Unspeakable Acts on an unsuspecting Sherman...

[Rob1970]

That is correct Sir! Not badly drawn at all.

Weeeeelll.... actually I was wrong... and you were too?

It goes like this...

In this cross-section, the orange bit is a small plastic barrel which grabs the main barrel. At the back side there is a little lip that stops the ring/gasket (in red on the drawing) from sliding further back. The barrel should only barely touch the gasket. So it goes in about 10mm.

Which means the rear end of my Firefly barrel needs to be shorter... and the part where is gets fatter needs to be cut as well. Oh joy... machining without a lathe...

*deep breath*

To Be Continued...

TTFN,
Rob

[Rob1970]

A deep breath, a really fine but sharp razor saw and a short prayer later...


First shifting the thick end up (as it turns out) 3.5mm. Slow cuts along the thin end of the barrel into the thick end, which I already scored all the way round at the right spot. So it's cut from the back, cut from the top, cut from the back again... until I was almost all the way around, and then a very fine keymaker's file did the rest.


The thin end that goes into the airsoft mech box I shortened in stages. Cut and sand, re-assemble, test fire, disassemble, cut again, re-assemble, test fire.

Did that until the gun fired fine, except by now the gasket had gotten a small tear and I was losing some power. But new gaskets have been ordered, and I probably need to fatten up the thin section juuuuust a tiny bit to make it more snug. That I will do with layers of CA, but only when the gasket is replaced.

But there is hope...

To Be Continued...

TTFN,
Rob

[PainlessWolf]

Rob!
I considered whether your fine illustration from earlier had the end of the barrel stop where the rubber bushing was illustrated and assumed it did. We all know what assume does to us. ;o) The bushing definitely goes on the end of the barrel where it meets the mechanism. Apologies for the lackluster scrutiny of your artwork sir. ;o)
regards,
Painless

[Rob1970]

Let's talk about welds. Awesome welds...

\

*sigh* No, internet. Awesome Welds... not Orson Wells... altho he was awesome...

As you could see earlier in the thread I did some weld beads with my 3D pen. This pen is an -original- first issue 3Doodler, which I bought from their kickstarter campaign. The first ever 3D pen. Big, bulky... not the lightest.

I was having some trouble getting nice beads in some of the tighter corners, when SWMBO casually remarked; "Didn't you also have a smaller one?"

And yes, I do... picked up on AliExpress a while back, and put in a drawer... forgot all about it.

This one; https://www.aliexpress.com/item/33020992274.html. Awesome little thing, with a very pointy ceramic nozzle and it can be set to various speeds and temperatures.

So I decided to try it out in a new way. Stick-on welds beads. So... experimenting we will go...


I have a strip of 1mm thick copper, as a heat sink...


Wrapped it in normal paper, two layers on the top and some pencil lines to guide me. The extruded fillament will stuck to the paper just enough to keep it in place, but the work will peel off.

phpBB [video]

A little experimenting with temperature and speed with which the pen feeds the filament later, and we are ready to go. Drag the pen back with a little back and forth judder (and a tight zig-zag for the wider beads) and with some practice I got some very acceptable weld beads... Now, I have plenty of filament scraps (PLA only, more on that later) so I can was a lot to get enough good bead to work with.


Narrow and wide beads. With a good flow in my motion I can get up to 5 inches of nice steady weld bead, and when you peal them from the paper the bottom is flat and ready for glue.

These were done with PLA wich does not glue to ABS all that well. CA glue would work, but a friend of mine does do a lot of work with ABS in his 3D printer, so he's mailing me a load of scraps. Those should weld up a treat to the ABS of the Heng Long hull with some MEK.

Next experiment; making inside corner weld beads, as soon as I find some 10x10 (or smaller) aluminium angle strip to use as the angles heat sink. I am sure I've got some -somewhere-...

To Be Continued...

TTFN,
Rob

[Rob1970]

This was a triumph.
I'm making a note here; "Huge success"
It's hard to overstate my satisfaction.

I can indeed make inner corner weld beads that look pretty darn convincing.


All it took was a small piece of aluminum 10x10 corner profile lined on the inside with painters tape. Work like a charm. And soon I had a tankload of weld beads... At slow feeding speed I could even make very small ones.


Perfect size to put around the vents. And the bigger ones were great size for the hatch bumps.


The flat ones laid down nicely on top of the hull... I used the PLA ones I already made and just attached them with CA glue...


... and I pretty much ended up replacing all the milliput welds with PLA self-printed welds... It goes on nicely, and when you have a round bit (like on top of the old bow MG mount) a flick with a lighter will soften the bead and lets you press it in place. With the vents the beads were thin enough to be bend without heat.

So yeah. Happy. I think I deserve cake. I hope the cake is not a lie...

To Be Continued...

TTFN,
Rob

[NAB]

This was a triumph.
I'm making a note here; "Huge success"

Sent from my KB2003 using Tapatalk

[HERMAN BIX]

What a bloody smart gadget !!
Old Orson would be equally intrigued !

[Rob1970]

So, with the decision to do a complete hull for the Firefly -and- the M4A3 105MM, I need to address the back plate of the Firefly. New door, moving the exhausts and putting on some air filters and a towing thingy...

Also; my ABS filament came in, so I might as well try some of that on the welds on the engine door...


Yes, turns out ABS weld beads are even nicer... I am happily amazed.


yeah, rrrreally happy. The ABS weld beads just blend in on the ABS sheet with a little touch of MEK.

To Be Continued...

TTFN,
Rob

[EAO]

Rob,

Wow, just simply Wow!

Cheers,
Eric.

[EAO]

Well, Rob, I am glad you aren't headed for oblivion on a BB shooting spree! I suppose, however, that I am the last one on RCTW to know that there even is such a thing as a 3D pen.

Our good Herr Dr.,

I too have never heard of such a tool! Perhaps, I'm the tool?! Or, maybe it's just because we're Wisconsinites?

Cheers,
Eric.