Here is a list of all the postings mick H has made in our forums. Click on a thread name to jump to the thread.
|Thread: feedwater preheater|
I am considering fitting a feedwater preheater to a small marine type engine. The heater would be of the "concentric pipe" type whereby the feedwater will pass through a 3/32" copper tube which is jacketed by a larger bore tube.
What bore should I make the jacketing tube ?
What would be minimum length of jacket to be effective ?
How long & piece of string come to mind but if it is of any assistance the pump bore is 5/32" with 3/16" stroke.
|Thread: Boiler testers and material verification|
The material surplier should give you a test certificate (not just a sales receipt) which specifies the chemical composition, tensile strength, etc for that batch of material..
I have never ever received or been offered such a document.
|Thread: Locking Levers|
In my opinion that is an outrageous price. Arc Euro, (indexable lockable handles) for instance are half that price.
|Thread: Rotary Valve engine having more than two cylinders|
Yes, Oliver it is the same engine but I did make a few alterations / additions. Firstly I ran the crankshaft and crankshaft valve linkage in miniature bearings (arguments for and against). Secondly, I fitted Viton piston rings. There is a feed pump mounted on the RH side of the engine driven by an eccentric on the valve and a Roscoe lubricator fitted opposite the steam intake. I may also have tinkered with piston diameters but I can't remember the details.
Duncan is quite correct regarding the valve being a good fit. I lapped it in and have surprisingly minimal leakage, mainly at the feed pump end. I am working on an O ring based solution to this.
As regards the self starting problem, I have fitted a needle roller clutch (one way) bearing to the output end of the crankshaft which just requires a nudge from a servo to push the piston past TDC and away she goes.
The engine is shamefully filthy at the moment but if you would like a picture I will clean it up.
Hallo Oliver and welcome. I have made the two cylinder version and a nice little motor it is, running smoothly and economically from a 2.75 diameter vertical boiler. It suffers from not being a "self starter" if the crank ends up in the "wrong" place when stopped. I have found a way around that though. If you can figure out the valve events for a 3 cylinder version it would be of great interest.
|Thread: Upgrading to fibre optic broadband|
I have just run a test and it returns 2,33 Megabits/sec. Infuriatingly slow and at most times only just workable. To add insult to injury, I received an email from BT yesterday offering a free fibre upgrade. After I had jumped through all their hoops in the application process they said it was not available to me .....ha!ha!ha!.....what a great laugh. And for this I pay £40 per month. I am awaiting a call from a "manager" to deal with my complaint .......who will tell me, as I have been told over the last 20 years that I will get it in a "couple of months". The lies and deceit endemic in that company is beyond the pale.
|Thread: Up and over door seal|
Thanks gents. Very useful.
As far as weatherproofing is concerned my "main" (tiny) workshop is OK but I do have to keep a certain amount of stuff in the garage which has an up and over door. During periods of heavy rain the up and over garage door lets in water as there is no seal at the bottom. I would like to fit a threshold seal whilst the weather is reasonable. Any recommendations will be appreciated.
|Thread: Supaburner's for Model & Toy Steam Boilers Explained|
Fascinating stuff Blue Heeler. How do you control heat output?
|Thread: return crank movement|
I think that I might have used an appropriate Loctite grade (say 638) to fix the insert which I am pretty sure would obviate silver soldering. If the wheel is cast iron you may well have a lot of trouble silver soldering it.
Hallo David. Can I ask again about the size of the loco. What gauge is it?.....ie what is the distance between the wheel treads. I did offer some advice on fixing a return crank for a 6-coupled loco a short while back. That was a Gauge 1 (45 mm track) loco though, which is a completely different kettle of fish as regards the size of crankpins etc than say a 5inch gauge as there is only a tiny amount of mating surfaces. So the fix will be different.
As regards the repositioning of the crankpin I can only offer my commiserations. It seems to me that there are few options other than going back to square one and ensuring all the crankpins are properly aligned and the wheels accurately quartered. But, if the loco is of small gauge you might get away with.....and it makes me wince to say it...........leaving the centre coupling rod bearing snug on the crankpin and take a tiny amount of material from one or both of the coupling rod end bearing surfaces. Even if this goes horribly wrong you can rebush the coupling rod bearings to get back to where you started.
The above quick fix has worked for me in the past with no observable problems in running.There are far better qualified and more knowledgeable than I on this forum who might assist you further.
What scale is the loco David ?
|Thread: Tapping a thread|
What is the component that you wish to tap?
|Thread: C section plastic extrusion|
That's the sort of stuff John....now to find it in brown plastic to save on painting it. My local builder's merchant no good.
Any ideas on where to locate 20mm C section plastic extrusion to protect tops of workshop end timbers ?
|Thread: Do you clean your workshop at the end of the day?|
Worrying over this very subject, I asked a retired engineer friend how often he cleaned up his lathe and workshop etc. He replied "When it needs it." Try as I might I could not get him to expand on this answer.
|Thread: Boiler cross tube leak.|
Thanks for that bunch of very interesting posts gents. I shall re-read them all several times and tuck the advice away for future reference. As for my boiler, I seem to have cracked the problem with a bit of comsol and she is holding pressure well. We shall see what occurs when I get it into steam.
Touching again on "chemical sealants" as a solution. Radweld is an obvious lo-tech example. I note though that the same maker markets a product called Wonderweld which purports to seal cracks in motor car cylinder heads and engine blocks. Pretty extreme conditions and pressures there I would have thought.
I have just completed a vertical boiler build which has a central flue with cross tubes. Aware of the propensity of this design for leaks, the flue and cross tube assembly was silver soldered with SF24 and the whole assembly subjected to a 120psi hydraulic test for several hours. I then silver soldered the flue assembly into the boiler barrel using SF55. On hydraulically testing the whole boiler I noticed a very small drop in pressure of about 5psi over about 20 minutes and on investigation found the tiniest of weeps from one of the cross tube joints. The received wisdom seems to be, scrap it and start again. I will not do that .....yet.
My first thoughts centred around Comsol. Do I need a special flux?
Second thoughts were around a sealant but have things moved on from horse dung and oatmeal? Would it be very wrong to try say Fernox leak sealer provided the boiler was thoroughly washed out after a seal is effected.
This is the first of 8 boilers that has failed on me and although I accept it was my fault, whilst soldering up the flue assembly, the heavens opened and I made the error of trying to get the job done ASAP instead of concentrating more on the quality of the braze. As they say around these parts, you only get wet once.
|Thread: Vertical boiler flue pressure test|
Brilliant. Thanks Jason.
I am building a 3" vertical boiler with a centre flue with cross tubes. When talking with a wise old gent at a show last year he advised me that if I were to build such a boiler that I should do a hydraulic test on the flue and cross tubes before the assembly is silver soldered into the main barrel. The flue is 1"diameter. I am quite familiar with the mechanics of hydraulic testing but how do I go about sealing off the flue tube please. The tube is already cut to the required length.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.