Member postings for Clive Foster

Is yours the type of chuck having the jaw guides made as separate steel inserts fitted into grooves in the body rather than the usual style where the guides are directly machined into the body?

My 160 mm 3 jaw that I bought around 30 years ago has that style of jaw guide.

If I recall correctly the instruction leaflet had some details on what to do if a jaw was a touch tight. I put the leaflet somewhere safe and might be able to find it if it would be of any direct use to you..

Clive

Oversimpliying. In the limit the wall thickness around the thread only needs to be great enough that the thread shears off at the base before the wall cracks and shears.

Given the very non-linear load distribution associated with "pin in a hole" configurations where most of the load is carried close to the open end odds are that a wall thickness of around 3 times the base width of the threads will suffice.

Out in the practical world it seems extremely rare for a threaded pipe or tube to fail before the thread itself. Some of the standard pipe and thread configurations leave what, to the naive observer very thin walls.

Clive

Michaels last post in yet another example of how hard it is for older penguins like me to keep up with the price performance ratio of modern electronics from China.

These days a proper engineered solution can often be gotten for less than the simpler DIY, minimal discrete components, solution that used to be all that ordinary folk could afford.

One minor issue is that there are reports of the "LM2596" chips in cheaper examples being re-badged "LM2576" versions. Fundamentally the same but running at a lower switching frequency, 50 kHz rather than 150 kHz, which generally matters not at all but efficiency may well be lower. Re-badging has apparently been worth it because the 2596 chips can be sold at higher prices than the 2576.

Hardly seems worth the effort to me but the economics of mass production, especially Chinese mass production, make my head hurt.

Clive

Lever style indicatoirs need to be very free moving over the full range to be satisfactory.

Any friction in the pivot due to corrosion or abuse will make them at best hard to use and at worse useless. There is a hair spring in the movement that is important to correct operation. generally either unobtanium or, in the context of ordinary guy pocket depth, unaffordable to repair.

Using one that "sort of works, usually" is a truely miserable experience, how do I know.

New import from a reliable supplier isn't silly expensive for something that needs to work well. £40 (ish) from ArcEurotrade.

Or you can usually find a Verdict in good order, with accessories in its case for £30 (ish).

Facebook Marketplace can surprise you too with things close enough to go and look at, asking for things to be sent is just too unsafe.

Clive

R4 simply has to be sized to carry the LED string current, plus a bit more to set the Zener safely in its operating range, with a nominal 9 volts across it.

But a fiver or so will get you a DC-DC 12 volt to 3.3 volt step down converter off E-Bay which will be rather more efficient than a resistor and zener set up.

Or you could use a linear regulator IC such as the venerable LM317 et al.

Back in the day I did a similar job, albeit 12 to 6 v, using a voltage controlled PWM oscillator, power transistor and decent size capacitors. Stiil have the circuit somewhere. Quite simple but I'll bet its not cost effective against an E-Bay special DC-DC device.

Clive

Jelly

Interesting links to the Kitagawa collets.

I'd not seen that style before. Presumably having the resilient blocks lets the collet cover a little more range to easily accommodate material tolerances by driving it a touch past its natural spring open position.

I use 5C collets so its a bit less painful to bin a suspect one than when dealing with more professional, production level, systems. But not springing open properly is always the first sign that poor holding power and other issues will soon surface. Heaving on the handwheel to get a weak collet to hold gets old fast.

Anyway who in the home workshop is set up to properly evaluate whether collet performance is up to specification? Or even do jobs that really need collet capabilities. Mine come out when thats the most convenient way of doing a job, the extra accuracy being mostly a nice but unexploited thing. Not having to worry about a big chuck wizzing round holding a small job is, um, nice. I guess that generally applies to most home workshop folk.

Clive

As Andrew says the 163E collets are dead length and don't move. They rely on the natural spring of the collets to open them against any frictional forces in the mount when the closer is released.

Old collets get "tired" after long therm production use and may not have enough spring to self open as per specification when mounted.

Old collet mounts do wear which again may increase the opening force needed.

The system is much more heavily engineered than you might think at first sight. Everything has to be right. But when it is the results are very durable and very accurate. When it isn't. Nightmare.

Jacobs Rubberflex versions have resilient inserts between the collet fingers to permit greater collapse range and, incidentally a bit more opening effort. Sounds like Jelly has a sort of shop-bodged version. Hate to say it but if his collets need the extra spring of the rubber they are passed their sell by date and objectively scrap. Even if they still appear to work OK. Life is way too short to futz around with misbehaving collets. The Jacobs version has the rubber bits bonded in. Not a pretty sight when coolant and time eventually degrade things to failure.

Clive

An effective way to avoid inadvertent speed switching whilst the VFD is running would be to use one of the mechanically interlocked contactor units used in forward - stop- reverse systems. With these the "on" contactor moves a mechanism preventing the other contactor from turning on. Need to use the stop button first to relase the latch before the other speed can be selected.

The one I got for when I finally finish sorting my American style vertical opening bi-fojd garage door was about £40, I think.

Clive

Jelly

Good points about the effects of improved workshop lighting on the need for machine lights.

However as I've utilised the space above both my lathes for shelving to store occasionally needed things freeing up the more accessible shelves for regual use items I cant get entirely satisfactory lighting from general distribution and need machine lights. Undershelf lights don't really cut it for me. Being able to point a machine light exactly where I want to see is very handy.

As eems to be the norm in space constrained workshops my Bridgeport lives canter-corner so needs a machine light to supplement general distribution. Again being able to get light in just the right place can be very helpful.

One oft overlooked benefit of a machine light is that it can be wired to come on immediately the machine power breaker (or switch for baby machines) is turned on. This gives a positive indication that the machine is live and iwll start up if the "go" button is pressed.

Given the inevitability of interruptions in the home workshop this seems a useful safety measure.

From me that particular advice as a bit "do as I say, not do as I do" as none of my machines are so wired. Instead mine are fed via "yellow body and red lever" Lewden breakers mounted on the wall in highly visible positions. It is immediately obvious to a casual look whether a machine is live or not.

Clive

Yep, certainly was one. Its irritating when one takes the trouble to carefully craft a reply in the hopes that it may be of general use to folk with similar issues and the thing disappears.

Especially so when you realise that you should have saved your bit for future use.

Clive

Running a motor on a VFD at less than the nominal voltage required simply reduces the speed at which things go into constant power mode iwth a pro rata reduction in power at the rated speed. I suspect that for most of us with industrial workshop sized machinery the loss of power will not be noticed. We generally just don't drive large cutters or large work at high speeds. If we do go fast its usually a small cutter or small job so inherently needing less power.

As usual Inverter Drive Supermarket explain running at less than norminal voltage is a way that normal folk can understand.:-

**LINK**

https://inverterdrive.com/HowTo/240V-Supply-to-a-400V-AC-Motor/

Clive

John

Basically you can't simply convert to low voltage delta to use a VFD.

As drawn the plate shows a two speed 440 volt motor. Changing between delta and star merely alters the speed.

To connect in double delta to run off a normal 220 volt VFD, as described earlier by Robert, you need access to all the 12 ends of the 6 windings. Realistically that is a job for a professional who knows how to make sure the windings are correctly orientated. If all the wires do come out to the terminal box its pretty simple for a pro who has experience in such things. 15 minutes perhaps so if there is decent rewinder locally it might be worth asking.

Clive

Robert makes an excellent point about relative costs of a new commercial rotary converter relative to several VFD boxes. As he says break even costs for a new converter against new branded VFD boxes is probably around 5 or 6 machines. Rather more if an unknown name import from a box shifter is acceptable.

For minimal complexity if you don't need the infinitely variable control of a VFD, a feature rather more attractive in theory than practice in my view, I like the Eaton DE1 series. These are made as a replacement for old style contactor controls and are about as close to drop in as can be. Just find somewhere inside the machine stand for it. That said I'd probably set up as a two speed device to, for example, halve the steps between belt positions on a lathe.

Going back to Johns motor it only has 6 connections so cannot be set up in double delta with windings in parallel. Doing so would reverse one of the windings in relation to its parallel connected mate which isn't a good thing. You need 12 connections, one for each end of each winding so the windings can be correctly paired and phased. Despite knowing how its done that's not something I'd care to try as its very easy to get in a mess.

Clive

Edited By Clive Foster on 28/10/2022 10:20:32

DC31k

I'd always understood that when dealing with aerospace components it was a general rule to positively mark any sub-standard (or fraudulent) components discovered in a manner than prevented them being inadvertently used should they re-enter the supply chain. Obviously the parts have to be passed back to the purchaser so and investigation into what went wrong can be mounted.

Presumably the heat treatment people would have known these were aerospace parts and would have dealt with them appropriately. Bottom line is the results indicated that something had gone seriously wrong and that there was no way the stainless steel parts could have been up for any job that the correct, tool steel ones, needed to be specified for.

Robert

I don't think the procedures actually covered wrong material. Sub standard or incorrectly treated material certainly. But flat out drawing the wrong bar from stock no.

Something of a "no one could be that stupid" issue. However stored, drawing the right material for a job is so fundamental to any metal working shops business that it almost has to be assumed that the firm will have ways of getting it right. Ultimately you can't specify everything.

Seems that a more robust approach would have been for the bar supplier to have permanently marked the relevant type, batch and certificate number on the bars. Then FMC could have been required to use only marked material from the same batch or at least having equivalent certificates. Given that 8 bars f new materils were insufficient to make the number of parts ordered its an odds on bet that FMC had a bar in stock which they planned to draw out and use to make up the numbers. Objectively fairly shady but something that could have been gotten away with if the right bar were pulled.

Bottom line is that FMC corporate culture wasn't really up to aerospace demancds.

Clive

Edited By Clive Foster on 27/10/2022 19:27:29

That report was an interesting read.

Shows the lengths proper manufacturing concerns go to to get things right and how errors can stack up to defeat the system. I guess the folk involved in setting the procedures didn't envisage that completely wrong material would have been used.

Dangers of modern automated and semi automated procedures set-up by people who know I suppose.

The "nobody would be that stupid" or "any person with experience would spot that" assumptions. When setting up such procedure its often hard to realse that the person doing the work doesn't have your experience and knowledge. Maybe more, may be less.

The one thing that did surprise me was that the pins that failed testing at the heat treatment firm were simply paint paint marked rather than destructively cut. I'd have expected an angle grinder cut or similar as the heat treating firm would surely have been aware that this material was seriously out of specification. I'd have thought that getting wrong material was something that happened often enough for the heat treaters to have robust procedures.

Clive

Rich

Looks to be right.

Crafty way of exploiting the double width gear. Fitting a conventional compound gear with the 127 conversion gear is essentially impossible.

After doing the conversion it would be wise to make your own version of the gearbox data plate with the new thread and feed data on it. Laminating a standard paper printout in plastic with one of the inexpensive devices works well and lasts for many years on a machine. Oldest one I have is well over 10 years old and showning no degradation.

Laminators are well worth the relatively modest cost as they make producing durable wall charts et al easy. Ace for making things proof against oily fingers too. I often printout sections of workshop manuals and similar for on the job reminders. A4 is good enough for most things but I have an A3 one for wiring diagrams.

Clive

Edited By Clive Foster on 26/10/2022 08:48:16

Curiouser and curiouser. The Y/YY marking means that both low voltage (220 V nom) and high voltage (440 V nom) are connected in star rather than delta / star. I believe there are efficiency and torque gains to be had from this set up.

Relatively low full power duty cycle implies it may be intended for something like an elevator running in short bursts whilst needing plenty of oomph to get things started followed by lower power running to keep things moving.

See the link Ajax posted :- **LINK** , https://www.wat.com.tr/baglanti-en/

but look about three screens worth down the page where it shows the Y/YY links.

A vector drive VFD will work well in low voltage mode. As always vector drive attempts to directly limit the current to that needed to provide only the drive power demanded rather than relying on the motor to self balance forward and back EMF.

Clive

5/16 will work fine and allow a little room for a release spring.

From what i've seen normal British practice was to make the bolt pretty much as large as would fit in the space and not use a release spring. Common to need a quick donk to release. Especially if the last guy to lock it was channeling their inner gorilla!

The angle on the end determines the force distribution. Following Alains' photo steeper angles push more force outwards to the main casting and shallower ones put more force along the clamp thread. With steeper angles you really don't want to do things up any tighter than needed as the outward force rapidly becomes enough to jam everything up solid.

It is said that shallower angles aren't as effective.

But I've never seen any sensible engineering explanation.

I imagine its like everything else in engineering. So long as the basic concept is workable the effectiveness in practice is down to how well the details have been handled. Careful engineering oif a theoretically not so good concept beats slap dash implementation of a theoretically better way every time. Good enuf is good enuf.

Clive

Not really.

Lever types, originally direct acting and later the modern "fast screw" style, were always the economically priced option. Consider the Unique to explore the insanely cheap possibilities.

But they are fundamentally null indicators so the change in accuracy with probe angle isn't of great import. Verdict developed the pear shape end to largely compensate for such errors. But the measurement range is inevitably small.

The rack and pinion drive used on plungers gives much more range of measurement and, if accurately produced consistent sensitivity over the whole range. Hence it can be used as a reliable measuring device. But the quality of workmanship needed inside has always made them relatively expensive.

There are ways of geometrically compensating for the arcuate movements inherent to the offset lever accessory devices such as those designed by Howard Hall. Although such can be effective they fundamentally rely on first set-up being with the offset lever largely perpendicular to the plunger stem.

In practice its generally considered less than ideal to use a plunger indicator over any extended range. Naturally such use may be quite adequate in many applications.

According to the Inspector Meticulous Union Rules objectively correct practice is to restrict measurements to around ± half a dial.

Fundamentally the proper home of a plunger indicator is in a stand checking variations in production parts, or samples thereof, to verify that factory output is within tolerances. Long travel just makes set up easier and helps get round extraneous lumps of casting et al.

Although a plunger indicator can be used as a decently accurate linear measuring device over its full range there are certain caveats associated with such use that need to be understood when seeking to fully exploit the potential accuracy. Which in general are at a level that is of no import to the work folk like us do at home by such methods given sensibly careful set-up and handling.

I absolutely agree that there are better methods when dealing with longer travels.

Back in the day the firm bought me some uber expensive, optical grating based, Hiedenhain probes when long travel plunger indicators couldn't hack it. The boss figured the probes were worth more than I was!

As is so often the case with tricky measurements. Carefully considered breaking of "the rules" works just fine if you've taken the trouble to understand the rules in the first place.

To quote (who?) :- "Rules are made for the guidance of wise men and the obedience of fools."

Clive says :- "It's hard work becoming wise and makes my head hurt. Most of the time I get along just fine being a fool."

Clive

Although past posts on this topic are very useful the market is still in considerable flux. Not only does the best price/performance ratio of the various options keep changing but newer and, possibly better, solutions keep arriving.

Case in point are the down-lighters mentioned by John Doe 2. Around 12 years ago I used GU10 fittings with 240 V led bulbs for what I suspect are similar duties. Best at the time. In the intervening years the most appropriate solution for that job, which wasn't necessarily tied to using down-lighters, has changed at least 3 times! Probably more if I'd really followed the market.

Clive