Member postings for Kiwi Bloke

Let's think a little further outside the box...

It's often easier to locate things accurately than to machine them accurately, or to make sure features are accurately positioned when machining (unless you have a jig-borer, etc. in your shed). Accurate location may involve just simple metrology, and/or the production of simple but accurate jigs and little force needs to be applied. (Also, nothing's whirling around, and you're not removing material you can't put back...)

You could bore out whatever is to receive the bearings, roughly and oversize, then effectively cast the bearings' location with one of the filled epoxies (Moglice?). If the bore and bearings are thought of as a negative, a positive can be turned, and set in the desired position, within the rough bearing housings, and the gaps filled with epoxy mix. The resulting housings will be as accurate as you made your 'positive' pattern and positioned it. (Just be careful you design it so it can be removed...).

R Smith 1 - I'm envious of your free-bass CBA. I'd like to learn B-system CBA, but the chance of getting such an 'exotic' beast here in NZ is tiny.

At a trade show, some years ago, I was given a small sample piece of stainless shim with intricate outlines and very narrow slots CNC laser-cut in it. Beautifully clean edges. I'll post a photo, if I can find it. I guess if that service is available in NZ, it will be available in more advanced countries...

Re my previous comments about milling machines. I don't wish to discourage you, if the desire is strong, but do be aware of the necessary expense and the need to learn quite a bit. I can't believe that many luthiers or accordion-makers have milling machines. After all that, when the machine is sitting idle, because it's easier and quicker to grab a file, just remind yourself that it really was money and effort well spent...

Edited By Kiwi Bloke on 27/06/2023 02:21:45

Julius - I may be at cross-purposes, and my U3 is not to hand, at present, so what follows may be less than helpful...

The leadscrew should indeed be well supported at its right-hand end, but it is minimally loaded an any radial direction, so a 'feeble'-looking bearing, of small diameter, is OK. What is critical, however, is that the leadscrew must be properly axially constrained, thus thrust bearings are required to react screw thrust in both directions. The thrust bearing arrangement needs to be adjustable. Emco's threaded handwheel and nut design isn't the best - in fact their feedscrew axial constraint and thrust bearings are poor on many of their smaller machines - but, with patience and bad language, it can be just about be made to work - just not very nicely. You've already discovered that it may be necessary to fettle the face of the handwheel.

What happens at the leadscrew's left-hand end doesn't really matter, as far as axial constraint is concerned, so an apparent gap is OK.

If this isn't clear, the point is that axial constraint of the leadscrew should be afforded by its right-hand bearing (only). Plenty of opportunity to improve things here...

You could probably salvage the right-hand end's end (?) by axially drilling the leadscrew and fitting an extension into the hole (threaded + Loctite), and then turning it back to desired dimensions to fit bush, handwheel, etc..

Edited By Kiwi Bloke on 27/06/2023 02:06:03

... and it's easier to make the piston to fit the bore, rather than t'other way round.

Indeed. Thanks. We're doomed...

'Greenerc.com'? Ironic greenwashing I'd say.

Microfibre cloths are an environmental problem - they shed microfibres (no surprise, really), which are plastic, of some sort. To answer your question, they certainly aren't all the same. Apart from any other diffeences, their propensity to shed fibres varies. My wife was conned into buying a very expensive glass-cleaning cloth, and it works excellently, leaving few, if any, visible fibres. Other cheapo cloths leave fibres in profusion, and they're damned difficult to get enough off the windscreen so it isn't worse than before the 'cleaning' started.

What looks like a slotting head has 'Victoria' cast into it. A now-defunct UK makwer of quality industrial equipment. The articulating vertical head on the mill is a desirable feature. No quill head shown, however. Info about Victoria on www.lathes.co.uk. Sounds like Aladdins cave! A good buy! Who cares about the house?

Edited By Kiwi Bloke on 25/06/2023 07:13:43

Jason beat me. Agreed, 4BA likely. BA threads were used widely in UK, especially in electrical apparatus, millions of holes tapped in brass to receive them.

Yes, I've had a Monodex since the early 70s, and have enjoyed its use. Great tool, agree about the adjustment. The problems are the serrated 'blade' that leaves a serrated edge on the stock, and the need to cut very narrow parts. Some of these accordion reeds may be only 3mm or so wide, and need to be to accurate dimensions, with tight tolerances (a few thou on width - sorry about mixed units). Their sides are also stepped, being wider where the fixing rivet sits. So I think that, at least for DIY, they will need to be worked down to size. It's not an attractive prospect! If it's not a diatonic accordion, there are two reeds per note, and a full-size treble keyboard has 41 keys. There are also usually multiple banks of reeds. I think the OP is brave or misguided...

Edited By Kiwi Bloke on 24/06/2023 11:40:40

The OP's application is for work finer than a Monodex (or similar) can produce. Actually, quite a challenging task.

Do you really need to go down what can turn out to be a very deep and expensive rabbit hole? A milling machine needs to be equipped, even for simple jobs. You'll need work-holding equipment (vice, clamps, etc.), work setting equipment (parallels, V-blocks, edge finder, etc.), drill bits and milling cutters (so many choices...), chucks, metrology equipment, and so on and so on. And then you'll need the background information about cutting speeds and feeds, and so on. You'll also need to accept the limitations - or take steps to overcome them - of a little machine that may not be the best engineered...

Thin sections of soft metals can be easily worked by hand, and accuracy can be aided by the use of improvised jigs and fixtures. Files are wonderful things, but you've got to be prepared to buy the correct ones for your application(s) and preferred way of working. Buy good makes (eg Grobet, Vallorbe), and you'll wince at the price, but they're well worth it.

I would think that most accordion reeds start as blanks, punched from spring steel sheet or strip. This would allow the wider part around the rivet hole to be formed at the same time as the thinner vibrating part., and all pretty much free from distortion. The desirable 'hand-made' reeds start as a strip, the same width as the part around the rivet hole. Their characteristic blue edge beside the rivet hole is the blue edge of the parent strip stock. In these reeds, I don't think the tongues could be punched to width, so perhaps the tongues are, in all cases, formed entirely by machining. The apertures in the reed plates are, I believe, broached. And then an old gaffer in a ramshackle Italian cottage-factory got to work with files (or a filing machine if they were flush) and abrasive belt sanders. Or you could buy them... Stick 'Carini de.na.' into your search engine: I can't remember whether bare tongues are available from there, but everything else is.

Marks & Spencer?

If you're using common-or-garden O rings as belts (they're so cheap!), you'll find that they're soft enough to work pretty well in V grooves - possibly better than in arcuate-section grooves. The other suggestions of poly-vee or toothed belts are certainl better, but more $$ & more work...

Just a thought: O rings won't transmit as much torque as you might sometimes like. I've never seen it suggested, in this application, but running more than one belt, on multi-groove pulleys would multiply the torque transmission, in proportion to the number of belts. It's a standard technique with V-belts, but these aren't particularly stretchy, so they need to be of matched dimensions, so that they share duty pretty evenly.

Edited By Kiwi Bloke on 23/06/2023 08:05:24

Another thought. Beware, abrasive cutting may heat the reed enough to change its temper.

Apologies for the yellow winking thingie in previous post. Too late to remove it now. Grrr!

Just for clarification, before someone tells me that raising tools above centre height will prevent them cutting because they'll rub. What I've said assumes that tool angles are adjusted to account for the centre height variation. Think of it as rotating the tool and its point of contact clockwise about the lathe's axis, viewed from the tailstock. Tool movements remain conventional, of course.

R Smith 1 - There are, or used to be, people in Italy who spent their working lives making reeds. It's a specialised craft, and no doubt some of the techniques were kept pretty secret. However, videos are around that show a little of the process. You've probably already discovered that, apart from the profile of the reed having to be accurate enough to fit the aperture in the reed plate with minimal clearance, the reeds can vary in thickness along their length. And then, for bass reeds, have lumps of brass soldered to their tips. Complicated things!

I'd imagine that the blanks were guillotined and then fettled by belt sander and file - a finniky and slow job...

Good luck. I also have an accordion I'm (occasionally and very slowly) rebuilding.

Ady1 - yes he is (and I don't know him, officer). A national treasure!

Unfortunately, I can't recommend a carb cleaner, although I've used a few. I have a 4-stroke petrol generator - needed because the mains supply is vulnerable here in rural NZ. In the past, every time it was needed, or even tested, the wretched thing would not start, or wouldn't run cleanly until I had taken off the carb and removed and cleaned the jets. The trouble seemed to be salt formation on/in the brass (?) jets, which was not touched by carb cleaners. There was also gum and 'varnish' in the float chamber, which any tried carb cleaner dissolved.

This jet corrosion is the result of water in the fuel. It's a much greater problem now that there is alcohol in fuel. Thankfully, there is one (but only one) fuel mix, available in NZ, (NPD 100+), that is alcohol-free. I now use this in all my small engines that are intermittently used, and have had no similar problems. That's tempting fate, isn't it?

Does anyone know whether - and how - fuel 'stabilizers' work?

Edited By Kiwi Bloke on 21/06/2023 23:10:55

Maurits, take heart, you're not alone. Parting, or even 'normal' turning with a tool with a large nose radius causes folk a lot of problems on small lathes. Essentially, it boils down to the desired relationship of the tool's tip and the work piece being disrupted, either by unwanted movement, or unintended forces.

Myfords are relatively flexible, especially if using the topslide, and, as has been said, free movement of workpiece may be caused by worn mandrel bearings, or free movement of the tool may be the result of slop in the feedscrew nut or the feedscrew's thrust bearing, which is awkward to adjust nicely.

In another thread, I asked why some early lathe-use books (and not so early: it's included in South Bend's 'How to Run a Lathe' advocated setting the tool above centre height. As machines have improved, this advice has disappeared, but it shouldn't be forgotten. I'll now answer my question...

A properly set up cutting tool experiences three forces: 1. force of feeding, towards tailstock; 2. away from the workpiece, pushing the tool out of cut; 3. tangentally downwards. This last force is by far the largest. It will try to bend the tool's support, and this will result in the tool cutting deeper - an unstable condition that will end in tears.

It is important for there to be a force pushing the tool away from the work, because this takes up the feedscrew's two backlashes. The direction of force 3 (and therefore its horizontal radial component) is the major determinant of whether this occurs or not. If there is any inwards component of this force, the tool will get 'sucked in'. The idea of setting the tool on centre height (apart from avoiding facing pips) is to ensure this force is vertically downwards. If the tool is below centre height, the tangential force swings round, so there is an inwards component, trying to pull the tool inwards, deeper into cut. Of course, flexibility in the machine allows the tool tip to be deflected downwards, so it's all rather difficult to achieve theoretically correct conditions, all the time (ever?). Avoiding this is the justification of rear tool posts, with inverted tools: they deflect upweards and swing out of cut - a stable condition.

The idea of setting the tool tip above centre height (tangent point about 5 degrees rotated clockwise, as viewed from tailstock), is to direct the tangential force 3 so that there is an assured outwards component, hopefully keeping the tool pushed outwards. Also, of course, it allows for downwards deflection of the tool.

Beware of tools being below centre height. This is an unstable condition. At first sight, it looks attractive: a 'scraping cut' has to be safer than a 'proper' cut, doesn't it? Well, no! Emphatically no!

Hooray! Michael's got it! Far more succinct than my rambling...

Apologies to Monsieur Belleville for mis-spelling his name (the shame...).