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Member postings for norm norton

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

Thread: is there an easy identification test for Nickel and Chromium ?
27/11/2020 15:10:01

Michael

Nickel will readily come off with an electric current and a mild acid bath giving a green/blue solution (reverse of nickel plating). Just start the process to see if the surface suddenly brightens.Chrome will not come off in mild acid.

My experience from stripping chrome and nickel off old parts.

Norm

Edited By norm norton on 27/11/2020 15:10:41

Thread: Strange Word...
14/11/2020 19:28:07

Strangeness might be a personal interpretation of what we see wink

Crossslide is a compounded noun; originally cross slide, then cross-slide but then crossslide might be a compounding too far.

Thread: Help - Harrison 140 lathe
30/10/2020 10:13:13

Lead screw dial will tell you when the metric screw cutting can be re-engaged.

Thread: Help - 6BA Socket head cap screws
29/10/2020 19:39:57

ba-bolts

EKP

Thread: Help - Harrison 140 lathe
29/10/2020 17:26:07

Hi Steve

The 140 is a metric lathe, with a metric leadscrew. The gearbox will give metric screwthread pitches using the set of 'big' gears described in the manual. Register on this Harrison Forum where there are manuals, etc. With a special set of 'big' gears you can cut exact imperial pitches, but the leadscrew has to stay engaged.

I have a 140 and have sorted out the imperial gear set so ask me if you can't find it on the Harrison forum.

Norm

p.s. it is a superb lathe to use so you have done well to get one.

Edited By norm norton on 29/10/2020 17:29:49

Thread: Locomotive wheels
05/10/2020 10:27:17

I wish I knew what a 5" Salisbury was, but I apologise that I do not. If it is a very early engine the designer might be replicating a simple tread.

If you plan to run it on a club's 5" track it will be very worthwhile adding the cone angle, as they run better, and taking care over the gauge and back to back of the flanges, i.e. do not make them too thick. The 5" track should sit just at the point where the coned portion rises into a radius before the flange.

Type 'GL5 wheel standards' into Google to see the generally accepted UK standard for 5". It will also come up with other profile discussions.

As for the wheel/tyre groove you do not often see this on full size engines. You really need a photograph of a Salisbury to see how it might have been finished.

Norm

Thread: Walton broken tap extractor
01/10/2020 09:32:13

Thank you for showing it Henry, never seen one before.

Please can I have one in 10BA?

Thread: The repair shop
01/10/2020 09:30:09

Why do they always blow the dust off the job? Bad, bad idea. Blame the Producer who thinks it looks good.

Thread: Awstin or Ostin
30/09/2020 20:41:44

'Ostin' seems the more logical pronunciation. It follows the same as Austria and Australia, but austerity can go two ways?

"Awstin' sounds the more affected, and 1930's, but might it be a regional dialect?

Thread: 5BA Threads
29/09/2020 09:19:49
Posted by Michael Gilligan on 28/09/2020 20:36:23:
So presumably I am not included in ‘people’ angel

My apologies, you are very 'people' (and emoticon saintly)

At least you gave a sensible response to the OP and discussed his subject. Having re-read the thread I don't know why I thought my BA vs. metric statement was in any way appropriate; oh well, apologise rather than delete blush

28/09/2020 18:34:14

What people are failing to acknowledge is that the BA range of sizes, especially in 4-14BA, and based upon metric principles, is vastly better than the Metric system has contrived to offer.

Tongue in cheek but I mean it

Norm

27/09/2020 13:56:14

BA Bolts have one of the biggest ranges, and he makes a lot of his own.

Thread: Left Hand Milling Cutter
09/09/2020 22:06:59

They do exist, found these from America, bit too expensive to import, so might keep looking. 2AAAOSwNhpa55Zd">link

 

 

Edited By norm norton on 09/09/2020 22:08:06

09/09/2020 21:43:52

Pleased I have caused a little bit of enjoyable thought Some interesting feedback, thank you.

Responses in reverse order.

-touch a clockwise rotating cutter on the edge of a round object and that object will try and rotate counter-clockwise, i.e unscrew upward.

- Fly cutters by definition have a moderate radius and this means a thumping wallop each rotation.

- Putting a small piece of work in a Stevenson hex ER block, and rotating that in a chuck manually, produces errors of at least 0.010". Been there, tried it, a mess. I am looking for 0.0001" in the vertical otherwise that small hex I show in my photo has all manner of irregularities in the horizontal land around it.

-The above is why working with the rotary table horizontally is better by keeping the cutting tool at a fixed depth of cut as it runs in the X or Y past each of the six faces in turn. Hence a perfect face around the hex sides.

- A small, 6mm, three flute carbide cutter is the ideal cutting tool for the brass of this size. I just wish the Chinese made left hand cutting ones!

- I like Neil's suggestion and it is what I thought I would do. Make a 6mm dia cutter from silver steel, mill cut a pair of teeth with rake and relief, harden to a straw temper, then diamond hone the tips

Thread: Steam Flow through a fine orifice
09/09/2020 21:15:35

Steve, thank you, your comments are helpful in that you have not challenged anything I am doing. I shall have to read a little more elsewhere as I would like to understand whether my limited understanding from 40 years ago (viz: a CFO is a pure hole with no length and the critical flow point is related to the speed of sound in that fluid) is correct or not.

To help others who are wondering what I am doing with this safety valve, it is a proven design that adequately discharges the necessary steam, but I have changed the holes in its vent cap for appearance only and I want to understand whether, theoretically, this may adversely affect its safe operation. I have also made the single row caps and I can, and will, compare the two versions in an actual test in a few months. For now, the feedback above, gives me confidence that the modifications will be ok.

Norm

Thread: Left Hand Milling Cutter
09/09/2020 14:53:15

I often have small work items (e.g. valve blanking caps) that I want to hold on the rotary table in order to machine a square or hex head on the top. These often have a thread on the other end and so easily screw into a threaded mandrel that I can grip in a collet chuck on the rotary table. They are short and offer little other surface for gripping.

valve cap.jpg

The problem is that if the mandrel is held vertically, and you touch the work with a conventional (clockwise) rotating tool, the work item will unscrew from the mandrel. Ahh, I thought, I need a left hand spiral milling cutter to be running anticlockwise. But there aren't any, why not? There are LH taps and drills. The only LH spiral milling cutters are designed to turn clockwise and the spiral forces the swarf and hence work item down on the table.

So far I have got round this by setting the rotary table vertically, the mandrel thus horizontally, and now a clockwise cutter drives the work into the mandrel. But the bulk of the rotary table gets in the way of the milling head.

The thread on the work is cut first on the lathe, then the item is parted off. I cannot see that there is another work sequence to let me cut the hex first on a longer piece of stock.

Any thoughts people? and why are there no LH cutters I can find? I shall have to make a simple one.

Thread: Steam Flow through a fine orifice
09/09/2020 14:22:05

Thanks, reassuring answers regarding the conclusion that as long as I have a greater total area, the actual diameter of the holes does not matter (seems counter intuitive to me, is this true even with a large number of (e.g.) 0.1mm dia. holes? which then create very long, narrow cylinders? but lets go with it for now).

I though that if a fluid flow system got anywhere near to criticality then the pressure drop rose rapidly to become a flow limiting absolute. I can't see that these vent holes could work if they were anywhere near that. I clearly need to know the volume of steam generated per second and then calculate the steam velocity.

I am trying to work out the implications of your comment Gareth. The boiler will be 6 barg (90psi). Perhaps in a safety valve most all the pressure drop is across the ball to seat gap, and this gap increases as a greater volume of steam has to be released. Meanwhile, the pressure drop across the vent cap is only a small fraction of the ball to seat one and thus the small holes stay away from criticality?

08/09/2020 17:07:35

This is a bit of a specialist question, but perhaps a fluid flow specialist might know the answer, and others might like to speculate.

I have built a pair of safety valves for a 5"G locomotive, and to make them more prototypical in appearance have drilled the vent cap with two rows of very fine holes (18 off 0.9mm dia. and 18 off 1.2mm dia.), rather than a single row of larger holes (12 off 1.7mm dia.). Now the cross sectional area of my two rows is substantially greater than the singe row, but I am concerned that the diameter of the holes is such that they act as critical flow orifices. However, if the flow through the single row is not supersonic, it cannot be so in the two rows. Or am I missing something?

I have used this website that provides a calculator https://www.tlv.com/global/TI/calculator/steam-flow-rate-through-orifice.html

but if I plot the data for smaller and smaller orifices I still see a liner flow vs. area response, so has this calculator allowed for a critical behaviour? I don't think so but what do others think?

I appreciate that I could answer this if my physics knowledge included Reynolds number and fluid physics, etc. but it dosen't. Anyone have a quick answer? Sorry I don't have a ready number for the mass of steam that the valves have to shift other than an estimate that we are talking about 10 to 20kW of thermal energy generating that steam.

Norm

Thread: David Noble
25/08/2020 10:05:22

Dave Noble is around and active. I don't think he has a connection with The Steam Workshop, nor am I aware does Doug's son. Dave has cut out all his previous, extensive manufacture of engine and wagon parts, but last I spoke to him he was continuing with the water gauges. He did supply several retailers, try Blackgates first.

Thread: Hardware for the shop
22/08/2020 10:13:15

Jeremy,

Could you get on with just having all Metric screws and bolts in your stock, and then buy any special UNF/UNC/BSF/BSW/BA only as and when needed? I would now recommend any younger newcomer to convert any drawings to metric and certainly the fittings.

I do like imperial, but I have BSF/BSW in zinc and stainless for motorcycles, and 26CEI for engine parts. Then an awful lot of BA in brass, steel and in hex, reduced hex and slotted. My Allen Head and Grub Screw box contains BA/BSF/Metric sizes in steel and stainless. And then, of course, I have a whole range of Metric screws and nuts in zinc mainly to cover the sizes above BA. And I still end up turning custom screws and nuts for steam engines which need 32 and 40 TPI.

It's all a bit too much really. Plan all jobs in Metric and stock those only. Buy good sets (Tap and Die Co) of all the other thread forms for the specials, and you will be fully equipped.

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