Wiring a G&P Crane stock & batt - a proper job

[Zhang]

After seeing the AAA battery in the stock tube, I went home and tested out the fit.

 

I used two different buffer tubes: A G&P crane stock tube, and a normal AIM m4 buffer tube.

 

4 AAA batteries easily fit within the diameter of both tubes. They are somewhat of a tight fit in my AIM buffer tube, but in the G&P they move about freely.

 

However, fitting an 4x2 8 cell 9.6V battery into the AIM tube is impossible. This is because the AIM tube is built for traditional receivers, where the stock tube has not been cut down to a 3cm size. As a result, the ridge in the buffer tube that the washer sits on stops the 4 AAA cells from advancing any farther down the tube.

 

The G&P tube will have no trouble fitting a 8-cell AAA pack. Because the G&P crane stock requires the stock tube on the receiver to be cut down, the custom buffer tube provided in the kit has the washer ridge located much farther down the tube. It's enough to fit 12 AAA batteries in there when the stock is retracted. Fitting a 16 cell pack, however, means you can't fully retract the stock.

 

Since the G&P crane stock does not have the hex key hole to mount the buffer tube plate, a rubber buttstock pad is probably needed to cover the hole and keep the batteries inside.

 

Battery capacity aside, my only worry is that AAA cells may not offer enough discharge. You may be able to get 15 amps max out of the newest ones... nothing compared to the 20-30 amp rates of bigger intellect and Elite cells.

[Hilts]

Battery capacity aside, my only worry is that AAA cells may not offer enough discharge. You may be able to get 15 amps max out of the newest ones... nothing compared to the 20-30 amp rates of bigger intellect and Elite cells.

<{POST_SNAPBACK}>

 

Perhaps with a stock or 1J spring and a high torque gear set you wouldn't need so much current to get the gearbox spinning. Just a thought .

 

Tommygunn has inspired me with this thread - I'll try and sort some pics over the weekend of my 'frankenstock' - Star Crane on a G&P buffer tube on an ICS receiver!

 

Cheers

 

H.

[Lance Jackass]

Thanks zhang yeah i'm worried that the little AAA batteries won't have enough power in them to get my gun firing. But if someone else has managed it, there must be a way!

[Tommygunn]

Zhang,

Apologies, I was a little harsh in my reply. In hindsight it wouldn't be a bad idea at all to chop down the receiver mounting tube to allow more freedom for the compressed wires etc. I might try this in the near future.

I might also go mental and try triple A's but as we have all mentioned the discharge rate concerns me.

If 16 cells are mounted in parellel to make a 9.6V and double the mah, will this also double/up the discharge rate? Anyone?

 

EDIT: scrub that. I don't have a G&P stock tube.

Zhang, You have to chop down the receiver tube to fit a G&P stock tube as you have no choice. The stock tube simply won't fit otherwise.

[Lance Jackass]

If 16 cells are mounted in parellel to make a 9.6V and double the mah, will this also double/up the discharge rate? Anyone?

 

I wouldn't have thought so, but i'll find out.

 

Edit: Sod it, well over my head http://www.gizmology.net/batteries.htm

[Tommygunn]

Although it doesn't give a confirmed 'yes' the following extract seems to support the fact that in parallel you get a multiplying of the grunt effect i.e. discharge rate:

Hooking batteries in parallel will give you the same voltage as a single battery, but with a Ah and CURRENT CARRYING CAPACITY equal to the sum of the capacities of all the batteries. For example, three 12v 20 Ah batteries in parallel will give you 12v 60 Ah. If each battery could put out 200 amps max, three in parallel could put out 600 amps max.

Does anyone else concur?

[Hilts]

Yep, that's the way it looks to me also

Current draw is divided up amongst the batteries the same way that capacity is combined. In parallel, each battery only need supply a fraction of the total current drawn by the load; in series, each battery must supply the full current. Thus, a motor drawing 150 amps from three 12 volt batteries in parallel will draw 50 amps from each.

The only thing is, I can't find anywhere that shows what the constant is for those batteries (usually expressed as a multiple of the mAh ie C15 would be 15A for those cells).

 

H.

[Zhang]

I've made a diagram showing why crane stock tubes may be necessary. There's a tiny ridge on which the washer rests. That inner ridge prevents a 4-cell wide AAA pack from fitting any further down there. Thus crane stocks that require a receiver tube modification give a lot more space for AAAs than regular buffer tubes do.

 

 

Concerning the batteries, if running two packs in parallel doubles the discharge rate, there should be nothing to worry about. The latest AAAs should be able to put out 8-12 amps, so getting around 15-20 amps would mean a pretty decent battery.

[Lance Jackass]

Brilliant! Now just to buy the parts

 

Thanks everyone.

[Hilts]

Awesome! Any hints to where you sourced the plastic cell holder thing?

<{POST_SNAPBACK}>

DEN Trinity have them in - $10 each. Search for product number STK062AC1.

 

Cheers.

 

H.

[Tommygunn]

$10 jesus! If you've got time to spare just put a wanted in your sig(like I did) or the classifieds.

[Daikuma]

Your work is excellent sir.

 

Now for the pop-quiz-hot-shot moment.

 

How would I take the modification you have done and apply it to the G3 SAS Rear Cap so I can mount the Crane Stock to my M41 Offizier FS?

 

I kneel to your brilliance!

[Tommygunn]

I dunno, I don't have a G3 SAS.

[Mig1]

Sorry to be a bother, gents. Could someone repost the 16 x AAA cell pics as they appear to have expired, as well post some after action reviews?

 

If a new thread would be more appropriate, that would be great as well.

 

Thanks in advance.

[Tsunami1977]

Tommy, SEI IL NUMERO 1!!!!!

 

Very professional work!

 

but i have a little challange for u.....

 

 

but i wanna make a new TREAD

[Tommygunn]

Mig1,

No idea where the pics have gone but maybe Tsunami's idea looks useful.

 

Tsunami,

Gracie mille.

I take it your having trouble getting the battery and plug in the stock tube?

Can you do a pic with the battery removed but in-line above the stock tube for a length/size comparison? Also so I can see the makeup of the battery pack.

I presume they are AAA cells?

[Tommygunn]

I thought I would update this thread with the latest developement.

 

I have decided to switch over to Lipos and have bought three sticks of 7.4Volt Turnigy Nano-tech from Hobbyking.

I have therefore elected to locate the battery in the buffer tube and it has allowed me to eliminate the extra wiring and fuse, up front, that remained from when I had the PEQ battery box fitted. Therefore everything is now wired to the rear as shown in the photo below.

 

 

 

You will notice that I also considered several other methods of containing the fuse, a panel fuse holder for containing 5x20mm fuses and an inline fuse holder for 'mini' blade fuses. Both of which would fit in one of the two storage compartments of the Crane stock.

However, in the end, I decided to go with the most compact method using a standard blade fuse in the buffer tube alongside the battery. All metal components of the fuse assembly have been covered with plenty of shrink tube.

 

This next photo show the completed assembly with 4mm bullets attached.

 

 

 

The last photo shows the space available with the stock as if it were fully collapsed. In this state there is approximately 15mm between the back end of the buffer tube and the inside face of the stock. Of course this is not enough when the battery, plugs, wire and lipo alarm are in place, but, with the stock slid out to the first notch, there is plenty of room.

 

 

 

The lipos should arrive this weekend or early next week, so I'll have to wait till then to try the pudding.

 

Cheers,

Tom.

[Tommygunn]

I received my batteries today and they seem pretty good. They put out an equivalent rate of fire as my GP, Sub C, 3000mah, 9.6Volt pack which is great and in such a small package.

 

Anyway, I did some mods to the wiring harness by shortening the wires overall and directly soldering the positive bullet to the fuse spade, saving some space and fiddling about.

You can see that one of the packs has had its plug removed and replaced with 4mm bullet sockets and the wires shortened.

 

Everything fits perfectly inside the stock and any bulges in the wire or connectors, outside the confines of the buffer tube, is easily accomodated in the storage cavity of the stock, which has an open channel moulded into. Of course, as previously mentioned, I can't fully collapse the stock but that is no big deal.

 

I also had to put some tape over the horns of the lipo alarm as it is simply too loud. Great for when I'm flying my Quadrocopter but not so good when its next to your ear.

 

Tom.

 

 

[Apex]

Nice work Tom

[Tommygunn]

Thanks, hope it helps.

Tom.

[midas]

I have just done a similar set up for my XM177, although mine are 11.1 LiPo's and an ASCU. This set up is ideal really so the battery and other sensitive parts are inside the tube/ stock.

 

The down side to that is they are next to your face but so long as they are properly protected things will be fine.

 

[Apex]

Thanks, hope it helps.

Tom.

 

This thread is the one i followed when i had a m4 and crane stock - never stop learning

[Tommygunn]

Just a little update.

I have rewired my M4 with 18awg wire, due to mosfet installation and associated space issues, and fitted a G&P 6 position buffer tube because of the longer and wider internal cavity.

The Hobbyking 3S 168mm long batteries now fit nicely, albeit with the stock out two notches when a battery is installed. I can live with that.

As you can see from the photos the battery plugs and fuse fit nicely in line with the buffer tube.

 

The lipo alarm fits perfectly into the stock compartment. You may have noticed that I have desoldered one of the tweeters from the alarm so as to allow it to have a better fit

 

I also sliced the corners off the blade fuse to give it an improved profile when sandwiched between the buffer tube and battery.

 

Tom.