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Member postings for Calum Galleitch

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

Thread: Engineered fuel prices
02/08/2022 18:43:43
Posted by Grindstone Cowboy on 02/08/2022 14:51:26:

I'm not sure what the price of autogas (LPG) was before the increases, but I noticed yesterday our local Morrisons had it at 78p a litre, which seems to be a huge difference to petrol and diesel.


The density of a litre of gas is obviously different, but generally the UK is in an odd situation with respect to gas: we land a lot of gas that goes to Europe, and since a lot of Europe's gas is currently being restricted by Mr Putin, Europe is trying to get more from us - but we can only shovel so much through the pipelines in a day, so we often have gluts from day to day. The spot price (for delivery right now) has been swinging around all over the place in consequence.

Thread: Will the lights stay on this winter?
29/07/2022 15:06:50

The energy market is complex and there are no simple solutions.

The profits being taken, although obscene, are a drop in the ocean; divide them by the number of people in the UK and it's a few pounds per head - your energy bill is mostly paying for energy.

Energy is sold on an open market. The way the price is determined is complex but at the end of the day a wind farm sells its energy for what it can get, and if the price of energy is high they earn lots of money. Your 100% renewable supplier buys that wind farm energy on the open market and resells it to you.

The modern grid is actually far more resilient than it used to be - last week's heatwave would have knocked the grid over in previous years, as we lost essentially anything that requires air cooling. But the total capacity desperately needs increasing, and transmission needs bulked up: often wind energy generated in Scotland can't get where it needs to be because there is no transmission capacity to get it to the south of England, so wind turbines stand idle.

Thread: Grinding brad points on long series hss drills
24/07/2022 11:50:22

The purpose of a brad point is to create a clean entry hole in soft material; it has no bearing on straightness and I'd guess probably makes it worse.

Drilling an accurate hole in 300mm of wood is a challenge; some more information about the workpiece and setup might be helpful. Generally, though, the advice would be to start off with a stub drill one size under, ream to size, then step up drill lengths. The drill will still wander but it will get progressively worse instead of veering off sideways from the start.

If that isn't sufficient, you will need to leave the world of twist drills behind and investigate things like D-bit drills and gun drills.

Thread: How to machine out a metal channel by hand?
24/06/2022 20:15:19

What glue did you glue it in with?

Thread: Replacing a 24V AC machine lamp
19/06/2022 09:15:39

> I think the underlying problem that you have is the inadequate quality of contact in that type of holder

Yes, I think you're right - both the lamp itself and also the wires connecting to the switch are both in pretty dubious state. Nowadays when you buy these lampholders they tend to come with wire pre-attached, but mine just had a push-fit, one of which has failed entirely.

Peak4's link above looks spot-on, so I have ordered one and hopefully that will last another twenty years!

18/06/2022 19:48:00

Yes, the lamps themselves are easy - it's the holder I'm looking for, or if the holder can't be found a replacement for the whole assembly.

Lorries/campervan electrics are DC and seem to have all gone over to LED already - I did think that was the obvious place to look but I couldn't see anything obviously useful.

18/06/2022 18:32:35

My lathe has a lamp:

screenshot from 2022-06-18 18-05-53.jpg

The lamp used to work, then it made a fizzing noise and stopped working. I took the lid off, removed the bulb (a G6.35 halogen), and ascertained that it appeared to be intact. Noticing the legs were covered in what can only be described as grime, I wondered if some sort of deposit was blocking the healthy flow of electrons. A rinse in vinegar and an overnight dry, I popped it back in, and, success! A working light.

For a few days. Then once again a fizzing sound followed almost immediately by darkness.

This time I thought I had better take it to bits and check it properly, which I did, and found some very old and tired looking wiring. And I found a lampholder, looking like one of these:

screenshot from 2022-06-18 18-04-46.jpg

The one I have is somewhat elderly, and along with the wiring I think it should be pensioned off. Which leads me to the problem: what to replace it with? I am stuck (well, do not want to replace) with 24V AC. As far as I can see that pretty much rules out LED solutions as there doesn't seem to be anything commercially available that would be a drop-in replacement. The lampholder itself doesn't seem to be available any more (at least in quantities less than 100), and the reflector is 65mm, not the 50mm standard used in household bulbs.

The ideal would be I guess a GU4 type bulb and holder, or something like it. I can reuse the reflector of course, but I'm not sure if there's anything it would attach to out there. I could make a holder out of Delrin but I'm not sure Delrin and a 150W halogen bulb are a great mix.

Thread: motor insurance rant
15/06/2022 22:47:43

> if insurance companies didn't play this silly game with renewals they could keep their own cost's down

Insurance is an odd business where the normal rules of competition don't quite apply in the same way. Renewals are a good illustration of this dynamic.

Year 1: insurers A, B, and C all charge about the same and all have about a third of the market.

Year 2: insurer A increases renewal prices. Some customers stay and some leave. Because A's old customers are paying more, new customers can be charged less.

Year 3: B and C have a problem. If they stick to their old method, they are now more expensive than A for new customers. In addition, their old customers are eyeing up A and thinking about switching.

Year 4: all three insurers are now charging low prices to new customers and high prices to old customers. No one company can stop doing this alone or they will get no new business.

In fact this dynamic applies to almost every feature of an insurance policy. I am sure a few readers here remember when insurers started introducing smoking and non-smoking rates and how quickly the whole industry adopted them: they had to, otherwise they were too expensive for non-smokers, and therefore ended up with only smokers - who of course claim more.

The only solution to these dynamics is mutual agreement, which isn't permitted under competition law, or government or regulatory diktat, as with the abolition of gendered pricing or last year's imposition of renewal pricing rules.

Thread: Can't access MEW archive any more
15/06/2022 22:35:07

Hmm. If you've received a DD change notice to your email, you've got your new customer ID number - first few lines of the email. I can use that to successfully login to the account page on, but that same number doesn't allow login to the new archive page for whatever reason.

Thread: Query - Stub Mandrel's article on Workshop Power - MEW No.317
15/06/2022 22:26:00

Re-reading the paragraph in question, there are a few alternatives.

For boosting signal, you can get simple "repeater" devices that simply pick up received wifi signals and rebroadcast them, increasing the coverage range of the original WiFi router. There are more and less sophisticated versions of these and the more expensive ones do work better.

A second alternative is a second router, connected to the first one, either by WiFi, dedicated cable, or via your domestic power lines using special adapter plugs. This is the best option, and for something like a shed the power line option can be very good.

For a pure old-fashioned phone line, distance shouldn't be an issue unless you are running literal miles of cable.

Thread: Cutting tools
09/06/2022 13:38:35

Which set did you buy?

Generally speaking the principle is that most cutting tools cut at only one point (hence the name "single point cutting tool". Most of the different types of tool are simply to be able to get that point where it is needed. For example, left hand and right hand tools will let you cut up to a shoulder on the left or the right (though sources differ as to which is which!). Understanding this will also help you understand how to orient it in the toolholder.

An often recommended book is Sparey's The Amateur's Lathe, and although it is old school it is very clear and concise. If you prefer videos, I'd recommend the Blondihacks series on Youtube of basic lathe skills (though be aware it's easy to watch a video and nod along without taking much in...)

Thread: A mandrel for long narrow tubes
05/06/2022 11:03:14

Yes, there are definitely better choices of cutting tool, though this did better than I expected. I have a bit of a daft idea to try grinding a bit of HSS to work like a skew chisel that a woodturner would use, so the cutting edge is at 45 degrees and the front edge rides on the part.

04/06/2022 22:45:23

Had some time today after putting together the Comically Oversized Vice (I'll update another thread with the gory details) so went ahead and had a go at putting this together.

Playing around with the 8mm shaft, I'd originally imagined I could hold it in the three jaw but it was pretty obvious the runout made it a non-starter...if only I had a collet holder of some kind - wait!


In the end I did the whole thing in the collet holder and it worked so well I am sorely tempted to consider making a backplated collet chuck to hold longer stock. Here's the finished parts:


The black piece of Delrin is the tube I want to machine down, already with the 12mm hole down it. The shaft is 8mm and the tubes, drilled out in the collet holder, are a nice sliding fit. An O-ring protects the face of the collet and the nut at the other end compresses the six pieces:


The holding force on the part is excellent; once installed, I couldn't begin to move the part, and the assembly was more than stiff enough; there's no measurable bulge due to deflection in the final part. Here it is being machined:


I mostly took 1mm depth of cut with fastest carriage feed; I'm not sure exactly what it is as my geartrain is set for screwcutting, not feeding, but it was Quite Fast. My last couple of cuts were slower with a 0.5mm DOC which produced a good finish (for Delrin!)

This whole setup worked so well I might consider replicating it for other workholding jobs - inevitably, woodwind instrument making involves holding an awful lot of things with holes up the middle...

Thanks to all for your helpful suggestions; getting to this point would have taken a lot longer without your advice!

Thread: Headstock problem
03/06/2022 22:12:02

Chris, I can empathise! When it's all going wrong it's immensely frustrating and you really feel your lack of experience and knowledge.

But when you finally get it sorted, all that frustration will be forgotten in an instant, no matter how long it took.

A piece of advice I often give my students is that you don't have to solve a problem in a day. Work on it, think about it, research it, then sleep on it. Brains are strange things and sometimes need time to make new connections.

Thread: Questions on an MLA inspired toolpost
31/05/2022 22:12:07

Posted by Nigel Graham 2 on 30/05/2022 23:30:08:

> A slot-drill rather than end-mill, surely, to cut those big slots?

That's what I thought but the more I read the more confused I get, and I've read a couple of comments that rippa-style end mills are preferred or at least equal for hogging out stock like this. I'd definitely like to take advice on this as I will have a few of these to do and given that it'll be done in a vertical slide setup I want to make it as pain free as possible! I don't want to waste money but for something like this I don't mind buying the right tools for the job.

> You might in the end find a separate spanner more of a faff than a handle, so if 'twere I designing this, I'd do so to keep my options open - allowing simply swapping nut with handle or vice-versa. It may prove possible to adjust the handle's operating arc by washers to keep it in the optimum position for your use.

Yes, I'm retaining the original toolpost stud and I'll be using the original handle in the first instance. It's a bit of a pest as is as the handle can foul the tool-holding studs, so we'll see how it goes.

Thread: What is "Mathematics"
30/05/2022 23:08:47

Yes, prior to Argand imaginary numbers were just considered to be irreducible sums: 1+2i was just two components and you couldn't really say anything more about them. Argand's contribution was recognising that multiplication by i had a very natural geometric interpretation, and it's this that makes the use of complex numbers as a sort of transform for working with oscillations so powerful.

Thread: Questions on an MLA inspired toolpost
30/05/2022 22:36:42

screenshot from 2022-05-30 21-41-54.jpg

Not much change, really just an update to the wedge shape and I've added a 5mm hole at the opposite edge to the dovetail to act as a sort of hinge.

screenshot from 2022-05-30 21-42-48.jpg

I'm not sure if I'll want to use the current toolpost handle; I suspect it might be a faff. I might make a long hex nut and washer and keep a dedicated spanner on hand for it.

I'm still not convinced of the necessity for radial registration, but it occurs to me the 5mm through hole would take a 5mm drop-in shaft nicely, so if I change my mind it's just a case of transfer punching a hole.

One question I will need to answer quite soon is: what do I need in the way of milling cutters? I already have a dovetail cutter, as it was on sale, and a cheap 12mm end mill from the auction site. With a lot of metal to remove in the tool holders, I suspect I want a decent sized roughing end mill, within the capacity of my lathe.

Thread: More beginner questions
30/05/2022 20:08:41

> the tools I got with the machine, are they ok or should I buy some new one, also what’s the round one for

The material they are made out of will be just fine, but they will need to be sharpened - even if they happen to be sharp now, they won't stay that way for long. Sharpening can be a bit of an intimidating topic to start off with, but watch a few videos and read a few books and then get your hands dirty and it will make sense. A basic bench grinder is all you need - there are usually loads on Gumtree and Facebook Marketplace for not very much.

Round tools are generally used when you want to be able to fine tune the orientation of the cutting point, such as in a boring bar. Not quite sure what this particular one is ground to do, but people do all sorts of things with HSS cutters.

> is it the tool I used or me or maybe the metal

It could be a bit of all three. The biggest problem is that the tool does indeed need to be at centre height - one easy way to text this is by almost touching the tooltip and a centre in the tailstock. People will say to be a tiny bit over or under for different applications but the basic principle is it has to be on the centre, or your tool is at the wrong angle to the material it's cutting. Your tool there is quite low so the material itself is trying to "climb" over the tool - that's why the finish is worst at the tip, where it's most slender.

The tool could be not-sharp, and your tool-holding might not be rigid - everything has to be tight all the way from the tool-tip down into the carriage, through the bed and back into the headstock. And the metal you are cutting might not be ideal, though it looks like you've chewed it up pretty well! In general though having material of a known standard and thus properties means you have one less thing to second-guess.

Thread: What is "Mathematics"
29/05/2022 18:49:38
Posted by Clive Steer on 29/05/2022 15:37:09:

I'm not sure I understand Andrew's comment that mathematics may not be correct or consistent. As far as I understand, and I'm not a mathematician, mathematics is a rules based system and we have defined the rules so how can it be inconsistent. Similarly computer instructions are a set of rules if the program you've written using them doesn't do what you need the fault is with the coder not the code.

The point is that when we do mathematics, we set some starting rules, called axioms, and then we deduce what those axioms imply. If we deduce something that makes no sense, we go back to our axioms and tweak them. The "rules" are implied entirely by the axioms and the use we put them to.

This has happened several times - Newton's laws have already been mentioned, but in fact Newton's entire edifice of calculus was in the early 19th century found to be built on weak foundations, and the modern concept of real analysis was born, one of the first "real" bits of mathematics any undergraduate does ('real' in the sense of 'real' numbers). This work gave rise to questions about what mathematicians could compute and whether the subject was open ended or whether it could be completely catalogued, work which turned out to be closely related to mechanical computation, and we all know where that ended up.

What Godel found was that once you have set up some axioms and deduced their consequences, there are true things that you can't prove with those axioms, and that you can't prove that the axioms don't result in something clearly wrong. In other words, can you start out with the axioms, do correct operations, and end up with a result like 1=0? Godel proved that you can't prove it. Similarly, any open conjecture, like the 3n+1 problem, might just turn out to be an example of a property of numbers that we can't prove using our normal mathematics.

If this feels unsettling, it should.

Thread: An ER32 MT5 collet holder
28/05/2022 22:27:53


A finished collet holder, along with drawbar and washer. As can be seen from the (posed) action shot below, it's ended up a good bit longer than necessary:


I cannot lie, the temptation to chop the nose off and make it a bit shorter is tempting. However, it works, and while it looks a bit daft I can't see it causing a practical problem, and I'm not short of room on the bed of the lathe. Plus, if I use it to hold stock I have lots of depth, and there's actually lots of meat to drill it even deeper if I wanted to.

A couple of things do bother me: the finish is terrible. I'm using cheap carbide inserts and these are probably part of the problem, but I think the biggest problem was the the dog and driving pin contained enough mass to cause a good bit of vibration while turning the morse taper. I tried several iterations of speed and feed and depth of cut and was never really happy with anything by the time I hit dimension.

The other thing is that the threads are really poor in appearance. I was having a senior moment and started cutting the threads by plunging into the work with the cross-slide, rather than setting the compound at an angle and using that to advance the cut. Whether that was the cause or something else, I am not sure but the threads look awful - lots of tearing/scaliness. Would a thread file clean it up a bit? There is a bit of wiggle room, as I stopped as soon as the nut threaded on, so a little more could come off safely.

One issue I had was that it turns out my toolpost doesn't have enough vertical height to put boring bars on centre. I ended up bolting the 16mm dia boring bar to a piece of 8x20mm flat stock and clamping that in the toolpost with lots of shim; I think well-boiled spaghetti might have been more rigid. It took a bit of fiddling to learn to take an effective cut with it - too small, chatter, too big, it shifted under the load.

All in all, I learnt a lot from this that will be useful in future, so I'm glad I went ahead with it. I'm finding myself getting a lot more comfortable working with the lathe and knowing what to do to get good results.

The next project is to setup my comically oversized milling vice ('hmm, 4" doesn't sound like much, that's do fine', I said to myself) to the vertical slide, and once I have that secure and square I can bash on with the QCTP build, and then maybe I can make things :D

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