Member postings for Calum Galleitch

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

The trick is that 'mathematics' is itself an abbreviation: there is no such thing as a mathematic, but there are mathematical arts, which was long ago abbreviated to 'mathematics'. In America, they had lost the adjectival sense of the word, so when 'mathematics' was felt to be a bit of a mouthful, it became 'math'. In the UK, 'maths'.

One of the big issues with maths is that we have practically no trained mathematicians in our schools. A century ago most Oxbridge mathematicians found jobs as school teachers and trained the next generation. Nowadays anyone with any mathematical competence can earn far higher salaries doing almost anything other than teaching, and the result is that most maths in British schools is taught by English and PE teachers (who do the very best they can, in fairness). It's hardly surprising people struggle with maths when their teachers barely understand the subject.

Spot on! Yes, decorative (and protective) mounts, which are usually nowadays plastic or resin, sometimes wood, formerly ivory, catalin (a relative of bakelite), casein (milk!) or celluloid.

Really, any tool steel would probably be fine without heat treatment - I use untreated silver steel for long hole boring in wood and delrin and have no trouble with it. But I'd like to ultimately get to the point where I'm able to bang stuff out quite quickly, and wood can be surprisingly hard on tools.

I posted this as an idle query in another thread, but since it threatened to derail the thread I thought I'd better split it out. My original query:

> While we're on the subject, can I ask about filing HSS? I'm interested in making form tools - I know I can heat treat O1 or the like but I'd like to avoid the extra faff. I imagine diamond needle files are the way to go here but I'd like to get one decent set that will last.

The reason I'm thinking diamond files is the shapes I need to create are quite small and while a grinder could do some of the work, I'm thinking of things like this:

The blanks were drawn at 5mm (vertical) across, and most would be in this range. The notch in the bottom one is about 1mm wide and deep.

While we're on the subject, can I ask about filing HSS? I'm interested in making form tools - I know I can heat treat O1 or the like but I'd like to avoid the extra faff. I imagine diamond needle files are the way to go here but I'd like to get one decent set that will last.

Also worth asking: what kind of wood? There are certain species that have mineral inclusions that make them more akin to biological grinding wheels than free-cutting lignin.

Finally got round to giving this a little more thought! Thanks all for the suggestions and input. I want to make something I can easily use repeatedly, and I was also trying to work out how to easily machine the whole length in one operation, so putting together your comments I came up with this:

Lots of o-rings, not so much to grip the part but so that the piece doesn't flex under cutting load - I did another long piece the other day at 16mm external diameter with a ~3mm hole down the middle and it has a huge bow in the centre of the piece where the cut was unsupported.

The internal shaft will be threaded at both ends so a nut can bear on the two end pieces - I've drawn these as a single part but I would think in reality a washer would be fine.

Good heavens, Howard, that brings back memories. Somewhere I have a very, very old LP with Pete Seeger's rendition of it.

Well, finally a quick progress report - no pictures so far, I'm afraid, I forgot to bring the phone to the workshop two days running. I've been following the process I outlined in my original post and have the taper cut and the drawbar thread drilled and tapped. I've also made the drawbar washer and chopped off a piece of studding to length.

It's been a very educational experience so far. One of the preliminary projects I had to do before this one was make a driving pin for a lathe dog; I decided to make a pin with a camlock stud on one end. I have two quick tips here: one, you have to put a shoulder where the ISO drawings show a setting line, and secondly, interestingly the length of a D1-5 stud to the setting line is the same as the overall length of a D1-4 stud, so I managed to read the wrong set of measurements and now possess the world's only double-ended camlock driving pin. The good news was that the circular cutout on the stud is about the same radius as my semi-circular bastard file.

On the collet holder itself, I used two indicators to establish the offset angle, but it hadn't occurred to me that it only works if your stock is parallel to start with, and it wasn't until several iterations of altering the tailstock had occurred that I worked this out - so back to getting it on centre, an adventure in itself. It took quite some time to dial in the angle I wanted, and one thing I should have worked out before I started was the necessary tolerance.

Using the change in the indicator readings, I was working out the tangent of the angle defined by the tailstock offset, aiming for tan(1.5072), which is about 0.026312. I found trying to get that fourth decimal place was a frustrating exercise; it's at the point where merely taking the slack off one set screw and retightening the other moved it further than you want. Having got to about 0.0264, I decided that I wasn't going to get closer and went ahead and cut it.

The actual cutting was straightforward and having cut the stock over length in case of error, when I got the small end to dimension I tried a test fit and...a solid fit. I had to knock it out again. Being a simple creature, I stopped there, on the premise you should quit while you're ahead.

The next day involved the making of a test bar to get the tailstock back on centre, which I hadn't previously done. It turned into a faff, as it was too small for the driving dog, so I made a little cutout piece on the bandsaw to clamp it properly, during which the bandsaw threw the blade off, then I couldn't get the cover back on...some hours later though I had two flanges, one reading 24.71mm and one reading 24.72mm which as we all know is the same thing.

The drawbar hole has now been drilled and tapped, just held in the three jaw, and the part is now sitting in the spindle held by the drawbar. I've turned the straight section to a hair under 40mm ready for external threading, and drilled the first pilot hole for the internal hole.

The part is quite a bit longer than it needs to be at the moment; I think I'm quite happy leaving it as is as it gives me scope to screw up and will work fine if I get it right first time.

I'd like to make a Delrin tube, of 2mm wall thickness, 12mm I.D., and around 210mm long.

I can drill out a thicker piece of Delrin rod fairly successfully with a pilot hole made with a single-point silver steel drill and following up with a standard, then long series 12mm drill.

To then turn the O.D. to final diameter, I want to mount the part on a mandrel both to stiffen the part while turning - it's wobbly stuff at this size) and to be able to finish the O.D. in one pass.

There doesn't seem to be much out there about mandrel designs for this specific application, so I have come up with a rough concept:

**LINK**

Four widgets slide on a shaft; the edges are chamfered to create a V-groove in which an O-ring sits. They are tightened by a nut on the end of the shaft which expands the O-ring and holds the workpiece.

So far, so theory! I'm finding it difficult to imagine the magnitude of forces at play here: would this thing actually grip against a cutting force? Obviously Delrin is soft stuff but I'd be taking a good bit off per pass, ideally.

Second, perhaps daft question: From my sketch, it seems to me an o-ring of 2mm thickness and 8mm internal diameter would be about right, but how would I go about being more exact about this? Presumably I can play around with the size of the chamfers and O-ring to achieve an optimum, but at this point I'm not necessarily sure what optimum even looks like!

I'd guess it was listed as such to act as a spacer.

Tristan, it's worth looking at your chart and thinking carefully about what's physically going on, because there's often different ways of doing something when it comes to the change gears. My lathe for example lists a specific setup for most metric pitches, one of the gears for which I don't have (my lathe also came from a school and arrived without the other changewheels...some kind of vortex, perhaps). However, close inspection reveals the "missing" gear is just an idler, so can be replaced with any gear that can be made to fit.

It's also worth figuring out what the calculation is to derive the thread pitch, as once you have that you can then work backwards and invent your own change wheel combinations.

A couple of months ago I realised that condensation would do for everything in my workshop if I didn't address it. I now have a very cheap fan heater attached to a little plug-in thermostat. It kicks in when the temperature drops to 6C and off again at 7C. It obviously consumes some power but watching the meter for the last couple of months I can't discern any impact, and we don't use electric for heat or hot water at all here.

Obviously 7C is not a lot but it made the workshop tolerable for me. I did have an old gas fire in there which gets the place toasty in short order, but it gives off so much water it's like a sauna after an hour or two. Since putting the fan heater in it hasn't been on once.

Here are two M8 threads I made recently (on the left; originals on the right). All I can say is that die thread imparts a considerable twisting moment - think of how hard you have to turn a die, and consider that force is being applied at a radius of a few millimetres. Fortunately in the case of these t-nuts I don't have to look at them, but I'd be interested to hear any tips on getting them straighter as well!

I think the point is that if you're not confident, then there is a fair chance that you will not in fact be methodical and end up holding two ends of a live wire. I did it myself some years ago replacing a bathroom downlight; having got the thing to bits I couldn't see something clearly so muscle memory took over and a hand reached around the door and flipped the bathroom lightswitch...zap! Fortunately I was only holding on with one hand so nothing more serious than a spicy thumb, but it was a useful lesson, one which could have been learnt an easier way.

Perhaps a substance sold as "funky foam": a closed cell sponge sold in varying thickness of sheets in various sizes, many with a peel-off-and-stick backing.

Sounds complex to me.

Well, I haven't measured them, but they came without any specification, and at least one of them has a slit where the slitting operator got about halfway through, was interrupted for some reason, and started again leaving a very obvious ledge of saw kerf. Once the ER collet for the big lathe is done I will try indicating a few with some circular ground stock and see how bad they really are!

Assuming you are not peeling off tenths with your turning tools, you're applying as much force with a cutting tool as you are with a die, or thereabouts.

The two obvious things to me, besides checking the chuck is in good order, are (a) is it definitely mild steel and (b) is it definitely a 3/8" die and it hasn't been cranked up tight by the Incredible Hulk?

It's a real pest, and one of the reasons I have over the years stuck with a hi-fi, vinyl and CD collection. I do have a small MP3 player but I consider it disposable. I bought one of the very first hard-drive music players, preceding the iPod, and it was wonderful, and longer lasting than the typical iPod, but the software to rip and download files to it have not been available for decades. I have a £20 digital radio in the workshop but in general I try to avoid clever consumer electronics. I also avoid laptops and use desktops with standard components for the same reason.

The fundamental problem is that hardware once sold brings in no cash, but programmers to update firmware and maintain websites and so on cost a fortune, so anything that relies primarily on up to date software is at risk. I think this is gradually becoming less of a problem - my phone is five years old and still in good order, and doesn't appear hopelessly clunky and out of date as a five year old smartphone once did. The raw power of modern electronics is starting to struggle to find a use for most of us.

None of this fixes your Echo Dot, though! The answer has to be regulatory, I think; you could complain to Amazon, and if you were very pushy/lucky [delete as appropriate] you might get a replacement or a refund, but honestly I think the person to complain to, daft as it sounds, is your MP. They are the ones who can actually create a repairable ecosystem of devices, or mandate that hardware be documented for open source programmers to use.

You can just see what looks like a cross-slide on the floor in one of the shots, so there's a chance there's more there than pictured, but even so, a project is right!