Edison dynamo

[Steamchick]

And I thought the Romans had invented city plumbing.... but I do remember that Ephesus and Siraceus had ancient plumbing, so I wasn't paying attention properly....
On Internal threads -In blind holes: If the lathe will run backwards, you can make the tooling "up-side down", and working on the back surface of the hole, start at the bottom of the hole and work the tool out (as if un-screwing the to from the job). This is contrary to the loading of the taper slides on the lathe, but if the slides have correctly set gib-strips then the slack will be negligible and you'll find it will work if not overloaded. Also, when cutting threads, consider cut in on one face only. Set the top cross-slide around 60 degrees, so the tool progresses along one face of the thread and only cuts the second face - make this the leading face for the direction of feed. Then the tool can have correct relief of cutting angles, and not bind or chatter when working hard or difficult materials. The set-up takes time but the reward is the finished job. Enjoy!

 

[Steamchick]

Sorry, got my head screwed-on the wrong way today. If working at the front and with lathe running backwards, the tool needs to be upside-down, or if working on the back face needs to be a back-to-front (opposite hand) boring bar. But you'll work it out anyway, I'm sure!

 

[Richard Hed]

Yes quite so he reduced Maxwell's correct but rather long winded ideas to something more manageable among his other many accomplishments including research into Characteristic Impedance leading to the development (and patenting) of the coaxial cable.

I think Europeans and the British in particular have a tendancy towards science as an end in itself whereas Americans are more open to the commercial and practical applications of ideas, which may explain why many European scientists tend to be less well known.

Best Regards Mark

Yes, I thimk Heaviside is responsible for some of the important work on impedance.

 

[Richard Hed]

Sorry, got my head screwed-on the wrong way today. If working at the front and with lathe running backwards, the tool needs to be upside-down, or if working on the back face needs to be a back-to-front (opposite hand) boring bar. But you'll work it out anyway, I'm sure!

That's one of the problems with a crappy enco==yes, it has a reverse switch, but I wouldn't call it "reverse", that is, what we would expect if we wanted to make LH threads. I can't slow it down to a manageable speed to turn off the switch, as I can't disengage the thread nut--it will lose it's place no matter what I try--it is a total peice of (Be nice) BLEEP. So my solution was to make a wheel to work the spindle by hand. It works just fine, have to back out the cutter by hand but it is very slow process.

 

[Steamchick]

Hi Mark, on Turbines... I have been considering shaft speeds and loads of various options for driving engines.... directly, rather than with gearboxes. I have a Stuart and Turner Sun engine - good for 20 00pm - but needs a reliable oiling system to counter crank journal wear. I made it 20 years ago for a launch, but it was just too heavy for the hull. The boiler is quite big.... so I changed to the smaller Star engine. But as I have not found a suitable generator for 1000 - 2000rpm, (maybe I should make an Edison generator?), my mind has wandered to thoughts of a turbine for 10,000 rpm.... but maybe that's too slow for a Tesla model turbine... I have seen turbines for model sizes going 10 times faster... and need special bearings and lubrication to cope! Not my game. But as I have a field coil from a burnt-out drill, maybe I could make a rotating permanent magnet armature and use it at "Model Steam engine speed" as a 2-pole alternator? Or maybe just converting my good brush motor to a dynamo with regulated field is the simple option? Choices! Back to the calculator to match desires and expectations....

 

[Richard Hed]

Ah James Clerk Maxwell (1831 - 1879) James Clerk Maxwell - Wikipedia another misunderstood and under appreciated genius.

(oops I can feel another rant coming on so back to dynamos)

Yes rotating machine design whilst the basic principles are simple can get very complex, very quickly. So before you go completely potty and start quoting Maxwell's Equations to your therapist I think I may have a cheap and almost ready made solution,

What about the armature from a cordless drill they are D.C. and rated for about the right voltage and current you need.
They are very rugged in fact almost indestructible. (they need to be in a machine that has to withstand regular overloads and even complete stalls).
The best bit is they are likely to be cheap or even free as people often chuck out usable cordless drills because the battery or charger has died or is too expensive to replace. The field assembly and brushgear from the existing miniature Edison that quite a few have built should match quite nicely with one of these.

Meanwhile it will be interesting to see how your Duplex "whizzy magnet" machine develops keep us posted on how it's going.

Best Regards Mark

I'll have to remember to tell my therapist about Heaviside and Maxwell, Thanx for the tip. LOL

 

[Steamchick]

The brush motor in question as a total resistance of 98ohms, (38 ohm armature). So at 240V it could draw 2.4A. But it only takes 0.75 at 50Hz. - obviously due to the added impedance from the inductance. So should I expect the same motor performance if I ran this motor at 75 DC? - Or would the impedance of the Armature - switching coils at 183Hz. - reduce the current and performance? I can imagine there will be a DC portion running in the field coils, with a ripple from the Armature switching coils. So perhaps I need a text book on DC motor design, now? Or am I thinking too hard?

 

[skyline1]

The reason your motor draws less current than it's D.C. resistance would suggest is due to back EMF.
At a standstill the supply only "sees" the D.C. resistance plus a little due to the inductance of the windings so it WILL draw about 2.4 Amps but as the speed increases it will produce Back EMF according to Lenz's law Lenz's law - Wikipedia so that at running speed it only draws 0.75 amps

The ratio of starting current to running current is about 3.2:1 which is probably about right for this motor although some machines can have a starting current of 10 times their running current or more

Starting Current is a big problem on large machines and is the reason for Star Delta and wound rotor resistance starting. More recently electronic soft starts are used.

I think you may be concentrating on winding impedance and not considering the Back E.M.F. which has a far greater effect

If you are thinking of going the turbine route my little DeLaval's run at about 30,,000 R.P.M. and produce about 4 Watts at 12 Volts Ish using small permag motors like you get in electric toys I have quite a collection of them of various shapes and sizes (Somewhere amongst my other junk).

This Is quite a modest speed by turbine standards. The model jet chaps are running at 80,000 R.P.M plus. But even at this speed they do eat bearings I have to change them fairly regularly. (about every 50 Hours or so) I might change them for Ceramic ones at some later date they are available in these small sizes but they are very expensive.

If you decide to build a little permag alternator I suggest you go for a 4 pole rather than a 2 Pole as this will keep the speed requirement down synchronous speed for a 4 pole machine is 1500 R.P.M. at 50Hz as against 3000 R.P.M. for a 2 pole.

Decisions, Decisions It's a real Pandoras Box this mini generator caper as I'm sure you are finding out. Experimentation is the name of the game as much as science in small scale as effects that can be largely ignored in larger scales have a much greater effect the smaller you go.


Best Regards Mark

 

[Steamchick]

Thanks Mark. More useful advice there!

 

[L98fiero]

I can't disengage the thread nut--it will lose it's place no matter what I try

If that's the case, it may have a metric leadscrew and then, you can't disengage the halfnuts.

 

[gunner312]

It's not necesarily true, you can disengage the half nuts when threading metric with imperial screws. it's all in the method.
I do it all the time and don't find it a problem. If you have a metric screw, then threading metric is normal operation. What I think is the problem is that you must engage on the even numbers if the pitch is an even number (2,4,6,12,24, etc) and on odd numbers (3,5,7,13,etc) when the pitch is an odd number. When the pitch is an even number, you should be able to engage on any number of the thread indicator but some lathes I have found will work better when you engage on the even numbers for an even pitch number and odd for odd etc. also you must change the drive gears to compensate for the difference between inch (imperial) and metric lead screws. If you don't do this then even engaging on the correct numbers won't work.

If that's the case, it may have a metric leadscrew and then, you can't disengage the halfnuts.

 

[Steamchick]

If you decide to build a little permag alternator I suggest you go for a 4 pole rather than a 2 Pole as this will keep the speed requirement down synchronous speed for a 4 pole machine is 1500 R.P.M. at 50Hz as against 3000 R.P.M. for a 2 pole.
Best Regards Mark
[/QUOTE]
Hi Mark, I am thinking of driving the generator for 12V or 24V DC - so would be doing simple rectification of the AC from a spinning magnet alternator - then manage the DC voltage with a Buck controller - and just lighting some bulbs or LEDs. As I have a few Boilers and Steam engines, I am not even sure which combination I shall match to a generator - when I get that elusive Round Tuit!

 

[L98fiero]

It's not necesarily true, you can disengage the half nuts when threading metric with imperial screws. it's all in the method.
I do it all the time and don't find it a problem. If you have a metric screw, then threading metric is normal operation. What I think is the problem is that you must engage on the even numbers if the pitch is an even number (2,4,6,12,24, etc) and on odd numbers (3,5,7,13,etc) when the pitch is an odd number. When the pitch is an even number, you should be able to engage on any number of the thread indicator but some lathes I have found will work better when you engage on the even numbers for an even pitch number and odd for odd etc. also you must change the drive gears to compensate for the difference between inch (imperial) and metric lead screws. If you don't do this then even engaging on the correct numbers won't work.

I guess I should have been more specific.
If you are threading inch threads on a metric lathe you can't usually disengage the halfnuts and pick up the threads with a thread dial or vise versa. You can do it but not easily, there is a good explanation of why in the Martin Cleeve book Screwcutting in the Lathe, pp 73, 79. One of the examples he uses suggests that if you wanted to cut a 1.75 mm pitch screw on a lathe with an 8 tpi leadscrew with a 50/127 translation ratio, if you disengage the halfnuts, you'd have to wait until the leadscrew turned 874 times before you could re-engage the halfnuts. He also says that geared thread dials for metric threads on inch machines is possible as well but not particularly useful and I've never seen a setup like that in 45+ years.
Is it possible, yes, practical, no in most cases.

 

[Richard Hed]

The reason your motor draws less current than it's D.C. resistance would suggest is due to back EMF.
At a standstill the supply only "sees" the D.C. resistance plus a little due to the inductance of the windings so it WILL draw about 2.4 Amps but as the speed increases it will produce Back EMF according to Lenz's law Lenz's law - Wikipedia so that at running speed it only draws 0.75 amps

The ratio of starting current to running current is about 3.2:1 which is probably about right for this motor although some machines can have a starting current of 10 times their running current or more

Starting Current is a big problem on large machines and is the reason for Star Delta and wound rotor resistance starting. More recently electronic soft starts are used.

I think you may be concentrating on winding impedance and not considering the Back E.M.F. which has a far greater effect

If you are thinking of going the turbine route my little DeLaval's run at about 30,,000 R.P.M. and produce about 4 Watts at 12 Volts Ish using small permag motors like you get in electric toys I have quite a collection of them of various shapes and sizes (Somewhere amongst my other junk).

This Is quite a modest speed by turbine standards. The model jet chaps are running at 80,000 R.P.M plus. But even at this speed they do eat bearings I have to change them fairly regularly. (about every 50 Hours or so) I might change them for Ceramic ones at some later date they are available in these small sizes but they are very expensive.

If you decide to build a little permag alternator I suggest you go for a 4 pole rather than a 2 Pole as this will keep the speed requirement down synchronous speed for a 4 pole machine is 1500 R.P.M. at 50Hz as against 3000 R.P.M. for a 2 pole.

Decisions, Decisions It's a real Pandoras Box this mini generator caper as I'm sure you are finding out. Experimentation is the name of the game as much as science in small scale as effects that can be largely ignored in larger scales have a much greater effect the smaller you go.


Best Regards Mark

I would very much like to know more about those ceramic bearings you are talking about. Have you ever used them for anything?

 

[Richard Hed]

If that's the case, it may have a metric leadscrew and then, you can't disengage the halfnuts.

I'm sure that for imperial threads I am doing something wrong, but I don't know what it is. I engage the half-nut properly but the threads walk all over the place anyway. For internal threads it is impossible so now I just do the turning by hand and leave the half-nut engaged.

 

[goldstar31]

Richard

Have you checked the leadscrew, please? My Myford is 8 TPI whereas my Sieg is 3mm but 3 milli is nearly 1/8th== but NOT.

If you have a worn- well anything or sloppy fits to the gearing???????------or WORSE if your lathe has all of these, time to buy something better

always remember that Martin Cleeve( for those who have read the book) that he made his micrometers using his Myford leadscrew

Points to ponder?

Norman

 

[Richard Hed]

Richard

Have you checked the leadscrew, please? My Myford is 8 TPI whereas my Sieg is 3mm but 3 milli is nearly 1/8th== but NOT.

If you have a worn- well anything or sloppy fits to the gearing???????------or WORSE if your lathe has all of these, time to buy something better

always remember that Martin Cleeve( for those who have read the book) that he made his micrometers using his Myford leadscrew

Points to ponder?

Norman

This lead screw is 16tpi, screwy, eh? I'll double check however, now that you mention it to see if it is EXACTLY 16 tpi or NEARLY

 

[goldstar31]

I look forward to your further observations

16 turns= 1 or 2 inches travel

 

[Richard Hed]

I look forward to your further observations

16 turns= 1 or 2 inches travel

16 tpi = 1 inch. Altho' I have had this lathe for about 10 years, I have used it very little, as I usually live in the Philippines and haven't had much time to play with it. But recently, I have been turning parts for toy steam engines. I am also designing some not-toy engines. The gears are fine, despite some of them being plastic. I want to cut some new gears before the plastic ones self destruct. My daughter and I are working on building a small foundry to cast parts for various projects. I will needs to make some mold blanks. Been eyeing those 3D printers, am wondering if my local community college has a 3D printer. It is much cheaper to "go to school" to use the tools they have than buy one myself--That's something some of you might consider doing if'n you caint afford tools. Problem is, this weeks (month's, year's decade's) virus is stopping a lot of stuff including the schools. (Newton had to quit school because of the plague!)

Well, to pay the fees is very little as one pays $5 per unit hour of classroom time plus a bit for general fees at my age (anyone over 60 in my Soviet of Washington). I planned on going in April of this year (2020) but the school is shut for the virus.

 

[goldstar31]

Well 16 factorises as well as 8TPI and there should be no difficulty in getting a suitable gear train to cut gears.

My Myford has a set of gears happily tied up in a box to do most things but a tad expensive perhaps whilst the Sieg seems equally at home without!

I, at almost 90 am tied down, sensibly having already disbursed money as the remaining share holder in Mum and Dad's Bank Limited and at the suggestion of my friends have spent a little on my self- for a change.

Meantime, I wish you well in your pursuits

Norman