3573 replies to this topic

[Alchemist]

Wow! That's another gorgeous piece John!

I want it - LOL!!!!

[havlicek]

Hi Ernie,

You have a motor "problem"...which means you're a man after my own heart After experimenting some with the "Strapnut" conversions of the Falcon motors, I've come to to conclusions that:

1)With the neodymium magnets, a #27 wind on a .300" stack is a great fit. A #26 or even a #25 will run great but you start to get on the other side of the performance vs longevity equation
2)With the older ceramic magnets, one step down might make sense...a #28 seems about right. I've done some #26 winds with the ceramics (as well as in SCX RX42 motors whose thing but strong ceramics make great platforms for this stuff) that were pretty killer but gearing and setup become much more important

This motor runs as strong as I could possibly hope for one of these type and still seem "reasonable". I'll still do some #26 winds and even hotter if people want them, but #27 seems the best balance with neos, the S7 can and a C can endbell. LOTS of performance for a very modest investment.

-john

[Alchemist]

Hi John,

I'll take note of that great info - thanks!

In your observation, when winding up a hot armature, is the SCX RX42B can as compared to the S7, F7, TSR cans, all comparable in performance when using the stock mags?

If one were to replicate a motor, are the F7, TSR, SCX cans as structurally sound as the S7 strapnut you just built? You had informed me about the high RPM Hawk motor can not having the same structurally integrity as the other cans I just mentioned.

Thanks for your time John!

[Kim Lander]

John,
I have been running my Strap-Nut in an old wire chassis that I had made for INT-15...geared it 11-37...runs like a bat outa hell. it seems to really like the lighter frames, they seem to wind out a little better with less weight. Keep up the good work, wil have a package headed your way soon as I get some better weather here, thought we were going to get a break after this nice weekend but it is suposed to rain next two days then another cold freeze coming through with temps in the 15 degree area, I told you to keep that junk up your way, we dont want it here in Ga....it is going to keep me from racing Jan. 22 down in Thomasville Ga. way too far to ride in the cold, the heater on my motorcycle doesnt work that good.
Kim

[Marty Stanley]

{snip}
the heater on my motorcycle doesnt work that good.
{snip}

Real motorcyclists don't need a heater!

Besides, the reason I wear gloves is to keep my hands from burning when I grab the pipes. I know they're always HOT! Helps to thaw out!

If you are intersted, just 2 weeks later, there is a race a little further away, in Holly Hill, Florida. It will be a blast!

Hope you can make it!

[havlicek]

Hi Ernie,

In your observation, when winding up a hot armature, is the SCX RX42B can as compared to the S7, F7, TSR cans, all comparable in performance when using the stock mags?

The SCX motor uses ceramic magnets that are quite thin (similar in size to the S7, F7, TSR magnets) but strong. The mini motors use neos which are stronger but more likely to be damaged from heat and I don't know if neos can even be zapped at all by typical magnet zappers once damaged. I like the ceramics a lot and because they can be easily zapped, I think they're as good a choice as the neos if they're relative strength is taken into account.

If one were to replicate a motor, are the F7, TSR, SCX cans as structurally sound as the S7 strapnut you just built? You had informed me about the high RPM Hawk motor can not having the same structurally integrity as the other cans I just mentioned.

The SCX can is a two piece welded can of similar construction to the Hawk motor. The SCX is made of thin, relatively soft steel that is fine as long as you leave it pretty stock and don't do much hacking-away at the metal. The TSR and similar motors are all one piece "drawn" cans and the metal is sturdy. They're also well-formed cans that seem to be pretty square and true right out of the box. For doing these kinds of hybrid/custom motors, I MUCH prefer the TSR type cans because of how small...strong and light they are and because you can cut them down to almost nothing and they still hold up. I know that the vintage people may shake their heads at this, but the TSR-type motors are GREAT platforms for hot-rodding. They're really wonderful value motors stock, providing pretty great performance for almost nothing cost-wise...but you can do some krazee-kool stuff with them...a Dremel tool, an RGEO winder and a C-can endbell. The SCX RX42 motor can go all the way to a #26 wind with a C can endbell as long as longevity isn't a consideration...but those stock ceramics are great with a #27 or a #28 single and the motor would live longer.

Hi Kim,

I have been running my Strap-Nut in an old wire chassis that I had made for INT-15...geared it 11-37...runs like a bat outa hell.

That sounds about perfect Kim and I'm really glad it's (as we say in NY) woikin' for you! That's the thing, with that kind of gearing, the car must have some pretty great top-end...but in such a light chassis it should also be able to take off PDQ. Yours is (if I remember correctly) a pretty hot one...close to what I'd call a full-race motor so..."use the force wisely Luke"! Thanks for the report!

-john

[Robert V.]

Hi John

That motor looks great i am shore it will have plenty of power, i to would like to know if neo magnets can be zapped because there are a lot of those cheap little motors around with them.

[Victor Poulin]

I did another Strapnut arm for the last setup I built with the Mura endbell and S7 can. This time a #27 wind on stack assembled from loose Mura .007 lams. Arm is .300" long x .509" diameter. I did static balancing on this one and it's extremely smooth and torquey with lots of RPMs. It doesn't seem to get at all hot after a short break-in and draws around 2.5 amps...a strong but reasonable wind that should go like the dickens.



-john

It looks great John ! It's gotta go like hell because it's sooooooo shiny

[havlicek]

Hi Robert,

Hi John

That motor looks great i am shore it will have plenty of power, i to would like to know if neo magnets can be zapped because there are a lot of those cheap little motors around with them.

Thanks It should be somewhere around G20 or maybe a little better which would be great for general running. It's my understanding that neodymium magnets need some pretty heavy-freakin'-duty industrial gear (and power) to zap them. Of course they "can" be zapped since the material is zapped in the first place. I have seen conflicting reports about zapping them, but I know my zapper won't do them and I have my doubts about the general home-zapper type gear. In any case, keeping the winds a little (not too mild) on the mild side will keep the heat down to help preserve the neos, and will result in a car with great torque and brakes. The exception would be a drag motor, since those don't get run long enough for heat to be an issue.

Hi Vic,

It looks great John ! It's gotta go like hell because it's sooooooo shiny

Yep...we all know that shiny is good for at least an additional 3-5,000 rpms This one isn't "that" shiny since it was already setup with a #24 arm. The "24" was just too much though and I could see that one lasting for a couple of laps before bad things happened.

-john

[Alchemist]

John/other members,

Pardon me please for asking, but I have no concept of balancing an armature. I searched here and was unable to find detailed info. If anyone knows of a link, please guide me to it.

- What is the methodology-theory when it comes to balancing an armature?

- Where do you / How do you know where to start to drill; top, middle or bottom of the pole?

- How far do you drill initially/thereafter? Do you / can you continue to drill the same spot - going a little deeper each time to remove more material? How do you know how many places to drill?

- How do you know when to stop drilling other than the obvious - oops?

- When do you know you're finished balancing a pole before you move onto another?

Thank you for your time.

Ernie

[havlicek]

Hi Ernie,

Static balancing is a pretty simple concept...although getting it "right" or as close to right as you can definitely takes a little work AND practice for to understand what you're seeing. Practice is important because when you start getting closer to balance, you have to start interpreting what you're seeing. Basically, you have a jig with two parallel bearing surfaces...these can be razor blades or gauge pins or whatever. The jig is set on a flat surface and is rough-levelled in both directions...front to back and left to right so that you can rest the arm shaft on the bearing surfaces without it just rolling off the jig.

Next, you start by rolling the arm across the bearing surfaces (I use razor blades) and look for a heavy side. This is usually apparent at the start and you'll either see the arm come to rest repeatedly on one side...or see it "accelerate" as it rolls past one side. You mark that side and drill the arm to remove material and therefore weight. You keep doing that until the first heavy side seems to no longer be a problem and proceed on to the next heavy side. As you remove weight from the second side, you may see that you need to go back and remove weight from the first side since it can once again be "heavy" compared to the second side. You keep doing this until the arm either rests on a different pole each time it stops...or it rolls evenly with no "speeding-up" when it rolls past any one pole.

You need to know ahead of time that the shaft is both straight AND round. Even drill blanks can be out of true (slightly bent) and steel rod may look "round" but actually have slight flatness or sides rather than a perfectly round outside. If you're making your own arms...it pays to have a supply of good straight and round shaft material, but either bent or not round shafts will give the appearance that the arm is out of balance when it's actually a shaft problem.

All the above applies to static "old fashioned" balancing and, with practice and good materials you can get results that are anywhere from "OK" to perfectly smooth running. After all, the proof is in the pudding and when an arm runs and you can't feel any vibrations (like the arm above!) that's "balanced" enough...even if it might still be slightly out of balance. Dynamic balancing will balance the arm both on each pole as well as along the arm's axis and is both more reliable and more accurate. This process is like the balancing done on automobile tires when they're done on a spin-balancer.

To answer some more of your questions:

- Where do you / How do you know where to start to drill; top, middle or bottom of the pole?

Since static balancing is only balancing the poles in one direction and relative to each other while the arm is balanced on razor blades...it doesn't matter where you start. As a matter of habit, I start on the stack nearest the com (top)

- How far do you drill initially/thereafter? Do you / can you continue to drill the same spot - going a little deeper each time to remove more material? How do you know how many places to drill?

You pretty much drill a little at a time trying not to remove too much material...it's easier to remove too little and then remove a little more than it is to correct for drilling too much. As for how many places to drill...you just keep drilling until you have the arm's poles balanced. You start to know ahead of time how ,much drilling you'll have to do when you first roll the arm across the blades. If it seems like the arm is going to need a lot of work, you leave space to be able to drill as many holes as you think you'll need. Sometimes you get an arm that doesn't even present an obviously heavy side and you can't static balance the arm (that happens more and more as you get better at winding and using good materials)...sometimes you get an arm that is so out you know you won't be able to balance it (usually a shaft problem). That happens less and less as you make sure that everything is good before you start winding.

- How do you know when to stop drilling other than the obvious - oops?

It helps a lot to know how thick the "strut" or winding leg of the arm is as well as the crown. Different blanks are different in all kinds of ways, if you are only guessing...you might only be able to tell by the "OOPS!". I make my deepest holes with no more than a 1/16" bit as that's pretty safe. I have some 3/64" and 1/32" cobalt bits, but drilling with them is a PITA. If I need to remove more material, I do shallower holes with wider bits.

- When do you know you're finished balancing a pole before you move onto another?

...when it no longer falls faster or you can't tell it's still heavy.

-john

[Alchemist]

Hi John,

What a tremendous help your information has provided. It is very much appreciated!!

Thank you very much for taking the time to explain!

Ernie

[havlicek]

...never a problem Ernie

-john

[Alchemist]

John,

One day I'll get a motor together properly. Still trying to figure out some stuff.

Thanks again!

Ernie

[havlicek]

Hi Ernie,

"the longest journey starts with but a single step"! You can do this stuff at any level you're comfortable with and have a blast. From just making sure factory motors are set up nicely (at least the ones that can be opened and/or tweaked), to machining parts if you have small milling capability. There are loads of modern and even vintage parts out there for not too big of an investment. All it takes is diving-in and wrecking some motors and practicing! From Mabuchis to Muras to Falcons and everything in between, there's hours of fun waiting to be had

-john

[havlicek]

So the weather killed work today and I've got the freakin' flu (the NY variety, not to be confused with the "regular flu")...so I did up another strapnut setup based on the S7 mini motor with the neo mags. After having done a bunch of these, they're getting prettty easy and "standardized", so the work goes fairly smoothly at this point. Can is shortened and opened up top and bottom, Mura C can endbell is trimmed to fit, can is drilled for the endbell mounting holes (the worst part for me),. neos epoxied-in, endbell hardware aligned. I even cleaned-up and prepped the stock arm...installing a new shaft, but I'm not sure I'll use this. Pictured with it's slightly older brother:



-john

[Alchemist]

No John don't - No! - don't stop - LOL!!!!

My name is Ernie and I'm a "motorholic" - LOL!!!! I gotta have another one - and another.

It's like drugs John!!! LOL!

Seriously, does exposing the edges of the magnet affect the "magnetic field" especially when placed on a stamped metal chassis?

Thank you.

Ernie

get well soon John!

[havlicek]

Hi Ernie...can you imagine what will happen when you make these things? You'd probably have a bazillion of them!

Seriously, does exposing the edges of the magnet affect the "magnetic field"

Sure it does. The magnets and the can act together to create the permanent field. These magnets are strong enough that it doesn't seem to be a problem and there's the added benefit of even less weight (from an already light motor) and more airflow. Is this all a net gain or loss on balance?... beats me, but these little guys look cool and wll fit in about any car 1/24 or even 1/32 scale.

especially when placed on a stamped metal chassis?

Well if the chassis is made from a magnetic material (steel) and there's enough chassis material...it probably interacts in some way, but the real Einsteins of slot racing would know best if it's even a factor (I doubt it but...)

-john

[havlicek]

Before there can be "Arm Winding", there needs to be "Arm Building" or "Arm Assembly":


Starting at the top (from left to right):
-choosing the lams and shaft as well as planning for the length of the stack and position of the stack on the shaft.
-pressing the lams onto the shaft (after chamfering the shaft end to make this part easier
-coating the inside of the stack with HT epoxy and baking so it all stays together
-clamping and into the easy bake oven until cured
-cutting tail and com spacers to center the arm in the field of whatever setup it will go into...leaving a little extra for spacers
-coating to protect against shorts and back into the oven

NOW it's ready for winding:


-john

[Alchemist]

Hi John,

And I was just going to ask what are some of the tools needed to get started rewinding - LOL!!!

What about that clamp/vise you had drilled a hole thru to help push in/out the armature rod - do you use that from time to time or just the press?

Thanks John!

Ernie

[havlicek]

Hi Ernie,

The clamp works OK, better than a vise...but the press is much better still. I took the ram off and drilled a slight indentation on the bottom of it as close to dead center as I could manage. I then drilled one side of the turret all the way through in line with the ram's "dent" so I can push shafts on or off or just slide them. You have much more control with the press and can exert much more pressure without bending the shafts. Once the stack is assembled, you can also flatten the lams by putting pressure on them and get a nice tight assembly. It's not a very good press, but it was cheap as heck...I think around $30 or even less.

-john

[havlicek]

...and another Strapnut done; this time a #26awg. A pretty good amoiunt of time in these things between cutting down the can and endbell, assembling and winding the arm and all that goes with that...but I've got a good handle on them now so it goes smoothly as well as a little faster. With all the "dead" mini motors out there, these projects are pretty easy to get parts for and even the stock arm can be re-used (with a better com), although this one uses salvaged Mura lams assembled into a .330" stack. With a good percentage of the parts easily-available and basically "free", there's a lot less worry about messing-up harder-to-find vintage stuff. Build a light piano-wire perimeter/tripod chassis and slap on a wing-car body and you got tons o' fun with a "casual runner".



-john

[Alchemist]

Nice - nice nice John!!

I filed off the "sealed" end of a Falcon 7 motor and removed the armature. It had burned up and for some reason I had a difficult time pulling the armature out. I lightly tapped it out and the bottom arm bushing popped out!?!?! I presume I will need to put a "ball bearing" bushing on it now. I finally picked up some "magnet clay" to pick out the metal filings. I also went over the entire can with "metal conditioning discs of different grits" to remove residual solder, scratches and the sticker. I'll need to figure out what endbell will work?!

By the way John - had you seen this article regarding an SCX motor armature swap? The second to last paragraph mentions this.

For those that wish to read the article, here's the link to the motor review: http://www.sfgate.co...8TA.DTL&object=

Here is a part of that article that mentions the swap:

Now, some slot car racers feel the SCX range is too slow. The "B" motors address these concerns; and the 20k Pro Speed brings things into the range of standard Fly and Scalextric motors. However, other fast motors, particularly as used by magnet racers, rev into the 30k range.

I just happened to have a Parma 16D with pink endbell, now out of production, midway between the Death Star and Super 16D. I swapped the 16D armature into the SCX RX-42 case (very easy to do), as it is a perfect fit. At 12 volts, after only a minute of running, the tach read 43,950 RPM. Next time you take your unlimited magnet missiles to a track with a long straight, try an SCX RX-Parma 16D!

[havlicek]

Hi Ernie,

I lightly tapped it out and the bottom arm bushing popped out!?!?! I presume I will need to put a "ball bearing" bushing on it now.

You should be able to pop the bushing right back in. Maybe there was some solder on the shaft that prevented the arm from slipping through the bushing. Anyway, if the bushing is worn/sloppy on the armature shaft, you should be able to just use a bushing as both bushings and bearings come in 5mm and 6mm outside diameters. If the hole is too big for a 5mm...just carefully ream it out (a little at a time from both the inside and the outside of the can) with a tapered reamer until a bushing fits in there snug.

I'll need to figure out what endbell will work?!

C-can endbells will work, but you have to take down the diameter of the endbell and keep things centered. It's a little bit of a bother, but gets easier after you've done a few. If you know someone handy with a lathe, a fixture could be made out of a bolt and some nuts/washers to turn the endbell down and that would be more accurate.

The link took me to a different article...BUT...I had seen the one you quoted quite a while back. The Parma 16D arm will work nicely as an upgrade, but you can go quite a bit further than that with an endbell swap and still have a reliable motor.

-john

[Prof. Fate]

Hi

Ya, I thought we had chatted about the RX motor from SCX. These are the direct descendants of the old Mabuchi 13uo motor of the 60s. The endbell is excellent by the old and new standards compared to either the FK motors or the old FT130uos. The only real limit is the ceramic magnets.

The hottest of the stock winds is a 34single. The Parma 16ds used to come in two flavors, a long .500 stack and a "replacement" 440 stack. The long stacks were and are terrible and inconsistent. 70 to 73 turns of 30 wire, often on the same arm! The replacement 440 arms were more consistent and 65/30 winds. But the Mura "wasp" and "contender" replacements with the same wind are even better still.

The can is excellent as well, strong and straight. I have been meaning to do a frankenmotor with cobalts and the like on the thing, but got distacted by the new cheap pro slot and JK mini motors.

Fate