# Center drills!



## bradbyname (Jun 19, 2011)

So, needless to say im new to turning, and learning my way around the lathe 

Knowing that i need to drill a hole for a dead center, i went shopping for a center drill. BS1,BS2,BS3...... ok - I understand why we need all the different sizes, but im a bit stumped as to which one i should buy for drilling a hole for the dead center!

Anyone who is kind enough to shed some light on this would be greatly appreciated

Kind Regards


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## Tin Falcon (Jun 19, 2011)

> im a bit stumped as to which one i should buy for drilling a hole for the dead center!


that is why it is best to have a set. there is not formula but more rules of thumb. when you are turning on centers the dead center or live ball bearing center in the tail stock supports the work. Small diameter work requires a small center drill. larger and soft material needs a larger size. the general rule of thumb is to use the smallest size that will support the work. If you have to, make the work longer use a bigger center drill for support then trim to length on the lathe when done turning. This is best done with a specialty ground tool with a half center but can be don with a regular center. 
Tin


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## bradbyname (Jun 19, 2011)

Ah fair enough, I shall order a range of them.

Thanks for the advice, thats certainly cleared it up for me

Brad


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## Tin Falcon (Jun 19, 2011)

Brad if you have not already done so download a copy of army TC 9-524 
http://www.metalworking.com/tutorials/army-tc-9-524/9-524-index.html
at the very least read chapter 7 lathes . it will cover many of the basic lathe operations. 
and a lot more info here 
http://www.homemodelenginemachinist.com/index.php?topic=9413.0
Tin


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## bradbyname (Jun 19, 2011)

Many thanks Tin
Looks like a wealth of information there.

I have watched the AGI milling and lathe series which i have on DVD but i either overlooked the part on center drills (most likely) or the different sizes were not mentioned (unlikely), but more reading material the better


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## xo18thfa (Jun 20, 2011)

About 30 years ago I bought a big handful of #3 size from an old surplus yard in Minneapolis. That's the only size I've ever used. Also bought pocket full of 2 x 56 taps. It's the standard in my shop. It's funny how your machinist path gets locked for you in some ways.


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## Omnimill (Jun 20, 2011)

And to confuse you even more, I like the bell type but either will do ;D

http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Centre-Drills

Vic.


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## bradbyname (Jun 20, 2011)

Thanks for the replies Bob & Vic

I went for these ones in the end: 
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130432503622&ssPageName=STRK:MEWNX:IT

and then ebay got the better of me:
and one of them






and one of these:





and maybe some of these too:





and then thought i need one of these:





and then the weekend occured to me that i have no plans:











Rounded off with some of this:







Curse you ebay.... i only went on there for a centre drill set ??? : (but i got a few new toys :big: )


Brad


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## xo18thfa (Jun 21, 2011)

The drill chuck and live center are definite "must have" for the lathe. I see you are in the UK, what screw thread is used mostly now? BA or metric?


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## bradbyname (Jun 21, 2011)

Predominantly Metric. i think (but dont quote me) that BA is mostly obsolete now. Although it may still apply to the smaller threads. I know it is still used in certain applications usually with precision instruments and the like obviously.

Yes i live in the UK, good ol' land of rain.


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## Jasonb (Jun 21, 2011)

BA IS the predominant thread for UK model engineering.

In Industry it is Metric.

Personally I manage with No 1 & 2 centre drills and my models are a bit larger than a lot here, couple of long reach ones don't go amiss either. If its just for starting a drill then spotting drills work well and are a littel less fragile.

Jason


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## bradbyname (Jun 21, 2011)

Thanks for the correction, and information Jason


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## gunboatbay (Jun 23, 2011)

A good starting point for answering your initial question is the attached chart. It's in fractions, but can easily be converted to metric.


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## bradbyname (Jun 24, 2011)

Ah, many thanks for that. I have printed it out and put it in my reference book


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## Alchymist (Jun 29, 2011)

I keep several sizes on hand, including #00 for use in this:


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