I just got the glue line rip blade and I did a comparison in soft and hard woods with the CMT 50-tooth FTG think kerf I had been using for cross and rip cuts (and which is virtually new).
I was amazed when the CMT combo blade produced much smoother cuts in both the cedar and the maple. The Freud left very noticeable swirls, whereas the CMT left very minimal swirls. The Freud certainly cut with less resistance, but I used the same feed rate (approximately), same featherboard, etc. So what gives? Why am I getting a smooth finish on a combo blade and a fairly poor finish on what is billed as a “glue line” blade? Saw was just recently aligned.
CharlesM, if you are out there can I get some feedback? What about blade height? I hear some say to run the blade high so that the teeth are cutting more perpendicular and downward.
JH
Replies
"The Freud left very noticeable swirls, whereas the CMT left very minimal swirls." You shouldn't be getting any swirls with either one of these blades, so I suspect there's something out of alignment with your saw. I use a Freud combo blade, approaching needing sharpening, and a Freud Diablo rip blade, and neither one of these produces any swirls if I feed right and my saw's tuned up. At least not easily visible to the naked eye. I might get a few with the Diablo blade, but the combo blade leaves clean edges.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
The CMT left a very clean finish, minimal swirls and not enough to need cleaning up for gluing. The Freud left swirls much more visible and in need of cleaning up.
The saw is aligned to within .002 to both the fence and the mitre guage slots and there is no runout, so it isn't the saw (and the CMT result indicates that). The only advantage of the Freud (from my limited use) is that it requires less feed pressure and didn't burn at all in the maple, though the CMT didn't either, but has on occaision depending upon feed rate and thickness usually.
Morning O C..
I run CMT and Freud 24 T rip blades and don't get swirls. Raise your blade so the bottom of the gullet is just clear of the top of the stock to see if that helps. I rip a lot and this is my normal procedure as opposed to just exposing a tooth. Since I run a crown guard on top of the splitter, the more exposed blade is not a safety issue for me.
Regards...
Sarge.. jt
"...The Freud left swirls much more visible and in need of cleaning up."This suggests to me that something's wrong...whether it be the blade or settings....or you just have a different view of an acceptable edge than others do.
"whether it be the blade or settings." Or technique. It doesn't take much to get swirls with any blade.
When I'm out in the shop today, I might rip a piece of maple and a piece of poplar and take some pics.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Your CMT combo blade is a fairly high quality blade. It also has 50T vs 30T on the GLR. If quality levels are comparable, the higher tooth count typically equates to the cleaner cut, but usually at the expense of bogging in thicker materials and more tendency to burn. Even though the GLR is capable of glue line cuts, it won't defy physics. Most good 40T to 60T combo and general purpose blades are also capable of glue line cuts...the GLR is clean cutting for a ripper but it's still a rip blade.
Charles will likely have more insights about the proper use and height requirements of the LM74.
Edited 3/10/2007 8:11 am ET by Knotscott
Actually your theory about the CMT being able to give a better cut because it has more teeth is flawed.
The CMT, being a combination blade, has a combination of alternating top bevel teeth and flat top rakers. So in reality, on the side of the blade that is actually cutting the edge of the board in question, only half of the teeth are cutting, plus the rakers. This makes 30 teeth cutting that board edge.
On the glue line rip blade, all of the teeth are cutting, so in reality there are essentially 30 teeth on the cut edge of the board.
If he were using a 60 tooth ATB blade, there are still only 30 teeth cutting each side.
PS Freud does make really good blades, as good or better than CMT in my opinion.
Hal
http://www.rivercitywoodworks.com
"Actually your theory about the CMT being able to give a better cut because it has more teeth is flawed.The CMT, being a combination blade, has a combination of alternating top bevel teeth and flat top rakers. So in reality, on the side of the blade that is actually cutting the edge of the board in question, only half of the teeth are cutting, plus the rakers. This makes 30 teeth cutting that board edge. On the glue line rip blade, all of the teeth are cutting, so in reality there are essentially 30 teeth on the cut edge of the board. If he were using a 60 tooth ATB blade, there are still only 30 teeth cutting each side."Hi Hal - I understand the theory you're trying to point out, but I don't believe it's correct. The tips of the ATB teeth make the equivalent of a scoring cut, where indeed only every other tip is engaged with the scoring portion of the cut. This pertains to the entry side of the cut, but the edges of all the teeth still contribute to the quality of the resulting edge cut. The GLR is a TCG grind which uses a combination of chamfered teeth and flat teeth. If your theory was correct, then the chamfered teeth aren't contributing to the quality of the edge at all, only the flat teeth would be, which would mean only a fraction of the teeth were contributing to the cut quality but I don't believe that's an accurate description of how the teeth are actually working in the board.
Edited 3/12/2007 2:22 pm ET by Knotscott
I also use the Freud LM72 Heavy Duty Rip blade and normally get glass smooth cut surfaces. I rip mostly maple +/- 2", and occasionally some red oak. No trouble with either material. Rip and glue. Maybe it's a lack of experience on my part but the the Freud has been the best rip blade I've ever used.
Jeff
I took the time to rip a couple of test cuts tonight before leaving the shop. Used a 24-tooth Diablo rip blade on a piece of 3/4" poplar, and a Freud 50-tooth ATB combo blade on both poplar and maple. The maple was closer to 1" thick.
Except for one small place where I paused and adjusted my hand, there were no tooth marks using the combo blade. The rip blade left a few, but not very visible, half-swirls.
Somethin' going on here besides the blade. One thing that can get out of adjustment and not be noticed is the splitter. If it's not quite in line, or not 90° to the table, it can nudge the stock and create problems at the blade.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I have a old Craftsman contractor saw but it is tuned fairly well. I was using a Freud thin kerf combination blade (Diablo?) and was very satisfied. It only required a occasional touch up of the rip edges with my jointer.
Then there was one of those Amazon sales on the Freud GLR. The GLR blade produces edges that look so good, it made my jointer look a mess. I brought another jointer, but for face jointing only. There is no need to edge joint in my shop.
Maybe I'll be a little disappointed when the GLR has been used as much as the Diablo, 3 years.
-Joe
Joe, I like Freud blades. I have no complaints whatever about the quality of the cut left by my Freud full-kerf, FTG ripping blade and have found the Diablo combo blade to perform equal to blades twice as expensive. But there's something wrong when a blade, any blade, produces a better surface than a jointer, any jointer. Something's wrong with that jointer. If the bearings are good, any jointer, once it's adjusted properly, with sharp knives, should always beat a blade for jointing an edge. Rich
"any jointer, once it's adjusted properly, with sharp knives, should always beat a blade for jointing an edge." Admitting my relative lack of experience with industrial machines, I'm still not so sure this is a Law of Woodworking. With the different kinds of grinds the tool companies put on saw blades these days, they can get the blades to act on wood in ways that might challenge a basic jointer blade (ignoring the helix-types for the time being). They can shear, they can polish, everything but serve coffee. Would like to get Charles M's input on your statement above.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Wow Forest Girl, I'm suprised to hear you say this.
There is no possible way in the world that a saw blade can cut as well as a jointer. The saw tears away the wood. The jointer cuts it like a rotory hand plane.
Of course you are talking about the best possible saw blade, cutting wood on a perfectly tuned saw. So to be fair, you would have to use the same criteria for the jointer.
If someone's jointer isn't doing a better job than their saw, they need to spend a couple of minutes and tune the jointer.
Hal
http://www.rivercitywoodworks.com
>> The jointer cuts it like a rotary hand plane.Of course, and there-in lies the fallacy. Rotary motion creates a scallopped surface in the board being jointed. There is no way around this scalloping with rotary cutting jointers or planers. But, a good blade cuts a flat surface if it is properly adjusted. A blade with minimal side cut like the new Freud or the WWII will burnish the kerp giving an even smoother, almost polished, surface.Now, in spite of the above, perfect surfaces are not necessary for perfect glue lines. Slight blade marks will not cause glue lines to be any more visiable that those that come off a jointer or a premium blade if proper clamp pressure is use. Most of the custom shops I am familier with go directly from the saw to glue-up.Howie.........
Yes, this is my experience both practically, and logically. There is no way for a rotary jointer to do anything but leave a wavy surface (how many cpi depends on the rpm and feed rate). Lots of tiny waves but waves nonetheless. I have never had a problem gluing up when using a 50T combo blade.
FG,What Hal said.I really want my saw blade to serve coffee!But as far as preparing a jointed edge, the blade is chopping across the fibers and tearing them, although the blades now also burnish the surface, making it smooth. I don't think that's really a good thing for a glue joint.While even a machine jointer can't prepare the ultimate joint, that's the provence of a jointer plane, it still shears fibers in the direction of the grain. And that's the best way to get the surface smoth, with intact fibers ready for gluing.Rich
I would love for all of our members to go out and joint an edge, then examine it under a magnifying glass. Look for the ripples. That should tell us now many, percentage-wise, have a perfectly tuned jointer. Not very many, I suspect.
OK, so what's the perfect edge for jointing? Please describe...I'm sincere in this request. Yes, I realize that a shiney, burnished edge is not a good thing for glue. That's why I don't use my best crosscut blade for end-grain that's expected to hold some glue. But what kind of edge surface is best?
I've confessed I don't own a glue-line rip blade. Never saw a need for one -- my saw produces a pretty fine edge, and if I screw up feeding for a rip and get some light burning or swirl marks, it can be jointed on the Jet 6" jointer. But the good edges (the non-screwups, as it were) look fine for jointing, as long as they're also straight and 90°.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
FG, The "glue line" ripping blades produce surfaces ready for gluing. I don't know how much better a joint would test under destructive testing, but a jointer plane, followed by a properly tuned jointer does a better job. I can't quantify the diffrence. Rich
You are correct about the jointer Rich. That jointer was replaced.
-Joe
JH,
As a rule, the blade should be set so that 1/2 of the highest tip is above the material. Also, how thick is the stock you are ripping and are you using a splitter?
Freud America, Inc.
Thanks Charles, I've been intending to run some more cuts to play around with settings and such, but due to work haven't had a chance to get in the shop. I set the blade high since some say you get a cleaner cut due to the orientation of the teeth to the kerf. I'll run some through w/ the blade set low.
I am using a splitter (and featherboard) and I was ripping 5/8 maple and 1.25 thick red cedar. But I didn't take the time to make a thicker splitter for the full kerf freud (over the thin kerf CMT). That may account for something as well.
Thanks for the feedback.
You all can have your theories, but all it tells me is that you need to tune your jointers. If they are precision machines and you set the knives to within 1/1000", and you cut off less than 1/32 at a nice slow feed rate, you will not be able to see any cuts at all. And there will be absolutely no tearout on the edge of the board like your saw leaves.
Research has shown that the best gluing surface is obtained by having a freshly cut surface, cut by a jointer, with the surface having 25 to 27 cuts per inch.
I think it is Bruce Hoadley that states this in his book Understanding Wood, although I could be wrong about it being him. It's been at least 25 years since I read it, maybe 30.
The only case that I know of that this isn't true is if the wood being glued is white oak and it is being glued with epoxy. Then the roughness of the saw cut is a better surface for the glue to grip to.
Also, the rip blades I use have square tips. I assumed that the blade we were talking about was the same. I personally don't consider a triple chip blade to be a rip blade. They cut well, I have used some really high quality industrial ones, but this isn't their traditional use as far as I know. I also use a square-tip 50 tooth, thin kerf combination blade that essentially cuts like a 100 tooth blade. It is awesome! But it won't cut as cleanly as my jointer.
Hal
http://www.rivercitywoodworks.com
With respect, you are citing 20-25 year old information in regards to glue joint strength. The conclusion may still be valid to a degree but the comparison is no longer the same due to advances in saw blade technology. IME, there is negligible difference between a proper rip off the saw and a jointer in terms of glue joint visibility and strength. OTOH, the jointer does excel at truing up edges (and faces) of the material so it still has a place in the shop.
Charles M
Freud America, Inc.
I'm still using the same jointer and the same glue.
The whole thing probably depends on each person's opinion of what is good enough. In my case, a saw cut joint is not good enough. For some it may be.
Hal
"I'm still using the same jointer and the same glue. "
And the same saw blade? ; - )
Mike HennessyPittsburgh, PA
Nope, I still use everything from industrial blades like Leitz and FS Tool, to off-the-shelf Freud, Systematic, and CMT.
My blades work as well as yours. By using a jointer I can cut and joint a large panel of long boards and always get excelllent results and a flat panel.
You are welcome to do it your way. If it works well enough for you, fine.
Hal
http://www.rivercitywoodworks.com
Hal,I certainly won't try to convince you not to use the jointer. The results you get show in the high quality of your work.
Charles M
Freud America, Inc.
Hi All,
To me, the actual surface of a glue joint isn't,t nearly as important as straightness. I just love to hear that little snap when two perfectly straight boards are pushed together. It's the jointer, hands down, that makes that happen for me.
Paul
On long boards being glued up for a panel I actually prefer them not to be perfect straight. I like a little daylight in the middle of the joints so when I clamp it pulls the center together.
This allows for one or two clamps to hold the assembly rather than 5 or more. Also, when the endgrain dries out years later it won't check at the ends.
A little trick on old timer that's now dead taught me.
I do this same thing, but if you really think about it, it takes more clamps to pull everything together tightly with a gap in the middle. It would take fewer clamps if the joint was cut the other way around. In fact, if the spring was perfect (away from the joint at the ends), you would only need two clamps, one at each end.
This means absolutely nothing. I know that a joint should never be cut this way so please, please, please don't write to tell me that I am stupid! I am just saying that it would take fewer clamps. If anyone writes to say anything in reply to my message we will all know that you aren't paying attention and we will all be laughing at you behind your back! Go on, I dare you.
Hal
http://www.rivercitywoodworks.com
Hmmm...I've actually clamped whole panels with one clamp using the "spring" method I described. One clamp right in the middle pulls all the planks together.
I'm old fashioned, still using two clamps, one at each end. But I've found a way to save glue - I only glue each end and leave the slight bow open in the center.
That way when we put the tablecloth on, I clamp the center and it pinches it so it doesn't fall off!
:-) :-)Bob @ Kidderville Acres
A Woodworkers mind should be the sharpest tool in the shop!
Great idea! I think I will stop using duct (duck?) tape!
:) :) :)
A bad day woodworking is better than a good day working -- yes, I'm retired!
Try a splitter.
Also, it seems rip blades are usually thinner than combo blades so sometimes I get a little wobble in my rip blades if I feed fast.
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