Hawera HSS-G precision drill bits ( Bosch - China )

[Kiriakos GR]

Those HSS-G precision drill bits they are special for a very specific reason.

The word precision is the keyword, they have just a bit of extra hardness but their edge is actually sharp like a knife.
When you do assembly or actually manufacture customized electrical power boxes, or control boxes loaded with small switches, or even working with aluminum panels about making again custom designs, there is no better drill bits than the HSS-G.

The correct use of the drill bits is almost a small chapter of theory.
Factors like high temperature, wrong RPM speed, poor lubrication when drilling hard metals, it can destroy those double-sharpened HSS-G drill bits.

The word precision actually translates that the hole it would be 100% centered and that it is immediately usable (clean cut) for mounting your part to it.
Therefore those HSS-G they do boost productivity and they do what they promise.

Havera & Bosch HSS-G drill bits are actually the same, my selection was mostly based in the local availability and also pricing.

About pricing for its one drill bit, just multiply the mm (dimension) by one EUR, the largest 10mm is priced between 7.60 to 9.50EUR.
I did manage to cut it in half and this is how I learned the price. 

Below is a set of pictures for your information.
The chart about RPM VS drill bit dimensions is something which I have print and is hanging over my wall as life time reference.

Regarding drill bit lubrication, a good friend of my machinist, gave me one solution which containing special oil and water, which is the actual stuff that they use in metal lathe.

Therefore if you follow all those notes and warnings, your HSS-G drill bits will do the rest for many years to come.
 

 

[giorgos]

Regarding lubrication I have heard too, that it depends according the surface you want to drill.
For example if you want to drill aluminium you can use alchool.
I found the chart about speed/diameter very useful, and I think that it would be a great invent , to make a drill which varies speed automaticaly, according the drill diameter placed in chock. 

[Kiriakos GR]

I will start with a soft grammar lesson .. the correct word which even me discovered recently is Chuck

About the auto speed adjust according to drill bit diameter, it would have a value if all drill bits was alike in their properties.

[giorgos]

I have a relative question too. If your chuck have max diameter 13 mm , and you have to make a drill with bigger diameter than 13mm, is there in market HSS-G drill bits with diameter >13mm (at drilling edge) ,but 13mm or less in the edge that inserts to chuck?

[Kiriakos GR]

For out of the ordinary occasions, I am using those three Ninjas 

I can not even guess the brand name of the small ones  ( 100% Japanese letters)
But I did find the webpage about the larger one.
http://www.marvelcorp.co.jp/global/hole_cutters.html 

[Phyllomedusa]

Oh well, the Hawera ones are fine. Sadly my last Bosch drills I bought were not very sharp and so I changed manufacturers.
I use some DeWalt extreme drills for Masonry (DT6956-QZ)  which I paid 11€ for a five pcs. Box (4,5,6,8,10mm). When I unpacked them I noticed that they are Made in Germany, but I don't know the original manufacturer. They work great and last quite a while now. So they are really Great for the price! Last but not least....quality isn't only affected by it's origin or brand name ;-)
The Bosch ones I had bought before (Silver Percussion) were not as balanced/round as the Dewalt ones and actually a bit more expensive. So drilled holes always very a bit fringed. The DeWalt ones are smooth and really circular.

For Metal I switched to Pfeil HSS-Co drills. You have to be very careful as they are very hard and therefore break much easier than normal HSS ones, but they are very sharp and long lasting.....and last but not least they are built for strong metals or Stainless Steel. Very nice ones, but a bit more expensive......well, but much cheaper that the big brand names in that quality range.

@giorgos: Be careful when you use very large drills in your machine. The motor has a limit ;-). So if the drill doesn't fit it is probably better to use the hole cutters like Kiriakos has shown (depends on the Material of course.....don't even try granite or so ;-)). But even there chances are quite good that you damage your machine when you use hardwood.
My brother tried to cut a 45mm hole into oak to install some lighting with his green Bosch drill....well, he ended up with two holes and two replaced drilling machines.....

[Kiriakos GR]

and two replaced drilling machines.....

  LOL   

[Phyllomedusa]

...yep.... and maybe also having something learned ;-), but I am not sure about that :-D.

[giorgos]

Phyllomedusa, thank you for your advice. Also welcome back to the forum after long time

[Phyllomedusa]

Thanks Giorgos! You're welcome...