The other day I wanted to turn some little thumbscrews as shown in the drawing. I ground a little bullnose-looking form tool to make the neck. It worked fine for that cosmetic feature, but it made me wonder how you'd grind a similar tool if getting the shape exactly exactly right was more important. Any hints? Is it simply a matter of going slow and being careful?
-- Russell Mac
Tool Grinding Question
Re: Tool Grinding Question
There are form dressers available for those who have need, but they're pricey.
A comparator helps when grinding to close tolerances, as does good vision. With care, a form can be ground within a thou or two by hand. I generally use my Starrett radius gauges for the task and have been known to make a custom radius with a divider, scratching through thin brass shim stock. Any port in a storm.
H
A comparator helps when grinding to close tolerances, as does good vision. With care, a form can be ground within a thou or two by hand. I generally use my Starrett radius gauges for the task and have been known to make a custom radius with a divider, scratching through thin brass shim stock. Any port in a storm.
H
Wise people talk because they have something to say. Fools talk because they have to say something.
Re: Tool Grinding Question
I know it's not practical advice but I've been having great success with my fiber laser. I mark the top of the blank and grind up to it, then final dress it. You could try doing something similar with layout dye and a scriber.
Vision is not seeing things as they are, but as they will be.
Re: Tool Grinding Question
So no real magic, I guess. Thanks, guys.
-- Russell Mac
-- Russell Mac
Re: Tool Grinding Question
In your case a .150 drill blank / hard pin. Mount it @ 10-12 degrees rake in a square blank. Did this many times and it will cut.
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Re: Tool Grinding Question
This is more for completeness than in any way disagreeing with you, but if you mount it like that, you are no longer turning a circular arc, but an elliptical one.
With a nearby CAD, you could overlay the two and see what the actual difference is, no doubt extremely small.
Re: Tool Grinding Question
You are correct, but for knob good enough. Being old school hand grinder it would be HSS + 5 minutes on a bench grinder. Becoming a lost Art with insert tools. Just giving the OP something to ponder, if not comfortable with hand or ? Grinding.arborist wrote: ↑Mon Oct 03, 2022 7:20 amThis is more for completeness than in any way disagreeing with you, but if you mount it like that, you are no longer turning a circular arc, but an elliptical one.
With a nearby CAD, you could overlay the two and see what the actual difference is, no doubt extremely small.
Hey...you are the first to quote me on this site.
Congrats , new to this forum !!