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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: tich
17/10/2018 21:05:29


I made a screw-down regulator for my large-boilered Tich. I did this back in the early '90s, and it has worked flawlessly.

I patterned it off of the Rob Roy one, used a coarse 1/4" tap and the valve end something like 45 degrees. I probably scaled it down to fit the regulator tube so as to fit in with the LBSC regulator bushing design.

Do it!

Sorry, no pictures, no drawings. It's never been out since first steaming.


Thread: Drill or Mill?
15/10/2018 18:51:46

I no longer have a drill press.

I have two mills with quills; both do fine for drilling. Actually 3; I just put back on the mickey-mouse mill/drill head on my Emco Compact-8 lathe. Easier to store it there than elsewhere.

Do I miss a drill press? Well, maybe once or twice a year, but I enjoy the space more.

The drill press was great for putting sanding drums in and sanding wood or polishing steel, putting paint-stirrers in, etc. Although it was a good name-brand, it still was not nearly as good as the quills on my mills.

I'm tending more towards 3-1/2" gauge, so having a honkin-big drill press no longer suits what I expect to do.

Just my 0.02c.


Thread: Sherline
19/09/2018 14:21:24

Steve - well done.

Sherline lathes seem like great lathes. A fellow over in the USA made a 1:16th Kozo Shay locomotive (the newer version) on his Sherline Equipment, in about 1/20th the time it took me to build mine in my much larger workshop.


Thread: Win10 Home / Linux LAN - anyone got one going?
14/08/2018 12:10:34

Hi Robin;

I have not responded yet; I sometimes have to use Win XP and Win10. This will not help, I expect, but:

1) WinXP, I run on linux on virtualbox, for my weekly timesheet submittal;

2) Win10 - the machine it's on is dual-boot; (actually, quad-boot) and if Win10 is shutdown properly, you can just mount the disc on Linux.

Possible thoughts for you?


Thread: Gear Hobber : Design ideas please ...
09/08/2018 19:55:04

Hi Joe;

Thank goodness everyone has different strengths - I enjoy (and, am envious of!) your strengths that you show here.

One of my strengths is the ability to develop software that runs internally on graphics chips, which means that I have to be able to easily write programs on Linux, Windows, Android, MacOS and IOS.

Of those, I find Windows obtuse, confusing, and hard to do anything on, compared to the others!

I think we should focus more on the ease of the end results rather on the specifics of getting there - there can be many paths to a destination.

Regards - John.

09/08/2018 12:32:06

Andy Pugh is one of the LinuxCNC'ers who cuts gears with a hob - one of his videos is linked to above.

He's very active on LinuxCNC (old name was EMC2) and is great at answering questions. Both on the mailing list, and on the online forum.

A link to a wiki entry:


Another youtube video:


The software's all there, and it's proven, if that is the end goal you want.

Thread: O rings for pistons
07/08/2018 17:50:45

Hi Duncan;

A note of support:

My little Tich has had Viton O rings in it, and on the valve spindles, for about 2 decades. They used to have graphite packing, but that "disappeared" when inspected for lack of power. Pistons re-fitted with O rings.

They have not been out since installation, so I can't remember the thickness of the rings, but I don't think it matters much.

As you'll know - a tiny bit of compression, and some space for "roll" and Bobs' your Uncle.

Have not had the Tich out since our track got the "frost heaves" a couple of years ago (REALLY steep grades between frost-heaved posts and those which did not heave) but I'd like to get it out again later this summer, as the club elevated track is getting well-deserved remedial work.

I think the Viton rings (brass pistons, GM cylinders) are 100% successful.

Thread: Designing Model Boilers (Thermal Design)
26/07/2018 18:20:37
Posted by duncan webster on 26/07/2018 13:14:21:

As regards water circulation, I can't see it makes a lot of difference to steam production, the problem is getting the heat from the combustion gasses to the tubes/firebox walls, not from the metalwork to the water. If there is a pocket at the throatplate where circulation is not good and heat transfer from the fire is high then the water in that area will boil faster, the bubbles will rise and more water will flow in. This might well give rise to localised temperature gradients in the firebox, which I do not suggest are a good thing, but in a small copper boiler where heat can flow in the metal very quickly, and distances are small I doubt it matters very much. There is plenty of evidence of Winson Britannias running with exposed firebox crowns with no ill effect, due to the bottom gauge glass fitting being too low. Again not something I'd recommend

Duncan (and Martin, of course); my expertise is certainly not in mech. engineering, but I do find it an interesting topic.

With the thermal conductivity of copper being that about 10x that of steel and something like 1,000x that of water, I do tend to agree with your observation of exposed crown sheets and copper boilers not being as much of an issue as we might think.

An interesting calculation would be to see what temperature an exposed crownsheet would get to in a small copper boiler, with girder stays or with round stays. Any takers? There are lots of thermal conductivity paths on our small boilers (stays and mud-ring and tubes and firehole, and...) so I do wonder what the limits might be.

I do think we are very cautious with silver soldered copper boilers - true, low water and a good fire will heat'em up, but when the water finally goes, so will the fire, as the blower will stop. Yes, it's better to err on the side of safety, of course.

As an aside, my (again, novice) observations and calculations are that a butt joint will be fine on a copper boiler, given proper silver solder penetration. One prolific club member does build copper boilers without flanged plates, and these are very successful.

Very interesting - thanks all. John.

Thread: fire warning
09/07/2018 12:40:19

As a kid, a friend's father was building change rooms at their outdoor pool. Roof not on yet, so he had clear plastic sheet over the rafters to keep the rain out, and off of the carpet below.

Of course, after a rainy day, the plastic sheeting filled with water, the following sunny day allowed pin-point tracking of the sun as a thin black (charred) line was found on the carpet that evening.

The roof was finished forthwith, but the char-lined carpet was left as a reminder.

(of course, first line of questioning was "what the h**l did you kids do THIS TIME??? for once, we were actually innocent!)

Thread: Workshop in this weather..?
02/07/2018 18:53:51

Workshop? Freezing cold these days. Air-conditioning running, cold air seeks the basement.

However, yesterday we had our annual "Canada Day" steamup - setting up a portable track, running, then tearing down said track. I think the temperature was something like 36 in the shade, with a "humidex" reading of 47.

Of course, 6 months from now, it'll be -36, with a "windchill" reading of -47.

If you are thinking "why do they do this, are they crazy?", don't worry - we are having the same thoughts.


Thread: WM18 CNC Mill Conversion
30/06/2018 12:43:44

I did one of these (but labelled "King Canada" using a ball-screw kit from a supplier south of the border here in Canada. Thoughts:

- the underside of the table needed grinding to give more room for the X axis nut;

- the dowel pin holes for the X axis end plates did not match my mill;

- the y axis kit assumed that the threaded holes in the castings were not off-kilter (sigh);

- the gearbox was noisy, so I obtained a belt-drive replacement from benchtop precision in the USA, HUGE difference;

- added ball oilers to all axes;

- I replaced the speed control with direct drive from my CNC bits, and used the tachometer bits to feed back into my CNC computer, to set and hold speed, independent of drive belt setting;

- I added a wired XHC HB-04 pendant - fantastic bit of kit.

Overall results?

The best part was (and is) the LinuxCNC computer code. All I use is a trackball and the pendant, no keyboard in site.

The worst part was the mill - I obviously got one put together from a kit of parts, the table was not flat, but humped down the X axis (could have been because of my slight relief grinding for ball nut) but there are hard spots on the table, and, I think the ways, so the accuracy at some points is debatable.

Thread: proxxon KT70 CNC ?
26/06/2018 11:36:03
Posted by john constable on 25/06/2018 10:01:42:
Wow. Arc kx1 is about 4.5k without software! That wont be happening be happening any time soon!

I have a KX1, which I got without controller, and added my own.

I run LinuxCNC on it, which is free and rock solid.

For engraving, LinuxCNC will read in a bitmap file (jpg, etc) and engrave.

I do use "CAMBAM" for CAM, but others use Fusion 360 for CAD and CAM, which is free. I did use the free DXF2GCODE for a while, but went for CAMBAM.

I use a little Sherline CNC rotary table which was not free, but does work well.

All in all, a great little machine. It just runs all day, doing what I ask of it.


Thread: Is embarking on any 7 1/4" loco other than madness ?
15/06/2018 12:09:47

Each to their own;

Many in our club are making large 7-1/4 locomotives.

My wife and I sat back a couple of years ago, she, the Accountant by trade and I did a back-of-the-envelope calculation on the cost of making our house 7-1/4 compatible, which came out to about 5 years of my take-home pay, plus increased annual costs (insurance, property taxes, 2nd vehicle maintenance etc). The problems of living in a city with cold winters a house not designed for this hobby....

I enjoy building more than running. Lots of 3-1/2" gauge parts almost being given away, or with Kozo Hiraoka's designs, just from raw materials.

So, big models are not for me in my lifestyle; but if they suit you, great. They are all fun.

(one of the models I have started is a 7-1/4 Stourbridge Lion, which will weigh in about 20 lbs more than my 3-1/2" gauge Continental, large, 2-8-2 - to echo/support Duncan's thoughts)

Edited By John Alexander Stewart on 15/06/2018 12:17:34

Thread: Cost and Weight: 3 1/2 vs. 5 gauge
11/06/2018 12:20:08


Another 2 points

- a decade or two ago, visiting the Waushakum track in the USA, I was very impressed with a Kozo Climax locomotive, built by a fellow wheelchair-bound;

- had a very good build log of a Kozo "new" Shay, by Chris Rueby (Crueby), built on Sherline equipment.

Here's a link for the New Shay build - but you may have to register to see photographs(?):


All small and light; it may give more ideas of what would work best for you.


11/06/2018 02:39:44


Ok - MY opinion. Others will disagree, of course.

I like 3-1/2. Reasons:

- strong enough to pull a couple of people;

- light enough to move; easier than a larger gauge locomotive;

- over here (Ontario, Canada) our club uses 5" gauge, but the norm is 4-3/4, so that's a bit of a "bummer", as one can not visit other clubs. You'll not have this issue, of course.

- elevated tracks, if you have it, are fine for either gauge, as reaching into the cab is then easy.

- ground level running - both are not nearly as convenient as larger gauges (7-1/4, etc)

- parts are smaller and easier to man-handle, and machine on a given machine.

- Just finished a 3-1/2" gauge Shay locomotive to Kozo Hiraoka plans - no castings! Beautiful plans....


Now, I do understand that many think bigger is better, and that I'm an odd-ball here. I do like running larger steam locomotives, but have decided that me building one is not in the picture.

I'd hazard to guess that the trend in North America is 7-1/2" (not a typo) gauge, and "diesel" outline, so steam is on its' way out.

I have a 3-1/2" gauge locomotive in our living room; on a bookcase, under a plexiglass top. If it was 7-1/4, it would be twice as long, twice as wide, twice as high, so would most certainly NOT be in our living room! Neither would the same model in 5" gauge - smaller than in 7-1/4, but still too big.

You have to decide what you want, nobody else can do that for you. Whatever you decide, it'll be the right decision.


Thread: Running coal fired 5 steam engine on gas
29/05/2018 16:48:57

Kevin - thanks for clarifying your reasons. Kozo Hiraoka uses his propane torch for testing/lighting up. Look at any of his books. (he uses coal for actual running)

Dave - for the burner I made for my Kozo Shay, it has a stainless arch which, according to the writeup, should be incandescent when running, so will help with the radiant heating of the firebox. As mentioned above, still have to test it, but it built to the "Raritan" plans, so is a published design.

Duncan - like you, I'd love someone (with your analytical abilities) to actually go through and figure this out. Many people seem to make it work, so there must be some definitive work "out there" that I have not found yet. Either that, or, it's actually simple, and hard to screw up!


29/05/2018 02:07:53

Hi Kevin;

By Gas, I'll presume you do not mean the American/Canadian "Gas" as a word for Petrol.

"Over here" propane firing is quite normal for steaming at many clubs. Some tracks (e.g. Train Mountain) you can't use coal due to fire hazards.

Now, the only direct experience on models is that I've built a propane burner for a 3-1/2" gauge locomotive from the "Raritan" design, but have not fired it up yet. (Bill Moorewood designed the locomotive and burner). Maybe now that the nice weather is here, I'll give it a try.

The Winnipeg group, the one and only time I was there, were all propane, from what I recall. I brought along my coal-fired Tich (3-1/2" gauge) and was thought to be a bit strange, I think!

I "cut my teeth" on full size steam on an oil-fired pacific, about the same size as your A4 (But, not nearly as fast!) Oil firing of full size was very popular on certain roads/areas, due to lack of coal, abundance of oil, and especially fire hazards.

Do some more digging - see what the Americans do, google for "Marty Burners", and see what you find. The information will be out there.

Thread: 049 glow plug RC aircraft?
21/05/2018 17:50:39

Hi all;

I was reading the firefly 46 engine build, and remembered the old Cox .049 glow plug engines; they were the rage with control-line enthusiasts back when I was a kid. I played around with one of these engines, but never tried flying a plane with one. looking on-line there are 3 of these engines for sale close by.

I saw that Cox engines and parts are still available, from someone in BC, Canada.

What's the general thought - are these still used on the RC fields, or is electric the way to go? I know it's not 1970 any more.

Thoughts? Thanks - John.

Thread: Emco F1 Mill Upgrade
14/05/2018 22:16:45
Posted by DrDave on 14/05/2018 18:24:09:

Thanks for the feedback on Linux. It is a couple of year since I tried to investigate LinuxCNC, so I cannot remember where I failed. I think that it was at the “mount the drive” stage. I will drag out my old Linux laptop & try again, just to have a play. But I must get the mill working first!

Don't worry - I'm behind in just about all of my projects ... Finished a short "couple of hours" project I started close to a decade ago last night - feels good! Now if I can only remember what I wanted it for! indecision

Thread: manual to cnc
14/05/2018 22:11:39
Posted by John Haine on 14/05/2018 19:35:12:

Just a thought - if you are converting a manual m/c tool to cnc, it might help to reduce the number of variables if you went for Mach 3, which has a wide user community?


This is my impressions of following this for a while.

I'd expect GRBL to have 10x to 100x the user community of Mach 3.

You can run it on those 3D printer boards, (it does not do extruders, unless it's been updated) so if you want a small CNC machine, it's ideal.

I gave away my Unimat CNC machine, and suggested that the user try GRBL for it, rather than go for high priced hardware, required for Mach 3 and LinuxCNC. (what's a 3D printer board worth? A pint of beer? less, if you get it from a defunct printer, I'd expect)


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