3573 replies to this topic

[idare2bdul]

Stack weakening is never a problem till it lets go. I've had some arms with, "Journey to the center of the Earth," balancing holes that held up fine and others that seemed to know I didn't really want to replace the magnet it was about to break.

[Prof. Fate]

Hi

If you don't blow up an arm now and again, you ain't really trying!

Fate

[chaparrAL]

Crash, Burn or WIN!!

[havlicek]

Hi Bill,

Oh I was referring to the center drill's point angle and the length of the pilot. By the time you get to the wider section of the drill, the pilot is already so deep that it could cause a problem weakening the stack if you're off side-to-side. I don't really have any problems breaking the bits, more that after a couple of months they get dull...so I toss them

Stack weakening is never a problem till it lets go. I've had some arms with, "Journey to the center of the Earth," balancing holes that held up fine and others that seemed to know I didn't really want to replace the magnet it was about to break.

...welcome to my world Mike

If you don't blow up an arm now and again, you ain't really trying!

...hmmm, then I must treally be trying!

-john

[Krash]

Thanks for all of the comments, well see how it runs when it's all put together.
If it grenades then that is fine, as it will be part of the learning curve.

Pablo – The balancer I am using is home made, try this link...if I did it correctly
http://slotblog.net/...ic=8714&st=1217
If not it's post 1218 of this thread.

Doug – Yes it's a ProSlot arm rewound, trying to use up some old arms as I practice. Once I think I know what I am doing I will try and move onto newer ones.


Thanks Everyone


K

[Bill from NH]

Oh I was referring to the center drill's point angle and the length of the pilot. By the time you get to the wider section of the drill, the pilot is already so deep that it could cause a problem weakening the stack if you're off side-to-side. I don't really have any problems breaking the bits, more that after a couple of months they get dull...so I toss them

If one was using center drills to drill balance holes, you'd only use the pilot portion of the bit, otherwise you'd end up with a 1/8" dia. hole. If one pilot hole didn't remove enough material, you have the choice of drilling a second & third pilot hole or increasing the size of the first with a 1/16" or 5/64" bit. The tapered portion of a center drill works great when beveling holes for flathead screws in sheet metal & for cutting the surface area for a lathe's points to rest.

I have an Eclipse brand drill sharpener. It's a British made wheeled plastic guide holding the bit that gets rolled across some 320 grit or finer paper. It works fairly well when the bit just needs honing but if you got to remove any serious metal, you need a motorized unit.

[Champion 507]

Kelly,

I too have 2 or 3 ProSlot arms I want to rewind but just don't have time to right now. I'm definately going to put hotter winds on them. I may even replace the comms and really make 'em rip.

While my plate is overflowing with other priorities right now, it's allowing me to think of very devious motors to build once I can get back to it.

Meanwhile, I'm glad to see others getting involved in rewinding. It ain't that hard and the rewards can be quite nice. Look at it this way: Thomas Edison found hundreds of ways not to make a sucessful light bulb. We don't have it that tough.

[havlicek]

If one was using center drills to drill balance holes, you'd only use the pilot portion of the bit, otherwise you'd end up with a 1/8" dia. hole.

Gotcha Bill, and that's what I would do as well. I was referring to what Kelley did and it seems as though he used the full bit...both to drill the pilot and then the larger holes. It looks like he actually went pretty far in with the wider section of the center drill as well because the shoulder cuts seem fairly deep. In order to do that with a center drill (even if you used a drill press and were at precisely 90 degrees to the face of the stack), I can't see how the stack wouldn't be signifcantly weakened. Making progressively wider "chamfers" by only just barely cutting with larger bits seems about the only way to get a wide and shallow cut unless you use an endmill. Even though it's the absolutely completely wrong without a doubt application I have meant to try brad point bits for this by drilling a pilot and then using VERY light pressure with the brad point bit. I'm sure this won't work...will probably make the drill grab and jump and ruin an arm, but I will try it sometime on a junk arm just to prove it to myself This would produce an essentially flat-bottomed hole much like an endmill if it worked...but Im sure it won't

Kelley,

You and Robert have the right idea when it comes to this stuff. Dig in and just do it because it really doesn't matter at first what happens. You'll be gaining experience and a kind of mad-scientist enjoyment out of it all!

-john

[Bill from NH]

John, not to belabor the point further, the bradpoint bits I've seen & own are made for wood. They wouldn't be properly hardened or made from a steel for drilling in metals. How about trying one of the small Dremel milling bits for the flat-hole look? Next time you go to the dentist, ask if he's gotten an "dull" grinding burrs. You never know what you could end up with.

[havlicek]

John, not to belabor the point further, the bradpoint bits I've seen & own are make for wood. They wouldn't be properly hardened or made from a steel for drilling in metals. How about trying one of the small Dremel milling bits for the flat-hole look? Next time you go to the dentist, ask if he's gotten an "dull" grinding burrs. You never know what you could end up with.

10-4 Bill...that's why I said it probably wouldn't work. Worse, it could be dangerous because if that thing grabs a lam and yanks the arm, it could drill your fingers if the person were unwise and chose to hold the arm while doing this

-john

[havlicek]

I just finished-off a batch for Jeff Easterly. Three of them (the tagged ones) are a wind he asked for and the fourth shorter one is a replacement arm for the Walnut motor (I drilled too deep and it tossed a lam). The three tagged arms started out as Mura Challenger arms, and epoxied arms are always a PITA to recycle ...BUT...they're great quality and of course hadn't been balanced. The Walnut arm is a new Mura .007" blank and com I shortened to an overall length of just over .900". All four arms also got new shafts and all four also got treated with the black goo for anti-short insulation. The stuff seems to wrok very well and no problems of any kind were encountered. I guess I'll be using the stuff from now on.


-john

[Robert V.]

Very nice John they look powerful, what gauge wire did you use on the one with out the tag it looks a little thicker.

[havlicek]

Hi Robert,

Thanks. The three tagged armes are #27 winds and the short stack arm is a #26. The three tagged arms are about .3 ohm and the shorty is .2 ohm and #26 wire makes a hot arm that is still sort of reasonable in the right setup.

-john

[Bill from NH]

John, the two middle arms look like they were balanced by using a center drill. I did a Google search the other day on "furnace cement" & found colors other than black (in case someone doesn't like black). IIRC, they were tan & gray.

[havlicek]

Hi Bill,

Yeah they do don't they Of course the pilot hole would have been deeper and probably would have ruined the arms Now you got me on the lookout for light-colored furnace cement. The stuff really does seem to work really well. I was able to get a nice heavy build on these arms without gooping-up the inside of the web. I also really yanked pretty hard on the wire to see how the stuff would hold up and had no problems either with it chipping off or with shorts. Sometimes I get lucky!

-john

[Slotgeezer]

YAAAA-HOOOOO !!!!

Yeah, buddy! ... That's the stuff!... WOW! ... Impressive....

John & I had discussed the 'Steube-20' arms I ran, as a kid... Bill would wind 35T of 27 wire on the then-available Mura .007 blanks, & I thought that this wind, in an older two-hole Mura set-up w/ longer-length magnets, would be a real kick to drive!... The Challenger I blanks are shorter than the original blanks Bill used, but that shouldn't be a problem... The ' H20+ ' tag lets the builder know that it's John's work, & a tad 'warmer' than a standard Gp20 wind.... ... I plan on building something 'period-correct' from that era ( '74 or '75 ), & it'll be fun driving it on the BP King track..

As always, many, many thanks, John... Bob "Stork" Crane was kind enough to hand me a few older two-hole Mura C-can set-ups, w/ long-length Mura & Champion Blue Dot magnets in 'em, so I should be set to set 'em up, & let 'em spin!...

& yes, I will post photos... I love sharing my attempts at re-living my youth thru running John's armatures... As I build-up the motor, & assemble the chassis, I'm taken back to when I was 17 or 18 again... It's a BLAST !!!

Take care, everyone!


Jeff Easterly

[havlicek]

You're always welcome Jeff. I'm temporarily without a power supply so I couldn't give them the old test-spin, but they all meter fine. Have fun!

-john

[Bill from NH]

You didn't burn it out using the automatic winder again, did you John?

[havlicek]

THANKS A LOT BILL ...believe it or not, I'll probably now be getting some PMs asking me how much I paid for my CNC winder. Sometimes when we're sure people will get the joke, it just goes right past them

-john

[BoomerDog]

John, I just received your package and I've just got one thing to say.........
WOW!
I mean........HOLY S**T!
Well, I guess I made my point....absolutely fantastic and over and above! Thanks so very much!

[havlicek]

Hi Steve,

I'm glad you liked it and it was my pleasure

-john

[Alchemist]

Hey Congrats Steve on your "Havlicek Powerhouse Motor!"

I can understand your excitement upon receiving a motor from Sir John H. I have to confess that each and everyday I need to take a look at the motors I've had the privilege of having "woundup" from Sir John and each and every time is like taking a peek at something I could not imagine I would own! Now - that's exciting!

Thanks again Sir John H. for your time, effort and generosity.

Ernie

[havlicek]

I made up another "walnut" motor arm today. The stack was assembled using extra Mura .007" lams I had here to a length of around .335" and the com was a reclaimed Mura. Overall length comes in right at .904", which is right "there" for a new Mura C can cut down to about as far as you can without going to shorter magnets or weakening the can. The com and tail spacers were made from the ball ends of electric guitar strings I use .012" strings for making springs for Mabuchi rewinds and had kept some of the balls so this seemed like a good use for them. I took a turn off this one (the others were 27T/#26) so it's a 26T/#26 that comes in right around .2 ohm...that oughtta wake the neighbors. These are cool little motors that I think make good use of the length of the stock magnets while getting rid of some extra flab from the can.



Now I have to cut down the can to the right length, and I'm not sure where I wrote down that dimension So maybe it's "cut & fit" time.

-john

[Alchemist]

Gollllllly John!

I really need to have one now! What an awesome piece - as usual. So, you play guitar too?!!

Ernie

[havlicek]

Hi Ernie,

I've had a pretty good amount of interest regarding the "Walnut" motor. There have been all kinds of versions and variations of this sort of thing...mine is based on the short arms like the X-12 that go in C cans. Since the arm should be shorter than the magnets because the field generated by the moving coil doesn't just go out perpendicular to the arm but off the ends as well, it seems that these short arms are somewhere about "right" for the short magnets in a modern C can. Then when you stick one in a C can...the can seems kind of long for what's inside (leaving aside the role the can plays in producing the field along with the magnets). So hacking the length of the C can to just about the minimum without cutting the magnets seems like a good idea. The result is a short and light motor that still has a lot of punch with simple off-the-shelf parts that are inexpensive too (including regular ceramic magnets like Mura Red Dots). It would seem ideal to put this motor in a light perimeter frame with a body that has some air control to take advantage of both the rpms as well as the light weight and Jeff Easterly's car for his Walnut looks like a great example. We used to run G20 motors in cars like that and they were a boatload of fun. This is like an extreme example of that...with a lighter and faster motor.

I also have done something similar based on a cut down SCX can which is much slimmer and maybe even shorter than the C can-based Walnut thanks to the very slim magnets in there. Those are very cool too.

-john

(I play keys...organ, piano and synth, I even sing...er...I mean croak a little too, my sons play guitar and bass )