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+--- Thread: Rakes? (/thread-703.html)
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Rakes? - ETC57 - 07-31-2012
Ok so with all the talk of rakes currently in general metalworking, I have to ask
just what is it?
I mean I have a rake in the garden shed and my pickup has a bit of a rake from the over load springs but what is a machine tool rake?
And yes I really don't know.
Jerry.
RE: Rakes? - EdK - 07-31-2012
Here you go Jerry.
http://littlemachineshop.com/Reference/RakeRelief.php
http://www.steves-workshop.co.uk/tips/toolgrinding/toolgrinding.htm
Just Google "lathe tool rake" and you'll get all kinds of information to soak up.
Enjoy!
Ed
RE: Rakes? - Highpower - 07-31-2012
(07-31-2012, 09:53 AM)ETC57 Wrote: Ok so with all the talk of rakes currently in general metalworking, I have to ask
just what is it?
I mean I have a rake in the garden shed and my pickup has a bit of a rake from the over load springs but what is a machine tool rake?
And yes I really don't know.
Jerry.
Jerry, that is a perfect analogy. Think of the caster angle on your truck suspension as "rake".
Positive caster = positive rake.
Neutral caster (0°) = neutral rake.
Negative caster = negative rake.
The road is your work piece, and the steering knuckle is your lathe bit.
Any help?
Willie
RE: Rakes? - ETC57 - 07-31-2012
Ok Willie,
so your talking about the angle of the cutting edge of the tool from top to bottom right?
Example: a raw blank 1/2" hss tool is 90 deg vertical to the top and bottom if you change that to 20 deg ether pos or neg that is rake
yes?
Thanks Ed for the sites!
Jerry.
RE: Rakes? - Tony Wells - 07-31-2012
No, that is the side clearance. The rake is the angle on the top of the tool, starting at the cutting edge itself, and either pointing or inclined up, above the axis of the spindle (negative) or pointing or inclined downward, below the axis (positive).
RE: Rakes? - ETC57 - 07-31-2012
OOOOOOk thanks Tony!
Jerry.
RE: Rakes? - DaveH - 07-31-2012
(07-31-2012, 06:28 PM)Tony Wells Wrote: No, that is the side clearance. The rake is the angle on the top of the tool, starting at the cutting edge itself, and either pointing or inclined up, above the axis of the spindle (negative) or pointing or inclined downward, below the axis (positive).Tony,
I think the parts above and below the spindle axis is going to confuse some of us. Thinking that is where the cutting edge of the tool should be
DaveH
RE: Rakes? - Tony Wells - 07-31-2012
Dave, since the most commonly accepted position of the cutting edge itself is on centerline, the top surface of the cutting tool can be neutral, if parallel with the flat ways on the bed, or inclined up or down out of parallel with them. I was simply trying to give a sense of direction of the incline on the top surface. Sorry if that was confusing. If I could sketch up something in paint, I'd post a rough drawing to try and show it, but I thought I'd try to just describe it.
I've heard some people call it "top relief", a term probably not too inaccurate.
RE: Rakes? - TomG - 07-31-2012
Jerry,
I like to think of rake as something that controls the chip. It is the angle of the top of the tool relative to horizontal. Positive rake makes the cutting edge sharper and is used on soft materials like aluminum or brass (or wood). Neutral or negative rake is normally used with carbide on high horsepower machines. Side rake makes the chip flow left or right. Back rake combined with side rake can control how the chip curls or breaks.
Relief on the other hand simply provide clearance so the flank of the tool doesn't rub on the part.
Tom
RE: Rakes? - Mayhem - 08-01-2012
Hi Jerry - here is a link to the first video in a multi-part series on sharpening turning tools. It shows the various relief and rake angles.
http://youtu.be/hrDr4rYLiAk