horst.w
Posts: 781
Joined: Fri Oct 17, 2014 5:00 pm

Re: Incorrect hole sizes

Sun Dec 06, 2015 5:45 am

You are welcome!

I do it also for my own advantage - it is learning by doing ... :D


H.

moraesgyn
Posts: 27
Joined: Sat Mar 21, 2015 6:45 pm

Re: Incorrect hole sizes

Sun Dec 06, 2015 6:22 am

Maybe we should open a feature request to fix this for everyone.

horst.w
Posts: 781
Joined: Fri Oct 17, 2014 5:00 pm

Re: Incorrect hole sizes

Mon Dec 07, 2015 4:24 am

Maybe helpfull, but I think the problem is well known.
If I remember right, Simplify has introduced the improvement of Horizontal Compensation with version 2.2.2 (or a little bit earlier) and I'am sure that they would do so, when it is as simple as we think.
An other question is why an object with a outside length of 33,50 mm - and shown right in the print preview !!! - is print out with only 33.10 or a near value but not 33.50 mm as expected. That's a difference of 1%. All settings are normal and other objects are ok. I don't understand it.
In the RepRap-Forum I have found a thread where someone says that it is not possible to build the value - 0.1 in a right digital way. It is only approximate like pi . Perhaps there is a reason cause the problem. An other reason may be that in GCodes doesn't exist an ARC-Command. Circles are always build by a numerous polygone and there existes a problem with the different diameters of the perimeter-circles for the inside and outside wall.
A lot of trouble and when one problem is solved two new problems are created. That's a Hydra.

If you want to write a feature request - it is your turn.

Best regards
Horst

corry
Posts: 15
Joined: Sun Sep 13, 2015 3:40 pm

Re: Incorrect hole sizes

Sat Dec 19, 2015 11:56 pm

Simplify3d does have a bug in this along with plastic shrinkage. It's not just with round holes. I didn't check the GCode for outside permimiters, but for inside permimiters GCode is generated centered over the radius. With a .4mm nozzle and the fact layers are wider than nozzle size, you could see .8mm inaccuracies, even in plastics which don't shrink much as is the case I'm seeing. I started by generating a calibration cube with many different sized holes in it expecting to have to enlarge holes in my model by different amounts based on diameter. When I measured each one, from 3mm to 22mm in .5mm increments, each was off by roughly .8mm! No difference in the larger holes. That's when I went to the GCode and found the problem. Then tested a 4mm square hole cut out of a calibration. Cube. 3.2mm! So no, simplify3d needs to treat inner perimeters as boundaries, not as the point at which to move the tool head!

Really frustrating since I've been using simplify3d for everything. All my new spools are dialed in in simplify3d. Was trying to fix a massive overextension in skein forge in ngen and couldn't seem to get the numbers low enough. After 10 calibration cubes with unsatisfactory finished I decided I'll just drill the damned holes. Stupid to use subtractive after additive but with the bug, what else can be done?

Ill work later on putting together a bug report with test cases, GCode highlighted, etc. this isn't a question as to whether the bug exists. It's there. 100% repeatable, unlike my previous reports. (Not sure how there are such intermittent bugs, but I know the pain of hunting them!). After finding many of my reports were like that, I started restarting simplify3d every time it did something that seemed like it was an obvious oversight! This one is not one of those though. Pretty cut and dry, easy to reproduce, easy to fix, etc.

corry
Posts: 15
Joined: Sun Sep 13, 2015 3:40 pm

Re: Incorrect hole sizes

Sun Dec 20, 2015 12:26 am

Oh, and after the bug fix, can we also get the fix for the arc problem (inside of the arc doesn't need as much material as the outside)? Hopefully something a little more than skeinforge' cryptic parameters that require googling to figure out. Right now I wish I hadn't stopped with skeinforge. Such a pain to use, but once you get good with it, it makes amazing prints!

JeremyV
Posts: 1
Joined: Sun Dec 20, 2015 2:10 am

Re: Incorrect hole sizes

Sun Dec 20, 2015 2:47 am

has this issue been fixed or are we all still stuck dealing with off size holes? I just printed a 1inch square and it came out 1.006 by 1.003 it was only .100 high it has a .500 hole in it in the drawing but came out .475 by .470 so far I have fixed holes by doing test prints and ajusting the size in my drawing but that gets old quickly. let me know if anyone has figured out a good way to make this compensation.

corry
Posts: 15
Joined: Sun Sep 13, 2015 3:40 pm

Re: Incorrect hole sizes

Sun Dec 20, 2015 12:25 pm

Nope, not fixed. I have the latest version. It draws inner perimeters right on the line, not just outside it by extrusion width. There's some depositing of material in the inside of the arc, but that doesn't account for square holes. There's also plastic shrink, but if the outside dimensions are correct, scale and compensation won't fix it.

I too have been adjusting my designs. Really stinks when you only have stls!

Fred B
Posts: 30
Joined: Thu Jan 22, 2015 7:07 pm

Re: Incorrect hole sizes

Sun Dec 20, 2015 8:33 pm

From a shrinkage standpoint Simplify (and any other slicer) is going to have a hard time nailing down that last little bit of accuracy. The materials just vary too much even batch to batch or between colors.

The hole size issue with the Gcode generating on the center of the edge is news to me. I'm trying to think if another setting that could be causing this. Like gap fill or something? Print outside in or inside out?

Maybe I'll design up a little test print to check and experiment a little this week and during shutdown.

CompoundCarl
Posts: 2005
Joined: Wed Aug 05, 2015 7:23 am

Re: Incorrect hole sizes

Mon Dec 21, 2015 6:18 am

It doesn't generate gcode on the "center of the edge". Do a simple test model and take a look at the gcode. It's exactly where your model tells it to be. The extrusion traces the outline of your model perfectly. The bigger issue is that since people are representing holes with triangles, your circle ends up looking more like an octagon. And as you can imagine, that will have a smaller inner diameter that a circular shaft can fit into.

Using a higher STL export tolerance made this problem virtually go away on several of my printers.

corry
Posts: 15
Joined: Sun Sep 13, 2015 3:40 pm

Re: Incorrect hole sizes

Thu Dec 31, 2015 7:38 pm

Yes, it positions the *TOOL* *EXACTLY* where the model defines it. Plastic comes out *BOTH* sides of the nozzle. Place a 3mm hole in an object at 0,0. Note the min/max x/y are at 1.5 and -1.5. With an extrusion width of 0.48 holes will now be a maximum of 2.42mm. Add in the arc issue and it's less. Add in a bit of plastic shrinkage it's less. By for though the largest contributing factor is the extrusion width! Seriously, it's not rocket science and needs fixing!

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