Quite an Unusual one

[JAZZCNC]

So you say there will be no sense to make the design as you suggest with one ball screw, 2 nuts and 2 and 2 fixed bearing supports at both ends? I mean only one fixed end will be enough? The bearings doesn't seem very big to me.

You miss under stand me I think.? . . . . . I would use 1 x screw with 2 fixed ends and tension the screw and if backlash was important then I'd use 2 ballnuts.
Correctly sized screw will have no issues with this setup if the forces are small like you predict.

[Boyan Silyavski]

You miss under stand me I think.? . . . . . I would use 1 x screw with 2 fixed ends and tension the screw and if backlash was important then I'd use 2 ballnuts.
Correctly sized screw will have no issues with this setup if the forces are small like you predict.

Dean thanks for your time!

I started already redesigning it to go with one screw and 1 or 2 nuts as you suggested. That will save me for a beer or two. I understood you correctly, but messed with my English.

What i meant is if there would be additional benefit if i fix that screw both ends with double fixed end supports, meaning 2 supports each side chained together and then tightened by the nut at the end.

[John McNamara]

I have seen Pre tensioned ball screws in large CNC machines, Also many where one end is fixed in preloaded angular contact bearings While the other is allowed to float in to allow for changes in temperature. The floating setup may be a less difficult setup to use, particularly if the frame is lightweight. If you pre tension you are imposing a substantial load on the frame, It would have to be stiff or it may be deflected out of alignment by the preloading stress, and the deflection would be likely to vary with temperature.

[mitchejc]

Silyafski, I really don't know the first thing about making those drum surfaces but the other day I saw this video and thought if this kind of forming process might not work for you as an alternative to hammer forming the sheet metal.
https://www.youtube.com/watch?v=eh0d...8P7aRhF_WqV0Ug

[Boyan Silyavski]

Silyafski, I really don't know the first thing about making those drum surfaces but the other day I saw this video and thought if this kind of forming process might not work for you as an alternative to hammer forming the sheet metal.
https://www.youtube.com/watch?v=eh0d...8P7aRhF_WqV0Ug

Exactly. Thats one of the reasons i made such strong Z and the cheese holes on the Z. I will not push the spindle bearings, instead will fit it somehow directly to the boxed Z.;

[Boyan Silyavski]

Some updates. 2 very hot weeks, especially if you are working alone in 70% humidity, 40C temperature and soldering all day long +weekends and moving heavy stuff.


Had to clean all stuff from the garage. Draw white lines for the footprint. This machine will take a lot of space. Of course it rained right after i took everything out, did i tell you it hadn't rained like 11 months.






Started with the gantry. decided to keep sides square, so later could flip and support easier the gantry. Do you see the blotch further on the floor. Guess what, just before starting all my boxes with paint fell on the floor and some spilled. A little diversion :-)





I have mixed feelings about the Evolution saw. While the motor and blade is great/made in japan/ the saw is very very flimsy. Next project will be to throw away the base and do a new one. I wish i have bought the Makita. It was 100eur more expensive and don't come with blade- another 100, so thats why. Anyway, an essential machine for the project.



Ventilator to cool myself and change of plans. The 60x60 profiles cut to size that were meant to support the rails were discarded. There was no way i can solder them from all sides. Instead i cut all of the 60x10 plate/6m in total/ and decided to separate them by the 60mm using at least the profiles i have already cut. Some carefull soldering from here and there. Very rigid result.




As you see from the pictures above everything is soldered till the end. Now there was another momentary decision. No legs for now untill i decide something clever and the steel from the legs went just inside the sides of the machine. So stair like sides with no holes, there lie the rests of the profiles meant for legs.




I cant explain how strong that machine frame feels. Including that bestial gantry. Vertical bend or twist- i did not even bother to measure it with the indicator. Its solid as a rock. starts to look like a Frankenstein thing from movie.

So today i finished working at 20.30 and couldn't help but move all elements with last available effort, as i wanted to see how it would look. I am a strong man, no lift or whatever help, so i am becoming stronger moving all day these pieces around while soldering. Did i tell you that all the soldered pieces weight around 500kg .


So here is my baby. Its huge. I am a bit surprised how big that is. Still has no name but i think it would be something military:




So after ~15kg of wire, 2 CO2 bottles and some crazy days i start to see how will look. Still have no color in mind.

[GEOFFREY]

looking like a really solid lump!!! How about drab (a sort of olive green) and "big bertha"? Well done. G.

[Clive S]

So here is my baby. Its huge. I am a bit surprised how big that is.

I have found you a ball screw to fit it:-

Attachment 13332

You might need bigger servo's though. ..Clive