3573 replies to this topic

[GTPJoe]

John,

Thanks buddy, I'm gonna try that. Yours look beautiful.....

See ya!!

[havlicek]

Thanks Joe...I'm sure it will work just as well for you. The stuff is very EZ and also helps hide imperfections in the can.

Here's a Mura short that Edo sent me. He noted the mediocre performance (I guess this was a low-end motor for Mura), but it seems like the parts themselves are fine. There was a nice arm in there that wasn't balanced/epoxied/welded or soldered. The com is very nice and the magnets seem fairly strong. Can is a regular Mura 2-hole and while the endbell isn't a double-overhead job, it's a quality piece. I would prefer a longer stack, but it seemed to me that there was no reason things couldn't be spiced-up. I stripped and repainted the can, zapped the magnets, cleaned up the endbell hardware, aligned the brush hoods and wound a #28S that measures .2 ohm. It now draws somewhere around 1.5 + amps and sounds lovely.



...and all dressed-up for the prom:



-john

[Tex]

Cool! The paint almost looks like modern camoflage. Tre' rigu.... Tre rig.... VERY cool!

[havlicek]

Thanks Tex. Yeah, along with the dimpling the paint does, there's also a slight color difference between the high and low spots. I really like the way it looks on a motor and it also helps to hide things like can welds and seams a little. Best of all I like the hardness of the stuff. Seems like it should hold up pretty well. Now I just hope that Thingee Kingee guy likes it. He's used to some pretty "top-shelf" stuff ya know Now I want to see if Brian likes it as well since he's got a can of the stuff too.

-john

[havlicek]

I finished off the last motor project for a while (I have two more waiting for parts). This is a 26D Mabuchi (Cox?) that I had started a while ago and finally finished using some ideas I got along the way. First off was to replace those awful can bearings. I used a 1/8" axle bushing as a reducer for the LARGE can hole that remained after removing the bearing. I then drilled and then reamed that out to fit a proper bushing that had a nice snug fit on the arm shaft. A new Champion endbell was next as the existing one was in sorry shape. The can was in good shape and all I did was polish it up a little. Using a Tradeship 26D arm blank/com, I did another #28 S, just a tough hotter than I had done before. The com was one of the ones with a pretty high advance (the tabs were really close to the trailing com slot), so I backed that off a little to what I think is more reasonable. I added some post protectors, Arco magnets and shunted brushes to complete the package. The arm is about .3 ohm and draws around 1.4 amps, doesn't get too hot and sounds great. The 26Ds are a real PITA to work on because they're so short, so when I did the can bearing, I did whatever I could to give the arm some extra room back there. Also, the Champion endbell needed to be relieved a little to clear the com tabs. I also bent the tabs down a little when setting up the arm for winding knowing this would likely be a problem. Anyway, the motor was sent out, so now I can get back to my Choti build when I get some time.





-john

[Slotgeezer]

Great photos of the 26D arms, John....

I ran my share of Champion 601's way back when, in the F1/Indy open-wheel scratchbuilding classes we ran that mandated a "stock, unmodified Mabuchi motor"...

Now, an update on the H21T25 motor, from an earlier post...

I don't think people here on the "blog" realize that out here in Los Angeles, there is such a thing as "too much of a good thing"...

Example... I warmed-up that motor on the Buena Park Gearding King track, & everything looked Kosher, while turning 9-10 laps at reduced throttle.... No excessive heat, good speed, & everything was cool....

So, I decided to "go for the gusto"...



WOW! ... I turned a 4.184 on green lane, w/ NO problem... Car REALLY likes the speed level, no weird "twitching" or unusual handling characteristics... REALLY fun, driving it....

Then....

It slowed down, a bit.... & continued to slow down a bit, each lap... My 3rd-Eye controller didn't seem "weird", or anything else seem "different" than a few moments before, so I rolled the car to a stop in front of me, & took a look...



Bummer.... a carboned-up comm, & a VERY dark brush track....

Hmmmm .....

Yep, I should'a checked the switches, underneath the drivers panel...

All the battery banks were switchd "in", along w/ the bank w/ the charger....

Now, how many banks of batteries are on this track ....

SIX !!!

And.... How many batteries, per bank ???

FOUR !!!

That's right, you do the math... 24 - 8D Cat batteries, a power tap at EACH track junction, & a pair of 75-amp power supplies...

Next time, I'll check the switches, ya THINK ?????

I put some tape head cleaner on the comm, rolled the liquid around & watched the comm get cleaner, then switched the power supply bank "out", along w/ 3 other banks of batteries... So, I ran again on "just" 8 - 8D batteries, & no charger....

Car ran MUCH cooler, & although the brushes glazed-over, I figure I can skim-cut the comm, file the brushes, & run it next time on only one bank of batteries...

So, the motor runs great... I just need to put it on a restricted diet...

Thanks, John.... Further updates a bit later, as time permits.... Tryin' to work this week, after a month's medical leave, is really kickin' my *ss.... Getting older sure sucks, huh ??

Take care, everyone..... & good racing!


Jeff

[havlicek]

Thanks for the report Jeff..."less is more"

-john

[Justin]

Mura will sell arm blanks in either .007" or .014" lams, powder coated and assembled to whatever stack length and they seem fine although I have had some difficulties with shaft trueness and don't have any predictable way to true the shafts (although I have worked out some ways to get pretty much "there"). Mura will also sell their "Diamond Cut" coms which seem to be of very good quality to me. Even so, the Mura stuff is expensive and figuring the arm/com/HT epoxy/magnet wire and other doo-dads, the cost per arm comes out to near $20 just for the materials. It seems really odd that the manufacturers other than Mura won't sell the stuff (I've tried) as obviously the vast majority of people would rather buy complete arms over the counter.

if mura will sell blanks and comms do you have any part numbers? didn't see any listed in the catalog.

thank you,
Justin

[havlicek]

if mura will sell blanks and comms do you have any part numbers? didn't see any listed in the catalog.

Hi Justin,

On the Mura website's "Product B" page...scroll down and you'll see the commutators. They're listed as being sold in lots of 12 for $56, but my experience with Mura has been that they will pretty much sell you what you want and in the quantity you want. The arm blanks have never been listed, so just ask them to quote you and they will sell it to you. You have to tell them what stack length and whether you want .007" or .014" laminations. The arm blanks seem expensive, but then again Mura seems to be the only company that will sell them...doesn't make sense to me, but that's the way it is. Here's a link for you:

Mura Motors Product B Page

-john

[havlicek]

I did a Russkit "22" for a blogger friend, and I think it came out really nice. All the Tradeship goodies, a new can bearing, flattened and filled the magnet retainer tabs, drilled for button head can screws, D magnets etc. I did a #28 awg wind with mild advance after trying a 28 dbl at first (not smart!) that was ridiculous for this motor. This arm seems right "there" at about .3 - .4 ohm & 1.5 amps and is about as hot as I think makes sense.



-john

[Maximo]

That motor is a work of art!

Pure and simple...

-Maximo

[havlicek]

mucho thankaroonies Max I was pleased with this one myself and am hoping the recipient is also!

-john

[Champion 507]

John,

I've taken a number of Parma Deathstar arms that have run their course and unwound them and cleaned them up. Could you not do that and add a new Mura comm and have a usable arm? Granted they're not the quality of a Mura but they're a whole lot easier to come by and sometimes free! I've had racers hand me ones they no longer want and not charged me a penny!

After I've totally stripped everything off one, I barely open the jaws of my bench vise, insert one end of the shaft in the opening, taken a small hammer and tapped the shaft down through the stack to make an endbell drive arm out of the thing. Add your insulators or your "magic sauce" and a comm and you're ready to go. So far all the ones I've done like that have been good.

[havlicek]

Hi Doug,

I've taken a number of Parma Deathstar arms that have run their course and unwound them and cleaned them up. Could you not do that and add a new Mura comm and have a usable arm?

For sure, and I've been doing that since I first started rewinding again. Really, some of those arms are awfully nice and I've forgotten which is which, but some of them are even nicer (Parma, PS etc.). Since all the D can arms I've seen use .014" laminations, I often will use them in vintage rewinds with either a Kirkwood or a Tradeship com and they make very cool arms indeed. In fact, if anyone has a bunch with straight shafts, I'll wind up a couple for trade. I'll probably do this exact thing for this project:


It's a Mabuchi FT16D that I replaced the can bearing on and used a cut down current Mura thin can as a can-in-a-can magnet shim. There's a nice set of Blue Dots in there now (and the airgap is tighter than a clam's butt) just waiting for a healthy arm. While I have .007" blanks here, I think that a .014" blank would look better and probably perform about as well so I'll use a modern D can arm for a blank and rewind it with Tradeship com. I think it will really sing!

-john

[Justin]

Hi Justin,

On the Mura website's "Product B" page...scroll down and you'll see the commutators. They're listed as being sold in lots of 12 for $56, but my experience with Mura has been that they will pretty much sell you what you want and in the quantity you want. The arm blanks have never been listed, so just ask them to quote you and they will sell it to you. You have to tell them what stack length and whether you want .007" or .014" laminations. The arm blanks seem expensive, but then again Mura seems to be the only company that will sell them...doesn't make sense to me, but that's the way it is. Here's a link for you:

Mura Motors Product B Page

-john

John,

thanks, i will look into it. so your just buying from them direct then?

Justin

[havlicek]

Hi Justin,

Yes, I buy direct from them. Never had a problem at all.

-john

[havlicek]

The above Mabuchi FT16D complete with a #28S awg arm salvaged, rewound and topped off with a Tradeship com (the arm blank from a 16D per the above question).


-john

[Tex]

Dood! Look at those winds at the bottom of that stack. I LOVE to see wire lined up so cleanly on an armature. It's so... so... symetrical.

[havlicek]

Thanks Tex...sometimes I get lucky (er...at winding I mean)

-john

[Justin]

Hi Justin,

Yes, I buy direct from them. Never had a problem at all.

-john

thanks John

Justin

[havlicek]

...and for Justin (or anyone else), here's one fresh out of the oven done on a new Mura .007" blank and com. A zippy #26 awg with welded com tabs that was super easy to balance. I used a different #26 wire for this one that's supposed to be higher temperature rated than the other high temp wire. I have a feeling that the insulation is the same but a little thicker which would account for the darker color:



-john

[Tex]

MMmmmm..... more sweet neatness.

[havlicek]

OK Tex...so I got lucky twice in a row. BTW, this arm is scarey fast. I experimented with some different springs and got it down to around 2.5 amps set it up in this old Mura:


...yikes! I've been doing Mabuchis for a little while now and forgot what these things are like This thing needs shunted brushes and bearings (these bushings are a little sloppy) so it can breathe

-john

[wilbor56]

john; bill here from nj do you still wind arms would like to get my hands on one to try out and to get a first hand look at a good one as i am going to start trying some on my own. this should bring up a big white cloud in the basement. (where did i put that fire ext.)
if you like you can contact be via e mail at wilbor56@verizon.net or by phone 7326202036.
thank you
bill harris

ps.. i know this is a old post but i am a slow reader and new to slot blog so alot of catching up to do

[havlicek]

Hi Bill,

This isn't an old post...the thread started a while back, but my last post here was yesterday! Anyway, I would love to share whatever I can with someone else interested in winding as sometimes I feel a little like Don Quixote here As someone recently told me here...I AM persistent I have some arms that I did before I started welding the coms on the really hot ones that I have kept for reference. They will run like heck, but I don't know how long they'll last and you're welcome to one of those. It seems like they would be perfect for your needs. Just PM me if you want one.

-john