New pillar drill drilling triangular holes

[zymurgy]

As subject. Bench drill seems to be very vibey ? is there an adjustment on a Sip bench drill to make sure the drill chuck is running true. Any other reasons why i'd end up with a trianguar hole in thin sheet stock ? Drill bit is new (6mm) and is sharp and good quality.

Thanks

Paul.

[dave stanton]

Any

Drilling too fast ?

Dave

[Grouch]

Are you using Sheet Metal Drills?

[John Rumm]

Do you have something behind the steel to drill into? A block of MDF is good. Otherwise the sheet will just tend to catch as the drill breaks through and then spiral onto the bit. This gives the characteristic triangular hole you describe.

[Andy Hall]

It sounds like the workpiece is moving around, Paul.

Do you have it firmly clamped down and on a block of wood to back it up?

Is hte speed correct for the drill size and meterial?

If there's a lot of vibration when just running and the chuck looks out of true, check to see if it can be removed (i.e. has a Morse taper etc). It may be that there is a piece of machining crud lodged in there, so try cleaning thoroughly and reseating. Do this by locating the chuck, rest it on a piece of wood and steadily pull the handle to apply pressure.

[nightjar]

Although you say the drill is sharp, triangular holes are characteristic of a two-flute drill that is slightly blunt.

Colin Bignell

[john]

"nightjar .uk.com>"

A sharp drill bit can tend to 'grab' and give a triangular hole. When I was a toolmaker we had a dodge - too complex to describe but it gave the bit less of a positive rake (not clearance). Best to clamp the sheet between two sheets of MDF - this will stop the sheet from lifting. The pillar drill spindle is probably too light to resist being pulled and vinrating as the drill break through.

John

[zymurgy]

Thanks for all the replies. Food for thought. Will try to recentre the chuck, use a backing board and hold the work more firmly [1] !

Cheers

Paul.

[1] Was just wearing leather gauntlets, as it was a sheet of steel and not so easy to clamp down ..

[Andy Hall]

You could also try a dab of cutting fluid, Paul.

[John Schmitt]

Have you tried the cloth trick mentioned in the FAQ?

John Schmitt