74 replies to this topic

[havlicek]

Yes, you are reducing the heat transfer between the brushes and hoods, to the aluminum endbell.

 
OK, that at least makes sense.  At least at this stage, it seems to prove that the issue here is the point of attachment...the screws.
 

You can not count on anodizing in the threaded holes to act as an insulator.

 
Yep, I saw where you had posted that before Mike, so even though I was concerned, I blasted ahead anyway...and failed!
 

At Koford, the drilling and tapping was done after hard coating.

 
More proof that the tapped screw holes losing their anodizing (these seemed to have been anodized after drilling and tapping, as the red color was in the screw holes) shouldn't be a problem.
 

Maybe it's time to post some good pictures. 

 

That would be nice, as well as a step-by-step guide to assembling this hardware. I mean... it's not like I haven't tried to do the same thing here... hundreds of times.  

[MSwiss]

I meant you posting pics of the one you are having problems with.

[havlicek]

I meant you posting pics of the one you are having problems with.

 

Well, that's no problem Mike...I can sure do that .  I meant what I said though!  In any case, I don't know how a picture of an assembled end bell will help, but I'll get busy anyway.  

[MSwiss]

Maybe we can spot an obvious issue.

Will you be able to glue the hardware down,with tape in between it, and the endbell?

[MSwiss]

 

 but testing from buss bar to buss bar reads as a short.

Are you testing with a multimeter, or a power supply?

 

Again, you really need to post pictures.

[havlicek]

Here's a photo Mike,  Both the spring cup and bottom screws have the washers so the spring cup screw heads aren't in contact with the cups (which are also anodized), and they also aren't in contact with the hoods on the lower screws.



 

 

 

Will you be able to glue the hardware down,with tape in between it, and the endbell? 

 

 

I already removed it since it's not necessary.  I can then glue the hardware down, but I don't remember reading here that should be done!?

[havlicek]

 

 

Are you testing with a multimeter, or a power supply?

 

 

neither, a simple buzzer built into my arm cradle, I'm sure you know what that is without a picture...a simple continuity tester is really all it amounts to, so when I'm metering the arms, I also get an instant short announcement.  I can test with a multimeter, but I don't see the point when a short is a short.

[wbugenis]

. Koford sells a yellow epoxy to secure these screws.
 
 

[havlicek]

Hi Bill,

I recall you saying that these screws were installed with a thread-locker, but not that using that was part of making sure there was no continuity from side to side. So... say Loctite is not OK, and you must use an epoxy?

[wbugenis]

I have never actually used the Koford Yellow either to secure the screws or to glue down the hardware but that's what it's for..
 
I use threadlocker and that's it!! Almost never had a short. A quick touch of high voltage always cured any shorts for me.
 
I almost hesitate to post that I 'hack"  the assembly like this, but it is what it is.
 
As I posted earlier, Swiss is the guy to listen to here.

[MSwiss]

If you have a robust power supply, turn it to max, and hook the leads up the hoods, and see if it pegs the amp meter.

 

One issue is, you don't need the bottom plates with an aluminum endbell.

 

They are not designed for aluminum endbells, and the bottom holes aren't much bigger than the diameter of the 0-80 screw.

 

Before you remove those bottom plates, remove the bottom screws and see if that stops the issue.

[havlicek]

I have never actually used the Koford Yellow either to secure the screws or to glue down the hardware but that's what it's for..

 

I use threadlocker and that's it!!  Almost never had a short.   A quick touch of high voltage always cured any shorts for me.

 

I almost hesitate to post that I 'hack"  the assembly like this, but it is what it is.

 

As I posted earlier, Swiss is the guy to listen to here.

 

Hi Bill...don't hesitate sharing info at all.  At this point, I'm getting information in painful and tiny dribs and drabs...except for being told that shorts are basically no problem!   I don't think I'm any kind of rocket scientist, but neither am I a complete dummy.  I'm fairly careful doing things...especially things I want to learn.  There is obviously something basic I'm missing here that everyone seems to think is "ordinary".  I mean, you screw the hardware to the end bell with the washers in the cups and under the bottom screws with regular steel 0-80 machine screws.  I may not be a rocket scientist, but this isn;t exactly rocket science.

[Eddie Fleming]

A quick touch of high voltage always cured any shorts for me.

What is considered high voltage in this case?

[havlicek]

If you have a robust power supply, turn it to max, and hook the leads up the hoods, and see if it pegs the amp meter.
 
One issue is, you don't need the bottom plates with an aluminum endbell.
 
They are not designed for aluminum endbells, and the bottom holes aren't much bigger than the diameter of the 0-80 screw.
 
Before you remove those bottom plates, remove the bottom screws and see if that stops the issue.

 
Hi Mike,

 

OK, so that is some new info (thanks!). Unfortunately I had already disassembled the end bell to remove the tape. So I will reassemble it without the bottom plates and see what happens. I will also give it all a jolt with as much juice as my PS will deliver (supposedly 20A at I think 15V) if I still get a short. I have to run out to see a client, but will try again when I get back.

 

I do appreciate all of the information here. I'm just a little frustrated and ticked right now is all.

[MSwiss]

It's occurred to me that your issues are probably based on using hardware, designed for a plastic endbell, on an aluminum endbell.

Note the pic below, on the size of the bottom hole on a Koford hood.

If there is enough meat on the JK hood, I suggest opening it up, to that size.

Also, I'm not sure of the ID of the cups.

To be safe, turn the diameter of the top metal screws down a touch.

With an aluminum endbell you are relying on epoxy, as much as the screws, to hold the hardware in place.

Sort of, the screws hold it down, but the epoxy keeps everything from shifting.

[havlicek]

Hi Mike,

 

Thanks again, I'll open up the bottom holes a bit, as they aren't all that much larger than the screws. On the cups, the ID is visibly/comfortably larger than the screw head OD, so that seems fine.
 

Sort of, the screws hold it down, but the epoxy keeps everything from shifting

 

Got it, I didn't crank the screws anyway, but I don't want to go ahead and epoxy the stuff in place until or unless I'm at least fairly confident I've done the installation properly.  

 

I hope all this information is helping others as well, because I can't believe I'm the only person who's ever had this kind of frustration with all this.

[MSwiss]

One last thing.

As I mentioned in another thread on this subject, you should be checking hood to endbell, using the exposed aluminum in the side holes.

Use the power supply method, and check as you install each screw.

This should tell you immediately if you make a mistake.

[havlicek]

OK Mike...

 

Success. I got the endbell reassembled and no shorts. I opened up the bottom holes on the hoods so they are about the same size as the holes up top. I guess that this allows the screws and washers to self-center and prevent the sides of the screw threads from contacting the hoods' holes. I assembled just those two screws/washers first and got no shorts.

 

After that, the washers are too big for the spring cups inside diameter, which would crack the washers when you forced the screws and washers into the cups. After looking around for cups that were larger inside (I don't have any), I turned down the screw heads a little as you suggested and then the washers just a little (that was tougher than turning down the screw heads). I still had to slightly force the screws and washers into the cups, but apparently everything was OK.  

 

Now that I have this part seemingly worked out, I'll put the endbell aside to order some unflanged 5mm bearings. When I get those, I'll do the real assembly with epoxy... and hopefully not have any problems. If I do have problems at that point, you'll be able to hear me cursing from Illinois. In any event, then I can always still try zapping the endbell as a last resort.

PS... I can't believe that whoever is using these endbells for the Hawk is going through all this. They must be using different hardware.

[JK Products]

Our hoods will work and apologize for not having a proper set of hardware for installing them. I will work with John and Mike (if they're willing to help me) to get a hardware kit put together. 

[havlicek]

Hi Tim,
 
Why apologize? Honestly, a lot of the "looking down your nose" at plastic endbells that you sometimes see is really kind of silly. The plastic is actually an excellent material for the task in most cases. Aluminum endbells are really probably only a good idea for really hot winds, and even at that, not for drags at all. In days gone by, everything up to the occasional #23 wire arm was run in motors with plastic endbells that were functionally really no better than what comes on the Hawk today. The Hawk motor is very cool stock, this stuff is only the "next step" and outside... way outside of anything it was designed for.

[Alan Dodson]

John,

 

You should try the Cahoza #266 hardware. It is plated aluminum, is interchangeable with the Hawk hardware, and is formed much more precisely.

[havlicek]

Hi Alan, and thanks for the tip. I will give it a try.  

Right now, I see a lot of potential in the Hawk and am looking at doing and spending as little as I can within the original setup's limits. I am convinced the little motor can go a lot further than a 65t/30, and be fast and reliable. I am not convinced that the aluminum endbell is absolutely necessary... up to a point. I have done #27 winds for these that are awfully fast and seem like they should live well. I think that a #26 may be the break point where things can change... especially for anything other than a drag motor.

[MSwiss]

I was at my nephew's wedding last night, and am just getting back to this.

I'm glad to hear it worked out.

I'm sure you build some awesome motors using this combo.

[Robert BG]

John,

I'm glad to see you got it worked out. I would've replied sooner but been busy with the holiday.

The first one can be a little frustrating. It was for me when I came back to slots and I'd done hundreds before but once you get the hang of it it goes pretty easy.

The two biggest problems I find myself doing are overtightening the screws and screw heads hitting the spring posts and I too would've recommended turning down the screw heads a touch.

Now when you go to do the final installation, just buzz each screw out as you go with a meter and chances are if you get a short you can just loosen it half a turn. If that doesn't work you may have to replace the insulator as they can get mangled. I know it sounds counterintuitive but, like Mike said, the epoxy and screws work together to hold everything in place.
 
Another tip is to smooth the backs of the hoods on some fine paper and make sure there's no burrs or anything to dig in around the edges of the hoods.
 
The first one is always a bugger and I myself must've torn the first one I did recently down five-seven times before I was happy. But once you get in the swing of it it'll go easier.

[MSwiss]

While probably not necessary, but I used to use a larger diameter drill bit, and chamfer the holes on the side facing the endbell.