Purchasing new parts for new build.

[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?

[lucan07]

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?

It did turn out a strong build and have been happy with rigidity and weight so far a few things I would change if starting again, hindsights a wonderful thing, but as I have no previous experience in any sort of metal work apart from bolting some lightweight frames together a lot of the changes would be things learned during the build.
http://www.mycncuk.com/threads/9678-...-Framed-Router

[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]

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.!!

Thanks for take time to write so much! Really appreciate your words/help.

I Already have nema 23 motors and drivers :/ im 99% sure that they support some high voltaje. I already made the mistake that purchase a lot of stuff a few years ago, will try to make it better now and follow your advices before waste more money :/

Maybe copy the design from other guys?

I really want to use some of the pieces that already have, but if not possible is OK, i want an stiff machine, dont want tooo much precision, but of course if more precise better.

[mekanik]

Samsagas
Do as instructed by jazz, take some time to read the build logs all the way through, then read them again. the forum contains priceless knowledge you just have ingest it.
Good luck
Mike

[samsagaz]

Samsagas
Do as instructed by jazz, take some time to read the build logs all the way through, then read them again. the forum contains priceless knowledge you just have ingest it.
Good luck
Mike

Ok, will try to find some good log that dont use welding :/

[samsagaz]

Guys, some log to recommend me?

As you see im looking for something useful, i was thinking abt use UPN because are not hard to find in Argentina at normal prices (i pay 18USD for 1 meter of used UPN 160mm yesterday).
Companies that cut aluminium and steel with water/plasma/laser are very expensive, but looks like i will need to pay for that service.

I get the idea of use UPN because its used in some of the vids that i post, but of course they guys have good welding equipment and mill the welded surfaces to fix deformations.

Im a little lost now... EPOXY very expensive, machining very expensive.....