# Modified lathe centers ....



## toolznthings (Apr 25, 2015)

Modified live centers for turning small diameter work that need support and clearance for the lathe tool.
The larger center in the picture was disassembled and the bulk of the material behind the center point was turned back. Carbide cutting tool was able to handle the hardness. The original tip was left intact. ( lower r.h. view )
The two smaller centers use a ball bearings and new shafts with the center point were made. These are the easiest to modify since the shaft is supported by ball bearings, not needle bearings like the larger heavy duty center.The tips were case hardened. With careful setups the centers run true without the need to grind. The extended length gives room between the tail stock quill and the insert tool holder that I use.


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## Swifty (Apr 25, 2015)

Very nice job, I have a centre similar to this http://www.machineryhouse.com.au/C063 with interchangeable tips. I have also made several extended inserts to suit various applications.

Paul.


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## toolznthings (Apr 25, 2015)

Hi Paul,

Actually the center at the top of the three pictured was an interchangeable point type. I took a chance on the quality from where I bought it. Not good at all, so it became the donor for the modification. Worked out well in the end.

Brian


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## Swifty (Apr 25, 2015)

Brian, your post has reminded me that I need to make some more centres for my interchangeable tipped one. Only notice how worn the current ones are when I go to use it.

Paul.


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## goldstar31 (Apr 26, 2015)

I have quite a few more centres which may be of interest.
The first is to mention that there is or was a 'soft centre' which went into the headstock end and was machined ACCURATELY each time work between centres was carried out. 
The second( which I use a lot) is a half centre which enables machining to go- almost to the 'hole'.

Obviously, most of us will have a single or rotating centre and this needs little mention. However, I have 'female' centres which are useful and can run ball bearings sandwiched between them and the work. Very useful and easily made.
I have a couple of ' odd fellows' which might be of interest. The first is a 'waisted' cone whilst the second has 4 flats which will cut an off centre hole into line. We all make mistakes and I'm no exception.

Following Swifty's comments, hard worn points can often be restored with a diamond nail file. 

I also have a rotating female( Oh yes) hollow centre or two for drilling ball handles. 

For those with a adjustable boring bar that fits the tailstock, you can do quite nice tapers by swapping the cutting end for a centre.

Hope the hints are useful


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## Blogwitch (Apr 26, 2015)

Just a little note with no detrimental comments to the original and previous posters.
Well before rotating centres became affordable to the great unwashed, we used to use half centres (carbide tipped if you could afford one). In fact it was only last weekend that I was using one to turn down a 12" long by 5" diameter piece of ali bar to help make a 'cat' chuck. I had to face the end and turn the outside down to 3.75" (so it would fit in my fixed steady). I would have used a fixed steady, but mine wasn't large enough to hold 5" diameter, so had to revert to a tailstock centre.
What modern day model engineers don't realise is that a 'solid' centre is a lot more rigid that a ball raced one, it just takes a bit of careful use to use one and if I had used a rotating centre, I could almost guarantee that I would have run into some sort of offset problem during the time it would have been in use.
Don't get me wrong, I use rotating centres myself, but only for very light cutting, I always revert back to the 'old methods' when a bit of white knuckle work is required. 
Besides, they cost only a small percentage of a rotating centre. So if you can't afford one of the latest rotating ones, a solid one will get you there just as well.
BTW, I find that Copperslip grease is ideal for lubrication if you don't go too fast (it is used in car brakes, so can stand a fair bit of generated heat), as all of you are aware that solid centres require lubrication in use. I also use it for my lathe steady tips as well.

John


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## goldstar31 (Apr 26, 2015)

John

Agreed but don't forget to mention that adjustment to centres has to be made as the work heats up. 

Actually this 'cat chuck' construction does deserve a description. I was eyeing up a Keats angle plate to make. I'd got a Mig again and a donation of some hollow section steel tubing ex- a coffee table and thought that it would be 'interesting' If all failed, I had an old satellite dish bracket.

Certainly a cat chuck is often the answer to a lot of awkward holding problems. 

Thank you. 

Norman


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## Swifty (Apr 26, 2015)

Come on guys, I googled Cat Chucks and only came up with pictures of pretty girls or Chuck Norris. I've never come across this term before. As one infamous Australian politician once said "please explain".

Paul.


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## goldstar31 (Apr 26, 2015)

Try 'cat head' chuck. 

Basically( John?) the cat head chuck is the sort of box -round or square that goes on a face plate. Lots of bolts where you need them and if push comes to shove, bang in a set of wedges.

I got my knuckles rapped one day because I set some job or other in one- but with a glass fibre resin as the wedge.

Perhaps John will oblige with his own variant on a theme.

Cheers

Norman


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## Blogwitch (Apr 26, 2015)

Just a quickie C-o-C to show you what the one that is being made here is like. It will eventually be used for holding a breech and barrel for an air rifle.







I absolutely abhore any form of firearms, so please don't ask any further  questions on that subject. I am just trying to explain what a Cat chuck is, an easy method of holding something out of the ordinary.
I wouldn't normally do things like this but a friend is in dire need.

John


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## Swifty (Apr 26, 2015)

Thanks guys, I googled Cat Head Chucks as recommended and saw the pictures.

Paul.


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## Blogwitch (Apr 26, 2015)

I forgot to mention that the one that is being made here will have a backplate mounted to it so will be a permanent chuck rather than a loose tube for use with a steady.
Certain gun lathes come complete with a cat mounting on the back of the spindle for holding irregular shaped long objects through the spindle bore or for holding long stock so that it doesn't flail about. When eventually I fit an electronic speed control and 3 ph motor I will do the cat mod on my spindle at the same time.

Sorry to have hijacked your post to explain a few things.

John


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