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Member postings for WALLACE

Here is a list of all the postings WALLACE has made in our forums. Click on a thread name to jump to the thread.

Thread: Using engine flush on a lathe headstock.
04/10/2014 06:36:40
My L5a headstock gearbox is painted red on the inside -so I wouldn't use anything that might attack paint.


W.
02/10/2014 20:32:46
Paraffin, rags and compressed air...if it's L5 series, the headstock gear cover comes off easily enough but you will need a thin smear of sealant around it otherwise it leaks !
I also left a magnet in there to pick up any metal debris - one of these days I'll fish it out and frighten myself. ...


W.
02/10/2014 16:27:50
How about paraffin ?

It's what I used to clean out my L5a.....


W.
Thread: LEDs ... The Good, The Bad, and The Ugly
29/09/2014 18:11:33
Hi Les.

I know the type you mean - they use a ferrite core in the transformer - the ones I'm wary of are the 'choppers' which I don't think are electrically isolated from the mains. The choke or inductor on the output is purely for smoothing.

Is there a different name for them ?--I always assumed they were also 'split mode' but could well be ignorance on my part !In fact, I don't actually know why they are called 'split mode' - can anyone enlighten me ?

Michael - I'll put a scope across them and post the results at the weekend - should be easy to do as I extended the original wiring so will be dead easy to hang a probe across. I'll try and do ac as well as dc.



W.


29/09/2014 13:16:08
Hi Les.

I personally prefer to have a magnetic field between my fingers and the mains !



W.
29/09/2014 13:04:29
Hi Michael.

I will do a picture at the weekend - from memory, 4 diodes ( bridge rectifier ), 8 leg chip, a couple of resistors, small inductor and an electrolytic capacitor. ...47uf or thereabouts rings a bell. And in that order from the input to output connections.

The circuit board for the higher power 3 led one had a couple more components but still had the diodes, chip, inductor and capacitor so both are presumably some kind of high frequency chopper regulator.

That's why I'm assuming they won't be over fussy on input voltage - obviously within reason !

But I have only run them on dc so far.

The red led lights merely had a single package rectifier and one large resistor - nothing fancy at all.




W.
29/09/2014 12:19:17
Hi Michael.

I wouldn't imagine they'd flicker as the internal capacitor must smooth the ripple.

I will put a scope etc across them but not until the weekend - I'm in London, lathe etc is at Dads house !

I would personally go for a basic 12 volt transformer for workshop lighting - I don't altogether trust the 'electronic' ones as they don't provide isolation from the mains. I also think rectification etc wouldn't be necessary - raw 12v ac would be fine.




W.
Thread: Model Engineers' Workshop Open Forum
29/09/2014 11:05:40
Will rotten tomatoes be available to purchase at the exhibition or should we be expected to bring our own ?!


W.
Thread: LEDs ... The Good, The Bad, and The Ugly
29/09/2014 11:02:42
Hi Les.

Presumably, they're designed to be able to run on ac not just because the sockets aren't polarised but because some fittings just rely on a 'old fashioned' transformer to get the 12v from the mains. I imagine the 12v from an 'electronic' transformer is a bit rough - it would be interesting to hang a 'scope across one.

I'm probably going to try an led bulb in the lovo light I have on the lathe - as when I replaced the stainless storage tin I was using as a shade with something a bit more in keeping, the halogen MR16 bulb I had fitted came out with only one pin intact !

I'll measure the lovo light voltage out of curiosity but I'll probably suck it and see and not bother regulating it - it will be interesting to see how long it lasts. But I may miss warming up my hands on the shade on cold winter evenings in the garage with the cooler running led bulb fitted !

The other point possibly of interest with led bulbs is the viewing angle - I'm going to fit two on the front of the bike, a 61 led wide beam of around 140 degrees and a brighter switchable more concentrated one of around 30 degrees - this only has 3 leds which actually use the aluminium 'reflector'as a heat sink - something new to me on an led !


W.
29/09/2014 00:11:26
I recently bought some cheap and cheerful 12 volt MR16 led bulbs to turn into bike lights from ebay - incidently all UK suppliers - and deliberately broke the glass away to free up the circuit board with the leds mounted on them.

The red lights had a small bridge rectifier plus a current limiting resistor on the boards, the two white ones were a lot more sophisticated with a separate small pcb with not only rectifiers but a small surface mounted chip, various resistors plus an electrolytic capacitor and inductor.

So they must be ok to run on ac - and I would imagine the white ones would be fine with a few volts either way as well. They weren't dimable ones which presumably won't vary much in brightness with input voltage - I must admit I only ran them on 12v dc.

An unregulated nominal 12v ac supply should therefore fine ..IMHO !

W.



W.
Thread: Silver soldering invar ?
26/09/2014 14:00:28
One for the clockmakers...


Can invar be silver soldered without harming it's low expansion properties ?


Thanks.


W.

Thread: Really Silly Question - rpm facing off large diameters
17/09/2014 12:14:41
I would have thought ...that the feed per rev needs to be constant otherwise you'll end up with different surface finishes..

Facing could be seen as ploughing a long spiral into the surface ( well, it is with my tool grinding. .) so I would assume the spacing of the spiral needs to be constant ...which means the same feed per revolution..????


W.
Thread: Favourite Engineering quotes.
17/09/2014 09:52:56
'To err is human, to forgive is by design'.






W.
Thread: Really Silly Question - rpm facing off large diameters
17/09/2014 09:46:15
Ok..I'm dense....


Why would the feed rate have to be increased ? Wouldn't just an increase in rpm to keep the cutting speed constant do the trick ??

I vaguely remember somewhere an engraving of a very early lathe using a complicated system of cone shaped pulleys to try and do this - maybe in the series of articles about the history of machine tools that ran years ago in MEW.



W.
Thread: Help please on identifying something
02/09/2014 23:42:29
I reckon it's from a Harrison L5 or 5A - it looks very familiar !

If you keep an eye on the saddle as it approaches the stop, it's easy to drop the auto feed lever while keeping your left hand on the saddle hand wheel to just take up the final 20 thou or so before it hits the stop - assuming you're not using high roughing feeds.

Best to try and keep the saddle moving without stopping otherwise you get a slight mark on the work piece - well, at least I do !



W.



W.
Thread: Anti Corrosion for Electromechanical Things....
10/07/2014 09:01:35
Thanks for the replies - it's going to be difficult to enclose it in a bag or similar - the video recorder is large ! - with the monitor bridge on top, it's the size of a wardrobe and weighs about 600 pounds ....

Hence the thought of something to spray on and remove when I eventually get around to cleaning, and hopefully, getting it working.



W.


09/07/2014 13:06:55
Amy thoughts or ideas for inhibiting corrosion on something with both electronic circuit boards and big electric motors, moving parts etc?

It's stored in a container at the moment and I don't think the usual hydraulic oil would be suitable!

WD40 perhaps or is there something better - and that could be removed reasonably easily from the electronic parts ?

Thanks


W.


In case anyone's interested, it's an Ampex AVR2 2" video recorder. ...
Thread: stuck cylinders
09/07/2014 08:55:37
No idea if this would work on a small engine, but I recall a tv programme where seized pistons in a car engine were freed by liberal use of near 'boiling oil' poured into the bores. Possibly a combination of heat, lubrication and the heated thinner oil penetrating more easy.

W.
Thread: Scams on ebay
08/07/2014 22:41:00
It's the postage which shows it's a scam. Anything that big would usually say something about a pallet or fork lift truck being available for the buyer to collect - or if a dealer, a rate per mile for delivery.


Someone's going to be disappointed ......


W.
08/07/2014 22:12:01
I love that one - postage is free second class delivery !

The postman is going to struggle getting that one into his bag....


W.
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