Member postings for John Olsen

Some machines did have lifting mechanisms, but they don't seem to be really necessary, and I think especially not for amateur use where we are not generally doing long production runs. The tools seem to last fine even if they do drag backwards over the surface and are simple to sharpen. Even carbide doesn't seem to mind.

I've done T slots with the cutter locked, no problem. Home made T slot cutters for the shaper are cheaper than T slot cutters of the mill, and much easier to sharpen.

For vertical facing, if you angle the clapper box correctly it will let the tool swing to clear the face on the return stroke. Same applies to dove tails.

You can use pretty much the same cutting oil on a shaper as you would on a lathe, with the added advantage that it won't try to fling it at you quite so much.

John

After owning several inkjets over the years, I concluded some years back that they are a ripoff and a complete waste of time. So I have a laser printer/scanner for black and white, and I get colour prints done by the photo shop, they can do it cheaper and better than I can. One of my experiences was having a brand new set of cartridges that never actually printed anything because the heads never came clean.

I would certainly recommend against anything from HP, they have gone over to the dark side, and are not the same outfit that used to make such excellent test equipment 40 or so years ago. That side of the business went to Agilent.

John

I didn't know that you Brits used 110 Volts on building sites. The idea intrigues me since in fact 110 Volts is not actually a lot safer than 230 Volts. Both are quite capable of delivering a lethal current through your heart, especially if your skin is damp or sweaty, as it might well be on a building site. There are 400 deaths and 4000 injuries each year in the USA for instance. 230 Volts might be a bit more likely to kill you but I would not risk my life on the difference.

What we did in NZ, which I would not claim as perfect either, is that you are supposed to use an isolating transformer. This gives you a secondary which is not earthed, so that it takes two faults rather than one to create a dangerous situation. Eg one side has to be accidentally grounded while the other side touches you, or you have to be touching both connections. But that meant a bulky transformer for every tool, so in their kindness they allowed the transformer to have two outlets. That of course doubles the chance that one of them is faulty. I prefer RCD's myself, especially since it is so easy to check them, Battery tools are also good.

John

They don't have to be sharp at the top and I think it is better if they are not since the rubber belt has a small radius at the bottom of the groove. You can find details of the shape in makers catalogues. There are several different sections, for instance PJ section is a 40 degree angle and the spacing of the grooves is .091 thou.

Pulleys are not hard to make, or else they are sold in a range of sizes and widths. The belts are sold to the width you order, they have a wide piece for each standard length and cut it to the number of ribs you need. The belts don't need a lot of tension and run quiet and smooth. They will go around smaller pulleys than V belts.

John

OK, not on a traction engine, but my steam launch has two pumps driven by levers off the cross head, so the pumps are working at engine speed. The rams are about half inch diameter and the stroke is about two inches. The bypass is just back into the suction side, and I would say that the main drawback of this is that you can't see the water squirting back into the tank, which tends to assure you that the pump does work. I've got a couple of small pressure gauges on the delivery side which allows me to see the pressure pulses when they are pumping, but theses need to be turned off mostly to avoid thrashing the gauges to death. The copper pipes too and from the bypass valves are long enough that I don't think heating of the circulating water is going to be a problem. The engine runs at up to about 600rpm at full speed, so is often cruising at 4 to 5 hundred rpm

The engine speed pumps do have their problems, the main one I have had is the seals on the rams not lasting very well. They started out as standard O-rings, and were replaced with hydraulic type U seals. Those seem to last better, but not as long as I would like. It may be that the initial finish on the bores was not as good as would be nice, but they should have polished themselves by now. The ball valves have stood up to it really well. The seats were initially burnished with a spare ball held in a recess in a piece of brass rod. The lift is limited as it should be.

Long term I would like to come up with a geared down pump setup, but I can see how this might not be ideal for a scale model like the traction engine guys have.

John

It seems a pity to go to a lot of trouble to make an aluminium pulley which will not really perform any better than the original plastic. Mine used to do tricks like grabbing the belt and wrapping it twice around the small pulley. The round belt is not really up to the job. My solution was to make a toothed belt drive which fitted inside the original cover. It works really well. I did all the work on the Unimat, including milling the teeth. I do have the milling attachment and the simple dividing attachment. The hardest part was that one of the pulleys needed 41 teeth, which can't be done with the dividing attachment, so that was done by wrapping a strip of tenth inch graph paper around the blank and marking out from that.

John

The sensible heat of the incoming steam is higher than that of the exhaust. The latent heat is as close to the same as makes no difference to us, and since we would only want to condense at the cold end anyway, that is the figure that matters to us.

There is still latent heat discarded in the suoercritical plants, since the latent heat that is thrown away is at the temperature and pressure prevailing in the condenser, eg near enough to 0psi and around 25 degrees C, depending on the source of the cooling water. But it will be less than in lower temperature and pressure plants, since less total weight of steam will be required for a given output power.

There is no power to be obtained directly from latent heat, since there is no temperature difference between the gaseous phase and the liquid phase. It follows from Sadie Carnots formula that the efficiency of the plant would be 0%. There is a trick you could do, if you had say a large supply of water at 100 degrees C, and another supply at room temperature, say 25 degrees C. Once you have excluded air from the system, the hot liquid will vaporise and flow to the cold side, and you can use the flow to generate power. But that is actually using the sensible heat, the hot side will get cooler unless you keep pumping in heat.

There have been efforts to find better working fluids than water, but all of the likely candidates have disadvantages much worse than the relatively high latent heat of water.

John

Have to disagree with you there Hopper. The latent heat is usually a total loss. It goes up the chimney on a loco or traction engine, and is lost in the condenser on a condensing engine. Maybe I should say deliberately rejected on the condensing engine, since it is by getting rid of the latent heat that we are able to get a vacuum. So for every pound/kilogram of water we evaporate, there will be a fixed loss.

So it follows that to increase the efficiency we want to reduce the amount of water we need to evaporate. One is to raise the pressure we are working at, which will increase the temperature of the steam and reduce the amount of steam we need to generate the required amount of power. The other way is to superheat the steam, which will reduce the weight of steam needed to fill the cylinder on each stroke, without changing the pressure. So we can get the same amount of work from less total mass of steam. Superheat will also reduce cylinder condensation, often making the engine more lively.

The latent heat can be used for things like process heat in industry, or for district heating schemes. The downside is that the higher the temperature you want the process heat at, the more back pressure you must tolerate on your engine.

John

The point of the shunting up and down would be to build up enough pressure to operate the blower. This would increase the draught on the fire, helping to get the temperature up quicker to make actual steam. Forcing the boiler like this is of course not the best for it, but operational emergencies quite often outweigh long term considerations. Ideally you would bring the boiler up to temperature slowly. Some places had provision to connect an air compressor to the boiler for this purpose.

John

Some of that machine looks to have come from the same foundry as my 18 inch Alba, and yet a few parts are quite different, eg the gearbox. The Alba did end up under the Elliot name as well. I expect that there may have been some badge engineering going on. You have the same vice as mine too, which is good, they are often missing from shapers.

The finish can depend a bit on the material you are cutting too, cast iron and aluminium are easy to get a great finish on, steel can vary a bit depending on the grade, much as it also can with a lathe. Don't let those smoking chips go down your shirt front!

John

I've just watched the "I do cars" video referred to by a couple of people above. In the comments someone mentions that apparently there is a special oil that you are supposed to use that does not degrade the belts. So that might be worth looking in to. Apparently in the states you can't get that oil so even the dealers are using the wrong stuff.

There was also a comment about an aftermarket conversion of both belts (Timing and oil pump/balance) to chain, which would seem like a good idea, although tossing the whole thing and getting something Japanese would seem like a better one to me.

The "I do cars" videos are fascinating if you want to see what various forms of neglect can do to an engine, often big American iron, but German and Japanese engines do feature from time to time.

John

The base on my original Emco one is 30.8mm wide by 69mm long. It mounts by means of a single capscrew 17mm from the end, with a boss 12mm diameter that engages in the recess in the cross slide.

The scale is about 25mm diameter, but is only on the far side, eg when the compound slide is set up with the handle on the right. This gives an arc of a circle that goes to plus and minus 40 degrees. There is an extra mark on the cross slide to allow greater angles to be set, but the marks on both the cross slide and the compound are wide enough that you wouldn't be using them for anything really critical.

I'll take a couple of pictures and post them shortly.

regardsd

John

You guys might also like this video, which shows a selection of steam boats and ships from around the world. It includes the above mentioned Monarch and Waverly, although it somehow manages to miss out my own "Dancer:.

v=RH0LwfyruLE >**LINK**

regards

John

My ML7 has had the Newton Tesla drive on it now for over twenty years. It has not seized yet. Of course the way that it is set up, the new maximum is only about 20% higher than the old maximum, and it rarely does that since most jobs don't need to be turned at maximum speed. Only tiny diameters need to be turned fast, and I have a unimat that is better adapted for that kind of thing. I did do a mod to the Myford part way through its time with the VFD, it now has a four stage pulley setup, using poly V belts, instead of the three stage V belt setup it had from new. The poly V belts actually put less load on the bearings, since the belt tension needed is less. It also gives me a lower bottom speed. Even with the VFD, it is useful to have a wide range of belt ratios, since the large diameter slow jobs tend to need more torque. The poly V belts are great, they don't heat the pulley up the way the old V belts did, so much less power is being wasted in friction.

As Peter has said, the VFD is especially useful when low speeds are needed.

Hemingway do a kit for putting Poly V belts on the Super 7, but if you want to do it to an ML7 you are on your own. Maybe I should make some drawings of what I did!

John

The main effect of using single phase will be that the peak current through the rectifier and the ripple current in the smoothing capacitor will be higher. Since Mitsubishi has said that it can be done, they must have specified enough capacity in the devices for this to be Ok,. It should not need any external devices.

John

I suggest you take a look at a Youtube channel, "I do cars". The engines he takes apart have generally suffered catastrophic failures. To be fair to the manufacturers, most of them are due to lack of oil. lack of coolant, or just outright abuse. The engines he autopsies are mostly American, although some Japanese and German engines have appeared.

Interesting what Clive says about bolts working in shear, I had the impression that this was not actually regarded as good practice. It is better to use dowels to locate items and take any shear loads, and leave the fasteners to hold things together. Part of the reason for this is that a bolt has to have some clearance in the hole to allow it to go in without damaging the thread.

John

There is a technique for turning small ball shapes which might work for this. You take a piece of silver steel rod a little larger than the ball size, and drill a hole in the end a little smaller than the ball size.Face the end and then harden. Fit the other end into a file handle, and arrange a rest in the tool post close to the job. Having roughly formed the ball end with a 45 degree chamfer, use the hand turning tool to form the ball, moving it around the end of the job so that it can cut. The circular cutting edge on the inside of the hole will form the ball. The outside edge is not a cutting edge and should never contact the job.

I've used this technique to form ball ends on tiny handles as small as about 1/8 inch or so. A refinement is if you can manage to face the end back at an angle to give some relief to the cutting edge. This sort of tool will work for a range of sizes, the smallest being the size of the hole.

Otherwise, you can make a form tool from gauge plate by drilling a hole the size you want and then cutting away the bits you don't want to leave a half or quarter circle cutting edge.

Case hardening should be enough for the tappets for a vintage style of engine.

regards

John

I think the standard gauge tracks were 5 feet across the outside, until someone realised that with flanges on the inside that the inside measurement was the critical one that should be specified.

Unless the rules have changed since I studied them, the decibel is a measure of power ratio, so has no direct correlation to Pascals, unless you state the base for the ratio. So if you specify dBa then there would be a relationship to sound pressure level in Pascals. But if you specify the loss of an electrical attenuator in dB, then there is absolutely no relationship to sound pressure level at all. The loss through the attenuator would be the same number of decibels no matter what signal you put in, provided it is less than the maximum power the device can stand. In telephony and radio work we used to use the dBmW a lot, this is the ratio of the measured signal to 1mW, so 1 Watt would be 30dBmW. The dBa mentioned above is used for sound pressure level relative to a fixed level, but with the frequency response weighted to match that of the hypothetical average human ear.

John

Funnily enough I once had an HP logic analyser given to me, but it had no probes, and I never managed to source any or find out what was in them. So I ended up giving it to someone who had a collection of HP stuff. But now I have one of the Kingst USB logic analysers, and it works fine. Mine is the cheapest model. You can get their software and run it in a demo mode to see how it looks. I have no connection with them, other than as a satisfied customer.

John

You can easily get hold of one to play with, for instance many of the introductory kits available for the Arduino include one, along with temperature sensors and other fun devices to play with. No soldering required you just hook the devices up with a breadboard. Some of the chips include a magnetic compass as well.

John