Large aluminium profile build

[Boyan Silyavski]

Hi,
Welcome! This will be one quite expensive baby.

Answers:

- the machine should be done so that will do from the beginning whatever will be meant to do. because "later" very soon becomes "never" to lack of time.

-edited: ball screw size 2010 if i was doing that

-70vdc drives for the motors, AM822 and similar digital drives

-steel is 3 times heavier and stronger than aluminum, so design accordingly. Weight is no problem for Z as far as the gantry stays below 70-80kg, 90 at the most, where you will need servos to move that mass reasonably fast
-normally Z axis travel is better achieved when rails move with plate and blocks are fixed. in that case the rails reinforce the moving plate also
if you read my first build from signature, at the end somewhere you will see a correctly made strong Z axis from steel plate and dimensiones. The type i advise, with the moving rails

-if you go with aluminum profile i believe L shape is popular because it offers better stiffness in all directions, plus some other minor benefits you will discover when designing how to mount the pieces

-design the end supports of ball screws so that they have play in all directions and are easy to adjust. bk supports are better for me, as they will not squeeze between them the ball screw

-cheapest and best brand for me VFD in EU is Toshiba, ebay Italy, inverters and motors. Chinese ones work also good.

-HTD 5M 15mm belts is best. min pulley ~20mm, has enough tooth engaged for this job, no less than 18t. calculator Avoid idlers. keep it simple.every element introduces imprecision.

-reinforcing the gantry profile with bolted steel plate at the back or across is better than filling with epoxy. could lead to need of servos though due to weight, so calculate well

-shimming seems best to me in combination with aluminum profiles. everything is possible. you could even straighten perfectly a profile using plastic hammer, DTI and 2m straight edge, if you are good with hammer like me.

-you will need that 2m straight edge, 50cm square, 30cm square, 10cm square. / read my second build log why/



That should keep you busy for a while

[Clive S]

Boyan I don't know why you always insist on rotating ball nuts for this size of machine my router is 1600 x 1000
using 1610 on X and Y
I can easily get 10m/min with 2 x nema 23s the screws don't need to be as long as the table.
Although I use two motors many people use one nema 34 with a belt connecting the screws.

-you will need that 2m straight edge, 50cm square, 30cm square, 10cm square. / read my second build log why/

Very few people have a 2 mtr straight edge and still get perfect good machines just have a look around the forum.

• iv’e seen some threads in which the Z axis was designed in a way that the bearing carriages are stationary and the rails move with the spindle - could anyone point clear this up or point me to the right thread?

One of the reasons for this, ie putting the rails on the spindle plate is that it stiffens the plate up

[Jonathan]

Boyan I don't know why you always insist on rotating ball nuts for this size of machine my router is 1600 x 1000

I can easily get 10m/min with 2 x nema 23s the screws don't need to be as long as the table.

I agree with Clive on this point. Rotating nuts only start making sense if the axis travel you want is over about 1.6m and start looking like the best option at around 2m. Otherwise they're just unnecessary complexity and will result in worse performance due to the higher inertia of the assembly.

[Boyan Silyavski]

I missed that cause he said " 3000X1500 table" so i missed that the router is quite smaller. Sorry for that. Then all else what i said stays same except ballscrew size

I never have insisted on rotating nuts for a small table less than 1.8m???

[JAZZCNC]

I missed that cause he said " 3000X1500 table" so i missed that the router is quite smaller. Sorry for that. Then all else what i said stays same except ballscrew size

I never have insisted on rotating nuts for a small table less than 1.8m???

While we don't agree on exactly whats needed for good machine I'm not so sure you need to appologise Boyan because of this statement.

I would like to be able to work with full sheet material so I’m thinking of a 1300x1500x150 format (total size not workable area)

Full sheet to me means 8 x 4(2440 x 1220) so think the OP has got his sizing mixed up.?