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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: How do I fit a rope piston ring to a beam engine condenser?
06/02/2012 05:42:19
Andy I fear that you will have to learn the secrets of making ‘Square Sennit (or Sinnet)’. Hmm! From memory its making involved many strange oaths, ‘sippers’ of ‘Jamaican Nectar’ (real rum the nearest thing is Woods usual disclaimer) and a baccy pipe.

Two stands of Sisal, Hemp or Manila are whipped at each end and are then ‘middled’ into 4 strands and then plaited just like normal Sennit (or Sinnet) except that the right most strand is tucked ‘round the back’ and over the left most strand. The result is an almost square shaped plait. Square.

I have found two reasonable videos. The first one http://www.youtube.com/watch?v=1lWFn3iyH0I used 4 strands or rather two strands middled. The second one http://www.youtube.com/watch?v=fCcMBl6ecSc uses a single strand and is complicated. For your job I would use the first 4 strand method. There is an excellent diagram at http://home.tiscali.nl/knotsandknottying/knots7.htm#vierkanteplatting4streng .Have a go with some old boot laces first
The strange oaths occurred when the man noticed he had made a ‘Goof’ and had to undo his work.
Square Sennit (or Sinnet)’ was not only used for decorative work but for gaskets, joint washers, piston ‘rings’ and other seals. When stuffed into the place where it is going any slackness in the weave is taken up, and if you are cunning it can be woven on the lines of a ‘Turks Head’. This would be woven loose and then put in place and then tightened up.
Good luck
Dick
Thread: Outstanding Detail Modelling
05/02/2012 17:26:56
I am afraid that I started with the cardboard Micromodels. I could buy a whole packet for 1/3d and that left me 3d to spend on other things. No sweeties they were on ‘ration’ in those days.
Rdgs
Dick
Thread: Machining Crankshaft
05/02/2012 17:22:36
John do a search on this site for V12 as the keyword. Pick Mr Worland’s post and follow the link. At about 1minute in you will see just how the builder did it more than once. You see the the tools used etc.
Good Luck
Dick
Thread: Is this scrap?
04/02/2012 18:11:04
No get a little "3 square" emery stone or a diamond file and one day start to sharpen it. It will do a 'turn' when you need it.
Good practice
Rdgs
Dick
Thread: Stirling Engine development
03/02/2012 11:50:41
Using Stirling engines as generators was an idea of Phillips of Eindhoven. In the 30s and 40s they developed the Rhombic drive engine which was intended to replace the Low Tension batteries in Non Mains powered radios. The fuel was any combustible liquid like lamp oil (which would have been used to light the Sahib’s bungalow).
The project was canned because the transistor required a fraction of the power required by the Thermionic valve.
Rdgs
Dick
 
Thread: Recessed grinding wheel
02/02/2012 13:51:03
David have a look at Arc Euro Trade (Usual Disclaimer) I have seen their advert somewhere. I bought one of their dianond wheels and it grinds well
Rdgs
Dick

Edited By Richard Parsons on 02/02/2012 13:51:53

Thread: boiler
02/02/2012 11:08:43
Jon
If the only problem are the two longitudinal stays that is not too bad. The original is copper and was ‘Silver’ (hard) soldered. As these stays were under tension I would make two ‘Top Hat’ bushes for each stay to push in from the outside. I would probably had them threaded internally to fit the stay. Clean up the boiler area well where they where they would be fitted and silver them in using the lowest melting point Silver’ (hard) soldered spelter. Do not forget to clean flux everything before fitting.
Rdgs
Dick
Thread: Drilling small holes
01/02/2012 10:03:41
Taper reaming, are you using ‘Clock Makers Broaches’? These are normally hand tools. I have two sets. The 6-sided type for getting the hole close to size. I then use round smooth burnishing reamers to finish the hole.
Yes you can use ball bearings especially on those parts of the ‘Going Train’ where the ‘power levels’ are high. As the gearing ratio’s increase then ball/needle roller races are not advisable. You can get very low friction inserts, but in have never used them on clocks. I was using them on my tide computer where they worked well. That was until I received a ‘tribal visit’. The ‘Skilled Man’ dumped a large lump of a tractor engine on my instrument bench. As a result of my protest –he had crushed my multi-meter and the mechanical tide computer and other odds and ends. He then threw all the broken stuff into the barley field opposite –enough!
I normally drill my plates with my Startrite Mercuary pillar drill for the pivots or in my milling machine (using co-ordinate drilling) for the support pillars. I always use a slab of block board to drill on. This stuff is reasonably accurate.
Using the Archimedian drill you will find that with very small drills they will automatically become very close to the vertical. I have read that Cherry Hill uses them to spot the centres of holes to be drilled.
If you are drilling deep holes I have a rule of pecking which seems to work it is that the peck should be no deeper than 1 ½ time the drill diameter. I have drilled 1/16” holes 3.2” deep. It was slow work but successful.
Rdgs
Dick
31/01/2012 18:22:24
Rob. Why not do as the old’uns (Graham, Harrison, Mudd, Breguet and the rest would have done. Do it by hand. Use a little Archmeanian drill and take your time.
If you are drilling by machine lock both plates together and clamp them down well. Use a high speed and take it slow. Pin chucks are not accurate they are for hand use. Get an eclipse 160 Pin Chuck this is what I use.
Do not get too worried about deadly accuracy on the hole size. You will have to broach it out to get the clock to run. Old clock makers have a saying it “If rattles it will run”.
Rdgs
Dick
Thread: Milling - difficult to gauge exact cut
29/01/2012 17:36:33
The core of the problem lies in the use of the vertical milling machines for cutting narrow slots. It is made easier by using ‘Slot Drills. These are (generally) two cutting faces on each cutter where the centres at the ends are not centralised.
The real problem is caused by the fact that one side of the cutter is performing a ‘Conventional Milling Cut’ and the opposite side is performing a ‘Climb Milling Cut’. This gives you three problems which are:-
· With a thin Slot drill the drill will be bent towards the ‘Conventional Milling Cut’ side of the slot.
· With a thicker slot drill the cutting forces will move the bearings (and the quill) towards the ‘Conventional Milling Cut’ side of the slot.
· In both cases there will be problems with any backlash or looseness in the moving slide.
You can prove this for yourself by taking two or three shallow cuts followed by a deeper one and inspecting the results by looking down the sides of the slot.
This is why if I have to machine a slot in something I try to use a slotting saw, a Woodruff cutter or something similar. It is one very good reason why I still keep my vertical slide in good condition and saw carrier for my lathe. It is also why I want to ‘drop my hooks’ on a small Horizontal mill, a Shaper or a Box plainer.
I have looked at my vertical mill many and oft to see if I could make a small horizontal converter. I can design a converter easily BUT the problem is fixing it to the machine so that it is always parallel to the movement of the table and deals with the difficulties of off centred cutting loads.
Rdgs
Dick
Thread: Manky External Threads
26/01/2012 17:50:47
Hi Allan cutting an external thread in the lathe with a die can and is often fraught. I always (where I can) set up the gear box and turn the thread down to at least 50% of the finished diameter of the thread and finish it with at least two passes with a die. In the first pass I set the split die open (that is what the ‘centre’ screw is for). I then try it with the nut (or whatever). I then let the die close a bit –may be a turn of the centre screw or less- and repeat the process. A bit of a fag, but it is worth it.

By the way 0BA is 6mm diameter by 1mm pitch. At a pinch you can get away with 25 tpi and by using an ISO metric tool to cut the 50% thread depth.
Rdgs
Dick
Thread: Another broken tap thread
26/01/2012 10:21:05
John There many ways of digging out broken taps. But before I begin are your holes ‘through’ or ‘blind holes’?
Method 1 The chemical method. This depends on the fact that hardened steels are more readily attacked by chemicals than mild steel. I generally use this method for taps smaller than 3.2 mm. Get hold of a solution of Ferric Chloride (the stuff used to etch Printed circuit boards). Clean out the cutting oil with isopropanol then drip in the Ferric Chloride. If it is a open ended hole stop up the bottom with something. This method is slow.
Method 2 Make a hollow cutter. As you are using 6mm I would make the hole down the centre 6.32 mm (1/4” with an outside diameter 7.5mm. Now cut out a larger hole. Plug the hole In 15mm I would silver solder in the plug – drill and re-tap-
Method 3 This is similar to method 4 Make a short-ish stub of some tough old steel. Drill a shallow-ish hole in one end say 3/8” deep. This will have the same diameter as the core of the tap. Now file 2, 3 or 4 short prongs (The number you cut will depend on the number of lands in the tap). It is a good idea to make them fit closely into the lands of the tap. They do not want to be more than ¼” long. Try to unscrew the tap.
Method 4 This work on larger sizes of taps 6mm up. Buy or make a tap extractor. You could look on ‘Flea bay’ for them you want a 6mm. I bought a few at a car boot sale – the geezer flogging them did not know what they were and I did not tell him.
Method 5 get yourself a thin rat tailed diamond file (I think AC Euro do them as I bought a set from them) use one to file away part of the core of the tap.
Method 6 The ultimate make a new pad.
The picture shows a selection of tap extractors in the top left is a 3/8” tap in the 3/8”extractor. In the bottom left is one in pieces –it also has a bit missing –the sleeve- I will make one after I have made a round tuit (or bought one)

Oh the smallest is for 1/8" (3,2mm - 5BA)
.
David just looking at them I have figured out how to make them (Not the tuits). Do you want a short article?
Thread: Rob Roy
22/01/2012 14:38:47
Can anyone help me? I am designing a machine (if I can get the metal). It is a sort of shaper. My problem is that the machine I want is quite small, but if I am making it and writing it up for others I may as well make it a bit larger so that others will also find it useful.
What I want to know is how large would the casting be for the inside cylinders of a 5” gauge loco?
Rgds
Dick Parsons
Thread: MEW 186, Best ever issue
20/01/2012 12:47:16
There are three types of workshop
Type 1 All manual
Type 2 Mainly manual, but which have some bits of electronics. This is like mine I use electronic measuring gear.
Type 3 the full blown CNC stuff which I cannot afford. In my case I am to old to learn to use.
The problem is balance between these three types of shop.
I would be quite happy to dig out my soldering iron and build small item which did one thing and had one specific use. I know it can be done. I have the basic logic written down, but everyone who could help me with a simple electronics design wants not only to add bells, gongs and whistles but drums as well. I want it to do one thing and one thing only. I do not even want to reverse/joggle.
I looked at the item by Tony Jeffree which I have known about for some time. It is very close to what I want BUT it can do so much more. I do not want to cut threads electronically. Two of my lathes can do exactly this without being modified. The third is a watchmaker’s lathe. In most cases I can do this by moving a couple of leavers and in the extreme I can do it by simply changing a few cogs in the box. I can turn tapers no problem.

It is like the business of speed controllers. My belt changing/gear changing is adequate, simple and easy to fix when it goes wrong. Like many mechanical systems it gives you warnings beforehand if you heed them. The first thing you know with electronic stuff either the awful smell or it just don’t work. Nuff said!
Ok call me a flat earth-ist or a Luddite. If I am doing repetition work I will make jigs and fixtures to help me. If I can only machine the thing using CNC then I probably will not tackle the project. I seem to remember someone writing a tale where the old fashioned ‘knife and fork’ methods were superior to the CNC stuff.

Oh what do I want from the electronic wizards? I want to be able to measure the rotational speed of a shaft and get another shaft to rotate at an exact speed slower than the main shaft. I need to be able to change the ratios of the shafts at will, but the ratios are always a whole number. I want to do this as I cannot fit a takeoff gear to the main shaft and the two shafts are at right angles (or worse) to each other. What is it for? Gear hobbing in my vertical mill.
My machines make things and that is what I enjoy doing.
Rdgs
Dick
Thread: Painting blue styrofoam
20/01/2012 11:40:14
Hi all
Try this tick, Mix your paint/varnish with French chalk. Make it a thick-ish mixture. Slap iy onto the surface and let it dry for a few days then sand it.
Rdgs
Dick
Thread: Milling Course
16/01/2012 17:52:10
Woolfie Hi there
For years many years I have used this sort of thing. They take about 4 to 5 minutes to make. Just a few strokes of a file. They are dirt cheap so if they get messed up no problem. They come in any length you care to name and the raw materials can be bought in ‘B’ and ‘Queue up a long time to pay’
Good luck
Dick.

Thread: Metal thefts
16/01/2012 08:49:13
Early December last year the local supermarket was having its power supply re-organised. This meant isolating the high tension supply at the main substation. 8 hours later they tried to switch it back on, but someone had removed the overhead cables from the pylons. These were replaced next day, but the transformer in the local substation had ‘vanished’. They are due to replace the smaller stand by transformer in February. I wonder what else will go this time.

The local police said that they think the cables were in Serbia before anyone knew they had gone.
Thread: 9x20 Lathe Parts
13/01/2012 17:21:56
Turning the cross slide/the feed screw nut the wrong way is very common on watch maker’s lathes. It is a damned nuisance if you have been using a ‘Normal Lathe’ for the past few weeks
Dick
Thread: Wheel Cuting thin tooth?
08/01/2012 08:57:28
There is one thing we have not looked at yet. It is the cutter.

Peter I presume that you are cutting an involute wheels Module 0.75.
Since you are not using a Hob but a single tooth cutter you need to be aware that for each Module (or D.P.) there are 8 cutters (plus another 7 for high accuracy). These cutters are for different numbers of teeth. For 115 teeth you would need a No 2 cutter (55 to 134 teeth) or for high accuracy a No 1 ½ cutter (80 to 134 teeth).
Which one have you got? Thorntons are an outfit of very high repute but mistakes do occur. If it is a No2 cutter it might be worth you getting contact with them.
Rdgs
Dick
07/01/2012 17:54:04
Martin - Peter wrote “The Direct indexing from a plate on the end of the spindle, made the plate last year using a rotary table, drilled twice so that we could check for errors”.

That is where the Errors crept in. sure the plate has 115 holes in it and they are evenly spaced but each hole is a little bit wrong in its position. I will bet that the distance between the first and last hole is wrong. But there are 115 of them.

Oh a golden rule is ‘Never turn it backwards or if you must turn it far enough to take up the backlash!
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