M739 SAW Build Guide

josephaguilarsanch
Jun 7
5 min read

When you've got an Appetite for Destruction, the M739 is The Answer

Full description and file set available on the main product page.

The SAW features a button operated drum magazine with functional trigger action.

This Build Guide will list the following:

Required materials to complete the project
Assembly videos to walk you through the assembly process
Recommendations for Print Settings/Orientations for certain pieces

Any additional questions you have concerning the building of this model can be sent directly to me via the contact page on my website

Build Requirements

3D Printer: The full print measures ~1.15 meters. This is accurate to in-universe scale. The print has been sliced to accommodate printers as small as 256^3mm.

2-3 Rolls of PLA (I prefer SUNLU)

1-2 Rubber Bands

1 Spring

Assembly Instructions:

SAW Assembly

The SAW is comprised of 3 major components, the core body, the outer body panels and the drum magazine.
Body A - E as well as the grip/stock all slide together utilizing any number of the Master Pins Type A and B. All Seams have been hidden along natural geometry and behind body panels as best as I was able.
The Trigger and Trigger Stop must be placed inside the Grip before core body assembly. Hot Glue a spring to the rear face of the trigger to ensure you will be able to pull the faux trigger.
Place the Top Barrel Insert and Barrel Brace Rear Inside the Bottom Barrel Insert before sliding in the Top and Bottom Barrel.
You can also place the Strap Ring inside of Body A at any point, you will have to flex the ring to get it to fit inside the holes.
Most Body panels fit over the core body but have no fasteners, adhesives will have to be used to secure the body panels to the core body.
Body Panel D will fit over the top of the body but the arms can be flexed into place. Body Panel H slides into place on the natural "railing" on the top of the core body stock.
The correct order to assemble the Drum Magazine is as follows
- Place the Drum Center and Drum Rear Cap together with the drum button sliding loosely in the railing.
- Place all 4 lever arms in the Ammo Feed and secure them with the lever pins.
- Place the Ammo Feed into the Drum Rear Cap with the lever arms poking through the drum button. The two cross arms between the levers should be what is being pushed by the button.
- At this point you can now attach rubber bands to the end of the lever arms. This will force the arms together and the button outward. Pressing the button should pull the levers arm towards the center
- Now you can enclose the entire assembly with the front cap. This front cap can be removed at any time to access the ammo feed mechanism/rubber bands.
- Now you should be able to push the button insert the drum mag and release the button to ensure the hooks catch the circular pegs in the SAW to ensure the drum magazine does not drop out
- There is also a fake bullet insert you can place in the front hole to simulate a drum mag full of ammunition

General Printing Tips

Make sure to calibrate your XYZ steps on your printer before printing!!

Because this print is so large, any mismatch between the X Y and Z axis accuracy can add up to 1-2 mm of error over the whole ~4ft print. The core body is designed to be printed verically while many of the body panels are likely to be printed horizontally, meaning that a non calibrated printer could cause the panels to not fit properly over the body.

This can be avoided by calibrating your XYZ steps on your printer. To get the best accuracy for this test, I would recommend print your calibration cube at the largest scale that your calipers can measure. For example, getting a 60mm cube within .01mm of accuracy is going to be more accurate than getting a 20mm cube to that same .01mm of accuracy.

The pieces are not pre-oriented so you will have to adjust them to ensure they are in an orientation more optimally for printing (flat surfaces touching the build plate). Additionally, for pieces that have no ideal flat surface, I highly recommend using the Cylindric Custom Support downloadable plug-in for the Ultimaker Cura Slicer. It allows you to place custom supports on parts to ensure that you can get much safer and reliable prints on parts with odd geometries. Some of the examples below will show these custom supports, you will need to add them, or something similar to your own prints. These supports will also allow you to add more stable bases if your printer is not great at printing tall thin objects. Similarly, I would recommend using a 10-15mm Brim to ensure good build plate adhesion.

Optimal Print Orientation

Load Bearing Pegs/Pins

All Pegs/Pins should be printed such that the layer lines align with the long axis of the pin, this will make them much less likely to snap off within the pieces due to any bending force.

General Print Orientations

I've combined multiple files into one build plate in order to show multiple orientations at once, I do not recommend printing multiple pieces at once as it will increase overall print time due to excessive travel time, and introduces multi-print failure risks.

In general if you see any circular or semi-circular arcs on any of the prints, you can place a support blocker to reduce the overall number of supports. Arcs like that are typically self supporting and print find without supports.

As you can see, most of the core body pieces have flat face that can be used to print the piece with minimal supports.

Most of the Body Panels should be printed on their side or upside down, but some can be printed vertically as shown.

The barrel should be printed upside down with some additional supports to ensure the rear face that is inserted remains smooth

The Ammo Feed should select the beveled corner as shown to reduce supports and ensure the levers can smoothly translate inside the ammo feed.

The lever arms should be printed as shown to ensure that the arms don't snap due to the rubber band pulling on their ends.

Personal Build

I personally printed the prototype at 65% to quicken turnaround time and due to my own small frame. Definitely turn the sound on in the video, the sound of reloading the magazine is very satisfying!