Woody – Page 43 – Woody's Workshop

June 16, 2019June 16, 2019

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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May 23, 2019May 23, 2019

A Spanner in the Works – or simply a Stick

From previous posts you will be aware of my involvement maintaining the local church clock. Over the past months my colleague and I have been nibbling away at various little problemettes with the movement and things are now looking quite good. For the past two weeks it has run sweetly and maintained +/-1 second over that period.

Then last night it stopped.

This morning we wandered round to see what the problem might be. The first thing we do on arrival is look at the front dial to see at what time it had stopped. This time it had stopped at around 10.35 last night. We climbed the tower and inspected the movement.

There did not seem anything obviously wrong so we decided to swing the pendulum and get it working again. We had arrived at just before 10am and our inspection took us over the hour and the front the dial was showing 10.35. Because we were now ‘within the hour’ it was acceptable to wind the hands back to the correct time which was now just after 10am.

I pulled out the motion work locking pin and began to move the hands (which were now independent of the movement) in a backwards direction to set the time. Except the hands would not move backwards. There was resistance. Something bad had happened to the motion work.

We checked the mechanism to both the front and rear dial but there was nothing obviously wrong but the hands refused to go backwards under light pressure and I did not want to force anything at this stage.

We went outside again and this time checked the front and now also the rear dial and this is what we saw : –

Our feathered friends had built a nest on the belfry window ledge and a stick had fallen from the nest and jammed itself in the dial. The odds of this happening must be pretty thin.

A careful waggle of the hands back and forth broke the stick free and we then reset the time and hopefully all will now be well.

The interesting observation was that the stick was only brushing the hand in the forward direction but in reverse it was pushing against it. The forward resistance was still sufficient to reflect back through the motion work into the main mechanism to stop the escapement and therefore the clock.

Another bit of knowledge gained.

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May 21, 2019May 21, 2019

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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May 19, 2019May 21, 2019

Droning On and another Toy

Another drift to the dark side I am afraid.

I bought a drone.

Yes I know ….. Lots of reasons why I justified it to myself and I went through the prior post decision making process and got a ‘yes’ as a result.

Seriously I have been considering one for sometime. In France the house sits looking out over a valley and we often see deer and foxes (but not yet a wild boar) and I have always hankered for being able to get up close to them. France aside my work on turret clocks often needs a close view of the clock face without the hassle of ladders and scaffolding. So two good reasons (in my book anyway).

I had been watching the market trying to decide when to jump. The two big players for the semi professional market are DJI and Parrot. Both these run out expensive. Then in January I got a mailshot from Banggood about a new device to be launched by Fimi called the X8 SE. This seemed to be only available from Banggood and was on back order status. I missed out on the first delivery but finally my toy arrived last week.

It is amazing. And at a fantastic price.

Not ever owning a drone before I cannot compare with anything but it is so easy to drive and has so many automated flying routines. Battery life is around 30 minutes and range is stated as 4km and it can skim along at 18m/s speed (yes that is 65km/hr ….). It does 4k video and 12M stills.

So that is my entertainment sorted for summer, should summer finally arrive.

fimi x8 SE drone and controller — Fimi Drone and associated controller.

It is worth watching Dustin Dunhill on YouTube if you want a serious review of the device. He does tech reviews and there are 3 or 4 Fimi videos on his platform.

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Droning On and another Toy

May 10, 2019May 19, 2019

Decision Making Process for buying a New Workshop Asset

While reading a hobby related magazine I saw the following note that I think speaks volumes …..

When deciding whether or not to buy a new piece of kit for the workshop ask yourself three questions :-

Do I need this tool ?

Do I want this tool ?

Can I justify this tool ?

If the answer to any of the above is ‘possibly’ then buy it.

If the answer to any of the above is ‘no’ then ignore it as it is probably a statistical anomaly.

If you feel you cannot afford to buy it then tell yourself you are in danger of becoming a cheapskate and buy it anyway.

Enough said ?

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