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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: ER16 Collets from Ebay
15/04/2022 23:37:26

For what it's worth, I bought a set of ER32 collets plus MT2 holder off eBay in 2020 for £35 - it was a bit of an odd set, not a complete range of sizes with a few missing. They aren't great quality but for their purpose - workholding in the wood lathe - they are ideal. For the price I've no complaints.

Thread: Before calculators
15/04/2022 13:18:52

For the benefit of anyone as confused as I was!

screenshot from 2022-04-15 13-16-09.jpg

Thread: condensation
14/04/2022 13:45:48

I had damp problems in my little workshop (an old stone farm building) and I seem to have mitigated them pretty effectively with an electric fan heater attached to a plug-in thermostat. It is set to run when the temperature drops to 6 degrees and stop running when it rises to 7. The fan heater itself is adjusted as low as it can go and I think runs at a few hundred watts when it is on, which as far as I can tell isn't much, especially now the temperatures here have risen a bit. The workshop feels dry to the touch now, bits of paper left in it don't feel damp and greasy.

Thread: Acme internal threading
14/04/2022 13:13:40

There are inserts available for Acme threads, and if a suitable holder can be found at a reasonable price I think I'd be tempted to go this route. I've seen a few videos of people using Acme taps and in general, I like to see the machine doing the work, not me!

Thread: Making gears in the lathe
11/04/2022 23:47:08

Thank you all. Yes, I have Ivan Law's excellent little book, and I had forgotten it went into a fair amount of detail on setup; when I read it, I was more interested in the theory side as I knew nothing about it. I see from a quick scan that my notion of mounting it on the vertical slide facing backwards isn't completely ridiculous.

The change gears are definitely Mod 2.5 - the measurements are correct, the manual says they are, and the tooth profiles match the module 2.5 cutters I bought!

On making threads, no, I don't intend to produce vast numbers, but the ones I can do are fairly constrained and I do want to be able to do some very specific ones - for example, at some point I want to make an ER collet holder to fit in the MT5 spindle, as commercial items are £££-y, and I can't pick my own thread for that! But cutting just a 33 tooth gear would open up a lot of useful sizes.

John, thanks very much for that photograph - it makes me wonder if my cover plate is 100% correct - I've still to find time to sit down and work through the rest of the calculations, but it does seem a bit strange that it calls for a 20/40 pair there and nowhere else. Also the labelling of the ABCDE gears is different from my machine which I think matches the manual.

11/04/2022 14:33:52

My lathe arrived without a full set of changewheels, so one of the projects I'd like to do is to replace the missing items. According to John P's manual for the Warco equivalent, the gears should be:

26 27 28 29 30 33 34 35 36 38 41 43 45 (ones I have in bold)

They are mod 2.5, p/a 20 degrees, 6mm thick, and rotate on a splined hub.

However, the front panel of the lathe:

screenshot from 2022-04-10 15-58-25.jpg

also has 20 and 40 tooth gears listed (and it occurs to me I should check the imperial and DP charts as well!)

Either the Warco lathe has a slightly different internal gear train or there are more ways of achieving the same thing than what is listed - quite possible with the slightly unusual setup.

So the actual list of needed gears is pending, but in the meantime I'm thinking about the making process. I've already acquired the necessary M2.5 cutters - fortunately, two cutters covers the 26-54 tooth range. I don't have the next one down, but I suppose instead of making a 20/40 pair I could make a 52 to go with the 26.

Although the lathe has steel gears, I was thinking about delrin, for a couple of reasons: cheaper, less likely to damage the cutters, less likely to damage the lathe, and easier to make. There is already a sacrificial plastic gear so I don't think there's any reason to worry about strength.

To make the splines, I was thinking of mounting the blank in the headstock and using the carriage as a shaper. Not the quickest but should be easy enough in delrin.

It's cutting the teeth (on the lathe, as I have no mill) that has me a little puzzled. I've got an HV6 rotary table with dividing plate set on the way, but I'm scratching my head a little on how to set it up. I have a fixture plate I can attach to my cross-slide, but the centre height over this is a little under 75mm. The HV6 centre height is 100mm but more to the point I don't fancy packing it up for each different blank (the largest blank, the 46 tooth, will be 120mm dia)

The other way of doing it is to mount a vertical slide (not yet acquired, alas) and have the HV6 hanging off the side of it, which I think would be safe but hardly conducive to rigidity. Everything else I can think of seems worse by comparison. Maybe having the vertical slide facing the back of the lathe rather than the headstock and mount the table vertically on it?

 

 

Edited By Calum Galleitch on 11/04/2022 14:34:16

Thread: Install & commission of a Chester Cub 630 (Warco GH750)
11/04/2022 13:50:44

Thanks John, that certainly all makes sense and I'll just have to do a little testing to make sure it matches up with what we expect!

I didn't realise until I'd posted that the next page of the manual lists the full transmission ratios for the various systems, so that will help in tracing what goes where.

Thread: Imperial v Metric Measures
11/04/2022 13:43:50

Just on centimetres, it's not I think widely understood that the system of centi-deci-etci belongs to the metric system, but the system that we use involving millimetres and so forth is the SI [Systeme International] system, which Britain adopted in the early 60s, I think. They look very similar, and for everyday purposes are interchangeable, but there is a difference. The first chapter of Tubal Cain's handbook talks about this.

The main practical consequence of the change is that certain prefixes are no longer in official use. The definitions of certain units are also derived differently, in particular the unit of force.

Thread: Install & commission of a Chester Cub 630 (Warco GH750)
10/04/2022 17:22:06

I'd like to have a go at making gears to make up the missing changewheels that I have - I think I'll do a separate thread about them as it may be of more general interest but I'm just trying to understand the gear train of my lathe:

screenshot from 2022-04-10 15-55-39.jpg

Beginning with the spindle, wheels 13,17,16,18, 19 and 20 have 45, 45, 45, 68, 17 and 45 teeth, so for one turn of the spindle A will be turned 45/68*17/45 times = 1/4 which is what John P wrote last year...so far so good!

Q. Where/how is the reverse in this diagram? Physically on the lathe it's somewhere round the wheels labelled 17-18 but unless the reverse mechanism is not drawn I don't see how it works.

In the quickchange box, 21/22/23 mesh with 29/30/31, giving ratios of 20/40, 40/20, 30/30 which corresponds with the 1/2/3 knob. Like wise the second knob, 24/25/26 mesh with 32/33/34 giving 20/40, 42/24, 36/24 (1/2, 7/4,3/2).

Finally, if the leadscrew is selected the drive is fed through wheels 36 to 28, which are 45/21.

Q. Am I right in thinking the manual states it is a 4mm pitch leadscrew? Slightly alarmingly it gives "module no. or pitch" as '4 or 1/6" '. Now 4mm is close to 1/6" but it's not that close!

Putting all this together, If I choose to cut a 4mm thread, I take A,B,C,D=36,27,28,30 teeth from the front chart and select 2,II (30/30, 36/24). One spindle revolution then gives:

1/4 * 36/27 * 28/30 * 30/30 * 36/24 * 45/21 = 1 turn of the leadscrew, so if it is a 4mm leadscrew we've got a 4mm pitch. Phew.

When the feed is selected, the 45/21 drops out and the feed rod turns.

Q. What is happening at 44/45? Clearly this is where torque is being taken off the feed. Then (assuming carriage feed engaged) 48 drives 46 which drives the wheel engaging the rack? But what are 50/51/52 doing?

Similar for the cross-feed I assume 47 engages 48, in turn driving 49.

I'll add the manual pages for the gear list to my lathe album should anyone feel inclined to try and make sense of it!

Thread: Imperial v Metric Measures
09/04/2022 14:59:48
Posted by PatJ on 09/04/2022 03:22:51:

The metric-pushers don't have to build buildings and stuff is my guess, else they would revolt.

Completely correct, we haven't built anything here in Europe since the French Revolution. Every we time we start digging a foundation we get confused and have to go on strike.

Thread: Lathe gear calculation
08/04/2022 22:24:21
Posted by Calum Galleitch on 10/07/2021 14:00:26:

John, I quite take your point about the output requiring some intelligent interpretation. There's a balancing act between making such a tool capable of handling every case correctly, and it becoming too difficult to use for anyone but an expert - who probably doesn't need such a tool to begin with!

cool

Thread: Advanced Grinding Rest
06/04/2022 23:44:15

What lovely looking work, John.

I think Harold later decided to use a couple of cheap magnetic bases in preference to screwing the rest down, as this lets you slide it into approximate position easily without having to set up all the adjustments.

Thread: Questions on an MLA inspired toolpost
03/04/2022 16:28:31
Posted by duncan webster on 03/04/2022 14:57:03:

But Calum's is different, very slow taper on much longer expander plug

Well, this iteration is :D

pkg's question about releasing made me realise (a) they are quite right, releasing a gentle taper would be a pest and (b) there would be practically no downforce to hold the toolpost against rotational forces. I also did the trigonometry and realised that the plug would sit about 30mm proud when the toolpost was in a relaxed state, so some redrafting will be in order, starting with a self releasing taper.

On radial location, I take the point about rotation under load, but my four-way toolpost has no locking either and in my experience so far the tool itself slips before the post does.

02/04/2022 20:39:42

Yes, I wondered if it would be better at the other end - I put it at the back so it wouldn't be getting in my sightline - but in theory the toolpost should be pulling the toolholder horizontal anyway. My only puzzle is to what extent theory actually applies!

There's no radial registration (nor is there in the original design, I believe). Maybe it's my inexperience, but I don't really feel the need for it. For something that required good alignment, like a parting tool, I'd indicate in anyway, and most tool alignments aren't crucial. I do have a ratchet-type pin on my top slide although offhand I'm not sure if it's in a useful position.

02/04/2022 18:24:18

As I mentioned in another thread, I have been doing some basic CAD modelling of my own version of a QCTP inspired by the MLA-23.

screenshot from 2022-04-02 17-40-51.jpg

The dovetailed toolpost as drawn is 80mm in diameter. The hole has a 1 degree taper, matched by the internal piece shown behind in grey. The diameter of the external piece at the bottom is 55mm and at the bottom of the internal piece 56mm. So if the internal piece were to bottom out the dovetail pieces would open by just over 2mm. Of course the plan is that the toolholders will constrain the amount of opening on the order of 0.1mm.

Two questions.

One. The narrowest part of the external piece opposite the dovetail is 7.5mm. Is this thin enough that the external piece will actually bend sufficiently under reasonable force from the toolpost handle? A cantilever beam of the same length would deflect several mm under 100N of force but of course the forces here are not normal to a 7.5mm cross-section. I could (and would) alter the distance or add a groove as Alan Jackson has done in his very attractive version, but I'd like to start off in the right ballpark.

Two: Rather than have the height adjuster in the centre, moving it back allows the toolholder to be a little narrower. Is there any reason this might cause an issue? I can't see that it would, but better to know now than later!

Thread: The ettiquette of sharing designs
01/04/2022 23:44:37

This is not a question about the law of copyright, which I understand reasonably well. It's more about what the norms/expectations are in the world of home machining.

Specifically, I've been drawing up a few different bits and pieces in OnShape recently (a Fusion360 equivalent), and I'd like to share some of them both for feedback and in case anyone should find them useful. Specifically, they are:

  • A float-lock vice (a light drilling vice)
  • Harold Hall's QCTP
  • My own version of the MLA-23 toolpost.

The float-lock vice I have drawn up from pictures and videos. I don't think they are made commercially and the designer has long since departed. I am fairly sure no form of legal protection exists and I would have no qualms about sharing this.

Harold Hall's QCTP is his own design, is copyrighted, and even though his design is free to download from his website I don't feel it would be right to publicly share my version without knowing his views. That said, I wouldn't feel inhibited from sharing the design with a friend or someone I was seeking advice from.

The MLA-23 inspired toolpost - although it shares the same look and operating principle as the original - is drawn from scratch, and nothing has been copied dimensionally; I have also changed the locking mechanism slightly. This is the item I feel less sure about sharing; while I don't think I would be breaching copyright, it's very clearly not my design and the designer is still selling the design commercially. On the other hand, it's a simple design and any competent machinist could knock one up from a photograph.

A lot of my thinking here is coloured by my experience of the accepted standards in my corner of the musical universe. It's normal and unquestionable for teachers to supply music to their students without seeking permissions; likewise between friends and within bands. There is however a strong culture of "buy the book" and supporting the people who put music out there. At the same time, there's a recognition that it's a bit daft to have strictures about sharing sheet music when you can simply listen to someone playing it and write that same bit of music down for yourself.

Thread: "Kiv" or Kiev?
31/03/2022 14:17:21
Posted by Tony Pratt 1 on 31/03/2022 13:39:52:

my views/opinions don't count.

Tony, it is not that your views do not count, it is just that yours are not the *only* views that count. Moreover, taking the time to understand the world as other people see it is an enjoyable activity in its own right.

Thread: Dividing head advice
27/03/2022 22:33:47

Since we're talking about dividing heads, there is an excellent series on a George H. Thomas dividing head build currently ongoing on Youtube:

https://www.youtube.com/watch?v=q57xnGpfhA8

Very well paced and explained, I thought.

Thread: Finding things
27/03/2022 15:25:38

I don't have much advice for finding the thing that is lost, but one of the best pieces of advice I've ever had is: when you do find it, put it in the place you first looked for it.

Thread: Cross-slide fixture plate considerations
27/03/2022 14:11:15

Bill, I have to confess ignorance! I didn't know such things existed, though it makes sense that they do.

I think for my purposes a caphead will seat happily on the cone left behind by a drill - I don't doubt my counterbores aren't perfectly in line with the screw in the cross-slide but it should be pretty close.

Having a quick look at available counterbore bits the counterbore size seems a bit large - to my mind a 13mm cap in a 15mm counterbore will look a bit spacious, and the pilot hole size seems to vary!

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