[mikewarot]

>could you use strain gauges to measure the deflection and fix it in software?

No. There's no substitute for rigidity in fixturing and of the machine itself. There will also be vibration motions that have unpredictable nodes, frequencies, and amplitudes.

Consider that a 2 flute mill at 20,000 rpm will induce vibrations with a fundamental frequency of about 670 hz. This would require a servo system with a bandwidth of about 2 khz to correct, a sampling rate of 8khz would be a bare minimum.

Next, what to do if the tool digs in, and shoves the part? You have to have backlash sufficiently damped, and rigidity enough to keep the tool or part from being snapped off.

There's a good reason machine tools are as heavy and rigid as they are, and why they must be on a thick foundation, and leveled precisely before use.

If you're going high precision, you'll also have everything in a temperature controlled environment, and allow the materials to soak at a day to achieve the proper temperature. Cooling is very important when you get into fractions of a millimeter, or "tenths" (1/10,000 inch) tolerances.

The best machine tools are old American cast iron machines from about 1940 to 1960, rebuilt with modern control systems.

[jerome-jh]

The rotary axis is controlled by a stepper motor. This is not a usual turning lathe. The rotary axis can be made as slow as necessary and the only relevant analysis is a quasi-static one. Answering to parent comments: there are usually no encoders on these machines. The controller firmware just counts the motor steps. If a motor misses a step, everything will be off from then. For the cantilever design: it is already used by Prusa 3D printers which are well regarded (in the field of amateur 3D printing) so I do not think this is an issue for the targeted accuracy which is typically 10 to 50 micrometers.

The only issue I have with this design is that the accuracy decreases with the distance from the rotary axis, hence it is not uniform over the building volume.

[Accujack]

>For the cantilever design: it is already used by Prusa 3D printers which are well regarded (in the field of amateur 3D printing) so I do not think this is an issue for the targeted accuracy which is typically 10 to 50 micrometers.

3d printers don't have forces pushing back on the print head, nor the vibration from a cutting tool to deal with.

This design might work ok for 3d printing, or laser cutting, or anything else where no contact between the working head and the material occurs.

As far as accuracy and repeatability, it's going to be about as good as the average 3d printer design. It's a nifty idea for a system, but it's only a decent machine for cutting if it's scaled up massively and built of cast iron or similar materials.

[kadirilkimen]

Depends on what you cut. It cuts wood pretty nice. I couldn't documented the wood cutting performance on prototyping. I will demonstrate it's wood cutting capacity in v1 release. It's a 3d printable desktop machine and never intended to cut precise metal parts. May be I can design a full metal body version with professional components like rail guides instead of plastic v-slot wheels.

[kadirilkimen]

It is 0.025mm on the outer edge of the table.