3573 replies to this topic

[havlicek]

Hi guys and thanks. I guess I jumped the gun some and was feeling a little peeved. After spending the time on the above long-winded post (it's a big subject), I was thinking Robert didn't bother to read it...my bad. I should also mention that the lack of willingness to share information (let alone parts and sources!) from the few people who probably actually DO know anything about all this, has been something that has bothered me from the beginning. Because of that, I'm particularly eager to share whatever information I have...it's kind of a small way I have of giving those folks a "noogie".

On a different note you stated your arm meters .484 ohms
now with you saying that I think I'm using my arm meter wrong.
I'm using a Kapriwa the arms meter and I gently press on the arm when I use it with hardly any force because I dont want to dint the com.
So I think I'll just let the arms just sit there on there own from now on .
Yeah big difference between a real nice looking well wrapped arm metering 484ohms to mine with me pressing on it getting 015ohms
but theres two big differences as well to concider you got the smaller wire and I use the bigger wire so my thoughts are still all over the shop

Well look at it this way Robert. A typical #25 wind on a long-ish stack (say for a Mura "Green" can setup) could probably meter anywhere from .15 to .2 of an ohm. This is a hot motor and probably "right there" compared to what the pros were running in those days. A eurosport #25 today on say a .300" stack might measure around .1 of an ohm ...I'm throwing out ballpark numbers off the top of my head here. .015 ohms is an order of magnitude less even than that, so I think there's something about the way you're contacting the com to get your readings. Also, and this is important with such low resistance values, it's best to carefully meter the arm after the com has been soldered (or welded) and cut. Just the oxidation of a clean but not freshly cut com can throw the readings off. So I test the arms as they're wound, just to see that there are no shorts and the resistance values are "in the ballpark" from pole to pole. Typically, the readings will get closer after welding and closer still after cutting the com. It's not uncommon to get identical readings down to the thousandth of an ohm on a finished arm if you're careful. The above #29 is within a thousandth on each pole, and that's good enough for sure. When you get an arm that meters that well and is close to "naturally balanced" (ie: almost balanced BEFORE balancing), it's most likely going to be a good one.

-john

[Coal Train]

Now I'm worryed , I get worryed when things go good lol
The arm has been sent to get balanced but this is what it is
It's a proslot slightly over .400 long .443 diameter arm that I stripped
With a brand new Bugenis com
13 turns of #23 AWG 105 degrees celcius with the new ( can't remember what it's called ) insulated wire
Wire was soldered with the low lead tin/silver solder by use of a pointed tipped 80w soldering iron
I cut the com then treated the arm with cryogenics
Then after about a half hour ( finished dinner ) I thought IDE meter some arms so I
Checked 3 arms one of them being the one that measured .015
When it comes back I will post a pick showing volts amps arm tester with the arm and it's reading
so you all can have a look and let me know if my technic is not right
IDE really like to know if I'm doing it wrong

[havlicek]

Hi Robert,

First off, now that you mentioned you did a 13/23...that should read really low...REALLY LOW. Second, and this is more important, you should get the same or close to the same reading on all three poles. If you get that same reading, then I guess the arm is just one hot tamale!? Third, if that thing stays together, you've really done well!

-john

[Coal Train]

Oh cool , yes they all read .015
I don't know how many times I've been told about how important each wind is so I made sure I didn't slack off
Ive checked the continuety and all good so yeah pretty excited about getting it back
It's going into a 12 segment neo motor.
Well I'll step aside now and over to you , just like everybody said I could sit here and read your stuff all day.

[havlicek]

That sounds like one screamin' drag motor!

Well I'll step aside now and over to you , just like everybody said I could sit here and read your stuff all day.

NOOOO! Please post-away as I haven't much more to add to my already way-too-wordy ramblings here.

______________________________________________________________________________________________________________________

I finished off a #30 doublewind for Motor #2 of the Mr. Frank memorial auction (a Hawk) and boy does that bad boy sing a sweet song. I'm thinking that with a pair of those narrowed brushes (I think from Mike Swiss???), it should run even better. Even a #31 double would probably be a great wind for the little bugger, a #30D is pretty deadly sounding.

-john

[One_Track_Mind]

I finished off a #30 doublewind for Motor #2 of the Mr. Frank memorial auction (a Hawk) and boy does that bad boy sing a sweet song.

-john

Not sure if I did Thank You! Or not John!
But again THANK YOU!

From time to time I stop by hear and read what your doing, and 'how it's done' even though I will openly admit, I may never wind a motor, it's still fascinates me as to how far you take this part of the hobby.
I'm truly blessed to have some custom hand wound motors in my collection from you, and there simply georgeous works of art.
You bring music to my ears in more ways then one!

Thanks for all you do! And do for others, your a good man John, and one that I'm proud to call my friend.

Kind Regards,
Brian

[Jairus]

hmmm...that was a long post that required some effort, with no affirmation from the questioner that it was even read (much less a "thanks"). Oh well, I hope someone at least bookmarks it for the next time someone asks.

-john

I read it, good info!

[havlicek]

Thanks guys, but I wasn't fishing for compliments (even though I'm not immune to liking them ) so much as I was wondering why I had posted such a long answer if it was never read by the questioner. Like I said...my bad!

-john

[Russ Crites]

How do you rewind a slot car armature? do you have pics? When you start at one com tab to which stack do you start with?

Thanks

[havlicek]

How do you rewind a slot car armature? do you have pics? When you start at one com tab to which stack do you start with?

Thanks

Yikes! There's around a 150,000 looks at 117 pages full of the info. I don't mean to sound less-than-accomodating, but it's a really large subject. I've posted all the info (probably several times over) with pics, but you'll have to sift through this thread to gather what you need. Maybe at some time in the future I'll do the "condensed version" step-by-step when I have the energy...again.

-john

[NSwanberg]

Star at the very beginning. It will be worth it.

[Jairus]

Worth it for who exactly? Google "armature winding" for a start. The info and power of the web are at your very fingertips.

[havlicek]

Yep on what Jairus said! I will (like I said) condense the whole thing into a step-by-step at some point, but I (and others too) have posted all the stuff right in this thread. I know it's a lot to sift through...but at least it's there for now.

-john

[Bill from NH]

John, do you still have the Photobucket video or slide show you made for your son's (science fair?) a couple years ago? If so, a link to it might be helpful to someone new to winding.

[havlicek]

Hi Bill,

Nope...don't even know where to find that. I will do the "thing-with-pictures" for anyone interested at some point. I just hope someone somewhere bookmarks it!

-john

[havlicek]

The next few posts will be a condensed "step-by-step" of rewinding. More in-depth information can be found by digging through the pages of this whole thread, but I hope these are a help being in one place together.

First off, you have to build an arm for whatever setup you'll be installing it in. This means putting together a stack by pressing the lams on a shaft, spacing the stack and com to roughly center the arm in the magnetic field (and give you clearance at the top and bottom of the stack for the com and the can), installing the com with whatever timing advance you plan on using and doing whatever you can to insulate the stack against shorts. Here I have a stack built out of .007" lams given to me by a Blogger that Bill Bugenis coated for me. I had previously installed a drill blank shaft and then after getting it back coated, installed one of Bill's coms. Here, the advance was kept to a mild 11-12 degrees since the motor is a tester with solid neo magnets, and I'm trying to keep the heat to a reasonable level. The can is from some Chinese motor sent to me and I installed a Hawk end bell and a can bearing:



Here's the arm blank as built for the setup. The arm will roughly center in the field and can be fine-tuned with spacers to get it "there":


...next up, I begin to wind.

-john

[havlicek]

For the demonstration, I'm doing a #28AWG wind and here's the arm mounted in my hand crank with the first pole done:



For this arm, I'm doing a conventional single wind (as opposed to a hemi, a star wind or one of my "secret" winds...and not a double or triple). Here's the arm after two poles:



Here's the arm after the third and final pole:



next up...welding the com connections.

-john

[havlicek]

After the arm has all been wound, it's time to make the com connections. For the vast majority of arms I do, I "weld" the connections (or "braze" or "hard solder") using jeweler's silver in the "Easy" alloy that flows at around 1200°F. That melting point is still comfortably below the melting point of the copper com but way above what the motor will ever experience. Silver is also about the best conductor there is (better than gold even) and the heating process guarantees that any tiny residue of insulation or oxidation is gone. The key is to get the com tab above the melting point of the silver reeeeeeally fast, and then to "get off" the tab ASAP so as not to damage the com. The com will be going through enough hell when the motor's running, it doesn't need any more abuse beforehand!

I use a 55 amp car starter connected to a footswitch at the positive clamp and then on to another clamp that holds a sharpened carbon rod. The negative terminal of the starter goes to a clamp I fashioned that fits the com. When you step on the footswitch, you complete the circuit and 55 amps will heat up that carbon rod (which is being held on the com tab by moi) PDQ to "yellow/white hot". I have some brazing flux and a small piece of very fine silver wire sitting on the tab and you can see the silver flow within about a second or so of stepping on the switch (sorry about the fuzzy picture):



When all three tabs are done, I give the whole com a quick cleanup so I can accurately test each pole for resistance. Instead of holding the meter's test probes by hand, I use a nifty jig Bill Bugenis gave me so you can just lay the arm on it, read the results and spin it pole-by-pole to get consecutive readings. This arm with it's #28 wind on a .340" long stack comes in at exacatackawacklly .221 ohms per pole. You want consistent readings from pole to pole and when they're all exactly the same to within the tolerances of a meter that can read fairly accurately down to the thousandth of an ohm, you should be good-to-go.



next up, tieing and epoxying.

-john

[havlicek]

...I forgot to mention that the insulation needs to be removed from the magnet wire at the places where it passes over the com tabs...this is really important. I use an X-Acto knife to carefully scrape it off without damaging the wire, others use a very small ball end diamond bur in a rotary tool (I prefer to scrape it off). Whatever method you use...be thorough and be careful with this step.

By the way, that the motor manufacturers charge what they do for either machine or hand wound arms never ceases to amaze me. Even setting up for production runs to keep costs low, the time, materials, R&D, tooling and effort involved to make slot car motors is significant to say the least. Without knowing the economics of it all, I feel confident that none of them are getting rich doing this stuff. People walk into a track and pick an arm or a motor off the shelf, and I wonder if they understand what a bargain they're getting. It's one thing to do this as a hobby...very interesting, challenging and fun, but to make a profit off this as a business must be torture! Hat's off to all the manufacturers...big and small!

-john

[Coal Train]

I'm loving this stuff John , this is fantastic.
I think I've been lucky with the arms I've wound lately except my last one.
Went to send it down the straight and it started to smoke badly , what have I or what could be the problem ?
Has this happened to anyone else ?
Rotation correct doesn't go backwards only thing is I didn't coat the stack before winding and pretty much through it on the track about
2 hours after bakeing.

[Marty N]

John, great work and I for one thank you.

[Coal Train]

A quick double check and I've found the problem .
It's a short. Oh well Do it again.

[Jairus]

Your winds are getting so clean John! Wow.

[havlicek]

Robert...sorry I didn't get a chance to try and answer...but GLAD you got it figured anyway. The stacks really need to be coated with something...or at least try and get your hands on some stack end insulators. Even if you manage to wind an arm that at first tests OK without some anti-short protection, it's only a matter of time before you get a short. The magnet wire can even short on the com and tail spacers...anywhere they kmight touch something conductive.

Marty...always glad to help

-john

[havlicek]

Your winds are getting so clean John! Wow.

Thanks buddy It depends on the wind and the stack somewhat. These .007" lams are really nice wherever they came from (I forget already!)...just a little more room inside makes things sooooo much easier than say the old Mura lams. I DO try and keep things neat though and, through working on arms for Bill Bugenis and shooting for certain patterns and the shape of the coils, I think I have managed to keep improving. Modern .007" lams are really tough to come by, so I tend to save them when I can get some, and these ones are really nice from a winding perspective.

-john