Drill bits for Metal: black bits or silver? Also speed versus size

Carlow52

Was in a fastener shop yesterday where they had a metal box of drill bits: 1mm to 10m in 0.5mm increments, 10 pieces of each = 170 bits. cost 90 euro plus vat

I asked about the quality and was told that,the fact they were silver, as-opposed to black, meant they were very good quality.

Any thoughts?

Also, anyone got a link to a chart for drill speed versus diameter of bit for metal for a drill press.
Thanks

cnocbui

The ones which appear gold plated - titanium nitride coated - are possibly a better bet. Personally I would do some research and buy a reputable brand, rather than just take someones word for it.

SpitfireIV

Carlow52 wrote: »

I asked about the quality and was told that,the fact they were silver, as-opposed to black, meant they were very good quality.

Any thoughts?

A neighbour of mine gave me a loan of a few larger dia. drill bits recently (12-16mm) to drill metal, and like the bits you mention they were silver, very shiney! I thought it a little odd, but I think he said they were Makita bits, so good quality. Now, i dont know what make yours are, maybe they are made silver to copy makita?

mp22

hss drill bits 25.4mm bit aprox 200rpm with coolant half the bit size double the rpm
applies to mild steel