15 replies to this topic

[philk]

Been tool / mold making for 40 years but dont think I will ever enjoy drilling out 0-80 screws.

[havlicek]

I *might* try a #2-56, just to torture myself, and almost certainly fail.  0-80 would go straight into the trash because, well...as Clint said "a man's gotta know his limitations"! 

[Bill from NH]

John, if I compare the drill dia. to the 2mm bearing bore in the photo, it looks more the size for 2-56 rather than 0-80. Any motors i built had 2-56 screws used for hardware mounting & 0-80 for mounting the cans to the endbells.

[MSwiss]

I don't think any aluminum endbells ever used 2-56 screws.

I would go with what Phil says in his photo,that they are 0-80.

[Bill from NH]

it's nothing to me what size the screws are. In the posted photo, the drill bit appears to be larger than 1/16", which is the clearance bit for 0-80 screws.

[MSwiss]

Even though it looks like it would easily fit in the .078" BB bore, it's not worth arguing about.

[Phil Hackett]

Find left-handed drills (3/64 for #0-80) for drilling out screws. Also shorten up the drill. It's too long and will walk around. The best thing to use for drilling out short #0-80 screws is a left-handed #1 or #0 center drill. Remember to run them at high speed and the screw will be coming up out of the part.

[Rob Voska]

Sweet little precision vice ya got there!

[philk]

it's nothing to me what size the screws are. In the posted photo, the drill bit appears to be larger than 1/16", which is the clearance bit for 0-80 screws.

Drill is Tap drill size for 0-80, looks big in the pic though, hadnt noticed before I tried to take the screw out but it appeared to also be JB welded in the threads as was the brush hood. No wonder the aluminum screw twisted off, that screw wasnt going anywhere.

[MSwiss]

If you would of known ahead of time, you could of slattered your iron tip with solder, and heated the hood and screw, until the JB Weld smoked, and then you might of got everything out clean.

[havlicek]

I don't think any aluminum endbells ever used 2-56 screws.

I would go with what Phil says in his photo,that they are 0-80.

 

 

While not nearly as familiar with aluminum end bells as Mike, I assumed they must be 0-80 screws also because of the end bell type.  I also just assume people are not making things up when they post on the WWW, even though some are.  

[jimht]

Since it's a cobalt strap endbell, 2-56 is extremely unlikely...however, at one time RJR did make a C can aluminum endbell that used 2-56 screws.

 

I still have one around somewhere that I used as a jig for soldering brush hoods and buss bars together.

[Bill from NH]

Skip Lengel's SMF endbells out of Schenectady, NY were also aluminum endbells that used 2-56 screws. Skip used to anodize those for each can manufacturer a different color.

[MSwiss]

Yes, that was a bad idea, and racers complained of problems, with them.

For reliability against shorts, endbells need to to be hard-coated, not just anodized metallic red, blue, or green.

[Bill from NH]

People ran them in CASRA for a few years, prior to ISRA. i still have a couple to play with,

[Dave Crevie]

Mike is correct. Anodizing is not a good insulator. The brush hardware needs to be insulated from the endbell

to guarantee against shorts. I used .002 thick Teflon sheet under the hoods and backing plates, and Teflon 

tubing under the spring cup screws. A slight bevel to the end of the tubing at the cup end made sure the cups

stayed centered and didn't touch the screws. Same procedure for the short screws as well. (Teflon has a high

enough melt point to not distort)