PRESENTING THE ANH HAN SOLO BLASTER HOLY GRAIL...

Prop Runner

Sr Member
Thanks for that , Andres.

Another thing to consider with the knurling on the found part is that this suppressor was painted after whatever heat treatment and finish it was originally subjected to. The paint has worn off on the sharp ridges of the knurl, and because it was originally a liquid, it likely produced a small radius on the bottom of the knurl cut which disperses reflected light. For these two reasons, the knurl cuts appear darker and deeper between the exposed ridges. In the unpainted hero part, you can actually see the bottom vertice lines between the sharp ridges, giving the knurl a lighter and therefore shallower appearance.

To illustrate this:

knurl.JPG


Lighting is everything, folks. :)

- Gabe
 

kurtyboy

Master Member
RPF PREMIUM MEMBER
You forgot to add that its going to be illegal to ship replicas of this piece to some countries :lol

Originally posted by Prop Runner@Nov 2 2005, 02:37 AM
It finally arrived today: a near-perfect specimen of an aerial WWII German MG81 machine-gun booster/flash suppressor.  Several disclaimers before I begin:
  1. It's on loan from the owner.
  2. It's NOT - repeat to infinity - NOT for sale.
  3. It won't be cast in resin.
  4. It WILL be replicated soon as a functional, 1045 medium carbon steel machine-gun part, but do NOT - repeat to infinity - NOT PM or e-mail me requesting to get on an interest list.  Appropriate announcements will be made when it's time.
And without further ado, the photos:
[snapback]1108006[/snapback]​
 

Prop Runner

Sr Member
Originally posted by kurtyboy@Nov 2 2005, 01:27 PM
You forgot to add that its going to be illegal to ship replicas of this piece to some countries :lol
Actually, it's strangely appropriate that no MG81 parts should travel by air to the UK: most of the ones that already attempted the journey crashed into the North Atlantic... ;)

Ironically, the ANM2 booster heatsinks originated the UK, so the customs declaration should read: "Returning historic British war relic to rightful owner" :)

- Gabe
 

Skyler101

Sr Member
So... what are you saying Gabe, that the part was not from an old fire extinguisher, or the grips from an old motorcycle? Im not impressed at all... LOL..

-Skyler101
 

Serafino

Sr Member
Gabe, very good point about lighting of course.

I think it would be very revealing to line up the two examples enlarged and overlaid in Photoshop and play with the contrast of the pic of the found object.

This may well show the two to be potentially much closer than they appear.
 

Treadwell

Legendary Member
RPF PREMIUM MEMBER
Sweet photos. Quite an historic time here on the board.

Many thanks to everyone involved in the discovery. With such great results, I couldn't be happier about being wrong.
 

Darth Lars

Master Member
Very good photos of the found part. :thumbsup

Say, could the cone have been welded on onto the muffler or do you think it has been machined as one piece? I am interested in if there are any differences in the transition between muffler and cone between this part and the real prop.
 

Prop Runner

Sr Member
Originally posted by Darth Lars@Nov 2 2005, 04:57 PM
Very good photos of the found part. :thumbsup

Say, could the cone have been welded on onto the muffler or do you think it has been machined as one piece? I am interested in if there are any differences in the transition between muffler and cone between this part and the real prop.
[snapback]1108379[/snapback]​
Good question. This was always an established assumption, but one based on a false comparison between the hero suppressor and the GK M9 suppressor, which is rolled sheetmetal and is TIG welded in 2 places. I have no doubt in my mind that the the hider and booster are turned frm the same stock steel rod. Both my tactile analysis of the internal and external surfaces and the high tolerances I measured lead me to this conclusion. Based on photos I've seen of the MG34, MG42, and some Czech and Russian suppressors, I'm sure they aren't welded either. Could an MG34/42 expert chime in and confirm?

And since you asked, I thought it would be appropriate to post another historic photo: the hero found part and GK found part side by side:

MG81_M9.JPG


The welds on the M9 hider should be very obvious.

:)

- Gabe
 

moffeaton

Master Member
RPF PREMIUM MEMBER
MG81_M9.JPG


That part above your fire extinguisher nozzle is an attachment to a Brazilian watering can from the 1960's. My friend's baby-daddy said so.
 

Prop Runner

Sr Member
Originally posted by moffeaton@Nov 2 2005, 07:16 PM
That part above your fire extinguisher nozzle is an attachment to a Brazilian watering can from the 1960's. My friend's baby-daddy said so.
Not sure what a baby-daddy is, but I challenge you to show me the rusty original discovered by Jeff Ritzman while on a prop hunt in Sao Paulo. If you can, I'll publicly recant and add you to my List of Heroes. ;)

- Gabe
 

Prop Runner

Sr Member
Some updates:

I've updated the 3D CAD model. In fact, I decided to start from scratch, since the older one is essentially a completely different part. After visiting my trusted machinist, where we used bore gauges and telescope gauges to nail the difficult internal geometry, we determined the following:
  • The thickness of the conical flash hider is NOT uniform - it's twice as thick at the base than at the front end
  • The 8 rows of 6 holes along the flash hider are drilled PERPENDICULAR to the central axis of the part. In other words, when you line up opposing holes, they are perfectly circular and concentric.
  • The internal thread is a Metric fine pitch M profile (M30x1, class 6H)
  • There are 85 knurl cuts (the exact profile will be measured by a knurling gauge)
  • There are 16 scalloped cuts, whose lands line up with the flash hider hole rows
  • There are two 5 mm-diameter opposing vent holes (unthreaded) that are slightly off the scalloped cut-flash hider hole row imaginary plane, by no more than 2-3 degrees. I believe this was not the design intent, so I lined them up with the imaginary plane; also, since the vent holes are smooth-walled, it raises the question of what socket head screw was used there on the prop - the screws either cut into the holes or the holes were tapped to accept a 5.5 or 6 mm screw
mg81_side_s.JPG


mg81_iso_front_s.JPG


mg81_iso_thru_s.JPG


mg81_rear_iso_s.JPG


The threads in the two cutaway views below are "virtual," so imagine triangular ridges coming out from the border of the yellow area:

mg81_cut_iso_rear_s.JPG


mg81_cut_side_s.JPG


The unknowns I'm currently confronted with on the road to replication are the grade of hardened carbon steel and the finish. Below are examples of standard finishes for carbon (non-stainless) steel:

Parkerization, which is identical to the finish on the GK hider:

[image]http://www.cpmuzzlebrakes.com/images/colobrake02.jpg[/image]

There's also oil-quenching, which gives a rich black finish:

[image]http://images.amazon.com/images/P/B0007R6QOA.01-A8QVA2VP18VAT._SCMZZZZZZZ_.jpg[/image]

Black-oxide finish:

[image]http://www.globalspec.com/NpaPics/77/172473_121020032050_ExhibitPic.JPG[/image]

And blued steel:

[image]http://www.airgunsus.com/pics/rws2652.jpg[/image]

If people would rather paint their replicas, or keep the look of unfinished C-1045 medium carbon steel, they could simply clear-coat it to ward off rust. Here's what it would look like:

[image]http://images.amazon.com/images/P/B0000AX4I5.01-A1787XOD7Q2I4M._SCLZZZZZZZ_.jpg[/image]

I'll be consulting with my machinist and a few gunsmiths to determine the correct steel, heat tratment, hardness, and finish. One thing is certain: the original was NOT blued - that process was reserved for civilian and sporting firearms, not military, and is more an aesthetic finish than one that resists corrosion.

Feel free to discuss the finish posibilities and if there are any gunsmiths in the house, your informed opinion on the steel would be most welcome. Drew, where are you when we REALLY need you? ;)

- Gabe
 

OdiWan72

Master Member
RPF PREMIUM MEMBER
Gabe, your skills in creating CAD models are AWESOME.....

My hat´s off to you :thumbsup

Markus
 

amish

Sr Member
As ObiWan72 said above me, your CAD models are awesome. Personally, and I have no real knowledge about this, but parkarized sounds right for the part.

Otherwise, tremendous work :)

On a side note, how long does it take you to make these CAD models?

Take care.

Tom
 

Gigatron

Sr Member
Holy cr@p Gabe. Some of those CAD renderings look like photographs :D :thumbsup.

I'm probably going to be spending more money on upgrading parts (between this and the obi saber) than the things cost me originally.

-Fred
 

Darth Lars

Master Member
Great CAD drawings. Now, change them to reflect the prop. ;)
I think it is clear that the knurling on the prop is more shallow and the notches (chamfer) on the back is less pronounced. I think the angle is the same on Boba Dept's muffler though.
Me and Boba Dept noticed the knurling was not perfectly straight on any muffler or hider that we could study in detail. The prop's is almost straight, but not completely. However, I think replicating that tiny tiny detail would be too difficult and not many people are going to like it anyway. :lol

As to the finish.. a rehash from earlier threads:

Martin (owner of the first hiders/mufflers) wrote:
In regard to the finish, most of the flash hiders were painted black, but some were parkerized.
David/Boba Dept wrote:
The parkerized finish is the way to go.
I have a booster with that type of finish and it looks perfect.


I think it looks brown in some pics and black or grey in others. It is definitely lighter than the Mauser. Then.. what finish is the Mauser and bull barrel? If we know that, then we know that is wrong. ;)

I think it has been established that the muffler insert was used to attach the hider to the bull barrel. The question is how. I noticed in side pics of the prop that gap between the hider and bull barrel is larger in the bottom than on the top.
Could a small nut have been inserted between the muffler insert and the inner wall of the hider? In that case, would it have been possible to have used that to tighten the bolt against the insert against the bull barrel against the front opening of the muffler?
I assume there is no side hole on the insert ...
 

Prop Runner

Sr Member
Originally posted by Darth Lars@Nov 4 2005, 04:40 PM
Great CAD drawings. Now, change them to reflect the prop. ;)
Thanks for the comps, guys. It means a lot to hear... But like Darth Lars, some of you are hard to please. :lol

Here you go:

hero_compare_cad.JPG


Please ignore everything from the knurls and to the right, as the perspective is off on the CAD - it's impossible to match false-perspective to a real photograph, but I did the best I could to match the scale, and as you can see, I tweaked the scalloped cuts to reflect A) narrower & shorter cuts, and B ) rounder edges.

I think it is clear that the knurling on the prop is more shallow and the notches (chamfer) on the back is less pronounced. I think the angle is the same on Boba Dept's muffler though.
I made the knurling a bit shallower in the CAD model, but when I export it as a 2D image, the high contrast lighting makes everything look deeper. So please don't look for 100% match-ups between the CAD knurls and the real-world knurls. I also corrected the chamfer to be a bit shallower - to me they line up now. I don't know about David's part and I'm not looking at ANY older replicas as reference material - what's the point? They're ALL wrong.

Me and Boba Dept noticed the knurling was not perfectly straight on any muffler or hider that we could study in detail. The prop's is almost straight, but not completely. However, I think replicating that tiny tiny detail would be too difficult and not many people are going to like it anyway. :lol
I agree. No two parts will have exactly the same knurling, period. Not the originals, and certainly not the replicas. I'm not going to deliberately attempt to create unparallel knurling, but that may happen anyway due to the nature of the operation.

As to the finish.. a rehash from earlier threads:

Martin (owner of the first hiders/mufflers) wrote:
In regard to the finish, most of the flash hiders were painted black, but some were parkerized.
David/Boba Dept wrote:
The parkerized finish is the way to go.
I have a booster with that type of finish and it looks perfect.


I think it looks brown in some pics and black or grey in others. It is definitely lighter than the Mauser. Then.. what finish is the Mauser and bull barrel? If we know that, then we know that is wrong. ;)
From the best photos at our disposal, it can be agreed that the Mauser was deep blued. I personally would also go with parkerizing, perhaps a darker gray than the example above or the M9 suppressor. In the Chronicles and other photos, the suppressor is almost as dark as the Mauser.

I think it has been established that the muffler insert was used to attach the hider to the bull barrel. The question is how. I noticed in side pics of the prop that gap between the hider and bull barrel is larger in the bottom than on the top.
Could a small nut have been inserted between the muffler insert and the inner wall of the hider? In that case, would it have been possible to have used that to tighten the bolt against the insert against the bull barrel against the front opening of the muffler?
I assume there is no side hole on the insert ...
You assumed correctly - there are no holes period except the center hole. If a nut was inserted to capture the screw (good thinking. :) ), then it had to have been a very thin nut and somehow held in place against the inside wall of the booster while the screw was turned. Not sure that would have been possible in such a tight area... If the booster cone (insert) was originally used as an adapter between the booster and the bull barrel, I'm sure epoxy could have been used. The screw really doesn't play a significant role if this part was indeed used, so I could have been wrong in my theory. It's just that if you can see the edge of the bull barrel in the booster hole, what the heck is that screw grabbing? It makes no sense. However, if the booster cone was a bit loose inside the booster, then the screw may have just stablized it. Then, after it was lost, something would have had to be inserted on the other side to re-center the bull barrel, but obviously the booster/hider was still off-center.

I'll be visiting my machinist again in an hour to go over some details and then I'll finish up the drawing. After replicas have been offered, I'll share the drawing with anyone who wants to make their own. :)

- Gabe
 

Serafino

Sr Member
Gabe, speaking out of my ‘range’ again, the CAD knurling looks very promising to me. I think the reason it appears to go too high on the ‘shoulder’ is that the shoulder is even rounder on the prop, the knurling fades/becomes shallower due to the decreased diameter from the rounded shoulder–which may explain the weird effect of the knurling appearing longer in the middle and shorter above and below on the prop part.
 

steveday72

Well-Known Member
IMHO, here is what I think about the finish:

Parkerized is far too grey to match the MG81 booster/flash hider.

Black Oxide is not a thick coating, but actually treats the surface (and microscopically, the sub-surface) of the metal, so it would not chip like in the genuine MG81 booster. You can chemically brighten a Black Oxide part, by soaking it in something like "Kaboom" - it's probably the ammonia. Or it can be sanded/bead blasted off. But whichever way it happens, it won't chip off, because it can't.

The chipping of the surface we see in the photos is a very important clue to the finish of the booster assembly.

Ask the gunsmith if they ever sprayed parts with black enamel (like they did with cast iron stoves), because that's what it looks like to me.

Great work

Steve
 
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