I don't build panel in mass qty. so please be easy. I am looking a about a hundred J-Box with 6 (8-32) holes in each one. Just wondering how the pros do it. Do you use a cordlessdrill, tapgun, tapping head in a drillpress? The fixturing would not be a problem if I used a drill press 6*8" backplates.

Greenlee DTAP8-32 combination drill/tap. Use it in a cordless drill. Make sure you use a bit of light oil when tapping and don't put any side loads on the tap.

These things are great, just keep the RPM's down on the drill. You can order a set of the bits or singles. If doing the number of pannels you are doing I would get several extra of the size your using. You can get them at your local electrical supply store.

As for a Jig I lay out my plates then center punch where I need to drill this keeps the bit from wondering. Also make sure you clamp down your plate before you start drilling.

One more Vote for the Greenlee Drill/Taps. In my experience power tapping with a Drill I have found that you are most likely to break it when you are running it back out of the piece that you are tapping.

If you have a tapping head to use that would be the way to do it.



Jason

I use the drill / taps as well. I've never used the Greenlee with the 1/4" hex. My thoughts on these are... if the bit hangs in the steel it will most certainly break.

I use a standard drill / tap with a round shaft. This way if your bit hangs it will slip in the drill.

We also use a drill bit and then tap using a cordless drill.

Be careful about using a round shank tap in the drill chuck, the taps are harder than the drill bits and when they slip it will start to wear out the chuck jaws.

I have a set of Blue Point tap sockets (Craftsman also has a set) they have a square broached in the socket to drive the tap and an O-Ring to hold it in the socket, If you would use a socket adapter and a drill/driver with a clutch it would further reduce tap breakage.

Also use a good Cutting oil for the material that you are using (something is better than nothing though) and the cutting tools will last much longer and break less.

Jason

One of the beautiful things about the Greenlee drill taps is that they have a hex drive on them, nice for chucking in a drill or in a magnetic bit holder.





When tapping any hole you should reverse the tap every couple of revolutions. This breaks the chip that curls up in the tap flutes. Use a small cordless drill for this, the larger drills have too much power for a job that requires some finess. I actually put them in my Milwaukee cordless screwdriver instead of a drill, it has enough torque to tap up through #12. Be very careful to not put any side load on the tap, keep it straight and hold the drill steady. Side loading is usually what casues them to break. When deep tapping, reverse frequently and every few reverses run the tap all the way out to clear chips.

When going into anything other than sheet metal I use a regular tap for just this reason. If you are just tapping a back plane the greenlee's will work fine. If your taping a hole into thick walled steel tubing you probably need to switch to the convetional method.

Take a look at a combo bit. Once you get past the drill bit area your tapping a hole. If your material is thicker that the drill bit area you going to start tapping your hole BEFORE you finish drilling it. The combo bit was not designed for that.

I use the Greenlee Drill/Tap combo as well, if using a cordless drill with variable torque you can reduce the torque to just enough to get the job done, and reduce the number of broken bits.

Like the OP, I don't do much panel work at the minute. For holes I use a bi-metal hole saw that have a 7mm "guide bit" in the arbor. When I have my holes marked, I centre punch them, then drill a 5mm pilot hole, then a 7mm for the guide bit.

I use a Makita 14.4V Drill/driver, which has a torque limiter adjustable to 16nm. I drill at slow speed, triggering the drill with my right hand and spraying Cutting & Tapping fluid with my left. I find if you apply too much pressure at the end of the cutting, then the last bit doesn't drill from the panel, it snaps out, leaving a large burr lip around the far side of the hole. If this happens I use a deburring bit.

It takes me an average 1 minute to drill through 1.5mm thick stainless panel. (Does not include measuring, marking, centre punching, pilot hole drilling). I place a plastic bag (tape it) to the bottom of the panel to catch the swarf and cutting spray dripping down, and place some cloth at the back of the panel if it is already built to save having to clean way in at the back. When I'm finished drilling all holes, I pull the cloth forward and wipe all the swarf and fluid lying on the top down into the plastic bag.

Here are some stainless panels I was working on today (I didn't build the panels, just connecting the field devices):




Note in the 2nd pic I hadn't deburred the bottom of the holes when I took the pic.

HTH!

Regards - PG

I use two flute 'gun' taps in the cordless drill with a pilot hole just oversize from standard without trouble, the taps only break when they start to wear.