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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: Miniature Magnetos
24/06/2022 23:09:57

The way I am doing it with the Red Wing is that the magneto mounts inside the base, so is out of sight. There are two extra gears to drive it, but being inside the flywheel and below the cam assembly they are not conspicuous. This is not original to me, there is a video on YouTube somewhere by the guy who came up with the idea. The Vietti one seems like a nice arrangement.


24/06/2022 00:47:13

I bought a Minimag short form kit (FMK) in 2019. At the time they were not in stock, and the comment from them was that they had stopped making them due to lack of demand, but that perhaps they should not have. Anyway, at the time they managed to source some of the necessary components and put together one for me, and I think possibly a few others. So it would be worth contacting them to see what they can do.

I had some fun getting mine timed up properly to get a decent spark, the breakthrough was when I bought an oscilloscope, (not just for this job) which enabled me to see the voltage across the points and so get the timing set accurately. I haven't actually run the engine yet, there are some fiddly bits on the carby that are giving me trouble, but I am confident that the spark will be OK. The Minimag kit is not too much of a challenge from the machining point of view, the timing is a bit tricky since the cam is inside and only accessible though a small hole. The engine is a PM research Red Wing.



Thread: De-snagging an SL125
20/06/2022 22:32:55

I recently acquired most of a 1978 XL125 from the scrappy. Missing the back wheel, the petrol tank, and the gear and kickstart levers. Pretty much the same bike as the OP's SL125, except this one has the two piece head, It also has a bit much play in the camshaft bearing, so I might have to build that up with a bit of TIG. Not the only work it will need, but having owned a CB100 back in the day I couldn't resist rescuing this one. The CB100 was also the same engine, apart from the bore. The experience back in the day was that the 100 was just as quick as the 125, mine was even quicker once it got a hot cam, a bigger carb, and a 125 barrel.


Thread: Cylinder drain cocks
15/06/2022 15:51:51

I was going to say that I would probably try to file them, but Roy has beaten me to it.


Thread: Emco Compact 5 - complete newbie
13/06/2022 05:37:28

I don't know whether or not the original Emco table is still available, but if it is not, then one approach would just be to get hold of a piece of aluminium plate maybe 10 to 12 mm thick. Drill holes and counterbore for the holding down screws, and drill and tap holes as needed to hold jobs down. When it gets too many holes, make a new one.

The original chucks i think don't actually use separate backing plates. They can be made if you want to fit other chucks. I may be awry here, my own one is a Unimat which has the screw on chucks. The backing plate for the Emco 5 chucks might be easier to make since it does not need screwcutting.

The original Unimat collett chuck came with a backing plate and the chuck register side was a little oversize, you turned it down to fit the register on the chuck body which in theory gives a perfectly accurate chuck. They probably did the same thing for the Compact 5 and again, the backing plate would not be an impossibly hard task for a learning exercise. It is very handy to have a collett chuck for the lathe since it will hold round stock true. Also vital for the milling attachment for holding milling cutters.

I think the chuck attaching screws will be allan screws, eg with an internal hexagon drive. They are used elsewhere on the machine, and so it would be worthwhile picking up a small stock in a variety of lengths. They also come in handy with the milling table. They will be M6 as far as I know. If you do get hold of an original milling table you will want some T nuts to suit and that would be a good beginners project.



Thread: Telephone Ringback Code?
13/06/2022 02:11:30

While we are on naughty things to do with phones... There were a couple of techniques with the old coin phones. One that required a bit of skill was dialing the number you wanted by flashing the switch hook. That required some skill, and the techs in the exchange could often hear that it was being done, and would drop the call for you. Another was to put the money in as per normal, but instead of pushing the button when the called party picked up, you just talked very loudly into the earpiece. This worked well enough as a microphone to let you talk to the other person. Then when you had finished, you pushed button B to get your money back. I tried this as a lad to prove that it worked, but never made serious use of it.

Later when I was working for the NZ Post office, there was a trunk between most of the PABX's around the district. They weren't all that well documented, but of course idle fingers tried all sorts of likely numbers just to see where they went. To find out, you would dial a likely code and then 0 for the operator. When she (which it generally was back then) answered you would ask where she was. This tended to confuse them a bit, but in this way we managed to document quite a lot of the system. Once we had a good idea of the setup, we could dial a call into and out of lots of the local PABX's, then back to another phone on our one. That would ring OK, but having been through so many PABX's. the voice was often too weak to hear. (PABX...private automatic branch exchange, like the ones larger businesses have.)

The in the eighties the office I was working in was equipped with one of the new PABX's with all sorts of fancy features. Like "ring me back when the guy I want to call hangs up" and "Ring me back when he is there". So one lunchtime, I had a lot of fun after everyone else had gone setting up a whole string of the latter from a number of phones. The way it worked was if nobody answered, you put in the code for "ring me back" and later, when someone used the phone and then hung up, the exchange would first ring your phone, then when you picked up, would ring the party you had been trying to call. All very clever, but when you set up a whole lot of these between a whole lot of phones it becomes a bit of a minefield. You just have to be careful when setting up that you don't pick up any phone that you have already set one up to, but you can set up a whole lot of them. Anyway, having committed this act of sabotage I went off to lunch myself. Luckily the boss was not the first back! The guy who was would have had no problems until either he made a call from one of the phones, or someone from outside called in. After that call was finished an he hung up, a number of phones would have started ringing. Being diligent, he would have rushed over to answer the phone, only to have another phone start to ring...Anyway, he told me that if I ever did that again he would personally kill me.


Thread: Target for This Month: A 3D Printed Engine
09/06/2022 22:44:32

NSU made a motorcycle years back that had the cam driven by connecting rods. but of course there were two of them with the cranks at right angles. Since it was a four stroke, there still had to be a two to one reduction gear.


Thread: Question for moderators, please
08/06/2022 22:49:49

An entire thread about changing belts on the ML7 has also disappeared.

Thread: fixing loose valve guide
27/05/2022 05:28:48

Is bronze a suitable material? Some of the bronzes go hot short and will collapse a little and come loose in the head. Phil Irving says in his book that aluminium bronze for instance is not suitable for exhaust valve guides, which is probably why BSA/Triumph used it on my 1971 Blazer SS 250 single. It was failed when I got the bike(which I knew) with about 1200 miles on the clock. It got replaced with a cast iron guide, shrunk in with the head heated as hot as we dared and the guide cooled down with spray on freeze. Never gave me any more trouble.

Funny thing was later, when I was talking to a guy who specialised in fancy cars like Ferraris etc, he said "cast iron is fine for guides but it can hang up at high revs" To which I replied "That's OK, this engine only does 8500rpm." He got a funny look on his face, so then I said "Well, my little Honda has cast iron guides and that is redlined at 11000..."


Thread: Swedish Iron
21/04/2022 11:12:07

The iron has its magnetic properties at ordinary temperatures. Where the high temperature bit comes in is that any iron will lose its magnetic properties at a high temperature. With soft iron like this, the permeability will drop at a high temperature, but it will regain it when cooled. With hard irons like permanent magnets, they will become demagnetised at a high temperature, and will remain demagnetised when they cool. The temperature this happens at is called the Curie temperature, and is the same temperature you want to attain for hardening things like silver steel, eg Cherry red, or more usefully, about the colour of a boiled carrot. This all happens because this is the temperature at which all the crystalline structure gets disrupted by the heat. It is not really a difficult temperature to reach, a propane torch will do it nicely.


Thread: Steam Canoe Machinery
30/03/2022 23:51:36

To take the last point first, you probably should think about condensing, if not as part of the initial installation, at least as something you will want to add. Otherwise you have to plan on carrying as much water as you might need, or else on filling up from over the side with water of possibly dubious quality. A keel condenser is probably the simplest way to go. A surface condenser will require a circulating pump, eg another thing to go wrong. My plant actually has a surface condenser, luckily I was able to find a nice gear pump for the circulating pump which has the merits of being very simple, no valves, very quiet and absorbs very little power. But there is still much to be said for the keel condenser, the main downside being the prospect of damaging it while grounding or trailering the boat.

Sizing water pumps is not necessarily all that easy, I followed the drawings and found that in practice I needed to increase the size of the pump rams. As it stands now, I can keep the boiler at a steady level with just one pump running. The Weir pump might have been someone being cautious, it is nice to have plenty of backup to get water in the boiler if you have a coal fire. Not so bad with my oil fired setup, where at the flick of a switch I can take the heat away, if the water level got too low.

It's not Stuart that had the engine speed pumps, my Leak does although as mentioned above, they are scheduled to go as soon as I figure out how to fit things in. Some other designs do to.

One feature of the Cygnet design that I would question is the location of the air pumps, high up. This suggests that they are going to have to lift the condensate from the condenser in most cases, where people use a keel condenser. If you are lifting the condensate through a foot, you are losing an inch of vacuum. So keep the pump low, close to the condenser.

The tendency towards the end of the original steam launch era was to go to shorter strokes and higher rpm. This has the merit of reducing the required prop size, allowing it to fit into a smaller cutout in the hull, and also reducing the required draft. The engine becomes more compact too. A smaller prop at higher speed has lower efficiency, so it is all a bit of a tradeoff.


Thread: Gasless MIG welding
30/03/2022 07:15:59

My vote for us amateurs would be to always get the most capable setup you can. Not to get fancy features that you may never use, but to get really helpful ones that make things easier. As an example, when I was first looking into TIG so I could do stainless steel tanks, I was tempted by the lower cost lift start, but then was shown a much more capable machine with RF start, and a few other features like pulse. It is not a top of the line machine, but quite good enough for a single phase machine. The RF start is much easier for a learner than lift start, the later being a good way of contaminating your tungsten unless you have the knack of it. It also came with features like AC. I didn't know when I was first looking just how useful the ability to weld aluminium was going to be. The main nice to have that it lacks is the ability to vary the frequency when AC welding. Since it is an inverter, I don't know why they didn't include that, but so far it has not mattered.

Of course the above is not very relevant to the choice of MIG machine, since my machine does not do that. If I was going to get a MIG machine, my inclination would be to get one that does use gas, get the hang of things with that first, then try the gasless when I felt I had the need for it. This is because I have a feeling that the learning curve might go better that way, but since I don't do MIG, only MMA and TIG, I am ready to be corrected if anyone knows better. Incidently, DC MMA welding has done a lot to improve my basic stick welding too, every time over the years that I have upgraded my equipment for MMA my welding has mysteriously improved.


Thread: Murad Cadet Restoration Project
30/03/2022 07:00:24

If you are going to change the motor anyway, put on a three phase with a VFD. Well worth any extra cost.


Thread: Steam Canoe Machinery
29/03/2022 22:23:51

There would normally be two boiler feed pumps, and if the engine is to be condensing, one *vacuum pump. The two water pumps gives you a backup if one fails, and also allows bringing up the level a bit faster if you use both at once. There is no law against having more than one vacuum pump, so maybe that is what they did. It has to have sufficient capacity to remove all the air and condensate from the system, and maybe if they were using a commercial item one wasn't quite enough.

* No doubt someone will get all pedantic on me, some people don't like calling it a vacuum pump, claiming that the vacuum is created by the condensation of the steam into water. Actually there would never be a vacuum in the condenser if the pump didn't pump all the air and condensate out, and vacuum pump is less of a mouthful to say than air and water pump. Of course it is never a true vacuum, but then nothing ever is, not even in deep space.


26/03/2022 10:27:12

Are the Stuart pumps driven directly off the crosshead, eg at engine speed? If they are, I would suggest not using that design. The best pump arrangements I have seen on small steam boats use a reduction drive to drive the pumps at about 1/3 to 1/4 engine speed. The merit of this is that engine speed pumps are very noisy. Reduction drives can be toothed belt or gear, the toothed belt is quieter but may offend the purists. (So hide it in a casing.) Actually a worm drive would also be possible, the feed pump for the model Stuart double 10 uses one.

Dancer has lever operated engine speed pumps as per the original Leak design, once I figure out how to fit a reduced speed setup into the extremely limited space available they are going to be replaced. The original arrangement might be more true to full size design, but engine speed pumps are VERY NOISY! Sorry about shouting but you probably would not be able to hear me over the noise of those ******* pumps.

It is a bit of a problem, most of us like the idea of a slow turning engine with gleaming parts that you can see going around, but the reality of getting power from small engines is that they need to turn quite fast. Reciprocating pumps, on the other hand, do not like being driven fast.

But on the other hand, the engine you have acquired looks like just the thing.


Thread: Myford Lever Action Tailstock Design and Build
15/03/2022 02:14:29

I have the exact same 4 inch micrometer here, picked up at a club auction more than 20 years ago. A really useful bit of kit. It is complete with all the little spanners and calibration pieces too.

I've just come inside from a similar piece of work on the lathe, but the hole I needed was 75mm in a funny triangular shaped piece of inch thick alloy. I had to reverse rwo jaws of the four jaw chuck to get it into the Myford.

My Myford has a lever action tailstock, made by my late father using a rack and pinion out of a small car.



Thread: Myford ML7 1956 ... Question on drive belt and Stalling when cutting
06/03/2022 19:08:07

I found that the standard V belt was heating up the spindle pulley, to the point that the bush inside would come loose. Apart from securing the bush better with loctite, I made a new set of pulleys for it that use a poly V belt, which does not heat the pulleys. As a bonus, I was able to squeeze in an extra step and widen the range of ratios slightly, because poly V will drive satisfactorily around a smaller diameter. Hemingway does a set for using Poly V on the Super 7, but not for the ML7.


Thread: Shaper tooling.
02/03/2022 05:09:56

There is a photo in my album of a selection of shaper tooling and I have just added one more of a J&S zero rake toolholder, good for shapers and also for brass in a lathe, you can more easily grind on a bit of negative rake for brass if the toolholder doesn't have lots of built in positive rake. From the first photo, car keys for scale only...The left hand tool is a home made brazed carbide tool, I find these work fine in a shaper. Then three old style gooseneck tools, also used on lathes back in the day before I was born. Not really needed if everything is nice and rigid. Then two of the type under discussion, both by J&S. The large one is actually too big for any of my shapers, but maybe one day I'll find something big enough. (It would need to be at least a 24" machine...)

The last photo is a J&S zero rake holder, it would be nice in my 18" machine but is just a little too wide for the lantern toolpost and I don't like to modify either of them


Shaper tooling


01/03/2022 20:00:49

That type of toolholder is useful, with a few caveats. They will only work with fairly long pieces of tool steel, and will unfortunately quite easily turn longer pieces into a selection of short pieces if things turn to custard. The end is fairly bulky so can get in the way a bit, and this tends to cause using them with too much overhang.

There is another type of toolholder intended for shapers, it is just like the ones meant for lathes, but without the built in top rake. Because the end is slimmer it does not get in the way so much.

You can actually use the lathe type, but they are not ideal since they put the cutting edge out in front of the pivot. While this is not good from the point of view of digins and chatter, it can work, and the dovetails on my dovetail mystery, published in ME more years back than I care to remember were done this way.

Art Volz was very active on the old Yahoo shaper group, and was kind enough to send me some drawings of the authentic vice for my 6 inch Ammco. I had castings made, I really should finish machining them sometime soon!


Thread: Frank Boler 10cc 4-cylinder 2-stroke engine
22/02/2022 01:29:21

Yes, what I have in mind is that you might be able to find enough information to allow you to design an engine like the Frank Boler one, if not exactly the same.



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