Thanks, that helps. I’m adding calculating the radius and centers of those
circles to the sheet.
it seems just too easy that they are circles 
arjenschoneveld wrote:
the path of the cornerpoint of two lines with a fixed angle we talked about? it is a circle/arc
David Lang
I created a new tab on the sheet “M4 cut area from frame size” and I have it down to:
enter frame size
create a graph matching the frame size
plot 4 green circles of this radius at these positions
plot 2 red circles of this radius at these positions
plot 2 red circles of this other radius at these positions
what’s green is where you can cut
ideally there would be an additional check for min and max belt size, I don’t do anything with that yet
the formulas are a bit hairy to go through, they are up in the orange section to the top right. They allow for different min angles for top/bottom vs sides.
I have not been able to figure out how to get google sheets to draw yet, but you can copy the formulas to other languages to plot them out (I’ll be happy to help, but it’s now past 2am for me so I’m calling it a night)
I now have it writing almost correct svg graphics (it appears correct when you view it, but when you copy/paste it has all the double quotes doubled and an extra double quote at the beginning and ending)
it places a rectangle the size of the work area selected in the checking section above it
sample image at http://lang.hm/maslow/maslow_frame.svg (4265x3525)
Hi David
this is fantastic work!
Iḿ not at my home computer right now, so I cant check graphically, will do that tomorrow night. My browser does not support svg apparently, but I saw your sample. together with the rectangular workarea, I think it is very clear.
I think you are already trying to let google sheets draw the image , and when that works your spreadsheet is valuable. Might be a good idea to make a new one, solely dedicated to the maslow4? I think that would be less confusing and thus more usable for more people. ( Iḿ not really into spreadsheets, so I know it is confusing 
)
Well Done!
Arjen
I’ll wait for the final numbers from you clever guys, but I may end up making the anchor points removable, so spoil board and runoff areas are the only “fixed” parts.
Hi David,
I checked a bunch of different framesizes in your spreadsheet, couldn’t find a fault 
would this already be posible: enter frameheight, enter framewidth, enter desired width of the workarea, and then the spreadsheet suggests the max height of the workarea? That way people can tinker and directly see the result of their changes.
Arjen
I had the same thought, I’ve got it where you enter frame width, frame height, workpiece width and it returns the available workpiece height. I can have it do the other way as well
I added a pair of fields so you can also enter height and it will calculate width
a neat thing about this is that you can change the angles from the pulldown and it will recalculate the available cutting area and change the sizes (the graph and angle checker section are based on you entering the width and it calculating the height)
I also now have it check the top/side angles and limit the calculated width/height if those angles get out of spec (i.e. you get too close to the side for the belt between the adjacent anchors to work properly)
Does the graph auto update or do i need to allow something for it to generate as all I’m seeing is a window of text
Martin wrote:
Does the graph auto update or do i need to allow something for it to generate as all I’m seeing is a window of text
it creates the text that if viewed as a web page (and fixing the double quotes,
replace “” with " and remove the " at the beginning and end)
would be a graph. I don’t know how to do the graph within the sheet that shows
this properly
David Lang
If you save that text as a file something.html and then view it with your
browser (file://something.html or something like that) it should display the
graph
file:// doesn’t work as I hoped 
save the data in that to a file called maslow.html
then (on linux and probably on mac) run this command to fix the quotes (that is single quotes around double quotes, hard to see in the forum here)
sed -e s/‘^"’// -e s/‘"$’// -e s/‘“”’/‘"’/g maslow.html >maslow2.html
then open it with a URL similar to
file:///home/dlang/maslow2.html
(the exact path will depend on your username and with mac I think it’s a bit different) and you will end up with something similar to http://lang.hm/maslow/maslow_frame.html as the result
very neat!
FYI, I’m working to convert this to javascript (fully self contained in the browser)
It’s been a few years since I’ve done much javascript work, so I’m having to re-learn things. :-/
I’ve got a basic form together that lets me enter data and change things. now I’m starting to go through and add the calculations rather than spitting out a pre-canned graph. This is intended to be a browser-side thing, so very lightweight, and I’m hoping that eventually this can be added in to the firmware so that when you are entering the frame size pre-calibration, it can generate this graph and show you what your effective cutting area is (and either automatically set the calibration to stay within this area, or warn you when it will stray out of the area)
Thank you all for your work on this. I’m definitely interested in this thread as I am beginning to think about drilling holes for anchor points in my garage floor. Definitely want to get that right the first time. I’ve read through this thread and will probably need to read through it and play with the spreadsheet to truly understand it, but are there any general takeaways to share?
For example, the previous advice has been that spreading the anchor points out farther (that is, longer belt extension) is generally good. Is that true here as well?
Are certain aspect ratios [examples: 1) square or 2) matching the desired work area] beneficial, or will we have to run a new analysis for every work area?
Do the results scale? Could you run the analysis for a 4-foot by 8-foot sheet of plywood and be able to say something about a 1m x 2m work area?
This is a game of angles, but the area you can cut is not intuitive and not a nice relationship to the aspect ratio. poke around at this link and you can get a feel for how it works fairly quickly.
I now have the maslow4.html file working.
It lets you set your frame, pick what set of angles you want to use:
From Bar: the 40 degree angle that Bar said is the closest arms can get to each other
From CAD: the slightly narrower spacing that the CAD model of the arms indicates may be usable
Clipped ears: if you remove the upper ears and guards around the lead screws, add a slight spacer, and shorten the screws that hold the lead screw nuts, you can get better angles
Custom: for you to enter your own numbers (not yet implemented)
It will then show you the green area you can cut, and the red areas that are too near the sides. It initially shows you a 4x8 workpiece, but if you set either the X or the Y value, it will set the other to the max that will fit in the green area.
you can uncheck a box to allow it to go into the red areas (but it stays in the green area), I may change it so that when you uncheck the checkbox, it doesn’t update the other dimension instead (thoughts)
@bar, this is very small, (<9k) feel free to integrate it into the firmware. I could see the calculations of safe areas being useful, and possibly even the graphics so that people can see what areas they can cut.
the logic in the update_x() functions could be used during calibration to skip any test points that the machine cannot reach for example
