Accurate Strong Gantry

[Boyan Silyavski]

Now you have got me with that constant changing of the design. Why don't you like one design, stick to it and further develop it to suit your needs. If you liked the before suggested design from the video in post #41, then just see what is good and what could be bettered. i would suggest even contacting the guy and asking him if he were to make it again what he would change and what he liked. That will save you a lot of unnecessary trouble and give you invaluable real life feedback. Thats why people stick with certain designs, cause they are good and there is feedback.

I understand that the overhang of his design is bothering you, and it should be. Cause it bothering me. Not only the spindle, but the hole gantry overhangs. That kind of kills the good points of that particular design.

One thing from a design point of view people should understand is that the fixed gantry design we discuss here has one really strong point. I am sure most people don't understand this point properly. Its not that the gantry is fixed. Its that the rectangle it forms is very big so its moment of inertia is incredibly big. So when changing that fixed gantry design/where it forms a portal with 2 legs/ in any way that compromises it main strength is not a good idea.

Another basic point to understand is that all rests on a couple of bearing blocks in all 3 different coordinate planes. So no matter how strong you make the machine frame, the bearing spacing, placement and forces there will form the real weak spots.

the purpose of the strong frame is to hold enough for the forces. next purpose is to minimize bend and twist which leads to minimizing vibration.

What people fail to understand, i see it here and in the other forums, is that the machine frame should be sturdy to a certain point and then the aim should be to be integral. No need to make 1 ton machine when same could be achieved with integral 200kg one.

Sturdy machine that is extremely rigid will ring like crazy if not integral. So thats when all make them heavy instead of making the design integral.

By integral i mean designed so that all forces spread equally, neutralize themselves and no weak spots and overbuilds in any direction possible.


Thats why there are some principle designs that all use, cause they are integral. Not that always people take full use of the possibilities with that design.

I assure you that a properly designed L gantry will beat any day the fixed gantry design if its not properly designed.

And IMHO after playing a lot and rethinking all designs and reinventing the wheel, my conclusion is that if all things taken into account we must not forget that we usually use only 2.2 -3kw spindle, using only 6-12mm bits, so we should not forget the strongest point of each design and choose it when needed, cause at the end they will all work if made properly.