170 replies to this topic

[Pablo]

No problem frying your own work, it can be re-done. Endbells, unfortunately, often melt first. Just something to keep in mind...

[havlicek]

Endbells, unfortunately, often melt first. Just something to keep in mind...

... are you kidding me, that's the best part!

From my post above:

I also got a Parma D-can setup to use for testing out some of arms Ron is sending, never messed with one before. Can anyone tell me what's up with the weird springs on these things?

... anyone?

[Pablo]

OK John, I can sense you love to walk on the wild side Try 15 turns of 24 That should be a

On a serious note, since nobody responded to your question about "weird springs", I think we need a photo to understand the question.

[havlicek]

I'll try and get a photo up, but the brush springs are bent at 90 degrees where they would contact the brush. They run into the brush carriers... perpendicular to the comm instead of tangent to the com, as they would in a C-can or any other motor I've used???

I understand I've been away for a long time but... my how things have changed!

[Bill from NH]

John,

Sounds like you're using some stock 16D springs. The idea is for the end of the vee on the short leg to push the brush in toward the comm rather than to the sides of the brush hood.
Most people change to a quality aftermarket spring such as the Champion lights (red) which have conventional straight legs. Those 16D springs can be made to work but require a lot of tweeking. Sometimes clipping about 1/32" off the short leg helps.

[havlicek]

... Ahh, mystery solved!

Thanks, Bill.

[havlicek]

Rick... I got the winder and it's perfect, many thanks! This will make the process much more uniform and predictable. I drilled and tapped the bottom of the stem for a 10/24 screw and mounted it on a board so I can just clamp it to whatever surface I want:



Now I'm just waiting on the arms to get here.

[Pablo]

Holy mackeral, John, look at the size of that wire!

What are you rewinding, an alternator for a John Deere?

[havlicek]

That's nothing Pablo... I was thinking about dipping some #10 copper ground wire in lacquer. I figgered two or three turns would have been about right.

[Hworth08]

Nice-looking rewinding machine. Rick does very nice work!

The base, while nice, is WAY too big for my desk though, I'd take me a week to clean off a spot that size!

Something to watch for, check that the new comms will fit if using a vintage endbell. Trying to remember, seems maybe the Chinese comms mostly fit, the American arm comms I believe are too big unless you radius the Mabuchi endbells? If using vintage cans and bells, it's probably good to trial fit the whole setup before winding. Some of the new arms as per rules are a fair amount longer than the Mabuchi arms were.

[havlicek]

Thanks for the 4-11 Don... I've already run into that. I really didn't have much choice about the base since my vise is in the garage and it's already getting pretty c-c-cold here. ;-)

Ron... if you're looking in here, I got those arms... they will be a great help, much appreciated!

[havlicek]

I got my first one done yesterday as sort of a test to prove I'm on the right track and everything is working. The thing spins-up nicely... seems very strong in a stock D-can, although it could definitely benefit from some balancing and a proper setup. Biggest challenge (after cramming that wire on there!)... was getting the last comm tab soldered and tightened-up with two pieces of wire on it. I'm looking forward to trying this on a Mura C-can arm (whenever they get here?) since the comm is a little more generous.

BTW... the winder worked great and made this much easier for me... especially with such heavy wire (#24).

[Bill from NH]

John, do you recall how much timing you put on that arm?

[havlicek]

John, do you recall how much timing you put on that arm?

... sure Bill, I don't have one of those protractor timing-degrees thingies but the comm tab for the pole you're working on is lined-up with the leading edge of the next pole. Just eyeballing this, you should be within a couple of degrees of consistency if you use that as a guide. I got that from one of the helpful folks here that have contributed to this thread and it seems to work really well.

[havlicek]

I'm getting in the swing of things pretty well now and have finished a couple of "keeper" D arms. Here's one of my hand grenades:



I don't know yet how it will actually run, but it sounds pretty impressive anyway,

[Pablo]

Is that one balanced on the R-Geo, or are those just the original balancing holes?
The winds look nice!

[havlicek]

Hi Pablo,

I balanced it on razor blades; the arm was an unbalanced 16D I got from Ron. I made a block with slots for razor blades and spent some time trying/marking/drilling and it came out fine. The thing sounds like a dentist's drill on steroids and really dims the light on my homemade power supply , but these arms have very little room at the comm so I couldn't tie it up. I'm hoping that the heaviness of the wire itself will help keep it from flying apart??? Anyway, this stuff is really fun!

[Ron Hershman]

Looks like you're having fun now... great job.

[havlicek]

Thanks, Ron...

The arms you sent have been just the ticket for me to try to figure out what was going on here and to get my feet wet again. I'm still waiting on the blank C-can arms and comms from Mura to arrive (?), but in the meantime I've been able to re-learn some about winding and balancing.

The D can setups from Parma are... interesting. The air gap is large enough to drive a Jeep through, the springs make no sense at all (I tossed them as per suggestion here), and the design of the whole endbell (brush hoods, spring posts, etc.) probably could benefit greatly from insulating the springs and going with shunts. The magnets don't seem particularly muscular either, but I have no way of measuring that. All-in-all, I'm happy that these arms spin-up as well as they seem to and they'd probably do significantly better in a well set-up can with beefy magnets.

Right now... the arms seem to prefer heavier springs, but track-testing would be the real proof of that. I'm sure that ball bearings would also make a big difference over the oilites. Thanks again for the arms!

[Ron Hershman]

Yes, the D-can air gap is huge. China just uses a "shelf" magnet for this motor. There used to be thicker mags, but they were much weaker than the thinner ones.

The springs are again Chinese specials. Just brass and good enough to do the job for a "toy" motor. Use a good three or five coil spring with insulation and shunts and you will be fine.

The magnets in the D-can are quite strong and as strong as most C-can magnets. The C-can mags have more energy than the D-can mags, but the D-can mags are better than any '60s vintage magnet. Shimming the magnets to a tighter air gap will make the motor even run better.

[havlicek]

... As always, thanks for the info, Ron! I finished another one and went for the gusto this time... and this one really sings soprano (or whistles)! The ones I had done before this were a little mild, so I figured why not build a better bomb? :-) I also realized I probably made a mistake with the other arms by using 60/40 to solder the comm tabs, so I used silver solder this time and have gotten better at doing a neater job soldering those tiny-little tabs. :-)



I'm definitely thinking this one deserves to be treated right, so I want to set up the can. If anyone knows before I destroy a perfectly good can... are the magnets glued in on the Parma D-can... or are they just held in place by the metal "fingers" that seem to be crimped at the edge of the magnets? I'd like to remove them and shim them up, but they don't budge.

[Ron Hershman]

Which Parma can do you have??? The Deathstar or the Rotor can?

The magnets are held in the Parma Deathstar can by the two "shim" looking retainers on the top and bottom of the magnets.

Just sit the can on your bench with the oilite sticking up in the air and using a small screwdriver, a small hammer, and some light tapping and the magnets will slide down.

The Rotor can has the can fingers bent over holding the magnets in place. They may have put a bit of super glue on at the factory in China. Just soak the can in some acetone for a hour or two and then try tapping them out as above.

[havlicek]

It's a Rotor setup and I got the magnets out, but I did have to soak them as you suggested after prying the can fingers, although I couldn't see any residue in there from glue afterwards (?).

I did a little bit of a setup and put in a bearing in the can end of the motor, some better springs, and it really sounds nice! With this one... I'm afraid to let it wind all the way up, in a good way! Mura emailed me to say the C-can arms are on the way... perfect timing.

Thanks again for all your help.

[havlicek]

So after experimenting with both the long and short D-can arms (I forget what they are called)... with both #24 and #26 AWG wire, it looks like the #24 at either 15 or 16 turns is the way to go. I've been revving these things to full RPMs with no load for a while now and they seem to be holding up fine. No matter what recipe I try though... the #26 arms always seem a little milder for some reason (the electrical engineers in the house could probably explain why). A whole bunch of the first #24 arms I wound (mostly 18-19-20/24) were pretty tame also compared to the 15 or 16/24 ones.

Jairus... if you see this, I'll send you one of the newer ones to replace that "puppy-dog" I sent you. If you don't have any use for it, you can always use it for a sinker.

[Prof. Fate]

Hi John,

"Screaming" isn't the issue. For "scream", you could try 12/22!

But on the track, depending on the track and car, you will likely find that your "screamer" isn't the hot motor.

Fate