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Everything posted by Hangtight

  1. VFC & G&P receivers are nice. Everything else can be changed so 'nice' depends on how much money you want to spend. But as a rule the rail, stock etc that higher end guns come fitted with are generally very good. Asking which M4 has the 'best' externals is a bit like asking, "Which car looks best...". You need to decide what 'best' means before it has any significance.
  2. Use shims on the rear of the gearbox to prevent the front of the gearbox tipping up as you tighten the buffer tube screw. If you remove the barrel and hop then look down the outer barrel with the bolt cover open, you should see the air nozzle exactly central with the outer barrel. Find an O ring that fits over the barrel and push it right up to the hop up. Use a razor blade to cut it to about half thickness. This will push the hop against the gearbox. It might take a couple of attempts to get just right, but it's much better than the little spring that's supposed to do the job. If your gearbox is 'reinforced' with the pointless lump of metal around the spur gear you won't be able to fit low ratio gears. But this is nothing that can't be fixed in five minutes with a Dremel.
  3. If you're using pre cocking then the BB is on its way as soon as you pull the trigger, after which the gearbox will cycle and pull the piston back for the next shot. On 7.4v, 16TPA motor and stock gears the gearbox will still cycle faster than you can pull the trigger, but it'll sound and feel better with the 12:1 gears. Pre cocking shouldn't increase the wear on any components as long as they aren't overstressed, as all the gun is doing is supporting a static load until the next time you pull the trigger. With the Titan you turn the pre cocking on and off via a trigger pull and moving the selector, so it's easy to turn it off at breaks or the end of the day and fire a shot to release the spring tension for storage.
  4. Absolutely. 16TPA and 12:1 will pull a 120 no problem, as long as the battery can supply the current. If it's well shimmed it should be around 20A continuous, but start up current could be as high as 80A. That why motors get hotter if you're shooting a lot of semi auto as you're starting the motor from stationary with every shot.
  5. With standard gears you'll still be hitting 40rps, but the M120 spring together with losing a bit of weight out of the piston (take the bearing out and replace with a lightweight plastic spacer) should see you the right side of pre engagement. The M120 will put you at around 400fps though, but you can bring the FPS down by short stroking the piston. This involves removing teeth off the pickup side of the sector gear so it doesn't pull the piston back as far. Three teeth should bring you back down to about 350fps. It'll still be inefficient firing semi auto though, and I suspect the motor will get uncomfortably hot after only a moderate number of shots. The Titan is designed for lipo, and from memory the number of buzzes when you plug the battery in is it telling you how many battery cells it thinks are detected. If you plug in a 9.6v NiMh the Titan will think it's seeing an 11.1v lipo, but if the voltage is below the cut off threshold it won't fire as it's designed to protect lipos from over discharging.
  6. On an M100 spring the maximum ROF you can achieve with a full piston stroke is around 30rps. Beyond that the piston doesn't have time to complete it's stroke before the sector gear comes around again for its next cycle. That's pre engagement and it destroys pistons and smashes teeth off gears. With that motor you'd need to go back to the standard gears and run 7.4v which would give 25rps,but if you're intending to use mainly semi auto that'll heat up the motor really quick. If you want good semi auto performance then go with my suggestion of 16TPA balanced motor on 7.4v, the 12:1 gears, your M100 spring and have the pre cocking turned on in the Titan. I run that set up but with 13:1 gears in a couple of my guns and it rocks as well as being reliable.
  7. That combination of motor, gearing and battery are going to try and do almost 60 rounds a second. On an M100 spring you'll hit pre engagement at about 30rps. On that gearing a 16TPA balanced motor (30k) and 7.4v lipo will get you a solid 25 rps with no danger of pre engagement on that spring. That'll also get great trigger response, but to get instant trigger response you use the pre cocking function on the Titan.
  8. Don't do what's not necessary. Although it's possible to lighten a piston and retain the strength required to do the job, it's only really needed for more extreme rates of fire. In fact a lighter piston is bad for efficiency, so you want the heaviest piston that's consistent with the cycle speed. A typical DSG has enough cylinder compression to support a barrel about 200mm long. If the barrel is any longer then there is no air pressure to continue pushing the BB and it then becomes a piston in the bore with potentially negative pressure behind it actively slowing it down. With no air pressure to provide the air 'cushion' around the BB it will also be more influenced by the bore quality which might have an effect on accuracy. SHS have recently had some quality control issues, which is why I suggested the ZCI 16TPA motor. If you feel like spending a bit more then the new ASG Boost 30k is excellent.
  9. On 11.1v 22TPA will give you 40+rps (ZCI Torque $30), or 16TPA will give you 45+rps (ZCI balanced $30). At those speeds there should be no reason to lighten the piston any more than taking the bearing out and replacing it with a light plastic spacer.
  10. Make sure you understand about the function of the barrel crown before you cut the barrel.
  11. It gets wider with experience! But the margins for error get a lot narrower as rps goes up, the same as trying to extract the maximum performance out of anything.
  12. 45rps and 330-340fps is completely doable without costing much. Mine is built out of bits left over from other guns and a SHS DSG and is reliable and fun.
  13. Go for 200mm as that will work well with the swept cylinder volume you'll achieve with a DSG. Anything longer and you're just not going to be able to move enough air.
  14. Mechanically that's not much difference between SSG and DSG, but once the sector gear starts spinning much faster than 30 revolutions per second then the margins between the time it takes for the piston to complete its stroke, the gearbox to cycle, between a component being strong /light enough becomes almost non existent in some cases and it becomes a juggling act between speed, spring, stroke, weight and strength. A 40rps DSG isn't really much more stressed than a 25rps SSG in some respects, but a 45 rps SSG is walking a fine line between success and failure. If you want to get close to that line then you have to kind if sneak up on it, know when you've crossed it and then go back a step.
  15. That'll teach me to try and read tables at 6 in the morning without my glasses on... Still, 50rps on a 120(ish) spring with only a 2 tooth short stroke is impressive. The piston must be almost non existent!
  16. You could do a 13:1 DSG build but only if you use a 22TPA motor which will get you around 55rps on 11.1v. If you want to use your existing motor, then stock 18.72:1 gearing will also get around 55rps on 11.1v, but for the sake of anyone on the receiving end and your internals you'll probably want to keep that to under 1J (328fps). Slightly more sensible is stock G&P gears (tough 9 teeth primary spur on the bevel) which give 20.2:1 gearing, which with a 35k motor and 11.1v should manage a solid 50rps. Probably still keep it to 1J, but with a careful build that has a chance of holding together OK using inexpensive parts. But you'll need to make the most of the cylinder volume that it'll have, so a 200mm barrel will be a lot better than the 110mm, otherwise you'll need the sort of spring that's more likely to break a V2 gearbox to get any fps.
  17. He's using a Guarder SP110 spring, which is equivalent to an M130, perhaps a bit higher. 13:1 gears are actually 13.66:1. I'd imagine the G&P piston he's using is mostly air (he states it's Swissed in the description) and I'd also reckon on it not lasting that long. His gun is probably pushing 400fps but you said you wanted 350,hence the more severe short stroke. That description only hints at the amount of work and experience that went into making that gun hold together. But you carry on, because how hard can it be? Given that 50rps SSG builds are pretty thin on the ground, I'm still going with 'harder than you think'.
  18. 35k motor on 11.1v, 13:1 gears is heading for 40rps, so M130 spring, light piston and 4-5 tooth short stroke if you're trying to get 350fps (probably 4 with the really short barrel, but you'll get better efficiency and accuracy with 180-200mm), but you'll still be pushing your luck a bit. A DSG that does slightly higher rps and 340fps would be less highly stressed and probably more reliable... Just because it doesn't look hard, doesn't mean that it's easy. I'm an engineer by training and I've got a collection of broken parts that'll back me up on this one! Having a gun that does 40-50rps isn't much used if it only lasts ten minutes every time you take it to a skirmish, even if you have a back up.
  19. That was supposed to read 'use'... Bloody Swype keyboard thing!
  20. You said you wanted to do a DSG for under $100 ZCI 16TPA motor $30, SHS DSG sector $15, M150 spring $15, SHS lightened full rack piston $12, basic Mosfet $15. You use your stock 18:1 gears, port the existing cylinder and find a stock 230mm barrel from somewhere. You could use the titan motor, but it might struggle a bit, but if the battery and wiring can supply the current then it'll push the set up above at getting on for 50rps. And don't expect to get it right straight away. When you start stressing components like this, things break. If you've never done a DSG before then start small and work up, and don't use your only gun!
  21. Some gearsets and gearbox shells just not compatible. Look for a gear set with a thinner bevel gear. Last one I had an issue with was JG gears into a SRC shell. It just wouldn't go.
  22. Is not the motor burning out that's going to be the problem. Pre engagement is going to be an issue though.
  23. Junk flash mags are terrible, but I'm happy with the Lonex ones. I've got a couple of full delivery hi caps, but it's good to know which ones actually have the full spring in. Even better are the ones with a full spring and the Allen socket winder in the side. With the stroke available off an 8 tooth DSG, 230mm gives about the right cylinder/barrel ratio. Once you get under about 200mm you need to start thinking about heavier springs to accelerate the BB. My CQB gun has a 170mm barrel and needs a M110 spring to make 340fps when M100 in a 230mm barrel does 335fps.
  24. That would be a nice build with a 16TPA motor and 7.4v lipo, but it'll just destroy itself with 11.1v,and especially with the 35k motor. 40+ rps and 320fps is easy with a simple DSG, and reliable. SHS HT motor, stock G&P gears (20.2:1, tough), SHS full rack piston, already lightened enough of you leave the bearing out, SHS 8 tooth DSG, M150 spring, Cheap Firestorm basic Mosfet and a 2550mah 30/60C 11.1v lipo. Add a couple of flash mags to keep up with the ROF, or a 900 round mega mag and you're golden. You've got enough cylinder volume for a 230mm barrel and 0.25g BBs.
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