El Beast - Initial design phase, comments and critique welcomed!

[Boyan Silyavski]

Why do you think it would it be more rigid?





Personally I think the machine as a whole will be more rigid with the current setup as it allows me to bolt the frame and frame supports to the tool bed for added frame rigidity while keeping the unsupported gantry arm to the minimum length. If I flip the supports 90 degrees and set them up like my current machine then I have an unsupported bed that will flex, and I can't put the cross supports in as they would then interfere with the ball screws... unless I underslung them which would be a mounting nightmare.

Yes, it would be. But there is the challenge to align all.

The only way to align that easy and properly 100% is to rest all frame on flat surface and lift rails on paralel blocks same size and then tighten. But i assume you dont have that flat surface. So you may have to think of sth else. What i am saying here is that a design is as good as you know all steps, to finishthe machine. To figure the details meanwhile you are building it=wasted money and time

[Zeeflyboy]

Thought we already mentioned that the rails would be aligned to the ecocast ground bed plate?

I'll be using Thorlabs precision corner brackets for frame squareness (combined with the ecocast end plates and milled extrusion).

Does that not cover the alignment issues, especially given the relatively small size of the machine?

[Boyan Silyavski]

They will be aligned left-right, not up-down , plus have to be straight up down, not wavy, same for left right, but as you said that will not be a problem as eco cast plate. 3d, means there are 3 directions that things have to be on plane

[Zeeflyboy]

No, they would be aligned in the vertical plane too... ecocast bed plate could be fastened to the top and then I would insert a shim of 2.5mm between carriage and bed with the carriage at one end, clamp it in place and tighten end screw. Move carriage to other end, insert same shim again and clamp. Tighten that end screw... If required you could repeat that at several points along the length.

Repeat on the other side and both rails are aligned vertically using the eco cast bed plate as a reference.

The parallelism and squareness of the Y-rails would be taken care of to acceptable tolerances by the captive ecocast end plates, milled extrusions and thorlabs corner brackets, while the vertical alignment (both in X axis rotation and Z plane height) would be done in reference to an ecocast bed plate.

What am I missing? In my head that ends up with the rails fully aligned in all axis to within the tolerance of the milled surfaces which should be sufficient for a pretty accurate machine all said and done.

[Boyan Silyavski]

Seems 100% ok what you are saying. Thats very similar to the way i thought it could be done.

[Zeeflyboy]

Ok great, thanks - glad you agree with my thinking then!

I've just done a mass analysis on the finished machine and its coming in at just shy of 190kg... I know mass is but one suggestion of rigidity but that's not far off 3 times the mass of my current machine.

I've also taken the opportunity to change to a HGR25 rail and HGR25HA carriages on the Y-axis since there is more space now.

Had a quote back for all motion parts, it was pretty reasonable for ground screws and HIWIN rails. Think I'm good to pull the trigger on those parts?

[fifa]

Few comments:
- I do not understand why you are using AL profiles and AL plates, check stiffness...
- design of lower (x) rails is .... You need to grind both surfaces to get perfect parallelism, otherwise will linear bearings feel the load caused by angular displacement of both rails , put them on the top of the table, in same plane - much easier for DIY,
- design of gantry (y) - it must be closed beam - it has no sense to do a "nice look" without functionality,
- side brackets, what is the method for setting the "true" right angles? Do you expect that everything will be machined within few microns? , y length tolerance stack is problematic anyway
- foots: do you expect that desktop is planar?, machine must be stable, it looks nice, but

Before design set the requirements i.e.
- max work space
- max space for machine
- max tooling dia
- material of machining
- define what you wish to do ( mirror surfaces, engraving...)

and the start with design.

regards

[A_Camera]

Ok great, thanks - glad you agree with my thinking then!

I've just done a mass analysis on the finished machine and its coming in at just shy of 190kg... I know mass is but one suggestion of rigidity but that's not far off 3 times the mass of my current machine.

I've also taken the opportunity to change to a HGR25 rail and HGR25HA carriages on the Y-axis since there is more space now.

Had a quote back for all motion parts, it was pretty reasonable for ground screws and HIWIN rails. Think I'm good to pull the trigger on those parts?

This is certainly going to be one of the most beautiful and best machines I have seen. Seeing and following your posts I am sure that the quality will match the beauty and it will not just be a "beautiful blond" with only good looks and sexy appearance, but it will also have massive quality and accuracy attributes.

I also like the idea of protective side covers, I think this is important because of several reasons, apart from the most obvious that it keeps most of the chips inside the working table area, it also works pretty efficiently when the cutter is broken and comes flying at you like a deadly projectile at high speed. I also have side walls around mine and that have stopped two such projectiles already from hitting me, so it is definitely a good idea to design that protection from the start. I actually don't understand how other people dare to run these machines without any protection at all, some not even using protective goggles. Perhaps they never make mistakes and never break a mill bit, I don't know, but that's their business.

The only thing I'd do differently in your design regarding the walls is that I'd make them easily removable, preferably without the need of unscrewing. This is because it helps placing the work piece/vice/measuring instruments and so on on the table more easily. It also allows working on longer than the table work pieces if you would need it some day.

The other thing you should consider is the mass. 190kg is a very heavy thing, which is very good for a machine, but it sets some requirements for the table also. No point building such heavy machine if the table it is on is not stable enough, which I am sure you know very well also.

The other thing about the mass you have to consider is the ability to move it around. Perhaps it is a non-issue, but anyway, if you one day have to move it just a little bit, it is going to be a very difficult task if you haven't thought about that during the design. My machine is only about 90kg but to move that around on my own is not possible, so I have to lower the machine on wheels to do that, and even so it is not something which is done in a minute or two, first I have to lift the machine then remove the wooden blocks it is standing on then lower down on two wheels and do the same for the back, or the front part, depending on where I start. Mine is standing on it's own feet, so it is a bit easier than it would be for yours.

Perhaps you have these questions covered/solved already, but before starting the machine build, I'd build the table to build it on and made sure the table is extremely easy to rotate and move around during the work. It is going to be necessary to have easy access to all sides, that's for sure.

Anyway, it is very interesting to follow up on your work and see the progress. Good luck with the rest of the work as well, and don't forget too keep us updated, both here and on the Zone.