[WIP] Sherman M4A1 Tank (started from various tank steering prototypes)

[Jundis]

Functions look superb!

13 hours ago, SaperPL said:

 I had to increase the size of the whole thing

Looking at the real model, I'd suggest to use the bigger sprockets front and rear, but this would mean a new design for the idler tension mechanism...?

[SaperPL]

Just now, Jundis said:

Looking at the real model, I'd suggest to use the bigger sprockets front and rear, but this would mean a new design for the idler tension mechanism...?

Sprockets at the front are the correct size, but there needs to be an additional sprocket on the side of the one that is actually holding the track for it to look like in the Sherman.

The idler wheel at the back is the problem because it's slightly smaller in the original than the front one, but not as small as the small sprocket is in comparison to this medium sized sprocket that I use at the front. And like you said, the problem is that if I were to make the idle wheel with some wheels on the sides of the tracks and not sprockets, then I would have to change the tension mechanism and it would get ugly.

I suppose I'll either use this small sprocket for the sake of it being built with original pieces or I'll try to design and print a sprocket sized that is in between these two, but it's not optimal. I'm not sure if the size of the idler is that critical though, but I know that this small size difference of it makes that sloped track at the back detail in the looks of the original.

[SaperPL]

Update on the model, I might need to update the topic title...

 

[2ndgen]

Holy wow. The recoil really makes for a special touch, I don't believe I have seen any others with that built in. 

Will be very interesting to see what new building techniques you come up with for the shell. 

[SaperPL]

5 minutes ago, 2ndgen said:

Holy wow. The recoil really makes for a special touch, I don't believe I have seen any others with that built in. 

Will be very interesting to see what new building techniques you come up with for the shell. 

Thanks! I actually want it to be made in supercar model approach where the interior is fully furnished with details and mechanics are somewhat representative of the actual historical tank, but there's some limitation coming from the fact that the hull will have double floor fitting mechanisation, so it's going to be vertically inaccurate in the driver and hull gunner compartment most likely.

I don't think that there's going to be a lot of unique building techniques, maybe apart from how the rear is slanted as there's a lot of complex things going on there both in terms of fitting the RC hub/battery and making the engine compartment historically accurate.

I'm strongly considering making some custom parts though as there is a list of details that are making it hard for the looks. Starting with the hull gun ball mount as the only thing that would be functional will look like this:

I'll probably prototype pieces for this based on the big ball mounts (the ones used in suspension pieces that fit universal joint inside and/or the ones in helicopter swash plate).

Apart from that I'll definitely use a custom sized 8T sprocket:

as the idler wheel at the back. Already have it printed, I'm just short on the track links and not yet 100% ready to pull the trigger on pick a brick order for this project.

Apart from this there's:

• a commander's cupola which I think is impossible to do with what we have in Lego, at this scale,
• gun mantlet cover in the front which is a specifically shaped piece that would be hard to make and attach,
• again at this scale, sprocket/idler fronts matching the looks of the original (but that's just finishing detail to be honest)
• 4L liftarm thick with all pin holes as suspension arm
• Browning .30 cal box/internal part for coaxial and hull gunner

But I'm not really sure if I should go with customising it this much with custom printed parts.

[Lego Tom]

Looks great! Lots of ingenuity!

[2GodBDGlory]

Quite cool! I like that supercar-esque approach, and the functionality looks pretty unique!
Are those black wheel arch pieces 3D-printed?

[SaperPL]

4 minutes ago, 2GodBDGlory said:

Are those black wheel arch pieces 3D-printed?

Yes they are - those are actually ripped from studio, but I have a better model since then, but just didn't have enough time to print it. The reason is that the arch is not available in DBG.

[2GodBDGlory]

2 hours ago, SaperPL said:

Yes they are - those are actually ripped from studio, but I have a better model since then, but just didn't have enough time to print it. The reason is that the arch is not available in DBG.

Yeah, I ripped Sian wheel arches from Studio too for 3D printing, back when I was trying to piece together a multicolored Sian from my collection!

[SaperPL]

6 minutes ago, 2GodBDGlory said:

Yeah, I ripped Sian wheel arches from Studio too for 3D printing, back when I was trying to piece together a multicolored Sian from my collection!

There's this guy on the grabcad which has good quality parts made in solids so you can also edit them in CAD: https://grabcad.com/dk 

For most of the parts I can manage myself, but the panels have complex curves and I just gave up. I would probably have already printed those versions if not of the another part request from eric trax which occupied my printer for some time :P

[2GodBDGlory]

54 minutes ago, SaperPL said:

There's this guy on the grabcad which has good quality parts made in solids so you can also edit them in CAD: https://grabcad.com/dk 

For most of the parts I can manage myself, but the panels have complex curves and I just gave up. I would probably have already printed those versions if not of the another part request from eric trax which occupied my printer for some time :P

Wow, that's really impressive stuff!
Thanks for the link!

[2ndgen]

9 hours ago, SaperPL said:

Thanks! I actually want it to be made in supercar model approach where the interior is fully furnished with details and mechanics are somewhat representative of the actual historical tan

But I'm not really sure if I should go with customising it this much with custom printed parts.

Ya that's a call only you can make.

However it is Lego, nothing is going to be perfectly accurate, but that's sort of the point of it, get as close as you can using creative piece placement, I always find it amazing when something is close that was just not expected to be done with with the parts there are to work with. 

 

[Sentinel]

I know you already built the whole mechanical system and everything, but have you thought about a functional cannon?

[SaperPL]

11 minutes ago, Sentinel said:

I know you already built the whole mechanical system and everything, but have you thought about a functional cannon?

Doesn't make sense to do this at this scale with what I want to make. I want to have the interiors like the supercar models have and there wouldn't be any space inside turret if I had to make a mechanism that shoots some axles or pins. Also the barrel would need to be large diameter or I would have to shoot beside it and still it wouldn't be a strong shooting mechanism at this scale, so that doesn't make sense to me.

[SaperPL]

Another update, some progress with cables and body:

 

[SaperPL]

Non video update - not that much of new things to show yet. Also not that April Fools thing obviously. 
I've tested the round turret sides structure and it works perfectly:

 

And since this is taking shape, I can show off what's the actual plan here:

I based the shape off the welded Sherman model that I could grab from the web, but I've adjusted proportions to match what I had, so it's still slightly stretched vertically.

Anyway compared to the IRL M4A1 it looks fairly OK:

I've placed few orders for DBG coloured parts, but for those that don't exist in Lego colouring I may need to paint them as FDM 3d prints are not as rigid and don't looks so smooth as the original parts. Still a lot of things to figure out.

[SaperPL]

Another update - got some more parts, the suspension is fully on the springs from yellow shock absorbers now. Body is more complete now, but still need to source DBG parts from 3rd party...

 

[SaperPL]

DBG parts are slowly getting here. I sourced some 3rd party panels in DBG for now that these are not available from Lego in DBG at this point:

Not really a fan of how those short curved panels are moulded differently, but I understand that is because of original shape being owned by Lego. Will have to wait and hope till there's a set with those in DBG.

I'm trying to figure out what to do with that angle at the back. I designed my own variant of angled panel and I'm trying to print it with resin printer, but I'd rather figure out how to make it with something available from Lego:

Also I need to figure out what to do with this rear corner of the cast hull here:

[SaperPL]

By courtesy of @eric trax and by our curiosity I can share a size comparison with his Jeep Willys MB (Lego Classic Defender 10317 alt-model):

The Jeep is in 1:12 scale and I think my Sherman is roughly 1:13.5. For reference here's how those compared in real life: