Here is a list of all the postings Kiwi Bloke has made in our forums. Click on a thread name to jump to the thread.
|Thread: Measurements from the past|
Mil is still used for 0.001" in that most backward ex-colony across the Atlantic. Mille, French for 10^3, but used as 10^-3, as in mm, mg, etc.
Edited By Kiwi Bloke 1 on 31/12/2018 18:53:01
|Thread: What did you do Today 2018|
I'm jealous of you lot! I'm 'between workshops', so most of my equipment is inaccessible. This morning, I sprayed (back-pack) 100 litres of glyphosate, but was stopped by the breeze getting up. Job only half-done... This afternoon, I took pity (again...) on neighbour and chainsawed up the big lumps of the poplars recently felled on his land. Two-foot diameter trunks, but easy going, for a big saw and a beer-refuelled old man: there was just rather a lot of it (I mean the timber, not the beer). One day is much like another, really...
Edited By Kiwi Bloke 1 on 30/12/2018 09:13:33
|Thread: Ball bearing spindles|
Several small lathes and milling spindles are supported by a pair of deep-groove ball bearings, often pre-loaded by 'wavy washers' or Belville spring washers. I don't know what grade bearings are generally used. If the bearings are to be replaced - but not by converting to taper roller bearings - is it worth the expense of C2 bearings?
OK, it's a 'how long is a piece of string?' question, I suppose. However, it's worth knowing the answer because C2 grade bearings seem to be made of Unobtainium in NZ. Upgrading just for the fun of it can get quite expensive...
|Thread: Emco Compact 5|
Well, I never expected there to be so much discussion about this machine. Thanks everyone for all the information and opinion. It all sounds quite encouraging.
An apparently very little-used example, complete with milling head, collet chucks, collet set, 3-jaw, 4-jaw, topslide, steadies, change wheels, dividing unit, and a few other bits and bobs recently sold here (NZ) for about NZ$2,500 (divide by 2 for pounds) - the same as a well-equipped, little-used, Cowells 90ME made. Emco gear is fought for here. Just out of interest, what would these machines go for in UK?
Quick question - it's not uncommon to see Cowells equipment sold in almost new condition: what's going on?
I've been wondering about a small lathe. The Emco Compact 5 looks attractive, and is about the right size, but is it a dressed-up toy or an accurate machine, capable of sensible work (in steel)? A certain G Meek uses one: should that be recommendation enough? Any available will be fairly old by now - how do they wear? Also, is the milling unit worth considering?
The restricted speed range, alloy headstock, saddle and tailstock, and the rudimentary fine feed for the milling unit's quill don't inspire confidence. What do users think?
|Thread: Christmas disaster|
A friend in Oxfordshire told me the following, which happened to an unpopular 'know-it-all' builder, who had moved into the area, into a large, expensive pile in the country, which he was 'improving'. I think it was just before Christmas.
Said builder had installed one of those glass-fibre septic tanks that look like a monster onion. He knew better than to follow instructions, so didn't bother with the heavy concrete collar around the top of the unit, having buried the 'onion'. The outflow field turned out to be unwisely sited, in a low part of his land. It rained. And rained. The ground got soggy. The septic tank stopped draining, and overflowed. (OK, you know why, but he didn't).
Reasoning that the best thing to do with an overflowing tank is to empty it, that is what he did. The water table being unusually high, the back-fill around the tank being not properly compacted, and lacking the mass of the concrete collar that should have been there, the now empty tank did what physics said it must, and what the displaced volume of water compelled it to, and promptly popped right out of the ground. My, how the locals larfed.
|Thread: Changes in heating equipment - and what else?|
Big changes in the last 50 years? TIG, MIG, tipped tooling - all more-or-less affordable. The demise of Myford and the popularity of oriental equipment of dubious quality. CAD/CAM/CNC. The internet, where information and mis-information compete for your attention and where fora like this enable idiots like myself to appear authoritative and reach an audience we don't deserve.
I may be missing something, but heating things with a flame is thousands-year-old tech, even if the fuel has changed. I still occasionally use a meths wick burner and a blow-pipe.
Predictions for the next 50 years?
Edited By Kiwi Bloke 1 on 26/12/2018 09:11:33
|Thread: ER Collets|
Aargh! Just noticed brain fart in 3rd line of 2nd para of my first post. Of course, I meant 'radial alignment', or making sure there's no radial displacement: i.e. making sure everything is co-axial. Confusing innit?
|Thread: If you bought this lathe what would you do?|
Good grief! It's junk! Demand a full refund, including all out-of pocket expenses incurred in undoing the deal. You have the law on your side.
Let the forum know what happened. If retailers peddle such rubbish without shame, they need to bear the consequences, including adverse publicity.
Sadly, this illustrates the problem of unreliable quality control, which appears to extend all the way from manufacturer (rather an optimistic term in this case) to retailer. With so much stuff being imported from unknown sources, often sporting 'reliable' brand names, you just can't buy on trust any more. And it's probably going to get worse, before it gets better...
|Thread: ER Collets|
Oh, forgot to say that I have a Jacobs tapping chuck, which takes Rubberflex collets. These are axially aligned entirely by the chuck body's internal taper. The closer applies only an axial force to the end of the collet and mates to the body via a 'loose' square thread. Seems like a good design... Or is it?
Thanks MG for the link. I've read it all (phew!). Some interesting content, but sadly diluted by rudeness, mud-slinging and anti-intellectual attitudes. I'm not impressed by arguments that go like: 'I was taught to do it this way, as an apprentice, and have done it this way for the last 40 years, so it must be right', or: "Just do it, don't waste time thinking about it". Kiwi Bloke's First Rule: The heat under the collar is in inverse proportion to the quality of activity above.
From the linked-to thread, it seems that lack of concentricity of the closer can / will cause the collet nose to be deflected radially. I had assumed that the collet would make contact (well, several line contacts) all along the sides of the chuck body's taper, thus it would be the chuck body that aligned the collet. However, it seems that it's only really held at the narrow end of each taper, so the closer's radial alignment is critical. Without a register, the closer relies on the centring action of a V thread, and will also be deflected by off-centre spanner forces. This probably explains the need to tighten HARD - to maximize the not-very-good centring action of the thread.
These things (most things) are more complicated than at first sight. Clearly, in practice, the things work well enough, resisting sensible radial loading, even for holding work, rather than cutters, and for use with milling cutters. However, some people experience radial run-out. I wanted to start an intellectual discussion as to possible causes and especially whether the problems were inherent in the design. Perhaps, in view of the vitriol in the linked-to thread, I was unwise.
The thread 'Arc Euro ER16 runout' got me thinking. Thought I'd start a new thread, rather than hijack that one.
I've just looked at the Schaublin collet chuck that Emco supplied for the FB2 milling machine. I'd rather taken it for granted before - it just did its job, apparently accurately. But now I'm wondering... are these things designed optimally? Clearly, axial alignment cannot be taken for granted and the availability of 'forcing clamps' (dunno what they're really called) to tweak cutter alignment suggests that concentricity may not be as reliable as one would want.
I assume that the collet is aligned by the taper in the body of the chuck. If the collet collapses symmetrically (and is made concentric), alignment should be determined by the collet chuck's accuracy. But this assumes that the collet is not able to be deflected radially as it is tightened. Is this assumption valid, in practice? There are two complications...
Firstly, the short taper on the collet's nose mates with the taper in the closer (nut). The closer is threaded to the body with a 'normal' V thread, so it is 'centred' by the thread. If there is a malalignment between the closer and the body, the closer's taper and the centring action of the thread may fight each other, resulting in a radial force on the nose of the collet. Wouldn't a 'sloppy' square thread (large radial clearance) be better? There would then be no chance of the closer exerting a radial force on the collet. (OK, we really need symmetrical spanner work, but that applies to the conventional design anyway.)
Secondly, for collets with extractor grooves, it might be that, as the closer collapses the collet, allowing the collet to settle deeper into the closer's taper, the closer's extractor (half-) ring 'bottoms out' on the collet's groove, and contact between the closer's taper and the collet nose's taper is lost. Also, the axial force would be off-centre. Wouldn't it be better for the cap to be able to exert only a reliably axial force? Why have a taper in the closer, or is it to ensure the greatest radial force is applied to the cutter at the collet's nose?
Perhaps I should just continue to take it for granted...
|Thread: Lead Bearing Solder is Banned|
Crikey! Lots of churches have lead roofs. Think of the volume of toxic water run-off when it rains. No wonder the surrounding ground is usually full of dead people...
|Thread: Machine light|
Again, not quite the direct replacement you're after. 12V (3-5W) LED downlighter replacements for 50W halogen jobs make wonderful machine lamps, but don't have the hidden 'advantages' of heating the room or providing a sun tan because they run cool and AFAIK don't emit UV. Currently a bit pricey, but I got a load for about a quid each recently.
|Thread: VW air cooled flat 4 model?|
JasonB - thanks for the pointer to the video. I hadn't found it because I searched specifically for 'Brian Perkins VW'. For some reason, it's the only thing I can remember that hasn't shown up correctly in this forum. Presumably it's because I run Firefox (on Linux) with cookies, scripts, trackers and ads controlled tightly. It's surprising how most sites still work OK with loads of scripts disabled. They must be trying to do something - but what?
Perhaps Jason B has answered, but all I see is a blank box.
A Brian Perkins (the Brian Perkins?) wrote up his BP 75 model in Strictly IC magazine, years ago. It was based on the VW flat 4, was 75cc and he flew it in a large scale model Colibri. Impressive. 'Fraid I can't provide more info. - my copies of SIC are in a box, somewhere...
You'll get a disappointing few hits from an internet search, but there's a little to whet the appetite out there...
|Thread: Spindle design|
As I suggested earlier, the spindle would benefit from being as large a diameter as the OP's application can accommodate. However, Belville washers are, IIRC, available in small diameters.
XD 351's comment about spring preload washers not controlling end-float is not strictly correct. They will not eliminate end-float, but can control it, to an extent that allows the design to be practicable. The force required to move the spindle axially can be designed to be higher than anticipated forces applied to the spindle by the cutter, etc. That this works in practice is borne out by the thousands of (fairly) satisfied Unimat users and its very widespread use in precision spindles.
The whole point of spring pre-loading in this application is because trying to set preload by screw-adjustment is difficult - you can't tell when it's correct and, in small sizes, the axial displacement required for reliably setting the correct adjustment is too small to be applied easily by a practicable-pitch thread, especially when a lock-nut disrupts the adjustment. If the adjustment of such a rigid set-up is such that the axial float is just eliminated, there will be minimal bearing preload - less than the 'correct' amount. However, setting the 'correct' amount is difficult - how do you measure it?
In much larger applications, opposed taper roller bearing-supported shafts are often set to a desired torque required to overcome the drag imposed by the preloaded bearing. Great fun, swapping shims, rebuilding, measuring torque with a spring balance pulling a string wound around a gear, taking it all apart and doing it all over again. And again. When, years ago, I rebuilt a Land Rover transmission, (LR service manuals detailed this method), I was surprised to learn that the local main dealer never opened transmissions - they just bunged in 'recon units'. The labour (and skill?) required was too much. Luckily, they carried boxes of shims for us idiots working for free, in our own time...
OK, enough of this counsel of perfection - don't be put off. You will probably get away with a screw-adjusted arrangement; make the thread as fine as you can and adjust it until there's just a little rotational drag, and there's no rattling on shaking the assembly. Spring pre-load makes life easier...
(Stupid emoji added to my previous post, apparently by 'auto-correcting' software built into this forum. Can't you just wait for self-correcting autonomous cars?)
|Thread: GEC Motor Bearings for Lathe Motor|
Andy, I can only applaud your determination to repair this thing. I would do the same. Problem is, I wish I didn't spend so much time, effort and money trying to resurrect the dead or rescue the hopeless cases (even though they turn out to be not-quite dead or not entirely hopeless). I've got to the stage where this sort of battle is no longer a pleasure, but just an annoying distraction from doing what I really want to be doing. Also, I've probably spent more money on rebuilding machines and upgrading than I would have done by appearing extravagant and buying something really good in the first place. And the time spent and the aggravation along the way is incalculable.
As you get older, you realise that time's running out. If you're lucky(?) you may be able to predict fairly confidently that time will run out before the money does. If that's the case, put a load of beer vouchers into a VFD and a 3-ph motor, and enjoy the benefits.
Not telling you what to do, just the reflections of an old one. Good luck with the project, I'm interested to see how it turns out.
|Thread: Win 10 updates (again)|
Er, regain control, dump Microsoft (and Apple) and use Linux! Enjoy Free software!
|Thread: Spindle design|
As DW above says.
Belville (cone) washers may be easier to find than wavy washers and avoid possible interference with the inner race. The washer contacts the outer race by the outer edge of its face only, and 'points' away from the bearing (towards the other bearing). Therefore install two, 'pointing' towards each other (>< the second one's OD contacts the step in the housing bore, as above. As used by Emco in the Unimat headstock - two, with angular-contact bearings in the early Unimat, 4 pairs, back-to-back*, with deep-groove bearings in the Unimat 3. You need a reasonably firm spring to resist the possibility of the spindle moving axially, should it ever be loaded towards the workpiece by, for example, a drill grabbing in brass.
* thus: >><<>><<
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