Internal Key-way Shaping

[IanTParticipant @iant]

Posted by Hopper on 27/11/2020 04:48:28:

Posted by Nigel Graham 2 on 24/11/2020 00:15:33:

* The shaper. I do know too that the cutting edge should be under the clapper fulcrum, but learnt that only quite recently, and I have seen and probably been guilty of some very unfair tool-setting on shapers.

Carry on the way you have been doing it and you will be just fine. I can't think of any good reason why the tool should be directly below the fulcrum — unless there is something special about the model-sized machines?

The reason this is often mentioned Hopper is in relation to "cranked" tools (a swan-neck for instance). On a lathe, a dig-in will tend to pull the cutting edge away from the surface being cut (this surface being round). On a shaper, a dig-in where the cutting edge is in front of the fulcrum will dig-in further (the surface being flat). If the cutting edge is inline or behind the fulcrum, it will be pulled 'out' of the cut. I think Nigel has been looking at Bradleys shaper book or similar – it's mentioned there.

I have some forged swan-neck tools and there are two types. Those with the cutting edge inline with the top of the tool shank are for lathe use and those with the cutting edge inline with the bottom of the shank are for shaper use. Obvious when you know the reason.

In practice (using normal tooling) – it's something to be aware of – but not to worry about too much. Just don't over extend the tool (or vertical slide) to avoid any unnecessary deflection and don't take too deep cuts. Also don't "pack" the tool bit to the fore, always get the cutting edge back as far (near to the clapper) as possible.

Basically try to avoid dig-ins.

Regards,

IanT

Edited By IanT on 27/11/2020 10:21:41

[HopperParticipant @hopper]

Crikey. Swan neck tools haven't been used since Noah was a midshipman. But I guess many shapers are of that vintage!

Possibly more of a concern on the small hand driven jobs than the big industrial Cincinnatis, I would guess.

But I still cant see how having the tool point in line with the clapper pivot would make a jot of difference to a dig-in because the clapper does not pivot in that direction at all. It is for all intents and purposes fixed on the forward stroke, held firmly against the end of the ram by the pressure of the cut. Surely, its the swan neck tool that does the moving and allows the tip to spring that tiny bit away from the job?

Interesting.

[HopperParticipant @hopper]

PS all you ever wanted to know about shapers, and then some more, is probably to be found among this amazing collection of PDFs of old shaper manuals and all sorts of other good stuff. (All out of print and copyright by now.)

http://www.neme-s.org/Shaper%20Books/

Edited By Hopper on 27/11/2020 11:07:12

[Nigel Graham 2Participant @nigelgraham2]

I've been searching for the text-book I have / had that goes into quite a bit of detail on using the shaper.

Things vanish in my house and workshop, but I've a sneaking suspicion I lent the book to a friend… before the Covid World Tour.

I'd wanted to quote from it. Among other things I a m pretty sure it shows the geometry of the tool action, explaining the effect of tool distance from the fulcrum. However I did look in one or two of my old industrial (rather than model-engineering) books, as these show sample machines most of us could not accommodate. In these the shapers do appear intended used rather as in Hopper's photo – no mention of hats though – but that could be misleading.

A dodge I have found helpful is to file a chamfer along the leading edge of the work, so the tool is slightly eased into the metal rather than having to chop into a vertical face.

What I also recall from the AWOL book, which I think is a model-engineering text rather than an apprentice-training reference, is a simple shaper tool-holder based on an old bicycle crank. It is trimmed (by shaping?) to fit the clapper box, and a cylindrical holder for round-section tool-bits fits in the crankshaft hole. It was designed for down-cutting both sides of the work as well as the top, with just a simple adjustment.

* * *

My original enquiry was prompted by having to build a drive for a small horizontal mill (motor speed nearly 1400rpm, spindle around 60rpm), and thinking of the 2-speed transmission for my steam-wagon – for which there are no drawings.) I've taken a break from the mill project as I'd hit a sort of impasse, to complete a Hemingway kit 'Worden' T&C grinder I started ages ago. That has full drawings, a luxury despite the frustrating way some parts are dimensioned!

[HopperParticipant @hopper]

The link above has manuals for Boxford and other small shapers that might be useful. No hand power that I saw.

[not done it yetParticipant @notdoneityet]

A dodge I have found helpful is to file a chamfer along the leading edge of the work, so the tool is slightly eased into the metal rather than having to chop into a vertical face.

Not a dodge at all. A veritable necessity when cutting hard materials with a hand shaper, particularly if taking a roughing (heavy?) cut.

[Ex contributorParticipant @mgnbuk]

A dodge I have found helpful is to file a chamfer along the leading edge of the work,

A filed or angle grinder ground chamfer was also put on the exit edge of cast iron components when shaping or planing to help prevent the corner from shelling off.

The machinists at work mill a chamfer all round the edge of graphite blocks before facing a surface for the same reason.

Nigel B.

[John HaineParticipant @johnhaine32865]

I've only had to do one keyway for which I used the lathe (S7) and fed with the rack. It was tedious but worked, in a pulley that I had to sleeve to fit a motor shaft when I added a VFD to my mill.

I have wondered whether the leadscrew would be stronger than the rack – though tedious by hand, since my lathe has CNC one could write a bit of G code that simply drives the Z axis back and forth over the required distance and slowing adds X feed to put the cut on. The same thing might be done on a CNC mill. My lathe has the standard Acme leadscrew on Z.

[Ady1Participant @ady1]

Anything that removes material will make life easier for the final cutting

Hacksawing, filing, drilling

[HopperParticipant @hopper]

Posted by John Haine on 01/12/2020 09:52:58:

I've only had to do one keyway for which I used the lathe (S7) and fed with the rack. It was tedious but worked, in a pulley that I had to sleeve to fit a motor shaft when I added a VFD to my mill.

I have wondered whether the leadscrew would be stronger than the rack – though tedious by hand, since my lathe has CNC one could write a bit of G code that simply drives the Z axis back and forth over the required distance and slowing adds X feed to put the cut on. The same thing might be done on a CNC mill. My lathe has the standard Acme leadscrew on Z.

Could be a bit wearing on the old halfnuts I reckon.

LH Sparey or Ian Bradley suggests an easy way of converting the existing topslide into a slotting cutter by removing the topslide feed screw and using a long lever to crank the topslide back and forth.

The lever is pivoted on a bolt sticking up from a piece of 2" round bar stood on end and bolted to one of the cross slide T slots behind the topslide. And is attached to the topslide via a nut and bracket etc on the toolpost clamping stud. Lever then sticks out about another 18" or so. Easier to crank and no stress on feedscrews or racks etc.

I swore after the last time I tediously slotted a faux-Myford change gear using the rack method I will never do it again and will make one of the above.

A bit of fettling and a variable stop could be made to use it for engraving lines on handwheels and the like.

Edited By Hopper on 01/12/2020 10:45:14

[Roderick JenkinsParticipant @roderickjenkins93242]

Like this:

 

I think it's  a Len Mason design.  Came with my s/h lathe.

Rod

Edited By Roderick Jenkins on 01/12/2020 11:19:33

[IanTParticipant @iant]

Posted by Hopper on 27/11/2020 10:54:18:

Surely, its the swan neck tool that does the moving and allows the tip to spring that tiny bit away from the job?

Yes, exactly Hopper – it's the tool and/or holder flexing that was being addressed. Some shaper set-ups require quite a lot of tool extension – usually for 'reach' reasons, where the tool has to be over-extended to get to the bottom of a cut (without the ram or slide fouling).

The older Shaper references usually are giving examples of 'forged' (carbon steel) tools, where the tool shank was shaped to present the cutting edge in various ways. Swan-necks were only one variation of this, designed to minimise chatter. I've got some examples buried away somewhere, I'll dig them out if I remember later.

Nigel, your bicycle crank holder is a version of a what I would call a 'universal' tool holder (as made by Armstrong in the US for instance) which allows the tool bit to be held at a number of angles on either side of the holder. Another advantage of this type is that the tool can be held to the rear of the shank, which is preferred as it also helps with the dig-in issue – although I have seen them mounted to the fore which seems less desirable but may be necessary for other reasons.

Regards,

IanT

[HopperParticipant @hopper]

Posted by Roderick Jenkins on 01/12/2020 11:13:32:

Like this:

I think it's a Len Mason design. Came with my s/h lathe.

Rod

Edited By Roderick Jenkins on 01/12/2020 11:19:33

That's the way to do it. Even simpler than attaching to the toolpost. I have a new project for the week. Thanks for the pic.

[Nigel Graham 2Participant @nigelgraham2]

Simpler than attaching to the tool-post, and possibly stronger.

Might be worth making a special tool-holder that goes on the stud vacated by the QCTP block, to bring the tool much closer to the line of action, and with a down-projecting flange that transfers much of the force from the stud to the front face of the slide itself.

My thinking there is that although taking very light cuts, using the lathe like this may still put more force on the top-slide than does normal turning. The flange would also automatically align the tool every time with the slide, if the clamp part is bored in-situ.

[not done it yetParticipant @notdoneityet]

Lathes are for turning; shapers are for shaping. No contest, really? You have a good manual machine so best to get organised to use it for shaping, are my thoughts on the subject. Why try to make a shaper out of a (small?) lathe when you have the proper machine for the job already?

[Roderick JenkinsParticipant @roderickjenkins93242]

Posted by not done it yet on 02/12/2020 06:25:22:

…Why try to make a shaper out of a (small?) lathe when you have the proper machine for the job already?

In my case it's because the job is already set up and securely held in the lathe and cutting the keyway is just one of a number of operations on the part. Much the same reason that I sometimes choose to use my tool post milling spindle rather than the milling machine. So many ways to skin a cat 🐱

Cheers,

Rod

[Roderick JenkinsParticipant @roderickjenkins93242]

Hopper,

I've found the original source for the slotter in Len Mason's "Using the small lathe"

Although originally published in 1963 I still find this book a useful source of information on workshop techniques.

Hope this helps,

Rod

[HopperParticipant @hopper]

Thanks. I'll buy a copy. I have all the other grand masters of yore. Always a treasure trove.

[Howard LewisParticipant @howardlewis46836]

Hopper,

Once, I cut a small square hole for a scooter speedo drive, by holding a 1/8 toolbit in the tailstock, and racking the barrel to and fro (Having drilled a 1/8 hole and with 90 rotation of the chuck between cuts ) using the traverse screw, with the Tailstock locked to the bed.

If you don't want to mess about with your Top Slide, I can recommend making the Peter Robinson Slotting Tool, using the casting from College Engineering. I added a grease nipple to the top of the casting, to lubricate and improve the "feel".

It was designed for the Myford 7 Series, but after selling the ML7 , I made a riser block to use it on my BL12 – 24.

You may nee to do something similar, if you want to use on your Drummond.

Howard

[John PParticipant @johnp77052]

The photo here shows this keyway slotting tool
that was published in the Model engineer in the early
nineties issue 3980 page 541 ,is available in the My
Hobby store plans list as "Slotting attachment for the
Myford super 7 lathe " plan no WE 68.
Although similar to the Mason design is simpler to make
and eliminates the shortcomings in his design ,the lever
thrust position is directly behind the toolbit so there is no
couple effect pushing the tool upwards in use .
The topslide is only a guide for the tool, the tool block
automatically indexes the cutting tool on centre
height and the tooling is provided with reference for
grinding the tool cutting edge.

John

[John HaineParticipant @johnhaine32865]

Posted by Hopper on 01/12/2020 10:43:50:

Posted by John Haine on 01/12/2020 09:52:58:

I've only had to do one keyway for which I used the lathe (S7) and fed with the rack. It was tedious but worked, in a pulley that I had to sleeve to fit a motor shaft when I added a VFD to my mill.

I have wondered whether the leadscrew would be stronger than the rack – though tedious by hand, since my lathe has CNC one could write a bit of G code that simply drives the Z axis back and forth over the required distance and slowing adds X feed to put the cut on. The same thing might be done on a CNC mill. My lathe has the standard Acme leadscrew on Z.

Could be a bit wearing on the old halfnuts I reckon.

………..

Well, I wonder. One of the nice things about CNC is that the machine does all the boring work and you can do things that would be much too tedious manually. In this case you could use a very small feed per cut (obviously big enough that the tool actually cuts and doesn't rub) which would make the job impossibly tedious by hand.

[HopperParticipant @hopper]

Posted by John Haine on 02/12/2020 09:42:15:

Posted by Hopper on 01/12/2020 10:43:50:

Posted by John Haine on 01/12/2020 09:52:58:

I've only had to do one keyway for which I used the lathe (S7) and fed with the rack. It was tedious but worked, in a pulley that I had to sleeve to fit a motor shaft when I added a VFD to my mill.

I have wondered whether the leadscrew would be stronger than the rack – though tedious by hand, since my lathe has CNC one could write a bit of G code that simply drives the Z axis back and forth over the required distance and slowing adds X feed to put the cut on. The same thing might be done on a CNC mill. My lathe has the standard Acme leadscrew on Z.

Could be a bit wearing on the old halfnuts I reckon.

………..

Well, I wonder. One of the nice things about CNC is that the machine does all the boring work and you can do things that would be much too tedious manually. In this case you could use a very small feed per cut (obviously big enough that the tool actually cuts and doesn't rub) which would make the job impossibly tedious by hand.

Only one way to find out!

One the line of getting away from tedious repetition by hand, I wonder if a modern update of one of the above mentioned slotting tools or topslide conversion could be converted to a powered version using a small drive motor and gearbox cheaply available these days on Aliexpress etc. They seem to have no end of automation components available, There must be something off the shelf that could do the job of powering a slotting tool or topslide conversion?

[John HaineParticipant @johnhaine32865]

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

[HopperParticipant @hopper]

Posted by John Haine on 02/12/2020 10:51:49:

**LINK**

Edited By JasonB on 02/12/2020 11:03:23

???? Did somebody swear?

[HopperParticipant @hopper]

Heres what I'm talking about:

Not sure what kind of old motor/gearbox unit he's driving it with. Could be a car starter motor? But looks like a capacitor on the side of it? His wiring is not exactly exemplary and should not be tried at home.

Anyhow, the modern version of the traditional lathe slotting tools could be made thus with the use of a stupid cheap automation motor and reduction gearbox from China, of which there are a million on sites such as Aliexpress etc. And I suppose that dreaded auction site. Just need to find the right one among the millions listed.

It would make quick work of cutting keyways in steel or cast iron gears and pulleys and could work for gear cutting too, with suitable indexing device on the lathe spindle.

Edited By Hopper on 04/12/2020 07:27:20

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