sorting out used Systema Magnum motor....

[philosopher]

My used Systema Magnum motor arrived this morning.  With the motor I bought a used V3 gearbox in pieces.  What the seller did not say is that he was including a full guarder M150 bore-up kit with the gearbox!  Gears, bore-up cylinder, piston, piston head, bearing spring guide, etc.  Whoop!!!  It is from an AK47, but those are still good parts.  It is not quite all there -- the 150 spring was not included.  I only casually inspected it all, but I think most of the rest is all there.  Still, what a score for $45 for the whole thing!

However, the motor arrived shorting out.  After some testing it quickly became clear that it was shorting through the red (powdercoated?) aluminum motor cap.  For those of you not familiar with the Systema Magnum motors' design, both the (+) and (-) metal motor wire tabs, brush housing, etc are screwed directly to an aluminum cap, and the only insulation is the paint on the aluminum.  If (when) the paint chips or anything like that the (+) and (-) will short together, or to the housing, or both, or to a passing idiot, etc.....

Why on earth would they design it like this?  Seriously, for one of the "best motors on the market" it has some major design flaws.  I added some insulation via a single layer of some hi-grade electrical tape, and that solved the problem for now.   Still, I am absolutely floored at how delicate these motors are built, and how incredibly easy it is to short one out. 

I am going to treat the tape as a temporary fix, a band-aid, with plans to re-inspect whenever I think of it -- it is easy to do this on an AUG.  Remember that my old motor broke before I could test my newly installed Guarder M150 bore-up FTK.  How funny that I now have two of these kits.   I like having spare parts sitting around.  It really takes a whole lot of pressure of me as a learning/fumbling air smith.   

Also, one of the "special" non-conducting screws arrived broken - it actually broke when I installed it, but (and you'll have to trust me here) I was doing it correctly and with the correct torque.  Either way, I will be needing at least one of these non-conductive M3x10 cap-end bolts.  Because of temperature issues, I don't think I can use a simple nylon bolt.  I think these might be made out of Bakelite, or some hybrid ceramic like that.  I know Systema sells these, but I really don't want to wait two weeks and pay $20 in shipping for a package of two stupid little bolts from Hong Kong.  If anyone has a spare, or knows of a US supplier, I would appreciate the assistance.

Peace and grease.
-Philosopher

EDIT:  regarding those screws.  RedWolf.com sells them  But like I said, I would like to get them locally (in the USA) if possible.  Note that they screws are called "Systema Two Piece Reny Socket Screw Set for Magnum & Turbo Motors."   Reny?  Yeah -- it is a special plastic-like substance that is fairly strong with a fairly high melting temp (108°C).  I think I read that Mitsubushi owns it.... Oh well.  Since RENY is about 3x more strong that the nylon screws with almost double their melting temp, I probably should not replace a RENY one with a nylon one.  He he he.

[Joaz]

Why on earth would they design it like this?  Seriously, for one of the "best motors on the market" it has some major design flaws.

Maybe because someone decided that an anodized aluminium end bell looks better

However the plastic screws are AFAIK M3x10. I use some spare ones made of Polyamide. 

[wolfdragon]

I fixed mine and bruin757's magnum that had the asme issue by doing the following:

1. Remove the brush springs and brushes, unscrew the TAN spring wrap posts.
2. Remove the BLACK screws. Be uber careful, these like to break and it's a PITA to replace them with metal screws and keep everything isolated.
3. You will have two pieces of silver metal for each side, a flat thin one for the bottom and the heavier formed one, together these make the brush channel.
4. Using the flat pieces of metal as a guide, cut out two paper "spacers" from 20lb printing paper or heavier.
5. Rub dielectric grease into the paper gaskets, it help with too many things to list here but is not entirely necessary if you don't have it on hand.
6. Reassemble the back of the motor, be careful how much torque you put on the Black and Tan screws because they aren't exactly strong.

Now the paper will be between the anodized end bell and the brush channels, thus isolating the brushes from themselves and the end bell.

Take your time with this one, it took me a little while to figure out what works best and making it look nice and neat.

[Moulde]

Only one of the plastic screws broke?
Then just throw in one made of metal..

I will only short if you install two metal screws..

[philosopher]

However the plastic screws are AFAIK M3x10. I use some spare ones made of Polyamide.

Where did you purchase these?

I fixed mine and bruin757's magnum that had the asme issue by doing the following...
Now the paper will be between the anodized end bell and the brush channels, thus isolating the brushes from themselves and the end bell.

That is exactly what I did with hi-grade electrical tape. 

Only one of the plastic screws broke?

Then just throw in one made of metal..
It will only short if you install two metal screws..

Not quite correct.  If you do this then the motor housing -- and thus the entire gearbox will carry a charge, and that is an unacceptable solution.   Thanks for the idea though.

Thanks all for the quick input!
Peace and grease,
-steve

[Joaz]

Where did you purchase these?

I got them from a screw manufacturer but as I'm not in the US I cannot help you that much.

You may also find those in RC shops. Those screws are sometimes used  to reduce weight in RC planes.

[Gandolf]

However, the motor arrived shorting out.  After some testing it quickly became clear that it was shorting through the red (powdercoated?) aluminum motor cap.  For those of you not familiar with the Systema Magnum motors' design, both the (+) and (-) metal motor wire tabs, brush housing, etc are screwed directly to an aluminum cap, and the only insulation is the paint on the aluminum.  If (when) the paint chips or anything like that the (+) and (-) will short together, or to the housing, or both, or to a passing idiot, etc.....

Why on earth would they design it like this?  Seriously, for one of the "best motors on the market" it has some major design flaws.  I added some insulation via a single layer of some hi-grade electrical tape, and that solved the problem for now.   Still, I am absolutely floored at how delicate these motors are built, and how incredibly easy it is to short one out.

This would truly be a giant design flaw!!!  I will try and confirm it here too...  The Systema motor with its super magnets might be able to generate easily greater than 300V transient spikes which can ionize air and arc over a fair distance.  If that is all true, it would actually explain many, if not most, failures.

I have a very new Systema motor I can easily do breakdown testing on.  I suspect this investigation will be a sad one...  However, an after market thin insulator might be very easy to make and totally solve it!!

Gandolf

[philosopher]

I am EXTREMELY happy to see this thread picked up again. 
Gandolf, have you had a chance to check out your motor? 
-Philoospher

[TriChrome]

My question about these motors is if I should run my Magnum as-is, then wait for it to break OR do this mod right off the bat? Would there be any harm done to the motor if I wait until something breaks/shorts on it?

[Gandolf]

Gandolf, have you had a chance to check out your motor? 

Oops!!!  I totally completely forgot 

I will pull out the 10kV Bertan precision HV power supply tomorrow and get the HD cam going too.  PM me if I get all derailed and forget again 

Gandolf

[Gandolf]

I will pull out the 10kV Bertan precision HV power supply tomorrow and get the HD cam going too. 

And the answer is 24V and it shorts all out.    The youtube video is here:

http://www.youtube.com/watch?v=yKAfPCg1VMI

The powder coat (actually it is anodized) is a terrible insulator.  I don't know what they were thinking.  Voltage spikes can easily break though and soft short it.  I can only assume that at high currents the shorts just keep blowing clear.

Here it is at low voltage after the high voltage test:

http://www.youtube.com/watch?v=rQu0j63Nwv4

at about 3 volts it blew the fuse in the meter on the right measuring current 

So all your worst fears about the red 'insulation' breaking through are true.  Somebody will have to write a letter to Systema asking them what the "theory" is there...  I think somebody needs to make a insulator kit...

I am stunned...

Gandolf

UPDATE:  I added Kapton tap between the brush holder and bell housing.  I also removed the rough flash edge around the screw holes.  200V with less than 1uA of leakage current now:



I can't help thinking that there was supposed to be an insulator in there from the factory?  Do old Systema Magnum motors have one?

[RiotSC]

SystemA was never great at insulating its motors.  Before the switch to anodized aluminum endbells, SystemA used metal screws to secure the terminals and plastic end bell onto a metal retention ring inside the motor can.  The only insulation between the terminals and the screw-linked retention ring was the paint on the screws/washers...  After the switch to anodized aluminum endbells, the insulation is the anodized layer...    I think the insulation mod is the first thing people should do when they get their SystemA motors.  We probably would not be hearing about the Turbos and Magnums burning up if SystemA just insulated the terminals from the endbells from the start...

[Gandolf]

Hi,

I am thinking McMaster-Carr # 96100A115 would do the trick.  They are hard fiber washers that are 0.125 ID, 0.313, OD, and 0.013 thick.  They only cost 8 cents each.  You would just put the washers between the brush holders and the end bell and it's all done.  The metric version is thicker and does not look like it would fit as well as the English size.  A fast, cheap, and easy fix.  I'll order some up if anyone needs any.

Gandolf

[philosopher]

Gandolf,  Thank you for your testing.  Great results!

"96100A115 -- Black Hard Fiber Flat Washer #4 Screw Size, 1/8" ID, 5/16" OD, .013"-.017" Thick"

I don't think this will work best.  I do not like the shape.  The material might be perfect, but the shape is wrong.  Instead I think it would work better to trace out the bell housing and hand-cut your own insulation.  I made my own with good success so far:

I made a spacer out of HD electrical tape and put it between the brush housing and the motor housing.  I was careful to let it wrap around the brush housing, making a slight "L" shape as it curves up so it insulates all the way around.  It insulates both on the horizontal and vertical planes).  I am away from home on business for the weekend.... I really should post some good pictures, and I will try to do this on Monday.  I am not sure if I trust the electrical tape fix, but it certainly has solved the problem for now. 

I like Wolfdragon's suggestion of using dielectric grease on heavy card-stock paper, and it might last longer than electrical tape.  Maybe.

Peace and grease,
-philosopher
 

[Gandolf]

I was thinking of a super simple, cheap, and easy bolt on solution that might be sent to large numbers of folks.  Of course, a nice die-cut insulator would be nice too, but that would cost more than $10 per 100    If anyone has a die-cutter thing, they sell the stuff in sheets.

It has to be something that will not squish down and can take heat.  The fiber washers will probably last forever and nothing can go wrong there.  Obviously, it is the nearest fit off-the-shelf part as opposed to a pretty custom part though.

Note that the die-punched brush plate in my case had significant burrs on the hole edges when it was stamped too.  That forms a knife edge that would have cut through the tape.  I trimmed it off.  But the washers have the strength and distance not to care about that.

Gandolf