[Bachelarius]

Hi guys, I have also posted this thread on Arnies, but would like to see if anyone here has any suggestions as well, as many of you seem fairly technically and mechanically minded.

I am being another foolhardy engineer and attempting to build an airsoft replica of the HK79. Not only that, I am trying to make a short version first, to fit my HK51, as well as most non-SD models of the MP5.

So far I have got it about 75% designed visuallyand about 90% designed mechanically, sourced most of the materials, and just need to finalise the designs before I get it all shipped in. Nicest thing is that I have now managed to cut it down to only 2 welds, and I think I will be able to make the entire thing screw together, if I play my cards right :)

http://www.hkpro.com/image/action2norway1.jpg


My tool of choice is the poor mans workshop, aka a dremel. What I need to know really, as far as designs go, is:

- What thickness of steel to use?

Can I get away with using 1mm steel for the upper frame for instance or is that going to flex like crazy?

Will I be able to cut through 2mm steel with the dremel?

- Also, is an inner diameter of 40mm too tight for a moscart shell to fit? I do have one to play with, but I don't want to waste money on incorrect parts...

- Oh, and how is a handguard attached on an mp5? Has anyone got any pics of how it clips on, other than the usual front pin? eg. what holds it on at the back? That could be a job for a second iteration though...

Next, does anyone have any pics other than the ones on hkpro? Something like a G3-TGS manual would be heavenly, but I just need as many details as I can get really, still trying to get my head around the shape of the damn thing, as I build it in solidworks... The fact that the site above has at least 3 different designs for the upper section does not help matters either...

Really, I am just after any input from anyone on this little project of mine.

[Mat]

Having done some research for the same project, ignoring the ones from HKPro, I've so far only managed to find these... one is cgi, but it does give you a nice view. Once you've made one, you can let me know how much for making another ;)


http://www.myvideo.d...ch/4001287/HK79
http://www.youtube.c...h?v=B-AdHrz_6Zo
http://i5.photobucket.com/albums/y163/Mat74/Mat%2079/127655_48.jpg
http://i5.photobucket.com/albums/y163/Mat74/Mat%2079/20050401_ag3hk79_render.jpg
http://i5.photobucket.com/albums/y163/Mat74/Mat%2079/79276.jpg
http://i5.photobucket.com/albums/y163/Mat74/Mat%2079/HKG41TSG.jpg
http://i5.photobucket.com/albums/y163/Mat74/Mat%2079/hk79g3.jpg
http://i5.photobucket.com/albums/y163/Mat74/Mat%2079/hk_79_grenade_01.jpg
http://i27.tinypic.com/eg9wep.jpg

[Mat]

Of course I'd prefer one the proper length ;)

[Bachelarius]

Many thanks Mat, I have no idea where you spotted those pics, but I definitely appreciate them. Will keep you posted on how it is going, but as I work ridiculous hours, it may will probably take some time to build. Also, I will not even dream of selling one until I am happy with it and have put it through at the very least a skirmish test.

As for the full length, proper version, it was something I was actually going to build side by side with the short one. Just need to get myself a full length g3 front end, so that I do not cock up the dimensions. Oddly enough, only 5 parts actually need to be changed to make the change from the short to a long, that is barrel and the two plates on each side. Trigger mech would be exactly the same length in both lengths.

Only thing I cannot promise in my design is the ability to cock the fire pin while on safety. I've racked my brain a lot over that one and just cannot see a way to do it without the use of custom, CNCed parts. But I will give it a lot more thought as I build and test that section.

BTW, I am fully aware of the fact that a short one does not exist in real steel. It's just something that does not make much sense to me, personally, but hey. I see the trade off of having a smaller grenade compatibility and range as a good one, in order to make the perfect short crowd control weapon. If it worked for the 203, it must work for one of these in real life, unless the catch is not strong enough? Who knows..

[Bachelarius]

One more thing to throw out there actually,

Has anyone got much experience with working with sheet metal? I have found a fantastic resource as far as working and shaping the stuff goes:

http://www.thebestca...read.php?t=2394 <- Slug Toys's posts seem to be very competant, detailed and helped me get my head around the tools I needed and the general process.

However what it doesn't talk about as such is the grades of mild steel sheet and in general, I just don't know which to use. Choices are: 0.9mm, 1mm, 1.5mm 2mm and 3mm. After taking a look at my computer cases, I have pretty much discounted 0.9mm, as that stuff is wafer thin, flexes like crazy and in general, will get a cheap feeling finish, as well as not giving me any room to filet the edges etc. Similarly, I saw my fiance's brother working with some, what looked like 2.5-3mm steel and that looked hefty enough to could kill a baby if it fell on one! So a dremel has absolutely no chance with that stuff. And I can vouch for that myself as I have been drilling a hole in my G3's sight for at least 4 hours in total, through different sessions, and I've STILL not finished it -_-

Anyway, anyone who has done any metal-work before, airsoft or on their cars or whatever, let me know how they got on, especially on small, fiddly bits. I've figgure out that the trigger alone will have anywhere between 5 and 8 90deg folds on it...


Cheers, Nikolay.
aka Bachelarius

This post has been edited by Bachelarius: 15 March 2010 - 02:09