Here is a list of all the postings Bill Phinn has made in our forums. Click on a thread name to jump to the thread.
|Thread: Problem with DRO's memory or with mine?|
Apologies for my necro-reply to this, Nigel; I've only just got round to giving it due attention.
I looked at a video corroborating what you say.
A problem I have is that, contrary to your and the video's description, there is no "ref" key on my DRO [see pic].
I'd hoped my manual might clarify what to do instead, but it doesn't really. On p.11 ["Methods of finding mechanical origin"] it says:
"Move the raster ruler to the position which is initially set up as the mechanical origin [not sure what this position is], and then enter into the select page of Segmented compensation. Choose Find_ZE and press ENT to the interface for choosing compensation method, press ENT the interior of digit display meter handles automatically. At this time finish finding the mechanical origin and quit the absolute co-ordinate system automatically."
It goes on, in a similarly cryptic style, with more instructions than I can quote here at the moment.
In order to try and get to the "Find_ZE" point indicated on p.11, I previously tried following the instructions on page 8 relating to "segmented error compensation":
1). "Move the raster ruler to the smallest end of the co-ordinate [not sure what is meant by that] and enter into ALE right-angle co-ordinate system.
The problem was that "Find_ZE" is not what came up on the display at this point, so I was unable to comply with the instruction on page 11 "Choose Find_ZE" , which I'd hoped might have allowed me to arrive, via an alternative route, at the outcome suggested by you and the video.
Any help would be greatly appreciated.
|Thread: A Certain Age|
A crucial difference is that Latin is what is technically known as a synthetic language, having a large variety of terminal word inflections carrying crucial information such as tense, number, person, gender, mood, voice, and case (there being six, arguably seven, cases), all of which can be a nightmare to learn but does allow for very flexible word order, whereas English is an analytic language, in which inflection plays a much smaller part (there are only two cases, for starters) and more reliance is placed on the use of things such as prepositions, articles [“the”,“a/an"] and a relatively fixed word order to clarify meaning.
One of the unfortunate ideas we’ve not yet jettisoned (and native speakers of all languages are guilty of this, as far as I can tell) is the idea that there are absolute canons of correctness that can be appealed to to establish definitively whether any particular way of saying something in our native language is right or wrong.
Such absolutism is fine when you’re dealing with a corpus language such as Latin, in which a finite body of literature is necessarily the ultimate arbiter of how we're permitted to say something in that dead language, but with living languages we're all collectively both legislators and arbiters of how our language can be used.
This doesn’t mean that in a living language anything goes (usage, ultimately, will determine whether something is generally accepted or not), but it does mean a prescriptivist outlook [“This is right/That is wrong] is on shaky ground, particularly when no allowance is made for dialectal differences that make, for example, "We was/He were" rather than "We were/He was" perfectly standard in certain parts of the country.
It’s worth remembering also that the Classical Latin we know of, being largely formal literature, is quite an artificial construct, and almost certainly doesn’t faithfully reflect the way Latin was spoken by ordinary people of the time.
Edited By Bill Phinn on 10/03/2021 17:59:35
Posted by Bazyle on 09/03/2021 18:55:06:Not one iota << note use of latin
It's Greek, strictly speaking.
Partly tongue-in-cheek, I'm sure.
Actually, most English study at university is a study of the literature rather than the language*. It shouldn't be, in my view, since "knowing" even your own language well requires a lot more than just habitually speaking and writing it; just as most people who can drive a car don't know much about what's under the bonnet, most native speakers of a language have only a superficial understanding of the history, morphology, syntax and signification of the words they're using. It usually also means they "drive their car", i.e. use their language, less skilfully or sensitively than they otherwise might.
*I exclude linguistics subjects, but then the focus of linguistics courses rarely confines itself to the English language.
|Thread: Silver Soldering Flux?|
Perhaps it is simply that in a busy shared workshop a pot of mixed flux can get contaminated very quickly, with grungy brushes being dipped into it etc.
I keep some Easyflo mixed in a small lidded jar. After not being used for a while a few drops of water gets it to the right consistency very quickly. There might be molecules of the stuff in that pot that have been remixed countless times, but it still works as it should. I keep a few paillons of silver solder in the pot as well. I know they'll be guaranteed clean when I fish them out and usefully primed with flux.
Edited By Bill Phinn on 09/03/2021 16:52:47
|Thread: Drilling & tapping for a screw whose major diam. is undersize|
Many thanks for everyone's replies, especially for the heads-up on the three different kinds of threads that are a close approximation to M5 coarse. The screws were bought new, yes, from a Chinese eBayer, and advertised as M5, but I suppose that's no guarantee of conformity.
Howard, it is definitely not the drill cutting oversize, but thanks for mentioning it.
I have just bought a single BA2 tap off eBay for £2, and will see how it goes. Given the fact that I have another unexpected solution, explained below, it will be interesting if nothing else to have a go with the BA tap.
The unexpected solution is that the screw part of the thumb screw and the knurled nut are in fact "loctited" together.
This wasn't ideal anyway given that the screws are going to be repeatedly heated in use, and it now allows me to disassemble them and use either a known high-temp loctite or [what I'll probably use] silver solder to join a piece of M5 stainless studding in to the original thumb nut.
I've just heated two of the screws to a dull bronze colour and this allowed me to disassemble them easily with the help of mole grips on the screw and a leather-gloved hand on the knurling. Interestingly on both of them the part of the screw that is inserted into the blind nut has a 2.5mm hex recessed into the end. Possibly the hexes were originally intended to allow the screw to be tightened down into the nut, but not wanting to have to trim off the ends afterwards they just inserted them the other way round.
If I'd known the screws were going to be this undersize I'd have just bought the blind nuts rather than pay almost twice as much for the full screws.
Thanks for the suggestion, Michael. I'll have to price up a tap.
Some solution at least will be needed, I think: I have twenty of the thumb screws at £1.25 each.
Thanks for your suggestion, Emgee.
I don't think I can safely do that; the finished item will be subject to repeated heating of 150 degrees C or more.
Edited By Bill Phinn on 06/03/2021 19:36:37
Apologies if this rather elementary question has been answered before.
I've recently bought some knurled M5 stainless steel thumb screws for a project. The holes they will go through will be in brass.
An unsatisfactory aspect to them is that their major diameter comes up rather small for M5, being typically around 4.65mm [and in a few cases even smaller]. This means that when I drill 4.2mm and tap with an M5 0.8 tap, there is a lot of slop between the male and female threads.
Logic tells me that, to reduce slop, apart from drilling slightly undersize I need an M5 0.8 tap with a smaller major diameter than is usual, but is this realistically obtainable? If not, is there a practicable workaround?
|Thread: Paillon when Silver Soldering?|
Paillons laid on before heating is much more common than stick-feeding among jewellery fabricators. One of the advantages of it for jewellery fabricators is that a very precise amount of solder can be applied to a joint in circumstances where an excess of solder would very probably mean spoiling the contours of a piece whether it was left on or cleaned off.
Experienced fabricators executing multiple small solder joints on a single piece tend to use a slight variation on the paillon laid on before heating: they ball up a paillon on a soldering block by heating it, pick it up on the end of a flux-dipped solder pick or tweezers, and then apply it to exactly where they want it just before the part reaches flow temperature. This method combines the advantages of stick-feeding and paillon laying: it carefully controls the amount of solder on the part and stops the paillon bubbling out of position early in the job.
You can see this technique in action in various parts of this video of the goldsmith Kevork Gurunian at work. Try 24.15 if you want to go straight to an example of it.
Edited By Bill Phinn on 06/03/2021 00:46:18
|Thread: Help needed to lift bandsaw curse.|
Alan, technically it was both, though the faultiness was almost certainly courier-induced rather than the manufacturer's doing. Amazon UK were also hardly blameless for sending out a saw to a UK consumer with a two-pin plug. The foul-up with the return was the icing on the cake.
I would have given a Femi another go if either Amazon or Stakesys had had a replacement in stock, but both suppliers were clean out for a long time. After a brief window of availability in the New Year, Stakesys are now out of stock again, not just of the model I bought but of virtually all 230v versions.
John B., it's useful to know how common problems of this kind are with bandsaw blades. For the record, the blade that cut the piece of brass was fresh out of the box and the teeth were definitely not brought into contact with the brass until the saw blade had reached its operating speed.
John (Breva), I have checked the first blade, which is currently removed from the saw; there is indeed a very slight though gradual dip around the weld line at the back edge of the blade.
Many thanks, Jason and John. Good to know this strange crop-circle-type effect has such a simple explanation.
Since this problem is with the second blade and the first is already known to be defective, I take it this means that both the blades supplied with the saw are a bit sub-standard.
Tuffsaws replacements beckon fairly soon.
John, could you explain this further? The brass was cut lying flat, so I'm not sure how a few bad teeth could have caused those marks even if there were any, which by all appearances there aren't.
Thanks to everyone for your replies.
Howard, thanks for that information. I think my blade is set up pretty well even without the use of a DTI, but a DTI test of the kind you mention would certainly be useful, I'm sure. I'm also pleased with the accuracy of the cuts as things currently are. Time will tell whether the blades are long-lived in my hands; after a couple of dozen cuts in steel I can't detect any appreciable wear yet.
Keith, I can say with some confidence* I wasn't cutting with excess downward pressure; if anything I was holding the saw up in the cut; what's more, on other tests, whether I held the saw up or let it sit on the work under more of its own weight made no difference to the downwards kick. I did also mention that a change of blade improved the situation considerably, and downward pressure was the same (i.e. minimal) with the second blade as with the first.
* My right arm [the arm that was holding the saw] has functioning biceps but no functioning triceps or deltoid muscles [among others], so pressing down even remotely firmly with my right arm is something I'm physically incapable of; the outcome of a bit of a bad show on a motorbike many years ago.
Thanks for the further replies.
Robin, disturbing to hear about your Axminster saw - puts my problem in perspective.
I'd got Tuffsaws earmarked even before the present saw arrived.
Sadly, at the moment, I'm getting the following message on all pages of their website:
"Due to experiencing higher than usual levels of orders, the website is currently offline while we catch up but will be back up shortly.
Please check back later or email us at firstname.lastname@example.org"
Martin, yes, the third one is top right.
I suspect my problem is a combination of the first blade having a marginally too thick weld area and one pair of guide bearings [before and still] being marginally too close together.
If I can loosen off the screw going through one of the bearings that are too tight, will this allow me to retighten the screw with a bit more clearance? I ask because I can't really get to the bearing screws with the saw mounted on the pivot arm, and after the trouble I had mounting it in the first place [having to do the work practically one-handed] removing and remounting it isn't something I look forward to with relish.
Martin, good question about the blade guides. The gap between the pair of bearings distant from the cut direction is noticeably greater than the gap between the two bearings on the other side of the gap. Measured with a feeler gauge it is about 0.05mm wider. The blade inserts easily between these two bearings and is piggishly tight between the other pair. Not sure if this is how things should be, or how adjustable the bearing positions are [I suspect they're thread-locked; EtA: tried to undo one screw - tight as hell, and head of screw not very hard, so gave up for time being].
Sorry, I'm not sure what you mean by a guide pushing down the blade.
Edited By Bill Phinn on 28/02/2021 22:16:33
Many thanks to everyone for your replies.
I think the blade is almost certainly the problem, as Jason and others with experience of these things clearly sensed.
I took off the blade used in the video, located the weld seam and emeried it as smooth as I could get it, even though it was pretty smooth to begin with.
After refitting I expected at least some improvement, but there was none; it still jerked downwards disconcertingly. [In the video the jerking and clunking is more noticeable in the last half].
Fortunately, Aldi supply two blades with this saw [M42-grade steel, so perhaps a bit better than bargain bucket territory in their material at least?]. I fitted the second blade. There is a slight detectable deviation downwards once per rev., but this is much less than with the first blade, and there is no audible clunk.
As for cut quality, I've uploaded a couple of photos of steel bar showing the difference between cutting with the bar flat and cutting with it standing on edge, as initially. Lying it flat produces an obviously better cut.
There are still two minor issues. The picture of the brass bar [in the first image and 3/8" x 2", I think] shows the first: the two short patches near each end of the bar. I can't detect any difference in surface height with my finger at these points, so I'm not too concerned by it, but does anyone have a suggestion as to why these markings have occurred? There is nothing on the surface of the bar either side to explain their existence, and further cuts produced exactly the same result. The bar was cut lying flat.
The second issue is that now I have shimmed the vice on one side with washers [around 1.25 mm thick], the plastic guard on the inner side of the saw slightly fouls the angled side of the vice at the bottom of the cut. I can probably resolve this fairly easily, but why the clearance between the edge of the vice and the body of the saw has to be so small I don't know.
John Baron, there are no missing teeth.
John Haine, if you click on the second link in my opening post you should find my post about the Femi on that page.
Ady, the user manual shows the blade tension lever pointing almost vertically downwards when the blade is tightened according to the instructions ["to the stop"]. Are you saying it would be OK to use the saw with the lever backed off part way? I will back it off when not in use.
After buying an Aldi Workzone bandsaw in 2019 and deciding to return it because I felt it wasn’t good enough for my needs
I some time afterwards decided I couldn’t live without a bandsaw so bought a more expensive Femi model, which, in some ways, was even more disappointing:
This too was returned (and subsequently lost by the courier, though that is another story).
Feeling I still needed a bandsaw, last week I bought essentially the same Aldi bandsaw as before but this time branded under the Scheppach name.
Like the first Aldi saw, out of the box the Scheppach would not cut perpendicularly to the vice/base. However, I managed to correct this by simply shimming the far side of the vice slightly. It now cuts perfectly square, even when what is being cut is something as thick as a piece of 4x4 timber.
In spite of my initial elation, I soon realised that my bandsaw curse has not yet been lifted; there is a very disconcerting clunk as the blade kicks downwards into the work every revolution.
You can judge for yourselves in a video a friend of mine has uploaded for me. For the record, I am cutting 6mm x 20mm hot rolled mild steel bar, the blade is fully seated on the wheels and bearings, properly tensioned, running on speed 2 out of 6, and not by any means being forced into the cut. There is no noticeable weld seam on the blade and no obvious (to me) reason why it kicks downwards.
Whether the surface finish I’m getting is anything to do with this kicking downwards I don’t know, but I do know that the surface finish on brass, aluminium or mild steel is poor. (Attached photo shows 6mm x 20mm hot-rolled steel bar).
Any suggestions on how to cure the downwards kick and improve surface finish would be greatly welcomed.
My disappointment at being unable to make use of this supplier here in the UK is slightly tempered by the fact that some of their products seem somewhat dearer than I can get them in the UK [medium and high tensile threaded bar, for example*] and sometimes the selection of metric items [as opposed to imperial] is, as you'd expect, quite scanty.
*EtA: Anyone interested can compare the two below.
Edited By Bill Phinn on 27/02/2021 23:30:09
|Thread: Countersink bits|
The range of Sherwood single-flute csks from Zoro are excellent in performance and value.
Alpen three-flute csks give very good performance as well though are a little pricier.
Machine countersinking shouldn't cause chattering as long as you keep the speed and downfeed pressure low, and have good stiffness in the set-up. I tend to use Vactra no.2 as a lubricant, when I do use a lubricant.
Edited By Bill Phinn on 27/02/2021 12:46:23
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