Tolerance For printing Directly onto bed

Good Day fellow printerers.

I am Experimenting with printing directly onto the form 2 bed with no supports for our medical device handle to eliminate post processing since we are producing up to 2 large handles >8 pieces per day.

Getting the Dimensions right has yielded the following information.

0.1mm Layers
Grey V3 Resin

A cylinder with a height of 90mm was printed Producing a printed height of 89.15mm 0.94% shrinkage in Z direction
XY Dimensions where spot on 31.1mm in the model became 31.1mm Printed.

Does Anyone know of any clever tricks for printing straight onto the bed? I am struggling with part removal. Currently I heat the platform slightly with heatgun on minimum temperature.

Well, mostly I use the white and clear, i print on the bed all the time, no problems…I do clean it with alcohol after removing each print, i have a spray bottle, and just wipe with papertowls. I use artists pallet knives to pop it off, way much easier for me than what was provided, thinner, smaller…Don’t know if that helps.

The short Z height is due to the layer compression at the start of the print. These layers are compressed a bit and cured a bit differently.

You will likely find that the Z offset is a hard number and not a percentage. Keep in mind that the machines are rarely exactly square and that resin trays effect this delta also. It will even move around a little in different areas of the tray.

Right you are.
I just printed another model that had removal features in the first 0.8mm of the print (attached to the bed). The features where not there in the final print. So it basically prints the first 0.8mm of the model in 0.1mm above the bed.

There was also some horizontal artifacting throughout the print mainly in the first 20mm though.

Try adding a 1-2mm raft, or base, or anything (not in PreForm, but in MeshMixer or 3D Builder) that will attach to the build plate and absorb the first couple millimeters of compression forces. After that, the actual object should be the correct dimension in the z axis since it was not compressed at all. Just have to buzz off the sprue/base/raft thingy. It really depends on what you are printing though, this may not be possible for you, just thought I would throw it out there!

What is this magical technique you call buzzing? :smiley:
The objective here is primarily to remove post processing requirements since we are getting up to maximum throughput of the printer to keep up with production requirements and clipping/sanding the parts is killing us on time.

But Yea, maybe something with lower density on the first layers which will compress without leaving excess material that affects higher layers.

lol… It’s a very technical term :slight_smile: I guess my thought was, better to remove one support than 30. I got the idea from the dentist that is on all of FL’s promotional stuff. Video linked here: