What Size Hole Do I Drill For A 1/2 Inch Bolt

Kjostad

Posted 3/2/2018 04:nineteen (#6614365)
Subject: Drill bit to hole size question....

Central, IN

So I am a footling stumped and more and so happy for some expert data in this area. I have bought winters drill bits for a long fourth dimension and take gotten along great with them. If I grabbed a 1/2 bit it would drill the pigsty and I could put in a i/2 bolt. Aforementioned with 1/4,3/8 etc etc. Best I tin can detect winters isn't really selling bits whatever more then I institute another company at the subcontract evidence that I idea was going to give me the same quality after talking to them. So I put together an order for what I needed to refill my stock which was a pretty skillful order becasue it has been awhile. I get to drill a half inch pigsty and can't go a bolt to become in. On top of that the hole doesn't look to be round but more than ob longed. I grab another new bit and same thing. And so I telephone call the compay and here is what I become told. Am told a ane/2 bit won't drill a hole for a 1/2 bolt. Instead I need to use a reamer later I drill the pigsty in society to make information technology work for a bolt????????? Are ya kidding me or is this for real. This is the starting time fourth dimension in my life of having this happen or hearing this. Please tell me if this guy is correct or not. And the ob long hole is my drill no matter what it has to be my drill. If I am wrong please tell me but I feel similar I just waisted a clamper of change. roydubs

Posted 3/2/2018 04:55 (#6614370 - in answer to #6614365)
Subject: RE: Drill bit to pigsty size question....

Never heard or that I would ship them back. dmax2001

Posted 3/2/2018 05:07 (#6614371 - in reply to #6614365)
Discipline: RE: Drill bit to pigsty size question....

Lawton MI

Unfortunately it sounds like you lot got some junk Chinese bits. I would transport them back. What they're maxim is a agglomeration of manure. John Smith

Posted three/ii/2018 05:xi (#6614372 - in reply to #6614365)
Discipline: RE: Drill scrap to hole size question....

S Key Illinois

Do you have a good fashion to measure the diameter of the bit?
Calipers?
Maybe take information technology to a machine store for measurement.

dkesler

Posted 3/2/2018 05:17 (#6614375 - in reply to #6614372)
Bailiwick: RE: Drill bit to pigsty size question....

Information technology takes .004 of an inch clearance per inch of diameter to go a bolt through a pigsty. Indianajones

Posted 3/2/2018 05:19 (#6614379 - in reply to #6614365)
Subject field: RE: Drill scrap to hole size question....

Machine shops generally use a .530 inch bit for a 1/2 inch bolt.
That being said, I can get a one/2 bolt in a hole I drill with a one/2 bit.
INDY Rod Maker

Posted three/two/2018 05:33 (#6614389 - in reply to #6614379)
Subject: RE: Drill bit to pigsty size question....

Westport, IN

I concur. I've always used 1/32 oversized bit when using bolts. I wouldn't even try to get a 1/iv bolt in a i/4 drill hole.

Also a two flute bit, peculiarly on sparse metal will make a oblong hole. It tin can be minimized with good clamping.

Was your old bits some kind of custom bits? Maybe have some pictures.

Clarkburn

Posted three/two/2018 05:33 (#6614390 - in reply to #6614379)
Subject: RE: Drill flake to hole size question....

Cornwall ontario

A perfect ane/2 inch hole shouldn't have plenty clearance for a 1/2 inch bolt to fit properly The scrap making an oblong hole would indicate information technology is not sharpened properly having one side of the cutting lips longer than the other Farmer at center OG.

Posted three/two/2018 05:36 (#6614393 - in respond to #6614365)
Subject: RE: Drill fleck to hole size question....

Wisconsin

I've seen it myself where certain drillbit's cutting oblong holes but seem to actually cutting pretty decent other than not a truthful hole. In my ruff drilling just ream it to fit no big deal to me. If I was a more than professional and required a good bit I'd purchase some and pay the price. Actually calling the company and getting that response would go my support and mayhap get their production returned in front of a farmshow crowd in a not so polite fashion. Byron ECIN

Posted 3/two/2018 06:48 (#6614497 - in reply to #6614393)
Subject: RE: Drill flake to hole size question....

Ive been using Winters Drill Bits for years. When drilling 3/eight drill fleck and then install a iii/8 bolt . I wish they were still in business.
Byron EcIn .
silagehauler

Posted iii/2/2018 07:32 (#6614627 - in reply to #6614365)
Subject: RE: Drill bit to hole size question....

I doubtable the previous bits were ever so slightly oversized to accomplish what yous say. Using the same size bit for a bolt is usually an interference fit for me.

Now if they just don't cut well, probably just not proficient bits.

Offroadnt

Posted iii/2/2018 07:39 (#6614650 - in respond to #6614365)
Subject: RE: Drill bit to hole size question....

Southern Alberta Canada

LOL, I'm so happy to successfully drill holes it never occurs to me they might be slightly undersized, I usually just blame it on burres or a worn bit, ream the hole with the fleck and carry on. I well-nigh ever become a 64th or 32nd over these days as well unless information technology's a critical fit project. If you recall nearly it most all holes in factory made stuff are very loose, anything that requires precision is aligned with dowels.

One thing that actually bugs me though is flatwashers, many are oversized about to the next size upward, what's with that?

Edited by Offroadnt 3/2/2018 07:40

hydro70guy

Posted 3/2/2018 07:44 (#6614662 - in reply to #6614365)
Subject: RE: Drill flake to hole size question....

Swaledale, IA

I would have asked them how tin my 1/2" drill bit fit in the hole and the aforementioned diameter bolt cannot? Magic Stone Road

Posted 3/two/2018 07:47 (#6614669 - in respond to #6614365)
Subject area: RE: Drill bit to hole size question....

westward/c Illinois

A regular twist drill will always make a hole that is shaped like a clover leaf. If y'all want a perfectly round 1/two" pigsty you lot will have to employ a reamer.

Edited by Rock Road 3/2/2018 08:07

School Of Hard Knock

Posted 3/2/2018 09:25 (#6614911 - in respond to #6614365)
Subject: RE: Drill scrap to hole size question....

merely a tish NE of cardinal ND

Nope....... a true half inch hole wont fit a true half inch pin or bolt.They are both the exact same size and at that place is interference, so a hole has to be tecnically a few thousanths larger for a non interference fit.. Mensurate you one-time bits and also your new ones with a micrometer, its the only way yous will ever know what is really going on...If your old bits fit one-half inch bolts and pins the center indicate may have been off eye and wobbled out a larger pigsty or they are larger diameter than they say they are.
The reemers are more for perscision sizeing a drilled pigsty and can be constitute in partial sizes to meet the needs of percision. Personaly, I dont own a reamer(just should)

Edited by School Of Hard Knock three/2/2018 09:29

ECIAfarmer

Posted 3/two/2018 09:41 (#6614956 - in reply to #6614365)
Subject: RE: Drill bit to hole size question....

East Central Ia, S. Waterloo

My fathers old Craftsman drill scrap set holder has three sizes listed below the chip. I for the fleck size below that the size to insert the respective bolt and a third for the tap size. Their not all the same, pretty handy. jimgen

Posted iii/2/2018 09:48 (#6614971 - in reply to #6614650)
Subject: RE: Drill bit to pigsty size question....

central mich

Off road

The departure in washers is The states vs SAE form.

If you buy U.s. class many times these washers will fit the next size upwards. Near farm stores and concatenation stores only sell US clase.

SAE class are smaller in OD than U.s. merely fit the bolt size.
Likewise in SAE you tin purchase different thickness washers.

We do not apply United states of america washers for anything unless
building wood crates or skids.

Edited by jimgen 3/ii/2018 15:xxx

PatCMO

Posted three/two/2018 xi:22 (#6615152 - in respond to #6614971)
Subject: RE: Drill flake to hole size question....

Pilot Grove, Missouri

Agree on the washers. I unremarkably use washers that are sold as one size smaller than the commodities I am installing. Patrick Illinois Steve

Posted 3/2/2018 xi:52 (#6615216 - in reply to #6614365)
Field of study: RE: Drill bit to hole size question....

North Key Illinois

Actually they are telling you the truth. Go to a machine shop and tell them your dilemma. I recollect yous volition find they apply a bit slightly larger than 1/2" for a 1/2" bolt. JohnW

Posted iii/2/2018 12:03 (#6615248 - in respond to #6614365)
Subject field: RE: Drill bit to hole size question....

NW Washington

You should drill a pigsty a 1/32 or 1/64 larger than the bolt size if you don't desire an interference fit. So for a ane/2 bolt drill a 33/64" hole or a 17/32" pigsty.
A set up of Letter sized bits volition let you finesse things a little better in some cases. littlejo

Posted three/2/2018 12:22 (#6615295 - in reply to #6615248)
Discipline: RE: Drill bit to hole size question....

Big Sky Country

whack it thru with a hammer and you got instant lock nut.

A complete prepare of hammers is very first tool to own....

Pivo

Posted 3/ii/2018 12:42 (#6615337 - in respond to #6614365)
Subject: RE: Drill chip to hole size question....

Montezuma, Ohio

This chart might aid. https://pages.mtu.edu/~suits/misc/tapsizes.html GDAD

Posted three/2/2018 15:55 (#6615642 - in respond to #6614365)
Subject: RE: Drill chip to hole size question....

Northeast Missouri

I always oversize commodities holes unless they are to be tapped or some other special circumstance. In the structural world, code calls for bolt holes to be oversized by ane/16" for steel to steel connections. You don't want any sort of binding between the bolt and the hole, or it can interfere with the clamping action of the tightened bolt, which is what you are trying to achieve. palennn

Posted 3/ii/2018 16:43 (#6615710 - in reply to #6614365)
Subject: RE: Drill bit to hole size question....

North Central Kansas

I've found that twist drill bits generally cut a couple thousandths larger than the actual fleck bore measurement.
The problem with bolt or pin interference is sometimes caused past the chip cutting undersize when breaking thru the reverse side.
This will leave a smaller land that is merely a few thousandths smaller than the rest of the hole. The land can usually be removed with a chamfer bit or maybe a rat tail file.
I generally drill using the same nominal size bit as the bolt. One way to get the bit to drill a little oversize is to grind one flute slightly more than the other creating an off center betoken. This will cause to flake to orbit slightly while drilling and create the oversize hole.
If trying to get a hole that is the same verbal size as the bit starting time drill it with the next size smaller. Then use the on size" bit to follow the hole and act similar a reamer.
I concord that one/32" oversize is about right for nigh bolt holes but sometimes a closer fit is needed.
wht 1

Posted 3/2/2018 17:09 (#6615747 - in reply to #6614390)
Bailiwick: RE: Drill scrap to hole size question....

E. CO, exactly half way between NE and OK

If I desire to drill a 1/two" hole, I use a 1/2" scrap and put a 1/2" bolt in it. If I desire a 1/iv" hole, I use a one/4" bit and put a 1/4" bolt in it. PopC

Posted 3/2/2018 18:01 (#6615824 - in respond to #6615295)
Subject: RE: Drill bit to pigsty size question....

that's how I commonly do information technology , wack it through with a big wrench , then wonder why the nut won' t start
usually tin can't find a hammer , but that's ok any wrench or tool can be a hammer 65_4020

Posted iii/two/2018 18:43 (#6615911 - in reply to #6614365)
Subject: RE: Drill bit to hole size question....

Fundamental Missouri

I'g a machinist so I probably don't know what I am talking nearly. But a i/2" bit shouldn't drill a hole to fit a 1/ii" bolt. I typically drill .015"-.030" over depending on the job.

If a drill bit is drilling oval holes it'south not perfectly perpendicular to the role to isn't set upward rigid and is going in at an bending or wobbling.

Also any bit that has been resharpened volition drill holes larger than the fleck diameter because as it gets ground down the webs get thicker.

7150

Posted 3/2/2018 21:04 (#6616240 - in reply to #6614390)
Subject: RE: Drill bit to hole size question....

+1 for Clarkburn

Edited by 7150 3/2/2018 21:05

Offroadnt

Posted three/3/2018 07:15 (#6616695 - in reply to #6614971)
Subject: RE: Drill bit to pigsty size question....

Southern Alberta Canada

jimgen - iii/2/2018 08:48

Off road

The difference in washers is U.s. vs SAE class.

If you lot buy US form many times these washers will fit the next size up. Most farm stores and chain stores only sell US clase.

SAE class are smaller in OD than United states of america but fit the commodities size.
Also in SAE you tin buy different thickness washers.

We do not use United states of america washers for annihilation unless
building wood crates or skids.

I can only wish for washer selection similar you accept down there, even our SAE washers seem to be mode oversized, I really don't get it. I suppose I could try to order washers simply it's one of those items you don't think about much until you become to use them.

A flat washer isn't rocket science, they stamp out a billion of them a twenty-four hour period, why not build the actual correct size dice?

Offroadnt

Posted 3/3/2018 07:xix (#6616706 - in answer to #6615824)
Subject: RE: Drill bit to hole size question....

Southern Alberta Canada

PopC - three/2/2018 17:01

that's how I unremarkably practise it , wack it through with a big wrench , so wonder why the nut won' t start
usually tin can't find a hammer , only that's ok any wrench or tool can be a hammer

Only thinking, the threads on a bolt are usually smaller than the shank (at least mine are) you never damage the threads with a size on size drill bit hole?

D6Joe

Posted 3/3/2018 fifteen:37 (#6617531 - in reply to #6614365)
Subject: RE: Drill fleck to pigsty size question....

east fundamental ND

I am starting to play around with machine tools and micrometers in my shop. It is a whole unlike world of measuring. Calling something "1/2 inch". And having it measure out 0.500" is two different things. My optics have been opened, and a lot of head scratching and math has been the result.

Edited by D6Joe 3/3/2018 xv:40

65_4020

Posted 3/3/2018 17:32 (#6617715 - in reply to #6617531)
Discipline: RE: Drill fleck to hole size question....

Central Missouri

I confuse people a lot because I never write numbers as a fraction, always as decimals. My dad is one of them. I had an erstwhile machinist I used to work for tell me ane time fractions are for carpenters and welders, machinists use decimals. palennn

Posted 3/iv/2018 xvi:23 (#6619773 - in respond to #6614365)
Subject: RE: Drill bit to pigsty size question....

North Central Kansas

1 advantage of drilling size on size (one/2" bit for 1/ii" commodities for example) is that the bolt sort of acts like a dowel pin.
It not only ensures more precise alignment of the mating parts just tin can also forestall the start of whatsoever move that over time will wear out the holes.
Rod Maker

Posted 9/8/2018 12:xiii (#6976799 - in answer to #6619773)
Field of study: RE: Drill bit to hole size question....

Westport, IN

Merely now you lot get to watch the radius of the shoulder head connexion. Without a washer, the radius will seat and become loose.