I want to build this kind of machine ---->

[eranglr]

YouTube - DATRON Hochgeschwindigkeitsbearbeitung von Aluminium.
This cnc will be used for industrial design students.

The size of the table should be (aprox): 100x70x15 cm
Cut matirials: wood, aluminium and (I wish) metal

Do you have an idea about open-source plans?

I have access to a laser/water-jet cnc cutter, so if there plans on files I can just cut them out and assamble the rails/ballscrew/electronics.

Thanks
Eran

[Jason3]

My daughter and I watched the video - she said 'that's daddy's machine!'

I'll be building a machine similar to the Datron's soon - it'll be on my website Here when I start building. Have you seen the other Datron videos?

YouTube - DATRON CNC Machines

YouTube - DATRON CNC Machines

This one gives a good look at the machine doing a variety of work. Also lots of information on the Datron website too.

Should be a fun project

Best regards,

Jason

[eranglr]

Please tell me - how are you going to build this kind of cnc?
What rails/ballskrew are you using, what steppers/controller are you using?

It would be fantastic if one could send his machine specs so I coul'd "copy-paste" his specs..
Thanks
Eran

[Jason3]

Hi Eran,

I haven't finalized the design yet, and the final spec will be heavily influenced by parts I already have. My plan so far is for the X axis to use twin ball screws, most likely 16 mm dia. and 10 mm pitch, and some THK linear rails. The Y axis will use either a <a href="http://www.boschrexroth.com/country_units/america/united_states/en/products/brl/product_overview1/linear_motion_systems/ckk/index.jsp" target="_blank">Bosch Rexroth</a> actuator or a single THK HRW50 linear rail with one bearing block and another 16mm dia. x 10 mm pitch ball screw. The Z axis will use a THK HRW35 linear rail and two bearing blocks, and a 16 mm dia. x 2.5 mm pitch ball screw.

For the base I'm considering a 30" x 40" granite surface plate, or perhaps a big aluminium plate on a fabricated box section base which I would mill flat last, using the machine itself. Power will be from Granite Devices VSD-E drives running brushless servo motors, and I will use a Smooth stepper USB interface board to allow decent feed rates with the servo encoders. The spindle will initially be a KaVo 4061 1.2 Kw, 50,000 rpm HF unit, and workholding will be a vacuum system.

I'll be making the various other parts on a knee mill, and using my small CNC mill. The side plates for the gantry will probably use 25mm aluminium plate, and the other parts will be aluminium stock as necessary. I anticipate travels will be similar to yours, X = 750 mm, Y = 1000 mm and Z = ~170 mm. Clearance under the gantry will be 200 mm minimum to allow extra height for the vacuum workholding system.

All subject to change of course, this is in the early planning stage for me Usually I would fabricate the whole machine, but I'd like an easy build this time so I'm thinking of using parts that come already assembled, like that Bosch actuator and the granite surface plate, and just matching them up and fitting them together!

Best regards,

Jason

[veteq]

That are nice units heheheh,

you cann make it yourself, but it will cost money:

at least 10.000 euro when using new parts and go high speed/quality

Mach 3 for software controller http://www.machsupport.com/ 100 euro
smoothstepper card http://www.warp9td.com/ 100 euro
4 granite servo drives http://www.granitedevices.fi/ 660 euro
4 granite servo motors http://www.granitedevices.fi/ 420 euro
4 15/5 c3 preloaded ballscrews http://www.misumi-europe.com2000 euro
4 bearing blocks fixed/lose http://www.misumi-europe.com 400 euro
3 axis rail and carriage http://www.misumi-europe.com 900 euro
jaeger chopper spindle 80mm http://www.alfredjaeger.de 4000 euro
steel parts that are cnc milled any cnc milling shop. at least 2500 euro

And offcourse all the products i forgotten to mention, also there are a lot off calculations to make, it cann be done for less.

You should go wirh stepper motors instead off bldc servo`s, you cann use c5 precision rolled ballscrews and linear guides from Hiwin.com and use a chinese watercooled router from kelinginc.com.

But with the cheaper unit dont aspect to get near any speeds and precision off the expensive DIY.

This is my smaller unit thats on the way, same concept as the datron
(a little bit), use small endmills with little material removal per pass.
Precise but alittle slower machine, costs are min. 4500 euro, with a lot off ebay searching and using the fact that student are not rich (good deals for machining, LOL) xyz movement is 160/110mm/110mm, hope to get 0,01 machine accuracy

Regards,

Roy B.

Have you seen www.zealcnc.com by the way.
and http://www.5bears.com/cnc.htm

[Mike Everman]

Your work is so nice, Roy.

[veteq]

Originally Posted by Mike Everman Your work is so nice, Roy.

Hee Mike,

I take that as a big compliment coming from you,
Really like youre designs, that servonut and belt assembly are briljant!!!

Looked at the video`s maybe a 100 times, thinking, men thats good. Weeks has gone by thinking and dreaming how i could make it and implement it in my designs, than i figured it out and looked at my wallet, hmmm , damm. (LOL)

You got a nice company!

Got a question that i think you cann answer.
i calculated a lot off the aspects off my machine, about the power needed for speed and acceleration i dont now if i forgot something.

Imagine:

i want a maximum speed for an axis, i know the max. acceleration i want,
i know the mass off the table, so , (F = m * a)
i can calculate the force needed for linear acceleration and cann convert it through the ballscrew to torque at the stepper.

Then i know the inertia off the screw, coupling and stepper, i know the angular acceleration (from linear to angular, lead factor ballscrew)
So, torque for rotation cann be calculated at stepper (T = J * alpha)

This two i can count together and call it stepper almost total torque.

Then i know the break away torque needed for the preloaded bearing block and preloaded ballscrew and the maximum force, so, torque for milling through material.

At last the friction off the linear guides, almost zero.

Then i count those all together and now i cann choose a stepper motor.

Do i forgot something????

Kind regards,

Roy B.

[Mike Everman]

Thanks Roy!
That's a good start, if you have a reduction before the screw, then it's a bit better to use the reflected inertia of the payload, rather than simple f=ma. Reflected inertia is 1/ratio^2, so if your ratio is 2:1, the inertia of your table (and screw) are 1/4 the value you'd think. With fine screws, it's more about friction torque and rpm determining the continuous needs of the motor, since your force capability is through the roof for acceleration.

I've not done much in the way of allowing for cutting forces, myself, but that's coming up. I'm building a ServoBelt router, 800x800mm travel right now. I got one of those 2.2kw ER-20 spindles from Keling, a VFD from Allen-Bradley, a deskcnc card and software... let's see, Teknic 1500W servoamps, 500oz-in NEMA34 Servos, with 20Kcpr encoders.

[veteq]

Hee Mike,

for the calculation of tangial force, torque and power in relation to milling you have to buy this book:

Amazon.com: Engineering Formulas for Metalcutting: Edmund Isakov: Books

Amazon.com: Engineering Formulas for Metalcutting: Edmund Isakov: Books

It`s easy and clear with examples.

So, i=2 says the total inertia is motorinertia + (inertia screw/ 2^2).
But then i dont understand how to use table inertia??? (linear) to rotation.
That`s the f=m*a part to T=J*alpha.

So i dont have a gearbox, then i can say F=m*a + T=J*alpha

regards,

Roy

[Mike Everman]

Originally Posted by veteq So i dont have a gearbox, then i can say F=m*a + T=J*alpha

Yep, in absence of a reduction it is certainly that, with efficiency factors applied.

Thanks, I'll check that book.

[Jason3]

Mike,

Do you have any pictures you can show us of your upcoming router? You must be looking at some impressive feed rates, judging by the hardware you mentioned

I'm really impressed by your Servobelt system - did you get around to testing the stiffness yet by any chance?

Best regards,

Jason

[veteq]

Originally Posted by Mike Everman Yep, in absence of a reduction it is certainly that, with efficiency factors applied.

Than i did the calculations with friction and a FOS of 1.5
results: a nema 17 stepper will accelerate my mill with 1G till
1500mm/min.

YEAHHHHH!!!!!!

( 1G ????,......... thats a Sodick with linear motors, only no speed of 35560mm/min)