74 replies to this topic

[havlicek]

Got it, Robert. For one, none of the spring cups I have here will fit the washers, and turning them down is a PITA.    Next time, I may just stick them on a 0-80 screw and nut and chuck them in my Proxxon. Getting the feel for what's actually going on here was sure a frustrating process.  

My aim here, as I said, is to use as much of an OTS Hawk as possible and build a budget friendly screamer. I know there's a load of potential to be tapped in these motors, but when you get much past arm-swapping, the whole "budget" part of the equation can get lost quick. At these intended prices, even the cost of the aluminum endbell is no small thing.  

 

So, refining the cost equation, the basic Hawk is like $17 and so is the aluminum end bell, so we're up to $34. A pair of the less-expensive bearings would be another $15, so we're up to around $50. Say another $5 for the 0-80 screws and washers per motor, and we're at $55.  That leaves $45 to hit... or be under the $100 mark when you get a hand wound/ground and balanced armature... as long as the racer does his own assembly. Of course, this could be even cheaper if it were coming from the factory R2R, but still, if I can get this done it should be a cool project. I even wound a #26 for this using the stock JK stack reshafted, and with a replacement comm. If a #26 can live in one of these, then a #25 would be the ultimate... but baby steps.
 

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I'm glad to hear it worked out.

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

 

Thanks, Mike. I wouldn't have gotten this far without your help. I may be "aiming high," but a budget "open-type" motor is what I'm aiming for. I believe most of the pieces of the puzzle are already there, but putting them together is the thing!

[JK Products]

Where is the emoji for eating popcorn with extreme interest? Hmmmm...

[Robert BG]

John,

I'd love to see a budget motor such as this used in a old school piano wire chassis like we used to use in I-15 back in the day.You could also use a milder wind in a brass/wire car too if someone wanted.It would make a really cool "Retro Style" wing car class that could be run alongside retro as we know it.Basically a cheap class of cars that flat out fly and are fun to actually drive and are affordable to race.

 

As far as "hand wound"arm costs go a few of the classes I run now (I-15 and HB Box 12) all allow the use of hand wound arms and they cost $55 over the counter at any track compared to 35-45$ for machine winds.Whats funny is I've got plenty of cnc wound arms that are just about on par with the hand winds.It's just the hand wound arms are more consitant and there's a lot less of them that are culled for being dogs.So it's usually cheaper to run the hand wound option  I figured I'd mention this since most people think of the 100$ opens/euro's and 80$+ group 27's when it comes to hand wound arm cost.

 

Mike,you're probably right that sanding the backs isnt needed but for the 10 seconds it takes while prepping hoods I just keep doing it.I also chamfer the holes like you mention and lastly I'll hit the edges with a file at some point too.Again probably not required but there's usually a little spot in the Koford hoods that needs to be filed down for the brushes and springs to ride freely.So a few extra strokes of the file never hurts

[havlicek]

JK Products, on 16 Apr 2017 - 11:09 PM, said:

Where is the emoji for eating popcorn with extreme interest? Hmmmm.....

 

Stay tuned then Tim, and grab the xtra jumbo sized popcorn while you're up by the concession stand.

 

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I'd love to see a budget motor such as this used in a old school piano wire chassis like we used to use in I-15 back in the day.You could also use a milder wind in a brass/wire car too if someone wanted.It would make a really cool "Retro Style" wing car class that could be run alongside retro as we know it.Basically a cheap class of cars that flat out fly and are fun to actually drive and are affordable to race.

 

 

Exactly Robert.  A Hawk in a simple/light piano wire perimeter or "tripod" chassis with a hot wind would fly.  Of course, for me personally, cars need to have actual front wheels, even if they simply flop up and down, but I digress.

 

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As far as "hand wound"arm costs go a few of the classes I run now (I-15 and HB Box 12) all allow the use of hand wound arms and they cost $55 over the counter at any track compared to 35-45$ for machine winds.Whats funny is I've got plenty of cnc wound arms that are just about on par with the hand winds.It's just the hand wound arms are more consitant and there's a lot less of them that are culled for being dogs.So it's usually cheaper to run the hand wound option   I figured I'd mention this since most people think of the 100$ opens/euro's and 80$+ group 27's when it comes to hand wound arm cost.

 

Yeah well, the irony here is that, for me anyway, the work is the same for a 65/30 as it is for a 21/25.  When I send them out for grind/balance, I don't say..."this is only a mild wind so don't sweat it and just "get it close".  Really though, what I'd like to see most is a fast wind from the factory in an almost stock Hawk that's pretty reliable...AND with replacement factory arms available, "plug and play".  The motors that are gone over to the last photon are a thing of beauty no doubt, but having this all come "stock" would be where the real cost savings could happen.  So, if any of this helps inspire that eventuality, it would be the ultimate payoff.  I could never be an armature manufacturer, nor would I want to be.  I'm happy doing what I do for the small number of people willing to play along.

 

MSwiss, on 16 Apr 2017 - 8:22 PM, said:

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

I routinely do what i can to flatten the hoods on these and even C and D can motors when I'm going over a motor and giving it "the treatment".  I can see how it *might* help on at least the minicans and will also spend some time "peening" the hoods flat(er) from both sides as best as I can.

[chasbeeman]

John,

 

I tinkered with the JK aluminum endbell and was able to press fit a 5mm unflanged bearing into the opening without much difficulty. There for not needing epoxy or super glue.

[LindsayB]

These are used a lot in the Grp F pro class that runs out of Tennessee. That class runs a Grp 12 arm in the Hawk style setup.

 

I have set up an endbell and pretty much followed the normal process I would use for a 27 or Grp 7 motor. I used the JK brush hoods because the screw holes were not compatible with Cahooza stuff.

 

First set, install the bearing in the endbell, glued and set using Koford yellow epoxy. Second step make sure brush hoods are flat and line up correctly using brush hood tool with a shaft hole (endbell fixed onto the setup with a dummy shaft). As Swiss said brush hoods directly on the alloy endbell.

 

If all good - go to the assembly stage. Get 4 anodized alloy 0-80 screws (Koford or Alpha sell them), 4 nylon screw insulators - a few people make them - Koford have them. Next step, yellow Koford glue on the underside of the brush hood, place brush hood on still using aligning tool, put nylon washers on screws, place epoxy on screws and then tighten down - remember alloy screws so don't overtighten or they will break.

 

When both sides are done take endbell off the can - pull out the aligning tool (you may need to back off one screw per side to tool to come out freely). Then take endbell and bake to set epoxy. When done I then use a diamond coated brush hood tool to clean out hoods (being carefull not to expose the endbell to the cutting side of the tool).

 

Hope this helps.

[havlicek]

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Hope this helps.

 
Well... better late than never!    A good portion of what you wrote would apply to any endbell, but the real issue here was with shorts, and the anodized alloy screws aren't neccessary. Regular steel (or stainless steel) 0-80 screws work fine. In any case.  

 

Thanks for chiming in though, and I'm sure this information will be a help for a lot of people.

[havlicek]

chasbeeman, on 19 Apr 2017 - 01:14 AM, said:

I tinkered with the JK aluminum endbell and was able to press fit a 5mm unflanged bearing into the opening without much difficulty. There for not needing epoxy or super glue.

 

Same here. The first one I tried was actually really difficult to get in. The second one, I fashioned a tool to press it in exerting pressure across the whole face on the bearing. In both cases, the bearing is a very tight fit... almost worrisome it's so tight. Definitely no need for anything else to hold it in place.

[chasbeeman]

I purchased mine new from JK website and it came with instructions to scrape away anodized finish with an X-Acto blade for easier fitment. I'm curious what the best method you found that created no shorts?

[chasbeeman]

My project was started by using a Pro Slot VR extreme armature in a Hawk 6 setup, it was a screamer until the plastic endbell melted (a result of the amp draw on that high-timed arm). Pro Slot doesn't spec the timing but since it's designed for drag racing, I expect 40 plus degrees.

 

I was trying to build the most powerful motor short of a cobalt setup. The class we were racing ended and have not been able to test the motor with aluminum endbell installed yet. I may need one of your custom wind arms with less timing to extend the life by less heat build up.
 

[havlicek]

chasbeeman, on 22 Apr 2017 - 12:28 PM, said:

I purchased mine new from JK website and it came with instructions to scrape away anodized finish with an exacto blade for easier fitment.

 
Oh... well, that sure would have been good to know beforehand (scraping the inside of the bearing pocket). The darned things are very tough to install, and it can't be good for the bearings to have to use a press to fit them.

 

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I'm curious what the best method you found that created no shorts?

 
All I did was to open up the bottom hole of the hoods a little to make sure the screw/washer would self-center without touching the hood.  The spring cup is something of a problem because those tiny Koford washers are really too wide for the inside of the cup and can easily crack getting them in there. I secured the hoods and screws with a tiny bit of my armature epoxy, figuring it would be better than Loctite... and I kept the screws only slightly "snug." I just did another aluminum endbell and it has no shorts either... maybe I just got lucky twice. I do wish there were other choices for those little washers though.
 

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I may need one of your custom wind arms with less timing to extend the life by less heat build up. 

 
No problem. I almost never go above around 20 degrees advance unless asked. I recently did a couple of hot #30 winds (*I know... it sounds weird to say "hot" and "#30" together) with only 50 turns and 30 degrees advance, and the guy I made them for got back to me to say the arms run great in a ceramic Hawk setup on a twisty flat track. Then again, even a "hot" #30 is still a pretty reasonable arm.

[chasbeeman]

I found it and took a pic; hope you can read it.

[LindsayB]

If a bearing is a tight fit, rather than bash it in, put the endbell in boiling water for a few minutes and then install the bearing

[Phil Hackett]

The bore for the bearing can be anodized to size. When making the endbell the bore needs to be oversized by a set amount and then the anodizer is sent the parts and a gage for the desired fit. A interference fit of more than .001" on a 5mm bearing (I just committed the holy crime of mixing metric and Ennglish units, sorry) is pretty severe. The hot water is a good idea, so is placing the endbell in a toaster oven at 250°F.
 
Scrapping off hard coat anodizing: that type of anodizing is sapphire hard.

[havlicek]

LindsayB, on 22 Apr 2017 - 11:08 PM, said:

If a bearing is a tight fit, rather than bash it in, put the endbell in boiling water for a few minutes and then install the bearing

 

No "bashing" here, but the bore is most definitely too tight on these.  I hope this thread is a helpful document for others just trying all this for the first time, because I'd hate to think I've been going through all this for nothing!  These end bells are very nice, and I don't want to be seen as bad-mouthing them, but so far (between avoiding shorts and now installing the bearing) there is a definite ...er..."learning curve" involved.  I happen to have a 5mm end mill, but I never thought I might need it for this.  This all reminds me of early failed attempts at building armatures.  Oy veh!

[MSwiss]

You should be able to reduce the diameter of the 5MM BB by the same way I would rough up the OD of the BB before I solder it in on the can side.

Put it on the comm end of an old armature, with a spacer between the comm and BB, and lightly hit it with a Dremel 409 disc, at about a 30 degree angle.

[havlicek]

MSwiss, on 23 Apr 2017 - 6:48 PM, said:

You should be able to reduce the diameter of the 5MM BB by the same way I would rough up the OD of the BB before I solder it in on the can side.

Put it on the comm end of an old armature, with a spacer between the comm and BB, and lightly hit it with a Dremel 409 disc, at about a 30 degree angle.

 

Which is pretty much exactly what I did...the second time Mike.    If I do any more of these, I'll try using an end mill in my hand and see how that works.  These are awfully tight without doing at least something.

[Dave Crevie]

I wouldn't use an endmill to open the bearing bore. Being that it is helixed, it could grab and damage the bore. A reamer

of the proper size can be flat-ground on the end so that it will cut to the full depth. 

 

Jerry sent me samples of these many years ago, and I don't remember that the bearing was all that tight. I don't remember

what brand of bearing I used, but since I would have bought them from Mike Swiss, I would guess they were Koford. Anyway, 

I built two motors, one went to Jerry as he wanted some info on how they fit, the other I still have. I built mine with a Pro-Slot

12 arm for their 4000 series can. It ran way hot with the neo magnets, so I never used it. 

[Robert BG]

I dont know about the JK's but on others where the bearing is a tight fit I use my iron to heat the endbell tower and a can of Duster to freeze the bearing on the end of a old arm and they'd go together perfectly.

[havlicek]

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I wouldn't use an endmill to open the bearing bore. Being that it is helixed, it could grab and damage the bore.

 

Higthly doubtful when using the end mill by hand.  I have pretty strong hands, but not that strong.  

[Dave Crevie]

Believe me John, I learned about this a long time ago when trying to open holes a few tenths with an endmill. It

is almost impossible to hold the cutter exactly in line with the centerline of the bore. The sharp edges will dig into

the aluminum and cock the cutter.

[havlicek]

I hear you Dave...but believe me, I can deal with this  Really, it would have been nice to know ahead of time what I was in for here, but now that I do know, it's all good!  The funny thing here is that, I ask for information about a specific thing and (*aside from Mike Swiss), I get information AFTER  I've already experienced the pain.  

[Robert BG]

John,you should be happy Swiss replied because I can still hear the crickets chirping in the thread where I asked some questions

I would've tried to help sooner had I saw it but honestly I dont check here that often.

It really seems that folks are getting away from building motors.Even in the wing car classes most guys just call a builder and have them built and while I dont have a problem with that,for me a big part of the fun is building and trying new things.

[MSwiss]

I saw your question, but have never had one in stock/seen one in person, so I couldn't help you.

John obviously has, so maybe he can help you with the dimensions you were looking for.

http://slotblog.net/...-endbell-specs/

[Robert BG]

Mike,

Thanks and John helped me out earlier in this thread. I know if you could've helped that you would have and if my post came across otherwise towards you I apologize.I just find it funny that if you or John cant answer a question,then chances are it may go unanswered It  seems to prove that more and more people are going with built motors these days instead of building their own.