Member postings for John Olsen

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.

John

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.

John

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.

regards

John

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.

John

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

John

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!

John

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.

regards

John

I noticed in Switzerland a couple of years back that on some curves the sleepers are laid at an alternating angle, so that one end of each is adjacent to the next sleeper. Like this VVVVVVV instead of this I I I I I I I. Presumably this is also for lateral resistance as it generally seems to be on curves..

Some of the Swiss lines also have an extra rail down the middle, with gear teeth cut in it.....

John

The editorial comment on the front page photo mentions a promised article on the engine, unfortunately this does not seem to have ever been written. So probably there are no drawings available. The best way to proceed if you want to make something like this would be some study of the old Model Engine News site, no longer being updated but still online. Model Engine News

Otherwise you could see if you can contact Dean as mentioned above. If he doesn't respond to a message here I could give him a ring...(he is local to me.)

regards

John

I've dug out the 1950 issue, this also refers to another issue#2572 with a report of the exhibition where the engine appeared. In that one there is another photo and a description of the engine. If you want to send me with a personal message with an email address I can scan those for you.

I don't know what your interest in this particular engine is, but Dean Clark who posts on here occasionally builds a lot of two stroke model aircraft style engines, including multicylinder, up to a supercharged V12, which you can find pictures of on this site. He would be a good contact if you are interested in this sort of thing.

regards

John

Hi Shane, If you search for Model Engineer index you should find a site that has a searchable index at www.itech.net.au A search on that for Boler gave me about 10 hits, including the 1950 cover. There is also a 1948 cover of the "Ensign" 10cc engine by the same guy, and references to models of his at exhibitions. He went on to build a working 7 cylinder Gnome engine which won the Championship Cup at the ME exhibition, so was evidently a very skilled worker.

I would have most of the issues found in the search so could easily scan pages for you if you are interested.

John

!2 inches to the foot model steam launch "Dancer".

Here's a tip for anyone using commercial compression fittings on copper tube, which I guess would only be on larger locos, or on a steam launch like mine. They come with the wrong sort of olive, the ones meant for nylon tube, at least the ones I have bought generally did. It turns out these will sort of work on copper tube, at least for a while, but are likely to start leaking, usually in an awkward place to see. Of course I didn't know this at first!

The ones for nylon or plastic tube have a short taper on each end and then a step up to a larger diameter in the middle. The ones for copper have a longer taper at each end that meets in the middle.

If there is information in the 1940's ME about model size fittings, I probably have the issues here. I have some wartime ones, and a pretty complete collection from 1944 until covid started.

regards

John

I wonder if the problem with the early transistor amps that SOD mentions was actually due to residual crossover distortion? Most transistor amps were class B or at best class AB, to make the most of limited power ratings. There was a lot of work done on this about 40 years ago as MOSFETS started to emerge. Wireless World around that time described a transistor class A amplifier which was claimed to give excellent results, but at relatively low power.. If a Class B or AB amplifier is not set up quite ideally, there can be a little glitch in the waveform as it crosses over from one output device to the other, and this is a particularly harsh kind of distortion.

One problem with the transistor stuff was transient intermodulation distortion, where the early stages of an amplifier can go into overload until the slower power stages catch up. The solution is to try to reduce the reliance on large amounts of negative feedback around the whole amp and instead to try to get low distortion in each stage, as well as trying to have good high frequency performance in the output stage

The way they measured transient intermodulation distortion was to apply a fairly large square wave (but not enough to clip) along with a lower level higher frequency sine wave. At the output, the sine wave would be liable to disappear for a bit after each transition of the square wave. An ordinary distortion test with a sine wave input will not show up this sort of problem.

The first place I worked was the Civil Aviation part of the local Ministry of Transport. They used to say to us trainees that 5% distortion was perfectly acceptable, and so of course I made myself unpopular by pointing out that they were applying this to every item in quite a long chain, the mike in the aircraft, the amplifier in the transmitter there, the same in the receiver on the ground, then any amplifiers needed to drive the landline to where the controller was sitting, and his amplifier and speaker. To me the end result has always sounded like Donald Duck, and I have never been able to understand what he was trying to say either. Just as well I never tried to be a pilot! Of course this sort of thing was probably a factor in the Teneriffe accident.

John

The usual feed system uses a ratchet wheel that has square teeth. The spring loaded pawl that engages with it has an angle on the end, and can be rotated so that the ratchet drives in either one direction or the other. There is a slot in the tube that engages with a pin through the pawl. So in normal use, when the cutter has passed the end of the job, you pull the pawl back against the spring, turn it through 180 degrees and drop it back into the slot again. Usually you then need to rotate the manual handle to take up the backlash so that it starts driving again to pass back over the job in the opposite direction. At some point while the cutter is past the job, you can wind on a bit more cut. Unless the shaper is running very fast, you can generally do this without stopping the machine.

When you don't want the feed to drive, you pull the pawl back out of the slot and turn it through 90 degrees, this stops the pawl engaging with the ratchet wheel.

Some machines have provision to change the stroke of the feed system, so that the pawl picks up one, two, or even three teeth on the ratchet, giving a coarser feed.

John

It depends on the diameter of the aluminium, but 435 rpm does sound a bit fast for the minimum speed. It would help if we knew what the actual lathe is too.

If the existing motor is a single phase induction motor, then you are not going to be able to change the speed of that. You would need a three phase motor with a VFD, or a universal or DC motor with some sort of electronic control. You can buy a plug and play setup for the Myford, for instance from Newton Tesla.

It might be easier to do it mechanically, for instance an extra countershaft with stepped pulley to allow lower speeds. For example, the Myford ML7 that I have came with three steps on the spindle and a countershaft, but also had quite a large stepdown between the motor and countershaft. (It also has a back gear.)

Bear in mind that just changing speed electronically has its limitations. When you reduce the speed, you will still only get about the same maximum torque. So say you double the diameter of the job, you would halve the speed to get the same cutting speed. To take the same depth of cut, (same force on the tool) you would now need to double the torque, but with an electronic control you can't. Whereas if you halve the speed by changing pulley sizes, halving the speed will double the maximum available torque, so you would be able to take the same depth of cut. This means that you would actually be able to remove the same volume of metal in a given time.

John

You may already know this, so sorry if I am teaching my grandmother how to suck eggs here, but it is important for the holes in the bedplate and the cylinder block to line up. One way to do this is to make a jig plate which is just a bit of flat stock with the holes drilled in it. You use it twice, once to do the holes in the bedplate and then again to do the holes in the block. If both sets of holes match exactly, the columns will go in without side loads, which makes assembly easier.

The other thing that helps is if you can make all the columns themselves exactly the same length between the shoulders that seat against the bedplate and the block.

regards

John

It seems to me that what is wanted is a material with high permeability and low remananent magnetism. In less technical terms, you want a high amount of suck when the electromagnet is on, and a low amount when it is off. If it retains too much magnetism when the electromagnet is off, it will tend to stay in the same position even when released. Some relays had to have a little brass pip that made a gap when the moving part was pulled against the pole piece as otherwise they would pull in and never release despite the springs.

Anyway, soft iron is generally the most commonly available material that will fill the bill. Transformer laminations are also a very suitable material, and readily available from scrapped transformers, although only in thin sheet form. You may want to stack up a few pieces if you use that source.

regards

John

A separate mill will be better, space and finance permitting of course. The trouble with combination machines of any sort is that they are always set up for the wrong function, so you spend a lot of time changing back and forth. Especially when a part needs turning, then milling, then more turning...

On the other hand, the kind of light milling that you can do on a Myford with a vertical slide won't do it any harm. Plenty of good work has been done that way.

Another thing to think about is the kind of work you want to do in the unforeseeable future. A vertical slide will do good work but will limit the size of the jobs more than even quite a small mill.

The usual sort of small vertical mill will act as a drilling machine, so takes the place of another machine you might want later if you went the vertical slide route.

Regards

John

You want a different rake for drilling brass and bronze, which can be achieved by stoning the cutting edge with a small stone. So not actually blunt, but with the opposite rake to what you would use for steel. On a drill the rake for steel is built in by the spiral angle but it is enough just to stone the cutting edge back so that you can see a small flat on the spiral side, not on the end.

If you think of it like lathe tools, for steel the top of the tool slopes up towards the cutting edge. This peels off those nice spirals. On brass, such a tool will cause a large force dragging the tool deeper into the job, so by instead sloping down towards the cutting edge we reduce the dragging in force. The brass will sheer off in small chips and everything will behave itself.

The rake does not need to be very large, maybe 5 to 10 degrees. Ideally you would have a separate set of drills for brass, and I believe drills have been made with a different spiral angle for brass, but modified normal drills are fine for most amateur work.

John

Edited By John Olsen on 14/12/2021 02:30:21