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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: Voltage drop
24/02/2017 15:09:37

mmm. but the propagation velocity depends on the dielectric constant so it's slower for 2.5mm twin and earth.

Martin

24/02/2017 14:50:28

Now if if was copper pipe a few years back there would have been so many pinholes in the mile that you really would not have got any water out of the end.

Martin

24/02/2017 14:33:20
Posted by Muzzer on 24/02/2017 13:09:40:

Ian - unlikely unless you have a VERY long cable. To get any appreciable AC effect you'd need to get somewhere close to the wavelength at 50Hz. Even a 1/4 wavelength at 50Hz would be about 12,000 km. The inductance will be pretty low, as the conductors are close together. Not quite interwound but close all the same.

Murray

There are two effects relating to AC apart from the IR losses.

Firstly the cables radiate and lose energy. We have all heard the mains hum on radio 4.

Secondly for very long cable you can get reflections from the load(s) which set up standing waves. Site your tap off point at a node and you see zero voltage. The cable length does have to be extremely long as in many thousands of kilometers and at does depend on the termination. (End load).

I suspect that the original poster is remembering the schoolboy stories of power lines in Russia. This scenario is unlikely as you would no doubt build your power stations a lot closer to where you need the power.

Thread: Securing threaded backplate
24/02/2017 12:36:23

Yes Jason but if you bolt the stool to the floor it is unconditionally stable.

regards Martin

PS waiting for my board to etch

24/02/2017 12:33:14

Hi Bill

You are perfectly correct re the griptru as the tapered cone system only pushes and you need to pull as well to do two at the same time. The same applies to tripods. Where 3 bidirectional threaded adjustments are concerned it is however possible to obtain orthogonal adjustment planes by contra-rotation of two screws for one plane and the 3rd for the other.

Setting tripods level over a pin always baffled me. I could do it no problem but could never quite figure why it worked. You basically went side to side with one leg for one plane and up and down for the other to get the head level. Then adjusted each leg to move in three planes to get vertically over the pin. The top would no longer be level but usually withing the fine adustement of the tribracket mount for the theodolite.

regards Martin

24/02/2017 12:08:29

I know you often don't get a choice on how many screws hold a chuck but when the Grip-Tru type adjustable backplate is made why do they insist on still using 3 screws for adjustment.

Adjust three screws at 120 degrees is a right pain working out what is going to move what way.

Why don't they use 4 and mimic a 4 jaw chuck where you work in two sets of 2 jaws for adjustment.

Maybe it's because with 4 adjusters on a 3 jaw chuck you cannot fit the adjusting screws in without running into the pinion holes. Even with radial screw adustment rather than tapers you still wind up having to position your adustement screws within 15 degrees on the chuck jaw centres on 2 of the . I suppose you could make the chuck longer and duck underneath the pinion holes but that would increase overhang.

Comments please.

regards Martin

24/02/2017 10:48:34
Posted by JasonB on 24/02/2017 10:30:15:

I'm inclined t

oooh you don't want to be inclined it's all supposed to be level!

:0)

Martin

24/02/2017 09:29:07

Usually when adjusting a 3 screw setup you use 2 keys in 2 screws turned in equal but opposite directions. This rotates the item along an axis bisecting the screws and running through the 3rd. Once that plane is correct you just adjust the 3rd screw and you are there. Simples. Standard leveling technique for tribrackets in serveying.

regards Martin

Thread: Clutter in lathe swarf tray
23/02/2017 14:27:42

Well that's certainly one good idea (lift out tray). At least it would contain what does end up there. I have got some degree of organisation going on. I have a pierced shelf next to the lathe that holds drill chucks, centres and taper tooling vertical. A QC tool holder rack and hook board that takes care of all the chuck keys, spanners and stuff. I think my biggest problem is getting myself to slow down. Case of more haste less speed I think. I am convinced that being tidy as you go is quicker than waiting until you have to tidy up but its hard work when you are trying to finish the bit you are on before it's time to go in. Still retirement looms and perhaps I shall be a little more relaxed.

regards Martin

23/02/2017 12:41:58

Prompted by the posting on the industrial stand drawer I got to thinking about my seeming inability to stop myself filling the swarf tray on my lathe up with what ever I last had in my hand, calipers, spanner QC toll holder etc. Does everyone else do this or am I the only one. If you don't how have you trained yourself out of it? I already have a rack for toolholders but they still wind up in the tray 9 times out of 10. I know ultimately it's self discipline but there must be ways to encourage good practice. Maybe you think it doesn't matter but I know it puts me off cleaning up regularly if I have to relocate 20 items before I can start swarf removal. Having just changed my lathe I am keen to acquire some better habits.

regards Martin

Thread: Evening Star
22/02/2017 14:36:11

There is also

**LINK**

if you are interested.

regards Martin

Thread: Hi everyone !
22/02/2017 12:11:49

Here is a brief cost benifit analysis of the Super7. It's is based on my workshop needs which are small scale steam (5" guage and moderate stationary engines) and clocks and workshop tooling. I have a vertical mill.

1. Ease of headstock dividing.

2. Boring table for clock wheel cutting, milling and obviously between centres boring.

3. Size.

4. Full support for spares (including second hand)

5. Amount of tooling based on the Myford

6. Precision when in good condition.

7. Open to self improvements (Slide locks, better micrometer dials, saddle stops etc)

Drawbacks

1. Can be pricey although my 1st one was £700 and I have just replaced it with a works reconditioned machine with power cross feed and gearbox for just over £3000.

2. Small bore up the spout. Spindle only passes 5/8" for the small bore.

3. If you want to build big stuff (4" traction engines etc) it's too small.

4. Metal removal rate is not huge. (well it's a toolroom lathe)

regards Martin

PS I'm sure others could add to the list.

22/02/2017 11:33:50

What are you planning on making mostly and do you intend to get a mill?

regards Martin

Thread: Evening Star
21/02/2017 12:29:26

So that puts me in the group that don't agree with him then.

regards Martin

21/02/2017 10:41:14

Astronomical stars.

Martin

Thread: Cheap chucks from ebay.
21/02/2017 09:30:43

Sound like a plan to me Nick although new Pratt chucks would be outside the topic of the tread.

Martin

Thread: Evening Star
21/02/2017 09:15:25

You absolutely do not get green stars.

Martin

21/02/2017 08:43:12

There are 2 planets in the Western sky in the evening at the moment. Venus and Mars. Venus will set at 21.16 and Mars at 21.41 approximately. Mars is much redder than Venus. Generally if an object is bright and on the ecliptic (path of the moon) it's a planet. If its moving it's an aircraft or a satellite. Momentary bright streaks are meteors. Jupiter rises in the East at around 22.00 and is in the SE by about 6.00 the next morning.

regards Martin

Thread: Cheap chucks from ebay.
20/02/2017 15:43:12

So my conclusion is if you want a cheap chuck go for an economy standard precision new one rather than a high end old one. You are unlikely to get the low run out that the high end one once had and the jaws will have seen some use to boot. With then new one at least the jaws should close parallel. I know you can always regrind but that will not put the wear back on the tenons and new jaws are expensive.

That said I pensioned off my old griptru by buying it a set of soft jaws. In addition I have a 2 independent four jaws, a self centering four jaw an a Super Precision Pratt Burnerd for Sundays.

regards Martin

20/02/2017 14:56:53

Are we forgetting the primary purpose of a chuck is to grip the material firmly so it does not either slip or wobble about (by that I mean move rather than stay fixed albeit off centre). Worn jaws do have a tendency to do both which defeats your ability to turn parallel or round, produce a good finish or tap from the tailstock without the work turning.

Wear on the scroll will matter much less than wear in the jaws.

That's not saying you cannot get a bargain now and again.

regards Martin

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