Halo M41 Rocket Launcher aka Jackhammer / SPNKr

This Halo M41 Rocket Launcher does not require an AMS.

 

There are 62 parts split onto 8 plates. The colors I used are Matte Ash Grey (11102), Matte Charcoal (11101), & Matte Dark Green (11501).

 

You can find each of the filaments used in the Bill of Materials beneath this description. 

 

How do I assemble my M41 Rocket Launcher?

Excellent question – scroll beneath the ‘Boost Me’ widget to find the full length instructions.

 

How do I print the M41 with an A1 Mini?

The A1 Mini option was uploaded 1.20.25. As far as printing goes, nothing will change on your end. However, you now have three [3] extra pieces as the top/bottom reload assembly hatch have been split as well as the main grip frame.

 

Will the gun stay together?

This rocket launcher was designed with extremely tight tolerances, but with repeated use, it will ultimately loosen & fall apart. I recommend a 2-part epoxy for large contact points, and a strong adhesive for cracks & edges.

 

Is this a hard project?

I've designed this to be plug-n-play with zero power tools or hardware. However, there are a handful of pieces that have tolerances so tight, you will need to sand them, use a rubber mallet, or both to finish the job. 

 

How much filament will I need?

~976g Ash Grey

~1632g Charcoal

~666g Dark Green

 

How long will it take to assemble?

I would say ballpark 85 hours in total print time, and then an additional 24 hours for epoxy/glue to cure.

 

This was my timeline:

1/11/2025: Finish v0.1 & start printing.

1/12/2025: Rework bad prints & fits – finish v0.2

1/14/2025: Complete major prints & start assembly.

1/15/2025: Print out final peripheral pieces & apply epoxy/super adhesive.

1/16/2025: M41 completely assembled & ready for handling.

1/16/2025: Finish v1.0 and publish to MW.

 

Can I use a bed slinger for printing?

If you're going to use an A1, or eventually an A1 Mini, please consider changing tall, thin vertical pieces to a horizontal position. Don't watch them fall five hours into a print and then flame up my comment section.

 

How do I print in full size?
If your slicing software shows the model at 100%, you would need to scale it up to 142.86% to get a full-size version. 

If it shows it at 70% in your slicer, you just move it back to 100%. The largest object is the main grip frame, so if your build plate can fit the 142.86% scale, you should be home free.

 

What kind of epoxy/adhesive did you use?

I use J-B Weld Pro Size ClearWeld 5-Minute Set Epoxy for large contact areas, J-B Weld Superweld™ Light Activated Instant Glue for edges/cracks, and Gorilla Super Glue Gel for small contact areas. 

 

If you plan on printing my builds in the future, consider picking up the larger sizes to get the best bang for your buck. I'm working on the M45 Shotgun now [1.18.25], and I'm on my 2nd Superweld & ¼ through the Clearweld.

 

Why are certain parts low-poly, like the barrel?

There are many reasons why I chose low-poly or ‘low-res’ prints, but I'll list the important deciding factors:

1. Tighter fits with flat planes: Low-poly surfaces have a predictable and consistent fit when two components are interlocking and pressed against each other. 
2. Increased surface friction: Flat planes generate higher surface friction when in contact with other components – preventing slippage and unwanted movement.
3. Easier assembly: Angular geometry makes it easier to align components manually and guide them into place – following the lines is easy.

UPDATES:

1/19/25: Wrong part uploaded for Ordinance Rear End Block – missing holes on one side. Resolved.

1/20/25: Stock Rail Part 1 missing peg hole for ordinance attachment. Resolved.

1/20/25: Notified of Main Grip Frame & Center Block Support failure with diagonal angle. Unresolved – please adjust to preferred angle if print fails.

1/20/25: A1 Mini print option available.

1/23/25: Barrel 1 Pipe 4 was updated with the proper part.

1/23/2025: Resized Main Grip Frame Insert to prevent snapping.

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Building Your M41 Rocket Launcher

Key

* = Use superglue on the cracks/edges.

** = Use epoxy adhesive on the contact point.

Recommended Equipment

• Big Printer [required]
• 2-Part Epoxy Adhesive [required]
• Super Glue
• Flush Cutters
• Rubber Mallet [highly recommended]
• Needle Nose Pliers
• Sanding Device [Dremel, Drill Sanding Disk, etc]

Exploded Model

Assembling Your SPNKr

The Lower Frame

1. Main Grip Frame Insert into the Main Grip Frame. Beware: Thin sides of the Main Grip Frame.
2. Frame Center Block onto the exposed back of the Main Grip Frame insert.**
3. Main Grip Frame & Center Block Support piece onto the bottom of the Frame Center Block & Main Grip Frame.**
4. Foregrip Frame Peg into Foregrip Frame.
5. Foregrip into Foregrip Frame**.
6. Entire Foregrip [3-piece] set into Main Grip Frame.
7. Stock Frame Part 1 into Frame Center Block.**
8. Stock Frame Cube Peg into Stock Frame Part 1.
9. Stock Frame Part 2 into Stock Frame Part 3.
10. Stock Frame Part 2 & Part 3 into Stock Rail Part 2.
11. Stock Frame Part 2, Part 3, & Stock Rail Part 2 [Back Stock] onto Stock Frame Cube Peg.**
12. Stock Rail Part 3 onto Back Stock.
13. Stock Rail Part 1 pressed down onto Stock Frame Part 1.
14. Stock Rail Cube Peg into the top of Stock Rail Part 1 & Part 2.

 

Under construction…

 

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