339 replies to this topic

[sidejobjon]

_John,

_{This looks amazing, what did this OHM at? When i read how to wind start wire goes one pole & finish end goes differant pole. These look same i know you said there not, so whats the deal? Your picture is so clear maybe i would be able to understand.}

_{Thanks John}

[havlicek]

Hi John,

 

 

 

This looks amazing, what did this OHM at?

 

I only check for shorts at this stage, and can't read final resistance until the arm is finished.  The job-sequence I've settled on for these things makes it necessary for me to go in smaller steps than with a regular arm.  The arm in these pictures has been epoxied twice (once with the high-temp stuff to pot the coils, and once with JB Weld to secure the com to the top of the coils).  Next step would be to solder the tabs and then add one more teensy drop of epoxy to secure the wires to the bottom of the tabs.  After all that, I can then measure the arm's final resistance.

 

 

 

When i read how to wind start wire goes one pole & finish end goes differant pole. These look same i know you said there not, so whats the deal? Your picture is so clear maybe i would be able to understand.

 

Yes, the process is basically the same with these as with any other armature...with the added "thrills" resulting from such thin wire and such a small stack.  ***When I wind these, I start with some extra wire taped to the arm clamp and left dangling below.  The end of each "pole" has the end of that same piece of wire dangling below the other (finish) side of that pole.  Now you have a piece of wire dangling down from each side of the pole.  When you start the next pole, you also start with a piece of wire dangling below the pole, and that one will be right next to the "end-piece" of the previous pole.  So now there's two wires (the end piece from the first pole and the start piece from the second pole between the first and second pole) hanging at the start of the second pole.  As you finish each pole, you get the wires properly paired and wind up with three pairs (for a three pole armature) hanging below.  I keep the pairs secured to each other with a little piece of tape and I also put a really slight drop of CA glue (applied with a straight pin) between the poles to hold each pair while I continue winding.  In the end, it may look like the two wires are both coming from the same place *because I kept them in that orientation while working on them*, but they're not.

 

-john

[sidejobjon]

John,
I will say it again, I am into HO But with all the Masters on Slot blog ,I spend more time here, with all history here. I been reading & injoying your post drooling over your builds , I am now honored to have some of your amazing work in my collection . looks like you mastered this also in no time.
Thanks again for taking project on.
SJJ

[havlicek]

Hi John,

 

     Thanks very much.  It's easy to be good at what I do...because I only do one small thing  I have built a fair number of chassis and cars over the years, but they pale in comparison to what Rick, Steve, Jairus, Dennis and others show here regularly.  Anyway, the last three I sent you come much closer to where I'd like to see these things.  I'll be happy to do some more for you now that they're pretty consistent.  For now, run 'em and enjoy 'em!

 

-john

[havlicek]

One for the vintage crowd.  A Mabuchi 16D stack.  Tossed the stack insulators, powder coated, drill blank shaft, Kirkwood com, spaced for FT16D end bell drive (I have a nice can and some Arcos) and done up 55T/#29 with mild advance.  The wind comes in at a bit over .4 ohm...off to be balanced, and then to build the rest of the motor when she gets back.

 

 

-john

[havlicek]

Here's a copy of some epoxying tips I had sent to another Blogger who also uses Duralco 4461.  Getting the mix ratio to work by experimentation is important, but also the way you apply the stuff is just as important.  Long ago, I stopped just applying the stuff and continually flipping the arm until it stops running.  4461 is very viscous to start with (a good thing for full penetration of the coils!) and gets even more so when warmed (an even better thing IF you're careful).  For putting together small batches for an arm or so, syringes used for adhesives (wood, wallpaper etc.) work well:
 

I've gotten used to a ratio that works by using syringes used for wallpaper paste.  I use a small blob of resin about half the size of a dime (but thicker because of consistency) and add two drops (with a fine syringe) of hardener/catayst.  When you get close to the right mix, even arms that don't cure at first will still cure (most times) after repeated baking...but too much catalyst will cause the stuff to foam (instant garbage).

 

This type is good for the resin:

 

http://www.amazon.co...pd_sim_sbs_hi_8

 

There are ones with finer tips that are good for the cataylst.  You could even use "needle oilers" if you can find then unused.  Something like this would work:

 

http://www.amazon.co...s=glue syringes

The resin ones can be carefully used and reused (spilling can be a problem) and if you fill the resin syringe half way so there's room to operate the plunger, yolu can do a lot of arms with one syringe full.
 

The catalyst ones should be discarded as old catalyst kept out at room temp will spoil faster and old catalyst residue will contaminate the new stuff you just added if you add new cataylst over the old stuff (unless you clean the tube well first).  Avoid getting the catalyst on you as it's a strong oxidizer.  The uncatalyzed resin is fairly safe.

 

 

For applying the epoxy, here's a tip:
 

Remember also that the amount of resin you catalyze will also affect the cure.  Once catalyzed, the resin/catalyst mixture will generate heat which can speed the cure.  Doing a test by just mixing a small amount and not putting it on an arm won't "necessarily" give the same cure results as putting the epoxy on an arm.  A mix ratio that won't work on an arm, but left in a cup could cure much faster than a thin film on an arm because of the heat the resin gives off when curing.

 

A good way to get excellent flow and penetration of the coils is to preheat the arm a little so it's good and warm to the touch, and THEN add a small amount of resin to the bottom of the arm coils with a toothpick.  Because the resin is very viscous, and gets even more so when it's warmed up, you should see the resin penetrate the arm coils almost instantly.  Then flip the arm upright and add the resin to the tops of the coils and around the com tabs (carefully!) and a tiny bit on the sides of the coils, and gravity will let it penetrate and run down without running over the com.  Put the arm in the oven and check the bottom of it after a couple of minutes.  If you see excess at the bottom, you can wipe that off before it cures with a small square of paper towel (I cut them up to about 2 inches square and keep a stack of them handy on my table for stuff like this).  You'll quickly get used to how much epoxy will work without running out the bottom.  This is MUCH better than coating the arm and continually flipping it to prevent running and will penetrate the arm pretty much as well as the commercial arms that are done with a vacuum bag.  I've taken apart arms like this to see how well it works and have found epoxy all the way to the inside of the coils.

 

 

 

The above all pretty much applies to any epoxy resin, although the syringes aren't necessary for the 1:1 mix ratio hardware store stuff.  Also the stuff in the hardware store is a much thicker consistency so you can be a little less careful (only a little) avoiding runs...but it's not particularly good for potting arms in the first place.

 

-john

[havlicek]

...and on the epoxy itself, the bulk of it should be kept in a refigerator...cool and dark will GREATLY extend the life of the material.  I keep out only the small amount in the syringes, and keep the bulk (and my powder-coat epoxy as well) in a refirgerator.  The resin will last much longer than the catalyst which (as a strong oxidizer) can go bad quickly if not kept cool.  If you spend the beaucoup bucks to get the good stuff, it REALLY pays to protect it best as you can.  If you're using the hardware store stuff...who cares anyway?

 

-john

[SlotStox#53]

Thanks for posting the ins & outs of Epoxy coating a slot car armature John All the info at hand to understand how to do it....  Will make do with some hardware store stuff first to get the hang of it Rick T seems to have good success with the Devcon 2 Ton epoxy so will give that a go.

 

Btw that Mabuchi 16D arm looks mighty sweet John

[havlicek]

Hi Paul,

 

     Always glad to share.  The Devcon stuff is OK for mild arms, there's also a lacquer that is used for this stuff that's a very thin/viscous material that penetrates exceptionally well and is probably as good temperature-wise (up to 200-250F), but I don't know where to get the stuff, and the Devcon is easy to find.  The "regular" Devcon is better than the fast set type by a little in the temperature department, and the fast set stuff can set too fast!

 

-john

[havlicek]

Actually, there's some pretty cool looking stuff when you search under silicone impregnating varnish that's good up to almost 500F.  As always though, you gotta buy industrial quantities.

 

-john

[havlicek]

...and another one for the vintage guys.  This one is headed for the mighty Mura Green Can.  A #27 wind (a favorite of mine) done on a new blank I assembled with a vintage NOS com.  This one (33T/#27) comes in at .181Ω and, in a nice tight old Mura C should be tons o' fun!  First, it's going out for a very light grind ("skinning") and balancing.

 

 

-john

[SlotStox#53]

Beautiful arm John that is going to look sweet all buttoned up in a Green can ! Should go very sweetly too!

Reminds me I will have to finish that lovely minty fresh Green can with that sweet 25# arm you wound for me , all carefully under wraps waiting for a couple of Rod & Custom builds to be built , before I tackle it..

Gotta get some 6mm bb for it too, semi assembled and looking/feeling very powerful indeed

Keep up the great work John .

[havlicek]

Hi Paul and thanks very much!
 

 

 

Reminds me I will have to finish that lovely minty fresh Green can with that sweet 25# arm you wound for me , all carefully under wraps waiting for a couple of Rod & Custom builds to be built , before I tackle it..

 

For sure.  A Mura with a #25 is pretty "classic", and in the right chassis makes for a ballistic ride!  The arms in the "mid class" like the 27 are still very fast, but you don't have to "white knuckle" it so much.  Years ago, I screwed with slot cars a little during my second go-around (after having stopped in the '60's) and really enjoyed the old G20 motors.  I built several wire-only perimeter chassis for them...super light...and with a good high-downforce body, they were a total hoot to drive.  Those were later C-can motors (and of course, this arm could easily go into a modern C as well), but the idea is the same.  

 

Anyway, for the last of these three motors, I'll be doing my favorite "new" motor...the JK Hawk of course!  I like to think of them as sort of a "C-motor" for the masses.  At $15, they prove that there "could" be inexpensive/rebuildable C-motor racing because there's nothing in them that isn't just a scaled down C-motor.  I still don't quite understand why people (aside from what they're being sold) run D-motors when the smaller/lighter/more efficient C-motor is a much better candidate.  The JK Hawk takes that a step further, being smaller and lighter still.  Like the "C", there's loads of potential in the little Hawk to stuff much better arms in there, and I've been doing that since they came out.  VERY cool motor!

 

-john

[sidejobjon]

Lets see how John`s Havlicek first panckes "Photo 1" run. Now to get them in a Chassis.Need a spacer .300 not to make gear to tight."Photo 3"

To be continued

SJJ

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[sidejobjon]

OK some more steps. Motor press photo 4. Gear hole to large , i get a ball bearing smash with hammer photo 5. photo 6 all there on top plates.

 

OK getting there

SJJ

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[sidejobjon]

Other side of 3 top plates photo 8. Get a flat Chassis , some super II mags & La-Ganke brushes.

Come on you large scale guys remember all this.There are other treads that tell you what else to do, remember now they been working on these Pancakes-TJETS for 50 years now. Drum roll please.

SJJ

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[sidejobjon]

John Havlicek,

You are outstanding, Thats why you are the master. sweet sounding Motor & the Blue powder coat looks Cool as H#$@. No  wonder there was not enough room for your winds on one tread.

As far as photo 10 John gets a big 10.

[havlicek]

Hi John,

 

     First off...thanks for keeping me posted.  Many times I send motors out and never hear anything...like the went into a black hole or something.  In most cases, I'm not that curious anyway, but with motors like these that are so different from what I'm used to, I definitely wanted to know.  Anyway, I'm glad they worked out for you.  Maybe sometime I'll try some of those little square-can type motors.  I'll just have to make up a clamp, but this makes me want to dig in a little more...maybe.

 

-john

[havlicek]

     Here's one for all the rewinders out there ( both of you  , because I figure it's a good thing to share info...at least some of it anyway.   I sometimes set out on little quests to figure stuff out.  Recently, I got myself involved with seeing what could be done with an FT36D motor, and keeping the stock magnets, springs, endbell.  When I was a kid, keeping costs down was paramount, and I didn't spend much time looking at improved hardware, or even remember seeing much of it.  We'd usually tear a motor apart only when it was totally caput (later on when the "bug" really hit hard, we'd buy them and rip them open brand new).  Of course, you could get a little more by simply dewinding the arm a bit, but we always wanted more!

    So I went for a #28 wind on a full stack and, as always, you need to find the balance between not enough and too much wire.  Fitting it on such a huge honking stack isn't a problem of course although, for some reason it seemed back then as it was ALWAYS a problem, and jamming it on there with a popsickle stick or whatever was handy was de riguer.  After a couple of tries, I settled on 50T/#28.  I also used a Tradeship com as my one "upgrade" because I simply couldn't bear doing the work and pretty much guaranteeing the arm would grenade sooner than later.  ***One "problem" with this wind on the 36D arm is that, starting out at the com as always, the last wind ends up at the outside (odd number of layers instead of even) instead of back at the com or even part way.  You can just run the wire back to the com over the top of the coils, but that's a sloppy (and less mechanically sound) way to have at it.  It occurred to me several years ago, when the same sort of situation happened, that you could simply start winding at the outside of the stack towards the com instead of the "normal" way from the inside-out.  I don't know if this sort of thing could be easily done with winding machines, so it may even be a "hand-winding-only" sort of deal (???).  This does present  a couple of difficulties, but nothing insurmountable if you try it a few times, and it makes for a very tight coil once you master it...because you're starting from a "dead-end" at the back of the crown where the wire can't move, and working towards the com.  It's kind of a "mind-tweak" until you get things sorted...but it works really well indeed!  I only use this "special pattern" when necessary, but there are many ways to wrap wire around an arm blank.  Think outside the box!

    So here's the arm "wound backwards" with the Tradeship 36D com (I have a box of them in various advances...this one is the 22 degree one).  The eagle-eyed among you will notice the "giveaway" by how the wires wind up at the com tabs  Anyway, it's a very strong runner in the completely stock setup.  I forget exactly, but it meters somewhere around .350 ohms and draws about an amp at 6V...staying cool and spinning up with authority if you goose it to 12V.  

 

 

-john

[SlotStox#53]

Beautiful big block arm John! That came out really well
love the blue stack insulation coating . Nice to hear the standard setups can do rewinds justice so well.

Cool information for winding outside to inside , always handy to have more information! Noted down & stored for my voyage into rewinding....... Now if I can just finish a couple of cars its all systems go

[Dan Miller]

John,

 

Over the years I have made many armatures with an odd number of layers of wire. To lay the last turn over the top of the coils to terminate at the commutator is quite acceptable. Study many Open class armatures being made today, as well as some of today's wilder Scale armatures and you will notice this is a standard practice. Yes, you have to use your head when applying the technique. As well, you have to craft your winding pattern, number of turns and create a somewhat mechanical lock to be able to accomplish this with reasonable reliability in mind. How you lay the last turn is important.

 

The fastest armatures of today, from an RPM standpoint, are Scale armatures. These are operated with 7.5 - 1 gear ratios and use rather small diameter rear tires. They peak out higher than Open wing cars. Some of the most popular winds made for this form of racing are 18/24.5, 19/25 and 20/25.5 winds. All have the last turn laying down on the top of the coils, to run the wire to the commutator, from outside of the coils. 

 

The vast majority of Open class wing car armatures all show the same technique as well. Look at 16/24, 17/24.5 18/25 and 19/25 armatures used on King tracks. All will have that distinct, outside to inside, lay down method, on the top of the coils, to route the last turn toward the commutator tab.

 

As you state, it may look sloppy but it is absolutely necessary with some armature winds. At least with 75% of the armatures I wind.

 

Dan Miller

 

.

[havlicek]

Hi Dan,

 

     Thanks for chiming in!  Yes, I have seen a fair amount of arms terminated this way and even done a few myself.  What I did was simply cut the last end of the wire a bit long and then relax the last loop a bit so I could slip it underneath before heading "home" to the com.  It kind of forms a "lock" that way and if it's strong enough for those scale motors, I'm sure it's strong period!  Still, I like to go my own way and like how the coils come out.  I'm also not finishing the arm with the wire flopping around.  The one possible drawback I can see is that my method does the equivalent of slightly increasing the stack height.  It's ALWAYS good to hear from someone who's been there/done that as much...and as successfully as you have!  Not many (well...make that no one) are willing to share.

 

-john

[havlicek]

 

 

Beautiful big block arm John! That came out really well 
 love the blue stack insulation coating . Nice to hear the standard setups can do rewinds justice so well.

Cool information for winding outside to inside , always handy to have more information! Noted down & stored for my voyage into rewinding....... Now if I can just finish a couple of cars its all systems go   

 

Hi Paul and thanks again!

The blue powder coat is a Sol Epoxy product and it's excellent.  Honestly, what I like about it is that it's closer to the color of the coating on the old Mura arms.  It doesn't work as well as I'd like with the membrane I use in my powder coating fluid bed, and I'm not getting enough "lift".  That results in a thicker coating than I'd like...but it's fine for these arms.  The 3M product I have (thanks to a Blogger!) works really well in my system but comes out a brownish green color.  I also really like the contrast between the blue and the color of the wire.  It makes it easier to see what's going on as you wind... a BIG plus!

 

On the standard Mabuchi setups, it is a challenge to get them to work well and not disintegrate.  I don't care much for when people put modern brush hoods on them or even stick modern arms in them (in the case of the FT16D).  It's sort of like..."what's the point?, you may as well just run a modern motor if you want less difficulty!".  I've been guilty of doing "some" non-period-correct stuff, but really only as "what-if" type experiments most of the time.  By the time you get into the Mura C motors, you're pretty much into (still!) modern motor performance and design, so you can do a lot more crazy stuff...like run a #25 wind and have it actually work...for a while anyway!

Anyway, my main point here was to share the idea that there are all kinds of ways to skin this cat.  An armature is nothing more than three electromagnets firing in sequence within a permanent field.  How you make those three magnets and get the coils on there is open to all kinds of approaches.

 

-john

[havlicek]

I Figure it must be time again for a "step-by-step" rewind, hopefully a help for someone out there

 

I give you the ubiquitous "blue wire" Mabuchi 26D (the "poor man's race motor"):

 

Prying the tabs open to satisfy my voyeuristic tendencies, I find 75 turns of what seems like #30 wire and the not-very-stout Mabuchi com:

 

 

We can DEFINITELY do better than that mess, and after stripping...the thing looks better already!

 

First things first.  Toss that com (and those fiber stack insulators in this case...although they can work OK with a little tweaking) and substitute a NOS Kirkwood, carefully bending the tabs so they don't stick out that far.  Afterwards, cut new tail and com spacers, temporarily assemble the arm to be sure it can be centered in the field later on.  When it's all good, the spacers get tacked in place with a teensy drop of CA glue.  BTW, it can be a help with many wind patterns to use the same diameter spacer material at both the com and the arm tail:

 

 

Now, remove the com and mask off the shaft so no powder coat will get on it...because the stuff is impossible to get off:

 

A little preheating, a dip in the fluid bed, a little post-cure afterwards and you get a super hard, durable and very heat-resistant insulating coating that almost seems like a ceramic:

 

 

Then it's down to permanently setting the com (and dialing in any advance), although you can set the com after winding...and it's off to LaGanke Land:

 

After all this, the com tabs get soldered or in this case they got welded.  Of course, before epoxying, you also want to meter the arm to see that all is good (and it is!) Next time, finishing the arm and then onto building the motor!

 

-john

[slotbaker]

Love this stuff... Thanks for taking the time to do the step by step..