budget diy cnc controller question

[george uk]

Hi

am a newby so can only offer an opinion, i am building a large machine like you, but a bit more ridged for stone. Like you, i first though get the motors, but, as i was told, WRONG WAY ROUND.

I would suggest



1. Design/Build your frame then gantry ( or pick one of the designs on here, most of them are good enough for what you want to do )

Think about rail sizes, and gantry weight in the design stage

2. Then ask on here about motors/servoes and cards. I was given some very good advice in relation to driver boards on my thread onb here. have a look atg them.

As a general ball park, i think your est of motors/driver and card should be between 500 and 700, depending on what you want to end up with.

The next part being quite important if you want to keep cost down and build easyer.

Do you actualy need a machine that big, As maybe a 4 foot by 4 foot, is cheeper, but a lot easyer to build. When you go bigger, you start running into engineering problems, all are get roundable, but none easy or cheep.

re the Chinees cards you link to

Ther eis an upgraded version of the driver chips, ( V3 ) that seems to get round the problem.

If you do get one of these NEVER GET ONE WITH THE STEPPER DRIVER ON BOARD, always seporate drivers. secondly. If you read up on here, you will realise that a lot of the power packs, sold with these kits, are to low power for heavy use of the motors,

So, for a cheaper 4ft by 4ft, thats not going to be cutting solid material all day, maybe, ther are worth a punt, but, the support on these chiness cards is none exsitant, i know that from experience. and the all in one cards ( with settper drivers on boards ) are a nightmare to use/setup and maintain.

Just my opinion and remember am a newby ( quite good at math and engineering though )

[george uk]

Hi Dave

MAKE = Materials to be constructed from.
WEIGHT = Mass to move IE gantry etc
FUEL = Voltage running motors at.
WHEELS = Pinion Size
GEARS = Ratios

Just to give you a heads up

WEIGHT = Mass to move IE gantry ==== Frame steal 80mm by 4mm or 100mm by 4mm or 5mm. == Gantry, either steal or ally. Its quite easy to calculate the weights, it will be the gantry weight thats important, not the frame

FUEL = Voltage ==== The gantry weight will tell you what motors and drivers are required ( most of the time nema 23/4 sometimes geared. ). ==== also, your power pack ratings are important,

WHEELS = Pinion Size ( or ballscrews, ) Again, your gantry weight/style will help you decide this, 16mm or 20mm if ballscrews i suggest ( i dont know enouigh about R&P ), same with rails

GEARS = Ratios ===== This is about the speed and accuracy that you want from the motors, its a curve, higher speed, less accuracy.

Most supplyers of metals give the the weight per meter, and you might even fine something suitable for the frame ( with adjustments ) at the scrap yard if your trying to save a few £.

My opinion if your going the cheep route.

There is no cheap route with motors and drivers, you will just need what you need, and its machine specific

Spindle - ebay 2.2kw, water cooled with VDF around £ 250, Aldi ( or other cheep place ) cheap £ 30 dremile type. You get what you pay for. The cheap one will not last long on even modrate use, but it will cut/mill thin stuff ( slowly ) ( just add a cooling fan ), If you got the mounting plate right on the Z, you could even use a cheep router. You might try with the cheap one, to convince yourself you need to pay for the more expencive one, and £ 30 is not a big loss,

Software -- for what you want to do, Mach3/4 would be good ( £ 120 ), there are cheaper alternatives, some free, but unless you have reasonable programming skills, and a good understanding math, you wont beat mach for the support for newbies. In all honestly, with mach, the £ 120 is worth it just for the support,

I hope with what i have put above you have an idea at what parts you can go cheeper on and what parts you can not. If i was you, i would give myself a scrapheap challange, and go looking for something you can use for the frame, your luck might be in. and what you save on that, put into the electronics.

[JAZZCNC]

FUEL = Voltage ==== The gantry weight will tell you what motors and drivers are required ( most of the time nema 23/4 sometimes geared. ). ==== also, your power pack ratings are important,

[COLOR=#333333]WHEELS = Pinion Size ( or ballscrews, ) Again, your gantry weight/style will help you decide this, 16mm or 20mm if ballscrews i suggest ( i dont know enouigh about R&P ), same with rails

No disrespect meant George but what your doing is dangerous and quite missleading to new users.? . . . . I'm tempted to say Blind leading the blind but I know you have done lots of reading upto now but still you need to be careful what you post to new users because you can send them in wrong direction quite easily, all done with good intentions I know but still misleading and wrong.

For instance you Say Mostly Nema23 and sometimes geared.!! . . . . Actually Often for a 8x4 machine using Rack n pinion then Nema 34's are prefered for there higher torque and 99.9% of the time you'll always have a gear ration of at least 2:1

Also suggesting 16mm ballscrews for a machine this length is totally wrong unless very specific things are done, like using a Rotating ballnut. I won't use 16mm screws much over 1500mm and wouldn't dream of using a 16mm or 20mm rotating screw at nearly 3000mm.

Not picking on you here and know your only trying to help but much better advise rather than trying be specific, unless you have first hand experience is to suggest Nothing and tell them to go look around and learn. Then ask questions that are more informed and specific to there needs.

[george uk]

hi jazz

I was suggesting options for 4ft by 4ft table, up to a full size table, and just trying to give him a general idea. . If you read my post, i had suggested that, i also said i did not know enough about R&P.

If price was not an issue from him, i would say 25mm rails and screws and servoes, but he is clearly looking for cheaper options, and it is that i offered advice on, but he clearly want to have a crack at this on the cheap. and it is doable, i was just trying to help him understand, that he can not go cheap on motors and drivers. I do have some experience with that type card

ther are many wrong approaches to machine building, but there are also a few right ways. not just one. If it was like that, you would just point him to this thread, and say build that

http://www.mycncuk.com/forums/gantry...g-machine.html

Well engineered, well built, and he lists what he would change

But he is clearly looking for cheap options, and wants to hobby build. and remember were the hobby built cnc machine started, For me, a graph plotter with a drill strapped to it, 1989/90 machine running it was amstrad 1512, and we had to write the actual code that run it, My current main hobby ( robotics/electronics ) and previous hobbies ( UAVs and RC stuff, kart racing ) all work on very fine tolerances, am used to having to get things a lot more refined than is needed for cnc design, granted, on a smaller scale. I do clearly mark any post that i have given advise on thought that i am a newbie,

[JAZZCNC]

hi jazz

I was suggesting options for 4ft by 4ft table, up to a full size table, and just trying to give him a general idea. . If you read my post, i had suggested that, i also said i did not know enough about R&P.

Exactly so best not to suggest anything.!! . . . There's a saying . . "Better to remain silent and be thought a fool than to open ones mouth and remove all doubt" . . . . . Not 100% relavent or possibly fair but I do like it. .Lol

If price was not an issue from him, i would say 25mm rails and screws and servoes

And again you'd be wrong because servo's are not always better, The rails most likely over sized and screws wrong selection for this size machine without special considerations.

ther are many wrong approaches to machine building, but there are also a few right ways. not just one. If it was like that, you would just point him to this thread, and say build that

http://www.mycncuk.com/forums/gantry...g-machine.html

Well engineered, well built, and he lists what he would change

Again that would be wrong because it's a completely differant machine which would be inpracticle at this size required and totaly over engineered for cutting wood.

So again please I'm not picking on you just trying to show that throwing advice around without considering all the variables and relevancys can be disatrous for a new person.!! . . . . . . . I know this from helping many that have unwittingly fallen foul of such good intentions.!!

[Lee Roberts]

Mistake No1 Assumption is the Mother of all Fuck UP's

A-Men to that !

Exactly so best not to suggest anything.!! . . . There's a saying . . "Better to remain silent and be thought a fool than to open ones mouth and remove all doubt" . . . . . Not 100% relavent or possibly fair but I do like it. .Lol

Now I have to admit, that is a rule I do practise.

However George, there is no certainty that a thread, post or even a question will get replied to, only probability! so actually I think you were correct to contribute what you could/did. This is a discussion forum after all.



.Me

[JAZZCNC]

A-Men to that !

Now I have to admit, that is a rule I do practise.

Well you should keep practising then because from this below you need to.!!

However George, there is no certainty that a thread, post or even a question will get replied to, only probability! so actually I think you were correct to contribute what you could/did. This is a discussion forum after all.

How can you say it's ok to give INCORRECT specifics to a question with no details.? . . . So for discussion sake it's OK to miss-inform and nothing be said about it.??. . . . OR . . . is just the fact I've said it that makes it OK.????. . . . . . I FUCKING GIVE UP GOOD LUCK PEOPLE.!

[george uk]

hi Jazz

Originally Posted by george ukhi jazz

I was suggesting options for 4ft by 4ft table, up to a full size table, and just trying to give him a general idea. . If you read my post, i had suggested that, i also said i did not know enough about R&P.



Exactly so best not to suggest anything.!! . . . There's a saying . . "Better to remain silent and be thought a fool than to open ones mouth and remove all doubt" . . . . . Not 100% relavent or possibly fair but I do like it. .Lol

Honestly mate, with that attitude, we never would have walked out of the cave. Jazz i do respect your advice and have read through loads of your posts and advice to other people and assimilated lots into my own design, but, you can not consider people fools becuase you consider them wrong, I think you have just misread what i have been trying to explain to the bloke. They do say " fools rush in "

Dangerous Dave - am trying to suggest this to you

1. You can not go cheap on the motors and electrics, Decide on a frame size, gantry style, then let that choose for you
2. Machines above 4f are a lot harder, whereas, the machine i pointed to, and suggested, Is probley a good all round starting point. there art a few things you could make cheeper, like the bed, single baerings. You could even try find the bed at the scrappy, and mount and true the top like He shows in his thread.

Originally Posted by george uk
If price was not an issue from him, i would say 25mm rails and screws and servoes



And again you'd be wrong because servo's are not always better, The rails most likely over sized and screws wrong selection for this size machine without special considerations.

Again, you dont seem to have read the post, i said that because you was assuming on the previous post that i had ment the smaller screws and motors for a full size machine, and i was trying to emphasise that his main consideration is costs, Also, if a persons not able to engineer the machine fully, then upping the rail sizes and screw, is one way to get over that.

"Better to remain silent and be thought a fool than to open ones mouth and remove all doubt""Better to remain silent and be thought a fool than to open ones mouth and remove all doubt"

Barnes Wallace, Brunel , mary bell, Copernicus, Galileo, Bor, --- a long line of people that was considered fools,

[JAZZCNC]

Honestly mate, with that attitude, we never would have walked out of the cave. Jazz i do respect your advice and have read through loads of your posts and advice to other people and assimilated lots into my own design, but, you can not consider people fools becuase you consider them wrong, I think you have just misread what i have been trying to explain to the bloke. They do say " fools rush in "

The "Fools" quote was a Joke which i made clear. I DON'T Consider you a FOOL but I DO 100% Know your WRONG and I'm the one often holding the hand out to help those that have took Duffy info all be it given in good faith and with no harm ment, But still wrong and often costly and some times dangerous.
Information and help like what's below is great Advise and perfectly fine but you can't be specific and advise motors,rails etc with no information to go on like in this case.

Dangerous Dave - am trying to suggest this to you

1. You can not go cheap on the motors and electrics, Decide on a frame size, gantry style, then let that choose for you
2. Machines above 4f are a lot harder, whereas, the machine i pointed to, and suggested, Is probley a good all round starting point. there art a few things you could make cheeper, like the bed, single baerings. You could even try find the bed at the scrappy, and mount and true the top like He shows in his thread.

Again, you dont seem to have read the post, i said that because you was assuming on the previous post that i had ment the smaller screws and motors for a full size machine, and i was trying to emphasise that his main consideration is costs, Also, if a persons not able to engineer the machine fully, then upping the rail sizes and screw, is one way to get over that.

This is exactly my point.!! . . . . No I didn't pick this up and neither will many others because you wasn't clear enough and neither did I see any mention of a 4x4 machine before you quoted specifics.!!. . . . . . All this Un-specific Info is confusing and misleading to new users.
Even now your comments about compensating with larger rails and screws for lack of Engineering is just WRONG ADVISE and all this would lead to is a very Expensive under performing machine or worse failure.!!

I'm not saying this because it's an Opinion of mine, I say it from lots of experience dealing with folks who have mis-understood or not read enough etc. Which you could say "More fool them" but my point and why I jump on this sort of thing is because it does happen and it doesn't need to happen so if folks just held off or asked for more info before posting then others wouldn't fall foul so easily.

Again DON'T think you a fool and I appologise for it coming over that way.!!. . . .

[george uk]

The "Fools" quote was a Joke which i made clear., ... again DON'T think you a fool and I appologise for it coming over that way.!!. . . .

I never took it that way, an i prefair people being direct, and i was being a bit cheeky in the reply,and i have just read back my own reply.

Barnes Wallace, Brunel , mary bell, Copernicus, Galileo, Bor, --- a long line of people that was considered fools,

Gosh, that makes me sound like i live so far up my own backside that i would need street lighting tro find my way out. So no worries,