Thread: Poor finish with my finishing tool.

I get totally confused bythe terms back rake, side rake, upside down rake etc...

I prefer to use the terms... Cutting edge angle, front clearance angle, side clearance angle, angle on inclination..

Clearance angles are just that, for clearance... Cutting edge angle varies for the material.... MS is around 7-10 degrees.... Angle of inclination is the angle the tool angles back when you look along the cutting edge....The very common square HSS holders have this set at around 15 degrees..

Lather,
The tool looks good and it looks like you have a have a good eye and steady hand when grinding.

RC,
Just following on the names that are common to every one and have been for many years. If we stick to this, then when people go looking for more info on it, it's all the same terminology.

Dave

Dave just going by my tafe book I wonder if the terms side rake and top rake etc are US terms as the tafe book only mentions normal rake which the wedge cutting angle. Normal rake angles are

0 for brass
8-10 for cast iron
10-15 for mild steel
20-25 for copper and aluminium.

Clearanc eangles to be 3-8 degrees... more for aluminium..

Then you have the approach angle andnose radius.

Carbide inserts are different in that they have positive and negative inserts. From what i understand allnthis means is negative inserts have 0 clearance built into the insert and theholder holds them down at a angle. While positive inserts have the clearance angle built in... negative inserts can be double sided and have stronger edges but require more hp for a given cut and are not as good at getting a good surface finish.

dave, wish i had that steady a hand, used a platform on the grinder which can be tilted which saves a lot of hassle.
for the last edge or side rake, set the platform to the correct angle, then placed another platform on top and angled it until the cutting edge was horizontal to the grinder.

I would love to see a consensus on names for tool angles. Every source I see seems different. And every discussion I've seen just gets confusing and resorts to pictures.

I just checked and it sounds like we have the same book with the normal rake and those numbers, is it a 3 volume set? I was just referencing mine to the South Bend link I gave to save confusion and is what I call it as well.
Just looking in that book I see they call back rake inclination and the side rake normal rake.

Dave

Bryan, your right about that, found this on wiki, when trying to figure out the angles to grind when trying to replicate the angles Dave posted.

File:Tool Bit Geometry.JPG - Wikipedia, the free encyclopedia
makes sense to me.

Originally Posted by Bryan

I would love to see a consensus on names for tool angles. Every source I see seems different. And every discussion I've seen just gets confusing and resorts to pictures.

I think it is easier to think of it as back rake and side rake, as that describes exactly what it is in simple terms.

Dave

Give it time and practice you will be able to do it free hand, though jigs do get you spot on the first time. Doesn't really matter which way you do it as long as you get good results in the end.

Dave

Originally Posted by lather

dave, wish i had that steady a hand, used a platform on the grinder which can be tilted which saves a lot of hassle.
for the last edge or side rake, set the platform to the correct angle, then placed another platform on top and angled it until the cutting edge was horizontal to the grinder.

..."as that describes exactly what it is in simple terms."

only if you are used to those simple terms.
To me 'rake' implies at best the angle of the teeth on a garder implement. I'm used to the terms cutting angle or clearance angle. "back rake angle" is only barely meaningful to me. I would consider that more relevant to the angle of the tool holder than the tool edge though.....

A consistent set of tems would be very helpful.

Joe

There might be some confusion in that with cutting tools there is only negative rake and positive rake. Rake is an inclination not an angle. Everything else is cutting and clearance angles.

Phil

Originally Posted by jhovel

..."as that describes exactly what it is in simple terms."

only if you are used to those simple terms.
To me 'rake' implies at best the angle of the teeth on a garder implement. I'm used to the terms cutting angle or clearance angle. "back rake angle" is only barely meaningful to me. I would consider that more relevant to the angle of the tool holder than the tool edge though.....

A consistent set of tems would be very helpful.

Joe

Hi Joe,
If you follow that link I posted on page one it shows what I call standard terms, and I find most people on the forums also use these terms to describe a tool.

Dave