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: Hardening gauge plate (O1)|
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|
Here's a strange one from my inbox today:
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|
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
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.|
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|
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'?|
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.|
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!
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'?|
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.
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.
Thanks Paul. That should work , didn't think of it. Compartmentalised thinking on my part - boring head is a milling tool...
Yes, I could make a cutter but I'm a lazy b*st*rd, and if I could buy off the shelf it would be easier. Also I wanted to know if if such things exist for self-education. Strange as it must seem to those who have spent a lifetime in engineering, I didn't even know how screw threads were made for the first fifty years of my life. I'm an old dog trying to learn new tricks.
I can make an internal bore to H7 with a boring bar, but for small diameters it's easier/quicker to drill and ream. I can turn 10mm externally accurately sure enough, but I was wondering if there was tool, analogous to the internal bore reamer, which would make the process faster and less prone to error.
Edited By Robin Graham on 18/08/2021 01:57:56
I want to make some parts which require turning thin discs with 10mm 'spigots' - I don't know if that's the right word, but to give an idea:
Ignore the 'features' on the spigot which are due to lapses of attention . At the moment it's 11mm so I can turn them out. I was listening to a jolly interesting murder mystery at the time, and sudden plot twists lead to involuntary muscle movements. That's my excuse anyway.
My plan is to turn the spigot to size (I'm looking for an easy push fit in an H7 hole), part off a slice, then do another on the same bar and so on. As I have to do a few I was wondering if there is a tailstock tool that could form the 'spigot' accurately in one go if I rough turned to say 10.5 mm.
To give an idea of what I have in mind there are woodworking plug cutters like this:
Does anyone know if metalworking tools are available for this purpose? I suppose I could make something myself, but I'm reluctant to believe that this wheel hasn't already been invented.
Edited By Robin Graham on 18/08/2021 00:33:59
|Thread: Dipping a toe in TIG - what do I need (apart from skill)?|
Thanks for replies.
Noel, I have read and replied to you PM - thanks for your offer of assistance.
After reading and digesting all replies I think that I might be dipping my toe in waters much deeper than I first thought. But I am much more informed now, and in a better position to make a decision.
Thanks again, Robin.
I have a Parweld 160A MMA inverter welder which was marketed as MMA/TIG - it has a 'lift TIG' setting. I'm now thinking about trying to teach myself TIG using this machine as a power source and I want to cost it up.
I've done a fair bit of searching and have found plenty of stuff about technique but haven't yet found a basic starter's guide to the equipment needed.
Any help would be much appreciated.
Edited By Robin Graham on 09/08/2021 00:08:08
Edited By Robin Graham on 09/08/2021 00:09:37
|Thread: Drill powered nibblers - buying advice sought.|
Thanks for replies. Perhaps I should have said that that my project is to make a sort of bbq/smoker thingy out of oil drums and scrap sheet metal, so I need to cut holes for vents, tubes etc in both the curved surfaces of the drums and the flat ends. I didn't frame the question as 'what's the best way from here to there' because I wanted opinions specifically about nibbling tools. Generally, when I buy a new tool for a particular job I have an eye on its usefulness for other things.
I have piercing saws, which are great for what they do, but wouldn't work here because of the geometry. I also have a jigsaw, but it's my second most hated tool (first is the angle grinder*) - cutting anything thin without support, which would be difficult in this case, doesn't work well.
I'm encouraged to go ahead and try a cheapy after following John Haine's link to mikesworkshop.
A lot of the negative comments both here and elsewhere concern the pesky crescents. I don't think that would be a problem for me because I have a scarily powerful vacuum machine which would whisk them away.
Thanks again for replies,
*Angle grinder phobia - I have a groove in my left kneecap thanks to a momentary lapse of concentration. A&E, much blood, and a new pair of trousers ruined. Not only in the knee area.
Edited By Robin Graham on 02/08/2021 01:19:15
I want to make some curved cuts in 1.5mm mild steel sheet. It looks like a nibbler might be the tool of choice, but I don't want to pay £££s for a dedicated machine, so I've been looking at drill powered devices.
At the bottom end I found a TOOGOO machine for £12, which does seem too good to be true. At the top end there is the Australian-made CaNibble at £50. In between there are many offerings including one from Axminster at £36.
With the exception of the CaNibble all these tools look the same - I know that you gets what you pays for, but on the other hand I also know that identical items are marketed at widely different prices on Amazon and elsewhere.
Does anyone have any experience with these tools?
Edited By Robin Graham on 31/07/2021 23:51:14
|Thread: More Q's about surface finish.|
Thanks for replies, and apologies for not getting back to this sooner - my wife has taken on a foster dog so I've been in woodworking mode making stair gates. C'est la vie!
William - many thanks for the info about Whitaker rings. I'm not convinced that's what going on here though - brass, very light cuts (~10 thou) slow feed. But maybe - and valuable info even if it isn't.
Bob Stevenson - I was initially sceptical about 'stages of resonance', but changing the spindle speed from 550 to 700 rpm gave different 'zones':
and returning to 550 gave results broadly similar to my first photo:
So it's mechanical. I think I understand what's going on now.
On the optical effects, I found, unsurprisingly in retrospect, that the 'spectrum' was very much dependent on camera and lighting angles. Thanks Martin.
I doubt that I can get much further in understanding optical effects without specialist kit - a trichroic beam splitter would be an absolute minimum requirement I expect. Sadly , I haven't got one.
I should just be happy that I can get this finish on a mass-market hobby lathe.
Edited By Robin Graham on 30/07/2021 01:21:13
Edited By Robin Graham on 30/07/2021 01:28:35
|Thread: is a belt sander any good for hss tooling|
My take on this is based on experience with Sorby Pro-Edge, but may be useful.
Does anyone think this is a viable method for maintaining tools (and drills with a drill jig).
Yes, I frequently use the Sorby for this sort of thing. I can't see why the cheaper Clarke linked to wouldn't work, for HSS at least, given suitable belts.A caveat is that the Clarke runs quite a bit faster than the Sorby - 13.5 against 3.7 metres per second. I don't think that would be a problem for HSS (bench grinders run at an even higher surface speed), but it would be too fast to be comfortable for carbon steel.
Do the belts wear out too quickly to be useful?. I know how quickly wet n dry paper loses its edge unless used with soap n water.
No, they last surprisingly well.
My own experience with wet 'n' dry is that if used dry it clogs well before it lose its edge. My take is that using lubricant is more to do with mitigating the clogging problem than preserving the edge, but I may be wrong. Belts also clog before they become blunt, but can be restored to near pristine condition with a latex cleaning block such as this .
i think i ve found some answer, you need 760mm belts of zirconia or ceramic (ca £5 ea)
Personally, I've found alumina belts OK for most things - they don't last as long as zirconia, but are very cheap. I've never tried ceramic, so can't comment, but if you want fancy, 3M trizact are the dog's and last for ages - they seem to be available in most sizes.
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