Hi folks,
(BEGIN NITPICK MINI RANT)
I'm doing a clone of the S.S. Cassiopeia, based on the plans on the JimZ site.
The plans, available both as .TIFF and .PDF, include fin patterns. But the fin patterns don't include a ruler for scale. How much can I trust the sizing in the plans?
Normally, if a fin is off by 2%, it really doesn't matter much. But in the case of Cassiopeia, those fins will need to mate up with a ring fin, and I want to do all in my power to make sure they are as close as possible (within my ability to cut patterns out of balsa!) so that the fins and the ringfin mate up well.
YES, I know laser cut parts are available from SEMROC. But I'm doing this one by hand, so I want to get it right, and it's a general thing about plans without scales from any source, rather than a specific thing about this plan.
Using the PDF, if I just print it out, it would definitely come out about 4% too small due to "printable area" and scaling things that happen automatically on my combination of OS / Adobe Reader / Printer driver.
However, I've got AutoDesk Design Review softare that lets me dial in a percentage scale, and I know from experience that if I scan something in to a PDF, and print it out at 100% from AutoDesk, it matches the original item exactly to within my ability to measure.
So, generally, I trust PDFs, as long as I print them out at a defined 100%.
HOWEVER. In this case the fin pattern sheet also includes one of those wrap to mark the fin location guides. And if I print that sheet at 100%, and try to use the guide, this is what I get:
It's off by between 1-1.5 mm over a span that should be around 80 mm. So, depending on measurements and stuff, as much as perhaps close to 2%. Again, if this was a Red Max or some such, who cares? But with parts that have to mate, I get a bit jittery.
Maybe the guide itself was printed too small so the scanned guide is at actual scale based on an incorrect original (I see incorrect original wraps all the time, which is why I don't usually use them...). Or maybe the process to make the PDF was a bit off.
In the end, this isn't a HUGE deal... I can make the fin extension slightly oversized so that when I get the ring fin (Which I don't have yet) I can measure and make it perfect... but I thought I'd check for guidance on stuff like this from those with more experience than I have.
And yes, I know this is a nitpick to death issue. My likelihood of transfering measurements to balsa and cutting them out probably include more error than I'm dealing with here. So I'm grounded in reality. I'd just like to start off as good as possible...
For anyone who scans plans... please include a definitive size reference!
(END NITPICK MINI RANT)
(BEGIN NITPICK MINI RANT)
I'm doing a clone of the S.S. Cassiopeia, based on the plans on the JimZ site.
The plans, available both as .TIFF and .PDF, include fin patterns. But the fin patterns don't include a ruler for scale. How much can I trust the sizing in the plans?
Normally, if a fin is off by 2%, it really doesn't matter much. But in the case of Cassiopeia, those fins will need to mate up with a ring fin, and I want to do all in my power to make sure they are as close as possible (within my ability to cut patterns out of balsa!) so that the fins and the ringfin mate up well.
YES, I know laser cut parts are available from SEMROC. But I'm doing this one by hand, so I want to get it right, and it's a general thing about plans without scales from any source, rather than a specific thing about this plan.
Using the PDF, if I just print it out, it would definitely come out about 4% too small due to "printable area" and scaling things that happen automatically on my combination of OS / Adobe Reader / Printer driver.
However, I've got AutoDesk Design Review softare that lets me dial in a percentage scale, and I know from experience that if I scan something in to a PDF, and print it out at 100% from AutoDesk, it matches the original item exactly to within my ability to measure.
So, generally, I trust PDFs, as long as I print them out at a defined 100%.
HOWEVER. In this case the fin pattern sheet also includes one of those wrap to mark the fin location guides. And if I print that sheet at 100%, and try to use the guide, this is what I get:
It's off by between 1-1.5 mm over a span that should be around 80 mm. So, depending on measurements and stuff, as much as perhaps close to 2%. Again, if this was a Red Max or some such, who cares? But with parts that have to mate, I get a bit jittery.
Maybe the guide itself was printed too small so the scanned guide is at actual scale based on an incorrect original (I see incorrect original wraps all the time, which is why I don't usually use them...). Or maybe the process to make the PDF was a bit off.
In the end, this isn't a HUGE deal... I can make the fin extension slightly oversized so that when I get the ring fin (Which I don't have yet) I can measure and make it perfect... but I thought I'd check for guidance on stuff like this from those with more experience than I have.
And yes, I know this is a nitpick to death issue. My likelihood of transfering measurements to balsa and cutting them out probably include more error than I'm dealing with here. So I'm grounded in reality. I'd just like to start off as good as possible...
For anyone who scans plans... please include a definitive size reference!
(END NITPICK MINI RANT)
