# Grinding Twist Drill to drill brass.



## gus

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.


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## gus

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.


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## SmithDoor

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.


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## Herbiev

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


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## Omnimill

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


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## ShopShoe

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.


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## Hrcoleman66

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


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## gus

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.


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## abby

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.


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## gus

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:


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## Herbiev

A tin of miniature bras Rof}Rof}


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## Larry S

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


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## Blogwitch

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


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## 110samec

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


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## gus

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.


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## bazmak

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


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## goldstar31

Glad to read that you are  sort of OK

Best wishes

Norman


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## kvom

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.


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## kwoodhands

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


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## goldstar31

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

N


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## john_reese

Years ago I had to enlarge the holes in a couple hundred brass parts on the lathe.  I bought half-round drills.  They worked perfectly.  No tendency to pull into the work.


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## Bronzewing

Search Amazon and such for slow twist drill. You seem to scrape brass more than drill it. I have managed to get a hold of some slow twist and they are great for brass. Just don't have a sharp edge like you normally have


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## Ken I

You need zero to slightly negative rake for drilling brass - particularly when enlarging a hole.
You can simply break the edge of your standard drill - you only need to break 0.1-0.2mm of the edge to the required rake 0° to -5° and it works fine - also you then don't have to grind back very much drill when resharpening it for normal use.


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## Clockworld

This guy shows a simple approach to giving your drill bit zero rake for brass: 

Matt


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## petertha

Bronzewing said:


> Search Amazon and such for slow twist drill.


I always thought slow twist had more to do with the flute helix angle & vacating chips optimized in different materials. Are you saying these things go hand in hand in a commercial drill? My own experience is that unless the rake is altered at the cutting edge, it almost doesn't matter what kind of flute occurs behind it because the grabbing has already started to occur.


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## metalmudler

Sharpen the cutting faucets to 115- 140 degrees.. less angle, less grab..


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## kquiggle

ClickSpring has a good video on this: 

I picked up a used (empty) drill index at a tool auction a while back. When I need to drill brass, I modify the required drill bit and then save it in the index for future use. Do this and eventually you will build up a collection of "brass" drill bits that you usually use.


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## Wizard69

The way to avoid resharpening is to build up a set of "Brass Drills".   Generally i like a slightly wider break, maybe as much as a half mm.   "Brass" Drills are also useful in other grabby materials, in fact I first learned of this mod when working in Lexan and other plastics.   A set of well maintained "Brass" Drills can be very useful if a person works a lot in these sorts of materials.



Ken I said:


> You need zero to slightly negative rake for drilling brass - particularly when enlarging a hole.
> You can simply break the edge of your standard drill - you only need to break 0.1-0.2mm of the edge to the required rake 0° to -5° and it works fine - also you then don't have to grind back very much drill when resharpening it for normal use.


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## kwoodhands

Omnimill said:


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



You can buy straight flute bits. These are made for brass and copper but are expensive. My grandfather had a set that I am sure he got from work. They look like chucking reamers. I did a search and found that Grainger has sets from 1/16" / 1/2" for only $718.00. 
There is info on you tube on dulling the flutes so the drill does not grab on brass.
If you need to drill large holes in copper than a step type bit does this very well. I needed to drill 1-3/8" in copper . I bought the bit at Harbor Freight for about $20.00. They may be called " Unibit".  You get 2 step bits ,narrow one probably goes  up to 7/8" or so and the larger bit goes to 1-3/8".
I have a new set of drills  that I have not yet modified for brass. The flutes are stoned dull . They work good for brass and still drill steel too.
mike


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