# CNC mill



## Julian (Dec 11, 2008)

Hi Guys,

Well on in the conversion of my X1 to cnc. Made new leadscrews, nuts, anti-backlash, motor brackets andthe control box complete with power supply. Will post pics when its done and also when I can find the camera under all the mess.

I am running it on mach3 at the moment but got a small problem. The motors double or treble their speed every time the mouse is moved. Anybody got any idea what the cause is before I start ripping it apart to find a fault?

Thanks

Julian.


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## kuhncw (Dec 11, 2008)

Hello Julian,

Sorry, I don't have an answer but you might want to also post your question on these sites where a lot of people using MACH hang out. Perhaps you've done that, but if not here are the sites.

http://www.machsupport.com/forum/index.php

http://groups.yahoo.com/group/mach1mach2cnc/

Regards,

Chuck


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## John S (Dec 11, 2008)

??

Any chance of any more info ?

Is this jogging, running a program or what?

John S.


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## Julian (Dec 11, 2008)

Hi,

This happens when running a program. I will check if it is while jogging tomorrow.

Have just joined Mach forum tonight.


julian.


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## John S (Dec 11, 2008)

Two things to check.
Try another keyboard and in Mach go to Operator [ top menu bar ] > then Check Config and see if you have any pins conflicting.

John S.


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## Dhow Nunda wallah (Dec 12, 2008)

I'm sticking with an old workshop computer to drive my router, uses a PS2 mouse.
I do seem to recall something on the mach forum tho, regarding USB rodent/keyboard conflicts.
Worth consideration?
Are you using USB kbd and/or rodent?

Cheers,
Lin


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## Julian (Dec 12, 2008)

Checked and it also does it in jog. Checked with EMC2 on linux and that is not affected so must be software rather than hardware fault.


Not got usb mouse or keybd. Clean installation of mach and winxp and no connection to internet. Can find no conflicts in fact have turned off all inputs and outputs except for the motors. Got no limit or home switches yet.


Julian


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## Julian (Dec 14, 2008)

Hi All,

I have a low tollerance of things not working so have moved away from mach3 for now. May go back later but may not. 
WHY?....................Cos I have installed a free program called 'CNCMaster'. It was writen specifically for model engineers. It includes several wizards for wheels, flywheels, gears, splines etc. It runs gcode and all the others too. 

My motors are running better, smoother and quieter than under Mach3. The pins it uses did not match those listed on my breakout board but that was soon changed to suit. If you're looking for a free efferctive cnc program for your mill or router table check this out. 

http://www.colinusher.info/Software/index.html

. It can be installed without a mill and tried to show its capabilities.

I have no connection with the software whatsoever except for a wish thaty I had written it!!

Julian


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## Julian (Dec 22, 2008)

Just a couple of update for anyone interested.

I have worked the mill on CNCMaster and it works very very well.

I have cured the problem with Mach3. I ran through all the instructions for optimising XP found on the Mach3 site. This includes pushing XP into standard mode, clearing all starups etc. The full list is at:-

http://www.machsupport.com/downloads.php     Bottom of Page.

Appears to work just fine now.

Julian


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## HS93 (Dec 22, 2008)

Hi any chance of some pictures and info on how you Made new leadscrews, nuts, anti-backlash. I am in the middle of doing one and the big let down is the standard nuts etc

Peter


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## steamboatmodel (Dec 22, 2008)

Just a general question, Do any of the programs run on a closed loop system, where there is feedback as to where the axes are?
Regards,
Gerald


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## RonGinger (Dec 22, 2008)

That depends on how you define 'closed loop' In the strict sense, only very high end commercial systems really do what you are expecting.

Some will say that a servo motor is closed loop, but it is only a loop with the controller. The program still issues move commands and expects the servo to make the right move.

In my view this is one of the most common holy wars of the home shop CNC game. Its usually brought up by new guys, mostly ex-software guys, with no practical machine experience as a worry about using stepper motors. The fact is there are tens of thousands of CNC machines with stepper motors making reliable parts all day long. A stepper motor correctly sized, and operated within its limits will NEVER miss a step. Sure, if you try to take to big a cut, or run it to fast, it will loose steps, or maybe just break the tool. My suggestion is 'dont so that'

Mach has an optional board, offered by a guy named Ron Rodgers, that uses encodes to provide a feedback to a mach plugin. You set a tolerance value into the code, if the hardware senses the actual position is out by that value it pulls an Estop on the system. This does work well and is a close, and inexpensive, approximation of real closed loop.


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## steamboatmodel (Dec 23, 2008)

Thanks Ron,
I am an Retired CNC Programmer/Operator, and all the equipment I ever worked with had feedback, but most were "very high end commercial systems ". I was used to pushing the machines fairly hard. Looking at the setup on most of the home conversions I realize that you would never be able to push the systems the way we did in industry. The board offered by Ron Rodgers sounds like a good idea.
Regards,
Gerald


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## John S (Dec 23, 2008)

Ron's Rogers board is more of a stop gap measure.
As Ron Ginger says if it detects an error it pulls the plug but all that does is ruin the job as it stops out of position.
A well designed stepper driven machine should not loose steps.

There is more written about this by armchair machinist and purists than people who actually use machines for a living.
Remember most of the Appollo program was machined on Series 1 Bridgeports on stepper driven 1/2 step systems but they still got by NASA certification.

John_S.

.


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## steamboatmodel (Dec 24, 2008)

John Stevenson  said:
			
		

> Ron's Rogers board is more of a stop gap measure.
> As Ron Ginger says if it detects an error it pulls the plug but all that does is ruin the job as it stops out of position.
> A well designed stepper driven machine should not loose steps.
> 
> ...


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## Julian (Dec 30, 2008)

Hi.

If the motor and controller is powerful enough there should be no need for feedback. Feedback would only be needed if the motors were struggling for some reason either not enough power or the machine too stiff or obstructions against a drive or feeding too fast etc.... I am happy that my motors are going where they are told at the moment. 

One obstruction I have found that makes the system struggle is swarf. I have just made a name placque from brass but do not yet have a system of removing the very fine swarf. It is very fine but jams in any pockets you cut so either causes missed steps or snaps the bit. I am about to rig some sort of vacuum pipe to the mill to extract everything as it comes off the cutter.

Julian.


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## BobWarfield (Dec 30, 2008)

Aha, the sacred Servo/Stepper/Open Loop/Closed Loop Jihad has made it here!

I have both. There are good arguments for both. In the end, I have a hard time not going for the servos if I can afford it. Just as we can say NASA used stepper-based systems back in the day so therefore steppers are good, we can also say there are almost no stepper-based VMC's made today, so therefore servos are better. In fact, the servos way outperform steppers in most cases, they just cost more, and you may not need (or be able to take advantage of) that extra performance.

We can argue that we don't care about that extra performance, and we may not, but let's not kid ourselves that there isn't even the _potential _ for the performance or that it won't matter to _anyone_.

I agree with most of what kf2qd says, but I don't agree on the cost point. A servo-based system is more expensive, but it isn't $1000 per axis!

For example, my IH Mill runs homeshopcnc servo motors at a cost of $235 (I got the fancier ones, but they have one with encoder for $199 if you're pinching pennies) for 850 oz in motors, which are pretty stout. Equivalent stepper motor might be $130 from the same place, so you save circa $69, the cost of the encoder. Here are my servos:






Add a Gecko servo drive 320 at $114, which is the same price as a Gecko 201 stepper drive, so no incremental cost there.

The last servo specific piece I use is a board from CNC4PC called the "Master Control Board". It manages the servo fault signals from the Geckodrive and costs $48. You wouldn't really need one with a stepper system, although it could be used to manage your E-stop and limit switches. The nice thing it does for servo users is it manages servo fault signals so that a servo fault looks like an E-stop. What does that mean?

A servo fault happens when the encoder indicates that the motor hasn't been keeping up with the commands issued by Mach 3. On a Gecko 320, the fault is triggered if the encoder falls more than 128 steps behind the commanded position. For my IH mill, each step is 0.7 of a tenth, so an error of 128 means that axis is off by about 9 thousandths. Note that this will differ based on the leadscrew pitch, encoder counts, and belt drive ratios for your machine, but it gives you an idea.

In practice what happens is, I run the CNC program, and if the servos don't fault, I know I was within 9 thousands, and probably a lot better, of what the program intended. Equally as important if not more so, the program may have gotten off by nearly 9 thousandths at some point, but with a servo system, it can "catch back up", so the error is localized and doesn't carry through all subsequent moves. If I was running a stepper system, I might be off by a lot more, and the errors become cumulative. Once I'm off, the system never catches back up again. In fact, if I start a whole new part without rezeroing, the error lives on for the new part too!

With the servo fault, I can see by where the machine stopped what it was doing when the error added up to too much. It's pretty easy to turn down the feedrate (potentially just for that part of the program and not the whole program too), restart the program, and try again. If the same happens for the stepper, I have to start measuring the part to find where the error begins manually. I may not even be able to measure the beginnings, because they may have been machined off. In fact, with the stepper, I have no idea if there error is due to lost steps or some other source of error in the machine. This makes tuning up your programs a lot harder with a stepper system than a servo system.

It would be ideal if the controller could actually log where the errors occurred, how far off things got, and even let me set in software the servo fault limit (maybe I want to fault if its off by more than a thou, or perhaps I'd like to be able to change that tolerance at different places in the program). It's be even better if the position signal made the control dynamically slow down or otherwise take steps to "do better". I can't really do that with the rig I describe. I can do a little better with the Rogers board, but it isn't clear to me how to make that board work without even more encoders. It's more of an add on to a stepper system. It's probably not possible at this stage in Mach 3 development to do what I describe at all, but what I do get seems pretty good to me.

In practice, I suspect steppers lose steps a lot more often than most stepper users think. Many people complain that the Gecko 320 is "too sensitive" to servo fault. Given that the fault doesn't happen until they are off a few thou at least and maybe more, those same people are obviously used to running stepper systems that silently get off by that much and keep going.

It can get a lot worse too. Servo faults can be caused because the program runs awry and the cutter is plowing into vises, clamps, tables, and whatever else gets in the way. The stepper will keep chugging through it even after the cutter breaks and there is a smoking ruin. It isn't going to take too much of that sort of thing before the servo will fault and things stop. 

So to conclude this rather long essay, do I insist only on servos? No, not at all. I have two machines set up for steppers and one for servos. I'm happy with each. I'm just saying that if I can afford the added expense of servos, I think they're better in every way. I don't see a down side to them other than the cost. That cost is quantifiable. On my mill, it has cost me an extra $210 to buy 3 servos instead of 3 stepper motors, and another $48 for the Master Control Board. I think the extra $258 was well worth it on this mill. Your mileage may vary!

Cheers,

BW


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## steamboatmodel (Dec 30, 2008)

Thanks Bob,
Yours and kf2qd's explanations is what I was looking for, I have only run commercial CNC equipment with Servos, and want to explore all options.
Regards,
Gerald


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## John S (Dec 30, 2008)

First a couple of clarifications.
Yes the Bridgeport's did have massive steppers on them, got loads lying about here and they were only 850 to 1200 oz in on a type 42 motor.
Modern type 34 can piss all over these so it's not the motors. the Bridgy controller / driver unit was absolute crap. This is the reason why there are so many good mills out there, they never wore out because they spent more time broken down, crash one into something and it burnt the output transistors out - full stop.

They were only full stepping and could hold 0,001" but even in those days 1 thou to NASA was still the same thou it is today.

Bob put some good points about the difference between steppers and servo's and I have no beef with his explanations, they are 100%.

One point that has been missed though and lets face it this IS a hobby forum is the skills needed to built both systems.
Steppers are cheap and simple easy to mount usually on existing hardware as they develop maximum torque at low revs.
Servo's develop max torque at high revs meaning you have to gear an axis down to get any sort of power out of it.

Quoting max feed rates isn't everything in CNC as any G00 moves are not cutting and only costing you.

The main difference for a beginner is the complexity of the servo system. There are not many good servo drivers out there for one and all rely on encoder feedback, to a beginner this often also translates to noise.
Read the CAD_CAM_DRO list, Gecko list and CNC Zone and most of the beginners problems are caused by electrical noise.

There is also a missing link at the moment in that the larger servo motors require analogue inputs but affordable controllers use step and direction, Gecko drives can't power the big servo's like the BOSS 2's and Mach can't power the larger Fanuc, Baldor and Siemens servo's drives.
Rutex tried and failed, the Pixie convertor card whist seeming to work was withdrawn so there is a gap.

CNC like any new venture is a steep learning curve and the sooner it flattens out the sooner you actually start learning and enjoying. Doing a simple stepper system to cut your teeth on and then progress if far better than throwing yourself into the top end, never getting a grasp of it and then feeling let down.

Incidentally my big mill, a Beaver, the same size as a BOSS 2 and built with the same stepper motors as the BOSS 1's at 850 ox in direct onto 0.2" pitch ballscrews has been running all day today drilling circular hole patterns with a 2.5mm drill.
These holes are virtually touching and any errors show up immediately, add to this the machine has graduated dials on as it shared some components with it's manual stablemate so when it goes home it's easily checked. Todays run was 11,208 holes and it's parked back on 0,0,0 two drill used, tomorrow it will be doing the same but different job and on 3.12mm holes.

JS.


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## BobWarfield (Dec 30, 2008)

No question about the complexity of servos being higher. And the noise issue is an EXCELLENT point! Noise is touchy to diagnose and annoying as heck because it can be intermittent.

FWIW, I built my first CNC on steppers. Maybe for a first machine steppers are the way to go so you can't start having some fun before you've had to master too much complexity.

Cheers,

BW


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## shred (Dec 31, 2008)

Hmm.. my little Taig CNC has a basic servo kit on it. First time I'd CNC-ed anything, and it was bolt-up, plug-in, turn on, send G-code. It was within $100 of a 3-axis stepper system when I got it a few years ago. I don't think it's vastly better or worse since there's no actual scales providing position feedback-- it just faults if it can't move to where it's supposed to for whatever reason (hit a stop, broke a bit, whatever)

For somebody like me that wants a reasonably-baked solution to make parts on a little machine and not particularly care about how many in-oz of this or how fast the theoretical max ipm is, I don't think it matters enough to care about, just get a combination that works. The people that have the most religion around drivers and servos and steppers and such seem to be the people that rarely make anything that isn't another bit for their CNC machine. Building and tuning CNC machines as a hobby into itself is great for some, but not my cup of tea.


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## BobWarfield (Dec 31, 2008)

Be careful to distinguish religion from engineering, shred. If you just, "get something that works", but don't understand why it works, that sounds to me like religion. If you take the time to understand why, that sounds more like what I think of as engineering.

I find it's easier to get something that works if I know what's really going on than if I just try to compare which marketing hype sounds better or which customer group makes happier noises.

But that's likely just me, and I am, after all, an engineer with an interest in how all things work.  ;D

Cheers,

BW


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## shred (Dec 31, 2008)

Spoken like a true zealot   .. just kidding.. It's like hot-rods and daily-drivers

Some people like to build hotrods, I like to go places. I know how a car works. I don't care what the bore and stroke of the engine in my daily-driver is.

Same for the CNC. Does do what I want? Yes. Can I debug it to a reasonable extent if it doesn't? Yes. Done deal.


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## jack404 (Dec 31, 2008)

Bob

i'm sorta with Shred on this

i'd love to buy a off the rack working cad/cam system i can use to make small parts from hard steel

i dont wanna have to learn this and that and the other to make it do that

i expect i'll have to input dimentions etc 

a lot of this i can send out, for $120 i can get a disk back with the part scanned or the drawings input in g code

i load the metal and set the point and hit run and maybe turn it over

the technology it there

just my bank account aint up to it yet so i'm looking and experimenting hard on the cheap

i know enough to be dangerous and learning as i go 

folks are doing it, and have been for a good few years.

its not rocket science , its not religeon

its a tool, 

the electrical bits defy my understanding

but i can work a pc and software programs to make ajustments to drawings and save them

so do i need to know the rest?

i think the process is easier if you know, sure..

but to set the time aside from everything else i am doing to learn it as it should be learned 
to build from scratch , i just cant do now or the next 5 years

i learn a lot here and other places

i now have a budget and time line for this project ( CNC 10" X 17" Y 10" Z Axis)

it may upset folks but i dont need to be a chemical engineer to know how to work cement

do i need a sparkies cert. to have a power tool?


Bob, technology has evolved enough to allow the lesser brained of us ( me included) to delve into area's we would not otherwise be able too

CNC for the home shop / small business operator is real, just expencive  but DIY is not outside the realm of the knowledge challenged either

plus i have a few mates, ;D ;D ;D and i make a mean home brew

so i think despite me not being a expert, i will end up with a deeeeecent working system ( maybe the Mk. 47) but along the way , "pick up" the knowledge / skills i do not have today

book or do theres few ways a few ways to go i reckon

i think i can teach anybody a few different jobs

no schoolin required

from what i've seen here i think theres a who pile of folks here that are the same in other jobs or skills

not knowing all the in's and out's of something or how it works dont mean you cant use it


hope i aint ticked too many folks off

cheers eh

jack


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## John S (Dec 31, 2008)

The best way to get into CNC is to convert a rotary table to stepper drive.
It's basically one axis of a CNC, it's cheap to do and nothing is wasted even if you don't progress to a full CNC as it's so handy to use on a manual mill for indexing and gear cutting.

Probably most won't have a lot of trouble over the mechanical part, it's just a motor hung onto the end with a coupling fitted inbetween.

The electronic bit requires a power supply, for a small 6" unit then one of those 24 volt laptop power supplies will do.
A single axis driver is the next bit, plenty of these about dependent on where you live, the stepper motor we have mentioned.

All that is left is the controller. Mach 3 will run a single axis in demo mode as you don't need that many commands, TurboCNC is available for anyone with an old computer that won't run Mach and there is a division rogram on the web that is written for clock makers.

JS.


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## RonGinger (Dec 31, 2008)

The hobby world has come a long way. A few years ago there was no choice, if you wanted a hobby CNC machine you had to build it.

Today there are several vendors of ready to run packages. Seig now sells an X3 ready to run- it comes with ballscrews, motors, drivers, etc, even the Mach software. Its sold by several companies- I know Harbor Freight has them in the US, and I have heard LittleMachineSHop.com will be showing them at Cabin Fever. There is also a UK seller, but I dont recall the name now. There are also many vendors of router machines.

There is also Tormach, and several others. Even Sherline has been selling one that even includes the PC.

Of course, you pay more money for these than if you built it yourself, but if you want something to plug in and make parts you can buy it.

I have to admit, for the past 2-3 years I have not built a model, just CNC machines, and I have enjoyed it, but I am now getting back to a model- and Im using the CNC machines to make parts.


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## Julian (Jan 1, 2009)

Hi Guys,

I find that the best way to learn is to do. I have converted my X1 to full cnc for the cost of three steppers and their control boards. I built the computer to run it from parts I already had in the shop. All other bits including the power supply and all wiring and fixings are bought in for very little money or built from the scrap box. My total outlay in cash passed to others for this is below £150. Mach3 is free in demo mode but there are many other progs out there for less or free.

The learning curve for this has been very very steep....you have to learn alot very quickly just to get it running and tested. Then the curve slows as you get into it. I still have much to learn but it is great fun and should be useful aswell. There is so much info available out there in books, on forums like this or just across the world on the web that there is no reason not to dabble but lets face it this comment applies to anything.

I have started with a mill and now am moving to the RT but then I have never started with the easy option!


Happy New Year

Julian.


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## ianjkirby (Jan 1, 2009)

Hi Guys,
 First up, Happy New Year to all.
 Second up, have a look at http://cncteknix.com/portal/index.php. These guys sell a 3-axis servo controller for way less than $US1000. (Its the blue thing you see when the page opens.) I have seen it in action, and it is everything they claim it to be. It is a plug and play unit, ie no soldering, or complex wiring required, other than connecting the supply, motors and encoders, all of which is covered in the included instructions.
 I have ordered a 4-axis unit, and am in the process of converting an X3 mill, and a C6 lathe. I hope to report on these machine in due course, with pics of course!
Regards, Ian.


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