Open Thinking when Solving a Problem

I think I have mentioned this before …. when you have different ways to solve a problem it is often easy to get locked off into a long winded but potentially elegant solution and miss the point.

3D printing has brought this home to me on a number of occasions.

An example – I have variable speed controllers on my Myford Lathe and Myford mill.   The controllers are identical and each have an ON and OFF push button.  The bezel around the ON button on one of these had cracked and come away leaving the switch floating in its mounting hole.

My first reaction was to replace the switch.  I contacted the controller supplier to ask for a part number and distribution source to buy a new switch.  They ignored my email which was fortunate as I would probably have ordered a complete new switch assembly.  I would then have had all the grief of stripping down the controller case and wiring in the new switch.   This would probably have invalidated any warranty etc etc.

Instead I stepped back and looked at the problem from a different angle.  The bezel while broken still had enough of the ring and thread intact and simply needed gluing back together.   However it would not have been strong long term.   What it needed was an outer strengthening ring.

Fusion 360 called and the Sindoh 3D printer.   A ring was designed and printed  (20 minutes) and the bezel strengthened and made good.   I also printed three more rings and put these around the remaining three switch bezels as a preventative action should they also weaken and crack.

A simple, low cost and effective solution with the added benefit of reduced downtime in the future.   But the point is that it wasn’t the first solution I was considering correct though it might have been.

3D printing is such a useful resource to have available but you need to think outside of your normal approach to a problem to realise its potential.

Sorry that wasn’t mega interesting but I thought it worth sharing …

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Sherline CNC Indexer on the Myford lathe

Some time ago I adapted a Sherline CNC Rotary Indexer to fit to my Myford Large Bore Super 7.   A recent request for details of how I did this has lead me to produce a write up for others to download.

Follow this link to the introduction page and download link.

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Tormach Tooling System and a Spanner in the Works

Tormach provide a rather nice tooling system for their milling machines.   This is known as the TTS.   There is a master collet permanently fitted in the spindle.  If you have the automatic tool changer option fitted this collet is depressed by a compressed air driven ram.   This opens its jaws to allow grabbing of individual sub collets holding the tool of choice.

The great bonus of this system is that you can have all your regular (and not so regular) tools permanently mounted in collets ready to go.  Press the button driving the ram and push the next tool home.   This also means you can populate the tool table in the PathPilot CNC driver program with all the tool length offsets without having to measure each time you do a setup.

It does mean quite an investment in the sub collets.   These are available for all manner of capacities both metric and imperial either with fixed diameter grips or standard ER ranges.  There are also custom tools such as the Super Fly and Shear Hog plus fittings to take a Haimer shank.

What was always a fiddly job was mounting a new tool in a collet and trying to contra-rotate the collet tightening nut while holding the body.   This is now no more ….. I have just taken delivery of Tormach’s simple but elegant solution to this.

It is a ball race mounted in a block but a ball race that only rotates in one direction.   You simply push the collet shank into the ball race and it is gripped tight.  To loosen the collet you simply put it in from the other side.  Magic !

Now you have probably realised I am a bit OCD and like things in their place and ordered.   Having got the tool gripping sorted I would now need two spanners to fit the collets of my most popular ER16 and ER20 nuts.  That was one too many spanners for my liking and was tying up standard shop spanners (which also have their allocated place in the shop …. oh dear how sad is that).

Now I happened to have a strip of 50mm wide Ground Flat Stock sat idle and Fusion 360 was calling.  A quick drawing on Fusion delivered a customised spanner sized to suit the two most popular sizes of collet I use.    I ran the CAM and off to the 440.

I put a piece 6mm hardboard on top of my tooling plate and put a couple of M8 holes at 75mm spacing on the centre line of the stock and fastened it down through the hardboard into the tooling plate on the 440 bed.   I made sure the Z clearance was OK for the screw heads (important !) and hit go.

It was the first time I had machined GFS and the 440 handled it well.  I now have a nice customised spanner hanging on the wall above that fancy bearing block.

Disclaimer : –  This post and many others on my website feature references to Tormach and its products.  I have no connection to Tormach Inc financially, commercially or otherwise.  I acknowledge that Tormach®, Tormach Tooling System®, TTS® and PathPilot® are all registered trade marks of Tormach Inc.

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New Welding Table – BuildPro Fixture Point

Got a bit frustrated trying to practice welding with a half baked working position so I splashed out on a BuildPro Fixure Point table and I have to say I am impressed.

TIG welding, FixturePoint, stronghandtools
FixturePoint Welding Table with Modular Fixing Kit

The concept is good in that you can have the welding surface sat directly on an existing workbench area or you can fit the supplied legs and make it a stand alone table.

Working area is 90cms x 60cms (just under 3′ x 6′) and the working surface has 16mm tooling holes on a 50mm matrix.

The kit comes with a starter set of clamping parts designed to fit the 16mm tooling holes.   You can opt for a square or round tubing holding version.

modular fixing kit
Tooling Kit as supplied with the table

The product comes in from Strong Hand Tools in the US and is marketed in the UK by Clwyd Welding Services.  The quality of the packaging was excellent and delivery was next day by TNT.

What I love about it is that the feet are inset on a 80cms x 49cms matrix and it just fits on my workshop mobile island.

I did a quick modification to my TIG torch holder to match the 16mm holes and I am now ready to blow more holes in pieces of steel with no excuse about my working position ….


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Milling Circuit Boards Update

I have made some good progress on taking a PCB design Gerber copper and Excellon drilling files into CNC.  I think it is worthy of a full write up but while that gets put together here are some comments.

First of all the conversion process using FlatCAM is very straightforward and I like the fact that you can default save your GCode startup and end routines along with other default settings.  Note that I had to scale the drilling data by a factor of 10.  Apparently this is not unusual.

The fun starts once you have code ready to run on the CNC.  The board design I was working on was a single sided copper design.  Single sided board tends to always have a curvature with the copper on the inside of the curve and the fibre glass outside (if you see what I mean).  This is probably the manufacturing process with the copper and its adhesive ‘pulling’ the board.

Double sided PCB tends not to be so bad in this respect and the effect is balanced out by the two coatings.   My board was therefore much more bowed than a double sided one.  (Incidentally FlatCAM allows for double sided board designs).

If you think about the geometry of what is going on it is critical to make sure the PCB material is flat on the milling table.   The greater the included angle of the milling cutter tip the worse things get if there are variations in surface height.  A height variation equates to a widening of the tool cut.  See the image below. (Not to scale).

I initially used 6mm MDF as my sacrificial backing board to protect my tooling table.   When I checked the MDF for flatness with my Haimer I was disappointed with the result.  Increasing the MDF to 12mm made a huge difference and good enough for the purpose.   This could have been a different manufactured MDF so the change of size is not definitive.

Initially I clamped the PCB to the MDF with a number of woodscrews around the periphery.   On checking with the Haimer this was not good with visible variations that I could impact by pressing on the PCB surface.

Next step was to replace the woodscrews with strips of 10mm square aluminium with a 1.5mm step on one edge.  These were screwed to the MDF on all 4 sides of the PCB blank and this dramatically improved the flatness to a point were it was adequate.  Pressing the board surface did not change the Haimer readings.

Flatness having been solved I addressed the cutter problem.   I had ordered some 10 degree included angle cutters from China but while they were in transit I got to talking with Think & Tinker in the US.   They were incredibly helpful and suggested that I should consider a 60 degree included angle cutter with a 5 thou tip.   They also suggested I try their lubrication to improve the cut quality and to also help protect the tool from wear.   Their tools also come with a fixed collar which means you can change out the cutter without having to reset your Z zero.

This 60 degree cutter worked a treat and the results were startlingly good.   I did not use the lubrication from T&T but instead used my normal FogBuster fluid (QualiChem ExtremeCut 250C) on a gentle repetitive puff.  This seemed to work and kept the dust damped as well as improving the cut.

While I could run the spindle at up to 10,000 RPM, I kept it down at 6,000RPM with a cutting speed of 3″ per minute (75mm).  I had a Z clearance of 0.1″ and depth of cut of 0.005″.  (Sorry for the mixed dimension standards but PCBs tend to be designed in Imperial but I prefer to work in Metric).

After the milling of the copper was complete I drilled all holes at 0.6mm (24 thou) using a carbide drill sourced from Drill Services of Horley (UK).  This was simply a change of tool, registering the tool length and loading the drilling GCode produced by FlatCAM.   The drilled holes were spot on dead centre in the copper lands.

In closing I would like to say how impressed I have been with the Tormach.   I had milled the copper one day and switched off for the night.  Next day I switched on the mill and absolute referenced XYZ and put the drilling tool in the spindle and hit go.  The holes were smack on dead centre in the lands without having to tweak anything.

It has been an interesting challenge that my friend had set me and he has gone away with a good looking PCB and my knowledge base has improved which is what it is all about.


A more detailed write up to follow.

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