3D - printed Merkava tank

[Conor]

Thanks for the video and the tip with the gluestick - I've considered this but I don't like the mess, and I want it to work without extra stuff. The PEI print bed seems to be doing the job though.

Re the bed levelling problem - my CR10 auto-levels and the Z-offset wasn't directly the problem (I've been doing test prints on the original glass at various offsets and nothing really helped) I'm assuming the bed was contaminated and a deep clean would have perhaps solved it (which would explain why it printed OK-ish on the never used glass surface once the original bed was inverted)

At the moment it is hard at work printing the inner bulkheads, depending on how much adhesion they have I may try going for the underside of the hull again next. I've also ordered the appropriate PU glue, some small files and plastic primer and some desert brown paint, to at least make some attempt at painting the entire machine once it's completed.

[tankme]

I use the glue sticks with ABS and ASA and they work great keeping those materials stuck to the smooth side of my bed. A little warm water, Dawn, and a sponge takes the glue right off. After the bed cools the prints literally slide off without even flexing the bed.

[Conor]

Some little progress

Had to re-start the underside print because the filament wore through on the last 15 layers, and because it was during the night nobody noticed, but at least it's all printed now.

Re-doing the two damaged side prints right now, then the suspension arm mounts, and then I'll bolt the tub together and start work on the track pieces.

[midlife306]

I’ve always used glue sticks for bed adhesion, I’ve tried lots of different brands, some are shockingly bad an act as an adhesion inhibitor.
Best I’ve found is Pritt-stick, you don’t need to wash it off after every print either, if you keep touching it up you can get a couple of weeks out of it before it starts impacting the surface finish on the bottom.
I do a lot of prints that are 8 days plus.
Cheers
Wayne



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[Conor]

That looks pretty impressive!

The bed adhesion is no longer a problem with PEI, but I'm now currently troubleshooting my retraction setting to stop the bowden extruder from wearing through the filament.

This is how far I got today

The other side is currently on the windowsill waiting for the glue to set.

[midlife306]

If your using PLA you need to try this stuff




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[Conor]

If your using PLA you need to try this stuff




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I'm printing in PETG so I'm currently using PU glue I think, which is supposed to be one of the few things that glues PETG reliably.

[midlife306]

dichloromethane is the best thing I’ve found for bonding PETG, it’s apparently the active ingredient in paint stripper so it’s really nasty stuff.
To buy it in the UK you can only get it from chemical suppliers & you have to fill a form saying what you intend to use it for.
I’m not quite sure why you chose to use PETG for this application as PLA would have given a far better result.
Cheers
Wayne


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[Conor]

Yeah, I've read about this too. Don't have a workshop here so hard stuff is out of the question.

I'm using PETG instead of PLA because PLA suffers from heat-related warping in sunlight and warm-ish temperatures outside. I'm intending to use this tank potentially in IR battles and outside running at some point, and with the work involved, PLA was too risky, even if one does avoid sunlight.

There was another person on here who printed the T14 Armata, his PLA prototype also had warpage problems apparently so I'm not taking any chances

Also, hull is more or less complete (rear needs to be printed again) and I've started working on the tracks.

[midlife306]

Sure you can get warpage if you leave something out in the sun, but that problem only occurs when it’s sunny, the handful of days like that in the UK make the issue minor at best lol
I have a proper love hate relationship with tracks, they are one of the few things I do print In PETG & I’ve printed thousands in 1/16 & 1/6.
Cheers
Wayne

Edit, try using a wire brush on each track to aid cleanup after you’ve removed the supports

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