3573 replies to this topic

[havlicek]

Finished up the Mura Challenger I build. For the wind, I did a #26 that should provide LOTS of forward motion:


Reassembled the motor (the arm wound up almost perfectly centered in the field as it sat) with all the original parts. After all, the idea here is that the Challenger I is a great motor for building andyou don't really have to spend any more than the cost of the motor itself to wind up with a screamer. Gave it a quick spin a 6V and the phrase "dentist's drill on steroids" immediately came to mind These are great motors, and a great value as well.



In about any suitable chassis, this motor should be a real handful of fun. Next build will be a modern D motor for the same reasons...easy to get, inexpensive and lots of potential.

-john

[Robert V.]

Hi John
Nice work the arm looks great and i agree this motor should really scream way to powerful for a vintage style chassis maybe a champion Turbo flex and even with that it would be a real handful but it would be interesting to drive.

[Bill from NH]

It might be too powerful for a scale car, but an anglewinder chassis with brass pans & nosepiece from the 70s or 80s, similar to the retro-pros, ought to be okay. But you might need wings on the body.

[Michael Rigsby]

That would be a perfect Retro-Pro motor, or a good motor for someone wanting to restore and 80's era Group 20 and just want a motor to get it around the track without having to sacrifice a vintage Gr20 motor. Every time I've built a motor on one of those setups it is an absolute screamer, sometimes putting the modern stuff to shame.

That armature is gorgeous, John.

Michael Rigsby

[havlicek]

Hi guys. There are all kinds of ways to use a motor like this. One would be (as suggested) to use it as a substitute for an aging period motor. A version of a vintage pro AW chassis like many of those shown here by Rick T would be ideal. Something like this one would definitely work:


A wire perimeter chassis (very light) with a wing body would be excellent, and a real thrill to toss around. Something like this one (or even lighter like a tripod):


Any number of commercial G12 chassis would for sure work. There are lots of ways to go.

-john

[Alchemist]

Wow - nice John!!

Makes me want one! - But I already have a few from you that still need to be placed in a chassis!!! LOL!

[havlicek]

Hi Ernie and thanks!

I finished up an arm for one of Jairus' builds. This one is a #27 wind done on a vintage Mura .007 blank Jairus pulled from a B motor. Always a thrill to do one for Jairus because I know it will be going in a beautiful car!


...and back in it's setup, a Champion 16D:



Motor sounds great and doesn't seem to get overly warm. In any case, the Mura endbell and beefy hardware should provide it with all the prtotection it needs.

-john

[Alchemist]

Real nice John!!

Always a thrill to do one for Jairus because I know it will be going in a beautiful car!

I concur - I concur! It is always a visual delight to see Jairus's buildups, as well as your work on the motors John!!

Thanks again for taking the time to post the photos! I'm looking forward to seeing the car that Jairus will put this motor into!

Ernie

[havlicek]

I started on a Parma D motor, showing the steps involved with one of those and also that there are lots of options for modern and easy to obtain (as well as cheap) motors to rewind.

The subject here is a Parma D motor...plain jane and nothing special:



Taken apart, there's a perfectly nice arm in there with a long stack measuring .512" diameter. Magnets in this one measure only 825 or so, not nearly as stout as the newer ones but still fine. I may change those out with some other Parma magnets...we'll see.


I stripped the wire and tossed the fiber stack insulators, and also removed some lams bringing the stack length down to .500". That's still on the longish side, but should work fine for what I'm after here. After a quick cleanup with a wire brush in the Dremel tool, it looks like this:


Before I insulate the stack, I'm going to round or "ease" the edges of the stack top and bottom. If you look at the stack lams, you can clearly see that one end is already rounded somewhat and the other is sharp. This would seem to be from the process of stampong-out the lams from sheet steel. In any case, I take a small diamond point and round them over with the Dremel because these edges are a prime area where shorts can occur. Afterwards, the stack is pretty "safe", but the insulation is the real insurance against shorts.


Next, I brush on a nice coat of furnace cement as my insulator, making sure it's even and that those pesky sharp edges are well covered:


After baking the arm for 15 minutes to speed up the cure of the furnace cement, I give the arm it's first polishing to clean up the extra cement that got on the outside and smooth out the stack a little. It's still just over .510" which is my "target" and checking things on the RGEO balancer, the arm is fine...no "surprises after doing all the work to wind, tie and epoxy it



You can see that the furnace cement makes a pretty ideal insulator, and that porous surface is also great for absorbing a little of the epoxy when you finish the arm. That will greatly strengthen the cement and help prevent any that is exposed after winding from chipping off. I only have to set the com and the arm will be ready for winding. Of course the time already spent means that none of this is economically sensible, but these arms and motors aren't supposed to make sense...they're supposed to be fun.

-john

[Bill from NH]

This motor is looking good, John! I see you chose one of the older Parmas. In my opinion, the endbell hardware is better made than what's on their current 16D motors. And I like the over & under springs too, because they're steel & seem to retain their tension longer than the current brass/bronze ones. I built both my kids motors of this type when they raced flexis with me in the mid-90s. I still got a new one to build up for myself. These older Parma cans were/are a desired item by drag racers because the cans are thicker than the contemporary ones & thie magnetic field is supposedly better. Also my opinion, I don't know what wind you're planning to use, but I'd change out the stock magnets, regardless.

Who built the wing chassis pictured above with the RJR motor? It's an interesting design that caught my attention. Is it one of your builds?

[Jairus]

Soooo pretty!


Finally I get to say:
"MINE"!

[havlicek]

Hi Bill,

Yes, I chose an older one and from just looking at the two, I like the older one too even though I have some of both here. The arm that's in them is really nice too. I think I will change out the magnets as you suggest, even though what's in there is OK for milder stuff. They read about the same as some of the old magnets that came right after Mabuchi...like 825-ish, but the more modern D motor magnets read somewhere (if I remember correctly) around 1100 or so on my meter. That's a hefty upgrade and worth the swap for sure. I will keep the stock com even though there's room for better, just because I know they're OK for most stuff and I'm not going to make this a "stupid" motor...probably a #27 wind.

The wing chassis is mine and is sort of what I was building in the 80's, although I was doing a straight tripod that would have been a little lighter. I mostly put G20 motors in them and they ran great, fast and handled really well too.

-john

[havlicek]

Hi Jairus,

Glad you like it. It went out in today's mail so it should be there by the end of the week. I forgot to put a delivery confirmation on it, so here's hoping the PO is on their game

-john

[Alchemist]

Wow! Now I have a better understanding of "insulating the arm". The coating levels out real nice! Thanks for the tip about rounding the lam edges - makes a lot of sense to me now!

Thank you for the technical education along with the visual aid!

Ernie

[havlicek]

You're always welcome Ernie. The only thing is that the cement doesn't really level out at all. I only mention that because I know you know about wood finishes and finishes in general and that's a term (levelling) used in that sense. The cement really needs to be brushed out smoothly since, even after thinning it a very little, it still the consistency of say...ketchup. Still, it's the most economical and easy to use solution I've found.

-john

[Prof. Fate]

Hi

I apologize in advance in case I am repeating stuff you already know.

The "code" with the motors involving 16d involve the specs for the classes. 16ds use the long stack with the 7230 wind and is the 512. The "super 16d is a short 440 stack with the 28 wind. To make the tech easier and limit easy cheating, the arm is a bigger diameter, 518 if memory serves.

The risk is that the magnets are specific for the arms. Thinner mags for the "super" wind. Older packages don't always identify this aspect. With time, you get used to just seeing the difference in the package.

Fate

[Alchemist]

The only thing is that the cement doesn't really level out at all. I only mention that because I know you know about wood finishes and finishes in general and that's a term (levelling) used in that sense. The cement really needs to be brushed out smoothly since, even after thinning it a very little, it still the consistency of say...ketchup.

John,

You do an excellent job applying it to the armature because looking at your photo - it looks to have an even consistency to me; as though you sprayed it using an airbrush - real nice job!!!

When the coating is applied, is it applied for "coverage only" or do you require multiple coats to achieve a "minimum mil thickness" to ensure protection from electrical shorts; OR - does one coat application do it all?

I'm looking forward to seeing photos of each pole being wound and completed - PLEASE?! PLEASE?!

Thank you John!

Ernie

p.s. If I may ask please - how and what tool is employed to measure the air gap between the armature and magnets? Thank you!

[havlicek]

Hi Ernie,

When the coating is applied, is it applied for "coverage only" or do you require multiple coats to achieve a "minimum mil thickness" to ensure protection from electrical shorts; OR - does one coat application do it all?

One coat is enough, but you do have to go over each area a couple of times usually to get the stuff to not "separate" because of any oily residue on the arm.

I'm looking forward to seeing photos of each pole being wound and completed - PLEASE?! PLEASE?!

I have done that before here and even posted a video recently that shows some of this stuff. On this arm, it's already wound and just has to be finished-off, but I will do this again in the future.

p.s. If I may ask please - how and what tool is employed to measure the air gap between the armature and magnets? Thank you!

I use a caliper, but you can do simple go/no go "measurements" by just using slugs.

-john

[havlicek]

D motor arm is done. I used a Mura com at the last minute just because there's enough room in the stock endbell and I liked the way the length of the com worked. It's another 27 wind using the stock stack (shortened some) and shaft.



-john

[Alchemist]

I have done that before here and even posted a video recently that shows some of this stuff. On this arm, it's already wound and just has to be finished-off, but I will do this again in the future.

John,

My apologies for asking something you've already done - I'll do a more thorough search.

I admire your "engraving" on the arm - it looks so precise as though a machine performed the operation. I'm presuming the engraved numbers "3627" represent the number of winds and the wire gauge?

Thank you for your patience with my questions John!

[Champion 507]

John, what is the part number and who makes the bit you use to round off the end laminations? If I missed that in an earlier post, my apologies. I've been way too busy with other things lately. Sorry.

[havlicek]

Hi guys and yikes!, there is NO need to apologize.

My apologies for asking something you've already done - I'll do a more thorough search.

Don't worry about it Ernie, I only mentioned it because I thought that the info might be available for you already and I don't want to bore people by posting the same stuff over and over again. I will take photos of the whole "bad deed" being done on the next arm I wind

I'm presuming the engraved numbers "3627" represent the number of winds and the wire gauge?

Absolutely Ernie. That info is one there for me as much as anyone else because I tend to forget what I've done (I don't write this stuff down any more ) and like to get a feel for what winds with what arms work well.

John, what is the part number and who makes the bit you use to round off the end laminations? If I missed that in an earlier post, my apologies. I've been way too busy with other things lately. Sorry.

Hi Doug, I may never have posted that info...but PLEEZE don't apologize for asking...lemme go for a second and see if it's listed. Here's a picture of the bit...it's called a "Diamond Flame". If you only use it to cut hard materials like the steel of the stack ends, it won't load up and will last a loooooong time. I have a couple in different shapes and I mostly use the one pictured and it has seen a LOT of work without dulling or losing diamond abrasive. They cost only a few bucks.


Here's a link for one place that sells them:

Dremel Diamond Flame Bits

I also got some really nice diamond bits used in dental work by a member here that are great as well...some incredibly skinny for getting into impossibly tight spaces, but the above bit work exceptionally well for about everything.

-john

[havlicek]

I finished assembling the Parma D motor. I wound up using a pair of new Parma EPX magnets I had gotten from Scott at PCH (thanks Scott) a while back. The stock magnets in the older D can read a little over 800 on my meter, these come in at just over 1100...it was well worth the swap. The pair goes for $5.50, a no-brainer. While they are a bit thinner than the stock ones, I was able to shim them .007" and still use the clips that come with the magnets to make up for some of that...but there's no doubt they make a BIG difference performance wise. I could easily go to retainer springs by bevelling the edges of the magnets and shim them more, but as it stands, the motor runs cool and really kicks butt. The only other mod I did was to lose the stock spring posts and springs and go with Camen springs...much better as well. I agree with Bill, these old D motors are very nice. They have a "retro" vibe, and done up like this would be a nice substitute for to old stuff in any number of chassis/configurations.

There was some old solder on the can that I carefully removed, anbd then just to give it a little more of a "custom" look, I polished the can with Dico chromium (hard) polish. It sort of reminds me a little of a cross between the old Champion 517 and a Mura. It sure sounds right!



-john

[Alchemist]

Nice nice nice John!

Hypothetically speaking, in an inline configuration, if you left the armature shaft as is and mounted a pinion of the end of the shaft, would there be any concern with "runout"? Or, is the tolerance/clearance so small as no need for worry?

Thank you.

Ernie

[havlicek]

Hi Ernie,

The shaft is long because I set the arm up with just enough on the com end to ride on the endbell bearing fully. The extra on the can end will be cut off to length and that length is determined by the distance of the rear axle and motor set by the rear bracket (in an inline configuration). In the case of sidewinder or anglewinder, the shaft would be cut to fully seat the pinion. I usually leave the shaft long in any case so that the builder can determine exactly where to cut the shaft. In the rare case of a 4WD motor, I can leave lots of shaft on either end of the motor, but the long end going to the front axle should be supported by a bearing (or bushing) near the front crown gear to both minimize runout AND maintain a good gear mesh.

-john