Re: Wiper Arm Question

From: John Male (
Date: Thu Feb 20 1997 - 13:49:17 EET

We have been running an SLA 190, without a wiper arm for a couple of years now with the SL5170 resin. To work
out the wait times, you need to look at a value called the critical circle diameter, CCD. This is defined as
the diameter of the largest circle which fits entirely inside the solid portion of a slice cross section.
So for each layer, if you find the CCD, there is a table below which you can look at to get the wait time that
you need to leave for that layer. You need to do this going through the part, finding the different CCD's.
The layers can be grouped together, so if between a z height of 7.5mm and 10mm, the CCD's are the same or
similar, group them together so that you will get a wait time for that portion of the model. Do this for the
whole model, so that you get a series of wait times for different portions of the build.
You can then add in different recoat styles into the partman file for different z heights, and edit them to put
in the wait times.
Here is the conversion table to get the wait times. These values are given for a layer thickness of 0.15mm.
Going thinner than this, you will need to increase the wait times further, but we don't have any values, so you
may have to experiment a little. Use a wait time of 10 seconds for supports.
Range of CCD's (in mm) Z wait time (in seconds)
0-3 15
3-6 30
6-10 60
10-13 105
13-16 140
16-19 170
19-22 195
22-25 215
25-29 240
29-32 260
32-35 275
35-38 290
38-41 315
41-44 345
44-48 380
48-51 410
51-54 445
54-57 480
57-60 520
60-63 570
63-67 620
67-70 670
70-73 740
73-76 805
If you need to use a wait time longer than 999 seconds, you need to edit the filename.r build file.
I hope this is some help, and be warned that you may get bubbles trapped in the parts if you aren't using the
wiper arm.
Good luck


John Male
Research Student
Centre for Rapid Design and Manufacture
Buckinghamshire College of Higher Education
Queen Alexandra Road
High Wycombe
HP11 2JZ

Tel 01494 605085 Fax 01494 538593

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