Stringer EW lathe

Alan [and everyone interested]

You have hit upon one very important point, that merits further discussion.

For the EW fine feed ... Do you want it "Independent" or "Synchronised" ?

The Exactus is Synchronised, as is any geared drive; but there have been several successful designs for Independent fine feeds.

MichaelG.

If we opt for Synchronised, it could eventually be developed into an "Electronic Leadscrew" for Screwcutting. ... But let's walk before we try running.

Hello Neil,
Sorry for answering your message so late.

At 2012.08.22 you wrote:
You also need to pick up 'Ned' and 'ETW' and "Westbury' and probably other search terms as well. - a man
with one pen-name for each of his (many) areas of interest.

The first time I read this message I thought (because of my poor domain of your language) that you were making a little jock.
A second read told me that perhaps it was a suggestion rather than a jock.
A third reading make me be sure it was really a suggestion.
By this interpretation, I am sorry.

Now answering your suggestion:
The query I made had the sole criterion of ' EW ' in the title. Meaning that doesn't matter who is the author.
If I use OR as the logical operator with ' EW ' as criterion also in the notes I found one more article title "Bottled gas" and with note "Stuart No 4 and Sirius engines made on a 2 1/2' EW lathe".

Best regards
Dias Costa

Hello Alan Smith 6

Can this reversal be controlled manually? This is to do away with the complication of micro switches or their modern equivalent.
In my experience, a stepper motor stops rotation (not even a step more...) as soon as the power is cut.

Best regards
Dias Costa

Hello,

In my opinion it's a pity if this project stops at fine feeding a lathe.
At least it should keep the door open to go further to screw cutting and also as Mr. IanT suggested to control a rotating table .
There's a thread **LINK** and a product **LINK** called ELS. Information on both links may be a source of usable knowledge for this project.

Has anyone considered the possibility of using Raspberry pi or Arduino as the source of logic signal to the driver?
They are cheap (Raspberry pi: Total inc VAT and shipping = £31.86 , Arduino: £46 ) both are programable, the first is a highly meritory initiative, etc.

Obtained information for Raspbery pi price from here **LINLK**
Obtained information for Arduino price from here **LINK**

Usual disclaimer.

Best regards
Dias Costa

Hello Allan 6 & Ewers and others,
 

Unfortunately I don't know the EW lathe, so my appreciation of relative dimensions is poor.

The reference to the ELS product has only, as I said, the purpose of, eventualy, taking them as a source of information. Not to be followed as a model, and, I must stress, specialy not in size.

Adding some information to my previous message:
Both the Raspberry and Arduino are 105mm x 55mm . A little more in length than the size of a credit card.

For a simpler solution, not programable by itself, there is a simpler driver from Quasar electronics (**LINK**) that I use in my milling to drive the X axis table. Apparently the available board is a more recent version than mine.

It's dimensions are 80mm x 50mm x 22mm and you can directly control the voltage, the rotation direction and stop/start and its price is aroung £25.
It is called “3179 – Standalone / computer controlled unipolar stepper motor driver”.
The use of this driver keeps the door open for a more evolved and powerful version, eventualy usable for screwcutting or dividing, since it accepts external commands.

Best regards
Dias Costa

Edited By dcosta on 29/08/2012 15:00:31

Alan,

Please forgive me if I appear to be preaching … that is certainly not my intention, but I do have an important point to make:

You say: "… a twiddle of a knob will give a slower or faster feed as required."

Now, "twiddle of a knob" is a very Analog phrase, and I think we should be thinking exclusively Digital. … It is possible to mix the two, but it tends to be complicated and/or expensive.

The A3983, as implemented in the JAFmotion MicroStep, does everything that we NEED to emulate the Exactus Ratchet System [and more].

Straight out of the box, it offers:

• Drive Current of 1.2A per phase [which should be adequate]
• Switchable Forward/Reverse [whilst the system is running]
• Switchable Step-Mode [whilst the system is running]
• Step-Modes equivalent to 1/1, 1/2, 1/4, 1/8 Gearing
• Virtually instantaneous Stop

The wiring is extremely simple and we do not need an additional computer to drive it.

Hope that makes sense

I will answer your other points in my next posting.

MichaelG.

Edited By Michael Gilligan on 29/08/2012 17:53:40

Allan Smith 6 & Ewers and others,

I looked at your milling table drive photos and there is probably some of the answers to our problem contained in them, although it does not synchronise with the spindle as in our case.
That's why I referred in a previous message the necessity/convenience of some more, simple or complex, electronics to provide pulses (1, 2, 3, n pulses by a revolution of the spindle).

Can you tell us what stepper motor you used and the available torque?
For motorizing the X axis of my milling BF20 I made some experiments with stepper motors, first from salvage and then from Arc Euro Trade (AET).
Soon I put the salvaged motors aside because for most of them there was not any information. Also, fearing the risk of not finding an equal motor in case of failure, made me chose AET motors. Their price is acceptable for my purpose.

Firstly I experimented a motor from AET ref. 160-010-00200 having the torque of 180Ncm. Its power was perfectly enough to drive the BF20 table. However after awhile I experimented with a more powerful motor 220Ncm, also from AET (ref. 160-010-0400) having the torque of 220Ncm.
There's another stepper motor less powerful also from AET (160-010-00100) having the torque of 36Ncm.
Just as an opinion, I think that the stepper motor having 180Ncm torque is enough and a good acquisition

is it easy to change direction and is the potentiometer used to increase the voltage and therefore the speed of the motor?
Yes it is. In one of the boards I have (I bought two), a friend of mine, after removing the original onboard potentiometer, applied an external one with two cables soldered on the board, and also applied a small resistance just to allow me to control the voltage remotely. Problem is, the potentiometer and resistance used were the ones I had at hand, not the most adequate. So the outside voltage control never was tested as it should and I am using now a new driver.
The change of direction may be done whilst the system is running.

What is the power source is it a standard item that you can buy?
I use two independent power sources. One for the logic (the board) and other for the motor.
The first is a mobile telephone charger.
The other is an 12Volt 3Amper common power source,

No disrespect to you Dias, your layout is typical of an amateur such as myself with the components exposed and the control of the motor done directly from the board.
Yes you are right. I'm always expecting to ameliorate the system but it never happens. And I already had problems caused by swarf. Had luck the board is robust and resisted to the swarf short circuiting some components.

Is it possible to have the controls remote from the board so as to make the whole thing more tidy and presentable.
Yes it is. You only need to de-solder the direction switch and the potentiometer and replace both by cables connected to the appropriate components.
There is one more switch to chose from inboard control or external control you must put in INT position.
To stop and start I use this switch but I think the best and correct way is to cut the power for the logic and for the motor simultaneously.

Hope I answered all questions you asked and my answers arte of some utility.

Best regards
Dias Costa

Edited By dcosta on 29/08/2012 18:17:27

.

Sorry Alan ... I have enough "challenges" on my list already; and I thought we had decided that this had the makings of a collaborative project.

You say [above] ... "One thing that I`ve picked up on is your question where you ask, why do I want to be able to change the rate of feed when it is not in the Exactus design.

From this I imagine that you are perhaps not so experienced in lathework. The Exactus design does not allow a change of feed unless the feed ratchet gear is changed! I supposed that with the stepper motor this could be done whilst the feed is in operation."

.

Although not professionally trained, I do have plenty of experience in Lathework, thank you ... and I am perfectly aware that a range of feed rates is desirable. ... What I was trying to find out was whether this was on the "Must" list, or the "Nice to have" list. ... You are, after all, starting from a baseline of the Exactus design, but you stated: "I would expect that this rate of feed to be immediately adjustable to suit the type of material being machined."

I have offered a suggestion ... but will now hand it over to the forum

[quote] ... let`s see how you actually propose to carry out this design together with the switchgear and everything else to achieve the proposals that I have laid down without any jargon or acronyms and let`s see some sketches. Please accept this challenge ... [/quote]

Quite simply, Alan; I do not "propose to carry out this design < etc. >" ... I do not have an EW, and have no particular interest in the machine-specific detailing. ... so it's over to you chaps.

I genuinely wish you every success.

MichaelG.

Edited By Michael Gilligan on 29/08/2012 21:51:37

Out of a genuine desire to help others where I can!

... I played no bluff ... I simply made a suggestion.

MichaelG.

As promised, earlier ...

For those who may be interested in understanding Stepper Motors:

This is a good place to start

And this is the definitive reference

MichaelG.

Alan.

I do not know (beyond your postings) either you or michael

I also do not know The EW.

Or the problem/challenge being discussed..

Thus I cannot suggest other than in general terms anything.

1. the stepper motor solution for a screw cutting gear train ..might be simple enough to have merit (works for cnc)..

2. as to powerfeed ..."simiple knob for speed switch for direction"...certainly do able...

Much the same hardware for both..

things to note..ungeared stepper motors when unpowered have little or no resistance to movement..so could quite happilly remain coupled when using lead screw in "manual"...

a pickup off the spindle giving a suitable number of pulses could drive the stepper drive board..( and with dividers in the path provide for the "change" wheel function and yes "on the fly" whilst in motion)

In anycase whether a purely mechanical or electro mechanical solution is "BEST" would depend on individual taste...

Hi everyone, perhaps it's time to slow down a bit.

There are some very interesting thoughts that have been contributed here and I'd like to thank Michael and Dias for their time and effort in helping us out. I have looked at the various links provided and several of these devices do seem (to me) to be a very good start to the generic device I had in mind - at least in terms of functionality. Enjoyed your photos Dias (with just a hint of jelousy) some very nice projects here that you've completed and your mill drive is very practical example of what I had in mind..

I will admit to not (quite) understanding how some of these smaller 'stepper' devices handle the stepper motor current requirements (heat etc) when other 'driver' boards (AET?) seem to be much larger - and just designed to step the motor with no degree of 'intelligence'. But there certainly is the core of a good idea there in there - Thank you Micheal for bringing them to my attention..

Personally, I'm in no great hurry to resolve these issues, I'm busy building my small milling head and (for a change) I am managing to stick to this one project - without getting dragged off to new delights at the drop of a hat. I'm afraid I do tend to have a Butterfly tendancy - 'fluttering' from one project to another as I get stuck (or bored) with the current job. So I'm trying to be good (focused) and actually complete the milling head in a fairly linear manner this time. A good discipline to practice occasionally!

Fortunately, it is my Hobby not my Living. So thank you again (everyone) for your input - all noted and hopefully all useful when I get around to focusing on this particular project sometime in the future.

Best regards,

Ian T

For the avoidance of doubt:

In my posting of 29/08/2012 21:45:44 ... "machine-specific" was hyphenated.

I meant exactly what I wrote: " ... no particular interest in the machine-specific detailing. "

Mr Stringer's lathe was an admirable design in many ways, and my "attitude" to it has always been positive.

MichaelG.

"There is a posting from Jason Udall that seems to confirm that my ideas for the operation of the digital slow feed can be acheived, but again no hard details."

Ok My thoughts.

With a suffienctly powerful stepper motor coupled to the ( extended towards the headstock) leadscrew no gear train would be needed and no clutch required since steppers are relativly free moving .

A gear train would allow smaller stepper but more complex coupling arrangement.

An encoder wheel of some type attached to the spindle, maybe even using an existing gear wheel ( pardon my ignorance of the EW ), would provide pulses syncronised with the spindle..

( simplest.. "index wheel I holes per rev..)

these pulses ( produced by either OPTO interuptor or inductive pick up of say gearwheel)

are feed to stepper interface "board"..one pulse (from spindle encoder ) steps lead screw one step ( depending on gearing of stepper/leadscrew) wich coresponds to a fixed movement of leadscrew..( N steps per rev of stepper G reves of stepper to lead screw S inches/mm per rev of leadscrew..thus N*G*S per inch etc.)

Thus leadscrew advances for one rev. spindle I /(N*G*S) inches etc. thus I needs to be large and G not excessive if resonsonble feeds are to be achived.

so far so good.

Varible feed.to produce varible feed you need to " divide" down the pulses so D pulses now produce 1 step of leadscrew (your Knob might be really a multipostion switch)

Varible values of D can be done "on the fly" , in my guess for low volumes( number of units) best handled with A MICROCONTROLLER....

which would also handle foward neutyral reverse from a (as simple as desired) switch(1-0-1) or even pushbutton select.. style at users choice..

once the above is done you can clearly see screwcutting is possible..(to a finite accuracy)..think of metric and imperial encoder "disks" and away you go...

These are all thoughts cosidered for my own SL lathe even more petite .but simple mechanical ( pullies and belts) soulutions would have seemed too bulky..

No I haven't got anyway to wards this myself but the method outlined above is the route I would take when I do. ..

BTW yes "wiper motors" can be reversed but the would need the field coil windings lead out first.(did it with startermotors once)

unless you have a PM type.

7 days is far too less by a wide margin, David! Make it 70 at least!!!

Greetings, Hansrudplf

Alan, the motor I use is an old Lucas, with a wound field, and to reverse I use a 2 pole, three possition switch,on, off, on, to reverse the polarity. Speed control could be electronic, but I just made some resistors from the nichrome wire from an old heater element, and made a rotary switch, and fitted it in a metal box. The drive is from an extension to the wormwheel shaft on the motor via a 10 tooth sprocket, to a 20T sprocket on the mill lead screw. To operate manually, the chain is loose enough to lift off with out needing any adjustment. All you need to do with this system is adjust the resistors to give the speed you want, and match the drive ratio to suit. I run my feed on 17v as that is my low voltage supply around the workshop. IAN S C

If anyone is interested in owning an EW lathe - one has appeared on eBay.

**LINK**

Usual caveats - It's not mine - nor do i know anything about it BTW - Just for info.

Regards,

IanT

Just looked at the lathe above again - there doesn't appear to be any slides present - so it's incomplete as shown.

Regards,

IanT