38 replies to this topic

[SlotStox#53]

Have a very nice mint 707 can/arcos & endbell kit (Very BIG THANKS to a fellow Blogger ) sitting ready & waiting in the parts box & will be sourcing an armature blank and was wondering what wire & # of turns did the original 707 have?

 

Any possible thoughts on different winds #/turns that would be as fun & do the arcos justice and be reliable!?

 

Thanks

[Pablo]

This may be of some help:
http://www.slotcarta...mpion-707/page4

[havlicek]

Paul,

 

 

 

Any possible thoughts on different winds #/turns that would be as fun & do the arcos justice and be reliable!?

   

      Try #29 wire...how much?  That will somewhat depend on how neatly you tension and wrap the wire, but 65 turns should be fine, and the exact number of turns is MUCH less important than how you wind it.  Have plenty of wire on hand (it's fairly cheap) and start off by winding one pole over and over until you get things tight/neat/straight.  If it looks like a mess, don't worry because we've all been there many times.  Just unwrap the wire and try again and again until it at least looks OK.  As you're winding, make notes about how many turns on each layer and how you "turned around" to head in the other direction so you can duplicate as closely as possible the same patterns on the remaining poles.  Even if you wind up with a messy looking arm, it will still run fine if you don't have any problems with shorts and most ALL of those old Mabuchi arms (both stock and "custom" rewinds) were pretty darned sloppy anyway.   Be sure the clean the insulation off the wire ends before wrapping them around the com tabs, so that the soldered connection is as electrically sound as can be.  The insulation on modern wire is tough stuff and even a little left on the wire can result in resistance variances from pole-to-pole.  Use a good 60/40 or even a "silver" solder and never use acid core or acid flux on electrical connections.  If you must use something, a tiny bit of the old "Nokorode" applied with a toothpick is fine.  Use VERY little and don't get the flux on the actual com segment because the solder will instantly flow up onto them.

 

***If you have or can borrow a cheap multimeter that reads resistance ( ohms or symbolized by Ω ), check the arm BEFORE doing any epoxying.  You want to hold the probes on a pair of com segments at a time and get similar readings across all three pairs.  Don't worry if the readings aren't exact at this stage...just in the ballpark and use the lowest range setting on the meter.  As a final test before epoxying, touch one com segment and the shaft at the same time and you should get no reading at all.  If you do, you have a short.

***When you get everything above all set and want to do the "finishing", you can post here and I'll give you some tips about tying and epoxying, but spend a bunch of time on the actual winding.  Time spent now practicing will pay off bigtime later!

 

-john

[SlotStox#53]

Thanks for the link Pablo & Thanks John for the info !

[havlicek]

All good Paul.  As for "doing the Arcos justice", a #29 wind is good, but when you're all done, balancing will be important too.  If the arms runs well, it will likely spin significantly faster than stock.  The faster the arm runs, the more important balance becomes.  Vibration= wear on bushings/bearings=arcing at the com=faster wear= heat and burnt com.  It's an ever-accelerating death-spiral.  PLUS, the arm will never spin as fast unbalanced as it will when balanced.  The arm will get to the point in the rev range where it simply won't spin any faster no matter if you increase the voltage because the brushes will actually be floating on the com with a continuous arc between them and the com plates/segments.

 

Getting fairly good at static balancing is a whole other learning thing, but can really help.  For your best arms, it's cheap insurance to send them out for dynamic balancing.  Having the com cut (carefully, as the com plates aren't very thick on the Mabuchis) can also give you significantly better performance.  The whole enchilada is a delicate dance.

 

-john

[SlotStox#53]

Yeah certainly is the whole enchilada! Have done static balancing before of deathstar Parmas before with two razor blades in a block of balsa, certainly sounded and felt smoother.

Have upgraded to an RGeo arm balancer like the one you've got John so will practice lots. Although sending it out for dynamic balancing is the best.

[Gator Bob]

[havlicek]

I would be really careful about those recommended winds.  The 45-55 turns of #28 will be a hot wind (well...at least for an FT36D), but with taking care can be a reliable runner (I just did one 50T/#28, falling right into that range).  With the #27 wind, using the stock com and soldering the tabs, it's doubtful the arm will be reliable...unless it's just for a hot lap here or there!

 

-john

[SlotStox#53]

That certainly will be a HOT lap !!

Thanks for the picture Bob & thanks for the reliability/too hot to handle info John! Remember your advice on soldering comm tabs not being ultimately reliable past the #29 stage...

Will either give my starting skillz a go with mild winds on this & other arms, for a possible hotter 36d may see what your winding schedule is for something much more "Spicy"

[havlicek]

     I'm REALLY glad you're determined to give this a go Paul, and REALLY don't want to discourage anyone.  I think the best thing is to go a little slow and conservatively at first, because successes can be a great thing for motivating people to dig deeper.  I don't have any illusions that there will ever be a resurgence in interest in rewinding, or even for people outside the tippy top of wing, drag and scale racing just building motors.  Generally, racing specs have no place for this stuff anymore, and the disposable Chinese motors work well enough anyway.  However, plenty of people still build chassis, building...and even winding motors is easily as enjoyable!

 

-john

[Hworth08]

I was hoping someone might report the wind, or winds, used with the 707 motors. Those motors were ultra reliable.

Realize that 50 turns on the big stack was a fair amount more wire than a 16.

The mass of the big motors gave more material to expel heat also. Course that mass was their undoing.

[havlicek]

 

 

Realize that 50 turns on the big stack was a fair amount more wire than a 16.

The mass of the big motors gave more material to expel heat also. Course that mass was their undoing. 

 

Not that much, since on the smaller stack, you wind up with an additional layer.  

 

-john

[Don Weaver]

***If you have or can borrow a cheap multimeter that reads resistance ( ohms or symbolized by Ω ), check the arm BEFORE doing any epoxying.  You want to hold the probes on a pair of com segments at a time and get similar readings across all three pairs.  Don't worry if the readings aren't exact at this stage...just in the ballpark and use the lowest range setting on the meter.  As a final test before epoxying, touch one com segment and the shaft at the same time and you should get no reading at all.  If you do, you have a short.

 

 

 

Just a note: when testing for a short between the winding and the armature be sure to re-set the multimeter to the highest range (typically R x 1000 or higher). 

 

Don Weaver
 

[Gator Bob]

IMG_2063.JPG

 

So .... this does not really answer the question of  ..... & # of turns did the original 707 have.

 

From the "Factory"?

50 turns?

45 turns? 

Pot Luck?  

Cherry Picked - Junk?

Cherry Bomb - Runaway?  

 

BTW ..  if ya think about it.. Wind #1 on the backcard is a ..... ^{drum roll}.... Group15 arm  

[havlicek]

 

So .... this does not really answer the question of  ..... & # of turns did the original 707 have.

 

From the "Factory"?

50 turns?

45 turns? 

Pot Luck?  

Cherry Picked - Junk?

Cherry Bomb - Runaway?  

 

BTW ..  if ya think about it.. Wind #1 on the backcard is a ..... ^{drum roll}.... Group15 arm  

 

Not sure what you mean.  The image of of suggested winds...meaning for the home rewinder.  It's not about what the factory wind was, but I would bet Philippe or Steve O'Keefe of one of the other motor gurus knows!  Whatever it was, it was nothing particularly special anyway.

 

-john

[SlotStox#53]

John , I think Bob means the rear of the Champion card only shows the suggested rewinds, it doesn't answer part of the original question regarding what was the factory 707 wind

But thanks to the picture and the wealth of rewinding information from yourself I've got enough to be getting on with in selecting goodies to have a go at rewinding for this setup!

 

*Looks at spools of #29 / #30 magnet wire for purchase *    now I need a dang toaster oven to bake the arm in Also look into insulation coating for lams... Goes off and reviews all of your threads & posts about coatings.... The one 36D blank I'm looking at comes with the insulator that covers all of the webbing/and lam ends where the wire winds round plus kirkwood comm, think it's an actual Champion 707 as Doug *Mr Motorshop* posted about them very recently

 

One question John with all things epoxy I know you use the good stuff *Duralco* and how you can get away with hardware store goop for standard to mild winds but found this when looking at magnet wire.....would it be of any use? It says a fairly lengthy bake time for curing so didn't know if you could get away with a short bake time like you can with epoxy..

 

Insulating varnish

[Gator Bob]

John, that is my point,  what I'm goofing on is there is a range of turns for the home builder but I have not seen any documentation of the number of turns on the Champion factory RTR motors or carded Arms.

 

BTW: The #5 wind with 27 wire was sold as the 705 (for battery) in RTR motors and carded Arms.

[havlicek]

OK...gotcha Bob & Paul.

 

 

 

Also look into insulation coating for lams... Goes off and reviews all of your threads & posts about coatings.... 

 

There are a couple of ways to insulate the stack so the magnet wire doesn't short Paul.  First, look at the stack itself and imagine where the problems are most likely to occur.  #1 is the corner edges at the top and bottom that the wire has to bend over with each turn.  On many Mabuchi arms, the steel tail spacer has some sharp edges as well as those can easily cut through the wire's insulation and cause a short.  People often discarded the fiber stack insulators and/or removed lams from the Mabuchi arms when rewinding, but those stack insulators worked well at preventing shorts.  Some Champion arms had nylon "end caps" on the stacks which worked really well to prevent shorts, but took up a lot of precious real estate, making winding more difficult...I hated them and have thrown away a LOT of those darned things.

 

Short of powder coating, here's some things you can do:

1)If you have the fiber insulators, keep them because they work well.  Protecting those sharp metal stack corners takes care of 95% of your short problems.  You may want to center them perfectly over the lams so they protrude slightly on either side and put a tiny bit of CA glue on them to keep them from rotating while you wind.  On the smaller 16D stacks, you can trim the fiber insulators flush to the stack after gluing them in position if you need a bit more room to fit the wire on there...BUT...you'll have to be more careful about shorts.  This shouldn't be a problem on the larger 26D and 36D stacks.

 

2)If you decide to toss the insulators, take the smallest finest grinding point (the cheap diamond ones work really well) you have and slightly round off the edges on the stack.  This will more important on one end than the other, because the stamping process used to make the lams produces a sharp corner on one side and a rounded corner on the other.  If you look closely, you will clearly see and "fee" which side is which.  You can even remove the last lam (carefully without bending it) and flip it over, reinstalling it afterwards.  That way, both ends of the stack will have rounded edge lams.  Afterwards, you'll still need some sort of coating on the arm, and possibly the tail spacer if you use the sharp steel Mabuchi one.  Some arms came supplied with a black plastic spacer(s), those work well all by themselves and won't cause shorts.  You can brush on several coats of varnish or lacquer or some other type "paint", and even better would be some of the BBQ hi-temp stuff...it's sold in spray cans, but you can spray some  into a container and then use a fine artist's brush.  All of this effort will give you a slightly lighter arm with significantly more room to wind...but the arm can still short if it's a hot wind and the coating softens.   You would think that a good hi-temp epoxy ( some JB Weld is rated for pretty danged hi temperatures) would work, but the material so thick that it's impossible to get a thin and even enough coating on the arm to protect it and not make a mess.  You can use hardware store epoxy, but it can also run and "pile up" in the corners of the arm and is only good for around 250F, you'll get a neater and at least as temperature-resistant coating by simply brushing on a few coats of the right paint.

OK...*IF* you want to try powder coating, by far the most difficult [part is actually getting the "good stuff".  However, there are powder coat materials that will work on most arms and are easily available in small inexpensive amounts.  One I found (and I did a fair amount of looking) that works is a "matte" black EPOXY powder available from http://www.caswellpl...oating-8oz.html  The epoxy coatings are good for higher temps than the regular urethane and other similar coatings.  ***These are made for electrostatic coating using fairly expensive gun kits, which produces some overspray...BUT...they can also be applied using a fluid bed process.  You will have to experiment with different temperatures and membrane types to get the thinnest/most even coating, but you can search on YouTube to find out more about a fluid bed you can very-easily build yourself using a small aquarium air pump.  This powder has a cure schedule of 15 minutes at 375F and will produce a nice coating that's good for at least 100F more than typical hardware store epoxy.  ***Keep in mind that, if you do use powder coating, you'll have to clean the outside of the stack to get the material off of there.  You'll also have to protect the shaft from getting any powder on it and there's cheap hi-temp teflon tape you can use for that (also available from Caswell and others).

 

 

 

One question John with all things epoxy I know you use the good stuff *Duralco* and how you can get away with hardware store goop for standard to mild winds but found this when looking at magnet wire.....would it be of any use? It says a fairly lengthy bake time for curing so didn't know if you could get away with a short bake time like you can with epoxy..

 

Most all "Devcon" type epoxy sold now is only good to around 250F.  That can be fine for mild vintage rewinds, especially if the coils aren't that neat and therefor more subject to shifting around, but can easily fail on even moderate winds...forget about it altogether on the "hot stuff".  It seemed as though the epoxy available in the '60s was more durable (?).  If you use the Devcon type stuff, don't use the fast-setting type.  The regular slow-set stuff will give you more working time and is often a "little" better at resisting heat.  Apply just enough to cover the coils and then speed the cure by warming the arm at around 250F for 10-15 minutes.  Remove and check the arm every few minutes to be sure the epoxy hasn't run all over the place...flip it if necessary and/or remove some epoxy if it's still "wet" and NOT TACKY with a small square of paper towel.  An otherwise good arm can be ruined if not careful.  If done properly, a lot of the epoxy will "disappear" because before setting...it will thin out and penetrate the coils.

 

The particular varnish you linked to doesn't seem like it would be much...if any...better than regular epoxy and the epoxy will be a whole lot cheaper.  The stuff you linked to also doesn't have "armature coils" listed as a typical application, so it may not produce as mechanically sound a result on a spinning arm.

 

-john

[SlotStox#53]

Wondered about that varnish & saw the other applications & didn't think to look for armature coils being listed.

Remember you were at one point looking for varnish so was "oh let's see if this is the stuff John needs" ..

Thanks for all the insulating info , once I get going and dive deeper will look at the more expensive/involved products, the BBQ paint sounds a good place to start.

Got the wire sorted out, just need to purchase some later today once all acquired no armature will be safe

[havlicek]

You're welcome Paul...now my fingers are tired from all that typing!

 

-john

[Gator Bob]

Paul,

The original 707 blank has the molded plastic insulators and a LaGanke comm.

Even Mura used the LaGanke comm on 36D arms.

I had an NOS "Vulcan" EBD 36D Mura rewind but sold it on ebay years ago.   

[SlotStox#53]

Ah thanks Bob, have a LaGanke 36D hopup kit which includes one of their comms... looks a very well engineered piece!

I knew Mura rewound most motors , can only imagine what a Mura 36D would be lilke! Certainly have yet to see one appear on the 'Bay  

 

Jump in the WAYBACK machine Bob & grab that arm, sounds a rare beast indeed .

[Hworth08]

Paul,

I'm not sure Mura ever wound 36D motors. French might have been the first "company" to sell rewinds nationwide as his first generation (Russkit 22 painted white) are a fairly common find along with white over-painted 36Ds. Lenz wound 36Ds that were Russkits painted metallic blue.

If Mura did wind some 36s they would most likely be painted metallic lime green.

[Gator Bob]

 Don, I didn't have the motor just the arm sold separately in one of those plastic jewelry boxes.

 

The name Mura gave it was the "Vulcan" or "Vulcan II" ... guess it was a rare item. Maybe Scott bought it ?

 

I don't know if Mura sold RTR 36D Vulcan motors but if they had the custom arms they probably did.

 

I have pics on my back-up hard drive but can't get this new computer to connect to it to get them. 

[SlotStox#53]

Thanks Don , now knowing how Lenz & French did things it explains why seeing some old French & Lenz motors you often see the Russkit gold paint underneath!!