Lathe Four Jaw Chuck Laser Light Centring Aid

What on earth is this weird creation ? ……..

4 jaw chuck laser centring device

One of my favourite additions to the workshop has been a laser centring tool for use on my Tormach PCNC milling machine.   The tool consists of a low cost laser diode mounted on a 3D printed disc and with a 19mm steel shaft.   The tool is held in the Tormach spindle power drawbar.   The laser is angled inwards towards the spindle axis at approximately 20 degrees.   The 3D print has facilities for a battery supply and ON/OFF switch such that when the laser disc is pulled into the power tool bar collet it switches on the diode.

In use, as the spindle is raised or lowered, the rotating diode creates a circle of light on the milling table which can be used to locate and centre the spindle on features of the item being machined.   This might be to locate the centre of a hole or the centre of a block depending on need.

A full write up of the mill related item is available here.

I recently had the need to use my four jaw centring chuck on my Myford lathe.   Usually I duck and dive to avoid having to use the 4 jaw as I find it frustrating to set up.  This recent bout of frustration lead me to wonder if I could adapt my laser centring tool for use on the lathe such that it would give me a guide ring of light to show where the material was sitting relative to chuck centre.

On the milling version the laser rotates and the job stays fixed.   On a lathe version this would be similar.  The chuck would be stationary and the laser would rotate in the tailstock.

The full write up can be downloaded here. and the Fusion 360 file is here lathe_centring_device v4

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Handy Tormach TTS Collet Storage Idea

A Storage Tip

I am quite anal in needing to have a tidy workshop with everything having a place where I can find it easily.   It is a kind of insurance policy to perhaps give me a bit longer time in the workshop before I lose the plot altogether.  (The less palatable advantage is the dealer who comes in to clear my workshop when I am in turn in ‘a box’ can easily see what a treasure trove he has stumbled on.   We’ll move swiftly on from that thought).

To this end I have settled on using 5 Litre storage boxes for all my ‘stuff’ (technical term as defined by my long suffering wife).   These are readily available in the UK at Dunelm and on the net.   They are made from a very durable plastic and supplied with a lid which is rarely useful for my application.  I believe they are principally intended for ladies to store their shoes.   I suppose we could call them Marcos boxes ?

The boxes have a 6.5″x 12″ footprint and are 4″ deep.  It is surprising just how much workshop kit can be stored in these (and of course nicely labelled).   The 12″ is just not long enough for 13″ silver steel but a little hang over can be tolerated for such useful material.

marcos storage boxes
How sad is this ? Just a small section of my anal storage system

I have accumulated a reasonable (by my standard) set of Tormach TTS tooling collets with my preferred tools permanently fitted.   These are each numbered to match my tool table entries in PathPilot.  The numbering is done using an Edding 750 white paint marker.

My solution to storing the collets was to use Marcos boxes.   I used a sheet of Dural (150mm x 290mm) and punched a (3 x 6) matrix of 20mm holes into it to take the collets.   The Dural sheet sits on 5 off 10mm diameter x 36mm long spacers.

Tormach TTS tool storage
‘Marcos’ TTS tooling storage side view showing Dural plate

To give you some idea of the strength of the boxes,  you can pick up one of these fully loaded with tools by the front wall and your wrist will break before the box does. (Well you know what I mean).

You will notice in the above photo that after some expensive clumsy breakages I now fit 3D printed caps over the most fragile tools such as carbide PCB drills.

Tormach TTS storage
‘Marcos’ TTS storage box showing protective 3D printed caps over fragile tools

So a bit of a slow news day but thought this might stir an organisational initiative somewhere ……  

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Machining a job that is outside a milling machine’s table travel using Fusion 360

Introduction

This write up is not for the purists with years of experience but is an explanation of how I thought through how to machine something over size that would not fit into my Tormach PCNC440 milling footprint as a single operation.  Hopefully it might help others to grasp the process.

The challenge began when a local turret clock expert came to me and asked if I could machine a new Hour and Minute Hand for a clock he was working on.   The Hour Hand was around 14” long and the Minute Hand some 18” long.   

Here is the Fusion 360 view of the minute Hand.

clock minute hand milled in three steps

Clearly these lengths were way outside the 440 table X movement (10”) so a plan was needed.  There then followed a lot of staring into the distance at mealtimes and also at bedtime accompanied by vocal “hmmm”s as I tried to mentally visualise what was needed.  This idiosyncrasy is something my wife has come to terms with over the years…..

My conclusion from this mental preparation was that I needed to be able to accurately step the stock across the tooling table and then take two or three bites at the profile machining.  

What follows would almost certainly benefit from a video but sadly I am not set up for this. 

Click the link below to download the PDF document.

Milling an oversize object

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Stevenson Collet Block and the Angle of Dangle

Often a project comes along and it has you scratching your head how to go about it.   

The following job was simple and it could have been hand filed but my preference was to machine it.  The fact that I needed to make two added to my thinking.  (aka – I am fundamentally a lazy person …. and I follow my father’s adage that if a machine can do it a human shouldn’t)

You can simply regard the challenge as looking like a screwdriver blade but I needed to have it with the flats exactly on opposite sides, the end of the flats needed to come together to a defined blade point thickness (0.3mm) and the length of the flat taper had to be a defined length (30mm).   Here is a simple sketch.

taper milling

What I am about to describe is not magic and I am probably teaching many a granny to suck eggs (is this a universal saying or quintessentially English and how did it originate ?) but it might help someone somewhere save a few minutes of their life.

Stevenson Blocks in my opinion are the most elegant pieces of workshop tooling ever invented.   They consist of an accurately machined block of steel with an ER collet mounting.   Really quite simple.  They come in different ER sizes and the block can be square or hexagonal cross section.   These are they below and ArcEurotrade are one possible source.

stevenson collet blocks

If you have to machine a square head or hexagonal head on a piece of round stock they make the job so easy to run and make the result uniform, symmetrical and central.   Likewise centre drilling of round stock becomes so much more simple.  IMHO no workshop should be without Stevenson’s Blocks.

Back to the job in question.   I drew out the geometry and calculated I needed to set the 5mm round stock at an angle of 4.48 degrees.  Non scale sketch below.Angle calculation using Tangent Rule (Tangent rule – I can’t remember opposite and adjacent etc and remember it instead from – “Some People Have Curly Black Hair Through Persistent Brushing” where B = Base, H = Hypotenuse and P = Perpendicular).

I could have simply set the stock in the milling vice at the required angle but it would be a real pain getting it correct and protruding the right amount to skim flat. The resulting set up was as follows and you can see how the Stevenson Block came to the rescue.   

The 5mm stock was faced off and then marked at 30mm from the end and with a score line and then mounted in the Stevenson Block.

setup for milling round stock at an angle

My angle setter just fits nicely on the Block surface and has a magnetic base. This setup makes it so easy set the stock angle by  ‘hinging’ the Block up and down against the bottom edge of the Block and the angle plate surface.  (Clearly for other angles the height of the hinging point support would need to change).

Once set, the cutter is traversed in ‘X’ up and down the stock until the run out point coincides with the 30mm mark. Once the first side is cut, the stock and Block (could this be the name of a pub for engineers ?) are rotated 180 degrees which is fix defined by the Block lower surface edge.  The second side can now be run.

complete assembly set up for taper milling

I said it wasn’t magic but it beats filing and is far more accurate than I would have achieved by hand.   Good result.

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Automated Wheel Cutting GCode for the Tormach with the Sherline CNC Rotary Table

I have been putting this off as I thought it would be hassle and in fact it was very simple.

Here is the code which is the first time I have ever used a sub-routine.

The top section is my standard set up routine for the Tormach.

The middle section has some out of the way locations to try the idea so don’t get too fixated by these.   The important bit is the M98 call for the sub routine, the sub routine name (1001) and the number of repeats (the L5 for five repeats).

The last section is the sub routine indicated by the O1001.   The M64 command is specific to the Tormach USB Expansion board and it makes relay P0 in the box close its contact which in turn activates the Sherline CNC Rotary table to move one step.   The cutter than moves across to cut the tooth and then returns whereupon the relay drops out (M65), waits and then closes once more to increment the table.   Once five repeats have happened the M99 closes the sub routine and the program jumps back to the Z10 line in the middle section before stopping the spindle, homing and ending.

The joy of this method is that it is a simple edit of one line (the M98  instruction) to change the number of tooth cutting increments. I like it a lot.

Some fine tuning is still needed on the back and forth distances needed to clear the cutter through the wheel blank.

The normal test of the cut depth routine will still be needed before this could be run but once this is done it should be a sit and watch job.   Hopefully.

I have yet to run a wheel in anger so I will let you know how it goes. 

A compiled write up of all the related blog entries on this subject can be found on the downloads page.

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