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Member postings for John McNamara

Here is a list of all the postings John McNamara has made in our forums. Click on a thread name to jump to the thread.

Thread: Plans for updating the archaic forum?
16/02/2021 08:26:12

Hi All

If the current discussion was about the interface with the users, for example improving the methods used to upload images; Some platforms support "drag and drop", that would be a worthwhile improvement. Making the program easier to use is a worthwhile objective.

However the current font size and the grey background is easy to read. Please don't muck about with it without very careful testing with users.

This is a commercial website as well as a great (and free) forum. The advertisements are an important part of the websites continuing success, advertisements occupy the right hand side of the screen OK to me. On the left the poster name and stats, so far so good.

What concerns me is as shown in some of the examples shown in this thread the width of the left or right columns can dominate the available space, squeezing the hard to read small and pale text of the actual posts into a small space.

If there is going to be changes a clearly defined need for each change must be documented taking the end users point of view and the commercial imperative into account.

So who will get the job to "Fix" the program ?
Management will often pass the design to the web programmers. This can be a big mistake! Savvy computer users are not typical users, what appears simple to a power user can be quite daunting to a less experienced user. Testing and retesting with typical users is essential.


Edited By John McNamara on 16/02/2021 08:28:33

Thread: Facing parallel between centres.
13/09/2020 06:56:28

One way to face two sides perfectly that has worked for me in the past is to:

First face the work piece both sides in the three or 4 jaw it does not mater. then drill and centre one side of the workpiece.

When you take the workpiece out of the lathe chances are that it will be a little out of parallel even if you set it up with a dial indicator, it will probably be a few tenth's out.

The next step is to place a piece of scrap in the lathe and then face the outer edge say 10mm then turn a recess in the centre say 10 thou deep. leave this piece in the lathe. It will be perfectly true.
ithin the limits of the spindle bearings If you want to be technically correct.

Then hold the non centred side of the workpiece and centre it up with the tailstock centre pressed firmly against it and locked. This process works better with a ball bearing centre. Another possibility would be to bolt it through the spindle to keep it pressed against the fresh turned surface.

The last step is using a fine light feed face the centred side, you will leave a small unfinished section in the centre, this can be removed with a file if need be. You should not need a dog if the workpiece is a reasonable diameter. friction will hold it

The method also gives limited access to the back and all the side of the disk. Probably enough to do a riser in one sitting. if you plan it well.


Thread: Mystery Object ... This one has me beat
12/09/2020 07:32:31

Yes I know this is a segway... assuming the part is a survey mark

It's Been a while since I posted on this forum. The past couple of years have been very hectic.
Next Wednesday we pick up the keys to a new house. After 38 years in one house we are moving to the hills about a 45 minute drive from Melbourne.

I wish to build a new shed and in order to do so the council requires survey, I was on site when this was done in order to discuss the location. And yes the EPOXY CNC mill post on this forum will continue when the shed to house it is built.

A Land survey starts not at your property but at the known reference points in the area. One of those points was in a council field nearby, about a foot below the grass! Using the very accurate GPS station that surveyors use he had no problem locating it. The surveyor told me that there are many of these hidden reference marks around the city. The importance of the mark determines how it is founded, the more important ones may sit on hidden but massive concrete foundations.

Thread: Mechanisms in modern engineering design Artobolevsky
14/01/2020 12:50:44

Hi David George.

If the mill was running I would have shown it here.
My posts re the mill are up to date.
Alas it has had to just sit there reminding me. Hopefully I can get back on it soon.


14/01/2020 05:40:39

Hi All
Yes I know I have not been around here much.
2019 was a pretty tough year, a high workload and a fair smattering of other issues.

Anyway back to the topic. There was a time when elaborate mechanisms were time consuming to build and therefore costly. Creating complex shaped parts has now become a very much automated process. From CNC laser and plasma cutting, CNC punch pressing, CNC metal machining machining to microns if necessary, all created with CAD CAM Design.

There is a shortage of contemporary published books on Mechanisms. And those that are published tend to feature reprints of older authors.

Those old books may be more relevant to today's engineering needs than you think.


Edited By John McNamara on 14/01/2020 05:41:00

Thread: MSMEE Exhibition Melbourne Video
07/10/2019 07:28:53

Hi All
Link to a well prepared video of the Expedition Prepared By Arron Powter.



Thread: Machine alignment using low cost electronics
22/09/2019 08:28:16

Hi All

I ran further tests with a new webcam, outstanding results!

This project keeps getting better.

See the end of this post here.



Thread: Anthropocene
22/09/2019 04:54:39

Not all of the images in the presentation represent catastrophe, precipitating Lithium salts by solar evaporation in ponds in a very arid area of Chile to me is greenhouse gas positive when it goes into electric storage batteries that replace carbon based fuels is a good thing. Not all industrial processes are bad.

The large scale production of food is essential to the survival of most but not all of worlds population without the terrible famines of the past. Regrettably Famine still exists, driven not by lack of food production, but by despotic politicians, not all of whom reside in the third world.

I think the images are a good thing the good, the bad and the ugly all equally represented.


Thread: CRT Free!
14/09/2019 09:32:27

Drill a hole in it!


Thread: Machine alignment using low cost electronics
06/09/2019 16:25:03

Hi Michael
I sent you a Gmail and a PM

01/09/2019 11:05:11

Hi All

I Just uploaded some further results from my experiments here: **LINK**

I am rather pleased with the results and there are further improvements possible.


Thread: Equity release!
31/08/2019 11:02:06


I think the first consideration is the math on life expectancy, According to the UK census at a current age of 70 the average life expectancy is another 14.77 years as of the last assessment made a couple of years ago. This number is the average only, many people beat the average a few by decades.


I think any plans for the future need to take these statistics very carefully into account.

Being caught short a a vulnerable state of age when planning could have avoided it is a very unsatisfactory state of affairs.


Thread: Machine alignment using low cost electronics
28/08/2019 03:58:52

Thanks Michael I responded with an email.

27/08/2019 01:28:53

Hi All

I Bumped this post because there are some worth wile changes.

There is an executable version available, A Jar file so you will need the current version of Java installed.
If you have a webcam preferably one with a lead attached not the one in your laptop although it will work. it is all you need to experiment.


The program code for the latest version has also been updated on Github for those that can program.

Edited By John McNamara on 27/08/2019 01:32:56

24/08/2019 12:55:12

Hi Andrew

I meant to say this as posted at the other place

"Now for the exciting part; Hidden at the bottom of the Gaussian graph there is a tiny numeric value, It followed my indicator movement when I moved the slide. very roughly a value of 1 to 4 on the graph value to 1 to 4 ticks on the 0.01mm indicator. I assume this correlation may not have been planned however with the particular camera I used it was very convenient.

I ran the test several times and it was repeatable.
0.01mm is equal to .00039" (about 4 tenths)
A very good result from a crude setup."

There is an error in the scaled value that needs to be explained. The dial indicator readings and the values on the screen correlated and were repeatable.

Hi Clive

Yes there is more work to do on this project, For a start I want to use the sensor to work with backlit .008" stretched wire without a laser and no lens, just the shadowed area of the wire on the sensor. I am working on something I intend to show at the MSMEE Exhibition in Melbourne in 5 weeks.

You are right using a modern PC enables number crunching speed unobtainable not that many years ago, T 640x480 webcam came from the junk bin. Now 1080p camera modules are dirt cheap some under 20 dollars

The colour image is converted to grey-scale by the software. 

I will keep working on this project.


Edited By John McNamara on 24/08/2019 12:59:40

Edited By John McNamara on 24/08/2019 13:06:43

24/08/2019 10:24:42

Hi All

I stumbled upon the following post on another UK forum.

"DIY laser leveling using webcam and laser level."

The poster provided a link to the software source code on Github
It creates a Gaussion graph of position, I tested the software using a crude test setup.

I obtained repeatable accuracy of 0.039mm (.0004" and I am sure that can be improved with a better setup....... remarkable.


Thread: Hieroglyphics on a Wehlen & Co clock face
13/08/2019 09:21:46

Hi Sam

I know that modern watch faces are often Pad printed. (As well as billions of bottles and the like) It works well on curved surfaces.

I also read somewhere that this process goes back 100 years?

I wonder if the raised text might have been done by this process or a similar process.

Here is a Search that revealed a few good links......


Thread: Black Oxide coating
12/08/2019 08:59:25

Hi All

One of my treasured books.

Howe does an outstanding job describing formulas on metal and wood finishing.
Also high precision toolmaking in general from an old school manual perspective.

I bought mine many years ago. for the tech info, The gunsmithing part is secondary.



Thread: Colchester Bantam gear spline profile?
09/08/2019 09:42:56


My first lathe was a vintage Colchester it was a version of this one. I was very sad to let it go due to lack of space.
It used splined centers for the change gears.
That looks like a very nice set in good condition. There should be a 127 tooth Gear.

The flat belt driven black japan finished lathe second photo down. **LINK**


Edited By John McNamara on 09/08/2019 09:44:16

Thread: DIY Epoxy Frame based CNC MILL
08/08/2019 10:57:35

Hi all

I test fitted and aligned the X axis saddle that carries the Z Axis today. Those following this post will remember I set the gantry yesterday using a 0.01mm dial indicator set against two bearing blocks. With the carriage in place I was able to use a straight edge allowing me to test the full travel of the carriage. there was a 0.005mm error in the height. No problem, I tweaked the height of the gantry casting to reduce this to less than 0.001mm along the full travel. Remarkably this was better than the accuracy I obtained setting up each rail individually, that was using 1 bearing block. The saddle is mounted on 4 bearings. Averaging must have worked in my favor. I am very pleased with the result.

Testing the X Axis travel height.

This photo shows testing the X axis travel near the tool in the horizontal plane.
Remarkably no adjustment of the alignment done yesterday was necessary.
The indicator moved less than 0.001mm

Once the table is made It will be installed and tested in a similar manner.


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