I like lasers
For the record, the above laser is a British Armed Forces issue 5mw 535nm 500m Dot Laser. You normally
find them on the top of assault rifles. I do not own an assault rifle, or indeed a rifle of any kind. I do, however, own a bow. It turns out that bows and rifles don't have compatible sight mounts, for the obvious reason that a gun doesn't originate from the stone-age. The laser, it turns out, would not fit.
I'm not the kind of guy who takes "it won't fit" for an answer (insert whatever gross innuendo you wish there (no, THAT was not an innuendo for inserting something. Jezus christ guys, maturity much?)), so I set about making my own damn mount.
I used a vernier micrometer to measure up the connector on my bow, then set about making my own. The existing sight mount on the target bow has a rail which a sight attaches to and can slide backwards and forwards on to calibrate. The laser comes with it's own compensation and configuration circuits and adjusters, so a slider isn't required. You can see, above, that I've done away with the rail and just added in two M6 bolt holes, with a countersink on the inside so the mount self-centers to horizontal.
For anyone's reference, the bolts are M06, spaced at 0 degrees to the vertical, 32.5 apart with a 45 degree csink of depth 1 up to near enough 44.4 diameter. Bolt protrusion should be about 3-4. Units are metric.
Next up, I rendered it, dropping in a model of the hunting bow I made a few years ago. It's going on my target archery bow I use for competitions, so the objective here isn't to be camouflage or not to snag on stuff. It just needs to look sleek and intimidating. For this I took inspiration from the F-117 Stealth Bomber. Originally designed to never deflect radar back at the sender, the design is angular, sleek and modernistic, so perfect for intimidating a group of people using stone-age weapons. And of course it has to be black.On the left, the F-117 NightHawk. On the right, my 3D printed sight mount.
I chose black ABS, ordered from i.materialise in Belgium for a total of 20 quid, the majority of which was shipping so next time I'll get lots of parts before I get just one of them shipped over.
The hole in the center was made to be 25.2 diameter in order to have a .1 interference fit with the laser (which has a 25.4 diameter) so it'd be nice and snug and not move. I'd added the extra 0.1mm assuming that the 3D printer wouldn't be that accurate and I'd need material left over. It turns out that the printer was accurate to 0.01mm, and I had 0.1mm of excess to file away
See that slot down the middle? That's this mount's hidden weapon. In order for the laser to fit in, the hole has to be slightly larger than it's interference fit. It then needs to return to it's interference fit once it's attached to the bow. To do this, I added the slot down the middle, then spaced the mount holes 0.1 too close together, then on the model, stretched the hole vertically by 0.1mm. When the bolts are fitted to the sight and screwed in, the slot is made narrower, and the deformed circle becomes un-deformed, clamping the laser. If you're confused, picture trying to fit an AA battery into a party balloon. It won't help you picture the situation, but it'll be suitably bizarre that you won't ask me any questions for fear I say something worse
Pictures of the attached sight. In these two shots I'd messed up the calibration arrows so they were at 45 degrees to the actual calibration planes.
And here's what it looks like with the laser on
Most of this was done whilst my hand was kaput, so I've not had a chance to fire it yet. I've made a unit which only activates the laser once the bowman has pulled back to 90% of max draw, but fitting it is proving complex to do without it looking like s**t. Once I've done that, you'll get some shots of it in action.