HSS Lathe Tool Shapes and Angles

[hammez]

Hello I am a new machinist could anyone help with angels and shapes that I should grind HSS tools to. I have a couple of tables that inform me of possible angles. would be glad of confirmation on these and any help on the shapes of basic required tooling

MT
Hammez

 

[ShopShoe]

If by "new machinist," you mean you have very little experience turning metal and grinding tools, I would sugfgest getting a few pre-ground tools and attempting to grind others to match.

I see that you are in the UK, so I don't know if there is a similar option, but LittleMachineShop here in the USA sells a set of ground tools and some blanks for just such practice:

Tool Bit Sharpening Training Set 4516

Turning Tools 4516 Six presharpened 1/4" high speed steel tool bits; Five unsharpened 1/4" tool bits; Sharpening instructions; Learn how to grind tool...

www.littlemachineshop.com

Otherwise, you can follow some of the instructions posted online or videos on YouTube. You will find what works for YOU with some practice, which may actually differ from some of the things on your chart a little bit.

If you search for "grinding toolbits" on YouTube, you will find lots of instructions by lots of different posters, with some periferal information as well.

Of course, I am assuming that you have a good grinder, a grinding wheel dresser, and a bench stone.

Sorry if I'm assuming too much in posting this. No ill will intended.

--ShopShoe

 

[trlvn]

When I was starting out, I found the following page a really good and concise summary of how to grind a usable HSS tool:

Basic Lathe Tool Grinding

Note that there is a 1-page pdf that you can print out and keep handy for reference.

There are tonnes of tool shapes but the one illustrated is a very good general-purpose variety:

Start with the angles suggested for steel--it will probably work fine for most brass and aluminum, as well. After you get some experience, then experiment with other tool shapes and grind angles.

YMMV

Craig

 

[SmithDoor]

Hello I am a new machinist could anyone help with angels and shapes that I should grind HSS tools to. I have a couple of tables that inform me of possible angles. would be glad of confirmation on these and any help on the shapes of basic required tooling
View attachment 142269
MT
Hammez

The most important is rake angle.
About the only steel that is different is A36 The rake is 7 ½° to 36° , soft gummy close to 36° and hard A36 is close to 7½°. Brass and bronze can be flat rake if tries to pull into the cut.
The rest more to anyone appointees.

Dave

 

[Charles Lamont]

Unfortunately, almost every reference you look at will give different figures. Home shop requirements are rather different from industry. In that table it looks to me as though top and side rake are the wrong way round. Also the side relief looks agressive. For our light cuts a smaller angle may be better. One ref in front of me says 5-9°, another 8-10°

For the best finish on the work you should have a good finish on the tool. I use a fine slip stone after grinding, and almost always put at least some radius at the tip.

 

[hammez]

ok thanks for the help.
it looks like I will start with just a left and right rough and finishing cutter.
any other help with setting up and things like that would be much appreciated as there is not a lot about my lathe around that I can find.

MT
Hammez

 

[trlvn]

ok thanks for the help.
it looks like I will start with just a left and right rough and finishing cutter.
any other help with setting up and things like that would be much appreciated as there is not a lot about my lathe around that I can find.

I would not bother grinding left hand tools until you need them. Cutting from left to right--away from the headstock--is just not common. Or do you have something specific that will require such a tool?

Craig

 

[Bentwings]

. When I started as apprentice I received a small honing kit it had a about a 3-4” triangle fine grit honing stone , a white super hard Arkansas with a very fine grit and a double sided dual grit diamond hone . Ironically I still have remnants of these the tri angle got dropped a number of time so is only about 2” today the diamond grit is still in the small shop lathe tool box All edges got finishing hone even carbide. Most tools had at least a small radius nose instead of sharp point. I still have some of the fine thread cutting tools the hones were probably the best kept secret to good finishes and even a thin cut off tool most tools were HSS
ok thanks for the help.
it looks like I will start with just a left and right rough and finishing cutter.
any other help with setting up and things like that would be much appreciated as there is not a lot about my lathe around that I can find.

MT
Hammez

 

[awake]

Here's the book that started many a home machinist: https://gadgetbuilder.com/How-to-run-a-lathe.pdf

 

[hammez]

I would not bother grinding left hand tools until you need them. Cutting from left to right--away from the headstock--is just not common. Or do you have something specific that will require such a tool?

Craig

Yep I have something that I need to make a shallow chamfer from left to right an it needs a square end so I will have to make a slightly modified LH tool. Although I could possibly make a special chamfer tool.

Hammez

 

[hammez]

Also does anyone know of a good place preferably in the uk that I can get A1 or A2 type chucks for a Churchill Cub.

Hammez

 

[sniffipn]

Here's the book that started many a home machinist: https://gadgetbuilder.com/How-to-run-a-lathe.pdf

p28. tool tip 5° above center - whats the reason please

 

[hammez]

p28. tool tip 5° above center - whats the reason please

I just spoke to a machinist and he said that that doesn't sound right.
Dunno if that helps.

Hammez

 

[terryd]

Hello I am a new machinist could anyone help with angels and shapes that I should grind HSS tools to. I have a couple of tables that inform me of possible angles. would be glad of confirmation on these and any help on the shapes of basic required tooling
View attachment 142269
MT
Hammez

Hi,

There is a lot of advice around the internet and YouTube, but I would get a copy of @The Amateurs Lathe' by L H Sparey. It is freely available via the normal online booksellers. Here is the advice from the South Bend Lathe Works 1934 handbook about setting the tool, the extra above centre height is to allow for normal flexing of the tool when cutting

And some advice on grinding from the same source:

TerryD

 

[terryd]

Hello I am a new machinist could anyone help with angels and shapes that I should grind HSS tools to. I have a couple of tables that inform me of possible angles. would be glad of confirmation on these and any help on the shapes of basic required tooling
View attachment 142269
MT
Hammez

Hi Again,

You could start looking on YouTube at 'This Old Tony ' video:


TerryD

 

[ajoeiam]

Hi,

There is a lot of advice around the internet and YouTube, but I would get a copy of @The Amateurs Lathe' by L H Sparey. It is freely available via the normal online booksellers. Here is the advice from the South Bend Lathe Works 1934 handbook about setting the tool, the extra above centre height is to allow for normal flexing of the tool when cutting

snip
And some advice on grinding from the same source:

snip

Useful advice if you are dealing with flexy toolholders (like the one pictured!!!).
If you are using a decent block style (4 sided) or something a bit more elaborate (like the multifix system) you really shouldn't have any flex in the toolpost.

You will find if you are follow this 'above by 5 degrees' recommendation that your finer cuts on smaller radii will not give you 'nice' results.
Why - - - that 5 degrees is enough to give you rubbing between the work and the relief angle on the tool.
Much is made of this angle - - - - its easy to see its need and usefulness if your using this 'hasn't been used much in quite some time' form of toolholding AND your using HSS cutting tools - - - then its easy to grind a slightly larger relief and away you go.

(Now if your using even brazed on carbide cutting tools - - - well you shouldn't need to much of any flex and then that 5 degrees above recommendation - - - well its for when you're running an ancient machine (think 1930 to 1940s) with HSS or high carbon steel tooling.)

Some of the recommendations in the very old standards are not accurate when using more contemporary equipment and tooling - - - imo.

HTH

 

[stanstocker]

Greetings,

Real short reply:

5 degree clearance front and side. Top rake depends on material. Zero degrees for brass, five to seven degrees for most steels, if you do enough to make it worth your time, 15 degrees for most aluminums.

Grinding direction should be perpendicular to the cutting edge to avoid weakening the edge.

This is based on using a block or quick change style holder where the tool body is parallel to the cross slide.

Use a fine stone or lap after grinding to put as close to a mirror finish on the faces at the cutting edge, particularly the top rake. A small amount of radius at the cutting corner is beneficial. The bigger the radius the smooth the cutting up to a point, the sharper the corner the rougher the finish but the tighter the inner shoulder detail can be.

Have fun, fool around with it, make some steel and aluminum wool. It will all become pretty clear with just a few cuts.

Cheers,
Stan

 

[terryd]

Useful advice if you are dealing with flexy toolholders (like the one pictured!!!).
If you are using a decent block style (4 sided) or something a bit more elaborate (like the multifix system) you really shouldn't have any flex in the toolpost.

You will find if you are follow this 'above by 5 degrees' recommendation that your finer cuts on smaller radii will not give you 'nice' results.
Why - - - that 5 degrees is enough to give you rubbing between the work and the relief angle on the tool.
Much is made of this angle - - - - its easy to see its need and usefulness if your using this 'hasn't been used much in quite some time' form of toolholding AND your using HSS cutting tools - - - then its easy to grind a slightly larger relief and away you go.

(Now if your using even brazed on carbide cutting tools - - - well you shouldn't need to much of any flex and then that 5 degrees above recommendation - - - well its for when you're running an ancient machine (think 1930 to 1940s) with HSS or high carbon steel tooling.)

Some of the recommendations in the very old standards are not accurate when using more contemporary equipment and tooling - - - imo.

HTH

Hi HTH,

Sorry to disagree but here is ALWAYs flex and play in any system even in what appears to be the most rigid. That is one of the reasons why parting is so difficult with a front mounted tool when there is no allowance for flex and the tool submarines at small diameters, at least that is the experience of mine over nearly 60 years of turning having broken 2 blades in that time. If any machine was absolutely rigid the slides would not move, even recirculating balls have some tolerances. The toolholders referred to in the SB books are actually quite rigid if mounted correctly, I learned to use those in the 1960s when serving my apprenticeship but have obviously moved on,

Regards

TerryD

 

[awake]

p28. tool tip 5° above center - whats the reason please

Several good replies above. I would add that anything you read in any book should be considered a place to start, from which you make adjustments to suit your context - machine, material, cutting tool, etc. I will say that I normally position my cutting tools on center, not above - this is on a well-worn Cincinnati TrayTop 12.5 x 30 lathe - a much heavier and more rigid lathe than the typical 9" Southbend, though the amount of wear can be a factor for both. The exception is my parting blade - I use a parting blade with a u-shaped top (which curls up the chip to allow better clearance). The trick with this type of blade is that the bottom of the U needs to be more or less on center, which means the top of the legs of the U will be above center.

 

[Richard Hed]

Hi HTH,

Sorry to disagree but here is ALWAYs flex and play in any system even in what appears to be the most rigid. That is one of the reasons why parting is so difficult with a front mounted tool when there is no allowance for flex and the tool submarines at small diameters, at least that is the experience of mine over nearly 60 years of turning having broken 2 blades in that time. If any machine was absolutely rigid the slides would not move, even recirculating balls have some tolerances. The toolholders referred to in the SB books are actually quite rigid if mounted correctly, I learned to use those in the 1960s when serving my apprenticeship but have obviously moved on,

Regards

TerryD

I broke two blades also when I was younger. I didn't know to slow down the speeds and ithe blades were only half inch wide and very thin.