3573 replies to this topic

[havlicek]

I'm looking for .007" arms to rewind. They can even be epoxied (I have a method for cleaning these) as long as they haven't been balanced...for example, the Mura Challenger I arms. C'mon...you know you have some somewhere in that pile of stuff you never use but have been saving! (Hi Barney ).

-john

[Victor Poulin]

I'm looking for .007" arms to rewind. They can even be epoxied (I have a method for cleaning these) as long as they haven't been balanced...for example, the Mura Challenger I arms. C'mon...you know you have some somewhere in that pile of stuff you never use but have been saving! (Hi Barney ).

-john

John,
I have a box of used arms that I paw through for ya, not sure if I have any, but if I do there yours.
Vic

[havlicek]

Hi Vic...THANK you. I have a fair supply of the .014" stuff, but the .007" ones are harder to come by.

-john

[Horsepower]

Weren't those two Certus arm blanks I sent .007? I THOUGHT they were but maybe I'm coocoo (MAYBE?). I didn't actually measure them, just went by the magazine adds.

[Alchemist]

I did my first and only rewind back in the late 1970's on an HO scale motor and I did it by "hand". Is it less effective to do a rewind by hand or is it necessary to acquire a "rewind wire tool jig counter"? Advantages/disadvantages to "hand winding" without the tool please? Am I confused??


Thank you.

Ernie

[Bill from NH]

Ernie, you can pound a nail in a piece of wood with a rock, but a hammer makes the pounding easier. Low tech, you could hold the arm in one hand, the wire spool in the other, & wind. To make things easier & the job go quicker, you can wind an arm using a pinvise (handpiece) to hold the arm while winding or else buy a crank winder like Rick's or one by LaGanke & others. In my opinion, you don't need a counter on the winder, only Dyna-Rewind sold winders with counters as far as I know. If you don't want to keep track of the number of turns as you go, measure out a length of wire & wind that length on each pole. In summary, it's not the tools that make the craftsmen, it's how they use the tools at their disposal.

[havlicek]

Weren't those two Certus arm blanks I sent .007? I THOUGHT they were but maybe I'm coocoo (MAYBE?). I didn't actually measure them, just went by the magazine adds

...sure thing Gary, but two arm blanks go awfully fast around here

I did my first and only rewind back in the late 1970's on an HO scale motor and I did it by "hand". Is it less effective to do a rewind by hand or is it necessary to acquire a "rewind wire tool jig counter"? Advantages/disadvantages to "hand winding" without the tool please? Am I confused??

Hi Ernie,

Besides what Bill said, your post brings up (sorta) the confusion some have regarding the term "hand winding". This doesn't mean holding the arm in your hand and winding, it means winding by any means other than a machine. I agree with Bill that a counter isn't really necessary, and have never seen a good reason to have one. However, winding using a clamp and crank (like the Rgeo LeKrank or the LaGanke or similar) versus holding the arm in your fingers or even in a pin vise (which is still far better than holding the arm in your hand) allows you to do a much neater wind and with more even/consistent tension on the wire. It's also a dandy way to hold the arm when making the com connections.

-john

[Prof. Fate]

Hi

Back in the 50s I did winds by clamping the lower poles in a simple bench vice and winding which also works.

Again, this is a technique done by 12 year old kids, how hard can it be?

Fate

[havlicek]

Having spoken about doing an example build based on easily obtainable modern C and D motors, I orderd a Mura Challenger I from Roger at MidAmerica, and the package came today. So let's see what you get for the $24
...hmmm, looks familiar for sure...maybe there's a bunch of similar-looking but cheapo substitutes in there. Time to open up the package and have a closer look:




Sure looks like a regular Mura C can (except for the eye-catching color of the endbell) Time to dig-in further:


Looks like a darn nice setup to me. Solid can (probably not the lightest around but who cares?), quality endbell with good hardware, springs, brushes etc. all fine and would be at home in about any buildup. What about those magnets though, surely those gotta go? Nope, they measure 1150 on my meter and are within a point or two of each other so, in this case, they're really well matched to boot! That arm has a pretty thick coating of epoxy on it; sounds like trouble. Better remove the com (carefully prying the tabs with a sharp X-Acto knife to free the wire and then twisting it off works fine) and put it in with the rest of my salvaged coms for use later on.


After removing the com and setting it aside, I'm faced with getting that heavy epoxy (check out the tail spacer area!) and magnet wire off the arm. Cutting it off with a Dremel is a difficult task that can damage the arm blank...there's gotta be a better way, and there is! Afterwards, you're left with a lovely .007" blank ready for prepping to wind. So for the $24, you get a great arm and a really nice/solid motor setup to stick it in afterwards. Since the magnets seem up to the task, this one will get a fat wire wind.


-john

[Alchemist]

Hi John,

You make it look sooooo easy!! I could get that far and then scratch my head asking - how does it go back together????! Without a meter to check the power of the magnets, is there another alternative to check magnet power?

Thanks for the breakdown John - it's really valuable info and greatly appreciated!!

Ernie

[havlicek]

Hi Ernie,

You make it look sooooo easy!! I could get that far and then scratch my head asking - how does it go back together????!

Aw go on, so far everything I've shown IS easy. Well, maybe except for getting the old epoxy and wire off there , that part used to be a real PITA and I damaged as many arms as I was able to salvage. I've got a better way now that doesn't damage anything, except for maybe a few brain cells

Without a meter to check the power of the magnets, is there another alternative to check magnet power?

Well, I don't even know that there was such a thing as commonly available gaussmeters in the 60's, I sure never saw one. People just kinda "felt" the magnets to see how hard they pulled thge arm into the can or how strong they felt when sticking a piece of steel in there. I mean, just knowing the make and type of magnets is pretty much enough. It won't tell you how well the magnets are matched, but that's really for racers and bigtime motor-builders. Us "regular folks" just want things to turn out OK. So in this case, we know that if you haver a set of magnets from a Mura Challenger I, they're probably good solid magnets. If you're doubtful about their strength, you can have them zapped.

Oops! I got the arm cooking in the EasyBake oven to cure the epoxy holding the com in place and the furnace cement insulation inside the stacks. It should be just about "medium rare" right about now! Be back in a little while.

-john

[havlicek]

The arm is now all ready for winding. I put a com on there and set it with epoxy, insulated the stacks with furnace cement (black goop) and baked it. After it came out of the oven, I gave it a quick polish just to clean things up a little and the arm still comes in at a bit over .512" diameter...poifekt (as Curley woulda said). Since this arm and motor aren't for anyone in particular (at least until someone asks), it's going to get either a #25 or #26 wind. I'll just throw caution to the wind



-john

[Horsepower]

Nice work! I mentioned that (the arms) because I'm thinking there might be a few more here, but wanted to make sure those were .007 laminations that I sent. I'll be checking tonight, later on in the evening.

[havlicek]

Hey thanks a heap Gary! Also, even if you don't find any more...I sure appreciate you even looking!

-john

[Bill from NH]

John, these Mura C-cans are some of the straightest ones that come from a factory. I straighten all my cans with the proper size mandrel & a metal working hommer. Often, I've had Mura cans that were the proper size & require no hammering. Yes, they are a bit heavy for competitive racing. None-the-less, you can still build some neat motors with them.

[slotbaker]

Well, maybe except for getting the old epoxy and wire off there , that part used to be a real PITA and I damaged as many arms as I was able to salvage. I've got a better way now that doesn't damage anything, except for maybe a few brain cells

Nice work.. Are you going to share the "better way" with us?
That's one of the things slowing me down.

Thanks for showing us all this stuff. It is totally awe inspiring.

[havlicek]

Hi Steve,

Nice work.. Are you going to share the "better way" with us?
That's one of the things slowing me down.

Sure thing Steve...I was waiting for someone to ask me that It's called methylene chloride or..."paint remover". I jave had good results with this stuff:

This stuff is nasty business and good care should be taken handling it...vapors and skin contact are a bummer. If you were to get some in your eyes, that would surely be something to remember. Anyway, it will not penetrate an arm fully in one application. What I do is put some in a film canister and then soak the arm (after I've removed the com since that's made of a form of resin also) for around a half hour. I take out the arm and rinse it well with soap and water. After that, you can usually remove some of the top windings on each pole. When it gets to the point where you think you might break the magnet wire...stop...soak the arm again and retry. Eventually, usually after three times, you should be able to get all the wire off there. The stuff turns the epoxy into a kind of "snotty" consistency and softens some of the underlying layers. It will also remove all or most of the arm's insulation underneath, so you wind up with a raw arm that needs re-insulating. I do a final cleanup with a wire wheel in the Dremel tool and the arm is ready to go.

Thanks for showing us all this stuff. It is totally awe inspiring

You're most welcome Steve, but thank YOU for looking. BTW, I hope that all this is just the opposite of awesome. It's my aim to show that not only can anyone do it, but that it's VERY enjoyable and satisfying. In this particular case, the inexpensive Mura C can Challenger I got from Roger is a GREAT motor to work on because it can almost be anything you want. There aren't any real roadblocks at all...can, magnets, endbell, hardware are all up to anything you want to throw at it. Sort of like the "small block Chevy" of slot car motors.

Hi Bill,

John, these Mura C-cans are some of the straightest ones that come from a factory. I straighten all my cans with the proper size mandrel & a metal working hommer. Often, I've had Mura cans that were the proper size & require no hammering. Yes, they are a bit heavy for competitive racing. None-the-less, you can still build some neat motors with them.

Thanks for the info Bill. I have to admit I'm awfully fond of these motors and hearing you say that only proves them to be even a better platform for working on. Truthfully, I only put the little thing about them being "heavy" in there because I've heard people say that. They seem like featherweights compared to older motors and if people were running a class limited to these things, I have no doubt that there would be some fast-as-heck racing!

-john

[Alchemist]

Hi John,

Thank you again for answering my questions.

It's appreciated!

Ernie

[havlicek]

Of course you're always welcome my friend. Now get winding...I wanna see a whole bunch of people tearing motors apart!

-john

[Alchemist]

I wanna see a whole bunch of people tearing motors apart!

As soon as I can sir!! LOL!!


John,


I have worked with paint stripper spanning over 30 years in the automotive restoration arena and can say I've stripped more than 100+ complete cars during this time frame. If I may offer you a suggestion please. As you're aware, Epoxies consist of two components that react with each other forming a hard, inert material. Part A consists of an epoxy resin and Part B is the epoxy crosslink or curing agent, sometimes called hardener. When "cured", the epoxy resin is highly resistant to "hot" chemicals like lacquer thinner - paint stripper=(PS). Which is why it will take a few or more PS applications to "breakthru" the surface before it starts to soften the resin.


Prior to soaking the arm, if I may suggest slicing the epoxy resin with a razor blade, as deep as possible, it will allow the PS to seep, penetrate and permeate the epoxy resin at its foundation, thus loosening the E-resin from its base thus decreasing the amount of PS applications required instead of trying to penetrate the "crosslinked" surface, layer by layer.


I have been able to remove 5 layers of paint from a panel with only one application of PS after I sanded/abraded the panel surface with 80# sandpaper and encapsulated the surface with a plastic sheet to retain the PS vapor. If you're wondering how I knew it was 5 layers of paint, I counted the different colors as I was scraping the paint off the panel.


Hope this helps.


Thank you.


Ernie

[havlicek]

Hi Ernie,

Prior to soaking the arm, if I may suggest slicing the epoxy resin with a razor blade, as deep as possible, it will allow the PS to seep, penetrate and permeate the epoxy resin at its foundation, thus loosening the E-resin from its base thus decreasing the amount of PS applications required instead of trying to penetrate the "crosslinked" surface, layer by layer.

Sounds reasonable Ernie except I don't know how much "slicing" I can do to the epoxy with a razor blade since what's on the arms is pretty hard and tough stuff. When epoxy resin cures, it acts more like one giant molecule than a polymer with a crosslinked surface. Me and resins go back a long way :-) Anyway, I will see if surface abrasion or scoring helps as long as I can do it without damaging the magnet wire, since the object is to unwind the arm...not to have to cut the wire off. Thanks for the idea

-john

[Alchemist]

Hi John,

You can always take some #180 grit or coarser sandpaper and break open the surface of the epoxy - that should help!

Ernie

[havlicek]

Hi Ernie,

I'll give it a shot and see if it speeds things up. It's not really much of a bother as it is, but anything that makes it quicker would be a plus. Let's face it, doing arms this way is never going to make economic sense anyway

-john

[Michael Rigsby]

John is right about those Challenger 1 motors, they are a good buy if you want to build up some practice motors to run in some "C" can classes. Some time ago I won a couple from Roger on Evil Pay, and dissassembled them and built up a couple of Gr12 wing car motors using ProSlot arms. The magnets in them are very strong Mura White Dots, and when expoxied in gave a perfect .530 airgap with no honing needed. As far as practice motors went, they were only a tic off from my Koford race motors and at a third of the cost. Those magnets are stronger than a set of ProSlot Mega III's, and though the case is a little heavier than modern stuff, it holds up well and the bushings are strong. They are certainly a good value for basing some building on and the hardware fits very well.

Michael Rigsby

[havlicek]

Absolutely Michael!

Some time ago I won a couple from Roger on Evil Pay, and dissassembled them and built up a couple of Gr12 wing car motors using ProSlot arms.

...and if you or anyone does that...PULEEEEZE send the stock arms to me. I know there's got to be a bunch of those arms floating around (I hope they weren't tossed ) and I sure can use them!

Of course, ordering this stuff from Roger @ MidAmerica is a no-brainer if you don't have a local track that carries them. You click on your mouse and the stuff appears as if by magic a couple of days later. No problemo.

-john