Stell frame cnc 1500X1000. Adjustable table your opinion please

[Boyan Silyavski]

Deans design is very good, after all he is far more experienced at building and dealing with vibrations. I like the Z at the baze, that would definitely help with resonance. I like the extra bed frame, i have thought it but never included it in my designs, due to extra weight.


Dont get me wrong on what i will say, but i am fan of simplicity. I will say the same what i said to Tony at his thread

Look at that design below and adjust it to your needs if you like it. Just don't change anything radically, cause in its deceiving simplicity there is a lot of reason. In fact 2-3 months of reasoning. There are no random distances there. Tony changed it a bit and you can see his great looking machine. He made it from 80x80, mine is 100x100x3
If you look at my thread i have a frame soldered in my garage with the same design and it has deflection under 100kg of load which is irrelevant.

Now what Dean says about resonance is true. Its not the same as stiffness. In fact in some cases the stiffness will help the resonance, especially in our case where we build machines from thin walled profiles.The great thing about my design is that all the forces are working only at the upper part of the structure, its stiffness does not depend at all of lower elements. The legs are just legs / i am talking about 100x100 or short 80x80/.

Now there are hundreds of points why resonance will not happen at all in the machine i am building, nor twist or bending, even if i were able to route deep aluminum and why not steel / which will not happen cause i limited it with 0.8kw spindle/ . This points are too long to explain, but be careful, cause these are particular decisions, like that the machine i am building will have 100mm thick MDF bead, underneath plastic sheet or aluminum sheet and etc...

Long story short, just take a look and study it. Use it if you like it. It implement Deans idea of the shorter table. Also implements subtle ways of dealing with resonance, like the beams of the bed gradually don't coincide with the short vertical ones. In fact in my next build everything will be slightly offset here and there, to kill the harmonics.
The best thing is if like Dean says the bed beams flex, at a later time can be added ribs bolted to them vertically and if there is a twist , you can add the same Z diagonals like in Deans drawing of the lower part just drilling from below and bolting. Add if when you need, why overbuild now? Not to speak of that with 100x100 profile is way overbuild as my measurements show on my build.