Re: SLA accuracy

From: Andrzejewski, Jan (
Date: Fri Apr 07 2000 - 18:25:23 EEST

Paul Border from Laser Reproductions asked what the acceptable tolerance for
SLA parts in the 18-20" (457mm - 508mm) long range is.

Not many will answer this one as it may impact on their ability to sell
their services.

Other considerations are that even though the operator may choose the best
parameters for accuracy, then builds test pieces to enable them to fine tune
the xyz scaling factors the problem then is that without user control of the
laser beam profile to maintain a constant and quality diameter output that
is within acceptable limits of deviation, you just might as well bang your
head against a brick wall then try to solve the problem.
This has been noted with 3D Systems as an upgrade requirement.

With only an SLA350 I can not comment on the sizes that Paul asks for but if
it is of any help here is what I tell my clients can expect with out the
laser throwing a wobbly.

XY accuracy up to 350mm lengths +0.10mm/- 0.05mm (+0.004"/- 0.002")
Z accuracy +2 x layer thickness
Vertical surface roughness (no manual finishing) > 5 microns

Layer thickness of 0.05mm and 0.025mm have been built for clients that have
improved on the above values but until I have full control it is not right
to inform clients of any changes.

Test boxes built for 3D Systems were recorded as max 3.1 microns and Min
2.0 microns for Vertical surface roughness.

XY accuracy for 195mm length sample is +0.02mm / -0.04mm

Jan Andrzejewski
RP Project Manager
Technology Centre
Nottingham Road
Melton Mowbray
LE13 0PB
Tel +44 (0) 1664 501501 Fax +44 (0) 1664 501556

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