70 replies to this topic

[Geary Carrier]

A bit cleaner, switching directions from left to right is interesting to say the least...

 

[havlicek]

Nice!

[olescratch]

Looking good the first time to me, even better now.

[Geary Carrier]

This is the initial mockup of the oilite bearing with retainer to the end bell, alignment will be finalized with the magnets installed.

 

Just ran an end mill through the original bearing center line.

 

You can see the big difference in size from the original bearing.

 

 

[Geary Carrier]

Finally got the three poles wound and now on to the brazing business. This was wound with a continuous piece of wire for the second and third poles after the initial pole was wound as it was easier to do so at this point in time, (laziness).

 

Following John's nomenclature, I believe this is a 25/22 (6 and 1 behind). Which means (I think) 22 turns of #25, 6 turns on the first layer with 1 reinforcing turn back at the shaft.

 

[havlicek]

Looks great Geary.  22T of #25 should haul the beans alright.  One thing though, it sure looks as though the wires haven't been stripped where they pass over/around the com tabs.  If this is the case, the insulation is going to cause problems, even with the heat of brazing.  The heat will turn the insulation basically into carbon and other burnt stuff which will make the conductance of each coil wildly different.  Even so, the arm looks right there!

PS, there's nothing wrong at all with using a single piece of wire if you can still use the same wind patterns on each pole.  In fact, it just might be a stronger way to have at this.  On many winds, the wire hanging down off the com tab can cause difficulty getting the same number of turns on the first layer because of the slight offset it can cause.

[olescratch]

Looking good.  If nothing else, you're giving it a damn good try.  BTW, I think the normal/common method in stating the wind puts the number of turns before the size of the wire.  So you're 25/22 would be 22/25, making it more like others (just my .02%)! 

[Geary Carrier]

Thanks guys...

[havlicek]

There's an old thing about the magnet wire Geary.  Some of the earliest stuff could be soldered without stripping the insulation first.  I was told way back then not to do that, because even though it might work, the motor wouldn't run as well.  The modern wire's insulation is MUCH tougher, and even the higher heat of brazing will leave a carbon residue between the wire and the com tab it sits on.  Anyway, the arm DOES look great, and it would have been a shame to have got this far and have it not run well!

[Samiam]

Geary,

The arm looks great. Neat winds.

 

As John said, you've gone this far. Might as well try to strip the wires before brazing. Can you slip them off the tabs and carefully strip off the insulation?

[zipper]

Beginning 1970's the hi-temp polythermalese wires did need scratching, I tried to burn with a lighter and the result wasn't too good needing sanding/scraping still. The earlier ML or Belden wires were easier to handle.

[Geary Carrier]

Gentlemen,

 

 

There's an old thing about the magnet wire Geary.  Some of the earliest stuff could be soldered without stripping the insulation first.  I was told way back then not to do that, because even though it might work, the motor wouldn't run as well.  The modern wire's insulation is MUCH tougher, and even the higher heat of brazing will leave a carbon residue between the wire and the com tab it sits on.  Anyway, the arm DOES look great, and it would have been a shame to have got this far and have it not run well!

 

John, I will strip the wire insulation first before brazing, I was just excited that the winding went fairly well and showed pictures of the initial winding results. I appreciate your concern and comments.

 

 

The arm looks great. Neat winds.

 

As John said, you've gone this far. Might as well try to strip the wires before brazing. Can you slip them off the tabs and carefully strip off the insulation?

 

Sam, as this was the first armature I was not exactly sure when and how the wire would be stripped but it will be stripped and we will see how the brazing goes.

 

 

Thanks,

g

[Geary Carrier]

Got the brazing finished. Kevlar and epoxy is up next.

 

[olescratch]

What did you do to remove the insulation from the wires?  It seems to have worked, welds look good.  Can you show your welding set-up, equipment?

[Geary Carrier]

 

What did you do to remove the insulation from the wires?  It seems to have worked, welds look good.  Can you show your welding set-up, equipment?

John, I just cut the wrapped wires on the comm tab from the bottom side of the tab and removed them, then scraped off the enamel coating with the back of an x-acto blade.

 

I don't have pictures of the welding set-up yet but it is pretty much a copy of John Havlicek's.

 

 

Thanks,

g

[havlicek]

BOOM!  Nice job Geary.  Since I first started all this again, I've been trying to inspire folks to give it all a whirl.  As far as I can tell, you've gone further than anyone else I know of.  The wind looks great, the welds look great!

[SlotStox#53]

Looks the part! Great job

[havlicek]

This is exactly what you're looking for when brazing.  The joints should look like a good (low temp) solder joint, with good flow of the brazing metal.  The only difference here is that the poles should measure either dead-on or within a thousandth of an ohm or so.  If not, you go back, add a bit more silver (or the silver/flux paste) and hit the pole again with the heat.  That *usually* cures any resistance discrepancies PDQ.  The last thing that will cure a slight difference in resistance readings is, of course, to cut the com.  Getting rid of whatever burnt junk is one there brings everything into sharp focus.  

***So, you're looking for a good "mechanically sound" connection (ie: strong) as well as an "electrically sound" one (ie: as close to "perfect" conductivity as possible).  Silver alloy brazing alloys are excellent conductors, as good or better than the copper itself, but that itty bitty point where the copper magnet wire meets the copper com tabs can either make or break an otherwise good arm.  Geary's pictures tell the tale!

[Geary Carrier]

 

***So, you're looking for a good "mechanically sound" connection (ie: strong) as well as an "electrically sound" one (ie: as close to "perfect" conductivity as possible).  Silver alloy brazing alloys are excellent conductors, as good or better than the copper itself, but that itty bitty point where the copper magnet wire meets the copper com tabs can either make or break an otherwise good arm.  Geary's pictures tell the tale!

Hi John,

 

My initial brazing attempts were done this last summer and I was having problems with the, silver/flux paste, it wouldn't flow properly. Had the same problems this time so I used some low temp brazing flux and that seemed to work better. I still need to refine the fixturing and process but I'm reasonably close and I'm satisfied with the first armature to be brazed. I don't have a milliohm meter yet so I will need to get one or make an adapter for a standard ohm meter. I greatly appreciate you posting all your work on rewinding, I only made 10 mistakes instead of 100 mistakes...

 

 

Thanks,

g

[olescratch]

Just to see someone else stepping into the deep waters of motor building is an inspiration in itself.  Keep on posting your progress, we need it.  BTW, did you have any loud pops while welding, that seems to send me to look for something else to do in a hurry lol.  Thinking of putting on some headphones, tuning in some classic rock, and give it another try!  

[Geary Carrier]

 

Just to see someone else stepping into the deep waters of motor building is an inspiration in itself.  Keep on posting your progress, we need it.  BTW, did you have any loud pops while welding, that seems to send me to look for something else to do in a hurry lol.  Thinking of putting on some headphones, tuning in some classic rock, and give it another try!

John,

If everything is clean and you are making good contact with the ground and gouging rod tip to comm tab there should be no loud pops. I've had some pops and it was always something not being clean or making good contact and that equates to a high resistance that leads to a high current surge or pop.  I'm using 14 gauge Romex for wiring as a small current limiter and it seems to work if you slip as it doesn't vaporize tabs and wires.

 

Thanks,

g

[Geary Carrier]

Kevlar, epoxy tomorrow...

[havlicek]

 

 

I'm using 14 gauge Romex for wiring as a small current limiter and it seems to work if you slip as it doesn't vaporize tabs and wires.

 

One way to help prevent accidental arcs and destroying an arm is to use a power supply that can deliver enough current at very low voltage.  When I  was cobbling together my brazing setup, I went looking for power supplies that could deliver a lot of current at the lowest voltage and it got kray-zee.  The car-starter thing I landed on was the cheapest solution I could find, but no doubt it isn't ideal.  I don't know what the minimum current necessary for doing this stuff is (a variable supply and some testing would be great to get to some numbers), but from what web-surfing I did back then, it seems that the lowest possible voltage and enough current (*whatever that is) is what to aim for.

Mastech makes and sells a bunch of bench/lab type supplies for pretty cheap (*they even have a section for "slot car power supplies"!), and they might be a place to look.  I don't usually vaporize com tabs any more...but it took me a long while to get "pretty confident", and the possibility is always there

[wbugenis]

There are a lot of welders and diy welders out there because because they are being used to build e - bike batteries:

 

 

 

Geary, I have several used BK Precision 875B  meters like the one John uses if you need a meter.

You will need to make a little fixture like the one John has.

PM me if interested.

 

Great progress on the arms!!!

[olescratch]

OK!  Now I have another element to look at.  I haven't been cleaning the coms prior to winding, this may be my turning point.  I'm still gonna turn on some classic rock though, minus the headphones lol!