Initial design advise wanted

[fifa]

It is your design, your money.

5m/min with 10mm pitch is 500rpm.

It is better to choose 2020 screw...

I do not understand why you need "rapid" speed. It is hobby machine, and it is CNC. You do not need to be with machine to do the work...

It is relative very easy to "limit" the spindle "wobbling" - 2 nylon bushes do the job (bushes must be splitted axially and loaded with spring to omit radial clearance...

Check the motor torque curve - steppers are not good at high speeds, therefore belt pulley reduction does not work....

For whatever reason link do not works. I am suggesting to do the "bed" form cheap "cast" (epoxy concrete - cheaper than welded structure), gantry must be designed to be torsional stiff, however it is better that laterally it is flexible - to reduce loads caused by rail misalignment...

regards

martin

[driftspin]

It is your design, your money.

5m/min with 10mm pitch is 500rpm.

It is better to choose 2020 screw...

I do not understand why you need "rapid" speed. It is hobby machine, and it is CNC. You do not need to be with machine to do the work...

It is relative very easy to "limit" the spindle "wobbling" - 2 nylon bushes do the job (bushes must be splitted axially and loaded with spring to omit radial clearance...

Check the motor torque curve - steppers are not good at high speeds, therefore belt pulley reduction does not work....

For whatever reason link do not works. I am suggesting to do the "bed" form cheap "cast" (epoxy concrete - cheaper than welded structure), gantry must be designed to be torsional stiff, however it is better that laterally it is flexible - to reduce loads caused by rail misalignment...

regards

martin

Dear martin.

It is as always a trade of isnt it?

stepper : ballscrew pully's 1:2 results in 400 steps per 10 mm right .. so... resolution would be 10/400=0.025 mm per full step right...

Microstepping does not count for repeatability or precision right?

I did actually think 1:2 reduced 1610 and 2010 was generally accepted as the better solution here for alu and hard wood machines diy builds on this forum.
Or am i wrong here?

When one would use 20mm pitch ballscrews... what would you suggest the reduction should be like and keep some resolution?

If i would not need speed i better go for 1605? low rpm and low speed high resolution.


Using 2010 ballscrew on a 1500mm span looked like the best trade of to me. speed vs critical speed vs inertia price.

And yes... it is gonna be expensive

For controls it looks like uccnc 300eth has the affordable price quality i like... not decided on this though...

The most amount of money is not in C7 ballscrews anyway.. it is in linearguides and and bearings ... shipping and tax...


Do you feel i should make a radical move / design change?


Scrap the frame buy an used tank chassis?


And if yes... can you suggest what you would change at this point in the build.



I am open to any suggestions...
The build of the machine is part of the hobby right :-)



Grtz Bert.





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