"Region" Question

[heyward43]

I'm using designer to design a fairly simple project but have a question about the region tool. If I draw a rectangle 1" x 2" in designer (depth whatever) is the resulting cut exactly 1" x 2" or is it 1 1/16" x 2 1/16". The graphics seem to draw it correctly in some cases and incorrectly in others. If you look at the project file (included) I started designing on the back of the board. The center rib should be 1/4" x ??". The rectangle is correct but the graphics look like it is 3/8". Compare to the next rib at 1/8" which looks correct. Any answers? Thanks

[hotpop]

I can't imagine what this thing is.

I looked at it from the end and I think your front cuts are cutting into your bottom cuts eliminating material from your bottom.

Maybe go through all your dimensions again.

[AskBud]

Heyward,
Check each one using the "White" boxes, it may be much easier.
AskBud

[AskBud]

Here is what Hotpop saw.
AskBud

[heyward43]

Whoops! I think I sent the wrong version. It is basically a step pyramid and should look like it from the end even though it's about 23 inches long. The region issue was causing me some drawing problems. I think I've figured out the "region" tool. Basically, the white line is the center of the cutting bit. Therefore the actual cut line will always be 1/2 of the cutting bit diameter outside the white line. Tell me if I'm wrong so I don't have to do it all over again for the fourth time. I'll send a file of the corrected version as soon as I finish it. Thanks to all.

[AskBud]

Whoops! I think I sent the wrong version. It is basically a step pyramid and should look like it from the end even though it's about 23 inches long. The region issue was causing me some drawing problems. I think I've figured out the "region" tool. Basically, the white line is the center of the cutting bit. Therefore the actual cut line will always be 1/2 of the cutting bit diameter outside the white line. Tell me if I'm wrong so I don't have to do it all over again for the fourth time. I'll send a file of the corrected version as soon as I finish it. Thanks to all.

A Carve Region is a "Closed" figure, and you have no choice of bits. It will be with the Raster. and should be the dimension you select. The only exception that I know of is the newer version(s), 1.150 in particular, give you the option of a feather being inside that dimension or outside if you wish.

A Vector cut, straight or curved is one that carves down the center of the line.

You can best see these effects when you display grid lines, as you can line up a particular figure and see it in relation to the grid.
AskBud

[bergerud]

I think that the size of the carved region will depend on bit optimization. With no bit optimization, each edge will be 1/32" larger than you drew and the sides will of course be sloped. It you choose bit optimization best, I think it will be the size you want with the sloped sides.

[AskBud]

I think that the size of the carved region will depend on bit optimization. With no bit optimization, each edge will be 1/32" larger than you drew and the sides will of course be sloped. It you choose bit optimization best, I think it will be the size you want with the sloped sides.
Test that theory and let us know how you progress with each setting.
AskBud

[bergerud]

I am glad you asked Bud. I have not carved them but take a look at these 10 1/2 by 1/2 inch squares. The top row of 5 squares are all carve regions with bit optimization none to best left to right. They appear to be all the same. The lower set of squares are 1/2 by 1/2 inch bitmaps with bit optimization none to best left to right. Bitmap shapes like this I have carved and measured. I would say the squares will carve from 9/16 by 9/16 on the left to 1/2 by 1/2 on the right.

It looks like I was wrong about the carve regions. Bit optimization does not seem to apply to them. I assumed bitmaps and carved regions were treated the same.

If we believe what we see, the carved regions will carve closer to 9/16 by 9/16. It appears that a carved region is simply where the center of the bit will cover. You will have to subtract 1/32 from each side. Note also that designer does not show the sloped sides of carved regions . (Changing the hole depth does not change the hole size.)

Bitmaps on bit optimization best are closest to what you measure is what you get.

I will carve these and report if there are any surprises.

[bergerud]

I carved the squares (on optimal) and measured the widths (up 1/32 from the bottom). All of the five carve region holes measured around 0.550. Not quite the 9/16 predicted but all the same size, proving that bit optimization, although selectable for these objects, has no effect.

The bitmap squares came in at

0.535 0.530 0.530 0.510 0.505
where the bit optimization is from none to best. I am sure results will vary from machine to machine but the trend should be similar.

Another wish list item: Please connect the bit optimization algorithm to the carve regions.

[HighTechOkie]

Nothing wrong with the bit optimization, it is meant for raster patterns to optimize the Z not x or y.

CW/CC 101 the machine logic is such that the all dimensions are referenced to center of bit tip and NOT the outer diameter. If you want a carve region to be to an exact dimension, subtract 1/16".

Rob

[bergerud]

My understanding is that bit optimization is to help compensate for the geometry of the bit being a ball and cone. With bit optimization at best, the machine tries to have the carving be the envelope of the bit surface. The idea is that the bit does not, because of its size, cut too much. This involves calculating the z values of neighboring paths (involves x and y). At the sides of a hole, bit optimization stops the bit from cutting into the sides and so for a bitmap hole, the bottom of the hole will be carved the same dimensions as the bitmap. No need to subtract the 1/16.

When I make a complicated bitmap pattern, I do as you say, subtract the 1/16 up front. Still, it is nice to know that bit optimization can do this. And then, knowing this, one wonders why the carve regions are not affected selecting it. Either grey the bit optimization out for carved regions or apply it as for bitmaps.

Am I missing something here?

[Pratyeka]

If it calculate from the center of the 1/16" (dia) carving bit, then shouldn't you substract 1/32"?

[bergerud]

Thinking of a hole with two sides. 1/32 off each side.

[heyward43]

Thanks again guys (and gals). I think I'm getting a little confused. One thing I do get is that the carve region will only let you use the 1/16 carving bit. That's not what I want. Therefore I will use the 1/8 cutting bit because I need straight sides and flat bottoms. Which means that I will be doing a rout instead of a carved region. That means the white line represents the center of the bit so therefore the 1/8 cutting bit will cut 1/16 on each side of the line. One other problem I see is that in my redesign for the 4th version even though I do a rout and specify the 1/8 cutting bit the designer draws the picture as though I was using the 1/16 carving bit (ie. the sloped sides). I think this is what is throwing me off. I think that once I carve this with the 1/8 cutting bit it will come out as I want it to look not as it looks in designer. Personally I think the drawing should reflect the shapes of the bits that are specified. I think I will try this on a scrap piece of wood and do a shorter version to test it out. I uploaded the full cut out and it calculated 10hrs and 50mins. I don't want to mess up a good piece of wood and waste a whole day with a bad program.

[heyward43]

I forgot to attach the current design. If you will rotate the figure and look at the right hand end of the board you will see what I mean about the drawing looking like it is using the 1/16 carving bit (see the fins sticking up on the top and next lower levels). There isn't a fin on the lower level because I think the cutout pass trimmed the fin off. Those slanted fins shouldn't be there if the cut was drawn with the 1/8 (straight) cutting bit. Or at least they would be straight up and down. What do y'all think?

[bergerud]

It appears to me that your carving does not even use the carving bit you select for the board. All your cuts are from selecting bits on lines and rectangles. Designer is not always what you see is what you get. Don't take the graphics too seriously and do a small test carve.

[heyward43]

Thanks for the info. You would think that the drawing would be a little more accurate than what I see. To me it makes me think I am doing something wrong. I guess I'm too much of a perfectionist. I will do a test cut on a much smaller version of the project tomorrow. One other question somebody may have an answer for. If I draw a line segment (ie. straight line) and specify a 1/8 straight bit what is the direction of the cut. Will it be back and forth across the Y axis as for a carving or will it be along the X axis in a single pass. The reason I ask is that the time calculated to carve a project with only straight lines was calculated at over 10 hours when in my view if you are only cuting straight lines along the length of the board the time should be a lot less than 10 hours.

[bergerud]

My machine said 4 and a half hours on best. The cut paths along the paths. The x direction in your case. You have many and also many passes per cut so it will take awhile. Good luck.

[AskBud]

Look at the back of the board.
You will see lots of carve areas (rectangles) that will take most of your time. These carves will be made across the width of the board, moving the lenght of the board, about 6/1000 at a time just like carving a picture/pattern.
AskBud

[bergerud]

Bud is right, I thought you had all route paths. You can probably change these carve regions to route paths since the rectangles are so narrow. I quickly converted them and find the time to to be around 2 and half hours. Glad you are watching Bud.