Hello everyone.

Could anyone help me with trying to cut a perfectly straight diagonal line across a surface consisting of many faces. I have tried the knife tool but all I get is it creating an uneven line, essentially following my shaky hand. I have also tried reseting the "Type" of action and that just makes it worse. I know it can be done, it is just a case of trying to remember how.

Any help would be greatly appreciated.

Ian...

with not seeing the object in question its hard to say but splitting faces is not usualy a feature for blender

it can be done in retopo if you have the skills and patience

if it was a single loop you could use the shear option   in edit mode CTRL+S

without all details its almost impossible to say

You could also use a plane and a boolean modifier. It will make bad geometry, but the plane should act as a knife and achieve your goal.

I have tested the process using blender version 4.9a and it works but sadly not in the latest 2.59 version. The image I have attached should give a better idea of where the cut needs to be (Red line), and just to note that the proposed plane is not flat.

The process I followed in Version 4.9 was to click once at the beginning of the cut with the knife tool and then again at the end whilst holding down the "K" key. This gave a perfectly straight line.

With the amount of texturing that the model will need when complete "Boolean" is off the list of possibles because as you state it will create "bad geometry".

Hi Benney hows u ??  fairly new to blender so cant help much and had same problem with Knife tool (wobbly hands lol ) in gimp I have got straight lines using my tablet and a ruler but dunno if blender works well with a tablet and cant test cos me lads "borrowed" mine lol

  There's an addon called "fake knife" which has worked on again and off again throughout the 2.5 versions. It seems similar to the 2.49 knife. Currently it appears to be working(in blender v2.59).

  I recommend downloading a build from Graphicall.org which has addons_contrib included, as you might find more utilities useful to you therein as well.

 

 For just the fake knife addon:

http://wiki.blender.org/index.php/Extensions:2.5/Py/Scripts/Modeling/Fake_Knife

 

hope that helps

I am also still a newbie to blender but learning quickly. It has even taken top place between "Hexagon", "Carrara" and Blender. One day I will be going into creating full scenes and then animation (but that is a long way to go yet.)

Thanks for the link. I will check it out and I am always on the look out for extra modelling addons. You never know when they come in handy.

i think i have the idea of what you want to do

if this is the basic finished piece you want i can write a short tutorial here for it or

just add a plane and set it to the angle and area you want it at then select the cylinder and TAB into edit mode and use wireframe and select the verts and G to rab and X to stay on the Xaxis and make the cut

 

Any chance of a small tutorial as I can't seem to fully understand the process you have noted. Call me thick if you wish (Grin!).

for a tut it would take a bit i have several ahead of it for now

as for a video based that would be faster but a bit hard to understand due to my accent

and i am targeting my tutorials to the novice to blender that hate videos so it takes more time and as it is that i am just learning 2.5+ myself its a bit slow

ill work it in

 

Take your time my friend. I have several other projects develping myself also, so I can spend the time on them until you kindly put forward the tutorial.

I think what he means is to load a plane as a guide then grab each vertex and move it into position (snap will make it quicker )

 

another way it might work is if you know the angle, rotate the part to that angle and use scale (axis) 0  to bring it flat then rotate it back into its final position

Ah.. I see it now.. Not such an easy job when the surface that needs to be cut is slighly sperical... But I'll give it a go and see what happens.

Attached Link: Modeling a Smooth T-Joint Connection in Blender

I think you guys are going about this the hard way. I think the tool you may want is the "shear" tool [**ctrl+s** in 2.49 | **ctrl+shift+alt+s** in 2.5x] Given the information and pictures provided thus far anyway, there is/are situations when the shear tool wouldn't work as well or would require other tools to be used in conjunction with it, but I've seen nothing to suggest this is one of those cases.

Anyway, here's a quick tut I three together, hopefully it kinda gets you headed in the right direction, also attached a link to a video tut from Kernon Dillon's Vimeo page, in which he uses the shear tool.

[Step 1] You've got your cylinder like shape, if its capped the way mine was, you want to select the center point first, so you can use the "cursor to selection" function from the snap menu [shift+s] to snap the 3D cursor to that point, altenatively, if you don't have a point in the middle, select the one/two points that would allign with that point, and snap your curso to them instead. Once your cursor is accurately positioned, continue selecting the rest of the points you want to shear.

[Step 2] Make sure your "pivot center" is set to "cursor" the activate the shear tool [ctrl+shift+alt+s]. Move the mouse left/right until it aligns with your background image.

[Step 3] That's all folks. No nasty boolean/knife/cut operations, keeps all quads.

[Click to see larger]

 

One note, give the amount of geometry you have, you'll either have to repeat the shear tool multiple times selecting each row of points, say, one unit for the first loop, two units for the second loop, three units for the third loop, until you get to the amount you need to shear end to match your refrence. The better method to affect multiple rows of points such as you have, would be to use Blender's "proportional editing" / fall-off, unfortunately, I find that horribly awkward to work with.

Hope this helps a little.

i did mention the shear option but looking more at the image provided there was a loopcut that would have made shear impossible

and i am not the guru of the 2.5 version because i still preffer the 2.49.2 interface

but it is a workable method that will greatly reduce the work flow

 

Loop Tools Add-On contains Flatten, which has quite a lot options. It can be used to make vertexes go along your cut (see image).

Another possibility is to insert a plane and then use snapping to move vertexes to that plane. Kind of handmade Booleans... :)

I think Doomsday's got the right method, that's pretty nifty, nice and clean too.

Unroken, sorry, I missed your mention of the shear tool, I must have skimmed over that. I use 2.5 regularly, but not for modeling, [haven't done any modeling in Blender since 2.45 or so, which I was using regularly up until last fall] 2.5 just did my head in trying to figure out how to get the loop cut working!

Were if not for the tool Doomsday pointed out, I maintain shear tool would be the way to go, those other loops, as much as I can tell from the images supplied, aren't relevant to anything, so you could...

a] add them after you did the shear [probably what i'd do]

b] you can just use the shear tool once on each loop so that they're clear of the last loop [what I did below].