[Furbi]

Hey,

Who did your stress relieving?

Also, have you given much thought to a motion controller, axis motors and motor drivers?

[Feist92]

Stress relieving was done at Heat Treatments in auckland.
Motors will most likley be nema 34 with leadshine controllers but with regards to the control board Im weighing up between EdingCNC and Kflop. Im leaning towards EdingCNC just because the interface look sreally nice and I hate the idea of using a mouse. What I dont like is how expensive it it. Im hoping Arie might chime in and convince me to get it lol. If anyone has any thoughts on either one or has an alternative Id very much like to hear it

[Furbi]

I'm making something similar at the moment, think I've almost settled on the DSPMC system at vitalsystem.com

[handlewanker]

Hi.....that's an exotic package by any stretch of the budget.

I've indulged in 3 Nema 23 425 oz/in steppers, plus one still to come for the 4th axis when it gets made, and four separate M542H stepper motor drivers with a break out board to match......powered by a yet to acquire 48 volt 600 Watt power supply, all available on EBAY......total price around $550.

I think the Nema 23 stepper at 425 oz/in will be enough to drive the table.......I won't be thinking of high rates of acceleration for a 3025 build even if the table I'm planning on making will be 40mm thick steel.

My main worry will be the milling spindle and motor.

I'm starting to think in terms of a 2.2Kw high speed air cooled spindle, but make it belt driven to a mill spindle to give a 1:4 belt driven reduction for extra torque when milling.

If it sits upside down and side by side with the mill spindle it can drive the mill spindle with a pulley at the top.

This will give the 1:4 lowest speed reduction at 2,000rpm to 6,000 rpm for milling with maximum torque.

The high speed spindle can then be reversed and fitted the normal way up to get the high speed 8,000 to 24,000 speeds for engraving and carving etc.

That is, unless a suitable motor light enough and powerful enough to drive a spindle separately is available......just a thought.

Milling is the more important feature.
Ian.

[alan_3301]

I'm starting to think in terms of a 2.2Kw high speed air cooled spindle, but make it belt driven to a mill spindle to give a 1:4 belt driven reduction for extra torque when milling.

If it sits upside down and side by side with the mill spindle it can drive the mill spindle with a pulley at the top.

This will give the 1:4 lowest speed reduction at 2,000rpm to 6,000 rpm for milling with maximum torque.

The high speed spindle can then be reversed and fitted the normal way up to get the high speed 8,000 to 24,000 speeds for engraving and carving etc.

That is, unless a suitable motor light enough and powerful enough to drive a spindle separately is available......just a thought.

Milling is the more important feature.
Ian.

Where are you going to get a 4:1 belt reduction that does 24000 rpm?
As far as I know, MXL T2.5 is the fastest, and it's good for only 20K @ 0.5 HP

GT2 3m is good for 3HP @ 10K rpm, but that doesnt do any good.

I guess you could double the max rpm and see how long it lasts?

[Furbi]

I don't think steppers would work for this build, although you can still setup a closed loop system with steppers so in that case you could make it work.

Handle what configuration is the machine your building? are you machining wood / ali, or steel to?

[handlewanker]

Hi, the build I'm currently making.....photo in earlier posts..... is specifically designed to handle steel, that is why the spindle drive is the critical part for the lower RPM range........high speed spindles don't have the torque when down at 8,000 rpm, their lowest range.

Going to engraving and carving and you can use the water cooled high speed spindle straight out of the box as you need the speed in that mode.

The main interest is to mill parts without having to be held to a time or production schedule, both of which dominate the machine's end capability in the design department.

In any serious build there are a number of criteria that must be met.........first and foremost is rigidity in the structure with second a backlash free running.......last but equally important is the work envelope which will dictate the size and layout of the main machine body.

At the moment a suitable motor to power the mill for milling steel is top of the must have list.......everything else is off the shelf commonly available items.

If weight becomes a problem in the moving parts I'll sacrifice acceleration in favour of getting it to happen.........when a CNC machine is running nobody really wants to stand and watch it do it's work for a few hours at a time, so a slowish acceleration is not a problem for me......time is not money.

The work envelope is only 300 X 250 which is almost the same as Feist92's build at 300 x 300, so acceleration is not a critical factor but having enough torque for milling forces is.....CNC is cutting with small cuts and many of them, and carbide is the only way to go.

I'm going to do some research to find out how many RPM a poly vee belt can tolerate without disintegrating prematurely.......... in that mode a toothed or timing belt is not even an option.........high speed reduction has always been a problem in the primary drive train, but if turbines can do it so can a high speed motor.
Ian.

[handlewanker]

Hi, just been doing some doodling on my graphics pad, and the prospect of QCT is easy to achieve, but at the same time an ATC is even simpler to have with the router/bridge mill type of machine.

To have a viable ATC mechanism all it takes is to have a rotary magazine to the far left of the X axis travel and to have the X axis move off the table to access the various tools with an up and down move in the Z axis.......the rotary magazine only needs to rotate for each tool selection either with a Geneva drive or a stepper motor......it will always be on the centre of the tool and only needs to be positioned laterally over the tool centre position.

This is much simpler than a column mill ATC which gets complicated to say the least.

Why an ATC for a CNC router of this small size?.........because you can do milling, drilling and tapping operations without having to be present to do constant multi tool change operations etc.

It's castles in the air at the moment, but the prospect of having it is enthralling.
Ian.

[Feist92]

Ian where did you find 40mm plate? Ive been getting quotes from all the steel supliers in NZ and they all want about $160 for 300x300x30

[handlewanker]

Hi, I first thought about a 20mm thick aluminium slab, but as it would be prone to wear etc I then went to a steel plate slab at 40mm for an original design idea, but our local guy didn't have it in stock........ but with further R&D as to the prospect of milling Tee slots in the dang thing......I've decided to do a composite build all welded together and use 3 pieces of 60mm X 40mm 500mm long hot rolled flat steel bar and two additional pieces of 40mm X 40mm square bar to make up a table 250mm wide by 500mm long and 40mm thick.......for a 300mm X 300mm table you would need four 60mm X 40mm pieces and two 40mm X 40mm pieces, all 300mm long.

As I mentioned a while back, the individual pieces can easily be milled on their sides with slots to give a Tee slot shape when placed side by side and welded along the middle of the slot top and bottom.

There's just no way that any milling forces can buckle or distort that table, or any tee bolts that hold work down.

The reason I'm going for 40mm is so that 20mm wide slots for Tee bolts and nuts can be used, and projecting the end shape of a 20mm wide Tee slot with the undercut proportions against a 40mm thick profile will give sufficient table thickness for the Y axis linear rail bearing blocks and ball nut housing to bolt up to.

I'm working on having four 20mm Tee slots.....having gone away from the plain hole or tapped hole idea when the Tee slot solution came up.

The other alternative was to buy an XY co-ordinate table......425mm X 240mm with three 12mm tee slots for about $430 from our local Hare and Forbes machinery dealer, keep the table and sell off the rest.....it's cast iron but I wanted it at 500mm long, so decided to design one with a steel composite construction.

Welding down in a 20mm wide slot is not a problem for a stick welder and the back side is a piece of cake too.

If the mass is clamped and welded progressively no distortion will occur.......with minimal machining on just the top and bottom afterwards.

BTW, $160 for that piece of 30mm plate would be much cheaper than a cast iron table, even if you contemplate milling the tee slots in the slab.
Ian.

[Furbi]

Fiest, have you tried many of the plasma/laser cutting shops around auckland? some of them may have that size in an offcut bin.

[shedbob]

Hallo Feist92.Your z-axis looks much bigger in the photos than in the drawings! Looks good.

Just to repeat those bldc links for consideration seeing Ian couldnt get them.

Brushless DC Motor, Brushless DC Motor direct from Shenzhen Hishine Energy & Electronic Technology Co., Ltd. in China (Mainland)

CNC Milling Spindle Archives - Stepper Motor | Stepper Motor Driver | CNC Router | Laser Machine | 3D Printers For Sale Stepper Motor | Stepper Motor Driver | CNC Router | Laser Machine | 3D Printers For Sale

Or search alibab for "cnc spindle motors" for other suppliers.

You could try the scrap guys for the chunk of steel.Is there any competition in NZ?

[handlewanker]

Hi, thanks shedbob........now I see it.......plenty of motors on there......they seem to be very cheap......min order qty of 1 for a price of $100. for a 2,200 watt 6,000 rpm BLDC motor and controller.

The size of the motor body is 214mm long X 123mm square and a spindle diam of 19mm.....weight 9KG.....speed range...... max 6,000 and min 400..... max torque 7 NM.....300 volts DC..... 7.3 amps.

This would seem to be an ideal solution for my build......anyone have any ideas on this motor?

With a weight of 9KG, I'll have to compare it and it's size to a 1/3 HP (350 watts?) 3 phase motor at 3,500 rpm......available locally for $59 on EBAY.....but at 2,200 watts and 6,000 rpm the BLDC motor seems to be the winner all the way

For that solution I'd drive the spindle 1:1 with a 5 rib poly vee type belt and 75mm diam pulleys.

All of a sudden the pieces fall into place, so now we have a solution.
Ian.

[handlewanker]

Hi, the second link also shows BLDC motors, but the price range starts at $500 +.....am I missing something?
Ian.

[gary_808]

Hi, the second link also shows BLDC motors, but the price range starts at $500 +.....am I missing something?
Ian.

2nd site is an actually website of a company probably get some back up.

1st site is like chinese ebay wholesale but with companies rather than individuals.

[handlewanker]

Hi, the first site offers a min order qty of 1.......that isn't wholesale, or is it just a sample for accredited wholesalers that have to be registered as such etc?......I don't think I'd want to pay $500 + just for a motor.

They also want paying with Western Union.....I normally pay whoever/wherever with Paypal.
Ian.

[gary_808]

Hi, the first site offers a min order qty of 1.......that isn't wholesale, or is it just a sample for accredited wholesalers that have to be registered as such etc?......I don't think I'd want to pay $500 + just for a motor.
Ian.

The one item you picked offers just one.

But quite alot have minium order quantities.

Don't ask a question about something then disregard the answer.

Google the website and you'll get your answer.

Only buy from trusted sellers on alibaba as well, quite a few dodgy goings on to be found with minium research.

[louieatienza]

Hi, the build I'm currently making.....photo in earlier posts..... is specifically designed to handle steel, that is why the spindle drive is the critical part for the lower RPM range........high speed spindles don't have the torque when down at 8,000 rpm, their lowest range.

Going to engraving and carving and you can use the water cooled high speed spindle straight out of the box as you need the speed in that mode.

The main interest is to mill parts without having to be held to a time or production schedule, both of which dominate the machine's end capability in the design department.

In any serious build there are a number of criteria that must be met.........first and foremost is rigidity in the structure with second a backlash free running.......last but equally important is the work envelope which will dictate the size and layout of the main machine body.

At the moment a suitable motor to power the mill for milling steel is top of the must have list.......everything else is off the shelf commonly available items.

If weight becomes a problem in the moving parts I'll sacrifice acceleration in favour of getting it to happen.........when a CNC machine is running nobody really wants to stand and watch it do it's work for a few hours at a time, so a slowish acceleration is not a problem for me......time is not money.

The work envelope is only 300 X 250 which is almost the same as Feist92's build at 300 x 300, so acceleration is not a critical factor but having enough torque for milling forces is.....CNC is cutting with small cuts and many of them, and carbide is the only way to go.

I'm going to do some research to find out how many RPM a poly vee belt can tolerate without disintegrating prematurely.......... in that mode a toothed or timing belt is not even an option.........high speed reduction has always been a problem in the primary drive train, but if turbines can do it so can a high speed motor.
Ian.

The spindle speed you really need is dependent on the size of the tooling you are using. EVEN WITH STEEL, the smaller the tool, the higher the RPM required to meet the SFM specs of the tool., otherwise you'll burn endmills out like they're out of style. So you'll need a wide range of speed, and a dual pulley system to switch speeds would be helpful.

As far as weight is concerned, you buy motors to fit the mill at hand, not build the mill to fit the motors you want to use. This is why they make them in different sizes, and ballscrews in different leads.

Acceleration is actually very important as it is related to the accuracy of your machine, especially when approaching corners, and surface finish.

You set up your parameters based on the material and the specs of your tools. Small and many cuts are a misnomer for all newbie CNC guys. as you're presenting the most inefficient part of the tool to the work, and you're creating the least ridged setup possible. You should cut as deep and fast as your machine will allow you to.

As to poly vee belts - if you're goal is ATC and you want to do any kind of synchronous CNC tapping, then you NEED either a toothed belt or direct drive for the spindle. There are actually many REAL machining centers that used toothed belt transmission for the spindle, and many of them are high speed.

Finally yes, time is not money. You can always get money back. You never, ever, get time back, wasted or not.

I don't think steppers would work for this build, although you can still setup a closed loop system with steppers so in that case you could make it work.]

The newer generation of high torque steppers can do the job well in smaller packaging than before. Check out the newer technologies from companies like Kollmorgen and Lin Engineering. I don't understand the appeal of buying dirt cheaper import steppers, with likely the worn or inaccurate dies used to stamp the laminations, lesser grade motor wire, inferior bearings, less linearity with microsteps....

[Furbi]

When it comes to machining steel/stainless, you don't think you would start missing steps? you can't just set feeds and speeds as low as you want ( as you said )

maybe it would be ok. never really considered steppers for my build. maybe i should.

[Furbi]

Try fletcher steel, i got a price of $155 for 300x400x40 (grade300) which is around $4.20/KG vs $7.60/KG (300x300x30 @ $160)