Hello and a part-built blowfly

[Lisa]

Finished off the other rear cylinder cover today, these still need the hole for fixing the slidebar drilled and tapped, but otherwise they're done.


Meanwhile thoughts turn to drilling the bolting holes for the front cylinder covers:

It might actually be simpler to clamp them to one of the rear covers, and just use that as a jig, we'll see.

[Lisa]

I woke up with the intention of spending the day in the workshop today, but ended up catching up on laundry, eating chips, and going for a walk with dad (well, I walked, dad sat in his wheelchair), which ended up being a rather pleasant day.

I did drill one of the front cylinder covers though, so that's one more part completed.

[Lisa]

... and then I did the other one once dad's asleep.

Incidently, the bit of metal clamping the cover to the rotary table is an out-of-tolerance keeper plate from the 'Heidi II' I built 15 years ago.

So that's both of the front cylinder covers finished now.


Then I spent a bit of time getting the vice mounted square, and will do the cylinder drains next, as those lugs are in the way for clamping and doing the ports.

[Jim]

You're doing a cracking job there Lisa in between all the other things you're  doing. I love the engineer's precision hammer you have there too. A very handy bit of kit I must say.

Jim

[Lisa]

Thanks Jim.
The 'precision hammer' is a rubber mallet, handy for not marking the job when giving it a smack to ensure it's seated in the vice... and for tapping the vice to get it square.

[Jim]

Excellent Lisa. Your engineers hammer is ver similar to mine and the great thing is it doesn't damage the wall when i throw it following another muck of mine.

Jim

[Lisa]

Got a little bit done today, drilling the cylinder drains; these need to be tapped ¼x40 for the drain cocks, but I don't have a bottom tap so that can wait. Also there's not enough headroom on the mill to get a tap and tap follower in, so they'll have to be done freehand; unless I can do them in the bench drill, we'll see.


You can also see that the casting doesn't quite line up with the actual positions, but it'll be hidden by cladding anyway.

[Jim]

I must admit I do all my tapping free hand Lisa. I did make up a guide from a piece of round bar but it turned out to be very fiddly and I could tap the hole just as easily free hand. I also like the 'feel' you have when tapping.

[Lisa]

I generally do as well Jim, though I like to use a guide on some jobs; such as blind holes into expensive cylinder castings. I've been intending to make a tapping stand for about 20 years now, but still haven't, and am still doing fine without it.

[Lisa]

Waking early has given me a couple of mornings in the workshop before dad wakes, which works out rather well. So work continues on the cylinders.

I drilled the cylinder drains on the other cylinder, and oddly the casting aligned better on this one than on the other.


Next I figured I'd finish up the steam chest covers to size, which is getting me a nice collection of bits that'll bolted together eventually.


Then I thought I'd drill the hole for the main steam pipe inlet, and discovered another oddity in the plans:

No idea what distance the hole's meant to be from the 'front' (actually the back, another error), so have put a query out to some other Blowfly builders to see what they've done.
I thought maybe I could be smart and just get the measurement from the centre of the cover by checking the distance between holes in the bottom of the smokebox... but that would result in a D shaped cutout on the front edge, so I'll just wait and see what others have done.

[stevep]

The dimension is missing, but can't you scale it from the drawing?

[Lisa]

The drawing's not as too scale as it looks, but guesstimations put it at ¾"; still going to see what others have done first.

[racinjason]

Lisa if you look at the smoke box drawing it shows the blast pipe and steam delivery holes this makes the dimension you need to be 1 & 5/16 inches to the rear as you have already seen.
regards Jason.

[Lisa]

Jason, I looked at that, but that dimension would put the centre of the hole 1/32 from the edge of the cover (as the blast pipe is centred on the cylinder), which clearly isn't workable.

Responses from others say ⅝", so that's what I'll go for.

[Lisa]

A bit of scribbling and maths to work out the handwheel turns and positions for each of the steam chest bolting holes. A DRO would simplify this of course:


Which worked out rather well:


So that's another part complete:


Once the other steam chest is drilled I'll move on to ports and passages.

[Lisa]

Well that looks more complete than it really is, steam chests and all the covers are now finished, will make a start on the ports tomorrow if all goes well.
Then there's 56 small blind holes to drill and tap.

[steamer5]

Hi Lisa,
Looking good! The careful number crunching has paid off great! Keep at it, 56 tapped holes shouldn’t take too long...........


Cheers Kerrin

[Lisa]

Thanks Kerrin, I'm mostly wondering how many M3 taps it'll take.

[simplyloco]

Aug 29, 2018 5:04:19 GMT Lisa said:

Thanks Kerrin, I'm mostly wondering how many M3 taps it'll take.

I suddenly have lots of them, but the postage to Oz is a bit steep...

[Lisa]

I've found some trying to sell them for $50 each locally. Probably cheaper to ship 'em from the UK if that were the only option.