Straight-Line Rip Saw Operation
An extended discussion of safety and operating technique for straight-line ripsaws. May 28, 2006
Question
I'm thinking of going ahead with a SLR saw in the coming year, but have a few questions about how to get the most out of it:
Can it eliminate edge jointing? It seems like some boards have enough internal tension that they bend towards or away from the kerf after ripping. Am I going to want to keep an edge joint step for rail and stile parts?
Crosscut first or SLR first? Or does it just depend on the situation, stock quality? How do they handle rough stock? I sometimes get a unit of rough instead of H&M. It seems like there is so much power in these saws that binding due to warp or twist shouldn't be an issue?
Can a dedicated machine like this completely replace my table saw for ripping, or are there times when a table saw nearby would be helpful?
Are there a variety of blades available for these saws? Glue line versus rough rip? What else do I need to know about these?
Forum Responses
(Solid Wood Machining Forum)
From contributor A:
I have purchased new, used, and gang ripsaws for large shops. The ripsaw falls into two classes - glue line rip, and rip. Neither will remove the stress in a piece of stressed wood, but a glue line rip with a decent blade will prep thousands of lf of rough lumber per day for glue for width. A ripsaw will not necessarily produce a glue line rip, but it will prep straight enough for a molder or other operations. Most have a variable feed rate, and height adjustments for different thicknesses.
We used an old, refurbished Diehl SL52 for ripping rough Poplar and Oak 4/4 for gluing up 16' long 1 x 12. It is a wonderful machine. This same machine also ripped millions of lf for molder and S4S operations. A decent blade, proper oiling and maintenance, and the things will run forever, making money and ripping lumber. A good laser, properly set up helps also. Then make sure the operators do not wear gloves so they won't ride the board into that blade.
Talk to an old line machine dealer and listen to him. If buying used, try to have a tech from the factory look at the machine and tell you what it might need. Diehl still makes - or will make - parts for lots of their older machines. If the glue line is important to you, make sure the dealer will guarantee it for you. It won't replace your table saw, but you will see why larger shops refer to a table saw as a variety saw.
As to rip first or cross cut first - if you settle that one, you are a better man than the thousands that have already argued that question. There are good reasons for either method, influenced by what you make and the material you are using.
From contributor B:
I crosscut a lot of my stock first because the quality is poor, boards warped and narrow. I need to get two pieces 2-1/4" wide from a 5 3/8" board. It’s tough to do if it is long and crooked. If I have better stock I rip first. I use a triple chip (glue joint) blade for everything and never use a table saw unless the pieces are too short for the SLR. Many times there is so much stress in the material, I straight cut it twice before ripping for width.
From contributor C:
As a general rule if the material has many defects (knots, warp, decay) it is better to cross cut first. A SLR is a very strong and handy machine to do all the work you need. Considering the main two brands, I have used the Diehl's SL52 and the Mattison 404. I think the 404's are much easier to get a good glue line because these have the saw from above and the chain is only one wide piece. On the Diehl's the saw is set from below and there is a separation between the chains. The setting of these chains is very important and a little bit complicated. If not properly done, it could lead to joint problems (hollow on centers or open ends).
From contributor A:
Contributor C is correct about the setting of the Diehl's feed chains. But this also allows an adjustment of hollow to sprung joints. Any adjustment can be seen as adding to or simplifying an operation. In practice, the chains are adjusted only once every 18 months, when the chains are swapped from left to right to balance wear. I have no experience with the Mattison saws, or whether they can be adjusted.
From the original questioner:
Speaking of chains - would they tend to dent lighter woods, or is the tread less aggressive than something like a serrated planer feed roller?
From contributor D:
I've been contemplating buying a straightline rip saw for some time but I am concerned about the safety aspects. I owned a Diehl briefly but jettisoned it before it was brought on line. I had bought it at an auction for a great price and was in the process of refurbishing it when I learned that the newer Diehls had a double set of kick-back fingers, one from the top and one from the bottom. I have never run one of these machines but I heard that they can propel a large scrap like a spear. Any saw can do this but I'm more suspicious of a chain drive saw than others. When I learned of the new features I decided to wait until I could find one with the additional kickback fingers. During my research I was advised to situate the saw in a way that there was not a lot of traffic in the area behind it. Can anybody elaborate on this kickback issue? How often do these machines kick back scraps? Does it make a difference whether the blade comes from the top or from the bottom? How safe are these machines?
From contributor E:
After ripping 90,000 LF mine kicked back a narrow - I step to the side when ripping and now my helpers know why! It doesn't happen often, but it would only take one time to be the last time, if standing in the wrong place. Ripping rough lumber could be dangerous because of the varying thickness of the boards- a thin one may kick back especially if it has stress in it. I can't rip finish planed or sanded lumber on my Mattison 202 because it leaves dents and a small amount of oil from the chain on the surface, so a regular tablesaw is still used a lot.
From contributor F:
We've never had kickback on our Mattison 202. I don't know how many thousands of feet we've run through it, but it's been substantial. Nonetheless, everyone in our shop operating the saw knows to stand outside of the potential kickback path. None of us in the shop had ever operated a SLR when we fired ours up for the first time. The learning curve on using it was short, the ROI was incredibly fast (I bought it through an IRS auction for about 3 k, delivered), and it dramatically increased our throughput. The biggest challenge, given the machine is old, was finding appropriate lubricants for its various parts. I found it to be a critical partner to the S4S machine, and later the 5 head moulder we added.
From contributor G:
I’m getting a little uneasy reading these posts. We have a new SLR showing up this week and have heard about the kickback issue. I have been told to watch the kickback fingers and replace them when they break. And I am not proud to say, it is a made in Taiwan Oliver. I had intended to buy a good old Mattison or Diehl but the compact size of the import saws just fits our small space better. Question – how safe are the import saws with the kickback issue? I have been assured by our tool dealer that Oliver is good about taking machines back if not satisfactory. To contributor E: Good point about ripping rough lumber. We do that a lot with Mahogany and may have to rethink the process. Unfortunately the area behind the saw is a high traffic area in the shop.
From contributor A:
I don't have experience with the newer imports, kickback-wise. If there are EU standards to conform to, then they are likely better than the older machines. Top and bottom fingers are better than top only. Some older machines have fingers that can be jammed up out of the way – this is not good. The manuals always say to insure properly operating kick back fingers and to replace any broken or damaged parts. This time they mean it. While I have seen a t/l of rough lumber a week ripped on a SLR, I've only seen a few kick backs, none causing injury. It only takes one.
Once a day on average, a piece would get bound and threaten to kick, but the fingers would stop it, and the saw was shut down and the piece removed with no incident. The chains don't cause the kick - it's the saw blade. When the single blade SLR was replaced with a 50hp gang rip, things came back daily, but the operator knew where to stand, and he never had a close call. I have seen far worse on a table saw.
It is a good idea to keep the area clear behind the saw, and insure operators know to stand aside. Placement of the lumber stack to be ripped will help keep the operator out of the way - picking the next piece while one is fed thru the saw. I have painted yellow lines on the floor, and set up semi-portable wire screen walls to stop possible projectiles.
A Tailboy (ageist term) return conveyor is very helpful for small shops since an SLR is a two man saw for any quantity. The tailman does not want to jiggle or pull on the pinched ripping since he may inadvertently cause it to shoot back. The procedure should be to shut the machine fully off, remove the offending piece once the blade has stopped spinning, check the fingers, then start up. The productive gain will still easily offset this little bit of time.
The increase in productivity is the great gain, and the safety issue is very low, in my opinion. We always had more trouble with people wanting to wear gloves than with anything like a kickback. The learning curve is quick, and ROI is almost as fast. The safety issue is no stronger with this type of equipment than any other industrial equipment. Climb cut shaper setups still make me think three times.
From contributor H:
I have owned and used several straight line saws both top blade and bottom blade types. Our first machine was a top blade import that cut several million board feet of lumber. The problem I had is that it eventually wobbled out the groove in which the blade sits and would allow narrow edgings to slip under the blade and become projectiles. We would every so often remove the chain and epoxy the groove in and lower the blade into it solving the problem for a while. We had one instance of a Hickory edging 12' long lodging into the meat of an employee's leg. The ultimate demise of this machine was running it dry for an extended time destroying the chain. The flip side is this machine produced good glue quality edges and still did production straight lining.
For our next machine we went a bottom blade and split chain, which also produces good glueable cuts but I feel it is a much better design from a safety standpoint. The blade is always pulling down on your material as opposed to lifting up, and we have never had anything even resembling a kickback. It is larger and takes up significantly more space.
In summary, for a small shop with space limits and limited production I think a top blade import can be great addition. If you have the room and higher production requirements a larger bottom blade setup is best.
I will emphasize - these machines can and eventually will kick back material so be prepared. Do not stand directly behind and have a clear safety zone behind it. We use a moveable plywood barrier that sits directly in the line of fire and is adjusted to the length of the unit.
From contributor G:
Thanks everyone for all the good advice! We will have some rules and a portable safety fence.
From contributor D:
I have another question about SLR saws. I can see how they would be good for producing one straight edge. How are they for ripping sticks out of boards? Say I have a ten inch board and I want to get three sticks +/- 3 inches wide. Do I rip one straight edge then feed it into the fence like a regular tablesaw?
What is more productive - straightening one edge then powerfeeding staves on a second saw, or doing all rip cuts on the SLR?
From contributor F:
The SLR is great for ripping sticks. Typically, we preset the fence to the desired width, rip one straight edge, using the laser to identify the best location on the board, and send the board back to the operator, who then rips it while it rides against the fence for an accurate blank with two parallel edges. Usually these blanks go right to the moulder where they are further dimensioned. We have just started experimenting with setting the fence to 3/16" and ripping strips destined for bent laminations without any additional processing until after the glue dries. It's working, but I'm not yet confident it's the best route to take for this process.
From contributor D:
That is encouraging news. Right now we are straightening lumber on a Martin Jointer then ripping with a Hitachi bandsaw (3 inch blade). This works okay but it's kind of slow. The guy to talk to about thin rips is probably BH Davis. He generates miles of this stuff for his curved molding business.
From contributor G:
Got the Oliver powered up this morning and had time to run just a few boards. I see a couple small issues with the machine, but overall I think its going to work. The compact size works well in our 4000 foot shop. We have to run 4500 feet of White oak T&G next week and that should be a good test.
I have a couple of questions - I adjusted the rip fence parallel to the saw groove in the chain as per the manual and noticed the fence has a .5mm belly to it. (Made in Taiwan) The few rips we did came out within .2mm end to end on a 14’ board. This seems very good considering most everything ripped will go through the S4S and is oversized anyway. Does the fence straightness need to be corrected? Maybe it’s not an issue because the fence is quite a bit in front of the blade.
The laser shoots a line about 7 or 8 feet and that seems a bit short. I adjusted it out when doing the 14 foot board, but then it was short at the in feed which made it hard to gauge short boards. I think the guys at Oliver said a better one was available. Would there be any advantage to setting the rip fence at 3/8 to 1/2” to help guide for the straightening rip? Of course then it would have to be reset for every rip. Probably just need some practice. I do like the ease of going to different thickness. That is the issue with a power feed table saw. The change of thickness is difficult by the time feeder and blade are adjusted. And not getting sawdust in the face is nice.
From contributor B:
If that was my rip saw I would make them send a new fence. I use mine to cut to size so I would want it straight. My guess is that in time you will also. The distance in front just means short pieces don't work too well. I don't have a laser so I do use the rip fence to gauge straight, however a 14' board would be tough for me. The difference between this saw and a power fed table saw is like night and day.
From contributor A:
I think of a SLR as a rough mill machine - approximate width as prep for molder or other final sizing operations. An eighth inch is acceptable. In practice, we used the saw to rip rough boards, with first a shadow line and later a laser. The rough board edge would be aligned under the light line, just touching the edge, and fed into the saw. The board would be returned and moved over to the fence for a rip to width, or flipped over and edged again for glue to width. A dedicated cart on the tailman's left caught the rippings, and the stock would go to cart just below the saw exit.
The shadow line and later laser both benefited from segregating the lighting in the immediate area so the saw operator could turn off the lights above the light lines. This helped make the lines stand out. We set up the gang rip with up to 4 adjustable lasers that could project the rip pockets on any given board, but the darkened area really made it quick and easy.
I’d award five bonus points to any of you for finding a good use for the rippings. We always had people who wanted all we made to make kindling for sale. After 3-4 bundles, they would burn out and want no more. There is no easy way to handle all those sticks.
From contributor E:
I have a rack for the rippings that has vertical slots every two feet. When it's full I crosscut them all with a chainsaw and stack it in the firewood rack by the wood stove. I keep thinking I'm going to bundle it and sell the bundles for kindling but don’t have time to.
From contributor G:
I wanted to report back about the SLR after using it for a while. Thanks everyone for taking the time to post about their SLR experience. It was very helpful and accurate! As for the Oliver, it’s going to work good in our system. At only 30” wide it fits our tight space. It is the smaller Oliver and does not have all the features or power of the big brother. It handled the 5500 foot run and is also convenient to rip just a couple boards. The height adjustment is easy. We will keep a Unisaw on wheels around just for the odd stuff. Large solid wood panels can be ripped on the slider. The Oliver will rip to about 14” plus. The chain does not leave marks on the board but I did notice a little oil in spots. Probably do not want to rip any sanded material. We normally don’t anyway. All the boards except for a few badly warped ones came out straight and parallel. This saw has no adjustment for doing a hollow glue joint other than setting the fence out of alignment. That would not be practical. This is probably where the old Diehl’s and Mattison saws shine. I looked over the Diehl website and looks like an old machine bought for the right price is a safe bet with the replacement parts available.
One thing the imports might have in their favor is up to date anti-kickback systems. The Oliver has 3 sets with the first ones on the bottom. I never felt we were in danger of kickback but will take the precautions. The learning curve for the straight-line cut was fast. The first couple were intimidating. Our laser worked for the 10’ length but anything longer would be hard. The Oliver Company said they would send a more powerful laser and take the old one back. The machine is smooth running and over all the quality is better than I expected for the price.
It is night and day difference from the power feed table saw. Edging then ripping for width without much walking is fast. Any shop working solid wood could benefit from a SLR. And I can see the advantage of a moving blade gang rip for production work.
If the picture posts you can see the kickback fingers in the table, our 2nd try for the return table (The Doucet return conveyer looks good or at the least a slope table with a conveyer) and the use of our Hafele panel cart for the rippings. I can pick it with the fork lift and deliver it to a neighbor who takes all our scraps for firewood.
