# Printer geometry limitations?

I am certainly hoping this to not be the case, as everything I thought would work just fine (hell inventor could calculate the correct carriage positions!)

So what I've got is a bit of a long carriage to reduce the length of the delta arms. This of course means there has to be acute angles under the carriage to reach the full radius. Delta radius seems to subtract the carriage length and effector offsets from the printer radius, making me believe my design won't work with repetiier (and likely not any firmware out there). Is this the case? Do I have to get into the code to make my printer work! I knew I was in for a world of pain when I looked at the highway leading to 3d printer city and decided to veer off into the dirt to get there instead, but I didn't expect this level of work. Is there something I'm missing?

• The theoretical maximum radius is the rod length. Theoretical because at that radius one is horizontal and needs to travel much faster then the rest. What matters for calibration is the horizontal distance between rotation points when centered. Size of center platform has no influence on reachable area.
• Hmmm going through the code I'm becoming more convinced of the limitation.  To put it another way, I need my effector to be able to be beneath and "behind" the carriage.  The carriage is long, static.  The radius calculated is just the horizontal area under the rods.  I think I'm going to try overriding the whole thing and just setting it to what it should be given my setup and see if the rest of the math still works, but I'm not sure.  I'm adding some debug output to my printer to see if my understanding of the whole thing is correct.  I thought there used to be some good discussions about the variables, and how they were used, but it seems the search engines have been flooded with calibration procedures based on shoddy builds using endstops to correct for it.  Mine should be within .2mm everywhere in the worst case.  Just releveled the bed to be sure and its now to within 0.04mm.  I'm not a fan of adjusting the endstops, and I don't think that's the problem here anyhow!

• Ok, now I understand what you mean with long and limitations. That math is quite simple.

It assums effector as a single point with 3 rods going away from this in the angles you have. Using pythagoras it computes the height of the carriage position. On the other side of carriage it would be with one edge with negative value but everything gets squared so it can be computed. So just try slowly running in that area and see if it works. You would need to set max radius > horizontal radius to allow this. My printer can't even reach vertical position, so I can not test.
• I just had to dig into the code and see whats going on.  I had actually thought there was more to the code than there is. That's not to say its simple by any means, especially considering the wide range of printers supported.....I do kinda want to try and refactor some stuff and check the performance...ifdefs are great for performance, but annoying to read.  I'm a programmer for performance first, optimizing assembly code when necessary sacrificing all sorts of readability, but I do appreciate readability   Anyhow, I'm pretty sure I have it 100% now, and its much less a deal than I thought it was!