Initial design advise wanted

[Clive S]

Ok.. so i did some calculations.
Based on my original design the total moving gantry weight is +/- 65kg
~32kg z
~65kg z+y
Aditional bracing would add some 35kg.
Can this still be run on twin nema 23 / 3.1 nm gearing 1:2/ 1610 screws (y)

These numbers are a bit overwhelming to be honest. ..

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I am pretty sure they can do you have a drawing you can put up.

[driftspin]

Hmmm initial design is in post 1

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[JAZZCNC]

Can this still be run on twin nema 23 / 3.1 nm gearing 1:2/ 1610 screws (y)

Yes it will be fine. Your good to around 90Kg

[Boyan Silyavski]

You mean additional bracing will add 35kg to the 65kg? It will become a bit heavy for steppers then. Problem starts that it's ok for steppers at 1:2, but steppers are not like servos to spin reliably at 3000rpm or even 1000. So i think then it could be better to use bigger motors/ that will need bigger and much higher voltage drives /


Then just brace with 1 plate on the 80mm side from bottom of the gantry beam. That should be enough. You keep the weight right, also the rails themselves when bolted on are very strong. As bend from forward backward movement could be the biggest eventual problem and that will prevent it . You could always bolt sth at the back later if needed.

Or just don't brace at all, i like a bit OTT so you may not listen to me. When build my first machine and my current one, at the end i decided to make everything strong as i think it must be and then think how i will move it.

Have you thought for servos? I assure you i will never go back to steppers again. I could point you to servos that will not break the bank, still untested though by me. Direct from manufacturer. I think they must work well. Around 600$ 4 x AC servos with drives, you have to add transformer and make PSU for 100$ more.

Steppers will be half the price though and work fine more or less up to normal 5-8k mm/min feeds depending on screws and other details. Servos 1:1 could move up to 30k mm/min, which is ultra nice. BUt at the end i moved my machine today for first time with 16k mm/min, so all depends on what your final purpose is.

So to simplify, or stick with your initial plan, or build as you like and go with servos.

[Clive S]

Hmmm initial design is in post 1

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Yes but is that the design with the extra bracing you want to put on?

[driftspin]

Well the extra bracing will add 35 kg to 65 kg...

Boyan suggest this for the purpose of anti ringing while cutting metal

At first i thought a heavier profile would do the same but not sure now...

Stuf to think about...

Not sure if i am ready for the extra cost involved for servos.. which i am sure are nice for high acceleration and heavy gantry




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[driftspin]

Yes but is that the design with the extra bracing you want to put on?

Clive eh no, the initial gantry design is 65 KG with no extra bracing (80x120x4). The profile used is 940mm between the linear blocks.




The profiles on the gantrysides will have inserts so the m5 bolts can still be reached but sides ways flex is stopped.

Maybe i need to brace the Z slide on the sides ... aluminum can be flexi i heard.


What i am thinking about is maybe step up the gantrybeam to 120x100(or120x120)x5mm .... the linear rail wil be mounted close to the edge of the profile, for maximum stifness.
It will also generate some extra space for cable management, i have to look in to that too for the long axis also.








Some diagonals in the legs. maybe panel icw kabinets.. to be determined.
Filling the Highlighted parts with sand may do some good anti vibration and ringing?

[driftspin]

Electronics ... headache, questions...

Steering in the direction of 65volt dc PSU, 80volt drives 500 Watts or so will do....
And will keep me on track building a reliable machine...

But....
I dont want to go OTT, but dont want to under engineer either.

So after reading a lot of stuff i still can`t decide what voltage PSU/Drivers i would need to run my machine well.
Online-electronics-kits all list 36volt-PSU and 50volt dirers, that is confusing.

So here are a few questions.

The best guestimate i have for the total moving weight of the gantry is about 65-70KG
(including steppers, rail+blocks z axis 2.2kw spindle, steel, alu plate etc)

The best guestimate i have for the total moving weight Y+Z = +/-35 Kg.

The best guestimate i have for the total moving weight Z = +/-20 Kg.

X/Y 2:1 stepper : 1610 Ballscrew
Z 1:1 stepper 1605 Ballscrew

Main questions:
Q Y-axis: 2X slaved Nema 23 3nm 4Amp should be good, or OTT for my guestimated weight?!? 65-70KG
Q X-axis 1X Nema 23 3nm 4Amp should be good, or OTT for my guestimated weight?!? 35 Kg.
Q Z-axis 1X Nema 23 3nm 4Amp should be good, or OTT for my guestimated weight?!? 20 Kg.

Q What is the real advantage of a DIY Toroidal PSU, just noise?
Q What DC PSU voltage should i be running?
Q Stepperdrivers, Leadshine? 50-80Volts?

Q 1 or more PSU`s?
If 2 PSU`s. what setup, like X and Z on 1 PSU,
and the slaved-X set on 1 PSU? Or mix it up?

I think for now my initial PC setup would look like this for now.

- Dedicated networked windows 7 PC.
- Mach 3/4 through PP.
Q 64Bit or 32Bit?
Q PCI or mainboard PP`s?
Q PCI PP, what to look for when buying one.
Q Any Minimum video card requirements?
Q Maximum length PP cable to BOB.


Thanks in advance, Bert

[njhussey]

What works well, and is proven, for this size setup is 80V drivers, 3Nm steppers coupled with a diy torroidal psu that gives 60V - 72V after rectification. Advantage of the diy transformer is you can make it for the exact voltage you want, it gives smooth power and the capacitors absorb and back emf from the steppers on deceleration.

You will need 2 psu's one for the stepper drivers and one for your bob, home & limit switches, relays etc.

These days I'd be more inclined to ditch the pp and go USB or ethernet, more reliable.

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[Clive S]

I think for now my initial PC setup would look like this for now.

- Dedicated networked windows 7 PC.
- Mach 3/4 through PP.
Q 64Bit or 32Bit?
Q PCI or mainboard PP`s?
Q PCI PP, what to look for when buying one.
Q Any Minimum video card requirements?
Q Maximum length PP cable to BOB.

Bert From what I understand is that the pp does not work with win7 64bit.
For the system you are building you need a motion controller not via the pp. there are various ways of doing this.

Plus one with Neil on the power supplies. use 24V for the estop, limits etc .

Have you decided on whether to run one nema 34 with a belt between the two motors or 2 nema 23 and slaving them there are cons and pro between the two systems I use slaved I think Neil uses one motor.