Purchasing new parts for new build.

[Norgmonster]

For my 4' x 8' table I'm planing to use Nema 34 motors with around 12Nm for the x and y axis. Is it overkill to use the same for the Z axis (planing for any future upgrades) or should i go for a nema 23 with around 4Nm?

The motors will be driven by rack and pinion.

What would be the best digital stepper drivers, breakout board and power supplies?

[Clive S]

For my 4' x 8' table I'm planing to use Nema 34 motors with around 12Nm for the x and y axis. Is it overkill to use the same for the Z axis (planing for any future upgrades) or should i go for a nema 23 with around 4Nm?

The motors will be driven by rack and pinion.

What would be the best digital stepper drivers, breakout board and power supplies?

Hi and welcome to the forum. First it might be better to start your own thread and then all the questions will be together. I have seen the vid link you posted and although the machine looks nice it won't be that accurate the gantry is too high and the feed rate looks very slow for cutting MDF. Have a read through some of the build logs. and decide what you want to use the machine for.

Don't buy any stuff until you have it drawn up in cad and are happy with the design. An 8 x 4 machine not designed correctly is a bit like digging a big hole in the workshop floor and filling it with hard earned dosh.

Good luck with the build.

[Norgmonster]

Hi Clive S,

Thanks for replying. I can start my own thread but i thought this was a general thread for people asking about parts.

I know the gantry on that design is to high and i have already dismissed most of it. The guy in the video was living my dream and that's why i liked it :-).

I plan to use proper HGR25 Rails and carriages and the gantry will be much closer but I need the z axis to have about 200mm of travel.

I hope to cut wood, plastics polystyrene, sheet metal.

As I'm designing I also want to work out a shopping list and prices so i know what i can afford.

Any advice on hardware like drivers would be appreciated.

[mekanik]

Samsagas/Norgmaster
Hi Guys
If you both get a design drawn up you will get a more meaningful response to your questions.
Norgmaster
You need to start your own thread.
Regards
Mike

[samsagaz]

Samsagas/Norgmaster
Hi Guys
If you both get a design drawn up you will get a more meaningful response to your questions.
Norgmaster
You need to start your own thread.
Regards
Mike

Well my first idea was something like this for Y fixed gantry...



i can reinforce the tower welding a plate in diagonal and can reinforce the back of the UPN too welding it too.

if close the structure can fill with sand or similar to get more weight.

i dont want high Z Axis, think that 70-80mm travel will be enough.

Its my old Z Axis idea, i want to avoid welding the parts and use an UPN as show in first image



Sorry for my english

[Clive S]

My first observation is that you have to be able to build it and assemble the parts have you thought how you would bolt the bearing blocks to the z plate (I think the blocks are to close together). This is why you should draw it out to see these problems.

[lucan07]

With a short a travel required on the Z axis I followed some advice on here and virtually did away with the gantry sides and mounted rails on top of a pair of 6x2" box sections which resulted in a very solid gantry with little effort.
http://www.mycncuk.com/attachment.ph...7&d=1461873328

[samsagaz]

With a short a travel required on the Z axis I followed some advice on here and virtually did away with the gantry sides and mounted rails on top of a pair of 6x2" box sections which resulted in a very solid gantry with little effort.
http://www.mycncuk.com/attachment.ph...7&d=1461873328

ok, will check that.. i was drawing while you post that :)

Its your machine? Looks an strong and nice design because dont weld anyhing, wich is the post? is your machine?

[JAZZCNC]

Samgaz:

Channel isn't very stiff and certainly not flat. Welding in braces etc will cause heat and twist etc. So unless you intend machining the Gantry flat and true then I'd suggets you look at better materials that won't need stiffening by welding.

Your Z axis idea with Channel is disaster waiting to bite you. Like Clive mentions the practical side of bolting etc means it won't work but again Channel just isn't flat enough or good enough. Z axis IS THE MOST IMPORTANT part of the machine.

25mm ballscrews are too large for machine this size and will actually lower the performance and increase the costs in ways you haven't realised yet.
The extra interia of the Screw and Ballnut means you'll need motors with higher torque. This will mean using Nema 34 Motors.
Nema 34 motors spin much slower than smaller nema 23 motors for the same amount of voltage. So this means you need higher voltage to get the same or similar RPM.
In practise this means using drives which offer much higher voltage capabilty. While 60-70Vdc will be fine for nema 23 it will cripple performance of nema 34 and the Larger the motor size the worse it will get. So often larger Nema 34 Motors use drives that run at mains voltage levels.

If you try to run tham at same voltage would nema 23 then your RPM will be so slow the machine is crippled.

NorgMonster: This also applies to you and it's the only comment for you I'm making on this thread so start your own if haven't already.

It's common mistake that Bigger is better and offers upgradabilty. It DOESNT. What it does is Cost more and lowers performance.
Nema 23 motor matched with correct size and Pitch ballscrew run with correct voltage on decent quality drive will run rings around and cost much less than Nema 34 motor running on wrong voltage and connected to large ballscrew.

In your case Norgmonster with R&P then you'll probably need nema 34 motors because of the much lower efficiency of R&P. But again if you don't correctly size and match components then peformance will suffer and money will be wasted.
R&P machine requires careful thought towards pinion size and Reduction ratio used along with Motor/Drive/voltage selection.

Both of you are going about this all wrong and you will Both end up wasting money, time and probably resutling in less than great machine unless you STOP buying without knowing what's required and Design the machine before starting. Fag packet drawings while ok for some things just make this CNC building a disater waiting to happen unless you have plenty of experience which you two clearly don't.!!

Stop, take Step back look and learn then design. Then look again before buying any thing.!! . . . If in doubt ask.!!

[samsagaz]

updated Z Axis