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Member postings for Cornish Jack

Here is a list of all the postings Cornish Jack has made in our forums. Click on a thread name to jump to the thread.

Thread: Steel castings?
16/11/2011 17:11:52
Thank you Jason.
No, not at all sure what it is. The external and internal surfaces were 'as rough as guts' and the first cuts were like getting under the skin of iron castings. However the brackets support the crankshaft which is made up from quite thin section brass strip webs and insubstantial pins in brass bearings - overkill and underkill??
Rgds
Bill
16/11/2011 14:39:30
G'day all.
No doubt rthis will seem somewhat odd, but how common are STEEL castings?
I'm in the middle of making a mess of a Sieg Hot Air Engine kit and machining the 'A' bracket supports. They looked like (the expected) alumimium castings when first seen but machining generated blue chips and some sparks!! Can't think of any particular advantage of steel in this area and it certainly makes life somewhat more challenging. Any thoughts as to why Sieg went down this route, anyone?
Rgds
Bill
Thread: HAE03-1 Hot Air Engine
11/11/2011 11:31:44
Ian, thank you again - useful information. The Utube clip sounds interesting but I've only found one reference to this kit so far (the kit producers) on a Google search. Will try another search. Will also dig out some power hacksaw blades for future reference.
Rgds
Bill
10/11/2011 14:16:17
Ah Ha! Bingo - thank you very much, Ian.
Nicely timed advice. The final parting tool has survived to produce 20mm deep fins and the executive decision has been made - no deeper!
With a hot air engine experience level of zilch, I am very much fumbling my way through this one. The kit is of materials and two ready made cylinders and pistons - no written instructions at all. A book of drawings of individual parts and an exploded view is what I have to work to. One of the more 'challenging' bits still to do is a transfer passage across the central plate - appears to be about an eighth diameter and angled through the quarter inch plate at about 170 degrees (if that makes sense?) Haven't yet worked out how to do that
Rgds
Bill
10/11/2011 11:03:30
Thank you Ady and Gordon.
Re. the shaper, I can see the advantages but I haven't yet got my shaper operational There's also quite a difference between 12mm and 25mm!! Maybe if (when) the present setup turns to worms I'll rig the shaper.
The shrink fit fins sound ideal from the accuracy point of view - but "there's the rub" - my accuracy tolerances range from 'close enough for Government work' via 'a smidgen' to 'Good Lord, that was lucky!!!'
Might have to make an executive decision that 18mm is deep enough
Rgds
Bill
09/11/2011 22:05:40
Thank you Jason.
Yes, the tool section is probably a lot of the problem. The ground-to-size versions were from quarter and three eighths square stock and even at that size, it was taking over an hour to get them to size before honing - being done on a bench grinder, off hand. The cuts were taken with the tip just below centre height and as square to the work as I could make it. Considerable variation in swarf produced from one tool to another - some produced a nice gleaming almost continuous 'slice', while others, the latest one included, produce a sort of fine powder with occasional 'blobs' of fine curls. The noise is enough to wake the neighbours!! Onwards and inwards!!
Rgds
Bill
09/11/2011 18:45:36
Thank you Ramon - our posts crossed.
Yes, WD40 does seem to get in the 'tubes' a bit!! Will try paraffin for a change.
Looking for ward to next year's Forncett
Rgds
Bill
09/11/2011 18:40:47
Thank you J and Clive.
Re. type of tool, 4 x ground square bits and 3 reground thin parting tools. The most recent is another square HSS ground to width. I have a few clamped blade parting tools but they are 1.5mm width and seemed to flex and jam up rather readily. WD 40 helps a little but I try to feed with the left hand and use the longitudinal feed to widen the slot so a bit short of hands!!
Any thoughts re. the finning depth as regards effect on running/performance, anyone?
Rgds
Bill
09/11/2011 14:51:12
G'day all.
Just having a break from grinding and honing the EIGHTH (!!) parting off tool for the main cylinder of the above kit ... the previous seven have snapped(6) and bent. To paraphrase Lady Bracknell - "To break one tool is unfortunate to break seven seems like carelessness!!" Mebbe so but I'm doing my best. The problem is the requirement to produce eight fins 25mm deep 3mm wide at 5mm centres in aluminium. To avoid over widening the gaps, I've ground the tools to slightly less than 3mm and for a length of 27-ish mm. The ali stock is approx 75mm diameter and I'm using bottom normal speed on a Trileva ML7 (200ish rpm). I've so far managed to get 7 slots to approx. 18mm deep and one to about 12. The material is ex RAF Workshop scrap bin but seems reasonable except for the occasional 'inclusion' (?)
At last to the questions - a)Any suggestions as to improvements to the above techniques and
b) Anyone with hot air engine experience care to opine as to whether the 25mm depth is ESSENTIAL or just a nice round figure plucked from the air? - If the latter, would the present 18mm serve the (presumably cooling) purpose?
TIA
Rgds
Bill
Thread: A good 'Model Engineers Day Out'
03/10/2011 11:42:51
Bill, Ramon et al ... let me add my thanks and congratulations also! Super day, exceptional models, both in variety and quality. The full size engines were awe-inspiring - I did a 'by eye' calculation of the size of just one of the crank webs on the big beam - about 2'6" x 2'.0" x 9"!!! ...that is serious metal!! Steam and hot oil ... Aaaah! lovely! Couldn't manage the whole day - knackered back and knee past its 'sell-by' date saw to that - but hugely enjoyable. Last, but not least, special thanks to Ramon for his patient explanations, particularly of the anodising process - model engineering expanded to encompass chemical experiments and the results truly superb.
Rgds
Bill
Thread: electronics
26/09/2011 16:41:57
John - thank you so much! Looks like the very thing and some interesting potential other bits as well. Much appreciated.
Rgds
Bill
26/09/2011 11:38:36

I'm similarly interested in an area which has always left me a bit 'mind-boggled' - pretty easy to bring about!! Most electronics treatises leave me wondering whether we're using a common language, although I've managed to do the basic practical things like wiring up workshops etc.
I would like to 'fiddle' with simple circuitry and integrated circuits etc., to which end I've got a couple of beginner's breadboard kits plus a more interesting device shown in the photo. Purchased secondhand, it came with no instructions and 'Net' searches have produced nothing. Does anyone, a) recognise it or b) have any thoughts as to where I might find any useful info, about it, please?
Rgds
Bill
Thread: A good 'Model Engineers Day Out'
23/09/2011 16:46:59
Thank you, Bill
That sounds much better! Looks like a good day out, indeed - looking forward to it.
Rgds
Bill
22/09/2011 18:15:58
Hi Ramon (or Bill)
Sounds good (about an hour away) but just had a look on Google Earth and the postcode given looks a bit sparse for parking Is it just Google's geography wrong or are arrangements made to suit?
Rgds
Bill
Thread: Myford C7 Capstan
12/09/2011 15:23:07
Rummage successful!! However only limited info. Just half a page on the Tri-Leva setup plus another half page and photos of adjustment and a cutaway drawing and parts list for the Tri-Leva Speed Selector itself. Nothing on the capstan tailstock, although mine is pretty straightforward in operation.
Ady's ref. above is the same thing, so worth a d/l
Rgds
Bill
12/09/2011 15:02:56
I have a similar setup, with gearbox and clutch and most of the available accessories. Will have a rummage in the shed for the manuals.
Rgds
Bill
Thread: Health
30/08/2011 12:11:50
Indeed, Ady ... $*&%$*$$** Google again!! Rapidly becoming more invasive (and pervasive) than the odious Microsoft! Looking at their Adchoice tag indicates the lying nature of their cookie code - nothing in their listing there that would include either of the ads referred to. It becomes increasingly difficult to find HONEST software program(me)s.
Rant over
Rgds
Bill
Thread: Proof reading, what proof reading ?
29/08/2011 14:15:23
Engine???
Rgds
Bill
Thread: RC engines of the future
25/08/2011 12:13:32
Used to be a (Dutch??) pulse jet demo team did the Model aircraft Fly-ins back in the 70s. 'The Shadows' rings a bell. Last time I saw them was at a w/e show in the North West. I was in the sales hangar - about 400 yards away when they started their demo and I thought it was a VERY BIG radial starting outside!!! The noise was mind numbing.The demo flight was launched from a sloping rod/pylon and the speed must have been in the 200s plus. The model was a delta, about 3 feet span and the guy flying it had, obviously, done it many times before. Ultra high speed low passes, upright and inverted, one of the latter nearly bringing it to an abrupt end when he made fin-top contact with the runway!!
Haven't seen or heard of them for many years so maybe common sense prevailed!!
Rgds
Bill
Thread: Wiggly amps, NVRs and motors?
01/07/2011 17:33:00
Update to the update.
Gentlemen, thank you - your remote diagnosis would appear to be spot on. I have just rewired the original NVR and reconnected to the motor. Switch on, press the green and all working as advertised!!
It would be nice to think that I understood the technicalities involved but my understanding of electrics came to an abrupt halt at my first electrics lesson at Air Sig's School, when our instructor opened with "There are TWO types of current flow - Conventional, Positive to Negatve and Electron, Negative to Positive" Being a bit of a dullard, I had to ask, "Which is correct?" Response was "I can't tell you!!" Thereafter, wiggly amps remained a closed book!
Again, thank you
Rgds
Bill
 
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