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F1ERRI

Feedback on custom AK gearbox build

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Hello,

 

As I am a fairly inexperienced at airsoft teching, I wanted to get some feedback on my upcoming Ver.3 gearbox build.

Any input from expierienced tech's would be greatly appreciated.

I will use this setup with 7,4V Li-Po's.

 

Here are the parts:

  • Energy X-Power 8mm Bearing Gearbox Ver.3
  • Big Dragon M160 High Speed & High Torque

  • Military Action Motor Frame for AK

  • SHS Torque Up High Speed Flat Gear Set 18:1

  • SHS 8mm Steel Ball Bearings

  • Gate NanoSSR MOSFET

  • SHS Spring M130

  • Element Spring Guide Ver.3

  • SHS Stainless Cylinder Horizotal Thread (Type-V)

  • Element Aluminum Cylinder Head Ver.3

  • SHS Tappet Plate Ver.3

  • Military Action Aluminum14 Teeth Piston

  • Military Action 8 Holes Piston Head

  • Commander Shim Set

  • SHS Heat Resistance Switch Ver.3

Ruhjuif.jpg

Thank you in advance!

Edited by F1ERRI

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A few things I'd do differently, and the reasons why.

Solid bushes rather than bearings, or at least a solid bush on the thrust side of the bevel gear and both sides of the sector gear. At the sort of ROF you seem to be aiming for bearings will make little to no difference. They are somewhat less suited to the types of loads found in an Airsoft gearbox and are prone to catastrophic failure if not very accurately shimmed. They are also less suited to side loads, ie on the back side of the bevel gear.

A steel spring guide rather than the aluminium one. A hard steel spring on a soft aluminium guide... It'll gall the surface and start to generate friction.

SHS springs are OK but can be variable. I like Modify for their excellent consistency. And remember if it's a variable pitch spring put the more closely spaced coils to the rear of the box over the spring guide.

There are now better motors available than this. I'm sure someone with direct experience will be along to suggest an superior alternative.

You don't mention a nozzle a go with the cylinder head, but stick with the same manufacturer in the hope that they'll be correctly sized to work together.

Go for a lighter plastic piston with a half metal rack. At the 20ish rps you'll possibly achieve you'll want to keep the piston weight down to keep away from any pre engagement issues. Keep the combined weight of the piston and piston head to below 25g and you should be OK. I successfully use SHS 7 tooth (half rack) with a aluminium or plastic piston head at 20rps with no issues. Lonex red is also a good choice.

Don't forget Deans connectors and decent 16awg wire. I believe the Gate SSR has a built in thermal fuse for protection, but I use the Fire Storm basic Mosfet because its half the size and half the price, comes with decent wire already soldered to the unit and also has a built in

Thermal fuse. The SSR has Deans connectors at either end which makes the unit bulkier, and the trigger connection can have a habit of coming loose without measures taken to secure it. It works fine though if you can't get the Firm Storm.

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If this is your first and only AEG. This upgrade project is far to ambitious.

 

Way to many varying parts that will confuse you to no end when your AEG does not turn over when you snap it together. Anything over M120 you should be using SOLID bushings.

 

Full Rack pistons are weak if not prepped correctly and not ideal.

 

Motor is a rebrand ZCI unit...its a scalp the newbie item. And isn't worth the $40.00 price point that they sell for. Big Dragon is not know for any quality in their items.

 

1/4 of the parts you listed as a replacement is not even an upgrade. Type 5 Cylinder? Never heard of such creature, what wrong with your cylinder? It's 0, 1, 2, 3

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If this is your first and only AEG. This upgrade project is far to ambitious.

 

Way to many varying parts that will confuse you to no end when your AEG does not turn over when you snap it together. Anything over M120 you should be using SOLID bushings.

 

Full Rack pistons are weak if not prepped correctly and not ideal.

 

Motor is a rebrand ZCI unit...its a scalp the newbie item. And isn't worth the $40.00 price point that they sell for. Big Dragon is not know for any quality in their items.

 

1/4 of the parts you listed as a replacement is not even an upgrade. Type 5 Cylinder? Never heard of such creature, what wrong with your cylinder? It's 0, 1, 2, 3

What about the SHS High Torque motor?

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A few things I'd do differently, and the reasons why.

Solid bushes rather than bearings, or at least a solid bush on the thrust side of the bevel gear and both sides of the sector gear. At the sort of ROF you seem to be aiming for bearings will make little to no difference. They are somewhat less suited to the types of loads found in an Airsoft gearbox and are prone to catastrophic failure if not very accurately shimmed. They are also less suited to side loads, ie on the back side of the bevel gear.

A steel spring guide rather than the aluminium one. A hard steel spring on a soft aluminium guide... It'll gall the surface and start to generate friction.

SHS springs are OK but can be variable. I like Modify for their excellent consistency. And remember if it's a variable pitch spring put the more closely spaced coils to the rear of the box over the spring guide.

There are now better motors available than this. I'm sure someone with direct experience will be along to suggest an superior alternative.

You don't mention a nozzle a go with the cylinder head, but stick with the same manufacturer in the hope that they'll be correctly sized to work together.

Go for a lighter plastic piston with a half metal rack. At the 20ish rps you'll possibly achieve you'll want to keep the piston weight down to keep away from any pre engagement issues. Keep the combined weight of the piston and piston head to below 25g and you should be OK. I successfully use SHS 7 tooth (half rack) with a aluminium or plastic piston head at 20rps with no issues. Lonex red is also a good choice.

Don't forget Deans connectors and decent 16awg wire. I believe the Gate SSR has a built in thermal fuse for protection, but I use the Fire Storm basic Mosfet because its half the size and half the price, comes with decent wire already soldered to the unit and also has a built in

Thermal fuse. The SSR has Deans connectors at either end which makes the unit bulkier, and the trigger connection can have a habit of coming loose without measures taken to secure it. It works fine though if you can't get the Firm Storm.

Thanks for the feedback, greatly appreciated!

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The SHS Hi torque paired with 13:1 gears would be an OK choice and one I've used successful. A better choice would be one of the new generation of high torque /high speed motors with the 18:1 gears.

Don't expect to just be able to assemble these parts and have it work straight away. With components from so many different sources there WILL be fitment issues. Nothing that can't be overcome but you need the experience and tool skills to identify and rectify any potential difficulties before you pull the trigger for the first time and wreck a bunch of parts.

I take it you're trying to build a complete gearbox from parts, as your list is only missing an anti reversal latch and the springs, but the fact they're missing perhaps indicates the you've not had a gearbox apart before? If that's the case, get a boneyard gun and learn on that. The gearbox shell you listed will likely do the job but it'll need some preparation. Learn how to use a Dremel to radius corners on a junk shell rather than your brand new one. Try and put the parts together from different guns and learn what works, what doesn't and how to correct the issues. I'm not trying to put you off, but just don't want to see you make an expensive mistake.

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The SHS Hi torque paired with 13:1 gears would be an OK choice and one I've used successful. A better choice would be one of the new generation of high torque /high speed motors with the 18:1 gears.

Don't expect to just be able to assemble these parts and have it work straight away. With components from so many different sources there WILL be fitment issues. Nothing that can't be overcome but you need the experience and tool skills to identify and rectify any potential difficulties before you pull the trigger for the first time and wreck a bunch of parts.

I take it you're trying to build a complete gearbox from parts, as your list is only missing an anti reversal latch and the springs, but the fact they're missing perhaps indicates the you've not had a gearbox apart before? If that's the case, get a boneyard gun and learn on that. The gearbox shell you listed will likely do the job but it'll need some preparation. Learn how to use a Dremel to radius corners on a junk shell rather than your brand new one. Try and put the parts together from different guns and learn what works, what doesn't and how to correct the issues. I'm not trying to put you off, but just don't want to see you make an expensive mistake.

Thanks, I have had quite an expierience with V3's - stripped two gearsets, butchered a motor, broken a gearbox shell, broken a cylinder head etc. I feel very confidient of making this build happen, but I have never radiused a GB, whats the best way to approach it?

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Either a straight sided 3mm diameter bit in the Dremel, or a small round section needle file. If you've not done it before then I'd suggest going slow with the needle file. The object is to remove just enough metal in the front four corners of the gearbox shell to eliminate any sharp internal corners and edges. But with a file if you just saw backwards and forward across the corners you're effectively making dozens of little sharp corners as the file marks will be going across the corner. The trick is that once youve got the shape right to polish your work with, say 600 paper so all the polishing marks flow around the corner.

Don't try and get the gearbox together in one go. Fit the piston, put a few screws in and check the shell closes down properly and the piston moves freely. Do the same for every component, and then start putting them together in groups, eg cylinder and cylinder head, then with the piston and piston head, then with the tappet plate and nozzle etc. Take it slow and check the function at every stage.

Shim the gears by starting with the motor height, then the bevel gear followed by the spur then the sector. Don't try and take short cuts. Gently torque down the gear case screws for each gear as you adjust the shimming. Follow some of the excellent videos available.

Don't forget to adjust the AOE. Don't bother with Sorbo pads, shower hose washers and thin and cheap and can be stacked to get exactly the right thickness. Use rubber cement to glue them into place on the cylinder head. Super glue is quick, but it fails. Again, watch videos.

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Either a straight sided 3mm diameter bit in the Dremel, or a small round section needle file. If you've not done it before then I'd suggest going slow with the needle file. The object is to remove just enough metal in the front four corners of the gearbox shell to eliminate any sharp internal corners and edges. But with a file if you just saw backwards and forward across the corners you're effectively making dozens of little sharp corners as the file marks will be going across the corner. The trick is that once youve got the shape right to polish your work with, say 600 paper so all the polishing marks flow around the corner.

Don't try and get the gearbox together in one go. Fit the piston, put a few screws in and check the shell closes down properly and the piston moves freely. Do the same for every component, and then start putting them together in groups, eg cylinder and cylinder head, then with the piston and piston head, then with the tappet plate and nozzle etc. Take it slow and check the function at every stage.

Shim the gears by starting with the motor height, then the bevel gear followed by the spur then the sector. Don't try and take short cuts. Gently torque down the gear case screws for each gear as you adjust the shimming. Follow some of the excellent videos available.

Don't forget to adjust the AOE. Don't bother with Sorbo pads, shower hose washers and thin and cheap and can be stacked to get exactly the right thickness. Use rubber cement to glue them into place on the cylinder head. Super glue is quick, but it fails. Again, watch videos.

Thank you so much for the feedback, hopefully, when I get the parts everything will go fine.

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I guess I'll come out of my hiatus and chime in on this. Firstly, what's the base gun? You can probably keep several of the stock parts, including the stock gearbox shell. The motor will be fine, it's not the best motor out there, but it should get the job done. I'd replace all Element and Military action parts with SHS, I agree with the guys above, fewer brands give less fitment issues. Aluminum pistons are pointless for 99% of setups, I'd only use one in an extremely high power setup, an SHS 15T with a glued teeth rack and corrected AOE will easily handle an M130, I know this from experience. I'd also go with a nylon or pom piston head, it'll be more gentle with the cylinder and gearbox shell. Either get high quality ball bearings or use bushings, I wouldn't trust SHS bearings, I primarily use G&P bearings myself, but anything below 8mm and I use solid steel bushings. The gears are fine and should hold up for several years if you shim them properly, I'd use a lower ratio with a higher TPA motor, but that's just how I do things.

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... fewer brands give less fitment issues. Aluminum pistons are pointless for 99% of setups, I'd only use one in an extremely high power setup, an SHS 15T with a glued teeth rack and corrected AOE will easily handle an M130, I know this from...

That is this piston BTW...and not just "any" SHS piston.

 

51W7voMPczL._SX450_.jpg

Edited by Guges Mk3

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I guess I'll come out of my hiatus and chime in on this. Firstly, what's the base gun? You can probably keep several of the stock parts, including the stock gearbox shell. The motor will be fine, it's not the best motor out there, but it should get the job done. I'd replace all Element and Military action parts with SHS, I agree with the guys above, fewer brands give less fitment issues. Aluminum pistons are pointless for 99% of setups, I'd only use one in an extremely high power setup, an SHS 15T with a glued teeth rack and corrected AOE will easily handle an M130, I know this from experience. I'd also go with a nylon or pom piston head, it'll be more gentle with the cylinder and gearbox shell. Either get high quality ball bearings or use bushings, I wouldn't trust SHS bearings, I primarily use G&P bearings myself, but anything below 8mm and I use solid steel bushings. The gears are fine and should hold up for several years if you shim them properly, I'd use a lower ratio with a higher TPA motor, but that's just how I do things.

Base gun is a CYMA 040 (basically an Beta Project AK)

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Full metal rack piston with an extensive 'Swiss cheese' lightening job and a nylon cylinder head is 24.5g. An SHS half rack piston,standard with an aluminium head is... 24.5g. They're going to hit the cylinder head with the same force. The key to avoiding piston slam is getting the cylinder volume correct for the barrel length and ammo weight. A half rack piston should be fine for a M130 spring, is easier to make a neat job of trimming the first and second (or second and third if you're counting the stop at the back as a tooth) and gives a 'soft' point of failure if things go badly wrong. Use a full metal rack piston if you feel it gives you peace of mind, but be aware that there can be issues associated with it that need to be considered.

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24.5 grams? try 17 grams with only AOE correction, 15 grams with half the the teeth removed for DSG use, that's significantly lighter than 24.5 grams. This piston is still durable enough to withstand a 50rps DSG setup with an M170 spring, so it'll easily handle a 20-30rps SSG setup with an M130 spring.

IMG_20160501_225447_zpseqjzpf11.jpg

 

The lessened impact from a plastic piston head compared to a metal piston head might be negligible, but it'll be gentler on the cylinder anyway. If the base gun is a CYMA CM.040 chances are that it has a 28TPA motor with neodymium magnets, it'll pull pretty much any load with a strong battery.

 

I see your point of having the plastic teeth as a controlled failure point. I probably does things quite differently than you guys, I don't bother with mechanical failure points anymore, I just go for maximum durability and wear resistance.

Edited by Lefse

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You have to realize...many kids in the US think upgrades are like video game guns upgrades. Just drop the parts in...

 

On top of that they don't have the right tools to do the job...

 

Your an artiste with what you did to that piston. I wonder if I can carve our a Super Core Piston like that?

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18.5 g with the spacer /bearing removed and replaced with a plastic spacer, so we're not far off! Thing is, that amount of work is wasted on what the OP seems to be trying to achieve based on the parts he's posted. Horses for courses. If you want snappy trigger response, 20rps, durable and runs like a champ then it can be done with off the shelf parts and some careful matching /assembly. And there's more than one way to skin a cat.

I tend to steer clear of high stress builds partly because I reached a point where I'd rather be out using my toy guns rather than squeezing performance of of them, and also because I found a level of performance that I like. 20rps is plenty for me and I can build a few different ways that get great trigger response and last without bits failing. Getting half way through a skirmish and having something go wrong with your gun sucks.

So, to the OP, perhaps let us know what it is you're trying to achieve with this and we can present you with sensible options and advice and help you select the best parts for function and value to get you where you want to go and keep you there. ;)

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18.5 g with the spacer /bearing removed and replaced with a plastic spacer, so we're not far off! Thing is, that amount of work is wasted on what the OP seems to be trying to achieve based on the parts he's posted. Horses for courses. If you want snappy trigger response, 20rps, durable and runs like a champ then it can be done with off the shelf parts and some careful matching /assembly. And there's more than one way to skin a cat.

I tend to steer clear of high stress builds partly because I reached a point where I'd rather be out using my toy guns rather than squeezing performance of of them, and also because I found a level of performance that I like. 20rps is plenty for me and I can build a few different ways that get great trigger response and last without bits failing. Getting half way through a skirmish and having something go wrong with your gun sucks.

So, to the OP, perhaps let us know what it is you're trying to achieve with this and we can present you with sensible options and advice and help you select the best parts for function and value to get you where you want to go and keep you there. ;)

I mainly want to achieve consistency, reliability, crispy trigger response (as I am mostly firing semi), really do not care much about RPS (20rps is fine)

Also, would I encounter any PME, I suppose not, but just in case...

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You have to realize...many kids in the US think upgrades are like video game guns upgrades. Just drop the parts in...

 

On top of that they don't have the right tools to do the job...

 

Your an artiste with what you did to that piston. I wonder if I can carve our a Super Core Piston like that?

The thing is, I'm considered a highly skilled tech, I don't mean to brag, the point is that most of my skill comes from trial and error. IMO a good tech has the guts to push limits and is not afraid to fail. I too had their attitude several years ago, I bought a Deep Fire M120 tune-up kit and was confused when I just got 300fps out of it and it wasn't reliable at all. I'm sure all the "big names" in the airsoft community started out this way.

A Super Core piston with a weight reduction like that would probably be an excellent high speed piston.

 

18.5 g with the spacer /bearing removed and replaced with a plastic spacer, so we're not far off! Thing is, that amount of work is wasted on what the OP seems to be trying to achieve based on the parts he's posted. Horses for courses. If you want snappy trigger response, 20rps, durable and runs like a champ then it can be done with off the shelf parts and some careful matching /assembly. And there's more than one way to skin a cat.

I tend to steer clear of high stress builds partly because I reached a point where I'd rather be out using my toy guns rather than squeezing performance of of them, and also because I found a level of performance that I like. 20rps is plenty for me and I can build a few different ways that get great trigger response and last without bits failing. Getting half way through a skirmish and having something go wrong with your gun sucks.

So, to the OP, perhaps let us know what it is you're trying to achieve with this and we can present you with sensible options and advice and help you select the best parts for function and value to get you where you want to go and keep you there. ;)

What I presented is a piston suitable for extreme high speed setups, it's not at all suitable for OP's setup, it's actually too light. By too light I mean it might actually hurt compression efficiency with heavier BB's. I just wanted to show an example of how light even full steel rack pistons can be. For OP's setup the stock piston is probably strong enough, CYMA nylon pistons are actually quite durable.

 

I have also grown a bit tired of excessive ROF, my latest build does a very calm 21rps, it has ridiculous trigger response and is set up for range and accuracy and optimized for heavy BB's. I guess I have a different perspective on teching than you have as I find teching guns almost as enjoyable as using them on the field.

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I enjoy the learning process, and it's been a steep learning curve being from knowing nothing to getting good performance out of my guns. I'd probably spend more time trying new parts and pushing the limits a bit if I had more actual time...

There's nothing that can't be improved with putting a bit of effort in. That's why I port my own cylinders to suit barrel length and BB weight. It's the little things that add up.

Would you mind sharing a few details about your latest build? That sounds very much like the sort of thing I regard as high performance. :)

Back to the OP, you can go a couple of ways. Until recently the accepted way to get a good balance between trigger response and ROF was a high torque motor and high speed gears. SHS Hi torque and 13:1 gears is a proven combination. The new generation of high speed /high torque motors combined with 18:1 gears offer similar and sometimes better performance than the Hi torque /13:1 set up. I've used a Lonex A1 with 18:1 gears and you'd be hard pressed to tell the difference between the two. I've had the Tienly 40000 recommended to me which should offer superior performance to the Lonex, and will be my next build.

With any of the above, on 7.4v,Mosfet, 16awg wiring and Deans connectors you'll get great trigger response, about 20rps, and on the M130 spring and a 25g piston assembly no chance of pre engagement.

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High TPA motors aren't obsolete yet, the new "high torque and high speed" motors are simply explained low TPA armatures in strong neo magnet cans. They have probably improved the quality on the armatures compared to the low TPA neo magnet motors we had a decade ago, but I wouldn't say anything revolutionary has happened. I will agree that they perform better than the low TPA neo magnet motors from before, they probably have a different wire gauge in the windings, slightly stronger magnets and the magnets probably sit slightly closer to the armature.

 

In my latest build I put a G&G 27TPA armature in a King Arms (same OEM as older SHS I think) neo magnet can and it has quite impressive torque. It pulls a Guarder SP120 spring on 12:1 ratio gears full stroke and does 425fps, field legal with full auto at the local field with a 15 feet MED. My TM EG700 armature in a similar KA neo can offers even better trigger response though, probably because the armature is of higher quality.

 

The setup you recommend should work very well, I definitely recommend the Tienly motor over the Lonex motor. I have had overall negative experience with Lonex motors, they're not good motors from my experience. I've tried two different generations of both A1 and A2 motors and they all overheated and ate brushes in setups that barely heats up my Guarder ITU and Tienly GT-35000.

Edited by Lefse

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I enjoy the learning process, and it's been a steep learning curve being from knowing nothing to getting good performance out of my guns. I'd probably spend more time trying new parts and pushing the limits a bit if I had more actual time...

There's nothing that can't be improved with putting a bit of effort in. That's why I port my own cylinders to suit barrel length and BB weight. It's the little things that add up.

Would you mind sharing a few details about your latest build? That sounds very much like the sort of thing I regard as high performance. :)

Back to the OP, you can go a couple of ways. Until recently the accepted way to get a good balance between trigger response and ROF was a high torque motor and high speed gears. SHS Hi torque and 13:1 gears is a proven combination. The new generation of high speed /high torque motors combined with 18:1 gears offer similar and sometimes better performance than the Hi torque /13:1 set up. I've used a Lonex A1 with 18:1 gears and you'd be hard pressed to tell the difference between the two. I've had the Tienly 40000 recommended to me which should offer superior performance to the Lonex, and will be my next build.

With any of the above, on 7.4v,Mosfet, 16awg wiring and Deans connectors you'll get great trigger response, about 20rps, and on the M130 spring and a 25g piston assembly no chance of pre engagement.

I really enjoy learning aswell, I like to face challenges and overcome them.

My latest buid was a really, really basic GB upgrade - stock CYMA reinforced gearbox with an M120, Energy PolyCarbo 7 teeth psiton, Military Action piston head with 6 holes, an E&L Gen.2 AK one-piece cylinder and head assembly, some off-brand Nozzle with O-Ring, of course AOE was corrected.

The build came out rather disapointing as I ironically ran out of proper shims (the gears are so-so shimmed), the build has a terrible trigger response, there are not even deans and a MOSFET

Edited by F1ERRI

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