Grinding Twist Drill to drill brass.

gus · Sep 2, 2014

Our Twist Drills are not designed to drill brass and copper.

Just how many of us will take a gamble not regrinding a 8 mm drill to drill a brass job piece which had a lot of work done and drilling the same hole to complete job.
There is a very good chance that the drill will get snatched in and pipe flange for the Nemett-Lynx Engine ruined. :wall:
Drill ground to spade profile and hole drilled with no snatching and job done. Carby mounted on inclined.

gus · Sep 2, 2014

I have many sad and grievous happenings when drilling brass on the drill press and lathe.
Please feel free and invited to post your happy and sad encounters.
Hopefully this thread will eliminate ruined brass job pieces.
Regrinding the drill took 10 seconds at most. Making a replacement piece can take hours or even days.

SmithDoor · Sep 3, 2014

Dill the drill bit and keep the relief angle very low
Also keep the lip angle to 160 deg. or more
Dave

gus said:
I have many sad and grievous happenings when drilling brass on the drill press and lathe.
Please feel free and invited to post your happy and sad encounters.
Hopefully this thread will eliminate ruined brass job pieces.
Regrinding the drill took 10 seconds at most. Making a replacement piece can take hours or even days.

Herbiev · Sep 3, 2014

I found that drilling into a brick to dull the bit makes drilling brass easy

Omnimill · Sep 3, 2014

I'm not very good at hand sharpening drill bits so I wish you could buy them specifically for brass...

ShopShoe · Sep 3, 2014

I have had good luck dulling edges with one light pass down my bench stone. Drill is handheld and each cutting edge is run over the stone once. These are HSS bright drills with 118-degree points. I have done this down to No. 49 size, so I don't know if I could do it with even smaller ones.

The other part of this procedure is that now I have drills for brass only, I don't try to resharpen small bits. I buy good-quality small sizes in multiples and only sharpen larger drills.

Hrcoleman66 · Sep 3, 2014

As brass is a copper alloy, it behaves a little like copper and will grab drills and turning tools as it pulls them in. Bronze is less likely to behave like this but it can do.
I do not tend to grind the negative rake on my drill bits as I hate to have to regrind again for steel ( maybe keep two sets of bits? One for brass/bronze and one for steels)
Turning tools should also have a negative rake for brass and other copper alloys. I myself just grind a profile on a high speed steel blank and leave the top of the blank flat. I never use carbide tools on brass.
Cheers,
Hugh

gus · Sep 3, 2014

ShopShoe said:
I have had good luck dulling edges with one light pass down my bench stone. Drill is handheld and each cutting edge is run over the stone once. These are HSS bright drills with 118-degree points. I have done this down to No. 49 size, so I don't know if I could do it with even smaller ones.

The other part of this procedure is that now I have drills for brass only, I don't try to resharpen small bits. I buy good-quality small sizes in multiples and only sharpen larger drills.

Hi ShopShoe
Good idea. Will buy a 1.5-------6.5mm set and grind them for brass. Will have this done this/next week. Regrinding 6.5------4mm should easy but I give up on 3----1.5 but one good thing is the grab is not to aggressive and can be countered by using the quill feed stops,lowering the drill bit 1/4 turn or even 1/2 turn.

Lotsa advice coming in.

abby · Sep 4, 2014

If you are not happy grinding your drills a diamond file will work equally well , just a couple of light strokes will put a negative rake on the cutting edge , I did a new 5.8 mm just today and used it to drill several pieces of brass bar for tapping 1/4" x 40 tpi , it works just as well with smaller sizes.

gus · Sep 4, 2014

abby said:
If you are not happy grinding your drills a diamond file will work equally well , just a couple of light strokes will put a negative rake on the cutting edge , I did a new 5.8 mm just today and used it to drill several pieces of brass bar for tapping 1/4" x 40 tpi , it works just as well with smaller sizes.

Hi Abby,

Good idea. Will use your idea to dress smaller drills 4 mm and below.

3mm drill will also snatch though not as strong.

As of 4 August, I have started to grind some drills for drilling brass. Box is marked.
Letter spacing error but added on the last '''s'' to read '' BRASS''.:hDe:

Herbiev · Sep 7, 2014

A tin of miniature bras Rof}Rof}

Larry S · Jan 26, 2016

I use the Fine Down Feed on my Rockwell vert. mill and always
set the depth stop so even if it does grab a bit it doesn't go past
the depth I need. The fine feed is a worm and wheel arrangement
so it doesn't jerk down.

Larry S
Ft. Wayne, IN

Blogwitch · Jan 26, 2016

All you need to do is get an Arkansas stone or diamond slip and stroke it gently downwards over the cutting face to take off the edge or do as I do and purchase a set of 'Bullet' drills, these have a small drill bit on the tip and flat cutting face like a milling cutter.
These can be used on almost any material, especialy thin sheet and they don't leave any burrs on the bottom side.

http://rover.ebay.com/rover/1/710-5...0001&campid=5338413729&icep_item=300950106027

John

110samec · Mar 17, 2016

Negative rake is also used to prevent snatching when drilling fibreglass. Usually i hold the back of the cutting edge against the grinder to flatten it off a little which works well

gus · Apr 28, 2016

Herbiev said:
A tin of miniature bras Rof}Rof}

May Gus be forgiven.Ha Ha. English was not really his mother tongue though was taught English by teachers from UK from age 7.

After a heartbreak and burnt out building the Howell V-2. After a good break and abstinence from machining for three months.I am back. The mini gear type lube oil pump really had me stumbled. Must admit Gus is no good for mini stuffs. Am making good progress and learning how to making gear pump using DIY mini gears. Will post on my Howell V-2 Thread shortly.

Trust the world is treating us well. Ha ha.

bazmak · Apr 29, 2016

God to see you back Gus hope you had a good break.Burnout is for work
not for hobby

goldstar31 · Apr 29, 2016

Glad to read that you are sort of OK

Best wishes

Norman

kvom · Apr 29, 2016

Maybe I live in an alternate universe (and don't have a drill press), but I've never had a problem drilling brass on either my mill or lathe. Both of these are heft machines, and that may make a difference.

kwoodhands · Jan 15, 2019

Omnimill said:
I'm not very good at hand sharpening drill bits so I wish you could buy them specifically for brass...

My grandfather had a set of drills only used for brass. They were straight flutes ,no spiral. They are still available. Ohio drill. or something like that still supplies them. Try a search for drills for brass.
mike

goldstar31 · Jan 15, 2019

Gus hasn't logged in for a year and half. Shame, he was a nice guy

N

Grinding Twist Drill to drill brass.

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