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Member postings for Richard Parsons

Here is a list of all the postings Richard Parsons has made in our forums. Click on a thread name to jump to the thread.

Thread: An Orrary Help wanted
30/05/2012 13:53:06

Floating idlers are not needed to match the centres. if the input and output shafts are close enough the 'lay shaft' is put a different position on each plate. But you may have an idea about resetting the planet display. so i am thinking

Until you mentioned it I had not looked at Doni's clock., as it is before old "Copper-nickers", it is of only of passing interest. Any way i would need to employ 'Rent-a Goon' if I owned that much brass over here, I would also have to employ the local Rendoreseg to watch 'Rent-a-Goon' and Group 4 to watch the Rendorseg (the Bill).

Regards

Dick

30/05/2012 08:08:43

Michael I was aware of the Mercury drive system, where Mercenary drives Venus, Venus drives Earth etc.. One big problem with that system is that the errors accumulate. There is a secondary problem which is with the compound trains. In order to minimise the gear plates you have to consider changing the pitch (Module/D.P.) of each pair of gears in the train. I will try to explain supposing the Driver(1) and Driven (1) have a certain centre distance. Since Driven(1) is on a common shaft with Driver(2) and you wanted Driven(2) to run on the same shaft as Driver(1) then you would have to search all combinations of pitches in the catalogue. That is tedious and the program to do it is not nice and would occupy Old TOM (my computer – well it is a Toughly Obedient Moron many a long hour. I have designed a gear box which is much simpler and is based on 1 rotation of the Earth to drive each planet individually. It uses Mod 0.5 as this brings the whole thing into a box some 100mm overall. By doing this I can easily achieve errors of between 1.38E-5 and 4.92E-7 of the relevant planet’s ratio achieved with that required. I do that with only 4 gear wheels for each planet.

The only problem with it is that the individual planet shafts are 2mm wider than the previous shafts. So with the Mercury of 4mm OD the Saturn shaft will be 16mm OD and If Uranus and Neptune shafts were added the Neptune shaft would be 20mm OD. The reason for this is that there is one false shaft which does not rotate. This is to provide a drive for Earth’s Moon and if you wanted to you could use the same static shaft for the two moons of Mars.

If you wanted to you could add a second static shaft between Jupiter and Saturn for the major moons of those two planets (I am not going to unless asked as this would require another cart load of gears.) as for Uranus (27 Moons some of which run retrograde) and Neptune (13 known Moons, some also run retrograde –oink!). The gear boxes for that lot would be ‘ginormous’ and would probably need several horse power to drive them.

Rdgs

Dick

Edited By Richard Parsons on 30/05/2012 08:11:40

Thread: Gaskets
29/05/2012 10:30:17

The function of a gasket is to fill up the irregularities between the two surfaces being joined together. The flatter the surfaces are the better, coarse surfaces need thicker gaskets.

The problem is that the thicker caskets you use the stronger the material used has to be. This is to prevent the gasket from blowing out. In commercially made joints tend to have rather thick gaskets as fine finishes cost money.

Clive in your case I would use paper, a good quality ‘Bank paper’ if your finish is not too good or tracing paper or the old fashioned bog roll (Bronko or the like).

To make them I use a tiny ball-pein ‘tappy’ hammer, a sharp craft knife, a scribe to poke holes. I oil the surface well and stick the paper on it and lightly tap round the shape, hitting the paper down onto the edge of the item with just enough force to cut/thin down the paper. It is a skill/art which is easy to learn.

The thing is that thin paper gaskets, soaked in oil and squeezed firmly into the joint are extremely strong, cheap and easy to make. Once assembled they are not taken apart again for many years so the little effort to make them is well worth it

Rdgs

Dick

Thread: aluminium for gears
28/05/2012 12:03:30

Russell,

You are going into clock making ,good. The first thing you have to remember is FRICTION, friction, friction.

Forget all about the proper fits between gear wheels as given by calculating the PCDs etc fitting the gears is done by hand using a Geneva tool and make them a nice light fit. Back lash is never a problem. The pivots (shafts ) are a rattling good fit in their bearings . Remember clocks are very highly geared items. Ask yourself how many times will the thing beat in say 30 days and how many times the winding drum (or spring) will rotate in that time?

Aluminium can be intrinsically a very sticky metal, hard brasses used in clocks are not.

As a well known clock maker remarked “If it rattles it will run”.

Old John Harrison was a ‘downy old bird’. He knew the properties of lignum vitae. It is a very hard, dense and oily material. It was (and may be still is) used as part of the main of the thrust blocks which transfer the push of the propellers to the ships. Harrison’s lignum bearings make your aluminium seem like soft cheese and they are self lubricating.

Rdgs

Dick

Thread: An Orrary Help wanted
28/05/2012 09:00:39

Jeff

Thanks a lot for that idea. All I have to do now is to find somewhere and way of fitting it. The problem is I have not finished the ‘posh versions’ of the drawings yet. Most of the design consists of sketches and notes in my note book and ideas in my head.

For example the Planet Shafts each have a wall thicknesses of 1mm, (except for the Mercury shaft which is 4 mm solid) but as there are 7of them all told (one inside the other) at the point where they enter the gear box the overall diameter of the shafts is 16mm.

The best way seems to be in the intermediate gears as these can be made into individual modules pressed together using a Belden washer.

Rdgs

Dick

Thread: identification
27/05/2012 18:20:35

The bottom die can be changed easily, the problem is the top punch. How is it held in? Making new dies is easy enough and the little press is very usefull. It is quite light weight but you would find it usefull.

Rdgs

Dick

Thread: An Orrary Help wanted
27/05/2012 15:37:31

I now have the main parts of the Orrery designed. I have taken an executive decision to display only the Naked Eye planets, but I have left enough space to add Uranus and Neptune should the constructor want to.

At this point I need to describe some parts of the design. Firstly the machine is bases on the Earth Year which is 235.26 Earth Days. This is used to calculate the ‘Compound gear trains’ needed to give the planets their proper relative motion. Each planet is mounted on its own shaft of which there are 7. One is for each planet and one stationary shaft for the Earth/Moon combination. The shafts which are hollow fit and run inside each other with Saturn shaft being the Shortest and the planet nearest to the Sun – Mercury is the longest (it is also solid).

I have four problems which I hope someone can help solve. These are

  • In the normal Orrery the earth is represented by an oversized globe. Here the problem is should the earth rotate. If it does then it has to rotate 365.26 times for one rotation of the earth around the sun. As you can see if the Orrery were rotating at 10 RPM the earth would rotate at 3652.5 RPM. Should I make the Earth model rotate and would it matter if it did not? A second thought is that the Earth Must rotate once per year to demonstrate the summer/winter.
  • The planet shafts have a bearing at their top ends and rest on each other. To limit the height of the display these tops are to be ¼” (6.35mm) high. This would give a total height of about 45mm (just under 2&rdquo. I want to be able to reset the planet’s position. So I need to have some form of ‘friction clutch’. The planet carrying arms need to be robust so that when SWAMBO does her ‘dust removal’ operations things do not get bent. The bottom ends of the shafts have the final drive gear attached to it and in many cases there is not a lot of room there. Any one any ideas how to do it?
  • Should the distances between the planets be similar or should they be representative of reality. If you define the Earth orbit as 1 then Mercury is 0.39, Venus is 0.72, Mars is 1.524, Jupiter is 5.203, Saturn is 9.537. So Jupiter is over 5 times as far away from the sun as is the earth.
  • I have a problem with the representation of Saturn’s rings these are at 29 degrees to the ecliptic . Anyone any ideas how to make the thing?

Rdgs

Dick

Thread: Boiler and Metal Theft.
26/05/2012 11:06:15

Theft of metal over here n Hungary is so common and prevalent that people accept it as normal. Anything and everything goes. Overhead railway conductors from the railways vanish overnight. Power lines (and pylons) were taken from the building of a new grid supply. If a thunderstorm knocks out the local breakers the locals watch their power supply lines as they have a habit of vanishing.

This process was made worse by ‘oriental gents’ with suitcases full of` Euros. Almost everything went including wire fences. Scrap yards and Metal Stock Yards emptied over night. Old cars vanished and everything went. This is why 80-90% of lamp posts etc are in precast concrete.

In Hungary stuff can be out of the country in two to three hours However it takes some 23 – 30 hours to get to Europort and longer to get to Constanta,

That is why all my metal is 'under lock and key'

Rdgs

Dick

Thread: First post and lathe mounting
21/05/2012 17:44:53

 

I will agree with much of what Ketan has written. I regard all machines be they new or second hand as requiring ‘Commissioning’. That is dismantling (to a certain level) cleaning, fixing anything that is not too good and rebuilding with great care setting things up as you go.

On a lathe the size of the 7X12 is light and to my mind flimsy, so I would hunt out a nice bit of OLD (yes old) RSJ get it surfaced and bolt the lathe to that (with suitable adjusters in the mountings. You will have two problems with that as you will have to get the RSJ level before you mount up the lathe. You then level the lathe on the level RSJ. Remember with a ‘V’ bed lathe it the tops of the ‘V’s may be very crudly machined as they carry no load. I always level on the cross slide. This can also be doggy.

I will admit I missed something inside a new 6” lathe. It later got mixes up with the cross slide power feed and jammed it.  What I missed was a pink paper for a pestilence powder (or the 7th curse of Dr Fu Manchu on all round eyed foreign devils or even, dare I say, an advert for a local Pale Pink Peppermint Parlour in Pongping).

Finaly the first things I would make are two test/truing bars. Mine are very thick. Yours would need to have about 5/8” (16 MM) shafts and 1” (25.4MM) spools. My spools were stuck on with loktite. Will post pictures of them both ASAP

Edited By Richard Parsons on 21/05/2012 17:48:12

Thread: soba centre square
18/05/2012 17:55:51

Oil Magnet if I may suggest go to your local trading standards officer (if they are not in conference (aka down the pub). This is totally contrary to the Sale of Good Act as it is “NOT of merchantable quality and fit for the purposes for which it was intended” i.e. to mark the centre of a round item.

Mind you if they were anything like the lot where I used to live you could NEVER contact them!

rdgs

Dick

Thread: Newbie requesting info
17/05/2012 17:32:15

The third item looks like part of an internal micrometre. If you can find the rest of it which are extension rods. The length of each rod was the fully extension of the mike body different from the next shorter or longer. In maintenance you might find it used 2 or 3 times a year. It is one of those things when you need it belive you me 'you need it'

Bets Regards

Dick

Thread: An Orrary Help wanted
16/05/2012 14:20:47

Michael thanks. I was aware of some of the things you wrote about. I also came across another trick. This was to use gears of a different D.P./Module. If you wanted to make a say 6 to 1 reduction but keep the gears on the same shafts you set up say a 3 to 1 reduction whose output was input to a 2 to 1 pairing but the second set of gears were of a different D.P./Module to the 3 to 1. The second set of gears would have the same combined PCD as the first set. That can be quite fun to calculate. Actually I have done a lot of analysis and have come to a conclusion which simplifies everything. The basis of this is one rotation of the earth shaft.

Eric this is what I am going to do. Even if the gears were all of the same D.P./Module the cutters would cost an arm and a leg and you might well need the full set of 8. Hobbing would be different. I do not have a hobbing machine but I do not have one. I have challenged the electronic wizards to create a circuit which would allow me to drive a stepper motor at any programmable speed taken from my milling machine’s shaft. With this I could hob in my mill (or in the lathe). My gearbox is totally enclosed so that you can use the cheaper plastic cogs and no one will see them. If you want to show bright and shiny cogs then you can skeletonise the box.

David I afraid I have a dyslexic keyboard. The words Orrary and Orrery both show up as spolling mistooks. Actually you will find Google is very gentle on this and recourses are 10 a penny. In truth what I am doing is may be is ‘All me own work’ as I have turned things upside down.

16/05/2012 07:06:12

I would like to thank both Michael abd Bazyle for their advice. At the moment I am poking about with the problem of accuracy. I have decided to use 1 Earth year as the basis for the machine. The problem is how long a year should I use? (365 days, 365.25 days or 365.26 days.) My basic criteria is that I feel that the machine will be hand driven (you could have it steam driven if you want) but I feel that the manual drive should be about a 4 to 1 reduction. That is one turn of the handle should move the ‘earth’ through 90° (1/4 of its orbit). To show what would happen in say 10 years one would have to turn the handle 40 times. Is this too much? Ok Jupiter will have made almost ½ of its orbit and Saturn 1/3rd of its. Uranus will have moved under 1/8th of its orbit and Neptune just less than1/16th of its.

How much error would be tolerable? One thing I am trying to avoid is the need for compound gear trains (if I can).

I also intend to leave enough space in the gear box(es) for someone to be able to add more planets without having to do a rebuild. The problem with mechanical things unlike software is that to add new facilities you sometimes have to totally rebuild previously made components. If the original designer has made allowances for this the person upgrading the design has to stay within the original design philosophy. So there is with mechanical things a great difficulty for purely ‘free flight’ development.

Michael

I was attracted to the pre Copernicus model of the universe but I feel that this would be an anachronism and would only be of interest to a historian. There was at least one of these machines. Have a look at the ‘clock of Richard of Wallingford’. This was at St Albans Cathedral it is a modern replacement. There is also the ‘Great Clock of Olomouc’ in the Czech Republic.

Regds

Dick

Thread: Open Source models
16/05/2012 06:24:17

The problem with mechanical things unlike software is that to add new facilities you sometimes have to totally redesign and rebuild previously made components. If the original designer has made allowances for this the person upgrading the design has to stay within the original design philosophy. So there is with mechanical things a great difficulty for purely ‘free flight’ development

Rdgs
Dick

Thread: An Orrary Help wanted
15/05/2012 08:14:37

 

I could do with a little bit of advice here. I am redesigning my Orrary which a want to write up either for publication or if the ‘Head Hitter’ (David) wants it as part of his ‘open project’

My problem is how far should I go with it? I have 3 ideas which are to represent the movements of the planets as follows:

  • The 4 inner planets (Mercury, Venus, Earth (and its moon) and Mars.
  • The Six naked eye planets which are the 4 inner planets plus Jupiter and Saturn
  • All the Major planets which are the six naked eye planets and Uranus and Neptune I am not dealing with Pluto.

My question is which of those three choices should I make? After all the contraption is one that ‘SWAMBO’ could trot out to show here friends how cleaver her ‘HITS’ is. Oh yes HITS is “Him in the Shed’.

I know at the end of the day the choice will depend on the gears or as I prefer tp call them the ‘coggery’.

Rdgs

Dick

Edited By Richard Parsons on 15/05/2012 08:15:38

Thread: I/C Topics returns - Not off to a good start
14/05/2012 16:04:42

Back in the U.K. I could never travel on the London Underground. There was a notice which said the 'Dogs must be carried on the escalators'. I did not own one.

Rdgs

Dick

p.s. They used to say 'Nothing acts faster than Anadin'. If I had a headache it would last for a long time so i hate to think what would have happened if I had taken Anadin.

Thread: Marking metals
14/05/2012 11:57:34

Mike you are nearly correct. My Dad had one. It was called an electric pencil. Inside there was an electro-magnet which acted on a spring. This has a clamp for the electrode at one end and the other was connected to the coil of the electro-magnet and thence to a 12 Volt transformer. The other side of the 12 volt transformer was connected to the work piece.

When the point of the electrode touched the work the circuit was completed and the electrode point was withdrawn with a little spark. The circuit was then broken so the point fell onto the work piece and so on.

The device was like a large pen acting not back into the machine like the Burgess unit but at a right angle to the pen handle. It vibrated yeas but not with any force.

The old man uses to use a scrap of 1/16” gas welding rod ground to a point as the electrode.

I think it had a single coil wound parallel to the spring and the whole thing was about ¾” to 1” at its maximum diameter and some where about 9” long. That is all I can remember about it. I think it sort of vanished about 1950.

Why not make your self one.

Regards

Dick

Thread: Not fit for purpose
14/05/2012 06:42:35

Ah new software! These days software is not 'released it just 'escapes'!

Rdgs

Dick

Thread: After pickle wash
14/05/2012 06:34:25

It could be. Try a first rinse with deionised water - the stuff that is used in irons.

Rdgs

Dick

Edited By Richard Parsons on 14/05/2012 06:34:38

Thread: Open Source models
14/05/2012 04:30:22

 

I like the idea, but I have a problem is the question of what are the constraints on tooling? To date it has been suggested that a 7X12 (3 1/2X12 in the U.K.) lathe. Any milling and drilling needed must be do-able in the lathe. If that is the case we would have to describe how to make any special tools needed as a series of sub projects.

What sort of model? In my opinion it must be the following

  1. A ‘quick and dirty’ thing. This is to give quick results.
  2. It will work first time even with ‘rattling good fits’.
  3. It must teach the beginner the ‘how to do it’ and later in the project ‘how to figure out how to do it’.
  4. No castings (but these could be ‘optional extras&rsquo.
  5. It must ‘do something’ not just chug round.
  6. It may have optional (cheap) bought in parts. That is you can buy them or make them.
  7. It should use ‘stock materials’ which to me means working in Metric. But we should always remind people of the ‘magic number’ 25.4.
  8. I would suggest a limit of no more than 48 parts.

So what is it to be? I have few suggestions (which I will draw if wanted). These would be: -

  1. A ‘contraption’ which seems to defy gravity (8 to 9 parts).
  2. A form of ‘Fergusons paradox’ machine. I do not really like that one.
  3. An Orrary which could come in one of two forms. The first is type which shows the position of the moon vis-à-vis the earth which also uses a form of ‘Fergusons paradox’. Secondly the type is one which shows the rotation of the ‘4 inner planets and (our moon)’. In both cases one could buy in the gear wheels.
  4. A thumb motor which drives a little generator with a lamp or an LED, or a little compressor which blows a whistle.
  5. One of Heron of Alexandria little ‘applied miracles’. I like the ‘programmable cart’ and the ‘glutton’s chalice’ which is messy but fun.

All of these are what I would call ‘Dinner table’ items which ‘SWAMBO’ would be glad to drag out to show how cleaver her ‘HITS’ is. At the moment I think 5 suggestions are enough from me, except to say that a locomotive to my mind too large a project for a beginner as it would take them too long to get a result.

Who or what is ‘HITS’ well it is “Him in the Shed”.

Rdgs

Dick

Edited By Richard Parsons on 14/05/2012 04:32:57

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