Back to Ganoksin | FAQ | Contact

Removing build marks from resin models


#1

Need some suggestion.

How does one smoothen the surface of the resin models from the R.P.T
printer/ laser machine. Have tried using emery paer but it is too
time consuming,any other process?

K.H.Kotwal


#2

This is still the major problem with any RP model, how bad the
problem is depends on the machine and its settings of course but all
of them leave a surface that is not suitable for fine jewelry of any
definition. My solution has been to build to.2mm larger than the
desired size after shrinkage has been taken into account. This leaves
a cast piece with enough volume to allow for finishing to correct
final size with the traditional tools, files, abrasives and gravers.
I would be delighted to hear of a better way.

CNC milled waxes are often quite a bit better but again it depends
on the machine and the settings that the operator uses and there are
limitations of the mill itself as undercuts and certain other
geometries are not millable or are just too difficult to set up.

James Binnion
James Binnion Metal Arts


#3

Thank you James,

We get the RP models in 25 microns in the Laser machine. Still find
the Envision output sometimes better then the laser. Our designs are
quite delicate and we cut a RTV mold and then the wax pull out and
cast directly to Gold.

Regards
Khushroo


#4

My clients enjoy the smooth surfacing of the envisiontec perfactory
rp builder and it has castable material. go here for further
details…

I don’t see the surfacing being an issue with this type of rp
building as stated here. I would agree the added extra.2mm would
compensate for shrinkage and finishing processes, but not surfacing
on these models.


#5

Hi James,

The guys I’m dealing with use a proprietary wax formula, and they
get to 16 microns with that… which isn’t bad… they also mentioned
that they’re working on a way to make the model finer. I’ll tell you
more when I know more.

I’m going to take a couple of “excuse” computer renders in for
production, to check out where they’re up to with growing wax
models.

I’ll let you know.
Regards Charles A.


#6
I don't see the surfacing being an issue with this type of rp
building as stated here. I would agree the added extra.2mm would
compensate for shrinkage and finishing processes, but not
surfacing on these models. 

Then you are not as picky as I am. The Envisiontech Perfactory
output is one of the best I have seen but it still requires more
clean up than a good hand carved wax. Of course it makes very
accurate models which is why I use it but the surfaces still show
build lines and those have to be removed by hand finishing. This adds
additional labor to the finishing of a casting.

James Binnion
James Binnion Metal Arts


#7
The guys I'm dealing with use a proprietary wax formula, and they
get to 16 microns with that... which isn't bad... they also
mentioned that they're working on a way to make the model finer.
I'll tell you more when I know more. 

The micron thickness specified by the machine makers would at first
glance seem to be more than adequate. The issue is that they are
generating a voxelated (pixel picture element voxelvolume element)
model of a curve function. It is always going to be an approximation
of the original curve that will result in aliasing and other
artifacts. The artifacts of this process will always be there. Yes
you can make the voxel smaller but there are issues. One drawback of
going for higher resolution is that the build time goes up
geometrically with the increase in resolution. So if you half the
voxel size your build time goes up by a factor of 8 so an eight hour
build now takes 64 hours unless you can also increase the build
speed. Increasing build speed is not so easy to do.

James Binnion
James Binnion Metal Arts


#8

Hello James,

We use various tools for removing the build marks from the resin
models. Files in various sizes, shapes, cuts, fine grit papers, buffs
fitted on mandrels of micromotors some designed for finishing the
model. We use Invision Hr of 3 D systems, envisiontec, & solidscape
models. I will post the details if you need them. The logic we follow
is the same as we would finish a fine wax model.

Warm regards
umesh


#9

Hi James,

The micron thickness specified by the machine makers would at
first glance seem to be more than adequate. The issue is that they
are generating a voxelated (pixel picture element voxelvolume
element) model of a curve function. It is always going to be an
approximation of the original curve that will result in aliasing
and other artifacts. The artifacts of this process will always be
there. Yes you can make the voxel smaller but there are issues. One
drawback of going for higher resolution is that the build time goes
up geometrically with the increase in resolution. So if you half
the voxel size your build time goes up by a factor of 8 so an eight
hour build now takes 64 hours unless you can also increase the
build speed. Increasing build speed is not so easy to do. 

These guys run the printing fairly slowly. They have a lot of
machines, they have them running all the time.

The models are smooth to the touch, straight from the machine.

When I go, I’ll ask for wax samples, if I get some I could send you
one.

I was impressed the first time I saw one, and I’m quite fussy too
:wink:

Regards Charles A.


#10

Hi Umesh,

On larger models I have done what you mention. I do find the castable
resins to be more delicate than carving wax, so greater care is
needed to try to clean them up and it is harder to repair them when
you break them. Since most of the work I have grown is stone settings
they tend to be just too delicate to clean without damage so I have
them cast and then finish in metal. This is more time consuming but
much less likely to be damaged while cleaning them up

James Binnion
James Binnion Metal Arts


#11

Hi Umesh,

I’m looking for someone to print in the Invision HR material for me.
If you print for other people please send me your

Thanks,
Catherine