[rustyh]

i can tell Who has experience or just opinions ..

Haha, and I have none
Plus, I have a rigid frame and a floppy head!!

[ihavenofish]

Haha, and I have none
Plus, I have a rigid frame and a floppy head!!

TMI!!!

[manyhats2007]

You guys know that you can ignore specific users, right? If you're amused by certain individuals, more power to you.

[handlewanker]

OK, so you think you know it all........I still say that a semi rigid column has no credence when you want to mill seriously........having a heavy head casting adds no advantage when the cutter reacts with it and the column is unable to give the vital support it's supposed to be giving.

In case anyone forgets, any vibration that appears at the cutter via the column is deflection at the cutting edge.....no matter what damping methods are used the column is the vital part and all else is dependant on it.

Pity people can't pick out the parts they don't know about and gain info thereby, leaving the rest to those who need to know, whatever.

For those that dwell in the lofty heights of industrial machinery and compare them to the SVM-0 type of mills.....you're on a different planet.

.........."a heavy head on a relatively floppy column is better"????......now that is an argument I won't even bother to answer to.

No more to be said until the mill arrives and you might get a casual comment.
Ian.

[louieatienza]

Ian Ian Ian... If you're not willing to understand the Mach3 screen, how on God's green Earth do you intend to operate your CNC? Mach3 IS what runs the machine! If you don't use it, your CNC will be relegated to a doir stop. The control board is NOT compatible with other software that I know. If you think it's gibberish now, wait till you try to run a program and "debug" it. In reality Mach3 works very well, if and when you learn to weave through the myriad setrings. Skins can be downloaded that add useful features and cleaner GUI.

I actually feel bad, because I don't think others here nean harm, they're just pointing out the painfully obvious. There are many here with far more experience in CNC than you or me. I've tried to learn as much as I can here as well as all over the net, and try to give what knowledge I've attained back to the community. So when someone is so cocksure about everything, they learn nothing. Bruce Lee equates knowledge to an empty glass. If the glass is empty you can take water in. If it's full, all the water just spills out.

Just to make you realize, we're here, in a dysfunctional family way, to help you out. This hobby and community are fun, and there's a lot to learn if you let yourself.

Or maybe, the old dog can't learn new tricks...

[G59]

My professor in engineering said it best.
"From here on, now begins your journey into learning, everyday. The day you will stop learning, it will be time for you to retire"
That was 26 years ago, and I'm still learning. Yes, sometimes, from the fresh out of university graduates.
So, Ian, keep your mind alive and continue to learn. Mach3 is not for everyone, but once you learn it and it's quirks, it will most likely do everything you want it to and does it well.
Certainly, you won't learn everything about it in one day, and you most certainly will be standing in front of your machine watching what it's doing, until you become comfortable with it.
Also, like previously mentioned, virgin or 1 st time run programs, you will most likely find your hand or fingers resting on the E-Stop button, until the program has proven itself.
Even after many years of operating cnc machinery, 1st run programs get my full attention.
So be ready, grab a stool or chair and watch carefully.
Good day.

[ihavenofish]

.........."a heavy head on a relatively floppy column is better"????......now that is an argument I won't even bother to answer to.
Ian.

if you dont bother, youll not learn why it is correct.

[handlewanker]

I do bow to your superior knowledge in the sincerest way......Mach3 is something I'll have to learn I know.....at the moment it's like reading a telephone book in Chinese characters.....LOL.

CNC will no doubt be a very swift awakening to a new world once the first step is accomplished.......that first step could be as little as switching it on, opening the door etc.

What happens next is anybody's guess, not having the faintest clue on how to make it respond to anything and having to guess what G code means right from the beginning.

Like I said, being a visual person I see things clearly when I see them in a real world context.........if I can find an app for the IPAD like say SimCNC Milling Machine etc, or something of that nature, the door will open and the screen mill will move and if it crashes so I will learn time and time again until I get it right.....pixels come to no harm when they disintegrate....LOL.

What is needed is a simple CNC job layout with some milling features on it such as a 100mm square plate, mounted in the vice, with a 25mm hole in the middle and four 6mm holes in the corners, and also the G code progression from the very first move that will allow me to see the steps that it takes in mach3 to actually start the mill and move the various axes and when to change tools from drills to end mills etc......the whole shebang in step order.

I'd like to be able to do something like that on a simulation and watch the mill perform as it's directed......once I get to know what G something does all will become clear.

I've seen some demos where the demo person moved a dot around the screen along the tool paths, but it was totally meaningless as it wasn't "real", or simulated real.

BUT........it won't happen today and it won't happen tomorrow, but it WILL happen.

When Defeng delivers the fun begins.
Ian.

[G59]

Ian, read and learn gcode.
You are going to need to even if you have a cam program that does that for you.
Why? So you can understand what's going on if something goes wrong. Also you'll be able to use the teach feature included in mach3, to directly input code in it without the need for cam software.

Simulation is good, but knowing what's going on and mentally visualizing it is even better.
Plus you'll learn tool offsets and everything else before you get your machine.

Being that you are starting fresh, a little patience will go a long way.
If your rush through things, you will guaranteed, have many crashes, some that could possibly be expensive to repair.

[jips]

I'm visual too but you have to take it by the right way theory have to be learn before anything
More over it's a part of security to know by heart your machine and that include the software ! Think about the machine is unclosed !
As a lathe machinist i have seen people losing finger , badly injured , and one died ! When we tell you that you will have your heart beating and your hand near shaking above the Estop that's true but this really became true when you have encountered a crash , there is lot of crash story and you can ask to any machinist each one 100% will answer a crash or problem that can be take his life . Machining as hobby is even more dangerous than you are alone on your shop you CANT take risk . But all i said will certainly more talk to you when you'll see it by your eyes with a bit of endmill broke and fly on your concrete like a bullet or 1000 story like this that will make you feel that your machine is a wild horse that you need to know and understand a pilot take hours and hours in learning before fly in real

[G59]

We'll said jips

[louieatienza]

Ian, there are CAM software available with full machine simulation. The rub there is, if you don't have a CAD model of your machine, and some more pricey CAM, you won't see what you're referring to. Even rudimentary CAM like Cut2D will model the tool and stock removal so you have a good idea what's going on. You can play with it and see... Really the full machine simulation is most beneficial for 4- and 5-axis work where collision checking is harder to visualize with standard simulation.

The job sample you mention can be easily done with Cut2D, or even Mach3's own DXF to g-code converter (though I think Cut2D makes it so easy even I figured it out after 5 minutes without reading the manual.) You SHOULD make this happen today. It's the one thing you CAN DO RIGHT NOW, that will get you so far ahead when the time comes. All the other stuff is meaningless if you can't get a grasp of the basic operations of Mach3.

- - - Updated - - -

We'll said jips

Aye! +!

[Skyfire]

Thanks a lot guys. Very appreciate. And, thank you Ian, finally I realized my body is not that yang any more..just so happy to get back to work and my current top object is to finish your guy's machine and send out one by one. That will give me some relief.

I'm working on many items now and I found many subjects in my thread I need to catch up.. I will review and posts my answers to your great discussions one by one. So glad to have many great engineers here. We may have different views and maybe our knowledge is limited. But the truth is out there and discuss will always lead us to it...at least near it.

One of the latest topics looks like to be the gas spring. Firstly, add this part doesn't means the Z motor is not powerful enough to drive the machine head weight--it's more than enough. An important reason is as Louie said, to prevent head drop when power off. If the linear rails and ballscrew are installed good enough(straightness and parallelism), there is a big chance that the static friction can't hold the head and it will fall. So the gas spring can balance the weight and keep the head at where it should be.

Another important reason is something about the acceleration too. Without the spring, when Z axis acceleration direction is downward, it's totally ok. but when it's upward, it may cause lose step if the acceleration is a little big. So, balancing the head weight with a gas spring equal to cut it's inertia and make Z axis more "sensitive".

And a quite important reason of balancing the head weight is reducing the load of bearings(including the ballscrew shaft bearings and balls in the nuts) when acceleration. Bearing load may get too big without head balancing. It will make the balls wear out quickly and then losing accuracy. Bearing load is actually quite big when accelerating suddenly. I can even observe smoke comes out from bearings when I test high acceleration. Our shaft bearings are all of grease lubrication and this will happen worse than oil lubrication.

But, on the other hand, gas spring has damping effect too. If Z axis acceleration is too big, it will not help but make it even worse. But,,in our acceleration and speed range it shows to be no problem after my many tests. So..in a word, truth has its limits. For SVM, gas spring shows to be good.

Thanks everyone.

Defeng

[louieatienza]

Thanks Defeng for a great explanation!

[G59]

???????
Everything is so much clearer now.

Good day.

[handlewanker]

Hi D......thanks for the heads up on the gas strut operation.......I've always felt that when you have any load that is off balance you need to compensate for it.....my way of thinking coming from a horizontal borer working background.

As an extra observation, if the gas strut was purely for preventing the head self winding down due to gravity, then a solenoid brake would be the answer,

When I worked on the mines in Namibia, all the conveyor belts had hold back solenoid brakes fitted to prevent the belts, which carry hundreds of tons of gravel at any one time, from back driving the worm drive gearboxes and dumping the gravel load back at the pick up point.

We also had static centrifugal braking that held the gearbox drive stationary when the power was cut and released once the drive was activated.

But.......the gas strut does have a double purpose, and in my opinion the balancing of the heavy head is of the most importance and the prevention of back sliding "may" be a second consideration too......it could probably be of more importance than I realise if/when the power is off and the head slips down.

Defeng, as we have patiently waited with great anticipation for the mills to arrive, I think we can be patient for a bit longer to enable you to not stress yourself to the point of nervous exhaustion and detrimental work loading.

All we ask is that you do a great job to make this project a byword for innovation and uniqueness as there is nothing quite like it on the CNC market.......and the price is cool too....LOL.

I think the SVM-0 is now as fully developed to a point and as far as you'd want to go with a CNC mill in it's class, and any further modifications would just complicate production without any real gain.

As a matter of interest, is the basic SVM-0 going to be a standard catalogue stock item with the ER32 spindle only and without the split head casting, or will it only be offered as a special order model like the one I ordered with multi spindle choices and as a special order at customer cost etc?

If the options for versatility are to be catered for, I think a split head casting is the only item that needs to be stocked as all the other bits can be bought off the shelf, provided your spindle manufacturer also stocks or can provide the modified ISO 20 spindles with 80mm bodies etc.
Ian.

[louieatienza]

Hi D......thanks for the heads up on the gas strut operation.......I've always felt that when you have any load that is off balance you need to compensate for it.....my way of thinking coming from a horizontal borer working background.

As an extra observation, if the gas strut was purely for preventing the head self winding down due to gravity, then a solenoid brake would be the answer,

When I worked on the mines in Namibia, all the conveyor belts had hold back solenoid brakes fitted to prevent the belts, which carry hundreds of tons of gravel at any one time, from back driving the worm drive gearboxes and dumping the gravel load back at the pick up point.

We also had static centrifugal braking that held the gearbox drive stationary when the power was cut and released once the drive was activated.

But.......the gas strut does have a double purpose, and in my opinion the balancing of the heavy head is of the most importance and the prevention of back sliding "may" be a second consideration too......it could probably be of more importance than I realise if/when the power is off and the head slips down.

Defeng, as we have patiently waited with great anticipation for the mills to arrive, I think we can be patient for a bit longer to enable you to not stress yourself to the point of nervous exhaustion and detrimental work loading.

All we ask is that you do a great job to make this project a byword for innovation and uniqueness as there is nothing quite like it on the CNC market.......and the price is cool too....LOL.

I think the SVM-0 is now as fully developed to a point and as far as you'd want to go with a CNC mill in it's class, and any further modifications would just complicate production without any real gain.

As a matter of interest, is the basic SVM-0 going to be a standard catalogue stock item with the ER32 spindle only and without the split head casting, or will it only be offered as a special order model like the one I ordered with multi spindle choices and as a special order at customer cost etc?

If the options for versatility are to be catered for, I think a split head casting is the only item that needs to be stocked as all the other bits can be bought off the shelf, provided your spindle manufacturer also stocks or can provide the modified ISO 20 spindles with 80mm bodies etc.
Ian.

They make electric brakes for steppers/servos . The problem is, gas strut = under $20, electric brake = over $200....

You can lift probably twice the head weight with this set-up, in fact if you pushed down with all your might on that head while it moves up slowly, I bet you would be hard pressed to stall the stepper. I've snapped a couple endmills just carelessly rapiding into a vise on my CNC router, and my machine has nowhere near the mechanical advantage of this screw/motor combination. In short, the stepper/screw combination is more than adequate at overcoming any imbalance. Component longevity trumps that.

With your aforementioned job example this is not really as much an issue since the Z remains static during each cut level. Where you'll see the most benefit is when 3D contouring, particularly high detail surfaces, sharp corners. Lower accel can cause some "smoothing" due to the way CV works in Mach3. However I've found this can be taken advantage of with smoother contours as it can help with the "faceting" that can occur, primarily due to the way most 3D CAM interpolates 3D surfaces.

Yes having the option of easily changeable spindles is appealing, when my need for one comes.

[inov8r]

Defeng,in keeping with the original post "Show how to build a CNC machine from the very beginning to the end" I would love to see some pictures of your operation rising from the ashes!

[ihavenofish]

steppers have a detent torque that will generally prevent the head from dropping when not powered unless its extremely heavy. servos require a brake.

for example, my novakon head will drop when no motor is attached, but when the stepper is attached, it wont drop.

the gas strut will hold it up too, but as i have said it isnt mandatory.

[louieatienza]

steppers have a detent torque that will generally prevent the head from dropping when not powered unless its extremely heavy. servos require a brake.

for example, my novakon head will drop when no motor is attached, but when the stepper is attached, it wont drop.

the gas strut will hold it up too, but as i have said it isnt mandatory.

I believe though the Novakon has Nema34 steppers, likely higher detent torque than the NEMA23 steppers on this machine. Sure the weight on the Novakon head is likely higher as well, but also the Z axis has dovetail ways which does not have as low a CoE as linear bearings. It's nice to have a good safety feature that doesn't hurt performance! Also some "microstep friendly" steppers are designed with lower detent torque for smoother microstep movement.

I use 8-start leadscrews on my router table with AB nuts, and even with the 25lb Z carriage (not including the air chiller I sometimes use) and 425in-oz steppers and 48V, linear bearings, I do not use or need a brake, and I haven't lost steps.