Stell frame cnc 1500X1000. Adjustable table your opinion please

To be honset i think the green plates are a little bit wrong
I must correct the design. I am thinking of make the green plates square and connect the ball nut on the external red aluminium plate that will be designed longer. I dont know if i am understood, so i will design and come back later. Eddycurrent thanks for your answer.

Yes I see what you mean, the red plate must come below the level of the rails to both protect the ball screw and also to allow mounting of the ball screw to the outside of the top beam.
But will there be enough room between the extended red plate and the beam to fit the ball screw in. ?

If you see photo number 13 you will see how much space there is. This space isnt enough to match the ball screw between the plate and the 80X80 box beam. So i could even make the gantry a little bit wider or match the ballscrew at the outer side of the red aluminium plate. My first thougth was to put the X axis ballscrews at the same vertical plane as the profiled rails of x axis. In that case the x axis ballscews would cross the back plate of the aluminium construction that i use to attach the steal beams with the profiled rails. I dont know if this is a good idea as in this case i will have the x and y axi ballscrews been corsed very close each other.

I'd extend the outside gantry plate below the X axis carriages and have the ballnut housing attach to this. You might need to put spacers on the frame for the BK/BF ball screw ends but it shouldn't matter. I've done just this with my design. which you and see here...http://www.mycncuk.com/forums/gantry...planes-12.html that way you can mount the x axis carriages on the bottom 20mm ali plate and not have to bother with the green plates?

Attachment 11497

Some small changes
Attachment 11508

Attachment 11509

Attachment 11510
The green plate(20mm aluminium plate ) will be bolted on the carriages and then i will bolt the green plate with the red plate (20mm aluminium plate)
Could anybody told me what are the critical spots that i must have freedom to adjust. I think is obvious that the spindle should be vertical with the cutting surface. Is this possible to achieved by putting shims between the red and the green aluminium plate.

Vagelis can you show an exploded view or See thru view so that can see how Steel fastens etc. This seems a very complex arrangment of plates that may not be required or adding a lot to overall strength.? The design is correct regards gantry sides Etc just looks more complicated than it needs to be.

I'm also curious to how your arranging the ballscrew/motors because it looks like the steel supports across gantry could clash with ballnut.?

If you prefer Email me Model.

Dean the steel supports are from 120X60 steel tube so they leave 60mm space for the ballnut. I dont know if this is enough but even if it isnot i could make the steel supports from 40X80 tube so 80mm would be the space for the ballnut. Regards how steel fastens i explain. The 120X60 beams will be fist welded like that

Attachment 11537


Then the red assembly (made from 20mm aluminium) will be bolted with the tubes like that
Attachment 11538 Attachment 11539
I dont know if the following picture will help you
Attachment 11540

Anyway i have sent you the model did you get it

Thank for your time

Gantry looking a bit similar to this; but stronger, maybe there's something here for ideas ?
http://www.mycncuk.com/forums/gantry...html#post49880

I believe that this mixing things will not greatly benefit you.

The real things that should be considered are: precision, strength/bend twist/, weight , ball screw length, price.

What i mean is the aluminum will raise the price, lead to lower precision and a lot of hassle in combination with the steel profiles, and possibly raise even the weight. What you will gain is beauty.

I dont know what precision you aim for, but any imprecision in the aluminum will transfer to loss of precision and need to adjust.

So from my limited understanding, either use steel and epoxy or use precisely machined aluminum for all the gantry, like Dean makes his ones.

Aluminum will not magically solve rails alignment as it seems you believe, unless you buy specially intended /$$$/ and precisely machined /$$$ or ability to do it/ .

Combining it with steel will lead to shimming, what you on the first place seem to try to avoid.

If you decide on the steel only machine, i can even help you and arrange all parts laser cut in Bulgaria for cheap, so you can drive 200km and get them, assuming you live in Greece and not very far away. I mean all parts on the machine, like i did from 10mm steel sheet. That can give you immense freedom with the design and extreme ease of assembly. Not to speak of avoiding hours and hours drilling precise holes.

Just for some ideas, you could take a look at my second build. i believe the design of my big machine gantry is even better, avoiding the laser cut parts and aluminum parts as much as possible. And frankly i have not seen a DIY gantry with less overhang. See post 34. You can ignore the extreme Z as there will be 12kg spindle or pneumatic hammer, but take a look how the motor fits, how the gantry sides are avoided to be expensive and heavy. How easy will be to epoxy level the gantry rails as they are in one plane but at the same time there is no overhang at all.

Syliavski thanks for your reply
I am a little bit confused about what materials is should choose for my gantry. Firstly I was planning to make a steel gantry. 120X60 tubes for the gantry welded together lke this
Attachment 11561


Then the sides would be 10mm steel laser cutted.

Attachment 11562
I would even put the green aluminium plate at the front of the gantry, or i would epoxy level the tubes surface so that the rail would be on the same plane.
After that came Dean who adviced me not to have a fully welded gantry so i would be able to adjust. In fact at the above plans i was planning to bolt the sides with the 120X60 beams. Also i was planning to epoxy level tha base plates of the gantry or use shims in order to adjust.
After Deans comments i come up with these plan

Attachment 11563Attachment 11564
with the grey color represent steel and the red color aluminium.
I am really confused about what is better or not. I am starting to make a plan and as i have no experience about the difficulties that i will come up with, i dont know if i am right or if am wrong
So far thanks everybody for your help.

Vagelis