Member postings for Paul Kemp

Probably! Unless it is a brand new never been steamed example that is clean. You may get away with it then if you have a torch that can localise the heat mainly to the area of the bush.

Paul.

Derek,

Ooops! Sadly a hazard of the hobby. I don't think I would bother with another casting but get a lump of cored bronze of the right proportions and chew it out of that. You can get cored bronze in various O/D - I/D combinations and it will almost certainly be cheaper than a casting from a model supplier. I have bought from metals4u in the past, they sell by the inch. Doubtless there are other sources. I think I would bore the block first and then turn the liner to suit, needs to be a good fit so steam can't leak from the anulus, you probably need around a thou to thou and a half interference fit on that size.

Paul.

Derek,

Just a thought, when you set it up try and clock it to the saddle radius so you ensure the bore is parallel to the boiler and square to the crank. When I did my 6" I had the luxury of using a horizontal borer so I was able to machine the saddle radius and the bore at the same setting guaranteeing they were parallel. We had the problem with my mate's full size Avelling which had a new boiler and the boiler maker didn't get the cylinder seating rivetted on true - lots of fun trying to correct that! Good luck, you will be pleased you did it when you have done it lol.

Paul.

Derek,

Given the 'non critical' nature of the annulus if you used Jason's 4 lobed method you could always use a small rotary burr carefully and gently after to clean down the high spots if you are concerned re any reduction of CSA.

Paul.

Ben,

I sent you a PM.

Paul.

Derek,

This is a bit like watchmaking to me with the size of the cylinder! However considering that the actual diameter of the annulus is not critical within a few thou and the surface finish is also relatively unimportant your main considerations are making it big enough to get sufficient steam flow without conflicting with the drillings. If you don't have a boring head you could in a rough and ready way replicate Jason's suggestion with careful use of a four jaw chuck. If you mount a decent square shank boring bar in the chuck you can advance it with careful adjustment of two opposing jaws on the chuck. As I said a bit rough and ready but if you are careful and take it slow you can use Jason's suggested method of doing the cut and advance the tool in the jaws. There is another way of making a boring bar with a tool you can advance with a tapered screw in from the end under the toolbit but that would be more difficult with the small size of the hole. Half the challange (and fun) of making these things is finding a way to do it with whatever resources you have. I have had a bit to do with in situ machining to repair large Diesel engines and line boring of bushes on ships and steam engines in the past and it's surprising the results you can get with some really Heath Robinson equipment in terms of accuracy and finish!

Paul.

Ben,

It may not be an insurmountable problem. If the boiler is of an established design and there is evidence of construction then an inspector under the code could examine it and carry out a 2xwp shell test and move forward from there. His other option could be to accept the manufacturer shell test and certificate it for a working pressure of half the value of the manufacturer shell test certificate. Both these would be dependent on the boiler being CE marked, if it's not CE marked the code specifically prohibits him from testing it at all. The construction evidence he would be looking for would be material certificates and evidence of welder competence in the case of a steel or TIG welded copper boiler (welder certificate may not be supplied if the boiler was constructed under the supervision of a notarised body).

Another option is to certificate the boiler under the commercial inspection regime using an independent boiler inspector (I would recommend someone from the Association of Independant Boiler Inspectors). Under this regime the boiler is given a 2wp initial test and then a 1.5wp when assembled with all fittings and a steam test then thorough examination and hydraulic test every 10 years with an annual cold examination and steam test. Likely to cost you £300 - £400 a year. They will still require constructional evidence

If the supplier is unwilling to engage in dialogue with you that suggests a lack of confidence in his product!

Paul.

Duncan,

Just done a little 'light' reading from your link and it states;

CE marking

16.—(1) The CE marking shall be accompanied by the identification number of the notified body involved at the production control phase.

However the 97 document was replaced by (PED) 2014/68/EU, can't stay awake long enough tonight to trawl through that again tonight!

Paul.

Duncan, I believe you are correct that the manufacturer can issue the certification themselves but I understood they have to be accredited and audited or at least be capable of being audited (holding appropriate records / evidence) on a periodic basis. Without any audit process the system is worthless (although in my opinion CE marking is not worth a lot anyway!). Certainly one of the more reputable steel miniature boiler makers uses BES (formally RSA) because that is who issued the shell test certificate for my latest boiler. I am not sure what the smaller / copper boiler makers actually do as I have never bought one. Fizzy could perhaps enlighten us on that. I am aware of one individual who has constructed and CE marked a fairly large miniature steel boiler over the last couple of years and certainly he also used BES to verify the design calculations and issue the certificate of conformity.

The devil is in the detail lol, I am more interested in what the shortfall is to prevent compliance with the test code, anything that is compliant with the PED / CE system ought to be certifiable under the code?

Paul.

Ben,

lt might be more helpful if you asked the specific question rather then generalising. As stated above any pressure vessel / system commercially manufactured in the EU or for importation and use within the EU has to comply with the Pressure Equipment Directive and be CE marked. That is the law. CE marking will be overseen by a notarised body such as a classification society (Lloyds, DNV, BV etc) or an insurance company.

The test code for miniature boilers is exactly what it says, a code of practice not legislation. It is principally designed to bring hobby produced boilers into alignment with the PED and provides assurance to the insurer that the boiler has been constructed and tested to the agreed requirements of the code. It can be used to provide ongoing certification for use of a commercial CE approved boiler. It cannot be used to certify a commercially produced boiler for sale or underpin CE marking.

So what would you reasonably expect when buying a commercially produced boiler? Firstly it must be CE marked, secondly it will have an initial shell test 2xwp pressure certificate issued by an authorised body (could in some circumstances be the manufacturer) and thirdly it should come with a document package detailing materials, construction and maximum working pressure. It won't come with a written scheme of examination, a periodic 1.5wp certificate or steam test certificate.

Not sure if that helps, if you are more specific, more help may be forthcoming.

Paul.

'Testing' them at anything other than operating pressure proves nothing other than there is a free passage of steam so I don't see any real value in the practice. Few full size safety valves have that facility. For myself I am far more interested in that the valve lifts at the set pressure in normal operation. When lighting up a boiler the first thing I want to know is its operating pressure indicated by the red line on the gauge, no line no lighty, do not pass this point. Then I want to verify the water level and that the gauge glass passages are clear, with both these conditions satisfied plus an external visual inspection I proceed to raise steam, to the indicated operating pressure and confirm the safties lift - if not then either the pressure gauge is out of whack or the valves defective - further investigation required and until resolved the boiler is not fit for service. Lifting the valve manually at less than its operating pressure is far less important than a full pressure test and as Jon says not easy to do safely especially on a large or full size boiler,

Paul.

Gary,

Never having heard of a Trangia burner (sheltered life maybe lol) I consulted Mr Google! Many of the comments re suggest they are slow to boil water in a pan. I get the impression they have a relatively low heat output so in terms of a burner design for steam raising? I have not seen one burning but imagine there are many small flames from the various holes? Have you thought about a burner along the lines of the old paraffin stoves with a 'ring' wick and a large circular flame? They were designed to chuck heat out.

Paul.

Derek,

I would second Jon's comments, looks like you have made a very nice job of the parts you have done, in a relatively short time too. Don't forget you don't have to mount the cylinder in a chuck or on a faceplate but you can mount it on the cross slide of your lathe to do the bore. If final dimension of the bore in the casting is a worry you can make it a nominal size and turn the OD of the liner to suit! Steam port drillings between the port and the cylinder can be fraught! I am just about to embark on that job on my 6" scale cylinder in the next week or so. I am planning to make a jig to assist in getting the angle right. As Jon says looking at the rest of the parts you have done you shouldn't have any trouble doing the cylinder, just take your time and think it through. Size of available machinery can be a problem but I managed to make the complete water pump for my 6" between a mini mill, Hobbymat and an ML7, where there is a will there is a way! You can put the £600 you save towards a bigger lathe for the next project!!

Paul.

Derek,

Therein lies another problem as to what is a fair price. Certainly it is reasonable to assume that the hourly rate for a commercial jobbing shop which as you say has to incorporate various overheads will be higher than some one doing an odd job working in their garden shed. What constitutes a fair cost for the former is reasonably easy to break down and justify in terms of capital costs, rent, power, statutory costs associated with employment and wages. The latter is more subjective as it involves how an individual values their time. I know a retired fellow who does very occasional jobs that interest him, he has some decent machines that are 'paid for' so his costs are really power any consumables and his time, the question really is his time (and skills) worth any less than the commercial shop?

I have never machined a 1 1/2" Allchin cylinder (but have machined bigger cylinders for myself) so have no real idea of how long it would take but thinking along the lines of the steps and set ups required I would guess at least eight to ten hours as a minimum? Drilling and tapping the holes would be time consuming in itself. That being the case for a commercial shop £300 may be cheap.

Who ever you get to do it the most important thing is clarity in what you want done. It's worth bearing in mind that most model drawings are not 'proper' production drawings as they have no indications of tolerance or surface finish. A commercial shop would need some enhancements to the drawings, a minimum probably as an example (if a liner is fitted) being tolerances on the bore in the casting for the liner and the liner O/D to achieve the desired fit. You will have no redress on anyone if you give them the typical model drawing that shows the bore as say 1 1/4" and the liner 1 1/4" without giving an indication of tolerance or fit. The key to success on both sides is a clear understanding of what is required and what will be delivered and when, without this there will be frustration on one or both sides!

For a number of reasons I don't do 'commercial' work but this year I was approached out of the blue by an upholstery company asking if I could make a one off aluminium block for a piece of furniture that was lost or broken from a sample. The block was quite involved with a number of drillings and counterbores but the type of thing you would get as a die cast component from B&Q for 50p. I estimated for me to source a piece of material (it was quite large - about 2" long by 1" sq) and made the counterbore cutters and then machined the block it would be at least a couple of hours work so I quoted £50 all in. Obviously this was something of a shock to the enquirer as they never came back! The expectation was I assume because I am retired and my machines are my own I would do it for peanuts - like the old saying if you pay peanuts you get monkeys! If I had taken them my workshop stool for recovering I very much doubt they would have done it for 'love'.

Paul.

Derek,

The last line of you last but one post "I thought it maybe worth asking in case I can get it done slightly cheaper" may be off putting to some and possibly not get you many offers of help with machining!

As recently discussed on another forum I frequent when 'subbing work out' there are three main considerations, cost, speed and quality. The former and the latter generally are inextricably linked in that if you want high quality the cost will generally be high although it is not guaranteed that if the cost is high you will definitely get good quality! The middle one, speed, is also indeterminate as good 'contractors' are generally busy so there will be a waiting time.

Paul.

Ron,

Profile on that one looks better than the first one (from the pictures). One way to check the tool geometry and get a rough and ready "full form" tool is to check out in a bolt of the same pitch (using it the same way as your screw cutting plate gauge). That will show you if the tip width / radius is somewhere near correct. I also only use the cross slide and don't bother setting over the top slide with the proviso that if the thread is tearing I add a couple of thou on the top slide to move the tool over a touch and bias the cut on one flank. Useful if the tip of the tool is too pointed as once you get to depth and the root is too narrow and then crest too wide you can kiss a bit from each flank, cleaning them up and getting a better finish and evening up the thread, if you get my drift? Good wheeze to get things right if the tip is too narrow and you are at full depth, using the top slide at half the thread angle doesn't give you that flexibility.

Paul.

Ron,

I am by no means any authority on this at all lol. I have limited experience of uploading various videos from various camera sources which have been successful more by trial and error and luck I would say rather than any kind of knowledge! I THINK it is more to do with the resolution that you use to shoot the video in the first place as to the ultimate file size. In low resolution a one minute video may have a file size of a mega byte or two but in high res many megabytes. One video I uploaded to youtube of my gear cutting was 10 minutes long, I had to if I remember right upgrade my account (still free) to allow it to be uploaded and it took several hours! I just set it to work before I went to bed and it was done in the morning. I guess it also depends on the speed of your internet, since we accepted a fibre upgrade from our provider for the same cost as ordinary broadband I can upload pictures to the other forum I use in seconds rather than minutes. The time taken can be a frustration but even on snail band it gets there in the end.

Merry Christmas by the way and look forward to seeing your progress in the new year.

Paul.

Doh, lol. Of course, must be too much Christmas spirit!! Don't know how I missed that when I always calculate my own divisions rather than refer to the chart that came with the dividing fixture!

Thanks,

Paul.

? You have lost me there, please explain how you get 13 from a 65t gear wither as direct division or via a 90:1 reduction.

Paul.

"Of course you must" - broad and sweeping generalisation! Only if you don't have a thread dial on the lathe or are cutting pitches not compatible with the dial (some metric pitches on an imperial lathe as an example). When you cut a thread it is common to make an undercut at the shoulder as a run out for the tool, depends how quick your reactions are and the speed of the job as to how wide that needs to be. If reverse cutting ideally you still need an undercut to position the tool in before starting the cut. On 'proper' lathes there are various creative solutions to assist with screw cutting, Holbrook have a stop system that will disengage the saddle / lead screw on a dog clutch for you at a predetermined point, you can then retract the tool and return to the start and use the dial to re-engage. Colchester had a quick retracting cross slide, small lever under the normal hand wheel which when tugged snatches the slide back to clear the thread. Again you can then disengage the half nuts return to the start put the slide back, wind on the next cut and re-engage. Both methods make thread cutting quite quick as you don't have to reverse the lathe. On some of the big traditional lathes I have worked on like Denham or DSG if you had to reverse the motor after each cut you would be there all day with the inertia in the system!

Paul.