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Turning a radius on a lathe
Furyous - 16/8/12 at 09:19 AM

I've been getting the hang of my lathe and I've already made about $700 worth of tools for work in just a few weeks, with huge improvements over some of the old tools we were using.

Something I would like to improve on is turning a smooth radius. The tools I'm making are a cup to hold the base of a bottle steady. At the moment I'm either using a right angle base or guessing a rough slope near the shape of the bottle base. Ideally it would match the radius of the edge of the bottle base. I can't seem to find much online other than some home made looking rotating tools to replace the fixed tool post. Ebay just has a couple of tools available from America with shipping three times the cost of the item.

Am I missing something or are the things I'm looking for really that uncommon?


daviep - 16/8/12 at 09:38 AM

Is it not possible to grind a tool to the correct radius?

Cheers
Davie


liam.mccaffrey - 16/8/12 at 09:56 AM

I have one of linky for sale. You could extend the cutting tool out past the pivot point and cut internal rads. I havn't tried this though!!

Also Hemingway sell this kit. linky

You might be better with a form radius cutter for very small rads though.

[Edited on 16/8/12 by liam.mccaffrey]


robocog - 16/8/12 at 10:02 AM

Ball turning tool
http://bedair.org/Ball/ball.html

http://www.machinistblog.com/free-plans-ball-turning-tool-post-for-the-7x-mini-lathe/

Cutting tool can be reversed to make a cup / socket turning tool

Looks simple enough to make and use ....I have been meaning to make one for a few years but not got 'round' to it yet...LOL

Dividedheads fab vids showing them in use....

http://www.youtube.com/watch?v=tbvOb-tTNyc&feature=channel&list=UL

http://www.youtube.com/watch?v=s_KRElCauTM&feature=related

Regards
Rob


mad4x4 - 16/8/12 at 11:58 AM

What about this - Build yourself one


40inches - 16/8/12 at 02:06 PM

quote:
Originally posted by daviep
Is it not possible to grind a tool to the correct radius?

Cheers
Davie


That's what I did, doesn't take long.


mcerd1 - 16/8/12 at 02:55 PM

quote:
Originally posted by 40inches
quote:
Originally posted by daviep
Is it not possible to grind a tool to the correct radius?

Cheers
Davie


That's what I did, doesn't take long.

thats what I've always done too, but the links above have got me thinking about building a new tool.....


owelly - 16/8/12 at 03:40 PM

I've often turned stuff using a pointer mounted in the back of the tool post, running on a profiled template. A bit like a key cutting machine. With a bit of patience, it works very well and certainly better than free hand!!


theprisioner - 16/8/12 at 06:14 PM

Just some stepper motors + software

http://youtu.be/JvU0Uo-ntZw


Furyous - 16/8/12 at 06:46 PM

Thanks for the replies.

The trouble with the home made ball turning tool is I would need a mill to cut the slot in the centre, which I don't have.

I'm currently using cutting tools with replaceable tips but I could try grinding my own tools. The problem with that is I would spend a lot of time grinding a cutting tool that would only be suitable for one type of bottle/cup. The rotating tool post type seems like it would be easier to adjust for different jobs. But then I wouldn't be able to turn it very deep in the cup before it hits the rim of the cup.

I'll have a go at grinding some cutting tools.


907 - 16/8/12 at 09:32 PM

I made this.
Just a brake clevis and a cap head screw with a grub screw inside the head to hold a tool.

Paul G
Description
Description


daviep - 16/8/12 at 10:06 PM

quote:
Originally posted by Furyous
Thanks for the replies.

The trouble with the home made ball turning tool is I would need a mill to cut the slot in the centre, which I don't have.

I'm currently using cutting tools with replaceable tips but I could try grinding my own tools. The problem with that is I would spend a lot of time grinding a cutting tool that would only be suitable for one type of bottle/cup. The rotating tool post type seems like it would be easier to adjust for different jobs. But then I wouldn't be able to turn it very deep in the cup before it hits the rim of the cup.

I'll have a go at grinding some cutting tools.


I would never claim to be able to grind tools "properly" but it's very easy to grind them to an adequate standard.

Do you have coolant on your lathe? If not then something to watch if you are self taught and always used carbide tipped tools is that HSS will not tolerate being run too fast - instant bluntness, a lesson I'm still learning (or not as the case may be)

Cheers
Davie


Furyous - 17/8/12 at 04:53 AM

quote:
Originally posted by 907
I made this.
Just a brake clevis and a cap head screw with a grub screw inside the head to hold a tool.

Paul G
Description
Description



That looks like something I could cobble together myself. It's also small enough to get inside the cup. I just need to find some clevises somewhere.


Grinding my own tools would probably be cheaper than replaceable tips in the long run anyway.


907 - 17/8/12 at 06:06 AM

quote:
Originally posted by Furyous
quote:
Originally posted by 907
I made this.
Just a brake clevis and a cap head screw with a grub screw inside the head to hold a tool.

Paul G
Description
Description



That looks like something I could cobble together myself. It's also small enough to get inside the cup. I just need to find some clevises somewhere.


Grinding my own tools would probably be cheaper than replaceable tips in the long run anyway.





Ebay? or a trailer spares site?

eBay Item


Furyous - 17/8/12 at 06:15 AM

I'm in New Zealand so it's not as easy as going to eBay. We have TradeMe here, which is like eBay in 1998. I'm not all that familiar with local shops so I'll have to look around for them but I'm sure they're available.

On a related note, apparently a C spanner is a specialist item and very few places sell them here. I still haven't found anyone that actually sells them.


mcerd1 - 17/8/12 at 07:12 AM

sounds like your going to need to find someone over there with a milling machine and/or a waterjet cutter to make all the tools you need


907 - 17/8/12 at 07:35 AM

quote:
Originally posted by Furyous
I'm in New Zealand so it's not as easy as going to eBay. We have TradeMe here, which is like eBay in 1998. I'm not all that familiar with local shops so I'll have to look around for them but I'm sure they're available.

On a related note, apparently a C spanner is a specialist item and very few places sell them here. I still haven't found anyone that actually sells them.




You could put an end milling tool in the 3 jaw chuck and the square bar in the tool post
and mill the slot straight into the bar.

You wanted to play with your lathe.


In the past I've made end cutting tools from the shaft of a broken tap.
(never throw a broken tap away)

Paul G