Quick Question About Kerf?????
11-03-2011, 10:05 AM
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Quick Question About Kerf?????
Ok I want to send some plans to the Laser cutter on DXF, so he can set them up to cut. Say I have a wing rib or former that I need slots for 1/4 X 1/4 wood. The cutter tells me his cutter leaves a .08 kerf. So to get my slots for a snug fit, I would acutually make the size of the slots in the rib or former .246" X .246" yes or no??/ if not tell me why.
11-03-2011, 11:13 AM
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RE: Quick Question About Kerf?????
I'm guessing you meant a .008" kerf since I can't imagine a laser that cuts an almost 3/32" wide swath! 
Simply draw the part exactly as you want it, i.e., with 1/4" slots and then offset the entire part by .008". Since the laser will be removing the same amount of material all the way around the cut you need to offset more than just the notches if you want a truly accurate part.
Simply draw the part exactly as you want it, i.e., with 1/4" slots and then offset the entire part by .008". Since the laser will be removing the same amount of material all the way around the cut you need to offset more than just the notches if you want a truly accurate part.
11-03-2011, 12:34 PM
#3
RE: Quick Question About Kerf?????
"Kerf" normally describes the small gap in the part outline, that keeps the parts from falling out of the sheet.
Just draw the parts to the actual size, the laser beam is very small, say .005" and much less when it exits out the bottom of the sheet, as the cut is tapered.
That is, if the laser cutter knows what he/she is doing.
Bob
Just draw the parts to the actual size, the laser beam is very small, say .005" and much less when it exits out the bottom of the sheet, as the cut is tapered.
That is, if the laser cutter knows what he/she is doing.
Bob
11-03-2011, 01:36 PM
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RE: Quick Question About Kerf?????
Thanks fellas, I just didn't want them to be oversized to much. Heck I can do that myself with a scroll saw.
11-03-2011, 02:49 PM
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RE: Quick Question About Kerf?????
Puff,
I do quite a bit of laser cutting and I find that .005" offset allows for nice, snug fits on slots and tabs for just about any kind of wood we use in modelling up to about 1/4" thick. My .02 cents worth.
I do quite a bit of laser cutting and I find that .005" offset allows for nice, snug fits on slots and tabs for just about any kind of wood we use in modelling up to about 1/4" thick. My .02 cents worth.
11-03-2011, 04:38 PM
#6
RE: Quick Question About Kerf?????
As a professional wood worker, it is the responsibility of the machine operator to create an accurate part to your specs. Any tool offset is the concern of the operator not yours.
One thing I would like to point out. Have your cutter leave the parts in the sheets for safe shipping. They can hesitate the laser in spots leaving a very small tab to keep the parts from falling out of the sheets. I am pointing this out because I just recieved a very large kit from a cutter and they shipped all parts in bags already removed from the sheets. Almost all of my formers were broken. Any where short grain was present, the part broke. I literally had to glue all of these back together after finding all the parts. Just an FYI
One thing I would like to point out. Have your cutter leave the parts in the sheets for safe shipping. They can hesitate the laser in spots leaving a very small tab to keep the parts from falling out of the sheets. I am pointing this out because I just recieved a very large kit from a cutter and they shipped all parts in bags already removed from the sheets. Almost all of my formers were broken. Any where short grain was present, the part broke. I literally had to glue all of these back together after finding all the parts. Just an FYI
11-03-2011, 05:43 PM
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RE: Quick Question About Kerf?????
ORIGINAL: vertical grimmace
As a professional wood worker, it is the responsibility of the machine operator to create an accurate part to your specs. Any tool offset is the concern of the operator not yours.
One thing I would like to point out. Have your cutter leave the parts in the sheets for safe shipping. They can hesitate the laser in spots leaving a very small tab to keep the parts from falling out of the sheets. I am pointing this out because I just recieved a very large kit from a cutter and they shipped all parts in bags already removed from the sheets. Almost all of my formers were broken. Any are where short grain was present, the part broke. I literally had to glue all of these back together after finding all the parts. Just an FYI
As a professional wood worker, it is the responsibility of the machine operator to create an accurate part to your specs. Any tool offset is the concern of the operator not yours.
One thing I would like to point out. Have your cutter leave the parts in the sheets for safe shipping. They can hesitate the laser in spots leaving a very small tab to keep the parts from falling out of the sheets. I am pointing this out because I just recieved a very large kit from a cutter and they shipped all parts in bags already removed from the sheets. Almost all of my formers were broken. Any are where short grain was present, the part broke. I literally had to glue all of these back together after finding all the parts. Just an FYI
If the operator is doing the drawings, then he wouldn't have to tell the consumer the Kerf. In this case I believe it is the consumer that is supplying the cut file. It is up to him to understand what tolerances are required to get the desired result. Prepping the drawing for cutting is time consuming and expensive. Most people save a few bucks by supplying their own drawings, so it it really isn't cutters responsibility. That being said, .005 is a reasonable kerf. My older machine (25W Epilog Radius) was about .010. That was the thickness of the cut. I divided that by 1/2 and used a .005 offset. Remember, if the cut is .008 wide and the laser is cutting on the line drawn, then .004 is on one side and.004 is on the other.
11-04-2011, 06:13 AM
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RE: Quick Question About Kerf?????
"As a professional wood worker, it is the responsibility of the machine operator to create an accurate part to your specs. Any tool offset is the concern of the operator not yours. "
Looks great on paper, but Rotsa Ruck. Several that I have delt with in the past either send you to their "recommendations" , or just cut what you send. The cutter has no real way of knowing what the "true" size of what you want is, except by what you send, unless all the parts are dimensioned.
Les
Looks great on paper, but Rotsa Ruck. Several that I have delt with in the past either send you to their "recommendations" , or just cut what you send. The cutter has no real way of knowing what the "true" size of what you want is, except by what you send, unless all the parts are dimensioned.
Les
11-04-2011, 07:03 AM
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RE: Quick Question About Kerf?????
Is the software for these laser cutters not capable of offsetting for the kerf? When I program to cut on a CNC machine, I have contour (outline) cuts to cut on the left side of the line, cutting clockwise around the part. The program knows the diameter of the cutter, so knows how much to offset the cut to stay outside the line.
I would consider having to manually adjust the drawing to allow for offset to be a MAJOR PITA in this day and age.
I would consider having to manually adjust the drawing to allow for offset to be a MAJOR PITA in this day and age.
11-04-2011, 12:02 PM
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RE: Quick Question About Kerf?????
ORIGINAL: catspaw
Is the software for these laser cutters not capable of offsetting for the kerf? When I program to cut on a CNC machine, I have contour (outline) cuts to cut on the left side of the line, cutting clockwise around the part. The program knows the diameter of the cutter, so knows how much to offset the cut to stay outside the line.
I would consider having to manually adjust the drawing to allow for offset to be a MAJOR PITA in this day and age.
Is the software for these laser cutters not capable of offsetting for the kerf? When I program to cut on a CNC machine, I have contour (outline) cuts to cut on the left side of the line, cutting clockwise around the part. The program knows the diameter of the cutter, so knows how much to offset the cut to stay outside the line.
I would consider having to manually adjust the drawing to allow for offset to be a MAJOR PITA in this day and age.
11-04-2011, 12:06 PM
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RE: Quick Question About Kerf?????
ORIGINAL: limeybob
Hi, how do you offset for interior holes?
Thanks
Bob
Hi, how do you offset for interior holes?
Thanks
Bob
11-04-2011, 12:15 PM
#13
RE: Quick Question About Kerf?????
Hi, all this offset discussion is really moot for a laser.
.005 is nothing when compared to the thickness variations in the wood you might be cutting slots for , as well as the spars that will fit in the notch's you cut.
Just cut to size.
The only time I concern myself with a clearance issue is for the aluminum wing tube I use on my Jetmach design. I must be a tight fit. and any application like that.
Bob
.005 is nothing when compared to the thickness variations in the wood you might be cutting slots for , as well as the spars that will fit in the notch's you cut.
Just cut to size.
The only time I concern myself with a clearance issue is for the aluminum wing tube I use on my Jetmach design. I must be a tight fit. and any application like that.
Bob
11-04-2011, 07:56 PM
#14
RE: Quick Question About Kerf?????
I've been programming laser equipement for 20 years. "Kerf" is the thickness of the cut whether it be a laser beam or a punch tool. General rule of thumb for laser cutting is program left side kerf, G41, cut the outside perimeter of the part with thetool path CW and cut theinside profile (holes) tool path CCW. Limeybob is probably meant "Tab" not "Kerf".
Wish I could have a laser for home too.
Jim
Wish I could have a laser for home too.
Jim
ORIGINAL: limeybob
"Kerf" normally describes the small gap in the part outline, that keeps the parts from falling out of the sheet.
Just draw the parts to the actual size, the laser beam is very small, say .005" and much less when it exits out the bottom of the sheet, as the cut is tapered.
That is, if the laser cutter knows what he/she is doing.
Bob
"Kerf" normally describes the small gap in the part outline, that keeps the parts from falling out of the sheet.
Just draw the parts to the actual size, the laser beam is very small, say .005" and much less when it exits out the bottom of the sheet, as the cut is tapered.
That is, if the laser cutter knows what he/she is doing.
Bob
