Hey!

Great question – a 0.65 mm hole is typically obtainable in steel DMLS. The real questions are about hole shape, tolerance, depth, or curvature:

• Shape – round at that size will resolve OK, but if you have intentions of other geometries with sharp corners, like a spline or square, you should expect some feature overgrowth or distortion. This can be a challenge if you have a mating piece. At this channel size I’m guessing it’s more about being a vent or fluid channel so this may be a non-issue.
• Tolerance – as-printed holes are typically undersized from the CAD design. Small holes get an “echo” of thermal bleed causing oversintering since the opposite of the hole is being sintered so closely. I would project some level of deviation and if needed, offset your hole face by ~0.07-0.12 to compensate for undersizing. Again, if this is just an air channel or cosmetic then it may be a non-issue. Orientation of the hole in the build will also affect ovularity where it’s best fully vertical and worst at most horizontal.
• Depth – can we clear it with a pin or drill bit all the way? Thru holes are easier to clear out but if it’s blind think about that feature being full of metal powder that needs to be removed. The deeper the hole the more challenging it is to guarantee removal, especially if it isn’t circular.
• Curvature – I can use a pin or drill on straight holes to clear out unsintered material, not so much with curved holes. Similar to depth, if the channel is not line-of-sight then it is very difficult to guarantee and qualify that the channel is or can be cleared. Larger holes are recommended for non-line-of-sight channels.

I say all this because a lot of design for 3D printing is not just what the machine and material can do, but also how your CAD is designed. If you have the file uploaded on Xometry you can reach out to the support team to get feedback in context to your project. You’re definitely in the driver’s seat in DfAM!