Brick Smoke Stack...out of wood! But what kind?

[CacheJunction]

The drawing is in Corel Draw. It is a vector object. I wondered about doing this, but I have only been able to stretch it symmetrically, if you know what I mean. I think I need to keep the drawing a rectangle since that is how the laser would raster the pattern, so it would just be the number of bricks per row and their length that would need to change. Do you know how to do this in CD? That would really help.

[peteski]

The drawing is in Corel Draw. It is a vector object. I wondered about doing this, but I have only been able to stretch it symmetrically, if you know what I mean. I think I need to keep the drawing a rectangle since that is how the laser would raster the pattern, so it would just be the number of bricks per row and their length that would need to change. Do you know how to do this in CD? That would really help.

I'm not a "laser guy" but I mess around with Corel Draw. Are all the mortar lines simply bunch of curves (lines)? Or is each brick a rectangle?  Are they grouped?  I also thought that you made the bricks uneven by burning a raster pattern on them?  Isn't that accomplished by assigning various gray levels to the areas?  I guess it would be helpful to see a sample.   Maybe a small part of the brick pattern?  I use Corel V 10.

Edit: I think that adding perspective to the pattern might accomplish hwat you are looking for.

[CacheJunction]

David, will your laser be able to auto focus as the surface moves further away from the taper? How will you keep it from going out of focus? Maybe there is something built into the rotary attachment to compensate for this? Curious minds want to know.....

The rotary attachment raises up on one end. With the simple tapered dowel the entire piece will be in focus. I use a leveling tool to check how much to adjust the tilt. What I worry about is when all the bricks get crammed at the top, the rastering effect will be much greater than at the bottom. If Scottl is right, distorting the image would solve this problem. But then again, maybe it isn't a problem! Now the beehive shape on the other stack, that will not all be on the same plane. I think there is some forgiveness in the focal length so, again, maybe this won't be a problem.

[CacheJunction]

I'm not a "laser guy" but I mess around with Corel Draw. Are all the mortar lines simply bunch of curves (lines)? Or is each brick a rectangle?  Are they grouped?  I also thought that you made the bricks uneven by burning a raster pattern on them?  Isn't that accomplished by assigning various gray levels to the areas?  I guess it would be helpful to see a sample.   Maybe a small part of the brick pattern?  I use Corel V 10.

Edit: I think that adding perspective to the pattern might accomplish hwat you are looking for.

You are correct about everything. The mortar lines are drawn in curves, then I fill each brick with a grey scale or texture which creates individual rectangles on top of the curves. Then I group it. So I guess yes to everything?

I have X6. Maybe tomorrow I can post a pic if it will help.

[peteski]

You are correct about everything. The mortar lines are drawn in curves, then I fill each brick with a grey scale or texture which creates individual rectangles on top of the curves. Then I group it. So I guess yes to everything?

I have X6. Maybe tomorrow I can post a pic if it will help.

Ok, group the entire pattern then apply envelope. and stretch or shrink whichever side needs t be changed.  Perspective is not the right thing (as it makes the "more distant" areas shorter vertically. Applying an envelope does not.

[CacheJunction]

Where is the envelope option? I'll try it first thing tomorrow.

[Alaska Railroader]

David, I also use CorelDRAW, X4. I hate to say it but I truly believe you are going to have to redraw your pattern to fit the taper. Otherwise your bricks will burn with an overlap at the smaller end and it will be deeper on the overlap exposing a defined seam. The shape on your workspace will have to be a trapezoid shape configured exactly to the shape of your taper. Even then it will overwhelmingly consume your time trying to make the pattern match up where it comes around to meet itself all along the seam. Even with perfectly machined dowels this would be quite a feat. Am I correct in assuming that you are able to keep the dowel perfectly parallel with the laser head and the rail it rides on because you can lower one end?

If I am correct you will eventually come to the point where you'll ask yourself "Is it worth all this time and energy?!?!?" I'm not trying to rain on anyone's parade so for your sake I hope I'm wrong. But from past experience I think this will be problematic for you and you'll begin wishing you were working on something else. This is how I tackle a challenge. I'll go at it until the time investment completely throws off my schedule or I get frustrated enough that I'll want to go design something else.

I sincerely wish you the best of luck. Now go prove me wrong 

[peteski]

Here is a sample of a brick pattern with envelope added.

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[Alaska Railroader]

Peteski, did you print that out and roll it into a tapered shape? You'll find that the seam will make the bricks form a shallow V, they cannot curve to the taper if you use straight lines. All of the lines of bricks have to be curved so that they will come out straight on a tapered dowel. Print your pattern on paper and try it, you'll see what I mean, but make sure you are coning the paper to mimic the dowel.

[peteski]

Peteski, did you print that out and roll it into a tapered shape? You'll find that the seam will make the bricks form a shallow V, they cannot curve to the taper if you use straight lines. All of the lines of bricks have to be curved so that they will come out straight on a tapered dowel. Print your pattern on paper and try it, you'll see what I mean, but make sure you are coning the paper to mimic the dowel.

No I didn't actually try this - just thinking out loud.    But I do understand what you are saying (if the chimney was a flat piece to be rolled up after being engraved).

Maybe I don't understand how the rotary attachment works.  I expected the laser head to only move in the Y direction (up and down the chimney).  The X (around the perimeter) direction would be achieved by the rotation of the piece being lasered (um, I really don't like using laser as a verb). 

But I don't own any laser engraving equipment - just giving my 5 cents worth of brainstorming. 

[Alaska Railroader]

.......But I don't own any laser engraving equipment - just giving my 5 cents worth of brainstorming. 

See, I love brainstorming when it comes to designing and then trying to figure out how to make the designs actually happen. You are pretty good for not being a laser guy I might add 

[peteski]

See, I love brainstorming when it comes to designing and then trying to figure out how to make the designs actually happen. You are pretty good for not being a laser guy I might add 

Thanks Karin!  I do some machining (both lathe and milling) and I design and print decal artwork, so I sometimes have to deal with stuff like this.    The stretched envelope-based design is not perfect either as the bricks have trapezoidal shapes. But I figured that in N scale that might not be noticeable.

BTW, I learned about the gray-scale raster method of laser engraving from DKS.  He showed my his school bus drawing (I need it for yet another project I have lined up to work on).

[Scottl]

Peteski accomplished what I was envisioning.  If the taper was measured accurately, the envelope could be accurate for the change in dowel diameter.  I'm not sure this will actually work on the laser, but just a thought.

[tom mann]

If I understand this phenomenon, most people who do it don't think they are doing it, will deny they are doing it, even believe they are being helpful. David, I can't tell for sure, but I believe you are not doing it intentionally. And I don't think you are even aware you are doing it. So, I'll politely ask that you not respond on this or any other thread I start in the future.

David C, you need to clear this up with David K Smith.  He wasn't trolling, it is unfair to accuse him of it, and it is unprecedented that a member asks a long time member to not respond to threads.

Please fix this ASAP.

-Tom

[victor miranda]

someone carves up a dowl and asks for help.

a vaguely interesting thread....
until...

the first poster gets more help than he needs.
ooooof.  well I have read worse.


ok, CacheJunction, here is the deal.
No matter what you or anyone does,
It is extremely rare that one will not be able to find some one else
who has been there or done that.

the good news; you have help.

second bit of help and you didn't ask for this is the first post.
from my many years of experience of foruming....
A troll who is trolling with a post finds facts are hard to put in a post.
a better way to say that is a troll does not use relevant facts.

So when you find a post full of facts you don't like...
the post was most likely made by someone far worse than a troll.
the poster was likely to be an expert on the subject.

  you may want to think about why I am giving you advice about trolls.

victor