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Winding your own armature advice

29K views 90 replies 19 participants last post by  jimc1951 
#1 ·
I have been wanting to try winding up some of my own T- Jet armatures for a while and finally decided to give it a try. Ive spent countless hours looking for information on this subject, (there doesnt seem to be a whole lot of info out there) along with talking to a friend who winds his own drag arms. He walked me through the whole process and I understand it totally, but my question is what gauge or gauges of wire are suitable for road racing? Im looking for a good combination of torque and top end hp, maybe 4 or 5 ohms? Something a little hotter than a mean green. I only home race, so following any class rules isnt important to me.

Thanks,

Dyno
 
#47 · (Edited)
Keith, thanks again for the advice. :thumbsup:

My track only has 7 foot straights and some tight turns, including a hairpin. However Im in the process of helping a friend build a fairly large 4 lane at his house with 15 foot straights. I dont have any 37 gauge wire. I have a spool of 36 now, and a spool of 38 coming on monday. How does 10 feet of 38 sound. It should be about 4.8 ohms I believe. One more question. Whats the advantage of a double or triple wind?

Thanks, Dyno

pic of my layout
 
#48 ·
Dyno,

Without going into a bunch of DC Electric Motor Theory, which has been covered very well here on HobbyTalk by several members/HO racers ( excellent job! ), the 38 gauge can not transmit the same maximum amount of current ( expressed in amps ) as 37 gauge or lower numerical wire sizes. This then affects the ability of the armature pole to produce a magnet field which then propels it to the magnet. The larger the wire ( smaller numerical wire gauge ) the greater the amount of current it can carry and the stronger of a magnetic field it can produce which equals a faster spinning, higher torque motor.

Of course this is slot car racing and sometimes the general rules of physics appear not to apply, but, that is only because there are so many variables that must be accounted for.

The one big drawback of the pancake motor design is the gear train. Inline cars have two gears compared to five in the pancake motor car. Consider this when comparing the power of the two types of motors; think of the massive amount of energy those five gears consume!

In principle two wires of a smaller gauge will carry slightly more current than a single wire that is three gauges larger. A 40 gauge double wind will be equivalent to a single 37 gauge wind of the same winding dimensions.

Keith VanAtta
 
#51 ·
Keith,

Thats the best explanation I have heard regarding wire gauges vs power. It makes perfect sense the way you explained it, Thank you. I have a 2 lam blank and a comm plate sitting on the table waiting for my new wire to get here. Im on my way to The Home Depot to pick up a clamp-on Vice to hold the winder. Stay tuned for round 2 of rookie armature winding attempts coming soon...

Dyno
 
#53 ·
Great Thread Guys!

Iam wondering if its possiable to wind too hot of a motor for a givin size wire. Like a 0.75ohm motor would be 34awg wire at 4 ft long. Is that too much power for that size arm?

Or 34awg wire at 2ft ends up 0.37ohms. Is that even possiable to do? Will the wire handle that much? Or would a bigger wire be mandatory?

Blake
 
#57 ·
So for low ohm arms, do a double wind arm. But how do you do that? Is it 2 seperate peices of wire per pole?

How many passes can you get out of a singe wire 1ohm 2 Lam motor? Would 5 passes be asking too much?

My plans is just to build drag arms. Iam really interested in building a couple Outlaw Tjets.
 
#63 ·
Yes, two separate strands of wire. At 1ohm, you will get way more than 5 passes. Don't free rev a low ohm motor!!! It will reduce it's life span. If you are building an outlaw, start at 1ohm and work your way down from there, you'll find out quickly what likes to break. You'll also need a nice stiff wheelie bar. Try not to crash.......or, you'll have a pile of parts!! :eek:
 
#64 ·
Started on the chassis for the Tjetsgrig arm today,Cleaned, polished brass, Boiled it, checked the flatness & straightness of all the shaft holes, got the gage pin rear axle & gear train together, shimmed & installed. The chassis is in the lapping tank now. I will get it cleaned up & some pics soon. My goal was to have it broke in, tweaked and ready to race by next weekend. Just have to see how everything else goes. I am giving this baby every chance to be my #1 bullet.

Boosted
 
#67 ·
Here is a couple of pics as promised, just starting to break in the arm now on low power.

I do have a question on a "Fray" car build technique. I have seen several chassis that the brush springs have a slight blue tint to them as though they were heated & possibly tempered. Anyone have an insight on the process to do this correctly, I assume it is done to get more spring tension for the brushes or to keep them from relaxing under heat?

Don't look too close at the body, I am going to fit it to this chassis but I hope to pick up something that looks better in the future. My problem is there is nothing around here, as far as Hobby shops that carry any HO stuff, so I pretty much have to find what I want on the internet, order & ship.

I almost have my 1st attempt @ a 17 ohm arm wound, I cant wait to see how Jim's arm runs & then compare my wind to his. I actually rewound one pole after I saw his arm, They truly are works of art. :thumbsup:

Boosted
 

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#68 ·
Ok Boosted my first question is what kind of car are you trying to build? A Fray rules car, a Drag car, or just something to run at home with no rules?

As fare as the brush springs go on a Fray style car you don't need much brush tension (more = dynamic brake) if you are using Wizzard Brushes all you need is about 3/4 of the brush sticking through the chassis brush hole. In most case's a High ohm road race car you want the car as free as possible. You also want to make sure the chassis and plate holes are as tight as you can get them and still have everything move VERY freely ( NO Wobble) this helps make the car quiet and lets the gears last longer because they don't chatter. when putting the top plate gears on make sure they are on flat (RTHO gear press works best) you want to have minimal up and down movement so press the pinion on so it has .002" to .003" clearance up and down movement same with the arm because if the arm has too much up and down movement your brushes can push arm up and down and make the car feel inconsistent.
 
#69 ·
We run "Fray" rules cars, but about the only checking that goes on is to ohm the arm, 16 ohm avg, checked at room temp, along with checking the magnets, People run Dash, JL & we even have a guy that runs Super II mags, otherwise the cars closely resemble "Fray" built cars. So yes we have rules but we dont get overly involved in tech inspection unless it's something quite obvious, bearings, weight or the lack of etc. I agree on the gear train, I have a lapping process that works well & the cars roll very free afterwards. I had just seen a couple of the cars with the blue looking springs & wandered if they were somehow tempered for stiffness.

Tjetsgrig's arm likes a little more brush tension than I normally run, It really came to life after the brush tweak, I Still need time to tweak the shoes & some more run in time, only had it on 14-16 volts as well, that little bomb is going to fly on 20 volts
 
#71 ·
I guess I was curious as to the rules because I know Fray, ECHORR, Quarrel do not allow rewind arms no matter what the ohms are, but it really doesn't matter if it's local club racing where its just home rules. If there is any questions you have in car prep I might be able to help alittle
 
#73 ·
The vented gear plate is just a build tool used to check the air gap between the magnets & the arm, as for the white gear it is std size, it is a nylon gear that I bought several a while back, they lap very well & you wind up with a very smooth & long lasting gear train afterwards. I have a really "modified" brass pan T-jet chassis (think flex master) that I have been working on for a while, its going to get the first double wind arm that I get done. Its got all the normal setup work into it plus some machining for Super II brush cups & to lighten & ventilate it as well.

I will try to get some pics of it up soon.

Boosted
 
#74 ·
Hey guys, i just did my 1st arm this weekend. 3ft of 38, which got me 1.1ohms. But i belive i made a mistake. I was looking at my stock arms and noticed that where the wires are tied to the comm plate, i reversed them.

So does this mean that the motor will run backwards? Thus only be used in 4 gear cars?
 
#79 ·
I would be winding as well, but I am too busy racin, showing the rear bumper of that new little rocket to the local crew. I have already heard several comments that their getting tired of seeing it. HA ha. Nothing like a new bullet in the stable.

Their all waiting on it to slow down or burn up, it gets faster every time out & is now running as cool as ice.

Boosted
 
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