Here is a list of all the postings andrew lyner has made in our forums. Click on a thread name to jump to the thread.
|Thread: Stroboscopic effect|
Mains powered LEDs all (all the ones I've seen, anyway) flicker because the there's no crashing need for a really smooth DC supply and LEDs have no 'memory'. A thin stream of water from the kitchen tap breaks up into apparent drops. But the problem in multi-user workshops was that the background noise made it impossible to know if your machine was running or not. Working on your own is a lot safer in that respect.
If you really want good DC then make up your own lighting circuit in the workshop with a float charged 12V car battery. That will give you a good DC. Never found any problems on my boat. (Otoh, no lathe or bench drill on board)
I remember the lathe in our lab used to have a 24V transformer and a low voltage filament lamp. The flicker was much less detectable due to the greater mass of the filament.
|Thread: Exploding Grinding Wheel|
Never complacent about anything whirring round.
Since my new white wheel arrived I don't even have to press hard to shift metal so there's even less stress (mechanical and mental)
@SOD Good comments about perceived risk. Problem is that people just do not understand statistics - why else would Lotteries make money? It was good to read all the above posts; I guess the topic needed an airing.
I realise that my noddy 150mm bench grinder is a lot lower risk than massive, highly stressed wheels but, as has been said, it's no hardship to do a quick 'genuflect' when I turn it on. At this level, in the market, quality control and pricing will not be too much of an issue so I am probably on reasonably safe ground and the horror stories seem always to involve idiots and big machines (as with most things male).
I am particularly conscious of the wheel at the mo because I replaced the 'fine' grey wheel that came with the grinder 25 years ago with a white 'sugar wheel'. Such good value!!! It quietly shifts HSS quickly enough for me to get proper looking faces on cutting tools and it also took no time at all to re-do my wood plane and a chisel without overheating.
Dressing it was very satisfying and there is less vibration than with the old wheel, ever. I'm making a better rest for it which will improve things even more.
Money well spent.
I religiously stand to one side when I turn on my bench grinder and I see other people do the same on YouTube. I wonder how dangerous those things actually are, though.
I only heard of one specific case of a grinding wheel exploding and it was pretty horrific. A relative of mine had to rebuild a guys face - which was seriously damaged.
I am always pretty careful about using my wheel and would never hit is or push hard against it but what about the issue of using the side? The drill sharpening jig I bought seems to work only when mounted so as to tough the side of the wheel so what about the 'only on the front ' mantra that you seem to hear pretty regularly.
A higher apparent risk is with angle grinder discs which have various words of warning on them. But, on YouTube again, you see all sorts of antics used by some of the DIY 'performers'.
I never actually had a proper course on grinding and I know they are given to all professional too users. Is the risk real or is it just the fear of litigation that makes managers so careful about grinding? I am at least as careful as the next man (not the one with only one eye).
|Thread: Making Parallels|
Hey there. We at ME ain’t no masses.
But we do know that all biblical characters were white skinned and spoke in English. 😉
Hey there. We at ME ain’t no masses.
But we do know that all biblical characters were white skinned and spoke in English. 😉
OK I'm convinced. I'll do some shopping with Metals4You (??) or a better alternative?
A bit of a 'necropst' but the thread is still relevant and answers several of my questions. This post is pretty relevant.
There is one problem with the DIY approach and that is the need for a fair number of different pairs of stock to turn up in the limited selection I have in my shed. I already use two gash pairs and they are very handy but ti get work as deep as possible in the vise, I need more variety and that would mean ordering a number of different bits of stock - in steel - which could end up producing a lot of useless offcuts'
I sort of came to the conclusion that buying a set of cheap parallels is the easiest solution. But the problem is, I have the 'right' sized vise for my mill - the 80mm Versatile Milling Vise from ArcEuro (Which is very good for my purposes). The 80mm chuck width doesn't really suit the parallels that I can find on line. They are all more than 100mm long and I have already found that my Sealy mill is much tinier than its appearance suggests. The shorter axis means that things get in the way and an overhang of parallels gives no significant extra support.
So I am looking for some short ones (just a bit over 80mm. Can anyone point me at a supply? Anyone know of a source that's not Chronos, RDG, ArcEuro etc.? I guess there could be a far east s source but I don't know how to access it.
I'm surprised that such a useful item for miini Mill owners is not on eBay (not for me, anyway.
|Thread: Fly cutting puzzle WD40?|
A learning experience:
I am just coming to terms with using my flycutter and, to me, it seems to be the Milling equivalent to parting on a Lathe. It's scary to watch unless you get it right. When it works ok, you cannot imagine what the problem was, ever.
My first results were more or less just banging and rattling as the tool hit the side of the work and was because I started trying to make the tool like a turning tool. It is now 'obvious' that the tool slopes diagonally down from the holder but I failed to realise just how much. It is very hard to think in the 3D that's necessary for understanding cutting tools and I failed to realise that the two cutting edges for a turning tool are not the same two cutting edges as on a fly cutter. (The two operate nearly at right angles to each other). The more I persevered with this mistake, the worse it got. I now realise that the basic relief slope of the fly cutting tool is already provided by the holder. I was putting a 'heel' on the tool which was destroying this relief and giving me a very long cutting (hammering) edge.
My mistaken ideas were not helped at all by all the videos I watched because the guy shows a diagram. He then uses the grinding wheel to produce a beautiful face but then, 'abracadabra' he moves it and rotates it in the air and I'm totally lost. Which face has gone where? Despite having grown up as a 'formal' learner of theory using Maths, I have now joined the kinaesthetic school (learning by doing).
The shape of a milling cutter and the way it functions somehow makes more sense to me (now) as you can eyeball the tool against an actual flat surface better than the curved surface you have when you're turning on a lathe. As I increased the bottom relief, the banging eased up until it turned into more of a 'swish' of a scythe through grass. Sudden grooves and stalling (only a toy mill) seem to be things of the past now and I am working on 'that curve' to spread out the grooves from a pointy cutter.
The patterns that the flycutter (and all the other cutters) are quite disturbing as the illusion is that the finger smooth surface has deep grooves running along it. I guess that is largely down to a record of tiny vibrations - like a vinyl disc.
On the subject of raggedy edges, I was looking at this YouTube link and, although it is mainly about plastics, the principle seemed sound (and he demonstrated hi theory works - for him). The rake on the outer face of the tool seems to be very relevant for materials that are soft and weak. He says that a negative rake allows the tool to get right to the edge of the piece without being pushed out, rather than cut properly, and then the last bit is levered out by the wedge and falls off as an ugly edge.
|Thread: Slitting saw applications: limited?|
I guess I have suffered from the "get one of those and there will be no more problems" idea. A slitting saw is what it is and mine certainly does some things very well.
I can see that I was right about the 'experience' thing. Using the lathe is one way to go but the standard mini has no T slots so everything (literally) hangs on that funny little tool post fixing. A project to think about!!
Nah. The column will tilt +-45 degrees but best not to disturb that, so I'm told.
My mill is only a bit bigger than a toy. I think I could do with a reasonable extension to the quill but people will tell me no, I'm sure.
Perhaps I need to make a holder to make it possible to cut small bits on my Clarke bandsaw. That gives a good finish and everything's square. It's just a bit on the big side.
I have a mini lathe and a vertical table and I have actually managed to do some cutting that way but it's all very cramped, with the milling table stuck in just one place on the apron and there are so few available spaces for the blade and the workpiece to sit in order to make a useful cut.
I guess I could get a big diameter saw blade on the mill (a Sealey SM2502 Mini) but then the motor is only 350W and I don't think it could manage to cut with a big radius.
I find that it takes a lot of different jobs before I can suss out the best order in which to do things. Perhaps an angle plate could help me. Dang - more expense.
In my short experience of using a slitting saw I have been annoyed that, with a standard arbor, which fits right in tight with the quill of the mill, you cannot get into an awkward space and the 'nose' of the arbor means you can't get down close to the top of the work vise to take a thin slice off an already thin piece.
This may not matter with steel and aluminium but ablating loads of brass is an expensive and upsetting process. What alternatives do people use to cut without waste?
Experience and good planning are probably the answers.
Edited By andrew lyner on 03/06/2020 23:02:47
|Thread: DRO installation|
DRO seems to be getting cheaper these days (at entry level).
I am wondering about dro installation on my mini mill, in particular. There seems to be more room for mounting the scales than on my min lathe; I have enough trouble fitting things in and drilling small parts on the lathe, without interfering with the cross slide further.
Many of the cheaper systems warn that they are not water / fluid proof. I can imagine that could be a problem. (???) Also, I rather fancy a magnetic scale which could be cut to fit exactly. It's not always obvious which is which on the eBay ones.
I have a converted tyre tread depth gauge which fits (magnetic) on various parts of my lathe and gives useful ad-hoc measurements BUT it has a habit of suddenly going loopy and the display shows random numbers until the motor is turned of and on again. I could buy another one, of course, if it would solve that (interference?) problem - has anyone else tried making one? They're great value at about £8, iirc plus a couple of magnets. I have also seen digital callipers converted for the same purpose.
|Thread: getting MT3 tools to release from the taper on mill spindle|
I don't seem to be able to add a 'Like' to posts on this forum. Am I missing something or is the facility really not there?
That doesn't follow at all because it all depends on where both forces are applied. It is logically possible (not always practical though) to make sure that the two opposing forces are only applied to the taper and spindle. True, It would be possible to push against the top of the drawbar but, when there is room in 'that region' at the top of the spindle for extra threads and a sleeve of some sort, the forces could be balanced.
On another matter, people seem to be claiming that dynamic and static forces on a bearing would have equivalent effects. (i.e. bashing = pressing) That can't be true in general. Hitting one end of a linkage can produce very different forces than the maximum force from the hammer. Overcoming static friction is a matter of peak force whereas the amount of damage done is more related to the Work Done. The follow through from a heavy hammer will involve all the original Kinetic Energy of the hammer, long after the taper has been dislodged and the KE could end up being transferred into distortion (working the metal). A heavy hammer must be restrained from hitting the spindle after the taper has left it. Can we be sure of achieving that? A rigid puller exerts virtually no force, once the taper has moved by less than 1mm.
Impulse is defined as Force times time, where Work is Force times distance. Trying to reconcile these two things is a problem that you will find in sport, insurance claims and manufacturing Science. Finding the appropriate approach will depend on the specific application and involves suppressing intuition. Most of the race memory about these things in hobby Engineering is based on situations involving 'old materials'. Modern bearings are not made of old materials so it's not obvious that the optimal solutions are the same as they used to be.
Where does all this lead us? MT is not ideal but I wonder how it came to be so popular. Despite what experienced members have to say about it, the flaw is not enough to blight the whole stable of mini lathes with dodgy bearings that we should, according to local experts, all be suffering. It it really were a major issue then why is there not a source of suitable pullers advertised and available from a host of Eastern entrepreneurs? The puller is clearly a perfect solution if there really is a problem - perhaps better than the captive drawbar which is not an easily retro-fit.
There must be some strong feelings about, judging by the length of this thread. (Keeps a Forum lively).
I have a similar problem with my retro style Pavoni Europiccolo lever espresso coffee maker. That has a long lever which is 'balanced' by the column of the boiler. A design that's looked upon as weak and scary (a split in the boiler could spray you with boiling water) but which is still used and unmodified for decades. A strengthening mod would be easy to incorporate but it would spoil the whacky appearance, perhaps.
Whenever I hit the end of a threaded component, in order to extract it, I am worried about the longitudinal stress put against the thread - particularly when the thread may have been partially undone. No one in the thread seems to have considered this. Am I worrying too much? I am not King Kong but I have seen visible signs of a thread being distorted and also evidence that the feel of the thread changes as you go on and off the distorted section.
I appreciate that a draw bar is not a particularly vital part and easily replaceable but it does seem to be the poor relative in tool attachment.
So, basically we're saying that tools with an MT3 taper should be provided with a U shaped 'puller / pusher' which pushes the back end of the taper and pulls back the front of the spindle, thus avoiding any forces against the bearings. Sort of thing a chap could probably knock up with some beefy angle iron and a bit of imagination.
Sticking Taper could happen through bad luck and a small amount of corrosion (nervous sweat?) so you'd better get to it fellas.
It's so complicated to predict what happens during a collision. Masses and materials involved plus speeds are all relevant. Years ago I was tapping gently on a shaft and just managed to spread the end with the hammer. (Embarrassing! I had to take it down the road to a man with a fly press) A press / puller is favourite when there's something to supply the 'reaction' force. Not always available at the roadside, though.
At least taking out my draw bar and replacing with the wider rod takes the stress of the threads. I was impressed how small a tap would release the taper. The bar/hammer is about 300g. I could always put a brass end on it if I need to use it often.
I wonder how the pressure from the workpiece compares with the force from a drawbar. It's marginal in the tailstock of the lathe as the taper can slip round if it hasn't settled in convincingly. Some cutting operations don't exert a lot of force into the taper. I will try using minimal effort in tightening the drawbar in future.
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