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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French Connections, House Numbering, Shed Building, Left and Right Hand Threads

Sorry it has been a bit quiet but we had three weeks in France albeit with not the best of weather.  As ever a few jobs on the list and some new experiences.

The village where our house is located has always had very ambiguous addresses such that deliveries were a nightmare unless by Post.    The parish council decided to solve this with a ‘numerifcation’ and tasked a local man to decide on street names.   Given that there are probably less than 200 properties in the whole village and very few of these in our road, we were surprised to be allocated number 436.

On arrival and taking a wander round the village the numbers appeared totally erratic and certainly not conforming to the norm of odds one side of the road and evens on the other.   It then dawned on me that the numbers were related to the distance from the starting point of each road relative to the village centre.  We were therefore 436 metres along the road from the first house.   A quick cross check on Google Earth confirmed this as the distance to the centre of our gateway.

Now you could label this as French perversity but I think it is rather elegant.  Deliveries can now find us easily and if someone does a barn conversion mid street a new unique number can easily be created rather than 6A or similar. The council provided us with rather nice enamelled number plates and these match the new street name boards.   We noticed on the drive home that one or two other villages we passed through seemed to have had similar initiatives.  No doubt Macron will claim credit.

The first test of the new address was when I ordered a garden shed (abri de jardin) from Alice’s Garden and it found us successfully.   The aim was to have a storage shed for our ride on lawn mower.   The shed was a bit on the low cost side but did arrive OK in two flat packs.   When opened up it all seemed a bit flimsy.   Two of our friends had arrived to stay and they got roped into putting it together.  The instructions called for two people and predicted 2 to 3 hours work.    It took four of us a bit longer than this and lots of self tapping screws later we had a shed. 

alices garden shed
Garden Shed from Alice’s Garden for ride on mower storage but with door too narrow …. another fine mess

Given the flimsy nature of the materials it was surprisingly sturdy. The one flaw in the plan was the mower would not go through the door …. I had measured across the wheel width and not across the cutting bed.  We left our friends with the challenge of solving this minor issue …. so far they have managed to widen the door opening and it now needs a new enlarged door.

We had also ordered an electrically operated sun awning and this was installed while we were there.   This is a seriously heavy piece of kit that the two technicians were struggling to lift between them.   The installation involved mounting three plates on the house wall and then ‘dropping’ the awning housing onto these with retaining fastenings.   Because of the style of block work used in France they tend to use chemical based fixings for anything substantial that needs mounting.   The technicians arrived, measured up, drilled and chemically bonded 12 lengths of M12 studding into the wall.   After the prescribed setting time they attempted to mount the plates only to find their logistics team had supplied them with left hand thread studding and right hand thread nuts.   Much French cursing ensued.   

Out came the angle grinder and the studs were chopped off.   Rummaging around in their van they found some more right hand thread studding, re-drilled and re-bonded this in place and finally got round to mounting the awning – which was a real struggle to lift even with three of us wobbling on ladders.   They didn’t leave until gone 7pm so not the most cost effective installation quote by the salesman.

awning in france also called a store
Awning in place with correct thread studding used

This excitement apart we had a good stay with a round of golf at Souillac, a village festival and an excellent meal with our neighbours and their extended family.   The house is looking pretty good now and perhaps next time we can just relax with nothing on the ‘To Do’ list – perhaps.

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The Gravity of the Village Clock

Some time ago I made mention of getting involved with the running of the village clock.   There was an added incentive as this was a Cooke of York movement dating back to 1869.  Anything associated with the  City of York is always of high interest as it was my birth place.  That is except the soccer team but I try not to get drawn into that discussion.

Back to the clock.  Myself and a colleague in the village have been working on the clock to bring it back to time.  We were getting pretty close.   Then it stopped.   Despite a few restarts it refused to run for any length of time.

We rolled up our sleeves and gave it a thorough visual inspection.   We were just about to leave it for the day when we spotted that the pins on the pin wheel on the gravity escapement arbor seemed very tight to the arbor supporting bracket.   Closer inspection revealed one pin of the five seemed to be slightly at an angle.  Even closer inspection showed a visible witness mark on the bracket where the pin or pins were rubbing on the bracket.   There was no mechanism to centre the arbor away from the bracket.   

We decided to remove the arbor complete with pin wheel, fly etc.   This was fairly straightforward.  A single screw at the opposite end to the escapement arms could be unfastened and the arbour came free.  Except it wasn’t that easy to unscrew as the screwdriver slot was very narrow.

Having got the arbor assembly back to my workshop I discovered two of the pins were lose, one of them to the point of falling out.   It seemed to have been held in place from coming out any further by the support bracket.   

I marked and numbered the escapement legs and removed each pin in turn, shortened each by 0.5mm, degreased the threads on each pin and its associated mounting hole and then refitted each one with a dab of Loctite to hold them in place. 

Spinning the arbor in my hand I could now see that all pins looked parallel and the length was much more consistent.  Hopefully the pins will now comfortably clear the mounting bracket.

The gravity escapement arbor showing the five escapement legs and the five pins that needed shortening

To make refitting easier I made a small hand tool to fit the slot on the mounting screw and used a hacksaw blade as a pseudo screwdriver blade to more easily turn and tighten the screw.

Since refitting the arbor the clock was running slightly slowly so we removed a penny from the weight tray and it now seems pretty much spot on.

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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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Cycloidal Cutters and Finding the Cutting Centre

It has been a thoughtful morning on the Tormach wheel cutting setup. 

In order to cut clock wheels the first step is that I need to be able to set the cycloidal cutter centre line accurately on the centre line of the blank brass diameter.  See the picture and description below.

Exaggerated mock up of the cutting setup showing a brass blank mounted on a super glue arbor and a cutter mounted in the Tormach Slitting Saw arbor. The centre line of the cycloidal cutter teeth sits on the centre line of the brass blank and cuts on the rear edge as seen above. After each cut the CNC rotary table increments the blank by one tooth ready for the next cut. (In practice the super glue arbor would need to be much larger in diameter in order to be more in keeping with the diameter of the brass blank and so ensure maximum support while the cutting was done).

From previous posts you will know I have got the chuck securely and centrally mounted on the CNC rotary table and this assembly is in turn rigidly fixed on the tooling table. The position of the centre line of the chuck is now fixed relative to the tooling plate on the bed.  The chuck and rotary table mounting bracket is sufficiently Woody over engineered to hopefully be repeatable.   Likewise the distance from the spindle to the chuck can be repeatably zeroed using the Haimer and its associated tool table entry (#90).

Expanding this a little, if I put my favourite piece of 11mm diameter silver steel in the chuck and bring the Haimer down to contact it, rock the Haimer back and forth in Y to get the steel diameter peak, I can get a Z zero reading to the top of the steel.   By creating a new entry in the Tormach tool table (#91) which is the Haimer length plus 5.5mm (the radius of the silver steel) I can use this virtual length stored as a new tool #91 to allow me to set the Haimer on the silver steel while actually giving me Z0 on the centre line of the chuck. So far so good.

As you might have read from an earlier post, the idea of using the Tormach Slitting Saw arbor to hold my cycloidal cutters would in theory create a repeatable tool length to the centre line of the cycloidal cutter teeth.   Having this as a tool table set up in the Tormach would simplify setting the cutter centre to the centre line of the chuck and therefore the  centre line of the wheel blank being cut. This is where the thinking drifted somewhat.   

I created a new tool table entry (#77) that was the length of the saw arbor to the shoulder that the cycloidal cutter fastens against.   I thought I could then follow the same routine as detailed above and add to this length the half thickness of the cutter and create a new tool table entry to match.  This would once again create a length which would give the centre line of the cycloidal cutter.

That was fine until I measured my tray of cycloidal cutters to see what the thickness of the cutters were …… sadly consistent they are not.   There seems to be no standard by manufacturer or diameter.   I have cutters with thicknesses from 3mm through to 7mm.   I could create a new tool table entry for each thickness but this is a recipe for a mistake when selecting the correct tool table entry for the cutter being used.

The simple solution I think is to use slitting saw arbor tool table length (#77) as the initial setting length to Z0 and then do a G0 Z-x.xx where x.xx is the half thickness of the cutter being used.   Once Z has dropped to this reading the Z axis can be re-zeroed to run the wheel in question with the cutter in question now sitting on its centre line on the centre line of the chuck.

Simple diagram showing the concept of using the Tormach tool table facility to allow easy setting of the centre line of a wheel blank and cycloidal cutter centre lines

I hope that all makes sense …. I could of course just eyeball it and not try to be so fussy but when you have the tools to make things easier you might as well use them.  I also need to look after my precious piece of 11mm diameter silver steel.

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