Member postings for Paul Kemp

There doesn’t look to be anything fundamentally wrong with your knife tool but the picture is a little blurry, the grinding marks on the top look quite course, what grit wheel have you got on your grinder? However if all the other tools you tried gave the same or similar effect then it’s probably not your tool! You mention changing rpm, tools, with and without cutting oil but no mention of feed rate, did you try altering that? As a test did you try different depths of cut? Does a heavy cut produce the same finish as a light cut?

As Jason says it’s likely the grade of steel you have, some low carbon steels tend to tear rather than cut, EN3B can be like that. However it should be possible to get a better finish than that although mirror finish is probably unlikely. It’s counter intuitive but upping the feed rate may give an improvement. Looking at the work piece pictures the deeper scores suggest maybe chips got trapped between the tool and the job? Flood cooling may hep that but I don’t suppose you are geared up for that?

As to improving the finish on non critical parts light use of a fine file followed by emery but mind your fingers

Paul.

predictive, chops for chips,

Edited By Paul Kemp on 29/08/2022 22:57:51

If I were making that I would rough out the steps with the raw bar in the chuck at the same time as putting the centres in, hold on the largest diameter in chuck, face, centre, rough out steps and reverse to do the other end leaving diameters say 0.5mm oversize and lengths maybe 1mm depending on the width of the undercuts desired. Set up between centres, finish turn centre and stepped diameters. Grind a tool like a parting tool but with a radiused nose for the undercuts, working from the end kiss the step with the tool, measure the length with the vernier from the end, use the top slide (set parallel with bed) to advance the tool the required amount and put the undercut in, repeat for second and third measuring always the total length from the end (saves tolerance build up) Reverse the shaft, set your dog on shim as you suggest and repeat for other end. However I would be leaving the centres in so you will need to add an allowance to machine them off after.

Paul.

Chris,

I don’t think that’s quite fair regarding your how much does it cost me question, there were several answers giving you ideas on how to measure your electricity usage in the shed. How much that energy actually costs you if you measure it is in your court depending on how much your supplier is charging you and if on variable rate at what time of day you use it. You can estimate it from the ratings of your machines and lights and time the usage or you can measure as suggested. I don’t think anyone could have reasonably been expected to give you a quantified answer in £’s and p’s?

Personally it’s down to cost benefit. How much enjoyment do I get from making stuff and can I afford it, if I can pay the bills I can afford it so I don’t care what it costs. If I can’t afford it then I have to find other savings to support or pack it in.

Paul.

Wouldn’t a drip feed oiler normally have a small sight glass below the reservoir so you can set the feed rate? Ie drips per minute? I haven’t come across many drip feed lubricators outside my myford ones and full size hydrostatic ones on loco’s and they all have sight glasses to set the rate.

Paul.

Last time I spoke to Scottish Power their wind energy capacity was being sold at around 7p /kWh even at that ROI for a wind farm is a little over 5 years.

Paul.

SOD, you say world prices are driving the increase, yet our friend across the pond is not suffering the same percentage rise? How is the American / North American market insulating itself?

Given that we assume the cost of extracting North Sea gas has not risen dramatically then surely legislation can be passed that gas used in the domestic market must be sold at a reasonable profit and directed at the domestic market with a punitive export tariff applied if it is sold abroad? The extraction companies may well be investing in its extraction but it is a uk resource and therefore should be used to support the UK first?

Paul.

That is less than 1/3 of my current peak rate - on an economy 7 type deal we pay £0.34 /kWh. So much for global parity set by supply and demand lol.

Paul.

Jason,

Any of the items listed in your last para are definitely fair game to be deleted, none of those subjects are remotely related to model engineering or common morals and that is taking my point to extremes

It’s the locking of threads and deletion of links I am not keen on. It’s been raised by others at various times. It is simply my opinion that while I accept this as a condition of no charge to me to use, I would not be happy to pay (by donation or other) on those terms. I have no issue in putting the magazine articles or archives behind a pay wall, I used to be an ME subscriber years back followed by an occasional purchaser of ME and MEW but I stopped because there was little in either that interested me enough to buy them, so why should I have access for free. As others have pointed out the forum offers mutual benefit so contributors can benefit in kind.

You are indeed correct about the relative number of postings between the two examples, probably also the number of active members. It’s perhaps also a narrower subject band which does not encourage such a diverse discussion scope. The atmosphere is however more of the beer tent than the tea room where the foreman chases everyone back to work, .

CHAS LIPSCOMBE, I can’t see having re read several times how my comment was related to people buying the magazine? I was merely stating I would not donate if the censorship rules remain the same, quite what that has to do with subscribing to or purchasing either magazine eludes me.

Jason, it’s very rare politics gets discussed on TT in any of the categories unless it is directly or slightly related to the purpose of the forum, however when it does rear it’s head it is allowed to take its course. I cannot recollect a single thread that has been shut down? Also there is the occasional post advertising a new business or a even rarer a product, again these are left unmolested, in fact a link to a business has been very useful to me recently. Personally I find it seems to muddle along quite well being “self regulated”. Granted it can be a bit rough round the edges, it’s a bit like the playground without the dinner ladies!

Paul.

But TT does not have anything like the censorship on here, I don’t mind donating to an open forum but I wouldn’t donate to this one unless some of the restrictions were lifted!

Paul.

Nigel,

Drawings are not always all they are cracked up to be either! I am building a half size Little Samson to Edward George’s drawings and to his credit as model drawings go they are pretty good but I finally got to assemble up the motion Saturday to find one issue definitely of my making but another I can’t fathom out! The eccentrics turned out to be about an 1/8” out of line with the expansion link, drawings have been followed on all the relevant bits so I can’t see how it ended up like that. Luckily I have a fairly simple fix but it made for a fairly “clanky” first run on air having to leave the eccentric rod palm bolts slack to accommodate! Was determined to get it turning though after 6 years work, remedial works in course of being applied!

**LINK**

Determined to get it in steam for next year!

Paul.

Ramon,

lol, I am afraid it was my rather obtuse sense of humour. I was just surprised given the frequency loctite and similar products get suggested on here that no one had chipped in with the familiar cry “loctite” so I thought I would cast the line! For the record I wouldn’t seriously consider it for this application either but do bear in mind that there are various grades of the stuff and it’s not necessarily for ever as some can be separated by application of relatively mild heat.

Quoting you “No one in the right mind would use Loctite to fix a flywheel in place. Loctite has its right place in engineering but this is not one of them - That would make the flywheel and crankshaft a one piece item to my mind. Whilst not an actual issue it's just not a direction someone making a representation of a full size engine should consider to my mind. Once it's on it's on and IF it needs to be tweaked there's no chance.” If someone is making a representation of a full size engine though why not use the techniques used on the full size? Is a grub screw or two more heretic than a blob of loctite? Neither mirror the prototype

On the closed keyway / gib head key issue I have seen that done on line shaft pulleys but by and large I would agree with you this is not a very common way to fit that type of key.

Martin,

I don’t see any issue at all in reversing the taper and applying it to the shaft, should be exactly the same effect.

Paul.

The key to this conundrum is as Jason’s last drawing above if you are fixed on a parallel keyway in the flywheel. Do as Jason indicates with a parallel key and keyways and two small grub screws, that removes any risk of tilt and the angle of the screws oppose each other so it should never move.

The second option is do it as per full size with a tapered key and keyway using a broach and suitable tapered bush. Again if the tapers match and a bit of careful filing will ensure that, whack it in and again it’s not moving.

On some of the other comments; I must be missing something as I went back to the first drawing and it didn’t suggest to me the key would be short. A key drives on the flanks, not the top and I was always taught a parallel key should have top clearance (I have fitted a few on propellers and couplings etc over the years and no one has ever complained it broke or fell off). As stated by Jason a tapered key in a parallel keyway will always come loose.

Finally no one mentioned the modern engineer’s friend - loctite!!!! No grub screws required. The key or keys can be any shape you like. For me the second option would be the way to go (broaching will let your lathe breathe a sigh of relief) but it’s not my engine and not my lathe.

All the best,

Paul.

There is absolutely nothing wrong in aspiring to renewable energy, it makes sense on lots of levels but the fact is in terms of transport there is nothing available with equivalent levels of energy density and safety as diesel for some applications. There is a lot of smoke and mirrors with the greenness of certain alternative fuels that may have an overall low global CO2 profile but in reality still have significant emissions at the tailpipe (methanol or ‘green’ methanol in the shipping arena for example).

The plain fact is developing and implementing renewable power requires investment. In the same way as if you lend your money to a bank in return for interest, investors in renewable power have an expectation that not only will they get their money back but they will get back more than they put in. The costs of implementing renewable power are not limited to the hardware that transforms whatever fuel you choose to use but also the cost of complying with existing regulation or in terms of new technology developing new regulation to ensure the alternative fuel provides an equivalent level of safety to that we currently enjoy. Regulators by their nature are conservative in their attitudes and to a degree risk averse (understandable because if you approve a system and it blows up it looks kind of bad!).

So to make the progress that is desired, first we need money from investors being able to demonstrate they will see a return, government subsidy (free money, except it isn’t as all of us pay for it) and a proactive approach from regulators that is enabling whilst maintaining acceptable safety.

The bottom line is renewable energy in whatever form is going to cost all of us more and that is not what we generally want to hear! Look at what the increasing cost of conventional energy is doing right now! I don’t hear anyone saying this is good because it will make renewable energy cheaper in comparison!

Paul.

1. (Demand has risen) - has it? Limiting this to energy and comparing 2022 demand to 2019, has demand risen significantly? The overall demand may have risen slightly in the UK but certainly not in the order of magnitude to rising costs. Globally the demand for gas has risen compared to 2019 particularly in Asia where there are many new gas powered generating plants coming on line. There was an article in the economist earlier in the year suggesting that if Asia demand for gas continues on its current trajectory by 2025 (if I remember the date correctly) their requirement would equal the entire world production in 2019. a (holidays) is irrelevant, aviation demand for fuel has not yet returned to 2019 levels. b not really relevant as returning to full production only takes us back to where we were in 2019 and in fact many areas world wide have not returned to full production (chips). c nonsense non specific reason.

2. (Supply has fallen) - a true in the UK with regard to coal fired power stations and also lack of investment in nuclear with no clear plan as to how to replace the declining fossil fuelled producers with green solutions in the UK to meet demand without relying on imports (see below). b true as although we were not taking large amounts of Russian gas we did end up even indirectly taking oil and believe it or not coal (it’s not green to dig our own but ok to take someone else’s already dug). c nonsense non specific reason.

The clear answer is UK is an island but not a self sufficient island insulated from global impacts. While we may have only taken a small percentage of gas from Russia we took a significant amount from other sources in the world (Isle of Grain gas terminal with LPG tankers pitching up weekly!). Because these other sources have no come under pressure the supply / demand economic argument comes into play - because there are more customers for the available product the supplier is able to charge a premium. Same scenario with oil. On imported electricity as the exporters are under pressure at home (Europe) they are not of a mind to sell electricity they also need cheaply - remember the recent record price for a short period in the heatwave? If someone is digging you out of a hole you generally have to pay for it!

When the oil price went negative for a short period during covid no one was screaming out to recompense oil companies for losses and yet now it has risen and is at a premium (now dropping again) everyone is complaining about profits. Also with retailers it’s worth noting that it is usual practice in the oil / fuel market to hedge or buy forward, poor decisions or gambles committing to many tonnes of product when the price was high means it needs to be sold high.

There is no great mystery to any of it.

Paul.

Ramon / Jason,

A well fitted taper key should not “tilt” the flywheel on the crank if there is a little clearance. As long as the taper on the key matches the taper in the flywheel it acts to accumulate any clearance on the side of the shaft where the key is located pulling the other side uniformly against the shaft. A grub screw on a parallel key unless it is located in the centre of the length of the key is more likely to tilt the wheel.

“Broaches are fine - if you have them and the means to use them but they still don't cut a key on a taper - not that that is necessary as explained above and confirmed by Jason's comments - the key, from one side only, will induce tilt no matter how good the fit of flywheel to shaft. If you really want a tapered key as you show - to tighten the wheel to the shaft - then you need to do one at each side“

The flywheel on my half size TE is around 16” diameter from memory, it is a sliding fit on the crank so there is minimal clearance (I needed to be able to get it on easily) and it was machined bore and OD at one setting so it runs true. When fitted to the crank and the single tapered key is driven home it has about a thou eccentricity and about half a thou “tilt”. Single taper keys are common in TE construction.

For two keys at 120 degrees Jason has it, make your own bush tapered at the bottom for the broach slot and cut a second slot for a key at 120 degrees. Broach the first keyway, rotate bush, insert a key to locate and then broach the second. My crank has six splines on the end for sliding gears. The splines on the crank were cut on a Bridgeport with a dividing head. For the gears I made a bush as described above and rotated 6 times to cut the grooves with a broach. Needed a little hand fettling on the radius at the root of the splines and some polishing but the gears fit nicely in all six locations.

Paul.

Your drawing there shows the top face of the key tapered by 1 in 100. It is what is normally termed a gib key. The keyway in the shaft is parallel in all directions the top of the keyway in the flywheel should be cut to the same taper. The key is then hammered home and the tapers lock to ensure the flywheel is fixed. If that makes sense? To cut the tapered keyway in my TE flywheel I made the broach bush to the required taper such that when broached (in the right direction!) the top of the key way is automatically tapered. You can check the mating fit on assembly with engineers (micrometer) blue, not marking blue!

Paul.

As you have a lathe can you not find one inside a bit of bar you have in the shed?

David,

I very much doubt you will need full opening on your ball valve. If you think about most regulators the steam port area exposed when open is not equal to steam pipe bore. Unless the bore of your valve is particularly small I think you will find you will be going like the clappers before it is half open. As long as you get an area equal or just larger than combined port area you should be fine.

Paul.

Peter,

The age old debate, how to lay up a miniature steel boiler! The basic question is as you say, full or empty. If it’s going to be full, then my approach would be on the last steaming before you let the fire go, blow down about half a glass and then as the fire dies down fill it - right up to the top with well treated water, right to the very top! Idea being to get as much water in to dispel as much oxygen as possible and with it still in steam the boiled water should have the minimum free oxygen content. I know a fellow with a 4” Foster that fills to the brim every winter and his boiler is still on the original tubes and is in exceptional condition.

If it’s going to be empty, then it needs to be exactly that, empty and DRY. This on a small boiler is hard to achieve as unless you have a decent manhole and wash out plugs it’s very hard to get the air to circulate within to get it dry. While some hold hands up in horror one way to get it dry is to light a small wood fire (SMALL!) to get a little heat into it to drive off the moisture - if you are careful you are not going to heat it up to the point of damage, you don’t want a steam raising fire, just a small warming fire!

If you are going to use steel tubes, quality is very difficult to maintain but to last you need good known material. There have been innumerable reports of latter day boiler tubes not lasting the distance, a few full size have suffered tube failures in 2 years in extreme cases! There is on the web a very good report dating back to the 80’s if I remember rightly where they conducted a detailed metallurgical examination on a marine boiler smoke tube that suffered localised corrosion and under the microscope they found the material at the pit held an impurity inclusion from the steel production and mill drawing process. I would strongly recommend finding a supplier that sources the material from a reputable mill that is making steel from the ore, not recycled scrap and try to get a certificate that evidences the source, still not guaranteed but probably the best you can do.

The last bit (which is also controversial and subject to many opinions) is water treatment. Some love it, some hate it, personally I am in the in between camp and use it and try and maintain a regular regime and concentration taking the view is it is unlikely to do any harm and if it does some good, it’s definitely not bad!

Lastly if you want to get through to the winter and it’s only one tube, turn up some shallow taper plugs and blank that one off by knocking one in each end or even putting a long stud through them (don’t overtighten though). Worked on full size back in the day to get them to a point where they could plan the job proper ( check your boiler inspectors attitude first though).

Good luck,

Paul