Lathe tool types

Finally got a set of 8 HSS tools for my first lathe (Hobbymat MD65).

Trying to figure out all the types by comparing to pictures from books and internet, but still having some trouble. Can someone please explain the name and purpose of each one?

I'm also wondering if they are supposed to be ready to use as-is, or is it common for final grinding/honing to be done by the user (like many woodworking tools)? The reason I'm asking is that the tools all have sharp noses with no rounding visible to my naked eye.

I'm somewhat confident I guessed 5 out of 8 correctly, from left to right:

1 - Right (roughing?) turning tool - why is it offset?

2 - Left turning tool like #1

3 - External threading tool

4 - ?

5 - Grooving / part-off tool

6 - Boring tool

7 - ?

8 - ?

Here's the link to the set I bought.

I'd like to learn to grind my own tools, have bought and restored a 200 mm bench grinder, one wheel is 36 grit aluminum oxide, and the other is 60 grit white aluminum oxide. I also bought a couple of HSS blanks and a length of square mild steel to practice on. I read Harold Hall's book on lathework and it talks about grinding tools, however I had a little bit hard time converting the drawings to 3D in my head, so figured I'd buy a set of ready-made tools to have some real example in front of me.

Edited By Gene Pavlovsky on 04/05/2020 16:01:59

Does the supplier not know? always pays to use one who can tell you what the sets contain

Edited By JasonB on 04/05/2020 16:05:06

Jason, I was actually trying to find a product description like the one you posted - thanks for that, but the ones I found listed the tool names in obviously different order than their pictures, making it more tricky.

The company I bought from, RC Machines here in Luxembourg, didn't have the description for this set. Some of their product descriptions are quite lacking, compared to the well-known UK suppliers. I can of course contact them and ask for information, but would be nice to get more in-depth information from the experienced folks around here And I'd like to know more details than a product description gives, like is there any extra grinding to do after buying a ready-made set, like rounding some noses for example, honing with honing stones or sandpaper?

Edited By Gene Pavlovsky on 04/05/2020 16:15:10

Posted by Gene Pavlovsky on 04/05/2020 16:14:56:but would be nice to get more in-depth information from the experienced folks around here And I'd like to know more details than a product description gives, like is there any extra grinding to do after buying a ready-made set, like rounding some noses for example, honing with honing stones or sandpaper?

Edited By Gene Pavlovsky on 04/05/2020 16:15:10

These HSS types like the ones in your picture can be used straight out of the box. The cheap brazed carbide type like these require some honing before use.

Ketan at ARC.

Based on the ones I linked to then they should not need grinding straight out of the box but may be honed on a fine diamond slip or fine abrasive placed on a flat surface, Try to avoid rocking teh tool or slip as that will gibe the end a slight convex curve that can start to rub.

Due to their "chip breaker" design - the concave edge I would not round the corners as that can make it harder to set the tool on ctr height.

Again due to that same feature you really only want to hone or if needed after a lot of use just the end and not the side on the two knife tools for example.

Edited By JasonB on 04/05/2020 16:23:34

So the grooves are chip breakers, already learned something. And yeah I can see how rounding the nose or grinding/stoning the side could mess things up because the center height would change.

I compared my tools with the ARC tools picture, and I think that #7 in my set is actually the 60 degree threading tool. I have a simple angle gauge for woodworking tools and #7 fits the 60 degree slot. The tool #3 is not for threading, then, it's much more pointy, somewhere between 35 and 45 degrees. So what is it, a facing tool perhaps?

#8 looks like the chamfer tool in the ARC set, #4 is the same general shape with same angles but different lengths of front faces, and widths of the grooves, are they both for chamfering? Why two of them?

1 & 2 : Turning tools are offset so that you can work close to the chuck or revolving tailstock centre with less risk of collision with any part of the toolpost or packing you might have underneath.

4 is more of a roughing tool with a chipbreaker ground in the top face. The idea is supposed to be that the angled face takes out any crossslide leadscrew backlash and reduces chip thickness. I've always found any such effect marginal at best.

7 & 8 seem to be variants of the same thing. 7, with no top rake or chipbreaker, might be supposed to be for brass.

Generally, I 've never really got on with such sets and have ended up grinding them to whatever shape I wanted. A simple knife tool, with a cutting edge square to the spindle axis, a few degrees - doesn't matter exactly how much - top side rake, front and side clearance, maybe 15 - 20 degrees plan trail angle, will do 90-odd % external turning work.

Here's a bunch of mine - plain knife tool on left. Most of them have some other funny shape on t'other end:

4th from right with cranked grooving tip is for thread clearance undercuts close to the chuck.

It looks like 4 and 8 are the same. If they are chamfer tools I assume it is so that you can have one mounted to do inside chamfers and facing and one to do outside chamfers.

I would say you are missing a left hand roughing tool that has angles like No 4 but no chipbreaker, just top relief. Notice how the angle of the end is wider than No 1 so it is stronger to do the roughing and save your nicer tool for the final cut including 90 degree shoulders.

Are there any cons to have various forms cut on the other side of the bit? Perhaps more awkward handling?

It's starting to get more clear on the whole. I am still not sure what's #3 for, with it's rather sharp angle it wouldn't be very strong, so for some delicate finishing jobs, but what exactly, facing close to the center?

Bazyle, the roughing tool you describe seems like a good first exercise for grinding my own. Is #4 not good for roughing because of it having a chip breaker? Also missing from this set is an internal threading tool. And I wonder why this external threading tool has 0 top rake.

Edited By Gene Pavlovsky on 04/05/2020 17:37:07

So that no one gets confused, are we all clear on what we mean by Right and Left when talking about lathe tools?

A Right Hand tool actually faces, and cuts, towards the chuck when mounted in the toolpost.

A Left Hand has its cutting edge towards the TaIlstock when mounted in the toolpost, ready to cut.

This confused me for a while when I first started machining.

#1 is a Right Hand knife tool, while # 2 is a Left Hand Knife tool.

The 45 degree tools ( 4 and 8 ) could be used for producing a chamfer on the OD of a workpiece, either to help a Die start cutting, to help the workpiece enter a close clearance bore, or to take off a sharp edge, that might result from facing or knurling a workpiece.

# 6 looks to be an external threading tool, with, as you say, no top rake.

#6 could be used to part off small diameter work, or to make a groove for an O ring of suitable size, or an undercut at the end of en external thread.

Whatever tool you use, it is important that the cutting edge is on the centreline. Too low and it will not cut properly. Too high and the tool will rub rather than cut.

If the tool is on the centreline of the work, a facing cut will leave no pip in the middle of the job, and the tool will cut properly..

A useful exercise would be to make a centre height gauge, to aid setting tools to the correct height. There are various ways of doing this, ranging from "trial and error" to measurements to accommodate the slight (we hope slight ) eccentricity always found in a 3 Jaw chuck.

The tool can be brought to the correct height by putting shims under it, so that when clamped firmly in place, it is at centre height. Shims can be made from pieces of tin (Most tins are about 0.010" (0.25 mm ) thick. Soft drinks cans are aluminium which is softer, and can be hammered to make them thinner, but may eventually become even thinner from the clamping loads applied to the tool.

In the interests of rigidity, to reduce the chances of chatter, try to use the minimum of tool overhang.

If it chatters, reducing the speed may help. A tool with a wide cutting face is more prone to chatter when taking a deep cut. Reducing the depth of cut may improve matters.

Hope that this helps, and is not teaching granny to suck eggs.

Howard

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That’s a point well-worth making, Howard

... and it’s logical enough when you remember that with the job between centres; the Right Hand tool works on the Right Hand end of the job. < etc. >

MichaelG.

But so can a left hand tool when held along the lathes axis for facing

Easier to say a RH tool moves from the right and a LH tool moves from the left when the line of movement is viewed across the front of you.

Edited By JasonB on 04/05/2020 19:22:38

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Your first statement is true enough ... Your second is nonsensical in the context of the first unless you insist on standing at the end of the lathe.

I intended mine as a simple aide memoire, not a contortionist’s act. ... variations on the theme being intuited by the operator.

But you’re the Moderator.

MichaelG.

Edited By Michael Gilligan on 04/05/2020 20:35:55

Grumpy

I was just trying to keep with left and right and not bring towards and away into the description, I'm sure some could have put it more eloquently but I'm not so good with words but just get it done.

Also your comment that the RH tool "works on the right hand end" of the work only applies as it starts the cut the rest of the time it is working it's way along the circumference.

My comments were probably biased by the types, of turning tools that I use, but did not want to complicate matters in a thread started by a relatively inexperienced operator

Hence omission of some of the slightly more unusual way of using tools. .

Since the question was about a selection of HSS tools, I deliberately did not mention Tangential or carbide tipped tools, or tool grinding.

In my view, those are matters for when more experience has been gained.

But Jason has provided further clarification of the nomenclature, which has to be good.

Howard.

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Yes, a little

MichaelG.

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Sorry, Jason ... I have to disagree : It continues to work on the newly formed “right hand end”

The original intent of my post has either been absorbed by those who might benefit from it, or it will be lost in the further debate.

MichaelG.

I'm sure my fellow Moderator will not mind me pinching this illustration from his" lathework for beginners" series that explains the use of these preground lathe tools.

As can be seen the RH tool works on the circumference of the work moving from the right as indicated by the arrow, the LH tool can also be used on the circumference and moves from the right, it can also be used on the end and when viewed end on is still moving from the left.

Due to the chip breaker on these particular tools I would not recommend the use of the RH tool to work on the right hand end of the work, This is however possible with tipped tools and HSS ground differently.

Edit, crossed posts, Anyone (except you) looking at that sketch of Neil's would call the right hand end the part the end that the LH tool is shown facing not the shoulder half way along.

Edited By JasonB on 04/05/2020 20:59:19