3573 replies to this topic

[HarV Wallbanger III]

Wow! John 'yer gett'in ta be a regular factory!

[Alchemist]

Looks like candy John! Sweet!!

Ernie

[havlicek]

Hey Ernie...thanks buddy. Some really interesting and challenging things going on in the motor department lately, thanks to a connection I made right here on Slotblog. Boy...just the motor thing is so deep, it sometimes seems like I'll never "get there". Then again, just trying is a helluva lot of fun and even being "close to getting there" is pretty cool

-john

[One_Track_Mind]

Nice triple play of motors John!

I'm liking the signature H on the stack, makes us all remember who done it.
Like we could ever forget getting one of your righteous motors!

[havlicek]

Thanks Brian I have a Champion FT16D I'm working on now trying to find ways to get them to run below melt down temperature but still perform...and this one is "special". What makes it more difficult is that I want them to look right for the period, so swapping endbell hardware or even the whole endbell (which would be the first place to change things) is out of the question. It will be a LOT of work...I hope it's worth it

-john

[HarV Wallbanger III]

Although I did not ask for them out of his care pak I sent him, (I have some to send to him later that I hoped to get custom done) he sent me all 3 of these! Thank you very much John! Beautiful work!

[havlicek]

You're MOST welcome Barney and I look forward to doing those custom jobs when you figure out how you want me to go with them. BTW, I was going through the stuff you sent and there are some deadly C-can magnets in there I haven't seen before. They inspired me to do some unholy experimenting What in the heck are those things?

-john

[HarV Wallbanger III]

??????? me no tell!

[havlicek]

Well...even as the mystery continues Barney, I have done something fun with a set of them so...thanks!

-john

[Alchemist]

Hi Barney!

That's some packaged "candy" you've got there! Looks real sweet with the different colors!

Hi John,

Perhaps you may not realize the impact you've made by sharing your "rewinds" with us, along with the technical info you provide along with the great pictures of your work. So for that, I thank you very much John!!! I wish to also thank all the other members that have been helpful with their responses to my inquiries.

Now, if I may ask another technical question please?!

If the air gap between the armature and the magnets are too close for your requirements, how does one "open up the air gap; tools, method/technique please? Also, what about the reverse situation where the air gap is too big?

Thank you!

Ernie

[havlicek]

Hi Ernie,

If the air gap between the armature and the magnets are too close for your requirements, how does one "open up the air gap; tools, method/technique please?

There's a couple of ways I can think of. For one, not all magnets are the same thickness so it is sometimes possible to get a magnet that's either a little thicker or a little thinner. The way to do it with a given set of magnets is to use a hone. These are short/round slugs of a given dimension with diamond abrasive on their circumference (because ceramic magnet material is difficult to sand) and a shaft like an armatiure running through the center. You start off with a magnet/can setup that leaves a "hole" for the arm that is smaller than what you want it to be. By working up from a hone that will abrade the hole when powered (drill, dremel etc.) to the next size etc., you can get a hole that is not only the right size for the armature ("air gap")...but which is perfectly centered/symetrical around the arm's center. This whole deal makes a real mess because the dust is (of course) magnetic and sticks to everything. When the magnets have been glued into the can, getting all that dust out of there is a pain in the neck. There's putty you can shove in there (although even plumber's putty can work) and you can also wad-up tape with the sticky side out and shove that in there until it comes out clean.

Also, what about the reverse situation where the air gap is too big?

That's the easier of the two...sort of. When the hole is too big, you can make it smaller by installing shims behind the magnets made of thin steel and pre-curved to fit the radius of the inside of the can and back of the magnets. If you have to shim the magnets a lot , you may have to use different magnet clips as the ones intended for the setup will start to deform rather than to work properly. Thin steel shim stock is relatively cheap and is a mild grade so that curving it isn't too bad. You can also cut it without it deforming as it would if you used a shear, by using a straight edge and scoring it a bunch of times with an X-Acto knife. Once it's been scored enough, you can let it hang off a solid surface and while keeping the straight edge over the score...start to gently bend it until it "gives". After you've cut strips, you can cross-cut it easily with a Dremel to length. I keep a bunch of .003" or .004" (I forget which) and it's a good thickness for most jobs...either singly or by putting two shims per side in the motor. To make installing the shims easier, it's good to radius the corners of the shims so they can be slid into the can behind the magnets with the front edge of the magnets being held just outside the end of the can.

For really thick shims, sometimes it's good to go back to the old "can-in-a-can" deal. For instance, you can make a "can-shim" for a D-motor (or an old Mabuchi-style FT16D) by carefully thinning out the sides and top of a modern c-can. It takes a while, but usually the top and bottom (flat sides) of a C can need less thinning-out than the radiused or curved sides. I do all the sides in passes as evenly as I can first with a thin diamond wheel and then finish them off with progressively finer sandpaper by hand until it seems as though the C-can will slide into the D (or FT16D) can. Then it's just a matter of cutting off the bushing end of the C can and trimming the other end as necessary. I then start the C can into the FT16D by hand and finish installing it by inverting the whole mess on a piece of glass and gently pushing the C can in. FT16D cans DO vary a thousandth or so ...especially between "types", but this is usually do-able with some effort. It's also not a method that was unknown back in the dark ages as "can-in-a-can" shims were sold by Dynamic, so for the "pure of heart" that can't stand the idea of "cheating"...this might be acceptable Once this is done, the benefit is obvious as most modern C-can magnets will just pop right into a Mabuchi setup and produce a tight air gap as well as a really strong field. You can also use modern D motor magnets in Mabuchis as they are strong magnets and pretty much a direct fit...but they leave a really large airgap and need to be shimmed anyway.

The final thing about fitting magnets is the "top-to-bottom" size (height) of the magnets and not all magnets for a given can are the same height. If the height is a sloppy fit, the magnet clips will just slide between the magnets and the can top and bottom and not secure the magnets. Even if you're going to glue the magnets in, the clips can be a handy way to temporarily hold them until the glue cures. Sometimes you can just make thicker clips out of piano wire...sometimes you have to make thin shims for the top and bottom of the magnets. I've also seen it said here (I forget who) that shimming the magnets top and bottom works better with non-magnetic shims (brass) than with magnetic ones (steel). I just use steel and it seems OK to me, but maybe brass is slightly better...that would be above my paygrade!

-john

[Bill from NH]

I'll add, prior to the availability of the diamond coated hones, hand sanding was probably the most common means for fitting magnets. Not only could they be different thicknesses, often the magnet faces had to be trued to make them flat. All this took a great deal of time, if done right. Today's magnets are made more accurately & easier to work with.

One way to increase a can's airgap is to use a can-straightening mandrell. Straightening a can will almost always result in stretching a can slightly larger.

[havlicek]

Good one Bill...I've never done any can-straightening, so the idea of doing that to gain a few thousandths (besides truing up/squaring the can) never occurred to me. Thanks!

-john

[Kim Lander]

John...you and I need to talk some day about mags....you have hit on some thing that me and another oldtimer that I have raced with since....well ..a long time..anyways, I`ll call you soon and tell you what I`m talking about....Kim

[havlicek]

OK Kim...I'm all ears

-john

[havlicek]

A JK Hawk for Ernie:




then:




Then:




I backed off the stock timing, but did a stronger wind. It runs exceptionally smooth and doesn't get too warm at all, but has lots of torque and brakes. This little motor should be a strong runner and last well.

-john

[Victor Poulin]

Hey John,

That better not be faster than mine or I'll have to ask for a refund Oh,, wait ah minute, you didn't charge me ! Never mind

Looks real nice John. If it runs as good as the one you wound for me, Ernie is going to be very happy with it. Maybe you should start doing some replacement arms for the Hawks. As far as I know, no one is making any yet. As you know, the Hawk is one of my favorite motors. At least one with a good arm in it


Vic

[havlicek]

Hey Vic...this one wasn't done for top-end, but more for reliability and torque. :Like you, I really like these little motors. They're small enough to stick just about anywhere, have good strong magnets and a real endbell and are capable of some nice performance\.

Maybe you should start doing some replacement arms for the Hawks. As far as I know, no one is making any yet.

Nah...but maybe a bunch of people should start a Hawk rewind class...stock motor, any non-factory wound arm. Like THAT would ever happen

-john

[Victor Poulin]

Like THAT would ever happen

-john

That pretty much said it all John !!

[Bill from NH]

John, JK sells Hawk "take-out" arms for $5.95. Maybe not as far-fetched as first thought.

[Alchemist]

Wow - awesome John!!

If you'll pardon my "lack of knowledge" please - but the directional arrow is pointing parallel to the armature shaft - I'm confused as to which direction the motor is suppose to turn?!

Did you find any concerns with the way the arm shaft fit into the end bushings, e.g., misalignment etc., as was mentioned when you first looked at the HAWK motor??


Hi Vic!

What type of chassis have you employed with the HAWK please? How does it run?

Thank you - thank you - thank you John!!!

Ernie

[Victor Poulin]

Wow - awesome John!!

If you'll pardon my "lack of knowledge" please - but the directional arrow is pointing parallel to the armature shaft - I'm confused as to which direction the motor is suppose to turn?!


Hi Vic!

What type of chassis have you employed with the HAWK please? How does it run?

Thank you - thank you - thank you John!!!

Ernie

Hi Ernie,
I,ll be honest, I haven't yet. I'm just hanging on to the one John wound . I have done a lot of playing around with these Hawks though , and you can really go wild with them if you want to. The one John wound sounds like a strong running X-12 on the power supply. I did one up with a ProSlot open arm, roller bearings both ends, redid the endbell using Mura hardware, camen heavy springs, BF2 brushes, shunt wires, and the thing was a bear !!! I'm looking foward to doing alot more with these things.

[havlicek]

Hi Ernie,

Glad you like it

If you'll pardon my "lack of knowledge" please - but the directional arrow is pointing parallel to the armature shaft - I'm confused as to which direction the motor is suppose to turn?!

I couldn't fit one of my stickers on the usual place on the can. The arm only has a mild advance (around 12 degrees), but it will run better in the "normal" CCW direction (as viewed from the endbell)...or clockwise as viewed from the drive or can end. It's a sweet little motor indeed! Like Victor, I think they're about the best bet for hotrodding...better even that the SCX RX42 motors...better endbell and an even more compact package. Can you say 1/32 sidewinder???

-john

[havlicek]

John, JK sells Hawk "take-out" arms for $5.95. Maybe not as far-fetched as first thought.

But where's the fun in that Bill???

-john

[Alchemist]

Thanks for clearing up my confusion John!

Ernie