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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: Ford Quadricycle Engine
11/01/2021 23:40:06

The Model T is in fact a prime example of early ignition weirdness since it used both DC and AC. There was a battery box with dry cells, used to provide the spark when starting. (But not cranking, which was manual) Because of the trembler system, it was not impossible for the engine to start immediately when the ignition was turned on. This required a fluky situation, a cylinder that happened to be full of mixture from the last run and stopped in just the right position so that when the ignition was turned on, the resulting spark kicked the engine over. I have heard that this could be so startling that the result was that the ignition was immediately turned off again.

The other aspect of the vintage vehicles is that they often are valued greatly because they are rare, and often the rarity is because they were no good in the first place. "There were only five ever made and this is the last one in existence." This does not of course apply to vehicles that were never intended to be made in quantity, like racing cars and ultra luxury vehicles.

The CDI system I was thinking of is commonly sold for model aircraft applications, it is not much bigger than a box of matches, including the coil inside, and would easily conceal inside a quarter size seat I should think. It will run for a long time from a small battery pack. It uses a small magnet and a hall effect sensor for timing, also easily concealed.


11/01/2021 20:33:07

PM research sell a trembler coil for use with their Red Wing engine. It may be available from some of the UK sellers of their castings, some of whom I think may advertise on this site, or in the magazine at least. The Model T Ford used the trembler coil system. I'm not sure what the quadricycle used even though I have seen both of them. If I recall correctly, there are two of them, the original one in the Ford museum and a replica in the replica brick shed in Greenfields village.

Early infernal combustion engines used all manner of weird ignition systems, some with moving contacts inside the cylinder, which never seemed like a good idea to me.

One idea would be to use a modern cdi system, hidden somewhere. Not authentic but very effective.


Thread: Interesting shaper-Newey
11/01/2021 02:50:41

It looks quite a lot like the larger Alba shapers, eg the 14 and 18 inch ones, both of which I have owned. (Only got the 18 inch one now.) My 18 inch one was missing the table support too, so I made the castings for each end.

Compared to what I have paid for my ones over the years, that looks a bit spendy to me. My 18 inch was NZ$350, which might be somewhere between 100 and 150 British pounds, with a very substantial vice. Usually the smaller machines (6 to 10 inch) are worth more, easier to fit into the shed.


Thread: TIG is harder than it looks
03/01/2021 05:48:36

I am no expert, just an amateur at all forms of welding, so for what it is worth here is what I have learned in a year or so of playing around...

1 Cleanliness is everything. Especially with aluminium. Stainless is not so hard since it tends to be cleaner. Clean the filler rod too.

2 Remember to turn the gas on! Seems obvious enough but I have forgotten at least twice. If you do forget, clean the job again. (Use the right gas too, not the mixture intended for MIG. I haven't done that, but I gather it is not a good idea.)

3 If you touch the tungsten on the job, stop. Regrind the tungsten and clean the job again. It will not get any better if you try to keep on going.

4 If you are making stainless tanks, like I was on my first major job, do not flange the joints. A nicely fitted butting corner is much easier to weld and often does not even need filler.

5 Aluminium is harder to TIG, get some practice before trying anything critical with it. If it starts to get out of hand, stop and let it cool for a bit. Some of my best joints have that "stack of dimes" look, many don't!

6 Buy a reasonably capable machine, Having HF start in particular is good, scratch start is for experts, not learners. Arc force is good on MMA, but not needed for TIG. All those settings might look a bit daunting, but better to have them and not need them than vice versa.

I mostly don't use TIG for welding mild steel, I use the same machine but on the DC stick setting. I find that the welds I can do that way are so much nicer than what I used to get with an old AC arc machine that it is not worth expending the argon to try to do better with TIG.

I have a foot pedal, but I am not multidextrous enough to get much value out of it yet. The machine also does pulse, but I haven't made a lot of use of that yet either. I have welded stainless, aluminium , and copper, the latter being inch size plumbing tubing, quite thin in the wall. It didn't come out very tidy but it holds vacuum in OK.

Welding is a trade in its own right, as an amateur I do not expect to ever get to the level of the professionals, but with practice it is possible to do a reasonable job .


Thread: Improved performance over standard V belts?
02/01/2021 03:30:05

I converted my ML7 to use poly V belts, the flat licorice strap type now common on cars. They are a great improvement, they don't get themselves or the pulleys as hot as the V belts. Hemingways do a kit of converting the Super 7, but that is not applicable to my machine. It is critical for the pulleys to align properly, one of my steps is slightly out and the belt will try to work sideways on that step. But that is not too important, I actually gave mine four steps so between those and the back gear and the VFD I have plenty of speed range to choose from.


Thread: Vertex Dividing-Head - basic help please
02/01/2021 03:24:51

The other lever on the side is as you thought the spindle lock.

The bronze piece with the curved slots is how you would adjust the backlash and take the worm out of engagement. For direct indexing I find it easier to leave the worm in engagement, and just wind the handle until the pin will engage in the hole.

I think the part about indirect indexing is just telling you to get the worm engaged with the worm wheel, you would do this before putting on the dividing plate. The main thing is to have the worm engaged well enough to not have too much backlash, but not so tight that it starts to bind. The two screws in the curved slots should be allan screws, and should not need to be done up excessively tight.

They tend not to come with T slot tenons since they have to fit the particular milling table, which may not have T slots the same width.

I have the original Vertex instructions for mine. I could dig them out and scan them. Mine is of about eighties vintage and does not take Myford chucks, more's the pity, although screw on chucks are not ideal for milling. I was lucky enough to acquire a spare three jaw which now fits it, and I also have a faceplate for it. The taper is a Brown and Sharp, also a bit obscure. With any luck, yours might be a Morse taper.


Thread: Difficulty Operating Solenoids with an Arduino Uno
31/12/2020 03:49:46

The best feature of the AVO is that you can stand on it to change a light bulb.

Even when I was using them professionally, my own analogue meter at home was 100k ohms per volt, as compared to the 20 k ohm per volt of the Avo. They were good in their day, said day being at least fifty years back. Their valve tester was quite useful too...


Thread: 3 leg hone
29/12/2020 00:18:05

I agree with Noel, they are very useful. The finish they leave is better for rings to bed onto than a lapped or bored finish. Bell mouthing should not be a problem since you should not be trying to remove a significant amount of material. Move the hone up and down the cylinder as it works, taking care not to come out either end.


Thread: Advice please - Brushless motors
22/12/2020 20:41:04

There several different ways to implement a brushless motor. For instance, the combination of a VFD and an induction motor can be said to be a brushless motor. But more usually it refers to a motor with permanent magnets and a solid state circuit instead of a commutator. Typically these will have a fixed stator with three windings on it, and a moving rotor with permanent magnets By applying three phase AC to the windings, a rotating field is created, and the rotor will try to follow it. Varying the frequency of the AC will vary the speed. The simple units in model aircraft use the back EMF from the coils to determine what the motor is doing and so control the AC frequency being sent to it. More sophisticated units like those in disc drives use hall effect sensors to determine the actual rotor position and so can maintain better control. This can give better starting and probably higher torque. I haven't seen what is inside a drill one, but it would be good to have extra torque in this situation.


Thread: Rewiring Li ion battery
21/12/2020 15:19:33

It is vital to charge these batteries correctly, as others have already said. They are not charged with a constant voltage but with a constant current, with the voltage across each cell being monitored as the charging proceeds. The charger will bring each cell up to the fully charged voltage without letting any individual cell become overcharged. This is called a balance charge. You can get chargers that will do this, but it is important to know what the specifications for the cells is. Some can be fast charged at higher rates than others for instance.

Some batteries come with a control circuit built in, others just bring out the inter-cell connections to allow the charger to monitor. The latter type can be charged with the type of chargers the model aircraft guys use.

Even with the right charger, it is a good idea to charge this type of battery in a place where it will not cause too much of a problem if the cells vent and catch fire and to be around to supervise the process.


Thread: Sourcing Handwheels
10/12/2020 04:50:42

Do you have access to a lathe and a drill press? You don't need fancy machinery to cut a keyway, and one for a handwheel is an excellent job to start on since it is not as critical as something taking really heavy loads.

I've described this technique before here, so at the risk of being repetitive... Turn a plug to fit the hole in the hand wheel. Ideally the plug should be the same or very similar to the handwheel material and should be reasonably flush both sides. Locktite it in place. Make a centre punch mark where you want the keyway, right on the line of contact between the plug and the wheel. Drill a hole using a drill just a little under the size of the desired key. Knock out the plug, and now you have have nearly 80% of the desired keyway. Take a file that will fit through the hole and is less than the desired thickness of the key. Carefully file out the corners, using the hole as a guide. You can use a piece of the keysteel as a guide to see when you are getting to a good fit. If the width is the same as a piece of HSS that you happen to have, you can also use that as a kind of chisel to help take out any high spots in the middle. Files do tend to cut more at each end unless you are very skilful with them. I have done a few keyways like this, and with patience you can get a very good job.


The old timers did them like this all the time, as well as cutting the matching one on the shaft with a cold chisel and file. You can do almost any job with hand tools if you are desperate and patient enough

Thread: Heinrici without Castings
09/12/2020 21:56:04

I saw an engine just like those back in my early teens, somewhere in the early 60's. The guy who owned it had acquired it somehow and restored it, although he did not know what it was, and brought it around because my father was known around town as a steam man. Dad was not home, and I was intrigued because I could see it wasn't a steam engine, nor did it have a spark plug, so what could it be?? Not some sort of pump since there was no in or out. When Dad came he he of course recognised it immediately, found a suitable torch for heat and got it going.


Thread: Internal Key-way Shaping
05/12/2020 03:53:45

Here are a couple of commercial shaper tools. One is very like the usual Jones and Shipman type, except if you look carefully you will see that it does not have the built in top rake that is common with lathe versions. The other is what the bicycle crank type is modelled on. The tool bit can be set vertical, at 45 degrees either way, or at 90 degrees either way. The disadvantage of this type is that the tool bit must be long enough to reach right across the inside, so it can't be used once the bit is getting shorter. The one in it is sticking out a bit far , because it can't go any further back in the slot in the fixed piece and I did not want to cut about half an inch off the end to make it shorter. It works fine like that, and as it gets sharpened it will end up with less and less overhang. If you decide to make one, use a steel crank!

The potential problem is not to do with the clapper pivot, it is bending in the tool causing a dig in. I have really only had problems with slotting blades trying to dig in, this is much the same problem as the difficulties with parting off in a lathe.

I've made special tooling to help with doing inside keyways a couple of times, but usually don't bother and do it the drill and file way. This is mainly because it takes longer to arrange tooling than it does to do the keyway, so unless you want to do a lot the same, why bother. One idea uses a piece like a cotton reel split lengthways with flanges on the end to suit the job. The flanges on one end are mostly removed so that the two pieces can be wangled inside the hole in the job, leaving a slot between them just the width of the desired keyway. This guides the cutting tool, made from flat the right thickness, so that the end cannot wobble sideways as it cuts the keyway. This works very well, although it makes it hard to see what is going on inside the job.


Shaper tooling

Thread: The Old One - Broken Tap Removal?
02/12/2020 00:46:10

This advice is too late to be helpful in this particular case, but anyway... I have built and maintained three sailing dinghies over the years, and currently have a steam launch. Naturally this has lead to using a fair bit of stainless over the years. So my general advice is to avoid the use of stainless unless the job absolutely needs it and you know what grade is right. Some grades are easier to work with than others, but it is nasty stuff to work with, and does not always give the corrosion resistance you might be expecting. In particular, stainless threads love to seize up. If this is for use in the workshop, does it really need to be stainless?


Thread: Walton broken tap extractor
29/11/2020 05:17:09

I have managed to get one or two out using a long pointy diamond burr with an air die grinder. A Dremel tool would be suitable too, and the burr I used came with a set of bits for one of those. You work from one flute towards the centre until you have ground away enough that the rest cleans out. Takes a while but can save the job.


Thread: Suggestions for lathe-only projects?
28/11/2020 20:54:53

If you need to you can make all the clamping parts you will need. They don't have to be as pretty as the bought ones to work, and even if you have a set you will often find that you need a custom length of stud for something. Threaded rod is fine for these. Plenty of fine work has been done with just the lathe and vertical slide. A better chuck for the milling cutters is good if you can manage it, for instance an ER series chuck that either screws onto the mandrel nose or has a drawbar through the mandrel. If money is tight you don't need the full set of colletts, only the ones needed for milling cutters that you actually have.

Don't overlook what you can do with hand tools if all else fails. Tubal Cain did a series on machining one of the Stuart engines entirely with hand tools some years back. He bored the cylinder with a brace and bit. That was a bit of a tour de force just to prove that it could be done, most of us would at least use whatever machines we have. But you can do the odd bit with the hacksaw and file if you have to.


Thread: Internal Key-way Shaping
24/11/2020 09:30:26

Clive mentions drilling first, I would agree but I would go much closer to the final size. The bung should ideally be the same material as the workpiece. Fit it flush and centre pop on the joint line. Then drill to close to final size. Maybe 5% under. This takes out nearly 80% of the material. Filing will take out the rest. Although I have shapers, if I only needed one keyway I would do it this way rather than set up to do it on the shaper, which would take longer. Unless it was the one or two sizes that I have already made tooling for of course.


Thread: Unimat 3 motor diode
24/11/2020 03:25:02

Yes, that diode gives the reduced speed on the half way position on the switch. It is unlikely to be the original problem since even if it went short all that would happen is that you would get full speed all the time. It is more likely that you have a problem with an interference suppression capacitor, which you are likely to find inside the motor itself. They are intended to reduce the interference from sparking at the commutator, and would usually be connected to ground, so if they are short, or leaky, or sometimes just too large they can trip an earth leakage breaker.

If that is the problem, make sure that any replacement is of the correct voltage and service rating as they are across the mains and so require to be rated for 240V AC. So a DC rated capacitor is not suitable, even if it has a higher voltage rating.

It is also possible that the motor windings have gone leaky to ground. Unimat motors get worked quite hard and it is easy to get them too hot. That is why I have two dud ones lying around, and the machine now has a small three phase motor with a VFD.


Thread: Tig Welder
20/11/2020 21:15:23

Hi Alex, Maybe I should clarify, when I said HF I meant High Frequency start, not Harbour freight.

With HF start there is a high frequency source in the welder which will start the arc before the electrode touches the job. With simpler welders, you have to scratch the electrode on the job to get started, which risks contamination and sticking. It is a very worthwhile feature, especially for learners, who will spend enough time resharpening electrodes without having to touch them to the job deliberately.

When you do touch the electrode to the job while welding, there will often be a bright flash and the arc will change colour, with steel to a pretty shade of blue, with copper to green. The only thing to do is to stop immediately, clean the job and put a new point on the electrode. There is a tendency to hope that it might come right, but it will only get worse.

My first major task for the welder when I got it was making up some stainless steel tanks for my steam launch. The material is about 1mm thick. The first tank I did had flanges and I found that trying to do a lap joint was very hard. It is better to avoid flanges and just do a butt joint. I wouldn't put myself in the same class as the welds in the pictures shown above, but I can get pretty acceptable results. Aluminium is harder, I can sometimes get that nice "stack of dimes" look, but not consistently. I think that you have to realise when the job is starting to get hot, and stop for a bit before proceeding.


Thread: Basic Maths: A Lost Art
20/11/2020 20:47:27

Gas turbines are a machine that can be run at a higher power than nominal for a short period of time. So if it is rated in terms of maximum continuous power, it may well be capable of more than 100% of that, for a short time. This is actually a useful feature for aircraft, where the ability to get a bit extra for takeoff is quite useful. (Of course they are usually rated in terms of static thrust.) The space shuttle main engines used to be throttled up to more than 100% for some parts of the ascent too. But then that was a pretty dodgy machine at the best of times.


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