AccuBend Freedom and Channel Letters - Tips?

[AdmiralSigns]

Place I've been working at got a CNC router about 1.5 years ago and while we've been doing great without signs, we've hit a snag with channel letters. Letter back and faces are accurate(with the faces being outline offset), but now our returns don't seem to be matching up. At first we thought it was an issue of the faces not matching the backer and returns. I called a Computerized Cutter technician and gave me the usual steps(Notcher file first, cleanup, .-02 inline for letter backs, compensate for Bit width, etc.) and the backs fit inside the returns, but recently we've been having issues having faces fit on the returns. A .12" offset used to work, but sometimes we needed to go all the way to .25, which would still leave one side too open. I noticed that even when we make returns of letters that are literally just Lines with no arcs(letter T for example), the returns still come off a bit warped. We don't weld the returns, but use a Clinching machine. I just don't want them to have to waste time having the cut the faces manually(since that's why they got the router for).

For anyone who uses an AccuBend Freedom, are there any self imposed guidelines you use when making the notcher files? I've read making sure stroke width is more than 1", sometimes even not even below 2", and if we HAVE to make serif letters, to make sure the serifs are also at least 1". We clean the Freedom regularly as well.

 

[MikePro]

hate hate hate serif lettering on the accubend, but we've managed to make it work via a bunch of calibration testing & value inputting.
its been so long since we've had to go through the process, but our CC tech walked us through it at the time.

beyond that, your offsets are the same as mine. approx. .125" offset from aluminum shape is the plexi shape, and .02 offset from aluminum shape to make the accubend shape (assuming you're using .04" coil)
node editing is crucial as well, as the machine does not like having a curve before a bend, so I manually add nodes and convert arcs/curves to lines at hard bend points.

 

[AdmiralSigns]

hate hate hate serif lettering on the accubend, but we've managed to make it work via a bunch of calibration testing & value inputting.
its been so long since we've had to go through the process, but our CC tech walked us through it at the time.

beyond that, your offsets are the same as mine. approx. .125" offset from aluminum shape is the plexi shape, and .02 offset from aluminum shape to make the accubend shape (assuming you're using .04" coil)
node editing is crucial as well, as the machine does not like having a curve before a bend, so I manually add nodes and convert arcs/curves to lines at hard bend points.

That part I was not told about. So basically if there's a curve going into a line, I should convert the end of curve to a line?

 

[MikePro]

That part I was not told about. So basically if there's a curve going into a line, I should convert the end of curve to a line?

its at the bend.
if there's a curve that goes into a hard bend, i'll add a node at .25"-.75" from the bend node and covert that small section to a line.
(now I'm noticing that i missed one at the top!)
there may even simply be a value that is mis-calibrated that would allow me to skip this process, but its what works for me everytime now.

pics for reference, as this shape has multiple instances of curve-to-bend.
with added node clusters and curve to line conversions.

as far as calibration goes, i'm at a loss on how it was accomplished at the machine or at least well enough to explain how to find the right values & input into the accubend dialog menu, but my Arc Variables & Adjustments page is attached as well.
I wouldn't assume that my values would work for your machine, as I have a different model with different parts & assembled in another decade. lol
but I DO remember that it was noticeably inaccurate "right out of the box" and my computerized cutters tech was able to walk me through the whole process at the time.