Thursday, 23 October 2008

Milling in the lathe

As mentioned in previous article about compound tables and cross vices, I'm interesting in milling to get better results than manual filing for my T-nuts.

I realised that because of the small side of these nuts it would be possible to mount them in the tool holder. So I added an extra screw in the tool holder, something I'd been planning to do anyway as I have some shorter lathe tools and it gives me more rigidity when when using those.

I'd bought a small end mill at the Ascot model engineer show and did some test cuts with that. Trying to machine more than about 0.2mm caused the mill to slip in the lathe jaws. Solutions for that problem would be to get a proper collet system to hold the milling cutter but I chose the option of simply trying to cut less metal. I raised the height of the tool post slightly with some circular shims as there was not sufficient adjustment if I only shimmed the item in the tool post. The result as you can see from the picture below is a simple yet sturdy setup.

Milling in the Mini-Lathe

The T-Nut was roughtly sawn to size and then milled. The results are a lot better than my filing attempt but I do need the practice of making a few more...

T-Nuts Filed vs Milled

It is also possible to attach a angle plate to your crossslide and then a vertical slide and a vice. Care needs to be taken not to produce an off balance solution as it won't be sturdy and will put additional strain on the dovetails. Here's an example milling attachment from Varmit Al where he's pushing it to the absolute limits.

References:



http://www.armurerieduroi.com/pages/lathe/lathe_milling.html
http://www.astronomiainumbria.org/advanced_internet_files/meccanica/easyweb.easynet.co.uk/_chrish/tmilling.htm
http://www.vintageprojects.com/machine-shop/lathe-milling-attachment.html
http://www.saunalahti.fi/~animato/transferseu/milling.html from machinist and animator Jan-Eric Nyström, Helsinki, Finland

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