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Member postings for Robin Graham

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

Thread: A workholding question.
24/10/2021 23:39:39

Thanks for replies. This is what the slot looked like after the first pass (2mm DOC):


It seems that the work wandered clockwise:



I was cutting away 'front to back' in this view with a 2-flute slot drill - so conventional milling on the left hand side of the slot. I guess that makes sense - the bit was trying to pull into the work.

The reason that I tried this setup was that I'd used a similar arrangement for turning and facing on the lathe and that works well. Presumably that's because a it doesn't matter if the work slips a little around the rotational axis when the the cutting force is applied. A different result when milling though!

From replies it looks that I don't need to buy or make an expanding mandrel, which is good news. The 'bolt on' approach should work. I can make a through hole, as I said in my original post.

With the benefit of hindsight I should have done the milling before the turning/parting as suggested, It's not the first time I've painted myself into a corner and had to devise an escape route blush.








Edited By Robin Graham on 24/10/2021 23:41:14

22/10/2021 00:59:21

I think I may know the answer to this, but would like to check before trashing any more brass.

I want to make a number of hubs like this:


That's a mess I know, but it was a proof of principle exercise, not intended to look pretty!

I set up the 'proper job' to cut the 3/16" slots like this:


The brass disc is held against the steel stub in the chuck by two sided adhesive tape and tailstock pressure. The work moved with consequent knackerment.

There's no reason why I couldn't drill the disc through centrally to take an expanding mandrel, but I haven't got one and it would cost me 50 quid to buy. I think that if I just drill the disc and turn a close fitting mandrel with a shoulder and threaded end to allow me to clamp it down on the shoulder with a nut and washer, dispensing with tailstock  support. it should work. But I'd like a sanity check before trashing any more (expensive) brass!





Edited By Robin Graham on 22/10/2021 01:00:24

Edited By Robin Graham on 22/10/2021 01:03:10

Thread: Workshop lighting / energy costs
15/10/2021 02:08:53
Posted by Andrew Johnston on 14/10/2021 11:24:42:
Posted by mgnbuk on 14/10/2021 10:56:38:

Why do you reckon that they are the same ?

7,860kWh is the same quantity as 7.86MWh. Note the change from comma to full stop.

The bill for 7.86MWh at 15p per kWh would be £1179.


Thanks for the sanity check Andrew, and also to Journeyman John earlier. I honestly thought I might have lost the plot what with those pesky decimal points and powers of ten.

Apologies if I muddied the waters by talking in MWh - that was because I was thinking ballpark figures out loud and it seemed an economical way of expressing the quantities to two significant figures.

It's tough thinking about mega and micro things from a human perspective. What is a Megawatt? My point of reference is a one bar electric fire - that's a kilowatt which I can see and feel. But multiply it by a thousand and I have to rely on arithmetic and imagination.

The last time I heard (maybe a week ago) wholesale gas for delivery in November was trading at 220p per therm. That's about 7.5p per kWh but even after the hike my supplier is asking me for only 6p /kWh. So when the price cap is adjusted next spring I'm expecting a hit.


Edited By Robin Graham on 15/10/2021 02:10:57

Edited By Robin Graham on 15/10/2021 02:11:53

14/10/2021 00:29:28
Posted by J Hancock on 12/10/2021 08:28:23:

2.7MWh/ annum ! Wow , that's some workshop you have there.

Errm ... that's projected total house / workshop consumption. Ofgem give the average electricity consumption for a 3 bedroom house as 3,000 kWh / annum - which is 3MWh / annum in my head. Have I gone wrong there? Or was that intended ironically?

The problem is my electricity supplier is projecting 7,860 kWh (or about 7.9 MWh by my reckoning) per annum based on past usage.

I think I can do better!



Edited By Robin Graham on 14/10/2021 00:33:29

Edited By Robin Graham on 14/10/2021 00:35:54

12/10/2021 01:46:08

Well, it's all been a bit of an eye-opener. I've now accumulated data over 11 days during which time I've spent five or six evenings in the workshop - the pro tem adjustments I've made are hardening myself off ( I actually work faster and more efficiently with the workshop at 17 degrees than the 21-22 in which I'd been luxuriating), and directing light to where it's needed rather than flooding.

The results so far suggest that my house + workshop electricity needs should be satisfied by 2.7 MWh / year in contrast to the 7.86 MWh /year estimated by the electricity supplier. That translates to about £100 saving  - an eighth of a roll of gold wallpaper or 20 carbide inserts -  per month, depending on how you personally reckon it.

I can make further improvements by cladding the ceiling with something painted white as suggested - I have some hardboard as Dave Halford advises, but even cardboard (thanks to Amazon, lockdowns, and my reluctance to bin anything) would do.

I don't want sell the bandsaw and go back to hand sawing as Martin recommends because I think that might put an unnecessary burden on the Ambulance service, but it's an idea I suppose.

On Peter Greene's point about the reliability of LED's I too have found that for the most part the drivers fail before the LED's themselves. I posted a question about this some time ago and someone (MichaelG I think) suggested that poor quality light switches might be a factor. I have replaced my (old) house switches with MK versions, and it's made a real difference.





Edited By Robin Graham on 12/10/2021 01:52:00

Edited By Robin Graham on 12/10/2021 01:56:34

Edited By Robin Graham on 12/10/2021 01:59:31

06/10/2021 02:42:40

Thanks for an (ahem!) illuminating discussion. Unfortunately painting the ceiling white isn't an option if I want to remain married. My wife has fantasies about turning the cellars into living space when my love affair with the lathe &c has run its course. She likes the raw brickwork.

Reading replies I think my best option is to change to LED's and make the light more focused on important areas. I've certainly found that LED bulbs seem to be subjectively 'brighter' than fluorescents with the same nominal lumen output.

Further measurements suggest that our background usage (measured overnight with everything turned off except the fridge and freezer, TV's/computers sleeping and a single light) is 225W. I guess that's mainly the fridge and freezer, which is pretty good I reckon.

SoD makes a good point about the small things adding up with the 'high ticket' / short duration appliances being less important. I'm trying to convince my wife that it's still OK to use the electric kettle and the dishwasher! And convince myself that it's still OK to use the 2Kw lathe - actual turning time is a small fraction of workshop pottering time. With those lights on.

Workshop heating is the next thing to attack. I've been using 3kW electric fan heater, blissfully ignorant that I was using in an hour what the rest of the house uses in a day until I made these measurements.








Edited By Robin Graham on 06/10/2021 02:46:07

Edited By Robin Graham on 06/10/2021 02:48:23

Edited By Robin Graham on 06/10/2021 03:04:28

05/10/2021 01:25:21

I've not worried too much about my energy costs, high as they are, until now . I live in an old and poorly insulated house and thought that's just how it goes. But I'm sure I'm not alone in having had an email advising of a substantial hike in prices - around 30% in my case. That made me think.

My energy provider estimates my annual electricity consumption at 7,857 kWh. That translates to about 900W continuously, which I thought was reasonable.

As I've been unable to get into the workshop recently for health reasons, I thought I'd make a graph of background household consumption:



The slope until the sudden upturn at the end amounts to about 325W. The upturn was coincident with me going down to the workshop and leaving the lights on.

I was really surprised by this - I'd thought that my workshop was a tick on the back of overall household electricity costs, but it seems that it is in fact dominant. It seems odd to me that a continuous 325W is enough to run a house with an electric oven, microwave oven, electric kettle, washing machine, dishwasher, two computers, two TV's and lighting. That's three and a bit of the old incandescent lightbulbs! But that's how it seems to be. I'd be interested to know how others fare.

At the moment my workshop is lit by four T8 58W fluorescent tubes:


which between them give around 20,000 lumens I think. I had a look at LED tubes, but it seems that to get the same level of illumination wouldn't actually save me much. Maybe I could do better by more strategic placement of lighting. Any advice would be welcome.


PS - please don't nag about the hanging sockets, I know and I'm working on it.





Edited By Robin Graham on 05/10/2021 01:47:04

Thread: Hardening gauge plate (O1)
03/10/2021 23:56:20

Thanks for replies and apologies for not getting back earlier.

From the replies it looks like I can carry on brine quenching without too much fear - the the thickest section I'm using is 3mm by maybe 40mm width. I had worried that I was on the threshold of distortion/cracking disaster, but it seems not.

I have Tubal Cain's excellent book , but in his treatment of quenching he seems (for the most part) to talk about high carbon steels in general. However, in the last paragraph of p32 of my edition he says:

"For model engineers, therefore, we can say that in general water will serve for our needs, but brine is preferable when ultimate hardness is needed. Oil should be used for milling cutters and for gauges or hardened jigs - preferably using the proper oil-hardening steel for the latter as it is formulated to avoid distortion [my bold]."

My assumption was that this steel (eg O1 I guess) was optimised for oil quenching and wouldn't perform as well as 'normal' tool steel (eg silver steel) when water quenched. Otherwise, why not make all tool steel to this formula? I'm still not clear about that!

No-one has commented about Sparey's suggestion of 50% suds as a substitute for whale oil; If I get time (unlikely!) I'll give it a go and report back.




Edited By Robin Graham on 03/10/2021 23:57:19

Thread: Is there such a thing as an 'external reamer'?
03/10/2021 00:20:59
Posted by Tony Pratt 1 on 30/09/2021 12:01:46:

So Robin Graham, was this ever sorted?


Apologies for failing to report back on this. What happened was that I found that the repeatability of the QCTP was indeed much better that I had supposed as you suggested - perhaps not half a thou, but good enough. So I ended up turning in the normal way, with the aid of the DRO and a bed-mounted carriage stop.

This topic has had over 50 replies and I can't acknowledge every contribution individually, but I have read and been informed by every one - my thanks to all who have replied.


Thread: Hardening gauge plate (O1)
28/09/2021 01:42:10

Sometimes I make edge tools from gauge plate which I think is the same thing as O1 oil-hardening tool steel. I've tried quenching in motor and cooking oils but (according to my hardness testing files) have never got above 50-55 RC. I can get to 60-65 RC by brine quenching, as you would do for silver steel, and I seem to have got away with it so far.

But it's not the right way to do it and that worries me!

I was browsing through Sparey (The Amateur's Lathe) today, and lit on his recommendation to use a 50:50 'soluble' oil / water mix if, like me, you've run out of whale oil.

I'm wondering if anyone has tried this. I'd also be interested to know what oils other folk use - I know that there are commercial quenching oils out there, but they seem very expensive.


Thread: Yet another scam
21/09/2021 23:15:04

Here's a strange one from my inbox today:

Dear null,

Great news! We’ve automatically upgraded your 50 GB iCloud storage plan to iCloud+ at no additional charge, and you can now share your subscription with your family.

Maybe it's genuine - I have an iPhone and Apple abstracts 79p from my bank account every month, which I think has something to do with iCloud. But the salutation is strange, and doesn't give me a warm 'I'm part of the global Apple family' feeling. Or even a tepid 'I'm a human being' feeling.

I don't think I'll click on the 'find out more' link though.

char *Robin;  /*(aka null)*/

/* I'd like to know how this happened - any computer language buffs out there? */

Edited By Robin Graham on 21/09/2021 23:16:52

Edited By Robin Graham on 21/09/2021 23:23:27

Thread: 9/32 hex steel bar
05/09/2021 00:57:05

Not sure if you meant [(excellent price) list] or [excellent (price list)] Michael, but it's certainly an unusual price list (both ways) in that they base prices on what they paid when they bought it, rather than current value. That policy leads to anomalies such as 2.5" round steel bar being 13% cheaper than 2.25" per unit length. Worked well for buying brass when copper prices went through the roof!

Mal may well find that that the price/availability of 9/32" hex is based on a half metre length which has been sitting on the shelf for years, but worth a try.



Edited By Robin Graham on 05/09/2021 00:57:41

04/09/2021 00:37:33
Posted by malcolm conomy on 02/09/2021 05:47:13:

Hello from Australia,

I am trying to source 9/32 hex or 3ba hex bar, for a batch of small nuts I need to make. I need about 30 - 1 metre lengths or longer. Does anyone know of supplier in the UK who can supply.


Live Steam Models down the road from me (in the UK) list 9/32 EN1A hex at £1.15 per metre. I doubt that they would have 30 metres in stock as they are a small outfit, but presumably they have a supplier. Might be worth giving them a shout.


Thread: A strangely coloured flame.
02/09/2021 02:36:09

The council here in the Derbyshire Dales has suspended the weekly collection of food waste for composting because of a shortage of lorry drivers. We are supposed to bag up food waste to go into the landfill (non-recyclable) bin, which is collected fortnightly. It's been a bit of a problem because the kitchen bin doesn't get processed properly, becomes a bit stinky, and flies are attracted. I don't like flies in the kitchen.

My wife suggested that we could burn the food waste. I was enthusiastic, because being still a boy at heart I like burning things just 'to see what will happen'.

To get to the point - having been given a licence to burn I bunged a fat and charcoal encrusted piece of aluminium foil from from the grill pan into the wood burner. It produced a weird lime-green flame. I had a look and found that aluminium foil is 0.05% copper, so obviously I tried burning a ball of clean aluminium foil under the same conditions, but no hint of green.

Any suggestions? Arsenic gives a blue flame which combined with the yellow of the wood flame might give green. That's a bit pessimistic though.


Thread: 5 Rotary Table/Tailstock/Chuck Kit Info/Questions
02/09/2021 01:16:12

I have a 6" Vertex RT which I use with my WM14 mill - about the same size as the SX2, perhaps a bit smaller:


That's obviously an - ahem - suboptimal setup, but shows what can be done in the way of fitting quarts into pint pots. The work was ~1" diameter and the tool mounted in an ER25 collet chuck. I didn't have problems with headroom - it was the size of the table which was problematic. Anyhow it worked:


The chuck is a SC 3-jaw, which lives pretty much permanently on the RT. It works for most of what I do. I can't see what advantage a 4 jaw SC would bring for RT work, but maybe I'm missing something.

The RT has a 2MT bore and I centered the chuck by turning down a 2MT soft arbor to fit the back end of the parallel chuck bore. This has the disadvantage that it blocks the RT bore, but on the plus side it's proved pretty accurate - better than 0.03mm TIR . It's a good (Rohm) chuck though, which may have something to do with it.


Thread: Is there such a thing as an 'external reamer'?
28/08/2021 03:07:36

Thanks for further replies. I realise that this is getting into 'by the time I'd written/read all these posts I could have made a hundred' territory, but for me the point of making stuff is not only the finished part, but also learning about tooling and techniques. When I started out I didn't even understand how metal could cut metal, but now I know about HSS and Carbide and Rockwell scales and all that stuff.

Pause to polish fingernails on lapel.

Howard - I once cut a 2" round steel bar with my muscles and a hacksaw. Never again. It looked like it had been chewed through by a mad beaver. I bought a bandsaw.

Noel - I looked at rotabroaches, but I think they are designed with the OD in mind, and anyway I I think the shank diameter is too big to mount in a tailstock chuck. Thank you for checking though.

Michael - food for thought perhaps. Though from your somewhat gnomic reply I'm not sure what exactly you have in mind.

ega - I had a look at your album. Nice work, but I'm not sure that in my case the effort of taking off the saddle to drill for the stop would be worth it as I have a digital scale.

Dave S - I've bookmarked that, An interesting 'DIY' approach.

Tony - half a thou repeatability for the QCTP would be fine - I'm astonished actually, I'd been thinking more like 5 thou, I'll have to measure.




Edited By Robin Graham on 28/08/2021 03:08:50

Edited By Robin Graham on 28/08/2021 03:15:39

Edited By Robin Graham on 28/08/2021 03:17:22

Thread: More Q's about surface finish.
28/08/2021 02:02:23

Thanks Michael. The chap who made that video is a very good teacher I think.

My problem isn't so much the theory (my PhD project involved a scratch built magneto-optical spectrometer, so I got to know a bit about diffraction gratings) as setting things up to measure angles etc in my ramshackle workshop.

A pleasant 7 minute watch though!

Regards, Robin

27/08/2021 00:43:00

Thanks Michael, that's an interesting video.

I have pursued this a little further by setting up a primitive apparatus involving various clamps, a red laser pointer and a baking-parchment screen. I can see fairly well defined maximums and minimums. They're smeared of course, but I suppose that shows - well something! I'll refine my apparatus and see if I can make any meaningful measurements.

Pointless in some ways perhaps, but entertaining.


Thread: Is there such a thing as an 'external reamer'?
26/08/2021 00:20:28

Apologies for not getting back to this and replying to further contributions sooner - I've been bad in health recently and unable to face going down to the dungeon (aka workshop), so I've been enjoying a pampered superterranean existence.

I have digital scales on my lathe, so in principle I could use the cross slide scale to achieve the reproducible accuracy I'm aiming for. The reason that I was wondering about tailstock tooling is that I need either to (a) change tooling to part off each item, or (b) remove the stock from the lathe to saw Obviously (b) would lose reference, and I worried that (a) would do too. I normally use a Chinese QC toolpost:


but I don't know how accurately it relocates the tool after a change. Perhaps I should measure, or maybe someone can tell me.

I'm intrigued by the idea of a cross-slide stop, but at the moment I'm not sure how I could implement one on this machine. I have made a longitudinal stop, and, despite having scales, it's paid make the time of making many times over when doing repetitive work

In the light of Dave S's post, I'll try a home-made tailstock cutter just to see.


20/08/2021 22:43:53

Thanks for further replies. I have 12 to do, so just into double figures, hence the desire to look for a 'mass production' method. I was hoping that there was a (modestly priced!) off-the-shelf tool which would do what I want. It looks like the tools John Reese linked to are what I had mind but, as Emgee points out, not modestly priced! I guess I could make something similar out of silver steel but after reading replies and fiddling about a bit with a boring head I've come to the conclusion that for a dozen pieces, to get the sort of tolerance I want, I'm best off just turning the the spigots normally. It takes me maybe half an hour per piece, but I'm time-rich.

Thanks again for suggestions and apologies if this has been a time-wasting thread - but sometimes one has to travel down dead ends in the learning process.


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