taig and sherline mills to the UK

They list 4 in the ME advert One is a silly type 16? at 36N/cm [ 31 oz in ]

Two are 23's 180N/cm [ 160 oz/in ] 4.5Volt at 2.5A per phase, 8 wire, twin shafts. Both 30 quid only difference is one is 6mm shaft and one is 1/4" shaft both

25mm long

Last one is type 23 220N/cm [ 195 oz in ] 7.5 volt at 2.5 amp, 8 wire, twin shaft, 10mm diameter x 30 long. This one is £39.50 Presumably VAT inclusive as it's not mentioned

-- Regards,

John Stevenson Nottingham, England.

I have found a suiatable psu I think, It's from rs components. The cod

is 466-5875 its 24vdc 2.1 A. Or do I need one with a higher amp rating There are some open cage ones as well for a bit less that look ok. Is it better to get a 3v or 6v set of stepper motors? Reading th xylotex pdf it says voltage doesn't matter, but says the upper limit i

3.6

-- milg

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Milgo,I gather from reading your post's you are either very young, on speed, hyperactive or addicted to food colouring. You need to slow down and do a LOT more homework otherwise you are going to finish up wasting a lot of time, effort and money. Steve Blackmore gave you a link to go to on the Gecko drive web site for some white papers that explain all about steppers, drivers, power supplies etc. Download this and read carefully. Then re read it. Then come back and ask anything you don't understand

-- Regards,

John Stevenson Nottingham, England.

While I generally agree with this, it should be pointed out that "old" is not always "bad" and "modern" is not always "better."

It does depend on what you need. For example, at high speeds and power you will find that chopper designs are loosing just as much power inside the motor due to "iron losses" (eddy currents, etc...) as those old ballast resistors were pulling. A properly tuned linear driver may dump a lot of heat through resistors and power transistors but the motor will run smooth and cool.

The old linear stepper drivers give very good MOTOR performance, especially when you need to accelerate to high motor speeds or need smooth "stepless" operation at very low speeds. Torque ripple from voltage chopping is removed, also gone is the supply ripple from chopper recirculating currents. Expensive high-speed high-current diodes are not needed. Eddy currents and copper losses, and recirculating diode losses are reduced and the motor gets LESS heating with linear than with a chopper supply, although the driver gets more.

Think "large audio amp"... Linear is a great way of getting an exact-shaped high freq current into something inductive like a speaker or motor. Ask "Boston" or any other audiophile band about analog amps.

Another benefit of linear is Current Ramping; the analog current control can have an RC network, giving a "ramp" from one current step to the next. See:

for some 'scope screens that show this.

Ramping rate between steps is selectable by the capacitor size. Ramping is much smoother than hard edged steps, and reduces excitation energy that causes "singing" and resonance. With ramping, more of the motor energy is converted to forward rotation, unlike the "two steps forward one step back" effect of hard ringing steps.

The ramping can be tuned for main operating speed to give almost stepless operation and very quiet and smooth rotation. It can be set VERY slow so even motor speeds like 0.5 rps can be made very smooth! See:

The rule is TANSTAAFL and you have to waste some energy somewhere with steppers. The motor isn't always the best place to do that.

May I suggest the linistepper kit? $25 each in a set of 3... Shipping out of the US is available with pre-paid orders.

Are you recommending linear stepper motors for the CNC application?

Steve

If that's the case why have all commercial machines that still use steppers dropped unipolar drives in favour of chopper driven systems?

You'll always get the enthusiastic amateur who thinks his PIC driven system is better than a commercial chopper drive ;)

Not all drives "full step" Take a scope to the output of a modern microstepping controller and all your arguments are answered.

Have you read the stepper white paper?

I just have a lot of time on my hands, sorry. Erm im 18 if you call tha

young? I got in contact with simply CNC and they sell the xylotex boar with 3 230oz/in motors for £280 including delivery. So I think I am se on that, so it is now deciding on the power supply. I will take you advice and read all the documentation first before I hassle you. Like said earlier I am just a little apprehensive about ordering the wron stuff, which is probably why I am posting all the time

-- milg

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So in that example, would the system be pulling the same or larger overall supply current for the chopper system as the ballast system?

AIUI, the stepper motor originated as a linear design, to be fed by two AC signals in quadrature. That certainly seems close to the waveforms displayed by the guy for microstepping.

Don't pay Mr.Stevenson too much heed - he's an extremely bad-tempered and foul-mouthed individual as the Google record for this NG shows. He cannot but help resorting to the language of the school playground.

Age is unimportant - Mr.Stevenson having the emotional age of a 5-year old being a case in point.

The Bristol Exhibition (today and tomorrow remaining) promises some CNC stuff.

Don't worry about asking questions in this NG - it's what it's there for.

The only thing to watch out for is not to drive the stepper motors directly from your PC - select an outboard controller which does the counting of steps.

No need to apologise 99% of the people on this board are quite prepared to help you but you also have to help yourself. People like Tony Jeffree, Steve Blackmore and myself have been there, done that made the mistakes and got the Tee shirt

That price from Simply CNC isn't bad but you could save about £40.00 by buying Arc Euros motors and the board from SimplyCNC.

A power supply is easy to build, it's a transformer, a bridge rectifier and a capacitor. All the information on what sizes, power and components are in one section of those white papers mentioned before. A power supply can be built for a fraction of what a bought one is available for. Maplins are also far cheaper than RS on a lot of components.

I don't know whether he's still posting or not but we have [ or had ? ] a troll on this board called Airey Bean. A lot of us run a piece of software called Newsblock that gets rid of all his posts and any replies made to them.

He's just a sick troll with a history of metal illness, It's just best to ignore him as often he quotes wrong information.

He's a photo of a Taig I converted from a manual machine a while ago

-- Regards,

John Stevenson Nottingham, England.

Those motor mounts look nice. I am going to stay clear of building a psu myself, I am sure its easy when you know how :) I just wanted to confirm something, on the xylotex board there are variable resistors to control the current right? And you set that to the motors specification? So if I have a stepper rated 1.8A then I can run that off a psu with 2.1A and adjust the resistor? But I cant go above 2.5A?

Was it on this newsgroup, or maybe somewhere else, that a frenchman asked for advice because his Sherline(?) (without the CE certification) had already been sitting in a customs depot for months because a zealous customs guy wouldn't release it unless he got a CE cert for it first (costs thousands to do, needs to be official lab etc.), even though the US equivalent was probaly just as rigorous They wouldn't even let him remove the motor,IRC.

Hans

Milgo,

I think that Mr.Stevenson shows himself to be a liar when he says he's ignoring me totally! Why else would he respond in such a manner when I have not contributed to this group for some time, and so rapidly after my post in critique of him? I suspect that he has wound everybody else up, but is continuing to monitor me in secret.

What an idiot he is! Yah! Boo! Sucks! to you Mr.Stevenson!

NNNNN!

The true story actually has its genesis in this very subject; that of stepper motors. I contributed to a discussion bringing to bear my relevant professional experience. Mr.Stevenson tried to argue the toss, but the plain facts were that he simply did not understand the issues being discussed. When he didn't get his own way, he resorted to some very silly and childish outbursts which did no more than to make him look a fool. I chided him for what was unnecessary infantile behaviour in a public forum, and he proceeded to show his true colours again and again.

I think that Mr.Stevenson showed his true colours to you, when he uttered his gratuitous and unnecessary remarks about your obvious excitement. However, you must not take my word for it, you must make your own decision and Google is an excellent archive for that purpose.

There really is no excuse for posting insulting and offensive remarks into a NG to which young people have access, or, indeed, to address such remarks to admitted young men such as yourself. I severely criticised him then, and I do so again....Grow up, Mr.Stevenson!

As to the topic of mental illness, perhaps it is Mr.Stevenson who is himself exhibiting the Freudian coping mechanism of, "Projection"?

I've never to my knowledge posted wrong information. Perhaps Mr.Stevenson would care to put up or shut up? Perhaps he would care to buy me lunch tomorrow at Bristol? No? Thought not!

I have never trolled in any NG. Everything that I post reflects my independent and honest opinion. I exhort you to do the same.

I also exhort you to contribute in a polite and considerate manner into the NG, as indeed you have done so far, because international public fora for specialist interests really are not the place for childish bickering of the style of Mr.Stevenson.

No doubt he will go out of his way to be nice to you, but the Google record is there for all to see. Beware the wolf in sheep's clothing.

As I said before, please feel free to post any request for information into this NG, irrespective of the level of your background reading - that's what the NG are for. I suspect that the reason that Mr.Stevenson sent you off to do some reading is that once again he doesn't understand the issues involved and doesn't want to be shown up!

Dear Mr Bean,

I do not use Mr Stevensons program... Unfortunatly it's not compatible with other anti spam measures I have in place.

I note that you started your contribution to this thread with a post who's first sentence was a personal attack on Mr Stevens.

In your second post you use such phrases as " Yah! Boo! Sucks! "

Could I please ask you to refrain from personal attacks and infantile comments in posting to this group.

I would support your right to self-defence, but in this case have not seen any attack.

I will continue to read with interest any technical points you contribute, reserving my wright to my own opinions.

Turning to technical maters ( probably where I should have started :-( )

I am interested in timing problems in machine control... Mostly on PLC's rather than PC controlled equipment.

You have obviously had some bad experiences with this, I am interested to know what programs you have had problems with, and weather you have had any experience with the software Mr Stephenson was talking about.

I know some of my PLC programs require adoption to get them to run correctly at high speed, and wondered if the programs you had used might have run into similar problems.

With PC programs the complexity of windows would make the simple jigery pokery I do with PLC's a lot more difficult or even impossible.

Hans van Dongen I have definatly decided not to import anything now

After considering everything that could go wrong, like you mentioned Airy I dont know the ins and outs, and dont really want to get dragge into anything :) Perhaps you could point me in the direction of a appropriate 24vdc power supply from rs components? Just to say, I do appreciate I need to do homework by myself but lik you said john, you have the tee shirt. So I would rather someone wit experience could point me in the right direction

-- milg

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This shows your mental age.

You quite unnecessarily and incorrectly abused him with your ignorance.

You are the one that does this all the time - you are blaming John for your own failings.

Your pseudo science does you no credit but only serves to underline your inadequacy.>

Must mean that you do not know what you are posting as most of your postings that I have seen have just been rubbish.

This is a joke ? isn't it.

Take your own advice - John has only ever retaliated after you abused him.

If you learnt how usenet works you would then know that is the best way to help someone as it put information at their fingertips.>

Nice looking job John! Are using belt + pulleys from stepper to lead screw?

Steve