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  #11  
Old 01-18-2019, 04:16 PM
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What I liked about this chart is the different drill bit choices for percentage of thread.
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  #12  
Old 01-18-2019, 04:21 PM
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Originally Posted by digr View Post
What I liked about this chart is the different drill bit choices for percentage of thread.
I did notice that as well and think it will be helpful as well
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Old 01-18-2019, 05:28 PM
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Originally Posted by digr View Post
What I liked about this chart is the different drill bit choices for percentage of thread.
I liked that as well, I have been using 8 * 11.5 sheets of paper, as the
eyes are getting older they are easier to read than the pocket charts.

I put together the attached chart as well when looking for drill sizes.
Attached Files
File Type: pdf Drill Chart.pdf (46.5 KB, 83 views)
File Type: xlsx Drill Chart.xlsx (30.4 KB, 61 views)
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  #14  
Old 01-19-2019, 12:28 PM
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Originally Posted by terry lingle View Post
It is about 20 X30 and the writing is large enough that my old eyes can read it.
It is also about 50 years old and it has been a long time since I have seen anything at the suppliers. I remember when every supplier had a gimmick give away item sitting on the counter.
Busy Bee still does give away a chart about 2 x 3ft
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Old 01-19-2019, 01:01 PM
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I found this video on charts it prolly not so helpful to you guys who already understand all this stuff but it did give me a much better understanding of use and purpose, So it might be useful to others as well.

https://www.youtube.com/watch?v=wV05WFZnRkE
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  #16  
Old 01-30-2019, 06:50 AM
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Digr... Is there a chart for the drill bit to reamer size I haven't looked for one yet but maybe you could point out one us beginners can understand
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Old 01-30-2019, 01:15 PM
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Originally Posted by MetalWolf View Post
Digr... Is there a chart for the drill bit to reamer size I haven't looked for one yet but maybe you could point out one us beginners can understand
I've never seen a chart for reamer sizes--even Machinery's Handbook doesn't show anything. It's pretty easy to figure out. For up to about 5/16" your starter hole can be about .010" undersize. Anything larger can use a starter hole about .015" smaller than the reamer size. If you happen to be working with real small holes--1/8" or smaller--you can make your starter hole only .005"-.006"...
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Old 01-30-2019, 01:30 PM
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Originally Posted by LKeithR View Post
I've never seen a chart for reamer sizes--even Machinery's Handbook doesn't show anything. It's pretty easy to figure out. For up to about 5/16" your starter hole can be about .010" undersize. Anything larger can use a starter hole about .015" smaller than the reamer size. If you happen to be working with real small holes--1/8" or smaller--you can make your starter hole only .005"-.006"...
Yeah, I was just wondering if there was like a general chart but was watching some YT vids and people were saying basically a general rule of thumb for most holes was 3/16's undersize unless it were smaller holes... although I could be wrong on the 3/16's and he might have been meaning the drill hole
I'd have to go back and watch it again... to be sure

Sorry I'm still trying to get the hang of the measuring in thousands I still have to look at a chart I got off the net to know, But I think my safest bet is to ask here on the forum before I screw something up I have worked hard on...
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  #19  
Old 01-30-2019, 02:10 PM
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Drill bits make holes that are not round straight or accurately sized they are fine for putting a bolt through and often good enough for most other purposes.
If you need better accuracy you move to more accurate finishing tools.
By definition a 5/16 drill bit must make a hole at least 5/16 in diameter but which may be larger than 5/16. If you want to see how much oversized a drilled hole can get just sharpen a bit so that the point is almost at one edge.
Reamers allow very accurate holes but work best when the drilled hole you are reaming is as close as possible to the desired finished size. while the standard drill index has 29 bits between 1/16" and 1/2" nominal there are actually about 150 drill sizes available in that range when you add up all the different sets available.
standard 29
number 60
letter 26
metric drills 25
quick total 140 different drill sizes in specific indexes.
A few of these bits are the exact same specification 1/4 inch and "F" letter drill come to mind.
With this many increments available selecting the proper pilot drill for a reamer is pretty easy.
This leaves the whole drill range above 1/2 inch not covered.

Note that I am only detailing drill bits for use on metal here.

My own drill collection goes to 1 7/16 and above that i can bore to about 15 3/4 on my lathe.

Reamers are only used where very close tolerances are needed and are relatively expensive so while I own all of the above drill sets I only own reamers that I have needed or those I have acquired as part of bulk purchases.
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Old 01-30-2019, 03:17 PM
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Quote:
Originally Posted by terry lingle View Post
Drill bits make holes that are not round straight or accurately sized they are fine for putting a bolt through and often good enough for most other purposes.

If you need better accuracy you move to more accurate finishing tools.

By definition a 5/16 drill bit must make a hole at least 5/16 in diameter but which may be larger than 5/16. If you want to see how much oversized a drilled hole can get just sharpen a bit so that the point is almost at one edge.

Reamers allow very accurate holes but work best when the drilled hole you are reaming is as close as possible to the desired finished size. while the standard drill index has 29 bits between 1/16" and 1/2" nominal there are actually about 150 drill sizes available in that range when you add up all the different sets available.

standard 29

number 60

letter 26

metric drills 25

quick total 140 different drill sizes in specific indexes.

A few of these bits are the exact same specification 1/4 inch and "F" letter drill come to mind.

With this many increments available selecting the proper pilot drill for a reamer is pretty easy.

This leaves the whole drill range above 1/2 inch not covered.



Note that I am only detailing drill bits for use on metal here.



My own drill collection goes to 1 7/16 and above that i can bore to about 15 3/4 on my lathe.



Reamers are only used where very close tolerances are needed and are relatively expensive so while I own all of the above drill sets I only own reamers that I have needed or those I have acquired as part of bulk purchases.


My selection of reamers is the same, a mix of stuff I’ve picked up over time.

With reamers there’s also oversize/undersize options, depending on what you are trying to do.

Also, reaming a hole follows the hole that is drilled, regardless if it’s right or not. Boring can move a hole, as it doesn’t follow the previously drilled hole.

I’ve had to drill, then bore to ensure location, then ream to finish the size.


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