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SD Studio Lawgiver Mark II & Model Gun


I thought I will post a build log of a kit I bought from SD studios. I recently proposed to provide a new version of a Lawgiver version of my Blaster Core sound board.
It's almost done, that build log is meant to serve as a visual guide for the install of the electronics, for those who will do it themselves.

mine has a few little variants from what SD has proposed for his fully built LG but overall, the principles remain the same. The main difference is that I used a model gun as I wanted a display piece with realistic looking bullets. I know, it's a pain to load and clean but I don't expect to use PFC aside of a couple of demos. Another LG with an airsoft is planned too anyway.

Also, this thread will help (I hope) people to patient a little bit more and see the possibilities of the electronics.

so... I started that project when the kit was first sold, then paused cause I didn't have a place to spray paint... back at work on it again. I finished blaster core v4 3 weeks ago and had the plan to port the LG firmware on it, and things converged pretty fast in the past 2 weeks, after tuning specs with SD studios.

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Long tribulations to source a beretta M9 model gun to France, what a mess. I ended up in japan with semi ghost company and couldn't get the shells, then sourced the shells in the UK but now I'm almost sure they are too short. Designed for a M84, juuuust a bit shorter, the new PFC won't bang properly as they don't perforate, so they bang, blow back but no smoke and no sound LOL
[actually leaves some expression possibilities for the BC4]

Recent pics of stuff I did a year ago (already ? really ?)

satin paint job is decent but perfectible

ammo clip in place with foot part

threaded holes for slide attachement

adding the greebly on the reload mechanism. Per discussion with SD, a 2 pin system was a good solution (and JB weld)

Glued !

Still have to paint the second half of the gun. To protect the silver area, I used Mecanorma tape, old school PCB design technique to protect what you don't want to etch. Good tack, removable residues (very little) and paint/water proof.

Then maskol (latex paint) to seal thin tape with blue painter's tape and ready to go !

another view

mag release greeblie. Threading both sides and giving a clean shave cut to the knob with the lathe.

4mm M3 set screw is perfect for the job


Lever after 2 coats of silver with the airbrush (I keep practicing) : invisible pins (almost... the camera sees them but I don't)

I finished the paint job on the remain half. As I'm not sure of the paint I used for the 1st one, I took the risk to add one extra coat of satin black to ensure "color" (if I can say so) and mosly gloss level are the same.

right side shell was too thick for my model gun slide. That's the last trimming required to have the kit fitting that very gun (very few mods, really, just dremelling here and there)

installing clear styrene backing so that I have something to glue the leds on later.

Installing some wires, checking length

Speaker install - to be tested but the eye piece could provide a small rear resonant chamber

Hall effect sensor that I'll use for the main trigger and ammo clip detection

Experimenting with dyed resin for the red windows (SD idea). Didn't find the right pigment but that glass stain / paint seems perfect. It's solvent based so it should mix well with the glazing resin

First test is too weak, second one is good but the color pigments have "migrated" in the corners. Still, the shade starts to be nice

To be continued. I should get prototype PCBs for the side leds this week. Leds have been selected and tested individually, so I just need the panels to start the actual and final wiring of my prop, and validate the electronics, then ship a prototype.

some progress. Converging quickly to the final thing... Nice, after a year

Side leds. White SMD leds, low profile enough to fit under the gun even with the PCB.
Those white leds have a large beam with the additive that produces the white light. The whole yellow area becomes white with a large angle.

and they are SUPER BRIGHT (even at 10mA)

[img width=462 height=768][/img]

diffusion test with 7-segment display filter
as expected, too close = beam / spot

at a few mm of distance, you start diffusing.

Assembling some side panels PCBs for those leds

let's start the assembly / wiring. I frosted the clear styrene backing with 240 grit sandpaper to improve initial diffusion. I also inclined the PCBs to avoid a direct light beaming thru the windows. Board is secured with double sided foam tape. You'll notice the flashing PCB extension so that I can keep working on the firmware without disassembling anything.

tidy wiring :045:

with the gun installed

Rear lights. Assembled on some perf-board that I also use to install the hall effect sensor of the trigger (those are part of my customization, SDS full builds will use switches which isn't worse or anything). I just love those sensors, but they for sure complicate the install an require some more wires to be routed.

Made some more space on the trigger mechanism, as the magnetic sensor a the perf-board + wires were eating up a couple of precious mm.
I also drilled the rod to install the magnet.

Second panel on the left half of the gun

I made the install at 99% on the right side of the gun. This way it's easy to disassemble.
The aux. switch (ammo selection) is at the top of the grip. The magazine sensor is also a magnetic sensor with a small magnet installed in a recessed area of the mag. It will be painted "gun metal" later to have it merely invisible.
To activate the aux. switch, you just need to squeeze the handle in a certain way.

Almost there. Missing the red windows. Off to the hobby shop today to find some alcohol based inks to dye the resin.

The bullet view with the slide locked is what made me choose the model gun for that prop.


Battery setup. Works for both 9V battery and 2 x li-ion cells (14500)

switch isn't final, not happy with the placement of this one, I'll fix this today

Slide rear mod : the second screw of the rear block can't go deep in and as the slide is fibered plastic, no way the threading can resist to the blow-back on the long term. I don't like to epoxy parts that might need service, so I placed a M3 self threading insert with JB weld.

then moded the 6/32 screw with a M3 insert, to keep the look of the original screw.

Time for filling the side windows (ammo leds)...
scary operation for me as I'm a resin NOOB

I found some good alcohol based inks, which mixes well with resin : alcohol evaporates and leaves just the pigments, compared to the glass stain/paint which has some transparent resin/linker which doesn't harden like the glazing resin itself. The result of my first try was nice but I needed too much glass paint to get the right shade and transparency, the resin took ages to cure and isn't hard enough.

Those are aquarelle (watercolor) inks for illustration, comics etc. Lucky me the magenta has the inflammable logo which means it's alcohol based but not ALL colors have the sign so I'm not sure they would all mix well with the resin.

first minute of mixing gave a chewing-gum pinky look to the mixture and I freaked out.

After one night of curing, the color was a nice signal red, still a little too magenta for me (but hey, that's what was written on the canister).

For my final attempt I decided to add also the crimson red glass paint to darken the color and it ended very well. I prepared more resin too, which helps for stirring and mixing.
Rule is hardener first, then resin. It cures over 24h, so no rush, take your time to mix, grab what's on the sides of the cup.
Added the color, mixed again, let sit for a while to have bubbles climbing up. The color with thicken the mixture, so leave the clear mix sit for a while to get rid of bubble, then mix the color, let sit again (10 minutes). Transfer the mix to another cup without shaking, that helps removing bubbles too and ensures you don't have any unmixed resin or hardener left in your new cup.

then use a 2D level to have your work on a perfectly horizontal plane. That resin is VERY THIN and will go everywhere (thanks for the warning, SD). You'd better have everything under (the clear styrene, if you remember) perfectly sealed. In any case, any hole / cavity will be filled up, so be prepared for the next 4-6 hours to monitor how it goes and refill when needed (I couldn't source glazing resin with 90 min curing time... and I don't feel like playing with additives yet)

testing the lights and the shade

So far so good. I had to make some resin again cause reaching the gel time took forever and the basement is barely at 19°C (not complaining but a bit low for resin curing). Gel time is like 4-6 hours. You need at least that time to make sure you won't have a window that will almost totally empty during the cure time.
You also need working lights to ensure you don't have a dirty color or mix.
Mine isn't perfect as it's not pure pigment but looks ok if you're at 20 cm of the prop.

The diffusion is AWESOME. Less crazy than on the pics but really diffused, you don't see a single spot but really a lit window.
I received my new carts. They are longer than the M84 ones that were supposed to act the same (I was told) and ended up not working most of the time.

*WAY* too short. Now I understand. The pin in the barrel isn't pushing the piston far enough and it's not maintaining the pressure between the piston and the firing pin.
Those new ones are reverse fed compared to the M84 and they will fire each time
I got some other sort of PFC caps that produces more sparks, it's awesome.

The new cart. fills up differently, and stores more pressure in the chamber so that blowback is spectacular and my beretta will slide-lock empty every time now !

Final stage

I'm really pleased how the dyed resin ended. Mixing isn't as perfect as with dedicated pigments (that I've bought in the meanwhile) but it's really nice and it diffuses the light very well.

? Full demo
In included a slow motion sequence, I'm impressed by the insane SPEED of that model gun mechanism (I was new to them). The blow-back feeling is of course less than on a real gun but it feels like the real thing, sparks, smoke :045:

Lawgiver MkII Final Demo - YouTube

Lawgiver MkII Mode Expert - YouTube

Thanks for reading and watching !

I started toying a bit with high speed photography and I figured a LG model gun would be nice to picture

here what I got during the lunch break (please excuse the mess of the white paper background, other experiment have been going on, and a few spills )

and part of the photo shoot,
here's The Anti-causal Matrix Oracle tomato (don't ask me, I don't how why or how...)

and the olympic diver tomato


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