By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for John Olsen

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

Thread: Steam Canoe Machinery
09/08/2021 06:11:17

I don't know if you still have the larger boat, but if you do maybe you could come up with a trade through the Steam Boat Association. You would have a better chance of that in the UK than you would where I am anyway, here in NZ it would be unlikely for more than one steam launch to come up for sale in a year. Other than that, if you are a member, the whole run of the Funnel magazines is now available online, I have started to read the early ones and there is a bit about steam canoes in some of them. Another thing you could look up, some time back there was a steam punt described in the Model Engineer. He built a copper Yarrow style boiler for it which I think would be within the size that the Model clubs can certify. I'll see if I can find the reference, I would have all the magazines here in my collection.

Steam launch props do tend to be on the large side, with large pitch too. The large diameter is good because a large slow turning prop is more efficient, and the high pitch is necessary because of the relatively low RPM. For an example, the prop on my "Dancer" is 22 inches pitch and 22 inches in diameter. Enormous compared to what you would see on say a 120 hp outboard. I don't have any measurement of the power that the steam plant puts out, but from back of the envelope calculations it is not going to be over 10 bhp on the shaft and probably less, yet that is enough to drive Dancer along at a good 8 knots.

I think I said this already, but anyway, I would avoid the Stuart Number 1, although it is a fine engine. I have built two of them, one with reversing gear. Although they are nice, they are not really beefy enough for the continuous work in a boat. You can sneak in bigger bearings if you try, by making a new crankshaft as large as the space will allow, but the crosshead is still single sided, and the bored type like on the 5A is preferable. Some guys here in NZ made a set of castings for an engine very like the 5A, but with ball bearing mains and I think for the big end too. This makes a very sound job and they have been quite successful in a couple of boats here.

One thing that Cliff Blackestaff said in those early Funnel magazines that I think is worth repeating, don't go for a typical vertical firetube boiler, it puts too much weight up high for a canoe style hull. (The low squat type is OK) You either want a horizontal firetube (Scotch or similar) or a water tube boiler. It used to be that any weight saved with a small water tube boiler was lost in the weight of the insulation for the casing, but now that you can get ceramic fiber based insulation I think you can definitely save some weight with the water tube type. This could be helpful with a canoe. The other aspect is that a tall vertical boiler can look a bit silly in a small boat.



Thread: Triple Expansion Engine
08/08/2021 01:03:40

I have all those issues. Looks a nice engine, might be a bit fiddly to build but a good size if you ever want to put it in a model boat. (The Stuart is a bit big for a boat, unless you want one about 6 feet long)

I'll send you a PM.



Thread: Hydrogen
23/07/2021 02:44:59

Yes, Lithium is not really a problem. There was concern about things like cobalt being needed for some of the Lithium battery types, but I think the need for that has been reduced or eliminated now.

I don't think Lithium is actually a rare earth anyway, at least not on my copy of the periodic table. Where the rare earths come in is for permanent magnets which may be in the electric motors, but then, they don't have to be used there either. Electric cars can use ordinary off the shelf AC induction motors, and I have driven one that did.

Funny thing about mining, once it has stopped it is romantic and a great tourist attraction.


23/07/2021 00:17:02

The reason I asked above about the hydrogen mines is because of course there aren't any. All hydrogen has to be manufactured, at present mostly from fossil fuel stocks, in the process releasing lots of carbon dioxide into the atmosphere, a thing we were supposed to be trying to avoid. The Germans used to use a different process of passing steam over red hot iron, the iron of course having been made by the usual process involving coal and lots of carbon dioxide.

The point is that hydrogen is not a source of energy, it is merely another way of storing energy and transporting it from place to place. The question them becomes is it a good and economical one? Hydrogen is tricky stuff, it is a small molecule and loves to escape out of containers, through the pores of the metal if necessary. It also ignites quite easily. It takes a lot of energy to make the hydrogen, so the electricity generating system will need upgrading whatever you do.

If you are going to burn the hydrogen in an IC engine, you need to consider that the efficiency will be quite low, so you will probably need to carry more fuel. For this technique you would probably be better to synthesise hydrocarbon fuels, using water and CO2 extracted from the atmosphere. The resulting fuel can then be distributed using the same networks as at present. Since the C02 is extracted from the atmosphere, the process is carbon neutral, and the only major technology change is at the refinery and the power plant providing it with the energy needed for the synthesis. But the overall efficiency remains low since IC engines are pretty abysmal at best.

If you decide to use hydrogen fuel cells, the efficiency will be much higher, since from what I hear the fuel cell can be up around 90% or so, and the electric motor that it runs can also be pretty high, much better overall than the IC option. But the fuel cell currently requires pure hydrogen although I believe there is work being done on cells that can accept hydrocarbons. So you tend to need a new fuel distribution system. The other thing to consider is that the cells tend to require rare and expensive catalysts inside, more so than batteries. It seems that it is possible to eliminate the rare metals from Lithium batteries, it is going to be much harder to eliminate the catalysts from fuel cells.

So long term I don't know what the best solution will turn out to be, but hydrogen is not a panacea. In the meantime, if a battery electric suits your needs then you should probably consider one...they are not suitable for every use case, but if everyone who could use one had one it would make a difference.


22/07/2021 06:57:53

Where are the hydrogen mines?

Thread: Digital CNC phase converter build
20/07/2021 12:12:48

OK, I was thinking in terms of the usual model engineering scale of things, where a Bridgeport is a big machine, you seem to be looking at quite a bit more power than that.

The two phases of your existing supply being at 180 degrees doesn't actually matter, you just need a third phase at about the right phase angle and voltage and things will work. I stand to be corrected here, but if you had a star connected motor, I think the centre tap of the transformer would not be an actual neutral point and so should not be connected to the star point of any motor. Think about it like this, if you had a 480V three phase supply and measured the Voltage between two phases and looked at it on a scope, it would look just like what you see with the single phase supply. So it is true that your converter just needs to provide one new phase at 90 degrees. (We could do vector diagrams to show this....) But this will be effectively a delta connected supply, with no actual neutral point. If you want one you can provide a delta to start transformer at the output although for 40 hp, say 30 KW or so that would be a big and expensive transformer

If there is a rotary component, eg an idler motor, then what you get out will be not too bad. I've actually run a 3 HP 460 Volt motor on single phase, with the 240 Volt supply being stepped up by a transformer and applied to two of the motor connections. It did not self start of course, but a kick on the pulley in the right direction would get things going. I never measure it, but had I needed to run another three phase motor, connecting it to the three phases of that motor would have provided a converter.

With electronics of course it is possible to do this sort of conversion at any sort of power level you like, so long as your wallet can stand the pace. AC to DC and back again is pretty standard for long distance and undersea transmission, and they work up into the 100's of Megawatt range. But I don't know what is commercially available in the sort of size range you want. It won't be cheap, but then the transformer and idler motor won't be either.

Hopefully it is redundant to say that any system will need to be done properly and in accordance with any local regulations, this sort of stuff can easily kill you or burn your house down!



20/07/2021 01:36:40

First consideration has to be how much three phase power do you need? Closely allied to that is the question of what can the existing single phase connection provide?

After that, I guess you will have to look at the cost and merits of the different approaches.

1 A static converter (Transformer plus inductors and capacitors) will work and allow you to use more than one machine from it, but the phase to phase angles will not be ideal .

2 A rotary converter, similar to the above plus an idler motor will give better output phases but will waste a bit of power keeping the idler motor turning. The idler motor provides a bit of flywheel effect, helping with the surge when you turn a machine on.

3 The various sorts of electronic inverter will provide excellent output waveforms and so on, but may cost a little more. You have the choice of providing one big one that all the machines connect to as if it was an ordinary three phase supply, or little ones on the basis of one per machine, which give the advantage that you can use the inverter as a variable frequency drive.

4 Generate your own three phase as per Noels suggestion. Perfectly feasible but has its own set of troubles like noise and complexity.

5 Pay through the nose to have three phase installed. This always seems to cost far more than the job really warrants, I get the impression that suppliers around the world would rather you didn't have three phase.

You can't add capacitors to the AC output of an inverter to smooth the supply or to provide for starting surges. On electronic inverters, such capacitors would go inside on the DC bus and you would not want to try to modify the design. There will be small capacitors on the output to help suppress interference, and you probably don't want to change those either. On a rotary inverter, the idler motor provides a flywheel function.

My own preference is to use a VFD for each machine, which gives the advantage of variable speed, but for some machines this means getting inside to alter the wiring, eg to make sure that a coolant pump or a fine feed motor is getting what it needs rather than running off the variable frequency supply. Some may not be comfortable modifying their machines in this way. I think with the relatively low cost of VFD's these days it is quite a good way to go.


Thread: re-magnetising magnetic base
08/07/2021 04:23:09

If I needed to do something like that I would be thinking about using my DC inverter welder to provide the necessary current. It can do 200 Amps, and has its own built in current limiting so it is not going to complain if it is connected to a coil of heavy wire. Then it would be just a matter of making up a magnetic circuit with the coil of heavy wire around it. It doesn't actually take very long to remagnetise things, long enough for the field to build up to the maximum, which is going to be in milliseconds rather than seconds.

Another approach is to use a car battery and a coil.


Thread: De-snagging an SL125
27/06/2021 04:45:24

I had the CB100, rather than the SL version, but the muffler was just a large chamber, the only baffle it had was the little unit that appears as part 6 in your picture. It was not excessively loud, even after I converted it to 125 and put a hot cam in it. They never had any packing material like the Dunstall Decibels used. (I had one of those on a Triumph 250, it was reasonably quiet just after it was repacked, and got louder quite quickly as it shredded the packing and blew it out the back.)

I did notice when I had occasion to ask some years back that Honda mufflers were a bit on the pricey side. Bad enough if you just want one, but it would help explain why the fours after a couple of years all had four into one systems fitted. Quieter, lighter, and cheaper as well as more power!


21/06/2021 03:09:14

The shaper compares more to a horizontal mill than a vertical mill in terms of the work it does. Great for flat surfaces, not so good at making pockets and boring holes. You can do some interesting things if you put either a rotary table or a dividing head and tailstock onto a shaper.

However, in terms of the sort of work mentioned, eg small stationary engines and locomotives, my suggested order of acquisition would be the lathe first (of course!) followed by a vertical mill. The mill will also act as a drill. Shapers are not available new, so if you decide you want one, the best course is just to keep your eyes open and see what comes up. On the other hand, if you were able to get a mill that does both vertical and horizontal milling you probably don't need a shaper. Still, I like having mine, and I have three of them.


Thread: Steam operated drain cocks
14/06/2021 05:01:57

Sorry Duncan, 1 is the end that should connect to the cylinder. The pressure from the steam on the other end holds the valve on the seat. When there is no pressure there, any pressure in the cylinder can open the valve, allowing it to drain. The ones on my steam launch are just like the one shown, and they work fine. If the pressure in the cylinder gets high enough, say from trying to compress water, it can overcome the steam pressure on the other end and vent anyway, so they act as a relief valve, although I have also provided separate relief valves as well. The operating valve should be a changeover type, so that in one position it connects live steam to the valve, and in the other it connects the cylinder end of the valve to atmosphere.

The operating cylinder part needs to be big enough to hold the valve on its seat, but not so much bigger that it won't act as a relief valve. The ratio of the areas will approximately determine the pressure at which it opens.

I don't have drawings of mine, they were made by eye from a sketch, and they would be a bit big for all but the largest of model locos.


Thread: Dividing head - Beval gear ?
09/06/2021 11:09:19

You might find a bevel gear on the outside if it is a differential dividing head, but the gears on the inside will normally be a worm and pinion. The number of teeth on the pinion would tell you the ratio of the head, it is unlikely to be a multi-start worm. The worm would have to have a tooth form and pitch to match the pinion. Could be made, but is it going to be worth the trouble?


Thread: My Starrett clamp can cause cancer....
09/06/2021 11:03:03

It is a CYA thing, you can get in trouble in California by not putting the label on, but you don't get in trouble by putting it on when it is not needed. So the natural result is that firms play it safe by putting it on practically anything.


Thread: Stuart 10v valve rod
09/06/2021 10:58:54

From what I recall of the 10V and Double 10 that I have built, the main length of the valve rod should not need turning down. Only the short length on the end that goes into the guide hole in the end of the steam chest. If the rod is only a little oversize I would look at making the holes to suit. If it is much too big, order some the right size.

If you do have to turn down a long slender piece, there is a way of doing it with a combined steady and cutting tool. This needs a piece of steel held in the tool post, with a hole drilled in it on centre height that matches the starting size of the rod. A piece of tool steel is then attached on the right hand side that takes off the desired cut. The hole guides the rod so it can't deflect. A bit fiddly to set up, and possibly too much trouble unless you have a lot of work to do.

The moving out from the chuck idea works better if you have a collet chuck.


Thread: Steam Canoe Machinery
05/06/2021 08:48:22

It seems to me that your biggest hurdle is the lack of equipment to build your own plant. Buying a suitable boiler an engine as bespoke items will be very expensive. A lot of money would be saved by buying whatever comes up as second hand or estate items, but that way you won't always get exactly what you want.

There is quite a lot to be said for just making a start in the direction you want to go. Once you have started to make some progress, you might be surprised what shows up. With my own project, I knew when I started that my machine tools were not big enough, so I started on what I could do with what I had. When people see that you have made a good start, they will be much more likely to offer you access to their machines, whereas if you ask before they have seen what you can do they are likely to be much more cautious.

In your case, it would seem to make good sense to start with the hull, since it seems you have suitable facilities for that. At a pinch, a small hull like this can be built with just hand tools, although sanding is something where I would regard power tools as essential. At worst, if you have a finished hull and no plant, you can paddle it, row it, hang a little outboard or trolling motor on the back, and so on.

Don't forget to allow for all the ancillaries. You need space to build it and later store it, you also need some way to get it to the water. Storing it at or on the water is a lot more expensive than storing it at home, where you can also conveniently work on it. Larger boats like mine are of course more of a problem, and actually between buying a substantial boat trailer and a four wheel drive to tow it, and an 84 square metre shed in the back garden to store it and work on it, there is far more money in all of that than there is in the boat itself.

So anyway, there is no substitute for making a start.


Thread: Window on the World?
05/06/2021 08:15:58

There are probably others more familiar than me with this type of setup, however, here goes. I think usually the way of turning off a magneto is by switching a short across the points. There is of course no battery power going into a mag, so you can't turn that off. On the other hand, the light switch is usually arranged to switch battery power to a bulb. So there will be one connection to the battery live side, and as many output connections as it has functions, eg one for headlight, one for sidelight and so on. So the switch is intended to switch power to a load, while the magneto needs a connection made to ground for off.

So if the switch is being used to switch lights, it probably cannot directly be used to control the magneto as well, however it can be done indirectly. Suppose you want the "side" to turn the ignition on. You provide a relay with a suitable coil, 6V or 12 Volt depending on the battery. You connect a normally closed contact set across the magneto points. When the switch is in the on position, the relay pulls in, the contacts open, and the magneto operates as normal, When the switch is off, the relay drops out, the contacts close, and the sparks stop happening. If it is on a motorcycle, you want a good robust relay as vibration is not good for this sort of thing.

If the switch is not also being used to control anything else, you could also use just the switch on its own, however the "on " position would short the points, stopping things, and the "off" position would allow the engine to run. You wouldn't need a battery for that setup.


Thread: Unimat sl with high tailstock
03/06/2021 08:50:10

Just to add to the confusion, there is also the Unimat 3 with the more conventional style bed, a V section at the front and a flat at the back. The DB/SL is the earlier type with a pair of round bars for the bed. If I recall correctly, that one could have the headstock easily swivelled to allow taper turning, and also the headstock could be taken right off to go on a milling attachment. So this would imply that a shim could easily be added to that end. It does sound like the tailstock and headstock may come from different batches or something like that.


Thread: Steam Canoe Machinery
29/05/2021 23:14:13

While I would agree that the No 1 is about the right size, it has the single sided crosshead guide. This is not as robust as the bored crosshead design on the No. 5. Also the main and big end journals are bit on the small side for continuous work. This applies to the 5 to some extent too. I would suggest making a new crankshaft with the maximum diameter that the brasses can be made to accommodate.

The prop size is compromise, you want it large and slow turning for efficiency and small to permit low draft. Can't have your cake and eat it too!

Electric transmission makes sense when we have to match an engine to a highly variable load, but we already have a prop, which acts a bit like a torque converter, and a steam engine is also very flexible, so we don't need it.


28/05/2021 22:50:18

From what I have seen, your 1.6" bore would probably be enough. Having said that, if it was me I would probably go for a 2" bore and stroke. You can notch it up to improve cruising economy. You won't need a lot of power, the Leak compound in Dancer (thirty feet long, 2.4 tonnes) is maybe capable of 10 bhp at best, and that will drive her to about 8 knots.

Calculations of hull speed are highly empirical, the maximum for any given hull will depend on the hull form and total displacement as well as the length. A canoe shaped hull is likely to have a slightly higher speed than a bluffer shape.

Most of the Stuart engines are designed more for a scale appearance than for hard work. Increasing the journal sizes would be worthwhile for boat use. The 5A would be a good choice.


Thread: Clarke Tig Welding Gas Bottle/Regulator
16/05/2021 04:20:14

Here in NZ, both from the same supplier, I can get either a disposable bottle with 242 litres of gas for NZ$98, or a refill of 1000 litres on a refillable bottle for NZ$80. Obviously UK prices are likely to differ, but I suspect the savings will be of the same order, eg 4 times as much gas for much the same price.With the deal here, you do have to buy the bottle, which is then swapped every time you need to fill it. This does mean that you don't have to worry about testing the bottle eventually. The refillable bottle, which comes full, costs NZ$300, which means that it is cheaper than the disposable even if you bought a new one each time, eg the gas equal to 4 disposables for the price of three. But then when you swap it, you get the equivalent of four disposables for less than the price of one.

I did start out with a disposable bottle, the only good thing about that is that once it was empty I was able to weld on some feet, ears, tail, and snout to turn it into a piggy bank.

The only time the disposable would make good sense is when you need to cart the gear into some awkward to reach place, a long way from your vehicle or up a tower. With a small inverter welder you could have quite a portable kit. Of course that place would need power available too.

As to the original problem, I suspect that the bit on the regulator is not poking in far enough to open the valve on the bottle. If that is the case it should be possible to get a refund on the grounds of not fit for purpose.


Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Latest Forum Posts
Support Our Partners
Eccentric July 5 2018
Rapid RC
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest