# T-jet Armatures



## dtomol (Mar 30, 2005)

I have an idea, can the lamination of the armature be drilled to reduce the weight and allowing it to rev ups faster. Inquiring minds want to know.


----------



## smalltime (Jun 3, 2006)

dtomol said:


> I have an idea, can the lamination of the armature be drilled to reduce the weight and allowing it to rev ups faster. Inquiring minds want to know.


I would not drill the laminations. Too easy to compromise the windings.

What I do is reduce the O.D. 

This is easily done with a dremmel, a cuttoff wheel, and an old slave chassis.

First, cut a notch in the side of your slave chassis that allows you to access the arm lams. Then use the side of your heavy duty cuttoff wheel and place it so that you are spinning the arm AND grinding at the same time. It will take some practice, but you will get pretty good at it.

Be careful not to grind on the comm keepers to much, but you can reduce the diameter quit a bit using this technique.


----------



## dtomol (Mar 30, 2005)

*Lighter T-Jet armatures*

Let me be clear, I had meant to drill the armature laminations before winding the armature. This would serve to reduce the overall mass and allow the armature to rev up faster. I am just not sure how this would effect the magnetic filed that the armature generates. I know people have said that t takes the Quadrlam armature a while to get up to speed so I was thinking that it would help with that issue. Or maybe the three lamination from auto world or dash may be the ideal choice. Any feed back would be greatly appreciated.


----------



## rholmesr (Oct 8, 2010)

I am not an electrical engineer, just a dumb mechanical one. But i have some friends in the industry that have the right degree for this and have filled me in about as much as my brain can tolerate...

I have never rewound an arm but i have done a few thought experiments.

The steel in the lams can only tolerate so much magnetic flux (measured in lines per square inch of cross section). So lightening the lams this way- by drilling holes- could result in saturation of what is left, giving poorer performance and/or higher running temperature. Using higher quality steel for the lams, e.g. higher silicon content, would allow some reduction in lam area, all else being equal. If going this way i think i would go with making the poles skinnier rather than drilling holes thru them. Skinnier poles would allow you to get more turns of wire onto the winding for a given amount of wire, and more turns means more torque. It would be an interesting science project at least.

I do not know for sure but i would speculate that the lam steel in the old tjet arms is nowhere near the quality of that in newer ones like dash or even aw.

Smalltime mentioned a fairly simple method to reduce the o.d. And true the o.d. Just doing that should reduce the rotational inertia of the arm and make higher speeds possible. But at the same time, having larger gap to the magnets may mean that you need to use stronger magnets to get back to your original torque profile. When i work-up tjet arms for my fray builds i use a similar method to true the o.d.


----------



## smalltime (Jun 3, 2006)

> having larger gap to the magnets may mean that you need to use stronger magnets to get back to your original torque profile


Usually, when I true the O.D. of an arm, I'm trying to give it some coast. Some don't like a coasty car, some do. I prefer to roll the corners. 

But that's just me.


----------



## vaBcHRog (Feb 19, 2003)

You can also balance an arm by adding epoxy to the poles


----------



## dtomol (Mar 30, 2005)

*T-jet aramtures*

Their was an article in car model building a T-jet armatures using the lamination from a Mubuai D36. Tjet sig built a prototype but never fully tested it.


----------



## Rich Dumas (Sep 3, 2008)

If you reduce the mass of the laminations the motor will have less torque. With the motor free running it might spin up faster, but on the track the car is likely to be slow coming off the turns. My experience with armatures that have had the stacks turned is that the car might have a lot of top end but will not be so eager to get moving. It probably would not be legal to drill holes in the laminations, but if they were hidden by the windings no one would know they were there. If you are rewinding some arms you might as well experiment a little and report back on how you make out.
When I balance armatures I use epoxy on the light poles first and fine tune by notching the heavy poles.


----------



## rholmesr (Oct 8, 2010)

You can offset the loss of torque if need be by using stronger magnets. Standard tjets had pretty weak magnets in them. If the windings were designed for the weak magnets we could them presume that increasing the air gap by truing the od and using somewhat stronger magnets, e.g jl or dash, gets you back to the same ballpark in terms of air gap mag flux density. Or heck, maybe quite a bit higher - dash mags are way stronger than the original tjet ones. I have some pretty fast and punchy fray cars that are set up this way. It is all a very rich tapestry though... You can get a lot of punch just by having the pickup shoes set properly, which of course has nothing to do with the armature torque.

Toy cars can be a lot of fun cant they?


----------



## dtomol (Mar 30, 2005)

The Ultimate in HO power Armature for a T-jet
Would you believe an aurora Armature with Mabuchi D36 LAMINATIONS? 


Much has been said late on the subject of rewinding of Aurora Pancake Armatures I myself have done about the ultimate in modifications and I was begging to fancy myself as somewhat of expert on the subject. Then Richard Harrison came up with the idea for this new armature and showed me that I did not know anything. Basically the arm is a modified copy of a stock T-jet. The only difference (and it is a mighty important difference) is in the poles. The poles for are super modified hauler come from (are you ready?) A 1/24 36D Mabuchi! The Idea is to fit three laminations from 36D Mabuchi to a stock Aurora armature shaft to form the basic “rotor” everything else is about the arm is conventional, including the commentator and wiring. What are the advantages and disadvantages of the arm? Glad you asked as the former are myriad and there just aren’t
Any of the latter (unless you count the rewind heating). The arm is quite a bit lighter and has much better torque (due to the fact that it has more metal and more of it strategically located for the magnets to work on) than the stock Aurora Arm. Admittedly, the conversion takes affair amount of time, skill and special tool, but it is well worth it. These arms are the coming thing and mark my words, will power the 1968 HOCCI National Road racing unless the MINI Jet arrives in time and is as fast as it is rumored to be. One final word of caution: watch out for “kinks” in the wire when you are winding. If you get a kink , better start that particular pole over the wire will burn through at the kink when you shoot the volts to it and all your work will be for naught. 

1)	These are the basic materials an Aurora comm. An Aurora armature shaft and three 36-D wire epoxy, etc.


----------



## dtomol (Mar 30, 2005)

*T-jet Armature*

The listing below are for making a T-jet armature using Mabuchi 36D laminations for a custom armature. 
http://www.modelencyclopedia.com/magazines.php?MagId=49&PageNum=40
http://www.modelencyclopedia.com/magazines.php?MagId=49&PageNum=41


----------



## dtomol (Mar 30, 2005)

*T-jet style armatures*

For drag racing does anyone know what the ideal diameter of the armature should be? Everyone say to reduce the diameter but how much? Also which would be faster a 2 Lamination a 3 lamination or a 4 lamination armature with the same amount or number of turns of wire on the armatures.


----------



## slotking (May 27, 2008)

smaller diam will reduce torque(punch)
bigger diam will increase punch.

you can offset the above based on gearing

I am not a drag racer, but I would think it better to have the startup punch and increase the top end with gearing

JMHO


----------



## tjetsgrig (Nov 1, 2009)

Oh boy, do I have a ton to type on this subject! Saturation for one. There is a reason the quads run better ( see saturation explanation above ). No, I do not drill my blanks ( see saturation explanation above ). Quads have more mass which allow for more saturation and a larger, stronger magnetic field. No matter what I tried, I could NOT get the Mabuchi laminates to run as good as a quad, even building one hotter than a quad, just not enough mass for sufficient saturation. Ill take a quad over the custom Mabuchi any day of the week! Even quality of the steel makes a difference in performance, and I have HOURS & HOURS put into R&D!


----------



## dtomol (Mar 30, 2005)

*T-jet armature*

Have you tried building the auto world three lamination armature blank or the dash motorsports 3 laminations as a performance armature? just wondering where they fall in the mix.


----------



## Rich Dumas (Sep 3, 2008)

I had a few custom winds done by Daniel Cardinale on JL/AW three lamination blanks and they run well, but I don't know how they would have been if regular Aurora two lamination blank were used.


----------



## tjetsgrig (Nov 1, 2009)

Ive found that the Aurora 2 laminate makes a better performance motor than than the 3 laminate motors!


----------



## slotking (May 27, 2008)

we used to race both poly mag magnatractions and afx non-mags on road courses.

I used multiple custom arms from various vendors.
My arm of choice was the 3LAM arm from Kipps


----------



## alpink (Aug 22, 2010)

good to see Jim posting again.
I was starting to get worried.
I guess I should just drop in on him! 
LOL


----------



## dtomol (Mar 30, 2005)

I know Jim S said that the two lamination T jet armature blanks worked better than the JL 3 lamination armature blanks. I was wondering if he had tried The Dash 3 Lamination armature Blank? I believe that dash may use a better material for their armatures blanks.


----------



## oneredz (Jan 29, 2012)

dtomol said:


> I know Jim S said that the two lamination T jet armature blanks worked better than the JL 3 lamination armature blanks. I was wondering if he had tried The Dash 3 Lamination armature Blank? I believe that dash may use a better material for their armatures blanks.




Aurora probably used metal with a stronger magnetic attraction for their arm blanks than JL did. Don't know what Dash uses.


----------



## alpink (Aug 22, 2010)

it appears DASH is using the same blanks as AW/JL


----------



## slotking (May 27, 2008)

yep
they are the same from what I understand.

and yes, back in the day, higher ferrous content was little more common


----------

