3573 replies to this topic

[havlicek]

Hi Ed,

Thanks for the report. I'd say 300 laps is a pretty good test if the motor is only running a bit warm. Considering how mild even the "B" motor is, I worried that even the new motor would still be considered "too much". I have to say again that these SCX motors are a great value and have lots of potential for "tweaking"...like a little Mabuchi Not bad for a $10-$12 motor eh?

-john

[havlicek]

I haven't done one of these for a while...it was time

-New Mura .007" blank/com
-#24 awg
-22 degrees advance
-.509" Diameter
-1.16" overall length (sized for vintage Mura setup)
-.2 ohm



-john

[Champion 507]

SWEET!!!
That ought to get an anglewinder around the track at a RAPID rate of speed.

Another first class build from the H-meister

What kind of mags are going to be installed, Mura?

[havlicek]

Hi Doug,


Thanks, yeah...it should dim the lights some On the magnets, I have several options, a few of which are Mura in different lengths and I guess types. I may have to experiment a little to see what works best for the setup. I still have to radius-out the inside of the brush carriers some more as the com is too fat for the original setup. I have it clearing right now since the arm spins freely, but it's awfully tight...so tight that it looks like it's hitting. Better to be safe than sorry! I also have to do away with the bottom leadwire tab and rig some sort of bussbar to get it up top as I assume the motor will go anglewinder, although it would make one helluva inline thingie motor Thanks again David...I'm looking forward to the grand opening gala celebration for the Motor Shop too! (hint hint tease tease)

-john

[Prof. Fate]

Hi

If it is a 24, it should be reading lower than .2! Is this another case where we have different meters?

I am told that a local just bought that 220 Engleman in San Jose, so I might actually have a venue this winter to actually run these monsters! Lucky, if true.

Spray glue is my friend!

Fate

[havlicek]

Hi Rocky,

My meter flashes between .1 and .2 ohm on this particular arm. Since it only resolves to the tenth of an ohm, I assume that means it's somewhere between .1 and .2 ohm. When that happens, I just call it a .2 ohm arm (using the highest reading as my "value"). This arm is also a bit of an experiment as the Mura .007" blanks have a really thin web so there's at least one extra+ turn on there. The thinking being that the overall length of wire would be near the same as when wound on a vintage blank. This arm is 21/24 and I normally would do 19/24. I haven't spun the arm yet, but I want to see how much current this thing draws at 21/24.

-john

[havlicek]

This arm is 21/24 and I normally would do 19/24. I haven't spun the arm yet, but I want to see how much current this thing draws at 21/24.

...well I just answered my own question. I slapped a set of short Mura mags that came with this motor in there without checking their strength or zapping them. A drop of oil on each bearing and I didn't realize the power supply was already on 5V from having cut the com last night. The thing freakin' roared to life and scared the heck out of me...I almost dropped the motor. I was able to shut it down right away though. Anyway, I starts turning over at around 1/2 volt with no break-in and draws 4.25 amps up to 4 V and it runs super smooth. This was one of those motors though where I just didn't have the nerve to spin it any higher than 4 V...even with my eyes closed This motor needs the "full treatment" with ball bearings on both ends, shunts and bussbars...not to mention a really healthy set of magnets. I'm going to have to take this all in for a while and think about this thing, but I was thinking of doing it as a #23 and am sorta glad I didn't.

-john

[Slotgeezer]

...well I just answered my own question.
..... and I didn't realize the power supply was already on 5V from having cut the com last night. The thing freakin' roared to life and scared the heck out of me...I almost dropped the motor.

I'm sorry, John.... But I JUST couldn't resist...

I've done that so many times, it amazes me I HAVEN'T dropped a motor !!

But.... There's no greater thrill than bringing a newly-assembled C-can open motor "up to speed"....



Take care, buddy !!!


Jeff Easterly

[havlicek]

Yeah Jeff...I just hate it when I do that I agree though...there's nothing like the charge from spinning one up for the first time...especially a "24". Catch you later Jeff.

-john

[havlicek]

A little update, after a few minutes of break-in at 2V and then at 3V the arm draws around 4 amps, maybe a little under. I can run this arm at 3V for whatever length of time whithout it getting past "warm" so I think it's going to do reasonably well when running...for a "24". I may be able to get the current draw down, but right now it seems awfully strong and smooth.

-john

[Champion 507]

John,

Do you have a good set of old c-can cobalts? How about a nice set of late model quads?

[Prof. Fate]

Hi

I have dropped the motor a few times!

I think it ought to be illegal for you to have so much fun!

Anyway, in the day, we ran these type arms with blue dots, white dots and the like. But we expected to do a motor rebuild every race and only get a couple races out of the arm.

Fate

[havlicek]

Hi Rocky,

Yes, this IS a lot of fun

Hi Doug,

I don't have anything special lying around, probably only new Mura Red Dots as far as new magnets. I have to hunt around to see what vintage stuff is here. I wouldn't use cobalts though as it just wouldn't be "right" for this kind of motor. The shorty Muras that are in there are surprisingly strong, but I wonder how a full length set would improve things since this is a .460" stack ...or maybe make things heat up more.

-john

[Prof. Fate]

Hi

One of my famous abuses of a track was when the owner challenged me to build a cheater 16d that he couldn't catch. Involved small cobalts in the middle of a set of ceramics!

The problem I had in 73 with re-working salvaged cobalts into slot car motors was that I had to re-think everything I knew about motor set up. You really CAN over saturate a stack.

Fate

[havlicek]

I did another #27 wind. This one has a com salvaged from a Mura Gp20 arm (thanks Barney!). Sometimes I can get them off in one piece, sometimes not but welded coms are ALWAYS a PITA. In any case, I'm pretty sure this com won't blow up like the last one The arm blank was from an unknown source. When I get some stuff, I clean things up, salvage what I can and put them away as I did for this arm. Anyway, the shaft was reasonably straight and looking at the web, it seems to be from at least a fairly modern motor originally as there was more room in there than the really old stuff. As expected, 27 wire is a really nice way to go for these motors as the result is very strong sounding but draws a very reasonable amount of current, never getting past only warm.


Here's the arm in it's new home, a spiffy Hemi-Buchi. The magnets in this can are very nice and there's no need I can see to replace them. So far, all I've done is to replace the can bushing with a ball bearing, but there's LOTS more work to do on this little guy. For a while I've wanted to cut off the endbell where the bushing is and screw on a bearing retainer strap and ball bearing since the bushing is the weak link on the Tradeship endbell (which is otherwise really nice). I may just do that on this motor if I get really motivated as I haver a method of doing the deed worked out in my head that should (even with my limited tooling) maintain the centricity of the replacement bearing.


For now, the motor sounds really strong...but it's time to go back and finish off my arc-welder...er...Mura 24 wind


-john

[Pablo]

Looks like 5 turns of coathanger

[Horsepower]

John-How do you get those arms to shine like that? I polished mine with sandpaper and emory cloth but it just doesn't look that shiny.

[Jairus]

Pablo:

John: with a set of PS HEQ Magnets that puppy otta'scream!

[havlicek]

Hi Pablo...well, you're partly right. Just a few more turns Even if there's not much use for these motors, they're wonderful!

Gary,

The secret was passed to me by an old Czech rewinder who made me swear to secrecy on pain of death. I just use #320 sandpaper, checking top to bottom as I go to make sure things aren't getting lopsided I used to take them all the way to #600, but it makes a weird...too shiny surface that doesn't even take arm dye evenly. Of course, polishing has no positive effect on performance (it could do the opposite if you take off too much), but it can help identify bad arm shafts, but I really just do it because it looks cool

-john

[havlicek]

Hi Jairus,

It screams already and doesn't even get too warm. I must have messed up somewhere!?

-john

[Champion 507]

HAVLICEK QUOTE:

"It screams already and doesn't even get too warm. I must have messed up somewhere!?"

***************************

John, send it to me. I can "PHIX" that!

No seriously, 2 gems in the making. I'm anxious to see the finished products.

[Old pink can guy]

Looks like total prefection to me. WOW!!!!!!

[Champion 507]

John,

Are those late model Parma magnets in the Hitachi can? I see what looks like one of their current thin metal magnet retainers in the photo.

[havlicek]

Thanks for looking guys.

Ken,

The 21/24awg wind seems about right for the new Mura blank. I took a little bit of an educated guess because the web is so darned thin on these arms and when the wire gauge gets this fat...one turn more or less makes a huge difference...possibly the difference between a slug and a nuclear warhead. Because of that, it's really important to get the pattern exactly the same on each pole, a difficult thing to do with such heavy wire. So I do have to struggle a little more with the big wire arms. The other worry with these arms is that, because the crown is so darned thin, you have to be very careful when drilling the arm to balance it or...poof. I only go so far with a 1/16th bit and if the arm needs more, then I have to open the holes up with larger bits to create more of a "flat/wide" hole as would be produced using an endmill (which I don't have). Thanks again.

Doug,

No they're not, and the retainers are sort of similar but work differently. In fact, it was a real PITA reinstalling the magnets afterwards until I could figure out a method. The magnets seem(?) to be for this can as they have some milling on them that looks like it was done for the can. Other than that, I don't know anything about them but they're nice and strong on my meter even though they have very little cog-effect. Actually, that's why I checked them because turning the arm by hand in the setup, they felt a little wimpy. Anyway, the setup came from Roger at Mid America with the magnets and the Tradeship endbell. Thanks Doug.

-john

[Old pink can guy]

John I sent you a pm for you eye,s only please let me know if you get it! Need to speek with you. Keep up the great stuff I think the biggest stuff I wound was 28 beldon wire and I was only 13 or 14 years old with the la cranke what a pain to do and then have mom yell at me for bakeing it in her oven!!!! Please pm me if you got my pm thanks KB. Forgot then sent it to Thorp For a balance and come true.