Welcome to the SeeMeCNC Community

Hello I wanted to know what the minimum layer thickness for the Rostock Max v2 is. Have been thinking about getting a delta and want to compare res of various models.
Rostock Max v2 = ?
Deltaprinter = 0.1mm
Spiderbot = 0.15
Kossel Clear = 0.1mm
BI V2.5 = 0.05mm
Atom = 0.05mm
Tripod maker = 0.07mm
ZeGo = 0.07mm

Outside of SLA printers( and even there) it's a pretty meaningless value.
Almost any FDM printer will let you print at 0.1mm or lower, but getting good results at that can be quite tricky.

If quality is your primary concern, you'd need a smaller nozzle than the standard 0.5mm provided.
But if you've never used an FDM printer before, I will warn you that getting quality prints out of any of them is a lot more involved than slice model and press button. And things get harder as layer heights drop to 0.1mm and less, and smaller nozzle sizes make things harder if you don't know what you are looking at.

Polygonhell wrote:Outside of SLA printers( and even there) it's a pretty meaningless value.
Almost any FDM printer will let you print at 0.1mm or lower, but getting good results at that can be quite tricky.

If quality is your primary concern, you'd need a smaller nozzle than the standard 0.5mm provided.
But if you've never used an FDM printer before, I will warn you that getting quality prints out of any of them is a lot more involved than slice model and press button. And things get harder as layer heights drop to 0.1mm and less, and smaller nozzle sizes make things harder if you don't know what you are looking at.

I mainly want to print objects and then use them to cast in metal like lost wax casting, I heard you can do that with objects printed in PLA. If the print quality is too rough it would just be a mess when cast in metal

I would find someone locally and see some samples of what's possible, you need to set your expectations. you can print some really very good quality parts, but it requires a lot of time invested in calibration and experimentation.

All the printers you list are mechanically similar, i.e. There is no real reason to the variation in listed minimum layer thicknesses for a part of a given radius. The manufacturers are merely picking a number out of thin air, it might be based on how low a layer height they have actually printed.

At very low layer heights, things get tricky, the plastic is stretched when it leaves the extruder and tends to break, and with a 0.5mm nozzle it will reach a point, where you can't even bridge infill. Smaller nozzles help because the plastic is stretched less. You can increase the extrusion thickness to compensate to some extent, but that isn't a panacea. You also start to see different artifacts on the walls caused by issues with the extruder having to run too slowly and the nozzle being so close to the previous layer, you can increase print speed to compensate, but that introduces issues of it's own.

You can get great looking models, don't get me wrong, but eking out that last bit of quality is as much an art as it is a science. Acceptable quality is something you'd have to decide for yourself.

Can you sandblast with the finest abrasive to remove the ridges (layers)?

Never tried it, I had considered tumbling the models, but my expectation is it won't.
Probably the easiest solution would be to use some sort of filler, either a paint designed for filling imperfections, or perhaps given you're application some sort of wax.

There are a few people who've done what you are trying to do, I'd do a search on the reprap.com forums and try IMing people to see what they've used.