Drilling T-Track?

[Tarheel]

I just picked up some of the 1/2" Rockler T-Track with assorted 5/16" bolts and jig knobs for $10.00 a kit. Great price!!!!

While making up some jigs, I found that I needed to drill extra mounting holes in the t-track - no problem! My issue comes when I try to countersink the holes drilled.

Is there a source for a countersink for aluminum? I tried Woodcraft that gave/sold me a countersink for a #6 screw that was the right size, but it dulled after about 6 holes! The countsink would have to be about 5/16" in order to effectively sink the screw heads to track level. I also tried a 3/8" countsink that cut ok, but with the run-out of my drillpress, left nicks in the track - ugly!!!

Bottom line. What do you guys to drill and countersink holes in T-track for yer jigs????

Any help at all would be appreciated!

Thanks,

Wayne

[Tom Miller]

Your first approach was good, but your countersink bit was not. Get a better bit -- if it's HSS, it should hold up to aluminum just fine.

I drill, and countersink that t-track all the time. I know what you mean about dinging the sides, too!

Regards,
Tom

[Tarheel]

Your first approach was good, but your countersink bit was not. Get a better bit -- if it's HSS, it should hold up to aluminum just fine.

I drill, and countersink that t-track all the time. I know what you mean about dinging the sides, too!

Regards,
Tom

So I am curious, Tom. Where do you get the HSS countersink bits from? The Woodcraft bits are really no good to me. (I think that the bit needs to be about 5/16" for a #6 machine screw.)

Thanks,

Wayne

[lcm1947]

I had the same Rockler t-track and the same thing happened to me although I used a #8. I had already noted to use a #6 the next time. My countersink bit held up though. Got mine at either Lowe's or HD. Can't remember which but I know it was one of them. You might try getting one from them. I got a 4 pack that had #6 thur #12 bits in it. But can't remember the manufacturer. Sorry.

[LCHIEN]

Now guys there are two kinds of bits they call countersink bits.

One is really what I'd call screw pilot drills, they drill a stepped hole with a small hole at the bottom for the threads, a bigger dia hole in the middle for the unthreaded shank and an chamfered countersink at the top.
Like this:

I would not use this set on aluminum.


The other is a true countersink bit which just drills the chamfered hole, generally concentrically on top of a hole already drilled.
Like these:

(Both illustrations courtesy of Lee Valley)

Something like the second Lee Valley set will drill nicely in aluminum.
or the Vermont American ones below:
http://www.vermontamerican.com/Produ...191018&I=70897

BTW, 82° is the standard chamfer for flat head screws. sometimes there are 90° chamfer countersinks, but I would not use those.

[lrr]

I just picked up some of the 1/2" Rockler T-Track with assorted 5/16" bolts and jig knobs for $10.00 a kit. Great price!!!!
[...]
My issue comes when I try to countersink the holes drilled.

Is there a source for a countersink for aluminum?
[...]

Thanks,

Wayne

Wayne,

Check these out. Single cutting edge, so no chatter. It is a lot of money to spend for an occasional need, but maybe they sell just one (I didn't thoroughly check).

But, you might check other sources for metal working tools and find something similar... I'd say just Google "metalworking countersink" or other phrase.



http://www.grizzly.com/products/g5728

[LCHIEN]

Wayne,

Check these out. Single cutting edge, so no chatter. It is a lot of money to spend for an occasional need, but maybe they sell just one (I didn't thoroughly check).

But, you might check other sources for metal working tools and find something similar... I'd say just Google "metalworking countersink" or other phrase.



http://www.grizzly.com/products/g5728

Those are 90 degree countersinks, not 82 degrees.

[Tom Slick]

The countersinks you guys are talking about are called "O-flute" countersinks. I prefer single flute countersinks. especially in aluminum I like to countersink first then drill the hole. it sounds backwards but you will get more accurate hole/countersink alignment that way. single flute c-sinks will let you do it that way.
mcmaster carr, jlindustrial, mscdirect, enco are all places to look for machinist supplies.

[Pappy]

I have a Mibro set from Lowe's that I have used in aluminum.

[LarryG]

Here's the perfect bit for this job.

I bought this three-piece set from Lee Valley specifically for drilling and countersinking T-track, in one operation. They work beautifully. The shanks are small enough to reach down into the track without buggering up the flanges at the top.

[Dan Tipton]

Of course, you could always carefully use a large drill bit of the same size to countersink the holes in the aluminum -- no special tools required....

[jarhead]

Of course, you could always carefully use a large drill bit of the same size to countersink the holes in the aluminum -- no special tools required....

Dan,
That is exactly what I did last week - worked great.

[LCHIEN]

Of course, you could always carefully use a large drill bit of the same size to countersink the holes in the aluminum -- no special tools required....

I've done that, too, in a pinch, but the angle is even worse than using the 90° countersink bit instead of a 82° bit. Twist bits have included angles of 118°. The flat head countersink is supposed to be 82°.

May seem like a small detail but all the force of the screw will be concentrated on a small ring at the bottom rather than the entire underside of the head.
depending upon the exact geometry the bottom of the hole will be distorted, perhaps allowing the rail to rise up some and the top will have a gap showing.

[Tarheel]

I bought this three-piece set from Lee Valley specifically for drilling and countersinking T-track, in one operation. They work beautifully. The shanks are small enough to reach down into the track without buggering up the flanges at the top.

That set looks like just the ticket, Larry! I just ordered a set from Lee Valley and it appears that they will definately work ok. The only concern I would have is them holding a good cutting edge for awhile.

Thanks so much to everyone with all their suggestions. (I really didn't think finding an 82 degree countersink would be this much trouble! )

Thanks again!

Wayne

[lcm1947]

Yes, thanks LarryG I'll be ordering a set myself. Excellent!