V2 Mechbox Questions

[Flatlander]

Originally Posted by Danke

So why stop at 1? Why not 100 If it's that much of a bump them more folks would want one.

You might as well start with the best. Once you've got the copy up and running you can sell the mule and recover your funds.

Well atleast one of my teammates wants one also. If they're economically feasible and they turnout good I'd have more made for others who would want one. I'd probably have to sell a few to recoupe some of the startup costs.

I don't want to start with the "best" (G&P mechbox) as it cannot fit the modify gearsets which would be really nice for those less mechnically inclined. I also think the subframe holding the gears together will help with distributing the loads better, resulting in longer life span of components. Besides, from what I've heard all the "reinforcing" that goes into mechboxes isn't actually where they commonly fail - near the front of the cyclinder - so CNC'ing a reinforced mechbox is kind of useless.

[mcguyver]

I have a sneaking suspicion that this will not really be economically feasible, unless you are doing runs in the hundreds to keep the cost down. There have been guys in the U.S. who have done CNCd aluminum lowers for the PTW as an example, and they have been $500+ U.S., unfinished.

I forsee stainless steel to be much tougher to work with, as it's much harder than aluminum, and the costs would reflect this. It may be best to use an available mechbox, or abandon the plan as you will likely end up spending $1000 on mechbox and internals for an M4, when a PTW is only a few bucks more.

[Flatlander]

Originally Posted by kmsakura

this has happened before :P. if i remember correctly the cost was going to be around 500 per mechbox with the 3d scanning and machine paths done for free. never mind the fact that it had to be done on machine down time because prices would aproach 800+ if they were to machine a mechbox while running the machine under normal hours. i could be wrong though.

Prototype machining (ie. One-off custom) on a 4-axis machine here in Edmonton is around $100/hr and I think it was $80 for the cut path programming which needs to be done only once. I find it hard to see a mechbox requiring 8 hours of machine time. Mac says PTW lower receivers have been priced out to machine in the $500 range and I would imagine take longer than a small mechbox.

Anyways, no harm looking into it.

EDIT: Mac, I agree that machining SS will probably be pretty pricey due to its stregth but has a higher yeild strength than aluminum. However, steel has ductile to brittle temperature affects (ie. the colder it is the more brittle the material is - winter = bad on steel components) where as aluminum does not have this problem.

[bruce]

A few years back, I had a talk with one of my suppliers about machining some mechboxes. Even with me suppling the toolpaths for the CNC, he would only do a minimum of 100 pieces for around $300 a peice if I can remember correctly. That was with 6061T6 aluminum. Stainless steel would have been over $2000 a peice. All the parts would also be unfinished.

[Flatlander]

Bruce, do you remember how much chuck time each piece required? Or did he not say?

[bruce]

He just gave me a cost quote. I didn't ask for how long it'll take to machine each one. He would also be doing them when his machines are not running for some major contract.

[ThunderCactus]

Well you don't really need to improve on the design of the mechbox, just the materials it's made out of. You REALLY don't want to pay to machine stainless steel. What you want is a nice big solid chunk of chromoly steel, yep, that'll do it!
Infact, you could just as well get away with keeping the same crappy material they make gearboxes out of and simply add a radius where the gearbox shell always cracks at the front of the cylinder there. The reason it cracks is because its a 90 degree corner with no real structural strength. So in the end 7075 aluminum may be good enough for the job.

[ILLusion]

Or you could go with a regular reinforced gearbox (like a Systema) and throw in a silent head set.

That setup can take you up to 550fps and possibly beyond.

[Flatlander]

Originally Posted by ILLusion

Or you could go with a regular reinforced gearbox (like a Systema) and throw in a silent head set.

That setup can take you up to 550fps and possibly beyond.

Do the airbreaks on the systema silent head really work that well to reduce the impact? I haven't heard much about them reducing the impact dramatically but I have read that the sound reduction isn't noticably huge. I equated this with it not being a very effective airbreak. I may have to add one to the x-mas list...

[mcguyver]

Over-lube to the piston head of a silent head set will remove the effective braking. It clogs up the inlets on the head. When it's done correctly, it does work.

[ILLusion]

Originally Posted by Flatlander

Do the airbreaks on the systema silent head really work that well to reduce the impact? I haven't heard much about them reducing the impact dramatically but I have read that the sound reduction isn't noticably huge. I equated this with it not being a very effective airbreak. I may have to add one to the x-mas list...

It's not an airbrake. The part does the job through softer materials combined with unique shaping to spread the impact over a greater area of the cylinder head/piston head.

Vibrational tests* done by our MadMax have proven that the Systema silent head set is miles ahead of any synthetic "flat" piston head.

But if you want the ultimate in impact reduction, the Angel Silent Headset more than DOUBLED the amount of impact that was reduced when compared to the Systema solution. It's also an actual "silent" head set in that it will actually reduce the perceived sound of impact.



* I was present for the testing of the silent head sets, but the results were never published. They were performed for a project that MadMax was working on that never panned out since the existing solutions all proved to be much more effective than currently known air braking solutions.

[Nova316]

I thought systema silent heads were impressive, I guess ill try angels next time. I have upgraded a TM gearbox with highspeed helical gears shooting at 400fps with an insane rate of fire, he blows through 1/2 a box mag a game, and its been an entire season without the gearbox breaking or even signs of cracking. I could only imagine how well an Angel set would last

[TokyoSeven]

and then there are jerks who have the aluminum piston heads...

[ThunderCactus]

HEY! I have an aluminum piston head in 2 guns! lol