# LMS thread hole chart re metric



## PeterT (Oct 21, 2021)

I just discovered something about many of the thread hole charts when it comes to their 'metrification'. Little Machine Shop for example. Not picking on them because others appear to do the same. I was wondering why my CAD drawings rarely aligned to the LMS wall chart in my shop. In my CAD program I select the hole from a drop-down which also specifies the standard. I can convert dimensions between imperial & metric & assumed that was the root of the issue. 

For example a clearance hole for M3 fastener, all 3 common metric standards (ANSI, ISO & DIN) provide 3 categories: Close, Normal & Loose. All 3 have the same dimensions which correspond to mm drills in 10ths as shown in the spreadsheet. The LMS chart has only 2 categories, Close & Standard, neither of which correspond to the metric standards. And the substitute drills are kind of somewhere in between. This might not make any difference to your day to day work, but just be aware. I think its meant to be helpful to N-Am/Imp tooled shops to get something close.


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## PeterT (Oct 21, 2021)

If anyone comes across a chart with all 3 metric categories (as opposed to an IMP conversion chart or only 2 categories) I'd be interested to know.


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## RobinHood (Oct 21, 2021)

Hi Peter,

This might be what you are looking for (from “Tabellenbuch Metall, section 5.2 Schrauben (bolts), pg. 220):






Durchgangslöcher für Schrauben = through (clearance) holes for bolts
Gewinde = thread
Reihe = column in the table
fein = fine (close) tolerance per H12
mittel = medium (normal) tolerance per H13
grob = coarse (loose) tolerance per H14


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## PeterT (Oct 21, 2021)

Interesting. Is that like a European version of our Machineries Handbook?
I would have thought this would be readily available online info. I even have a table in my Machineries Handbook (25th Ed)  

My EX-favorite site went into adbocker hostage mode, grrrr...
https://www.gewinde-normen.de/en/index.html


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## RobinHood (Oct 22, 2021)

PeterT said:


> Is that like a European version of our Machineries Handbook?



Yes, it is. Stefan Gotteswinter refers to it occasionally in his videos. It is available for purchase here (both in German and English):

https://www.europa-lehrmittel.de/t-1/mechanical_and_metal_trades_handbook-3579/

The table is also available in the Machinery’s Handbook. In the 29th edition it is Table 7 “British Standard Metric Bolt and Screw Clearance Holes BS 4186: 1967” on page 2034.


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## Susquatch (Nov 18, 2021)

Sorry to be so late chiming in. I use a drill/tap chart app on my android phone. It has lots of other threading info too. 

The app is called "Tap and Drill Chart Calculator". It has metric and imperial and lists fits as well as material and also shows next best fit.


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## Everett (Nov 18, 2021)

Never used the Tallenbuch Metall, but have the 29th MH and used the charts in it a few times for threads. For most of my fit work, because even though I can do the wire calculation but am a tad lazy, I use the Theoretical Machinist calculator. Handy for odd ball threads if you need to use them. 





						UN imperial screw thread calculator
					






					theoreticalmachinist.com


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## Everett (Nov 18, 2021)

Here's the SI version:




__





						Metric screw thread: M Profile calculator
					






					theoreticalmachinist.com
				




Doesn't have as many features but I think they're still developing this side of it.


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