DRILL & TAP A BUS

[JeffD]

If you are going to get this inspected the inspector may make you have a field testing angency certify the modified equipment. That is going to cost around $3,000.

 

[sameguy]

Silicon bronze is what we like on stuff like this. When I was "young, dumb, full of...it." I would do any job and never give it a thought. As I got older I stopped and will not do it hot at all; you making $ at the potential of me getting f'ed up, not no more! Turn it off.

 

[Alwayslearningelec]

FWIW ...

Ordinary general purpose drill bits won't drill copper well at all. That have what is known as a 118 degree point. Look at the bit from the end, and you can see the letter "S" formed by the contours.

What you need to use is a 135 degree "split point" bit. This bit has a flatter point, and when you look at it from the end you see a 'bow tie.'

Drill with a slower speed and greater pressure.

Thanks.

 

[Alwayslearningelec]

If you are going to get this inspected the inspector may make you have a field testing angency certify the modified equipment. That is going to cost around $3,000.

What determines if this is inspected?Inspector? Thanks.

 

[JeffD]

What determines if this is inspected?Inspector? Thanks.

If you pull a permit or not.

 

[Joethemechanic]

grading of bolts is not always "more is better". i've seen situations in off road racing
where a grade 12 engine mount bolt, thru bolted, will snap off in an hour of racing,
and the emergency repair piece of 1/2" running thread with two locnuts on it stayed tight
and didn't break for six months.....

I agree 100% with that one. Lots of times higher grade (higher tensile) bolts will fracture before a softer one will.

same with torque. more isn't always better.... you want the bolt slightly stretched, a
percentage of the amount you can stretch it without failing, like 40% or so. that's how
the torque tables were developed for fasteners.

I work on stuff like Cat that has a small initial torque spec to bottom things out, and then a fastener is moved a certain amount of degrees to it's final amount of preload.

Or like on some other big stuff like Waukesha where they use studs and nuts and you put a dial indicator on the top of the studs and mesure the stretch.

BTW, if you use the 135 degree bits, be sure to get a good center punch mark. 135 drill bits tend to walk when starting.

 

[sii]

BTW, if you use the 135 degree bits, be sure to get a good center punch mark. 135 drill bits tend to walk when starting.

Use a good quality tap too, you'd hate to have to remove a broken one while the customer is standing there looking at his watch.

 

[electricblue]

Did one for 480v at a treatment plant. Have to tell you I was nervous. I always think of that old board operation, where you can't touch the side. Worked just fine. Just don't touch the sides or your dead...

 

[Alwayslearningelec]

If you pull a permit or not.

What bout union jobs? Always get a permit and inspection.

 

[ActionDave]

Anyone happen to have pics or video of this(drill & tap):roll:

I'll check Youtube

I'll see if the bookkeeper will volunteer to make one.

Your bookkeeper wants to do work hot, or do you want your bookkeeper in the video because she is hot?

 

[Joethemechanic]

Your bookkeeper wants to do work hot, or do you want your bookkeeper in the video because she is hot?

That thought only plays out well if we assume the bookkeeper is a "she"

 

[sparkcontrol]

Greenlee makes a drill and tap kit for thoes who want to use the correct bit and tap. Its all in one,bit and tap in the same piece. its from 6/32 thru 1/4-20