PTW - Questions
 

Some PTW questions...

Some of it's a bit noobish...sorry.

I have a PTW motor...I'm pretty sure it's a 480. I can't recall or find the post that I think McGuyver made that described how to tell one from another. It might not even be on this forum (vs. Systema forum, etc...). If someone knows off hand how to tell a 480 vs 490A vs. 490B apart...please let me know or point me to the right thread.

On one of the motors I have the brushes are worn about halfway through and are starting to look pretty raggy where they contact the comm. The comm looks pretty good...no nicks/scores/gunk (inspecting through the brush hoods with the brushes out). How long can you go with the brushes before they're done? Just use them until they stop working...or is there a don't use past this point sort of thing like a brake pad? I don't know that I've ever actually worn out a set of brushes.

When it comes time to replace them, if I understand things right I'm going to need to replace the brush hood with a 490 brush hood and get 490 brushes? Is that correct...and what's the local Canadian source for them (DoubleTapTactical?))

Re. getting/building another PTW...and I have not kept up with all the generations of Systema builds.

Are the Systema SCK's still hit and miss high lemon rate thing? Do the issues stem from electronics and motors or actual fit and alignment of the rest of the parts?

Are the electronics/motors compatible between 2008 and current SCK's. Not mix and match per se but rather using one set in lieu of another. i.e. I have a bunch of extra 2008 boards, spare motor and mechbox....I know all those work. If I have issues with the current SCK will the 2008 board fit the current body...will the motor...etc..? Or have they changed the dimensions somewhere (I remember reading something about that a while ago).

If you have a picture of the motor, I can tell you what it is, approximately when it was made and the winding type. 11t is 490a and 14t is 490b as stamped on the amrature.

If it is a 490, you should replace the brushes when they are half worn, or when the brush spring is at 90 degrees to the hood. You only need brushes for the 490. For the 480, you need a brush hood set, as well as brushes. Or you can harvest those parts off a dead motor if you have one available.

Chris can get you the brushes, I think he normally stocks them.

Current problem with 2012, outside of the motor, is the cylinder shell. But that is not an issue if you use an older cylinder. Kits have always had off-spec parts, and nothing in my experience has made me change my assessment over the years to avoid the kits, unless you have them properly assembled and the off parts replaced or modified.

Everything is compatible, except older cylinders in the Supermax. One thing you can count on is that after Gen 1, all dimesions are the same. I can take a 6 year gearbox and it fits perfectly in a 2012 body.

Thanks!

...I was going to PM you all that, but didn't want to impose :)

With the 2012 cylinders it was something about them being too thin and ballooning or something like that right?

No, it is a flaw in the manufacturing. It is not repairable.

What they did was machine a stainless steel tube. Then, the machined the core which contains the piston guides out of aluminum, and pressed it all together. The core was machined with an ID too large for the piston, so this piston has too much play. What happens is that the piston wiggles around, and when under spring tension, reduces the amount of gear lash between the piston rack and the sector gear.

In a new cylinder, it wil work for awhile, and then when the rack gear teeth get worn a bit, specifically the last tooth, the sector gear no longer mates the rack and you get an awful grinding noise and no joy.

I had thought perhaps a strip of Teflon or similar material glued to the top of the piston might be the trick, but getting it simply hasn't been worth the effort for me at this time.

I see. Basically piston flex but as a result of slop. Interesting. Hopefully it can be gutted for spare parts, etc at the very least.

I would just buy an FCC cylinder. Way less money.

Uh oh!! And here I went and bought a M4 Systema M110 (stainless-blue) from RedWolf awhile back when they were on discount thinking it was a good deal. :(

I needed a lower FPS cylinder and the old aluminum ones were simply n/a everywhere at the time. It's still NIB and unfired but your post now has me worried some mcguyver. Should I be looking at leaving it that way and going after a FCC version instead? I doubt RW or even Systema themselves would care to honor any kind of manufacturer's (proven) defect warranty so I am likely SOL. :mad:


'Fly
(not a happy camper ATM...)

If you look on King Arms web page they now are making PTW cylinders. Don t ask how they are I just noticed them lastnight lol.

You can tell if your cylinder is going to be an affected one.

When the cylinder is at rest, take a small flat blade screwdriver and try to push the piston around. If it moves up and down, on the order of 1/8" or so, it is bad. The internals can be salvaged, just get a replacement shell.

If you have on that has been used, but are unsure, tear it down and look at the top of the piston. If it shows wear on the top surface at the back, it is an indicator it is slopping around and that wear comes from the aluminum core at the end of the piston chamber.

Not all cylinders are bad, some have been good from all accounts and some bad.

Short of taking it apart to fully relax the spring pressure, I assume you mean to simply try and move the piston around by placing the screwdriver pressure on the piston rack? It's the only thing I have access to through the port on the bottom of the cylinder so I am guessing that's what you are referring to?

If so, then I seem to have no movement...or at least none that I can tell. :D

Regards,

'Fly

You are correct Fly.

The movement in the bad ones is quite pronounced.

Another telltale sign is the extreme wear on the last tooth of the rack gear. It usually takes only a few thousand rounds to wear it round or with a track cut into it by the sector gear.

Thanks M.

There's no evidence of piston slop, though it will rotate a bit but that's normal. Also, I don't know if this is normal or not as I never really looked that closely at it before, but the very last tooth on the piston rack is almost double thickness at its apex compared with the others. Seems like Systema wanted to reinforce that particular tooth over the others.

At any rate based upon your advice, I think mine's a good copy after all. :D

Another question: do these cylinders come pre-lubed or should I be looking at applying some myself? From the factory, the piston rack looks pretty dry to me so no telling what if any lube is inside the shell? Yes, I am a bit of a PTW noob myself. ;)

Many thanks!
'Fly

The compression chamber needs lube. On older cylinders, Systema used their cylinder grease, basically a white lithium grease. But this reacts with the stainless and turns black and gritty very quickly. Perhaps a switch to silicone grease would be better. It is something I will tinker with by next year.

Cylinders need to be relubed regularily, like 1-2 times per year, based on usage.

Some grease needs to be on the piston guides and the spring and guide. For the spring, I use Systema gear grease, and use the cylinder grease for the piston guides.

I was actually thinking about trying Frog Lube paste. Any experience with it? I've heard nothing but great things from the RS crowd so it can't be that bad for us "less lethal" folk? Metal on metal friction is a reality in either case. All my guns need a season-end cleaning and methinks this would be a good time to remove the existing petroleum-based lube and replace it with the green stuff. I generally go very light with the lube anyway - only applying as little as needed, and for the most part, I've been using this pure silicone oil called SalShield on all the moving metal parts. Lithium grease tends to trap crud so I use it very very sparingly and only where the oil cannot be used.

I guess that Systema didn't put any lube in their new cylinders then? It does appear dry at least from the outside so I guess I will have to open it and find out. I would have hoped they at least applied some form of lube at the factory rather than requiring the user to take a new cylinder apart before ever using it simply to add lubricant? Ahh...the wonders of airsoft mechanical "engineering" (sic)!!

'Fly

Lubrication is a very complicated science.
RS lube is an entirely different application than AEG lube.
High heat, high pressure, metal on metal friction, vs low heat, low pressure, air sealing, rubber on metal contact