Member postings for Steve Skelton 1

Thanks David/Jason. I tend not to use the grid options it was more the other tools in the sketch options I was more interested in and what they do.

Jason, how do you get the "sketch options" on the 2D Sketch Ribbon

Thanks

Steve

Jewelers rouge mixed in a little water and painted onto the surface you do not want the solder to be on has worked great for me - no issues with solvent or going off over time. Is removed easily afterward.

Chris - yes I am with you on that - shall pay more attention!!

Chris,

I think you are misinterpreting what I have written. I agree with all your statements up to the RCD being of no value. A current imbalance of between 15 and 30 mA will trip any final circuit that is 30mA RCD protected (and working).

Robert is right, if a 30mA RCD is supplying a Class 1 appliance and then you or an earthed object touch exposed conductive parts on the appliance and it causes a differential current of greater than 30mA between the phase and neutral legs at the RCD it will cause it to trip. Due to internal resistances of the appliance it is unlikely that there would not be a 30mA imbalance in the phase and neutral conductors back at the RCD.

Chris, yes it certainly would do no harm to put a plastic section downstream of any outside tap supply.

The fitting of an insulating section to an incoming water pipe would, I have thought, be counter-productive on the failure of the neutral supply to a PME property. If any supply ie lighting, is switched on then the neutral and hence the earth cabling would become live. This would then cause the metal casing of all appliances and other earthed metallic class 1 fittings to rise to phase potential with the obvious result if touched whilst standing on a potentially earthed floor.

If the water pipe is connected to the earth (via bonding) then the fault current is likely to pass down the water pipe through the class 1 items on the water/heating circuit and would likely cause disconnection of the over-current protection device on that lighting circuit – this would (if the only circuit switched on was lighting) very likely disconnect the phase from earth I.e cause the fuse/mcb to blow.

Admittedly if a number of higher amperage circuits were still connected (through appliances that were turned on when the neutral was lost) then the resistance of the water pipe may not be adequate to disconnect all of the circuits.

The solution to all of this is to fit RCD’s (or RCBO’s) to all circuits. I wonder how many people regularly test their RCD/RCBO’s????

As a matter of interest, a company I have dealings with that test RCBO’s and RCD’s say that up to 10% of the units they test fail – even some new uninstalled ones have been known to fail.

Can you please quote a source for this Emgee i.e. the regulation in BS7671- It is not something of which I was aware.

Rowan, try searching for "PVC batten" you may find what you are looking for.

Steve

Henry, to measure current in a cable you have to separate the phase from the neutral which is why you will not find a device to measure the current in a 3-core cable.

When in the trade I used to have a plug and socket with the three short cables separated in order to accurately measure the current draw - I could also measure any current leaking back to earth through the cable.

The plug-in adapter units work OK but are not particularly acurate but do have data collection options.

This is something I would be interested in myself. Have you tried a Google search on "best oscilloscope computer interface" it does yield a numer of options with reviews

John, I suggest you should call a Gas Safe registered plumber and ask them to do a gas tightness check. They will put a manometer on your meter, turn off the supply at the meter and monitor the pressure in the house gas line. If it drops with all appliances isolated that will tell tou that you have a leak in the pipework system. I would caution against contacing the supplier as they will insist you turn off the gas at the meter and not allow you to use any gas appliances until all the system has been checked. The gas tightness check will take about 5 minutes to perform.

Steve

Edited By Steve Skelton 1 on 06/09/2022 20:07:33

Dave, Natural gas IS lighter than air, I think you are confusing it with bottled gas, propane and butane, which are both heavier than air.

Steve

Nigel,

There is a lot of good stuff on here, however, I think you are approaching 3D CAD with the wrong mindset, let me explain.

I was in a similar position to you. I had come through learning to use a 2D CAD package, gaining a reasonable 2D proficiency, enough for what I needed to use CAD for. I had been using 2D CAD for about 25 years.

When I retired bought a 3D printer for a specific task which it did admirably but then started to think, what if I could design stuff and print it myself.

At the time MEW started the 3D CAD series with Alibre Atom3D so I took the free trial and started on it. It was an absolute disaster despite me following the tutorial in MEW. I kept tying myself in knots because of all of the 2D experience I had. Then I had a lightbulb moment when I read somewhere that said words to the effect of "forget everything you have learned about drawing and think that you are trying to machine a lump of metal and what you would do to it". Then it all started to make sense.

I find when making a 3D CAD drawing that you are either adding or taking away material with a positive or negative extrusion and make sure you are doing it on the right plane. You have to make a number of sketches, one for each separate machining process you are performing on the part you are producing before the positive or negative extrusion.

I would not profess to be an expert, in fact, I am far from that, but I have been able to produce everything I have set out to do so far, maybe not in the most elegant way but at least it has always worked.

I have no commercial interest in Alibre or know anyone connected with it but I find that it is simple to use once you have grabbed that first fundamental that it is nothing like 2D CAD and it is just about making a sketch, extruding it into a shape then adding or subtracting other extrusions to it via other sketches. It really is so simple - I think you are overcomplicating it and are taking all of your 2D experience into producing a complex drawing rather than using simple sketches to make a complex object.

Others may disagree with my views. I almost gave up with 3D but now find it useful and straightforward, but what is most important, it is satisfying and rewarding when you produce something.

Steve

Hi Ches, I only used the vice once - for the other holes I held the jig in one hand whilst holding the drill in the other so it will not be a problem having to find some way to clamp the jig.

Steve

Thanks everyone for your help.

I bought an off-cut length of 38mm polished stainless tube and manufactured a crude jig out of a lump of oak I had lying around.

Using a Dormer split point A108 drill in a Bosch battery drill on slow speed with a lot of pressure, along with CT-90 cutting oil I had no problem in cutting a number of 6mm holes in the tube.

So all I have to do now is to take all the kit with me and try it in situ (in about a month).

Photos as below:

SOD,

Three-phase RCD's work in exactly the same way as a single-phase RCD.

It does, however, have four terminals one for each of the phases and the neutral.

Due to the 120-degree phase rotation if all the phases are balanced then there is no current flowing in the neutral but if any phase is pulling more than the other two phases then there is an equal current (to the imbalance) in the neutral. The three phases are wound around the sensing coil as if they were one phase, but obviously insulated from each other.

Steve

Hopper I had thought of that and even using a diamond tile cutter as the main cutting device but felt it would be too slow.

Sorry for the delay in getting back.

DC31K and David-Clark 1 like the idea of a wood block, I was originally thinking of 3D printing something but think that would not be robust enough.

Noel I am also thinking a centre punch may not be a good idea, as Paul points out work hardening on a minor scale may result.

Peak4 and old mart - this is what I am planning to do.

I have some hardwood blocks kicking around in the shed so will experiment with them using a sharp drill (I cant use a centre drill as it would need to be long enough to go through the wooden block) using slow speed and maybe flooding with cooling water as it will be done outside where water will not be a problem.

I will try on some scrap SS and see what happens, I cannot do the actual job until May but wanted to get ahead of any likely problems.

Many thanks

Steve

Looking for some advice please.

I have to drill a number of 6 mm holes in polished 316 stainless tube which is 38mm diameter and 1.5mm wall thickness. The added complication is that it is nowhere near my workshop (and power) and will need to be carried out using a battery-powered drill (although powerful).

Would I need to use a pilot drill first? How to start without skidding all over the surface – center punch start or a clamp-on guide? What spec drill bits – I am worried that by using high cobalt drills it may be difficult to prevent them shattering using a handheld drill. Obviously need to drill at slow speed and use a cutting fluid but has anyone got any specific tips.

Thanks in advance

Steve

Certified 1.5mm^2 flexible cord has a 16 A current carrying capacity at 230V AC so should be adequate for the purpose. I suspect the unit would overheat before the cable did.