Here is a list of all the postings Bill Dawes has made in our forums. Click on a thread name to jump to the thread.
|Thread: Steam Raising Blower|
Hi Duncan I would have thought the axial load load on such small impellers will be negligible as both mass and suction thrust will be very small. A ball bearing will take a good thrust load, we accommodate very high thrust loads on deep grove ball bearings, around 600 lbsf or more ( in old money). Bearings slightly bigger than the steam raising blower ones of course.
On the subject of blade shape again, curved blades both forward or backward are potential problems where dirty gas is involved. Radial blade the best, straight backward sloping not as good but a more efficient compromise.
As a fan engineer I feel I should be making my own blower, not at he stage where I need one just yet but my Emma Victoria is inching (painfully) towards completion so I guess I will have to start thinking about it. Any thoughts on best place for a 12v motor guys.
You see very simple impellers on all sorts of things such as car alternator that Paul mentioned, oven circulating fans, cooling fans on motors etc. A circular plate cut through at intervals and a blade folded out is a classic. just needs a a piece of round bar fixed in the centre and bobs your uncle. Not very sophisicated and hardly in the 'fan engineering' category but it will produce an air flow.
Hi Peter, fan engineering is both a science and a black art. I have always had a saying with fans, if you change something and think it will work it probably won't, or if you think it won't make any difference it will.
Blade type is selected for various reasons, efficiency or application mainly. The ideal is of course the most efficient, especially in these days of ErP regulations (Energy related Products) however sometimes an efficient blade would be not be fit for purpose for some heavy industrial applications. Cost is also a consideration, straight radial blades are less costly than fancy curved blades so as with many things it's all a balance (excuse the pun)
I wouldn't worry about blade type too much, a simple radial blade will give good performance for a steam raising blower, number of blades will be restricted by the space available on a tiny impeller like this, I would probably aim for about 6 blades.
I am talking here about centrifugal fans of course not axials.
The fan casing (volute) converts the energy off the blades into usable energy at the outlet and of course is directional, impellers can also run in a circular housing, probably with guide fans as found on large furnace fans, discharging 360 degrees around its periphery, some losses in performance compared to a volute. The part of the volute where it is closest to the impeller, callled the cutoff, influences the pressure development, too much clearance looses pressure, very close however creates more noise. Again all a bit academic really for this application.
As an industrial fan engineer of some 60 years some guidance I can offer on blades is that a flat radial is the best blade for handling dirty gases. Backward curved are more efficient than radial or forward curved but do not like dirty gas too much, you get build up on the underside of the blade which will cause out of balance. Of course I say this on the basis of fans in industrial processes fthat are far more arduous than a model loco exhaust so the penalty of using the 'wrong' blade will probably be not too significant for the limited time they are used.
The blades can be pop rivetted, stresses will be very low in an impeller of this size. My company make high pressure blowers up to 1.2m diameter with rivetted impellers.
|Thread: Macc Models Excellent service|
Yes been using Joe for some years now, bit shaky at times in the early days but now excellent value and service, might be a coincidence but a step change seemed to take place when he got married!! You can also be sure your goods will be well packed,!!
Carry on with the good work Joe.
|Thread: Gloves in a Bottle|
Reminded me of my apprentice days on the shop floor back in the 60s, we used pink stuff called Rozalex, it didn't soak in, just had this goo on your hands which were black within a few minutes starting work (we used a lot of cast iron in those days) Amazed to see it is still available, hadn't heard of it for years.
|Thread: Jobs we had as kids|
Ah yes, lovely ladies, the typing pool in the mini dress era.
If someone had told me then that in the future I would be doing my own typing rather than having a short hand typist i would have said they were mad. What was someone saying about change for better or worse?
Still I did marry one of those typists at Alldays, still going strong.
A good chance the forge hearth and bellows were Alldays & Onions.
Still see some in rural museums etc. There is an A&O pneumatic hammer at the Iron bridge museums.
Born and grew up in Brum. Left school at 15 in 1956, teachers nagged the life out of me to take 11 plus but for some strange reason did not want to go to grammar school. Did paper round before I left school and then hopped on a number 44 bus to run errands for my nan, (opposite Tyseley engine sheds) strange foods like chitterlings, faggots and peas (red hot much burning of hand) pigs trotters etc.
Bus conducter sang and whistled his way along the route shouting out all the stops.
Can still smell the workers from Rover, Girling brakes, Dawes cycles, King Dick tools all in that Tyseley area (suds oil) and Smiths crisps cooking fat at the bus stop queue.
Intended to go into the motor industry so wrote off for an apprenticeship to 'The Rover', where my dad and grandad and lots of uncles worked. Unfortunately (at the time) as I had left school at Christmas they had filled their allocation. Went to Alldays and Onions, ( must have some premonition of the demise of the motor industry) fan and foundry equipment manufacturers as an apprentice. Good old fashioned apprenticeship, went to tech and got HNC. Sometimes wonder if I should have gone to grammar school and Uni but at the same time cherish my days on the shop floor before going into the drawing office then tech sales and finally as engineering director. (not with Alldays but still in the fan industry) The fact was that in my working class environment I did not know of anyone that went to uni.
Many great memories of my teens, (you don't worry about all the stuff that gets up my nose now)
Rock and roll, Brum was amazing for that, so many groups (bands were those people that played old dance music then) every pub, dance hall, school halls, community centres, working mens clubs (tone it down a bit lads) had rock groups on. And of course the smogs, you could chew it, thankfully long since gone. Oh and I remember Brum was, I believe, the first city to introduce dim/dip lighting on vehicles.
That was then, now living in rural Somerset, Brum not to my taste now.
|Thread: Brook Compton 1 phase motor KP6345|
Yes, that's what I mean about Brook info. I have one of those little books tucked away somewhere, I wasn't on service side, tech. sales in the fan industry, I think one of the reps gave it to me. Absolute mine of information.
Compare that with a Siemens catalogue, an absolute nightmare of codes, part numbers, reference numbers, optional build numbers etc etc. eveything but useful information. To be fair ABB do some good tech stuff.
By the way, my understanding of wavy washers on electric motors, as well as other bearing arrangements, is to pre-load the non drive end bearing which is the free bearing. The drive end bearing being located. Pre-loading helps to stop the free end bearing from 'rattling about' a relative term of course as clearances between balls and races is extremely small. This helps with reducing noise and wear. I cannot be certain but I think wavy washers are only used on small motors, the load on the free end will be quite small and a too lightly loaded bearing is not good, the rolling element is likely to skid not roll.
Very late in the day I know but came across this post looking on line for something.
I am not a Brook man or any motor man come to that except have many years experience of using motors on industrial fans which is my game.
Brook motors was an excellent company, you could always have a chat directly with an electrical or mechanical design chappy at Huddersfield if you had a problem, many of the local sales engineers were also time served Brook men through and through. The old Brook technical literature was excellent, I still retained them as it contained information not found in present day ones. (I still work one day a week as technical consultant) I remember well the traumatic time they went through as they were taken over by one company after another with factory closures, redundancies etc, this caused customers huge problems with deliveries but you couldn't help feeling sorry for the people at the sharp end facing the wrath of customers, the stress caused early retirement for many excellent people. A far too familiar story of british industry unfortunately.
The sad reason for Brooks inability to help is that old data and records like that is probably long gone. The people that may have memory of how things went together are also long retired or not with us.
Many years ago I decided to try varifocals as my ordinary specs (for distance) drove me mad at places like supermarkets, take em off to look at labels, back on again to look down the aisle.
The optician (my local private one who are excellent} told me it would have to perservere to get used to them. Well try as I might I could not get used to them so went back to my previous ones. Move on a few years and had a chat to my optician who said lense technology had improved since my last ones so I had another go. Absolutely fine no visible line on the lense or wierd sensations. Wouldn't be without them.
|Thread: Miracles do happen|
I posted some time ago about that little gremlin that lurks under work benches in our workshop ready to snatch away anything we drop. Well today a new watch I ordered arrived, just a cheap everyday one. Needed to adjust the clasp so went into garage for a sharp pointy thing to depress the spring loaded pins, PING, away it shot to the back of my workshop, got a torch hoping against hope and miracle of miracles there it was neatly nestling on the rubber mat.
I shall be talking about this for years to anyone I can bore with my workshop tales.
My wife and myself have been with Tesco mobile for some years now and we can honestly say never had a problem.
My gripe with BT (well one of them) is the difficulty of finding simple straightforward information on what you've got, what options there are etc. and how they managed to design the bill to be such a mess is a masterpiece.
Sky are not much better in that respect, always difficult to find ways of reducing your bill if you need to, the important things the consumer want are buried away somewhere.
We have just had Truespeed broadband run down our lane, can't justify the cost but looking at their website it appears to be simplicity itself, just a few simple tariifs depending on what usage you want and similar for phone usage, otherwise no installation cost, no extra for line rental etc. I'm tempted.
By contrast had a message from Tesco mobile saying they will 'never change prices mid contract, never have, never will'.
I find BT the most infuriating company to deal with. Their website is dreadful, tarrifs confusing and 'contracts' only of value to BT. Just had letter from them blithely stating they are going to 'upgrade me' extra hours of calls that I don't need and extra cost of £4.50 a month thank you very much. This is on a 'contract' set up in March.
Changing provider is not that straightforward where we live, many other providers can't do our area.
|Thread: Statfold railway|
Hi all, did anyone make it to Statfold?
|Thread: Cleaning up new Sieg SC4 and how to remove apron|
I have a Sieg SX3 milling machine from ARC and a WM290V lathe from Warco, both Chinese made of course. I do recall that a supplier had stopped offering the strip down service but can't remember which one but thought they said it was no longer neccessary as they had worked hard with supplier to improve quality and inspection. Suffice to say, after a clean up I used both virtually straight out of the box as it were and have been very pleased with both after about 3 years use.
|Thread: Static balance gadget|
The way se used to statically balance fan impellers was to mount them on a mandrel, place on a pair of knifedge rails and note where the impeller comes to rest, correct by trial and error with lumps of putty/bluetack, when in balance weigh your putty and permanently fix metal weights (or remove metal at 180 degrees if there is enough)
Now use fancy electronic machines of course but static balance is good enough for narrow components unless you have a tight spec to work to.
Of course the knife edges have to be level to ensure accuracy.
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