Dull drill bits.... drilling tips?

[stee1e]

I've been drilling 8mm holes in 3mm mild steel. I have a set of new HSS drill bits and have been drilling pilot holes starting at 4mm then 6mm and finally 8mm. The 4 and 6mm have been going through no problem but the 8 started to have problems on the 9th hole. It starts to squeal and stops cutting.

I'm currently using a corded hand drill as I don't have a pillar drill.

I've read this thread about drill bits and understand that quality HSS bits are important as is learning how to sharpen the drill bits. I'm watching a bit sharpening video as I write this. I was wondering is there any other techniques that I should be aware of when I'm drilling steel.

Thanks

 

[eSCHEn]

Divvent gan too fast

 

[brightspark]

u only realy need a 4mm 1st then the 8mm they only squeel and rub when there blunt .are u using cutting compound and are the drills of good quality . u should be able to drill a lot of holes with them . are u running the 8mm fast or slow

 

[rtbcomp]

Use some decent cutting fluid such as Rocol.

 

[stee1e]

Yeah definitely blunt so will need to sharpen them. Not using any cutting compound, will this do the job Screwfix cutting compound

The drill bit are Erbauer from Screwfix as well.

What speed should I be drilling?

 

[brightspark]

Yeah definitely blunt so will need to sharpen them. Not using any cutting compound, will this do the job Screwfix cutting compound

The drill bit are Erbauer from Screwfix as well.

What speed should I be drilling?

about 1.000 rpm on steel with a 8mm drill i wouldnt class them as a good quality drill

 

[Badger1bear]

I bought a set of drills from these guys and the cutting compound and they KICK ASS, just have a look at the videos on their website

http://www.ttp-hard-drills.com/

 

[stee1e]

about 1.000 rpm on steel with a 8mm drill i wouldnt class them as a good quality drill

What drill bits would you recommend?

Thanks

 

[brightspark]

dormer presto guhring sherwood standard hss, nothing fancy

 

[mart]

I've been drilling 8mm holes in 3mm mild steel. I have a set of new HSS drill bits and have been drilling pilot holes starting at 4mm then 6mm and finally 8mm. The 4 and 6mm have been going through no problem but the 8 started to have problems on the 9th hole. It starts to squeal and stops cutting.

I'm currently using a corded hand drill as I don't have a pillar drill.

I've read this thread about drill bits and understand that quality HSS bits are important as is learning how to sharpen the drill bits. I'm watching a bit sharpening video as I write this. I was wondering is there any other techniques that I should be aware of when I'm drilling steel.

Thanks

I`ve found that using a pillar drill/press makes a massive difference to how easy it is to drill through steel. They don`t just help to line the job up good and square, they make the drilling action almost effortless. Highly recommended.

I got mine for a steel project about 4 years ago, and have used it for timber jobs too. If you drill a hole on a thick piece of timber the drill bit comes out in the right place-directly below where you started, not way off the centre.

 

[mart]

What drill bits would you recommend?

Thanks

The best bits I ever bought were some of them they call multi-construction drill bits, from T Station. Apparently they can be used for masonary or steel. You have to go nice and steady with them-no forcing, just let them do the work. I`ve only used them on steel and prefer them to Dormer. They sell them in sets of about 4 or 5 which works out a bit cheaper. Or, you could buy one just to try.

I never drill "dry", always use something to cool & lubricate is my advice, even if all you have to hand is oil, otherwise the bit will be shot in no time.

 

[fizzy]

I find going too slow on the feed the worst culprit for blunting bits.

 

[ukracer]

I bought a set of drills from these guys and the cutting compound and they KICK ASS, just have a look at the videos on their website

http://www.ttp-hard-drills.com/

My concern would be how to grind them once blunt??

 

[normspanners]

Slow rpm and steady pressure, do not let the drill skid on the surface, that is what blunts any drill in steel.
also crap steel nowadays with lots of incursions in the alloys

 

[normspanners]

I agree that you should not use the 6mm you are not allowing enough of the 8mm cutting edges to work correctly.

 

[stee1e]

Ok. So, cutting compound, slow RPM, steady pressure, sharp drill bits (learn to sharpen), smaller pilot hole and a set of decent (but not necessarily expensive) drill bits.

Thanks all

 

[langy]

If you use a Dormer A002 split point drill and fluid at the right speed you could go straight through in one go easily

 

[brightspark]

Ok. So, cutting compound, slow RPM, steady pressure, sharp drill bits (learn to sharpen), smaller pilot hole and a set of decent (but not necessarily expensive) drill bits.

Thanks all

smaller drills use higher speed on the pilot ..the 8mm @ 1.000 rpm . the pilot size only needs to be the size of the chissel edge on the final drill to stop it scraping rather than a clean cut

 

[PhillipM]

My concern would be how to grind them once blunt??

Just like any other drill, they're still HSS, just modified with cobalt for more high temperature hardness, to be honest, for this job any decent split point drill with a bit of lube should go through in one go.

 

[Rig Pig]

I've been drilling 8mm holes in 3mm mild steel. I have a set of new HSS drill bits and have been drilling pilot holes starting at 4mm then 6mm and finally 8mm. The 4 and 6mm have been going through no problem but the 8 started to have problems on the 9th hole. It starts to squeal and stops cutting.

I'm currently using a corded hand drill as I don't have a pillar drill.

I've read this thread about drill bits and understand that quality HSS bits are important as is learning how to sharpen the drill bits. I'm watching a bit sharpening video as I write this. I was wondering is there any other techniques that I should be aware of when I'm drilling steel.

Thanks

Take it steady and use a pilot drill the size of the chisel edge of the drill - the flat bit in the middle, over drilling the pilot will tend to make the drill snatch and flake the cutting edge.