lathe part supplier asking questions over my head…help

[Chris TickTockParticipant @christicktock]

hi I was asking my Sherline parts supplier if he supplies various lathe cutters for metal including a radius cutter. He has responded with right hand , left hand and boring cutter but no radius cutter . He states it is better to grind your own and do I have a radius gauge.

my question is: What is a radius gauge?

regards

Chris

[Chris TickTockParticipant @christicktock]

[RobCoxParticipant @robcox]

Hi Chris,

Not surprised they don't stock such a thing. There's an infinity of possibilities for the radii and whether it's to cut an internal or external radius, hence the suggestion of grinding your own.

A radius gauge is kind of like a feeler gauge, but instead of the thickness being the calibrated dimension, it will have either a protrusion or cutouts with a specified radius. To use it, you'd grind a curve on your tool then hold it in the cutout in the gauge up to the light to see how well the tool matches the gauge curve and grind the tool to adjust as required.

Rob

[Chris TickTockParticipant @christicktock]

Thanks Rob, its time to buy a set/

Chris

[JasonBModerator @jasonb]

You don't need to buy one, for a concave gauge just drill a hole twice the radius you want in something thin and then cut/file away the waste until you have a 1/4 circle left to use as a gauge.

For a convex gauge just use a drill who's diameter is twice the radius and offer that upto your tool.

If you are wanting to round over a corner or add a concave mounlding to a corner then it is also possible to hold a round over milling or router cutter or in the toolpost and use one of the flutes to cut with.

For tools with a concave cutting edge you can also just drill a hole in some gauge plate and then saw/file away half to form a bead or 3/4 to form a round over cutter and then harden.

[VicParticipant @vic]

Perhaps of interest.You can use a boring head for ball and radius turning etc.

**LINK**

[Chris TickTockParticipant @christicktock]

Great posts guys thanks

Chris

[larry phelan 1Participant @larryphelan1]

I bought two sets, convex /concave from China for pence [or cents ! ]

Very simple to use.

[Chris TickTockParticipant @christicktock]

Hi I have just bought 3 quality sets off Ebay for £10 delivered. having done that I have a small confession to make I get you can measure the radius of an object but can they be used to create a form cutter/

Chris

[Jeff DaymanParticipant @jeffdayman43397]

You could use them to mark out a piece of tool steel to make a form cutter, but not likely they will be usable to cut metal – they are NOT meant for that – they are an inspection tool.

Please re-read Jason's post above – he's told you how you can make radius form tools already.

[Chris TickTockParticipant @christicktock]

Thanks alot guys yes get the radius gauge is to see if you have made the radius correctly. Surely the gauges could be used to check the form tool msade as Jason's method is correct as well as testing the machined work is also correct.

Regards

Chris

[JasonBModerator @jasonb]

I would imagine that most radii shown on clocks which seems to be your intended use would be more for decorative purposes and more often that not would be turned freehand with a graver than using a form tool so "look " is more important than absolute accuracy.

Even grinding to a printed template that can be stuck to the tool or cut out and used to mark the tool will do, this picture shows a tool in th emaking, with a hole drilled as I mentioned above to form the half round then the printed template has been used to mark th erest of the shape.

The completed tool in use

And completed part

And a bit of big boy 5" dia hand graving

[Author]

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