ME Vertical Boiler & Hand Pump

Yes looks like the drawing is wrong.

Revised Fig2 showing the correct tool angle will be in the next installment.

J

With reference to the description of the machining of the M4 fixing holes in part 4 Machining part 1 paragraphs 2 & 3 Martin says to position the datum to the right and then drill the holes at -11mm and -29mm. However on the drawing fig 3 the datum is shown to the left at the 11mm and 29mm dimensions are from the opposite end. Since the holes are not symmetrically placed might this cause a problem?

Another query - when people say drill and tap M4 x 8mm deep, is the 8mm the length of the thread or the total depth of the hole? Depending on your plug tap you might need quite a bit more clearance at the bottom of the hole to obtain 8mm full thread.

Thanks for any replies.

Andrew

Yes, sounds like he has got his left and right mixed up. Would also be better if the drawing had the dimensions taken from the datum face too.

Generally drill 8mm deep and then tap, go don't reall gain anything by having more than 1.5D of fixing in a tapped hole so the 8mm drill depth should allow a thread of about 6mm or 7mm if you grind the point off the plug tap.

Regarding the missing Fig 1 This does not seem to show the cylinder as it is in Fig 3 as the section has it parallel on the outside but Fig 3 (part 4) has the end reduced to 10mm to fit the 10mm hole. and I'm not sure why the 10mm dia part is as long as it is shown on the drawing. Also seem to have ? in place of the diameter symbol in a couple of places

Edited By JasonB on 11/04/2018 12:24:03

I'm a fairly new member and I've only had my WM180 lathe for the twelve months now so somewhat inexperienced although I did go through the engineering training school nearly 50 years ago. I am following this series with interest and noted that someone commented on the assumption that a mill was needed. As I don't have a mill yet I did the pump body machining on my WM180 with a jacobs chuck (!) and vertical slide fitted as in the picture. Taking fairly small 1mm cuts didn't really have any problems. Coming to the brazing, not having a large brazing torch, i used my plumbing torch on the body and achieved a satisfactory result as far as I can see (first time I've brazed anything). Thought this might be of interest and I'm looking forward to the rest of the series. I imagine I might need a bigger torch for the boiler itself.

Good news for all who are interested in making the M.E. boiler.

M.G. has now completed the articles on the hand pump and will commence the boiler build next month.

Also it will feature every two weeks instead of every month.

I hope M.G. includes a full detailed drawing of the boiler at an early stage so builders can see the whole picture before he starts his constructional series.

Geoff

I also hope the editor removes the "hand pump" from the page heading now the boiler description proper has begun

looking at the boiler in issue4591 it looks like the boiler shell bushes are threaded into the boiler - is this a good way to get the silver solder to run in or are they flangeless bushes so need to be threaded to keep them in place whist silver soldering?

I think the reason is as you say to stop them falling out while soldering this would apply to both flanged and plain.

Martin does mention that the design has been tweaked a few times following feedback from builders and I suspect one or two may have had a bush come out so he has added the screwed method.

You would want the filed nicks as suggested to help the solder flow through the joint.

I'm just making the SS flaring rings and flaring drift in this series and they have been specified with some small external radii R0.5 and R1. Would anyone have any suggestions as to the best / easiest way to achieve these radii on the manual lathe?

For something small like that you can hold a file against the rotating work and roll it around the radius which will soon just soften the corner. Do make sure you have a handle on the file. If you want a small chamfer can be turned first and then finish with a file.

I've flared the tubes as described in the article. However the copper I had must have been harder than the author's as, far from being a gentle tap, it took quite number of firm blows to achieve the desired flare. On average the flare was 0.6mm on diameter for the larger tubes and 0.3mm on diameter for the smaller tubes so I suspect this will be enough to stop them falling through. There was no sign of splitting but maybe if the tubes are hard drawn then they would need annealing before working on them? I bought all the materials from Noggin End as advised but it doesn't mention the hardness on the web site.

Was there a previous series on a vertical boiler published in ME some time ago? I seem to remember seeing it in one of my bound volumes. I have started to plough through them but there is so much material I have given up.

Mick

Mick,

There have been plenty of vertical boiler construction articles over the years, right from Volume 1 of ME!

Searchable index here.

Most recent detailed construction series in 1997 by Stan Bray (GLR vertical boiler), Vols 178/9, starts issue 4037, page 303.

Regards,

Phil

Thanks Phil. Thanks also for the Searchable Index- very good.

Mick

I have come to the boiler assembly on page 511 Model Engineer 28 September and there are two measurements for the distance over the outside of the tube plates. The text says 102mm and the photo 75 says 100mm. Not much in it but may as well check which is correct?

In the latest edition, 21 Dec 2018, boiler fittings it specifies 10mm AF brass, would it not be better to use Phosphor Bronze? This would avoid the possibility of dezincification.

Yes I agree any bush soldered directly into the boiler should be bronze for the reasons you have given

The bushes are bronze, the fittings brass

Myself any that will be in contact with the water I would do in bronze, those only likely to be in contact with steam I would use brass for. It is the impurities in the water at temperature that can cause dezincification not the steam.

I'm part way through silver soldering the boiler and notice that after soldering the two tube plates and fire tube assembly (and first two bushes) with medium temperature silver solder the assembly is then soldered to the barrel using the lower temperature solder but then returning to solder the last two bushes with the medium temperature solder. Doesn't this jeopardise the previous lower temperature solder joints? Or have a I misread the article?