Does anyone have suggestions or test files that they would recommend for testing accuracy and precision? I don’t have any specific concerns or issues with my Maslow. I’m just curious about testing it and having a point of reference on expectations as I get into larger projects.
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I would also like to know what people have used. I guess I could see doing lots of parallel lines or nested L shapes along the edges and then some circles spread out and then some different depth square pockets here and there. You could measure distances between the edges of the L shapes, you could measure length and width of the circles, squareness of a rectangular array and then depths and square sizes.
This guy is doing inside and outside squares. Cut Test Samples Created by Philip1 — Files created to test cuts in different materials and with different bits.
For the Maslow speicifically I would want to do some large scale patterns because we have changing forces and theoretical accuracy near the edges and corners
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This is interesting. Actually this could be a good test, one at every corner and one at center home. You would have to run it on multiple sheets, though, so a lot of waste. A pen adapter would probably be good for a first test, but running it under load would be necessary for any final results.
wouldchuck wrote:
I would also like to know what people have used. I guess I could see doing
lots of parallel lines or nested L shapes along the edges and then some
circles spread out and then some different depth square pockets here and
there. You could measure distances between the edges of the L shapes, you
could measure length and width of the circles, squareness of a rectangular
array and then depths and square sizes.This guy is doing inside and outside squares.
Cut Test Samples Created by Philip1 — Files created to test cuts in different materials and with different bits.For the Maslow speicifically I would want to do some large scale patterns
because we have changing forces and theoretical accuracy near the edges and
corners
I have a couple grids at Index of /maslow a 1’ square grid with lines
every few inches, and one to cover the full 4x8 sheet
they don’t set the Z distance, just move the sled in the grid.
The idea was that you can use a pen or v-bit, set the Z height to just touch the
material and then execute the file and manually retract at the end of the cut.
David Lang
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I had a guess you had something hiding somewhere. Haha. This is perfect. Im doing some repairs on my machine but this is the first thing I’ll do once I’m done.
JimB wrote:
I had a guess you had something hiding somewhere. Haha. This is perfect. Im
doing some repairs on my machine but this is the first thing I’ll do once I’m
done.
I’d run them first with no bit and the router not running, and only then do
something that you can then measure
David Lang
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I have created an error compensation program to overcome accuracy issues, which seems so far to be doing what I intended.
My motivation is to not make scrap out of 4 x 8 sheets of marine plywood, which I intend to start cutting within the next couple of weeks.
I have used the X and Y scaling factors included in the current software, but found that the errors are not so simply corrected.
This is my first Github repo - please let me know what I’m missing 
JoeS
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Joseph Schroeder wrote:
I have created an error compensation program to overcome accuracy issues, which seems so far to be doing what I intended.
This is a good approach to try
when you are doing your grid, try various grid densities, some past reports have
shown that the error changes significantly in a short distance from the edge.
I look forward to seeing more (and seeing what error grid you report
how are you measuring the distances? just a tape measure?
I have used the X and Y scaling factors included in the current software, but found that the errors are not so simply corrected.
to be expected, they are just a crude hack and we know the errors are not linear
This is my first Github repo - please let me know what I’m missing
looks reasonable.
David Lang
I think my next steps will be to compensate my 80" x 40" grid (using the error map I’ve got, which was included in my initial commit), draw it again, and check it. Then I could test the extremities by extending the grid to the edges, but I’ll need to cobble in some support outside of my spoilboard.
This will tell us if the Scipy (linear) extrapolation is good enough, or if the grid does need to be denser or bigger. Linear isn’t the only option, either.
I drew my full size boat bottom using the current maps, and it came out very close to design, but yes, I’m using a tape. Sigh. From a guy who spent the last 20 years doing high end metrology with structured light and photogrammetry.
I’ll probably not get much done for the next couple weeks… got tickets to the Masters!
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Joseph Schroeder wrote:
I think my next steps will be to compensate my 80" x 40" grid (using the error
map I’ve got, which was included in my initial commit), draw it again, and
check it. Then I could test the extremities by extending the grid to the
edges, but I’ll need to cobble in some support outside of my spoilboard.This will tell us if the Scipy (linear) extrapolation is good enough, or if
the grid does need to be denser or bigger. Linear isn¢t the only option,
either.
with a tight enough grid, linear will work. the only question is how tight a
grid to you need
I drew my full size boat bottom using the current maps, and it came out very
close to design, but yes, I’m using a tape. Sigh. From a guy who spent the
last 20 years doing high end metrology with structured light and
photogrammetry.
I put together a vernier attachment you can add to a tape measure, take a look
at this onshape project
accuracy will depend on the precision of your 3d printer, but should be pretty
easy to print and get something significantly better than just a tape measure.
If you get it printed on a resin printer, make sure the slots get cleared out
before you fix it under the UV
(also, look at the ratings of the tape measure, there used to be class 1, 2, and
3 tape measures, but there was a change a couple years ago)
David Lang
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