40 replies to this topic

[havlicek]

 

John, the motors I have are RS-360 style, I think?? I have not checked them or ground on them but I was planning to do so sooner or later. PM me if you want me to check them or send some or??.

 

dc

 

I have to dig through my "pile-o'-stuff" Dave, but I think I have some (the rest of the motor designation can be important as to the magnets) and will check them on my meter to see how much "oomph" they have.

 

-john

[Gator Bob]

Nice 'batch' for sure John !

 

On the center 28w  FT16D ... are there 3 insulators placed between the lams?

[havlicek]

Nice 'batch' for sure John !

 

On the center 28w  FT16D ... are there 3 insulators placed between the lams?

Thanks Bob, yes (from above):

 

 

 

In the middle is another FT16D, this time I segmented the stack into four sections with the fiber insulators I always throw away (it was tough finding some to screw around with). 

 

 

regarding the stack segments:
 

 

IIRC some rules required a minimum stack length.  Using spacers kept the length legal but used less iron, like today's short stack.

 

Don Weaver

 

That makes sense Don...at least from a slot car perspective, but I've seen these before in non-slot motors so *I think* there must be a specific performance characteristic that's desirable.   Beats me though!

 

-john

[CaptREDD]

Mr. John,

 

Have you tried skewing the lams on a slot car motor...model trains do it for smoothness and bottom-end torque....what comes to mind is one of those

5-pole large diameter arms with skewed lams...

 

REDD

[Hermit #1]

Have you tried skewing the lams on a slot car motor?

Back in the mid-1960's this was tried by a rewinder in central Florida who called his motors (mostly 36Ds) Vaughn-McCauley Whistlers. 

They definitely made a whistling sound when run, and had smooth power when accelerating - but I never saw any increased bottom end torque from them.  I tried a few that way with my own rewinds, but never found any significant advantage.

Slanting the laminations is going to make the winds longer relative to a straight stack (same # of turns) - increasing resistance slightly.  Almost no one designs trains to race each other, but smoothness starting from stall is a definite plus there.  Slot cars are all about competition, and today's controllers take away much of the stump-pulling excess bottom end out of the equation.  So slanted lams never really caught on for our application, for good reasons.

Cheers!

[havlicek]

Mr. John,

 

Have you tried skewing the lams on a slot car motor...model trains do ot for smoothness and bottom-end torque....what comes to mid is one of those

5-pole large diameter arms with skewed lams...

 

REDD

 

Yes I have...many times.  These have been done often in the past as well and reduce the cog effect that strong magnets can have (depending on their shape to a degree) by sort of making the arm behave as if it's crown were wider.  Barney later told me that he had some VERY effective skewed-lam arms that were very fast and delivered their torque in a more controllable way.  Skewing the lams will increase the total length of the wire on each pole as Dave mentions, but that slight increase of resistance (for a given wind spec) is no big thing.  Here's an old picture of one I did some years ago:

 

I *think* that at least part of why you don't see more of these around is because it IS a mind-tweak to wind these, and takes a little getting used to.  It may also complicate things (I don't know) for machine-winding, but you'd have to ask the guys who know about such things.  I wouldn't be surprised at all to find that they are still used by some folks.

 

-john

[Gator Bob]

Gator Bob, if you read all the words instead of 'skimming' you might not have to look stupid asking questions that were already answered.   

 

Lam insulators as shown above

 

Theory - Now there are 3 pieces of 'iron' with 3 smaller width but overlapping 'magnetic fields' vs. one wider field.. 

 

Skewed and insulated it might 'appear' to act as a pseudo-nine pole rotor.      

[CaptREDD]

Mr. John,

 

Back to skewed lams....Looks like timing would be hard to figure...would you advance as per leading edge of lam...or the "middle" of the road???

 

[running around in a feeble brain are visions of a 5-pole skewed lam short stack 36D arm(GE Silver Hornet length) with NEO's in the strap can and wound with 24-guage wire running on a 3/32 reamer-bank motor-shaft and that running on class 7 ball-bearings...and a truly no-blo com]

 

REDD sees the men in white coats with big NETS

[havlicek]

The timing would still be figured from the top center of the stack and the relationship to the com tabs (segment centers).  It would be necessary to build a jig accounting for the skew and always skewing the stack the same exact amount in a production situation to get repeatable results.  For the occasional "one-off" such as what I do, it's not all that difficult to land "in the ballpark".  

 

-john

[Gator Bob]

Rufus, have a look at a Tradeship MK-70, skewed arm w/ adjustable brush timing.

[boxerdog]

Or a Lindsay. I think it might be a good idea (sometimes) to reduce cogging, but I am not sure what the end result would be???

[havlicek]

The batch of sample arm blanks I got from a Chinese train motor manufacturer were 5 pole skewed lam.  The individual lams are about the best 5-poles I've come across for hand-winding.  They're roughly 26D diameter on 2mm shafts, and I've taken them apart (kind of difficult to get the powder coating off them) and pressed them as "straight"/regular stacks for some slot car motors, but can't recall having used them as-is.  Anyway, skewed lam stacks are still widely used outside of slots, and probably in slots too.

 

-john

[Hermit #1]

John, do you think this commutator might be suitable for a slot car project?  It measures 2.3mm (.090) I.D., 5.6mm (.220) O.D., and 12mm (.472) long.  The inside might need a very slight ream to take a 3/32" drill blank shaft, the outside is just small enough to fit inside modern endbell hardware, and there's enough excess that it could be shortened a bunch if needed.

[CaptREDD]

This is the WRONG place for what I think needs posting...oh well...maybeso Mr. Cheater will see it and move it to a better location...

 

PA Watson is a champion racer..he has a tips section on the Texas Slot Boards...they are well worth reading and considering....mabeso this link has alreddy been posted..if so erase this post...

 

http://excoboard.com...13097/1619773/1

 

 

 

REDD

[havlicek]

John, do you think this commutator might be suitable for a slot car project?  It measures 2.3mm (.090) I.D., 5.6mm (.220) O.D., and 12mm (.472) long.  The inside might need a very slight ream to take a 3/32" drill blank shaft, the outside is just small enough to fit inside modern endbell hardware, and there's enough excess that it could be shortened a bunch if needed.

 

Hi Dave,

 

     Yes, those are suitable for a slot car motor.  I know that because I have some and have used them, but the one you linked to is (of course) for 5 pole motors.  He also has some for 3 pole, but I don't know what the shaft size is on those.

    ***Key for these and higher performance (ie: high revs) slot car motors is how the copper shell is "connected" to the phenolic core.  Best is if there is some mechanical "keying" between the two, rather than *just* the bond between them.  When the copper is formed with internal "dovetails" of similar, it makes it much more difficult for the copper to fly apart.  Slitting the copper to form the individual com segments naturally weakens the whole com assembly, so a mechanical "key" helps make up for that.  Of course, all the old coms weren't done this way and they generally held up OK...for what they were, but armatures today routinely spin at ungodly speeds and are also subjected to heat stresses far in excess of what say an old Tradeship com would experience.  The old Kirkwood and Mura coms held up surprisingly well with insanely hot winds, but those old "blowproof" coms DID blow (so much for advertising!).

 

     ***if you look at a com and try and imagine how the forces are acting on it while spinning, the top will be the weakest part, because there's not so much phenolic up there on many types of coms.  Also, the bottom of the com can be protected somewhat by tieing the com down there.  Having the com "capped" should be the way to go for ultra high-revving armatures, but I don't even know where to get proper caps (anodized aluminum).  Keying the copper shell to the phenolic is really important and the only way to know if this is part of any com's design is to slice the com apart to see a cross section.

 

     ***Aside from keying the com shell to the phenolic, extra phenolic at the top and bottom of a com (because the phenolic isn't slit-through with the shell) helps to beef it up.  The com in the eBay link has a good amount of the extra phenolic which is also of course an insulator which means the com can't short on either a metal spacer or the end bell bushing/bearing (no fiber washer needed).  Fiber washers do wear much faster than bronze or other metal washers, so it's better to not use them if you don't have to.  Definitely DO use a fiber washer if the com looks like it might short though.

 

That's all I got!

 

-john

[havlicek]

This is the WRONG place for what I think needs posting...oh well...maybeso Mr. Cheater will see it and move it to a better location...

 

PA Watson is a champion racer..he has a tips section on the Texas Slot Boards...they are well worth reading and considering....mabeso this link has alreddy been posted..if so erase this post...

 

http://excoboard.com...13097/1619773/1

 

 

 

REDD

 

 

Well...I went through a bunch of the tips and didn't see anything about motor building, and definitely nothing about the subject of this thread, so it seems pretty clear this should be somewhere else.

 

-john