MadModder

The Shop => Tools => Topic started by: piper1 on March 15, 2014, 03:16:42 PM

Title: Which is the correct lathe cutting tool to use
Post by: piper1 on March 15, 2014, 03:16:42 PM

Hi I was wondering if anyone could advise on which is the correct to tool to use.

I want to be able to cut and angle of 30 degrees on a 30mm Brass round bar.

I have randomly tried a  couple of cutting of tools and found it pretty difficult to achieve and the quality of the cut is poor.

Thank you
Kev

Title: Re: Which is the correct lathe cutting tool to use
Post by: Jonny on March 15, 2014, 04:43:47 PM

Everyone will have their own personal choice but assuming you have done the basics brass is one of the easiest to machine with any tip angle and shape, that's why its used plus no finishing.
I'll put money on it you have movement or flex.

Title: Re: Which is the correct lathe cutting tool to use
Post by: Manxmodder on March 15, 2014, 04:50:48 PM

Quote from: piper1 on March 15, 2014, 03:16:42 PM

Hi I was wondering if anyone could advise on which is the correct to tool to use.

I want to be able to cut and angle of 30 degrees on a 30mm Brass round bar.

I have randomly tried a  couple of cutting of tools and found it pretty difficult to achieve and the quality of the cut is poor.

Thank you
Kev

Hi Kev, I tend to agree with Jonny that flex of the workpiece or tool is causing your poor finish(is it chatter marks you're seeing ?)

Alternatively try adjusting your top slide around to the desired angle and take a facing cut with a sharp tool.....OZ.

Title: Re: Which is the correct lathe cutting tool to use
Post by: BaronJ on March 15, 2014, 05:09:59 PM

Hi Kev,


I too agree with Jonny and Manxmodder.  The only time I got chatter turning brass was when I got the tool hight wrong and it was too far out from the chuck.  I should have used a steady.  But that's all part of the learning curve. :hammer:

Title: Re: Which is the correct lathe cutting tool to use
Post by: rick barnes on March 15, 2014, 08:40:16 PM

Brass can be a tough teacher. 

Title: Re: Which is the correct lathe cutting tool to use
Post by: Fergus OMore on March 16, 2014, 05:27:53 AM

Brass is one of the easiest metals to turn. It requires no lubrication and no fiddly about with top rakes to grind and hone. So a piece of square hss tool only needs a lick on a bit of flat glass or plate and a bit of Brasso or an oil stone.

Classically, brass was turned with a diamond shaped graver on a hand rest which-if you think about it, was a tangential tool.

I learned with a bit of broken window glass on wood. Not everyone's thing but we had no choice.

Norman

Title: Re: Which is the correct lathe cutting tool to use
Post by: TLGriff on March 16, 2014, 01:38:46 PM

I would use an ordinary right hand turning tool set perpendicular to the 30º surface. I assume you'll be using the compound to generate the angle? Free machining brass is easy to turn, but some alloys can be difficult to achieve a good surface finish. Other than getting the angles right on the tool and making sure it is on center, be sure to stone the cutting edges and the radii on the tip.

The following link is to a reference sheet on my website showing how to grind such a tool, along with the proper clearance angles.

Right Hand Turning Tool (http://tomstechniques.com/reference/)

Hope this helps.

Tom

Title: Re: Which is the correct lathe cutting tool to use
Post by: piper1 on March 16, 2014, 03:27:38 PM

Thank you so much for all the support, i really do appreciate the help.
I’m going to try and eliminate possible causes by listening to your advice.

First by reducing the length of the cutting tool in the tool holder.
Then by changing the cutting tool tip.

Fingers crossed for a better finish.

Thanks
Kev