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Member postings for Paul Kemp

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

Thread: Need a lot of help from you good people
19/08/2019 22:49:19

My 040 battery loco runs fine on its C5 motor. Used to pull my kids round the club track and also a car load of kids up and down my portable track at fetes all afternoon without missing a beat on an old Capri car battery!


Thread: Superheat or not?
17/08/2019 21:13:52


i have been on a full size loco fitted with superheaters that had water carry over through the level being too high and that ran away or rather carried on when the regulator was closed. Solution was to wind into mid gear and it stopped but there was still pressure on the steam chest so yes it can happen. Not sure on a miniature it would run very far though, as you say the volumes are small but still in proportion I guess. Any driver that couldn't deal with this is not much of a driver though unless it was pole reverse in which case he may need a bit of help to pull it back to mid gear from the fireman!


Thread: Regulator improvements
16/07/2019 22:07:45

Is the boiler clean? As previously mentioned what is the water quality? Carry over is not unheard of as steam demand increases. If you imagine the rate you are taking steam off the water if the demand is high then you get vigorous bubbles at the water / steam interface and the more steam you need the more likely it will pick up water with it. If you search spirax sarco on utube you will find some very good videos taken inside an industrial boiler of what happens. Keeping the boiler clean and the TDS down may be all you need.


Thread: Electric Cars
11/07/2019 20:31:59
Posted by Barnaby Wilde on 11/07/2019 20:19:47:

Anyone who still has their 'wits' about them can work out that EV's do not yet win the economic argument over an ICE equivalent. If the environmental aspect cancels that out for you then I'm sorry to say that you probably misunderstand the true environmental impact of anything & choose to believe what you believe to be true.

I also listened to the recent radio 4 slot on EV's with great interest, it got very many things very horribly wrong.

Did you know that the EV equivalent of an ICE vehicle costs substantially more to insure??? Of course you did, after all you still have your 'wits' about you & you believe everything that the BBC says . . .

I have £100 to donate to the charity of your choice, to anyone who can come up with the real reason that the insurance underwriters consider an EV to be a greater risk than it's ICE equivalent . . . .

I would guess it's little about the risk of actually making a claim and more about the cost of any claim that is made. Given the disparity in purchase price between an ICEV and EV the financial risk of claim is increased as it seems most vehicles can be written off these days for a moderate sized dent! Writing off an EV is therefore going to cost substantially more.


Thread: Best instructions
05/07/2019 21:37:00

Commercial technical manuals these days are so full of caveats and advise to use gloves, boots, hard hats, not to drink the oil, wear ear defenders etc etc that extracting the actual information you really need is next to impossible! Sadly the expectation now is that the documentation will be used by a child, the office secretary or apprentice and not by a qualified technician that should already be aware of the safety considerations.


Thread: Part built Allchin 1.5 inch
05/07/2019 21:27:08

Hi Derek,

Good to see you are still pushing ahead. Traditionally model injectors seem to be rated in fl oz per minute. So in choosing a suitable one look at the volume of water in your boiler at running level and compare to the volume delivered per minute of any proposed injector.

General comment I would make is a lot of models seem to have injectors that are over capacity and will raise the level in the glass from empty to full in short order, some within a minute! While that may be desirable for some it is not very kind to the boiler as a large quantity of cool water squirted in by the injector knocks the pressure back which puts quite a significant temperature / pressure stress cycle on the boiler. It is kinder and more efficient to have an injector with a lower delivery that can be left on for longer if needed but if used regularly for smaller amounts you can control the pressure water level much better and do not have such wild fluctuations.

Others may well have different opinions but I have never come across a full size boiler yet that you can take from the bottom to the top of the glass in a minute or two! Generally the injectors are matched to balance or slightly exceed the water consumption at full load. Often on railway loco's you have two injectors, one having a higher delivery than the other to better match operating conditions.


Thread: Microns ...
05/07/2019 00:22:01


Very nice I am sure and a fantastic piece of kit but I am with John on this one and such an instrument for what I do has no place in my shed lol.

Building a half size version of an early 1900's traction engine and following the prototype where limits and fits were to the closest 5 thou or 1/16" on the cast gears I have no need or desire to work to the tolerances capable of being measured by this!

A common mistake by new builders of steam engines is to make everything to too close a fit and consequently they are so tight they won't run! I have a 5" gauge loco built by an early mentor of mine now long sadly gone which is now 58 years old, on its 3rd boiler and has done 1000's of real miles over the years giving rides on a portable track. Apart from the boiler replacements it has had one set of piston valves and a couple of bushes in the motion to my knowledge and that's it. Yes it clanks and bangs a bit (as does a full size if you get the chance to ride one) but it still goes like the proverbial rocket and I consider it now properly run in. Everything on it was measured with an old manual Moore and Wright vernier and I think it's service record shows that was plenty good enough.

Dont get me wrong, as a time served fitter turner I can make things fit adequately for purpose but I am not going to spend time working to limits that are not required for a decent practical end result. Half a thou is as small as I practically need to measure.


Thread: Omnimill 00 Opinions
30/06/2019 15:46:59


As always the amount you can plough off not only depends on the machine but also the set up / arrangement for work holding. With a lump of steel in the vice I generally take between 0.030" and 0.050" cuts with a 2" 4 insert face mill in the vertical spindle, if not clamped quite so rigidly then less. Earlier this year I had to cut a 3/4" slot through cast iron again about 0.050" bites with a 3/4" end mill, probably would have taken twice that easilly but I wasn't in a rush, it was clamped to a large angle plate and didn't want to risk screwing up the casting to find out. I have also used up to 1" dia drills in the quill. I cut the full set of gears for my half size traction engine (cast iron blanks) 4DP so 0.530" (from memory) tooth depth in one pass, biggest gear was @19" diameter on the horizontal spindle with no particular issues, just a conservative feed rate. I don't think I would take 1/4" cuts with a slab mill, it's an "industrial" machine but a relatively small one!. Others have questioned rigidity of the vertical head and made additional support brackets to tie it to the horizontal over arm but to date I have had no reason to need to do that. Attraction for me is the versatility, you can reposition the vertical spindle to get anywhere over the table and being able to tilt it made drilling the steam ports in the cylinder casting a doddle.


Thread: RequiredOutside Diameter to Cut 5/16 BSF Thread
23/06/2019 14:26:02


All above answers correct. Some other considerations for you though depending on how you plan to cut the thread. If you measure commercially made fastenings depending on the tolerance and thread engagement you will find they have a major diameter slightly smaller than nominal.

if you are going to screw cut then starting with the full nominal is a good idea as your depth will be related to that. If you are going to use a split circular die then being a few thou under the nominal won't hurt as there will be a degree of extrusion in the die cutting process and it will be easier to cut.


Thread: Steam whistle desigh
20/06/2019 21:03:32


I struggled big time to make the whistle that came with the bits for my 4" RP whistle! Read loads of stuff on net which to be honest wasn't very helpful or consistent! Edge of the bell on mine is square and ended up with an annular gap of less than 5 thou. The gap seemed to be the critical bit! Profile of the edge of the bell and vertical height of bell above the base much less important. A decent deep tone depends on size of the bell.


Thread: Lathe Speed - What am I missing out on?
18/06/2019 21:19:39
Posted by Andrew Johnston on 18/06/2019 20:35:54:
Posted by Blue Heeler on 17/06/2019 23:24:38:

I use HSS and carbide insert tooling, turn steel, brass, copper, cast iron, aluminium, plastic and get a mirror finish on all materials.

Good grief, I've obviously still got a lot to learn then. embarrassed First thing is to stop fiddling with the spindle speed knobs. smile


Me too Andrew! I have only been doing this metal bashing lark for 45 years and I still can't get a mirror finish on everything I make. I must be using the wrong tooling or not grinding it proper.


Thread: Is this cheap type of VFD worth buying?
18/06/2019 21:02:30

Well I have two hynyaung (or however you spell it) Chinese inverters running my mill for about 14 months now and they have been absolutely fine, no complaints whatsoever. The set up wasn't difficult, plenty of info available on the web to assist in 'interpreting' the manual. There was one parameter that was troublesome but with some excellent support from here I managed to sort it without any drama. For my application it was around 1/3 of the cost of using the UK based suppliers to achieve the same result going this way and as the total cost at the time was a barrier to get the machine running the longevity wasn't a major consideration. For the work the machine has done I don't consider they owe me much and even if they pack up now (which they probably will now I have written this!) I won't be overly upset. As things stand I wouldn't hesitate to go the same route again. The only caution I would sound is buying direct from China and having them ship from there, my first attempt at that didn't go well! On the second try I used a UK based seller and they were with me in three days, cost me a little more but worth it to save a 5 week sea freight delivery and import duty etc. Overall very happy!


Thread: Cheap Carbide Lathe Tools
17/06/2019 23:35:11

Well I use em, I don't have any issues. Have a set of 16mm that I use on the big lathes I have access too (Edgewick, Holbrook and Harrison), some 8mm ones I use on the hobbymat at home and occasionally on the myford. Out of the 16mm set I don't think there is any I haven't used although perhaps not for their intended purpose! Ie the parting tool has been ground into a long reach threading tool and a couple of the others 'butchered' to strange shapes to suit difficult access areas on some iron castings. That said I also use HSS and indexable tips on all the machines. I have a 1" square long boring bar (home made) that uses round HSS bits. Tend to use whatever will work the best for whatever job is being done or whatever is the most cost effective way of getting decent cuts. Can't really understand why people get hung up on one particular tooling type, they all have advantages and disadvantages, why limit yourself? I also save the blunt or chipped indexable tips and if I need something obscure braze em on to a bit of bar and free hand grind them, handy for custom bars for the boring heads. Sometimes I will rough out with a tipped tool and then finish with HSS. Only indexable tips I have never used I think are screw cutting tips, mostly I grind them from HSS although I do have and have used some brazed tip ones. I don't need to cut any micron perfect threads so my methods suit what I need to do.


Thread: traction engine pump
15/06/2019 13:51:03


You say the pump works off the engine when dunked in a shallow container. That implies the suction fitting on the pump body is direct in the water? When operating the pump like that does it develop any pressure on the outlet or are you just observing a little water being discharged? If you put your finger over the outlet when testing off the engine you can see if it is developing any pressure. You can test the delivery valve by connecting an air line (carefully) to the outlet. If the valve is good there will be no movement of the ram. You can test the suction valve by blocking or plugging the outlet, you should be able to pull the ram out on the suction stroke but not push it back in on the delivery stroke. If you can push the ram in you need to check if either the ram seal is leaking or if it is returning past the suction valve ie the suction valve is leaking. That will confirm the pump is good. Last thought is the pump of a type that has an integral bypass valve fitted in the body casting. If so as Jason said is the valve in the correct position? Picture of the pump might help. Good luck.


Thread: Class 22 Diesel (next project)
12/06/2019 21:34:26


Personally I think you are over thinking the situation between pulley and bearing. Firstly the relative rotational speeds are pretty low as are the loadings. If the shaft is to be a soft (say mild steel) material then using hardened washers is likely to have them cut a groove in the shaft over time! Oilite is a bearing material and no reason to suppose that in this 'thrust' application it will be any less efficient than in the normal radial condition. Many thrust bearings are plain bronze with oil lubrication, oilite is a similar but 'self lubricating' material. Your PTFE washer is probably the kindest solution to shaft, bearing and pulley if you really want to control the axial location of the assembly. Lastly I doubt the loco will travel the distance of London to Edinburgh so whatever you do is unlikely to wear catastrophically.

is the TE on the back burner now?


Thread: Rover V8 drilling valve guides
12/06/2019 21:18:43

I would assume it's to preserve the fit. Every time you press something out the hole gets a teeny bit bigger. Drilling them out first reduces the bulk of material and relaxes the strength of the fit hence reducing the growth of the hole and preserving the original tolerance.


Thread: boiler parts
08/06/2019 19:13:27

Through a hole and pipe extension off the side, not yet drilled and fitted! Looks like it was left once the turning was completed and never finished!


08/06/2019 18:46:18

Difficult to be sure with the size of the picture but it looks like it should be a captive blow down valve. Ball goes in the shroud at the end of the spindle which gets forced onto the seat in the body when the spindle is tightened. Back nut is to stop you screwing it all the way out!


Thread: Motorcycle 'blipping'...
03/06/2019 19:28:44
Posted by Chris Evans 6 on 03/06/2019 18:33:26:

I've ridden bikes for 55 years and still do. I think Haggerleases comments have very little grounds for reality. I and most others I know ride sensibly and with a desire to ride again tomorrow.

Try driving London bound on the M2 / A2 in the morning and the opposite way in the evening! I unfortunately have to do this fairly regularly and having ridden bikes myself I still have palpitations watching the antics, get on centre white line between lanes, open throttle and try to weave between anything that may be in your path - it's worse on the multi lane sections if you are in a car at 60 (you can rarely get to 70 and more often 15 is optimistic!) but at 60 you can have the pleasure of being both undertaken and overtaken by bikes on either side between the adjacent cars - not even waiting for a gap! I have had my mirror clouted twice in the last fortnight and saw one come to grief. Maybe things are different in your neck of the woods! I rode bikes for many years and did a few track days but the way bikers behave now scares me!


Thread: Part built Allchin 1.5 inch
31/05/2019 00:15:09


Afraid I don't know the detail of the Alchin diff as have never built one but when making the diff on my LS I left the centre boss of the diff housing (both sides) over length from the figure quoted on the drawing. I then set it up in the lathe first one way and then the other and gently faced it back to get a nice engagement with a bit of clearance / backlash on both crown wheels to the pinions. Worth mentioning all gears in the diff on my 6" LS are cast gears (as many full size engines were) so they are not as precise as machined gears!

As I am guessing on the Alchin I would say you are on the right track with shims. Ideally you want a little bit of backlash in the diff for smooth running.


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