Here is a list of all the postings Martin Kyte has made in our forums. Click on a thread name to jump to the thread.
|Thread: Possible Myford 7 safety issue|
An extreme example but I'm sure these guys would not appreciate being anywhere near anything that was earthed.
Quote " Arguing that if a machine is earthed it may make the situation worse is very questionable."
Absolutely not saying that but making the point that surrounding oneself with earthed metal surfaces does not neccesarily improve safety and can actually increase risk. Kitchen sinks are now no longer earthed for that very reason. Small kitchens allow hands to reach sockets and the sinks at the same time. It takes 2 connections to cause acurrent to flow so if one of those connections (the sink) is a high resistance path then less current will flow.
Metal pipework is no longer earthed. Plastic non conducting sections of pipe are common in houses.
The general philosophy is that if a metal box has mains fed into it via a cable then the box should be earthed. If it was an old Wolf metal cased drill then that would apply to the case and I would suppose everone would be happy with that. Attatching the drill to a metal stand does not increase the hazard.
I do however totally agrre with your comment "The first rule is prevention. So at no time should anyone come into contact with a potentially lethal voltage. "
To my mind having read the original post and John Haine's clarification as the motor is earthed to it's metal casing that is sufficient to protect the user.
Howard Lewis wrote "So: the single phase motor being resiliently mounted needs to be bonded to the rest of the machine, vis its baseplate. Otherwise a short to the motor frame will render it live." However as the casing of the motor frame is earthed it cannot be made live without blowing the mains fuse or in these more enlightened time throwing the RCB on the workshop electrical distribution system.
The above in my opinion is valid if the motor is the only part of the lathe connected to the mains where the rest of the machine is merely a complex bracket to hold the motor electrically speaking. Earth bonding is a question of interpretaion, sometimes helpfull sometimes not. In the case of the Myford resilliant mount single phase motor having a seperate earth bond to the machine could in some instances make things worse. Suppose that the eath bond to the internal casing of the motor were to fail and the case become live them a hand on the metal stand and one on the casing would be possibly fatal. A good ground in one hand and a good connection to live in the other with the current through the chest. If the lathe is floating however the resistance to ground is much higher and therefore less likely to proove fatal.
A rough guide is if a live connection to skin can likely be made then bare earthed metalwork is not good news. If all mains souces are remote the earth bonding is benificial. This is why there are different rules for kitchens as opposed to bathrooms.
|Thread: Soldering Electrical Connections to NASA standard|
Do the tin whiskers come from the solder or from the tinned tracks? Tin plating on boards being pretty much 100% Tin. I would hazard a guess that NASA gold plate everything destined to fly.
The point about moving to lead free solder for commercial products is not that anyone is at risk whilst handling or using leaded solder but that the amount of electronics goods currently going into landfill poses a significant risk of contaminating ground water. Why we should be junking such a large amount of valuable material is a separate question.
|Thread: Is this a dog?|
Yes, I'd vote for woodturning driving dog too.
|Thread: How to keep Paint Fresh?|
Try freezing it.
|Thread: four way toolpost with ratchet|
It certainly looks like a Myford 4 way indexing tool post.
Note to self, dig out my old one and measure the dimensions of the square.
Edited By Martin Kyte on 27/01/2022 22:14:03
|Thread: Is it possible to by "100% non-stick" spatulas for spreading glue? (ideally made from teflon/FEP)|
The main requirements are that the spatula should be flexible and very smooth. The peel strength of most glue is fairly low so with a flexible spatula the spatula can be peeled off the glue.
|Thread: New highway code rule.|
As an ex motorcyclist it took me forever to stop looking over my shoulder when pulling out instead of checking mirrors. Cycle lanes make me chuckle. The ones outside the Lab (both sides of the road) are used by cyclists travelling in either direction. So you can have two cyclists approaching each other on the same cyclepath. Usually one either pulls over onto the road or the pavement. It make it interesting leaving the Lab car park as you not only have to check for road traffic but for cyclists travelling either way on the bit of cycleway you are about to cross. But then it is Cambridge and we are reasonably close to the language school.
Edited By Martin Kyte on 24/01/2022 13:59:59
Edited By Martin Kyte on 24/01/2022 14:00:28
|Thread: Wire wicks|
Do wire wicks entrain grit ?
The main reason for using wicks is they deliver oil and leave the grit behind.
|Thread: What Did you do Today 2022|
As Bees pop up from time to time on here I thought you may be interested in this thermal image of one of the hives at the Lab. (Kept purely for enjoyment at honey)
|Thread: Are standard "M4" nuts & bolts normally fine or course pitch?|
|Thread: Engineering as Art|
I meant that that may be the case sometimes, but our system certainly operated sequentially maybe VuTrax had it's own plotter driver built in. I have no idea what my friends system used.
I do hope you realise I am just repeating the story. The intresting point was the tracer worked as she always had.
However our own plotter used for plotting PCB transparencies did follow the input file including redrawing lines where there were two lines between two points. That used to gum up the pens something chronic, so I'm not sure I entirely believe you Michael.
I would have some of the classic draughted pencil drawings from old engineering books on my wall. Inddeed some old books have pages missing where this has actually been done. Grimthorpe's treatise on Clocks Bells and Watches is a point in case. It is supposed to have a fold out drawing of the Westminster Clock (aka Big Ben,yes I know it's really the bell) but in most copies this has been removed and sold separately.
Not sure I would want any of the CAD drawings on the wall even the 3 D renderings.
On a slightly different track a friend had an interesting story back to the period where their company was transitioning from drwing boards to CAD. The employed a lady who had been a tracer to digitise the old drawings. Essentially clicking on the ends of lines etc and generating computer input. For printout they used an HP pen plotter which could do A0 sheets by moving the pens in the X direction and rolling the drawing sheet in and out to generate the Y axis. When the printed any of the newly digitised drawings it took an age as the plotter spent all its time drawing a bit and then moving to the other corner of the sheet and doing a bit there and so on. Things were plotted in the order of input. When she was asked why she had done thing in this way instead of systematically moving from the top to the bottom in one pass, she said that as a tracer, you had to do a bit and then do somewhere else whilst the ink dried otherwise you got smudges. That was the was she always did it then, so she just carried on the same when doing the digitising.
Edited By Martin Kyte on 12/01/2022 10:22:23
|Thread: Wind powered machine faster than the wind|
Do you really mean downwind. The land yacht travels into the wind and the clip is captioned upwind.
|Thread: drill sharpening jig or dedicated tool|
Under 6mm regard as disposable. I have several sets of drills. a best set (well 2 actually steel and brass). As drills get blunt they are relogated to the DIY category and are also fodder for regrind specials for plastics etc. If you don't have a cast off set you will end up using your good drills for iffy jobs, like using them in battery drills where they will never run true again.
|Thread: Building a Minnie|
I don't think so (re ambitions). It depends a little on how you like to work but there is no compulsion to employ a step wise approach to what you build. I started out , after building a simple weight driven clock, to build a 5 inch GWR King as a first loco. My logic was that was what I wanted and to build something simpler would leave me with a loco I did not really want and take a deal of time to build. I had already realised that the King was to be a very long term project and that skills would be obtained along the way by making various workshop tools and equipment.
I would say go for the Minnie and if you get to bits that are new to you such as cutting gears take some time out and build something else like the George Thomas geared bending rolls. Gives you the practice on the gears, makes a break from the Minnie and you wind up with a usefull piece of workshop kit which can roll your boiler cladding for you.
Hope these comments help.
PS I still haven't finished the King but as I'm now part retired things are speeding up.
Edited By Martin Kyte on 08/01/2022 11:37:34
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