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Member postings for John Alexander Stewart

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

Thread: Back to Imperial
18/09/2021 13:15:36

Over here in Canada, I'd love to be able to purchase more material in metric. Unfortunately, the local metal suppliers have told me that supplies come from the USA, so if I wanted some (eg) true-metric round brass rod, it would have to be ordered from Europe. We, although a metricated country, are surrounded by lovers of the inch.

I'm sure it'll work the same way for Britain - you are surrounded by metric; importing inch-based things from the USA will be more expensive than metric from more local suppliers.

(yes, there are mail-order suppliers of metric metals, but expensive including shipping and import duties. Fortunately, metric fasteners are becoming more popular and available locally)

Thread: origin of CAD
10/09/2021 22:33:12
Posted by duncan webster on 10/09/2021 22:04:21:

Probably got the processing power of a wrist watch today

I do remember going to the then supercomputing centre (RUS) in Stuttgart, when people there were research buddies, and, in one bar area, there was a liquid-cooled CRAY (CRAY-2??) computer, wiring visible through the plexiglass covers, and it was used as a table for standing around drinking beer, the power supply bench surrounding the cray CPU was, well, a bench for sitting on.

The chief buddy of mine said something like "it's only a couple of years old, but cost too much to run, so it was re-purposed".

I'll tell you - it was *very* weird using it to hold pitchers and glasses of beer while we stood around socializing...

I did have a nice little SGI Onyx-2 computer (a purple cube about desk height) that I got from a department that did not like the $10,000 (CAD) yearly maintenance fee, so I used it for a year or two off-contract. Eventually, my early Linux computers worked faster, but were not nearly as neat, and it was sent to "crown assets" for recycling or selling on.

Changed times... for the better in my opinion

10/09/2021 12:39:14

I'm with SOD - vector math has been around for millennia. Quaternions for at least 150 years. Bresingham's line to pixel algorithm came out when I was still in diapers.

Maybe I'm biased, though. We see history through our own experience and yours might be *very* different than mine. I spent quite a bit of time on writing code for 3D graphics rendering when working, and I see CAD UIs as just one way of generating 3D data for rendering. (the graphics code I wrote/managed is/was open source; for a bit was distributed by Apple in the days before the App Store, downloaded millions of times; some funding came from the US DOD, and likely still is the most used and longest running open source project managed by the Canadian Federal Government)

Thread: Steam operated drain cocks
14/06/2021 02:27:49

I made some from the US model engine maker from a long time ago. I made my copies about 10-15 years ago now.

Work great! Piston valve engine, so wanted something that would act as a relief valve if required.

The one Hans shows above would be better than the ones I made; rather than annealing brass disks, the o-ring makes it simpler.

Great little addition to a locomotive.

Thread: Recycling of Wind Turbine Blades
17/05/2021 15:26:47

I don't know. It takes energy to get the materials to make them, then energy to make the blades, energy to move them, to place them, to remove them, to ship them back, and, finally, to take them apart.

Might it not be easier to just use less energy?

I know that it's not a popular view these days; the current trend seems to be using more energy to solve "the climate crisis".

Gosh - that reads like it's a "Baah Humbug" moment!

Thread: Masso CNC G3 - Worth the price?
14/05/2021 12:43:53

Ed - thanks for the write-up.

I've got 3 CNC machines here (although one is a little Sherline lathe, was going to CNC an Emco Compact-8 but never got around to it so sold it on)

All 3 machines have small dedicated PCs running LinuxCNC with Mesa cards. Only a trackball-mouse as input, no keyboard. Right now, no network. I take stuff via USB from my office to my workshop. Machines boot on power, so I turn on power to the machine, it boots. All 3 computers have identical hardware.

Two have been running for years, no issues, although work/life has taken me from the workshop quite a bit over the last year or two. The Sherline lathe is the one that has not had much time; currently no spindle encoder. (was thinking of just taking a MASSO one from Sherline and using that) so not a lot of experience with a dedicated lathe, unfortunately.

LinuxCNC did go through a bad spell - real-time modules changed, and the new one is not (from what I understand) that great with the old parallel port one-byte-at-a-time protocol.

I think that, our small club here in Ottawa, of those with working CNC metal working machines in their workshop, 100% are LinuxCNC.

Each to their own, of course, there's no 100% correct solution to anything.

Thread: Sherline
22/04/2021 14:47:39

Dave - if you (or anyone else) wants to see what can be done on Sherline equipment, have a look at:

Chris and his Kozo Shay build

over at This fellow hails from NY state in the USA, and makes more in a day than many of us make in a year.

I made an "old Shay" from Kozo Hiraoka's plans; mainly on an Eco Compact-8, so when I followed along on how he made the "new Shay" on Sherline equipment (including cutting gears from brass) needless to say, I was both humbles and impressed.

22/04/2021 13:00:36


I, too, have a Sherline CNC lathe and mill. They were purchased for a potential house downsizing (moving to a smaller place), but that's been put on hold because of COVID, so not used as much (yet) as I had originally planned.

I've got bigger CNC mills, and use the same software. I've actually got 2 sets of software; I use Linux for work from home and one of my desktops, I also use Apple computers for software development. So, saying that:

On Linux, CamBam, and QCad, CamBam can do some lathe CAM, which has worked well with the Sherline lathe.

On Windows (which probably has not been booted in 6 months) Alibre Atom3D, and, if I remember the name correctly, Meshcam.

I just never turn on the windows computer, the Linux one is booted 24/7, so I use the 2D CAD/CAM system 100% of the time. I have tried (successfully) to run Windows in a virtual machine under Linux; it worked, but is slow and not as responsive as I'd have liked. The 2D CAD setup does things well enough for the parts I'm making.

Hope some of the above helps! John

Thread: "TINKER" tool & cutter grinder
09/04/2021 14:03:31

Wandering a little bit here.

I had a Tinker once - made by a Frank McLean, who wrote in Live Steam and has a book of his articles available from Village Press. He was the first tool designer and machinist for Lee Valley, some here might recognize the company.

I actually never used it - shortly after I purchased it, I had to move around the world (to NZ) for work; lent it and some other tools to a fellow club member who was very short of retirement funds, who subsequently passed away and the contents of his workshop auctioned off to other club members. When I returned, I found the workshop equipment I had lent in other peoples' workshops, and they had paid $$ for it so were not returning it.

Long story short - I built a Worden, 100x better, and I'd think Harold Hall's jigs are equal or better than the Tinker, if you want to use a standard bench grinder as a base.

Thread: CNC - What's the Problem?
01/04/2021 13:22:49

I use CNC extensively in my workshop. (when I get in there, that is!)

I figure that it is like the change from making parts to fit, to making parts that fit. No longer any need to stamp mating parts for assembly, the parts just fit.

Look at the Sherline CNC products, although they have gone now to an expensive CNC controller. I do have a CNC-ready Sherline lathe and 5400 mill, but have only used them for manual machining at this point. (have 2 cnc mills, a KX1 and a larger one, both LinuxCNC driven, that work well)

I am a real fan of LinuxCNC; each mill has a small computer with monitor and one of those track-ball mice things (no keyboard) so they are self-contained. When I turn power on to the electrical socket for the mill, the computer boots in a few seconds, and bobs' your uncle - ready to go.

Thread: Are we being listened to on the phone
27/03/2021 13:42:37

Just for the fun of it - circa 2014-2015, when the organization I worked for was in upheaval, I was asked (an Internet protol and app guy) to work with RF frequency guys to put forth ideas for increasing throughput on cell phones.

Anyway, I created this picture - Wired magazine with Andrew Snowden on the "cover", and a utility to show where tracking connections went - I figured that about 80% of the data transported was "fluff", 20% real-user-wished-for data.

Needless to say, the report was thrown out - these RF guys wanted RF ideas, not caring about the amount of data.

I'm sure the tracking, etc is much worse now. The red names are the sites that the tool reported as being "fluff"


Thread: Gravity and Weightlessnes
19/03/2021 13:20:40

"You are decending by vertical lift into a very deep coal mine and the only light is from a safety (Davey/Stephenson) lamp. The rope fails and the cage free falls to the bottom of the shaft. What happens to the light from safety lamp before you die? Comment: This has everything to do with gravity and weightlessness"

In the absence of "gravity induced" air flow, the lamp would go out. Now, how you'd have oxygen and no air flow in a vertical lift in free-fall, *that* is an interesting question!

Another interesting question - if you have liquid fuel, are in free-fall (say, in geostationary orbit) and are "weightless", how do you fire up a rocket engine? I mean, the fuel will just be floating about, not waiting at the bottom of the tank to flow into the engines...

Thread: Updating KX1 to USB or Ethernet Controller
25/01/2021 15:12:14

My KX1 has been running with LinuxCNC, a Mesa 5i25 and a Gecko G540 (parallel version) for about a decade so far.

Both of these products now come with Ethernet connectivity, if you want to go down that route. The Mesa 7i76 card has (if I remember correctly) 5 step control outputs, so you can have x,y,z,a and spindle if indeed that is what you require.

Do you really require a pulse stream for the spindle? Mine has a board inside that drives the spindle from a 0-10v isolated input - here is a link to the control board: little machine shop board. I know it's the same board because LittleMachineShop used to distribute MY old blog info with this board without attribution. sad

(The KX1 I have came without control electronics, (had steppers, limit switches, spindle speed control board) the late John Stevenson and I discussed this via email, and it seems mine was an "internal to China" model, so I just added it all. Spindle control was via the typical 0-10v input as stated above)


Thread: How to Search for Text Inside Multiple PDF Files at Once
21/01/2021 15:24:33

I keep finding Windows amazing. I'll admit to not using it much, because I seem more comfortable with Linux and MacOS on my desktop machines.

On both Mac and Linux, if you have searchable PDFs (i.e. ones with text, not just a giant image) all one needs to do is to open the file finder, and in the search box, type the text you are looking for. Voila.

It's so simple, so useful, just to search all files for the text.

Or, did I miss something? Likely, knowing me.

Thread: dual boot Dell laptop
14/01/2021 20:13:03

Assuming both are on the same physical disc. Boot in Linux.

Open a terminal window. type:

sudo update-grub

should do it. It should find the Windows partition, and put it in the GRUB boot sequence. This is the "boot loader" that runs when the system boots. Linux will find Windows, Windows will not find Linux. Of course.


If you have differing "boot bios" UEFI settings, tell me. I had to do this a little while ago - my Windows disc was installed in "DOS" mode, my Linux in UEFI, and I had to (simply) re-do the Windows one to be seen as UEFI. I'll see if I can find my notes. I had 2 discs; maybe if you have only 1 this might not be a problem. (I'm NOT an expert here!)

Thread: Linux CNC
01/01/2021 16:58:26

I run my 3 LinuxCNC based machines on old intel D525MW boards; 4gig RAM. These are dual-core 1800 mhz (or so) boards.

I have a MESA 5i25 card in each of them. In theory, they are identical for quick swapping.

Bazyle - stepper timing is fairly critical; using the "old, dumb" parallel port requires pretty exact timing; if you use a card that off-loads the critical timing stuff, almost any computer will do. (card can be plug-in, or via ethernet)

The MESA 5i25 cards (if you go that route) are pretty much plug-n-play, but be sure to order the one you wish; they are "flashed" with a configuration to match the attached device. I've re-flashed one; quite easy. 2 of my cards are for "parallel port" to Gecko G540 stepper driver boxes, one to a "Mesa 7i76 I/O card".

I did start a CNC conversion of my 2nd Emco Compact-8 lathe, put on a 3-phase motor, but work got in the way, and I inherited a little Sherline. 2nd Emco sold on, but kept the 3-phase.

You can find articles in Model Engineer by me, designed to show simple 2D CAD to CNC to actual parts; I don't have the issue numbers at hand. (yes Jason, 2D CAD; hopefully as a first step to get people going with CNC)

Of possible interest: I don't have a pillar drill anymore, but have 4 vertical mills. One of my CNC mills, if I want to manually drill, I just use that. It boots quickly, spindle control is a breeze, and I have a DRO if I want it for accurate manual placing of holes.

In my workshop, these LinuxCNC things just work. I don't worry about them; they have proven themselves incredibly reliable.

Keep going gentlemen! Hopefully 2021 will bring CNC to more of our workshops; whether LinuxCNC or some other program doesn't really matter. It's the learning and experimentation and production that matters.


Thread: CAM software for CNC Lathes - With C axis and constrained live tool
30/12/2020 21:23:48

Joe - the Real Time package for Linux has changed; as LinuxCNC (especially if driving one of the inexpensive breakout boards) needs realtime so that signals come and go without varying latency. It seems like it's fairly settled now.

That first ISO, on the top of the page is one that I would use.

Just download the iso, burn it to a USB, and boot. You should be able (if it is as it was) to run LinuxCNC directly, without installing it, just to test drive it.

32 or 64 bit - don't worry about it. Try that ISO on the top of the page.

(Am I pushing? Well, Tormach went from Mach to LinuxCNC-based software, and paid $$ for work on the trajectory planner in LinuxCNC, so why not use what a successful company uses?? They also use MESA hardware, so you are following fairly closely a known, successful path)

30/12/2020 17:50:24


on all of my machines, I use the MESA 5i25 cards. I use the parallel ("printer" cable option.

On one machine (a small CNC lathe) I use a Gecko G540; on my older Seig KX1, the same.

On my larger mill, and ex-project CNC lathe, a MESA 7i76.

(I hate giving advice, so use your judgment )

I think for you, a MESA 5i25 and 7i76 combo. It gives you lots of stepper outputs, lots of signal outputs, inputs, spindle encoder, "0-10v isolated" spindle control, etc, etc. Way more i/o than you'll need, but better too much than too little. You've got the brains to figure out a) what you need i/o wise, and b) what else you can do once you have it running.

There is a "plug-n-go kit" for the combination:

Anyway, my 0.02c - it's what I use and I find it well supported and incredibly reliable.

And, if it matters, my 3 machines are running an old Intel board, dual-core, obsolete from about 6 years ago; more than enough power to run the machines, with i/o, MPG controllers, touch probes, 4th axes, and so on.


30/12/2020 15:16:12


lists an ISO download.

I do know that there was an issue going from one real-time kernel to a newer one; this gave the LinuxCNC team a bit of an issue. Looks like it's solved.

Note that with "smart" cards like the MESA ones, perfect real-time is not required; with the old parallel port, servicing that port did require quick and timely response. (I use the MESA cards in all of my machines)

I can fully understand the frustration when LinuxCNC was going through that real-time transition, but with an ISO, maybe it'll install nicely. Knowing what I do from seeing your work here, I'd expect that once it is running, and you comprehend the flexibility, you'll be very happy.

Whatever you do, keep doing, and (especially) keep posting!


29/12/2020 20:12:14


As you may not (yet) know, Tormach PathPilot is basically LinuxCNC with a simple install and conversational programming -enabled GUI by default.

The potential issue is setting the correct ports/cards for your system; Tormach sells it configured for their machines. They have a new lathe on the market.

It used to be (have not looked at in a while) that it used MESA cards; I'd assume it is still the same.

Last I read, you can get it on a USB stick. Maybe worth a look, and a web search for others using it.

By the way, yes, LinuxCNC seems to have gone through a bit of a rough patch with documentation and install, but once you figure it out, the thing *just works*. Incredible piece of software. (I have 3 machines with SSD drives and dedicated computers; flick the power switch by the machine, the PC boots, and you are good to go)

One of my mills, with a two-step pulley system on the spindle; I have it automatically figure out what "gear" it is in, and adjust accordingly, thus if you ask for (say) 1,000 rpm, you get it, as close as the sensor, etc, can get it.

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