 50 cal is fed direct from the open topped ammunition box, with the lid attached to the side of the box to keep it out of the way. 

So, first things first, model the upper row of ammunition. 
 

 

Then modified the ammunition box to remove & stow the lid, then add the bass relief ammunition itself. 
 

 

This better represents the PWS configured to support the .50 cal/12.7x99mm.  
 

Added the sensor pack & sun shade. 
 

Edited January 23, 2021 by GMK

[GMK]

Just closed off a major work package, so have a little of my life back. Time to break out the resin printer. 
 

This will be the test print. 
 

 

So, let’s see how it turns out. 
 

 

Less supports. 
 

 

Not 100%, but still very high quality. May use the resin printer for more detailed parts moving forward. 

[GMK]

With some inkling of the resolution available from the resin printer, I tweaked my CAD to incorporate more detail. 
 

 

Reprinted:

 

 

Some cleanup required, but good overall.