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Member postings for Martin Kyte

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: Chimney flue temperature
20/01/2017 10:03:41

Oh and it works 'tother way about in the summer.

We also have 4 deep well heat pumps. Good innit.

Martin

20/01/2017 10:01:22

If I was starting from scratch and building the whole lot myself I would use a 4 wire Platinum resistance thermometer with a local interface chip to either Bluetooth or wired serial comms with the wired connection out of preference because that way I would not have to change batteries.

I'm staring at a project I have on the bench at the moment which uses just such a set up. RTD to MAXIM INTEGRATED PRODUCTS MAX31865ATP RTD interface chip with serial output to PIC18F45J10 driving a DDM4 4 digit display.

If you were doing it at home without all of the kit I have available at work you should look around for stuff that already does what you need functionally and hack it about.

Our lab building does cleaver things with inlet and outlet air (the building is essentially sealed) We have 4 towers each containing 3 pairs of ducts carrying inlet air and exhaust. There is a chamber containing a very large thick disc constructed like a honeycomb. Think of fitting a large number of drinking straws into a section of pipe. The disk is arranged to have part of it's flat surface in the air path of the inlet air and another part in the exhaust. A motor driven spindle causes the disc to rotate slowly. So hot exhaust air heats part of the disc and is cooled before exiting the building and the now hot part transfers the heat to in inlet air as it rotate into that air stream. We get around 8 to 10 degrees temperature change in the inlet air on a good day which amounts to a big energy save.

regards Martin

Thread: Safety emergency stop switchs
19/01/2017 08:53:08

I have a emergency stop switch on the lathe (Newton Tesla drive) that is marginally helpful in as far as it's easier to hit than the normal stop switch in a panic and I cannot say I have ever used it. The Myford mill has a kick switch at floor level on the base which I use all the time to stop the machine as it saves reaching round the side to the starter. A floor mounted kick switch would be very handy on the Startrite drill press (something I've thought about but never implemented) as it's the only machine that you potentially have to stop when both your hands are in use. If you are drilling with one hand on the downfeed and the other holding the work (In a drill vise? ;0) ) and the drill stalls it's difficult to switch off without letting go of something. It has to be your right hand because the other is holding the work to stop it rotating and the switch is on the left side of the machine.

So in conclusion if you are starting from scratch you want a bump switch or kick switch on anything that ties your hands up. Fast access on anything that you walk away from when it's running and the most instant kill switch you can get on anything CNC.

regards Martin

Thread: Inverter with motor needed
18/01/2017 12:18:55

Generally I would ideally screen a motor cable at both ends so that the cable screen extends around the teminal housing on the motor and the motor casing. The object being to limit emissions from high current conductors.

For signal cables I generally want to screen one end only to obtain some shielding of my signals from external noise and to avoid ground loops and multiple earth points.

Generally for control gear using low impedance sensors (such as switches and pots) the main thing you are concerned about is EM radiation rather than noise immunity so it doesn't really matter too much unless the neighbors complain.

You have to remember that currents case magnetic fields and voltages cause electric fields so how you ground bond, ground reference and earth protect depends on what you are required to do and what you wish to achieve.

Have a go at building a PA sound system and earth everything at both ends and have a listen to the hum.

Connect your system according to the manufacturers instructions. If it works leave it alone. If you have problems like you cannot hear the test match on long wave or your tacho doesn't work properly then think about changing your arrangement.

regards Martin

Thread: Brake discs a suitable source of case iron
18/01/2017 09:33:53

As a small boy I built a "nuclear reactor" from an old metal tank with sash weights as control rods operated by string. If you lit a fire in the tank the whole thing warmed so was more realistic when sitting on the top 'controlling the thing" Somehow never go round to making a real one though. Happy days.

Martin

Thread: Left hand dies
17/01/2017 09:15:27

Tracy Tools probably

Thread: Inverter with motor needed
17/01/2017 09:14:36

Well put Andy Ash.

I would add the observation that whilst the topology of mains filters is generally symetrical Live to Earth and Neutral to Earth, the single phase supply is assymetric in as far as the neutral and earth potentials are usually within a volt or two. The 50Hz leakage component in the filter is predominantly on the Live side which is what causes the imbalance and as Andy has pointed out is additive when more filters (devices) are connected. Hook up enough filters and sooner or later you will exceed the trip current (30mA).

In our old building (Lab) we had no end of issue with earth current running through both the pipework and the reinforcing to the extent of many amps. I spent a week selectively earth strapping a water pipe in one of our electron microscope rooms in order to reduce the field generated by it. I built an active field cancelling unit in the end. We were aware that the main culprit were the many hundreds of computer mains filters each dumping current into the safety earth.

regards Martin

Thread: Slitting saws, How does one retain them on the arbour?
16/01/2017 12:22:21

My dad refers to Allen keys as church keys. His dad was a coffin maker amongst other things. They were used to fasten the lid down.

regards Martin

"more useless information"

Thread: Myford bearing spacer
16/01/2017 11:35:50

Why don't you ring Myfords and ask.

Martin

Thread: 'Re-purposing' old hand drills
16/01/2017 09:55:26

I've seen one used for engine control in a narrow boat. The control wheel is on the hatch cover bulkhead at the back of the boat and needs to control the engine which sits in the engine room between the cabin and the load space, some yards away on a traditional narrow boat, and requires bevel gearing to connect down to the engine. The components from a hand drill are just right for the job, cheap and easily available.

regards Martin

Thread: Myford ML7 countershaft hard rubber bushings source?
13/01/2017 13:56:37

Do you mean like this.

**LINK**

They are admittedly under the Super 7 Headstock section. I'm sure they will tell you if they are the same as the ML7 if you give them a bell. £3.60 each is quite cheap for a mortgage.

regards Martin

Thread: Myford bearing spacer
13/01/2017 11:50:36

With copper wire as a spacer it's probably just as well that the bearings were the wrong way round. The thrust load would be taken on the rear bearing rather than the front so it would have worked OK as a thrust bearing but the radial constraint would be potentially compromised. Essentially it would work as a single rather than a pair. Hate to think what would happen to the front bearing clearance if you were cutting away from the headstock or machining the a rear shoulder on an item.

regards Martin

Thread: bench drill clamping
12/01/2017 15:10:24

Candidate for Tip of the Week?

If you do happen to inadvertently drill a small hole in a machine table. Tap it 4 BA or something suitable, fit a grub screw and stamp OIL next to it.

regards Martin

Thread: Unusual adjustable spanner
12/01/2017 09:24:43

I do however have a pair of 14 inch adjustables one right handed and one left handed.

Martin

12/01/2017 09:22:41

It's OK for you modern lot but it wont fit square nuts..

;0)

Martin

Thread: Myford bearing spacer
12/01/2017 09:18:23

If you look in the manual on page 25 and 26 Figs 34 through 36 you can see that the bearings are fitted with the 'free face outwards. The spacer is Myford Part No A1991 Bearing Spacer Washer which I cannot find on Myfords online parts but eMail them and I am sure they can oblige. If you don't have a manual you can down load at

**LINK**

The system works like this.

The spacer washer allows the outer journals to be clamped together by the locking rings. The inners are preloaded by the split collar outboard of the sleeve gear on the end of the spindle acting through the sleeve gear and nipping the inner journals between it and the step on the spindle through the distance sleeve.

regards Martin

Thread: Alternative to PC based Cnc controllers
11/01/2017 16:22:05

I suggest you don't turn your computers off.

At least you will have plenty of cereal ports.

:0)

Thread: Aircraft General Discussion
11/01/2017 12:16:11

Were you now Carl. Fortunately I've forgiven you by now. Good to know someone cared. :0)

Our governments seem to have a habit of doing that to Nimrods. Beats me why the RAF or the contractors don't just park them up somewhere and pretend to have scrapped them. It's only a matter of time before someone decides it all been a great mistake. With CGI these days you could still give the journo's something to show on the news.

regards Martin

11/01/2017 11:34:18

Back in the day when I worked on AEW Nimrod, the Battle of Britain flight got relocated to Waddington whilst their home runway was being resurfaced. This was also just after the Vulcans had been withdrawn from Germany and decommissioned. We managed to wangle a tour round all the aircraft and went on board the Vulcan after crawling all over the Lanc. It struck me then how little separated the two aircraft in their technical feel. The Vulcan still had the electromechanical bomb computer and a lot of the internal structure and fittings were not widely different to the Lanc. Clearly their capability were far apart but in terms of the build not so much.

As an aside I was informed that they were a right b*****d to start if they had been left out in the rain. The switchgear was housed in a bay to the rear of the cockpit area and the seals were not to good. If they got wet everything would trip out repeatedly. Sort of could you keep the war going 'till we get there situation.

The other amusing story was every aircraft arrived back in the UK with nose full of german wine as the camera gear had been previously removed. Fine by the camp CO so long as he got a crate. Well they were unloading the plonk in one of the hangers and omitted to adjust the center of gravity by pumping fuel around. Half way through the operation the aircraft sat on its tail leaving the main hatch about twenty feet up in the sky!!! It only happened the once otherwise the booze cruises would have been stopped.

regards Martin

Thread: Cast Steel, Nickel Steel, Phos Bronze?
06/01/2017 10:59:03

When built my Quorn the rotating base material was cast steel and it machined really nicely. Sort of cast iron without the dust. I assume it was just a low carbon steel that had been cast rather than drawn so no skin stresses.

regards Martin

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