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JIG - Find the absolute centre every time

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Treeesa

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Finding the centre of a blank without putting in a small drill bit first is particularly important for segmented blanks that will show any errors can be quickly solved using the trick.

* Put a bit of plasticine onto the drill bit
* Put in a very small drill or a needle if you can find one ( I couldn't!)
* Run the drill and gently touch the small drill bit with a file, spanner or anything with a straight edge
*This will now show the centre of the drill bit in the chuck
* Bring the workpiece into line and clamp

There may be other ways but this one works for me
 

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T

Treeesa

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The plastic bottle is in the distance and looks like it's touching the plasticine but it's just an optical illusion - couldn't have done it if I'd tried
 
Woody

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Lons said:
Interesting Andy but if you use lip & spur bits with a sharp centre point you don't need to do that.
Click to expand...

I was just about to say that Bob or if you haven't got one do what we used to do and nd I still do just touch the wood lightly with the drill running and the mark will show how close you are to the centre then make your adjustments to te cross vice as needed
 
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Treeesa

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Walter said:
Looks to me like a bit of a faff to do something that could easily be done just by lining up a centre drill or a pointed rod held in the chuck. But each to his own.
Click to expand...

The tip comes from engineering where the accuracy needs to be far higher than pen turning and you can get within a couple of thou using a needle - it was aimed at those who do segmenting and want to be at the absolute centre to avoid spending hours making a blank only to see it turn off centre. But you're quite right when you know it all you don't need any tips
 
silver

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I agree that it's one way, if it works for you then continue to do it.


Walter said:
Looks to me like a bit of a faff to do something that could easily be done just by lining up a centre drill or a pointed rod held in the chuck. But each to his own.
Click to expand...

Just what I thought when I saw it TBH Walter. But I'm sure Andy has perfected it and if it works then it's right for Andy..
 
bellringer

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cookie21 said:
Just drill blanks using a lathe & chuck, the centre point is there auto with no hassle
Click to expand...

That were you Wong it will very likely be off centre if it a square blank that not been cut 100% square


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bellringer

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Walter said:
No way I know it all or think I do Andy, I just think there are easier and more reliable methods such as those I described. If it works for you fine. No need to take the hump if it doesn't suit everyone.
Click to expand...

They are not more reliable you should never really use centre drill to line things up it not 100 % accurate the method above is


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Treeesa

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Walter said:
No way I know it all or think I do Andy, I just think there are easier and more reliable methods such as those I described. If it works for you fine. No need to take the hump if it doesn't suit everyone.
Click to expand...

Walter, no offence taken but perhaps I should have said if you can't centre punch the blank to be be sure of getting the pointed rod centred then this will allow you to find the absolute centre.

Truth is this is a production tip that speeds things up by having to only open the chuck once. Over one hole it may not be needed but try 50 holes in different locations- I'd be making the tea while you were still faffing with your rod and fiddling with your chuck


It's alright for you buggars that retired - I need to save every minute :funny:
 
Walter

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bellringer said:
That were you Wong it will very likely be off centre if it a square blank that not been cut 100% square
Click to expand...

I agree although a two jaw pen blank chuck will limit that. It is also dependent upon the accuracy of and the amount of play in your tailstock which on woodturnng lathes is not always that wonderful.

bellringer said:
It basically this MP Direct by MP Tools | For Tools and Spray Equipment| Silverline Wiggler & Centre Finder Set
Click to expand...

Thanks for the link Alex. I was aware of these tools but I still think it is way too much faff for drilling pen blanks, even segmented ones. And it won't stop your drill running off and following the grain which is one of the biggest problems with wooden blanks.
 
bellringer

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Walter said:
I agree although a two jaw pen blank chuck will limit that. It is also dependent upon the accuracy of and the amount of play in your tailstock which on woodturnng lathes is not always that wonderful.



Thanks for the link Alex. I was aware of these tools but I still think it is way too much faff for drilling pen blanks, even segmented ones. And it won't stop your drill running off and following the grain which is one of the biggest problems with wooden blanks.
Click to expand...

Buy good quality drill and they will go straight


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