Tavor MARS sight project

extremetaz

Right - so I got my Tavor

and I'm delighted with it - it's a crackin' piece of kit so far.

having said that, I'd already junked the MARS sight before I'd even fired a single shot from it. Thankfully, the iron sights, once set are pretty decent.

However, I do like the look of the MARS unit and so split it open to see what I could do about the dot clarity and the lasers tendency to drift (LOTS!!)

The opening of the housing was an ordeal in itself - I had to drill the heads of two of the four allen bolts on the bottom, and then both of the heads of the two holding in the switch contact plate in place.

The four bolts in the housing were all mis-threaded - looks like the wrong thread pitch used for the taps in place. Easy to fix but should never have happened. The latter two bolts were threaded fine but the heads off all of the bolts are either imperial or just a smidge over 1.5mm (badly made, ie: cheap) as the 1.5mm allen couldn't grip them, but the 2mm allen was WAYYY too big.

Anyways - got the case opened for a looksie.


First, the laser - them amount of free play in the adjustment mechanism is rediculous! The adjusting screws themselves work fine - however they aren't direct acting (if they were, there'd be no problem) and the linkages are utter rubbish. Not much can be done about that without reshaping the linkages, or coming up with a better linkage (which might actually be doable as I look at it... )

For the moment however, forget about it.


Now - the main event - that horribly nasty blurry aweful excuse for a red "dot" (more like a red smudge sight!)

I removed the carrier (finally found two bolts that did what they were supposed to do) for the spot generator.

I've never opened up a red dot before and was expecting to find a very small laser diode, or at least a sub-miniature surface mount led with some sort of focusing lense.

What I found... was a bog stock 3mm red led with a pinhole grating in front of it. Which explains why the spot is so poorly defined. The hole in the grating is absolutely tiny and is most likely causing some diffraction.

So - to the point - has anyone got an old, damaged or beyond use red dot lying around that I could salvage a decent dot generator out of? I'm thinking maybe one of those el-cheapo holosights that's suffered a BB strike or similar?

Shall keep ye posted anyways.

TheDoc

I've got two damage Eotechs ( if you want to get fancy)

I've also got a red dot scope with no battery you can have.

And i also have **** loads of lasers if they are any use.

evilrobotshane

I've got a little Doctor style sight or something like that you may have.

Stercus Accidit

Fair play if ye fix it.


If its the ARES I advice dumping the lens and all, the parallax is not self correcting.

Imagine if you had a piece of glass, and drew on a dot, it moves all over the place when you move your eye, thats what they have, there was a youtube video showing it clearly.

If they fixed that great, but be aware that if you fix the other issues, it could wind up being totaly useless anyway.

Keep us posted anyway, sounds like a worthwhile fix.

extremetaz

TheDoc wrote: »

I've got two damage Eotechs ( if you want to get fancy)

I've also got a red dot scope with no battery you can have.

And i also have **** loads of lasers if they are any use.

Will take you up on that dude - if you're coming to HRTA wednesday, bring what ever you're happy to spare and I'll see what I can do with it.

Eotech reticle in the MARS would look crackin' - but I'll see what I can do about fixing them before I go using them for parts on ya.

@Stercus - That would require an appropriately tapered lense to correct yes?

Both "lenses" in the MARS are indeed simply flat plates, so fixing this would involve finding a suitable donor part for the front lense. That could be a problem alright.

Stercus Accidit

I'd recommend using as much of the guts of those eotechs you are being offered, including dremmeling the shape of the edge of the lens to fit, a bit tedious and quite a challenge I'm sure but probably needed.

Maybe there is a red-dot type with a similarly shaped lens?

extremetaz

Stercus Accidit wrote: »

including dremmeling the shape of the edge of the lens to fit...

...Maybe there is a red-dot type with a similarly shaped lens?

I had thought of that alright - concern though is that the front lense is slanted in the MARS so this may not be sufficient. Having said that - it'll probably still be better than nothing so I'll definitely look into it.

extremetaz

Right - I found a few minutes to dig the rest of the way into the MARS sight there during the week.

The news is not good.

The laser pointer is mounted on a single pivoting point at the back end of it's housing.

The linkages are between the pivot point and the back of the laser housing.

The linkages do what they should but there's too much play and as a result, any sort of a shake will throw the laser out of alignment by a potentially massive amount.

For this system to work - the pivot would have to be MUCH stiffer and I don't think that the linkages would be able to move it if that was the case.

The clearances in the linkages appear to be necessary for the whole lot not to simply jam up so I also don't think that reworking them is going to make any difference.

Bottom line - the laser pointer module is a complete lemon - unsalvagable - forget about it. Your best bet would be to line the module up roughly with the ironsights and fix it in place by filling the cavity with silicon gel or similar.

Otherwise, just mount a standard laser and wire it to the built in switch(if you're really that bothered about having a laser in the first place).


The sight itself then is also pretty much a total loss.

I bought one of those cheap EOtech's on ebay (the ones that don't have enough vertical adjustment and are invariably too high) and had a look inside it. The dot generater in it is the same type as used in the MARS sight (3mm LED behind reticle grating) except that the carrier is slightly different - I'm pretty sure that it wouldn't take much to either adapt the EOtech carrier to the MARS type or to reset the grating and LED from the EOtech into the MARS carrier. The thing is, I don't know how much point there is in doing this as, although it's nowhere near as bad as the MARS, there is still some fuzziness to the reticle in this particular brand of EOtech too.

I had a good look at the lenses in the EOtech - and as Stercus suggested, they are shaped to be parallax correcting whereas the lenses in the MARS are simply flat glass.

There is probably just about enough glass in the EOtech lenses to allow them to be cut to fit the MARS but I haven't compared them side by side as the EOtech lenses appear to be impossible to remove without first removing all the circuitry - and frankly, I haven't been bothered to date.

Furthermore, the EOtech lenses are designed to be used aligned vertically, whereas the front lense in the MARS is sloped, so I've no idea what implications that has either.

I might come back to this again in a few weeks but I've other stuff to play with between now and then so don't expect anything.

Stonewolf

surely you could mount the EOtech lenses in the mars sight and put a simple bit of flat glass at a slant on the front.

Inari

Stonewolf wrote: »

surely you could mount the EOtech lenses in the mars sight and put a simple bit of flat glass at a slant on the front.

Agreed. You could even put in a stronger material that will protect your ultimate sight from the rare BB-through-the-optics shot

extremetaz

Stonewolf wrote: »

surely you could mount the EOtech lenses in the mars sight and put a simple bit of flat glass at a slant on the front.

The space isn't there to do it unfortunately. That arrangement would have the two lenses 20mm apart in the best case scenario - and it involves building an additional holder inside the MARS unit to hold the EOtech lense vertical.

To be honest, given the amount of work this is looking like it would entail, coupled with the fact that TSI are due to be bringing out their own MARS around the $100 price mark, I reckon I'm gonna shelve any farther efforts on this until I see how the reviews for the TSI unit compare.

Masada

extremetaz wrote: »

To be honest, given the amount of work this is looking like it would entail, coupled with the fact that TSI are due to be bringing out their own MARS around the $100 price mark, I reckon I'm gonna shelve any farther efforts on this until I see how the reviews for the TSI unit compare.

Except, If its scaled (and indeed, even going to happen) for the TSi Tavor then its going to look humongous on an Ares Tavor,.:)

Puding

have to agree with masada hear, the tsi tavor was shocking, i do not hold out much hope for the mars at the moment

extremetaz

That is a fair point - nevertheless - I'll wait and see.