Gang Ripsaws, Movable Blades, and Optimizing Production

      A question about buying a straight-line ripsaw with movable blades turns into a wide-ranging discussion about optimizing stock production on various kinds of ripsaws. January 17, 2011

I'm looking for a programmable arbor gang rip. I know Mereen Johnson and Raimman both make these machines. What other companies offer these, and who has the best value? I'm looking for something in the 100 hp range.

Forum Responses
(Solid Wood Machining Forum)
From contributor A:
Stiles Machinery Kentwood line is interesting. I have been looking at their midsized offerings, you would need to look at their larger Elite series (Italian made) to get the largest hp and feed speeds.

From contributor UD:
I sold many movable saw machines. I am totally out of it now, but I have a couple of suggestions that you should take seriously. First is to decide whether you want to make glue joints. Everyone promises it but only a few can make joints without a high percentage of joint failure.

Second, you need to seriously analyze your desired rip widths. You also need to determine whether you want exact rip numbers or whether you are going to inventory widths for sale or use. By that I mean that if you want 500 rips of one width and 5 of another and no more, a movable saw is a necessity.

If you are ripping wholesale building material, for example, and to get the 500 rip widths you also get 150 of that which five would be sufficient, it matters not because that is a commodity product and you just put it in the bin for the next time you need any. If you are ripping products that do not have to be in exact quantities and can stand some over runs, a wide machine such as a 36" arbor will give you excellent yield and is much easier to maintain than a movable saw machine.

I don't care who tells you different, a movable saw machine is not the machine for anyone who does not have highly skilled operators and maintenance people. Not only does the machine require daily, and I do mean daily not "let it go until Saturday" maintenance, but they are expensive to maintain in terms of replacement parts.

A standard arbor machine is much easier to live with. A wide machine will give you a wide selection of pockets. That and a good software program will do a lot to control the quantities of each rip width. MJ makes a 36" machine as does Progressive. Both will make joints superior to what you will get from a Mattison or Diehl rip saw. I think they will both manufacture a 48" machine.

From the original questioner:
I already own a fixed arbor gang rip. Flexibility and efficiency is most important for my operation. We manufacture some commodity hardwood profiles in mass quantities, yet we also produce specialty flooring in various widths. Ideally I would like at least a 24" arbor with three movable blades and fixed width capacity. We sometimes saw 60- 80,000 lineal feet per day. I need a saw that can handle this capacity and also give me flexibility for specialty orders. Glue joint is of no importance. I'm ripping moulder blanks only.

From contributor U:
Are you using a rip optimization mechanism now? If so, whose?

From the original questioner:
I'm not using any type of rip optimization now. We do produce large quantities of a 1/2" wide produce which is generally included in my arbor setup. This helps my yield drastically but we're constantly changing rip patterns on the arbor due to various width flooring blanks needed.

From contributor U:
I would have a hard time finding all of my old stuff. Most of it is in Windows and I have been using Linux for several years now, but I will try later. The point is that I could show you if I had it that you will improve rip yield by as much as 10% simply by putting a rip width optimizer with a moving fence.

A fixed fence makes a lot of wasteful edgings. Further, you can get certain widths when they are available and will give decent yield. You can do this with systems less complex than the systems we built at NOVA. The NOVA systems were designed to and did rip for width yield and at the same time scanned for defects that would be cut out at the cut-off saws. So they calculated rip and cutoff yield.

For instance, suppose you want a 4" for plank flooring. If the 4" is there and it can get it with a decent rip yield, the fence will align the board with the arbor in such a way that you will get the 4" along with something else useful. If the board will not get the 4" with a decent yield, the fence will send it to another place on the arbor where the saw pockets are spaced to get the best yield out of it. I have been away from it for almost ten years now so I have not been following the new products by MJ and Weinig but both of them can do a decent job with rip yield.

From contributor T:
If you need movable blade technology get the Raimann. I run a KR610 and every day ask myself why and the world didn't we get one sooner. With what you've said so far you'd probably be looking at a KR450 3/M with a Valurip 4 infeed. Not sure why you wanted fixed width capabilities; it only takes about ten seconds to change a cut list. The part about needing a lot of maintenance is not any different than any other piece of equipment. Raimann is pricey but it's the best.

From the original questioner:
The only reason I would like some fixed width capacity is because we saw large volumes of 1/2" strips from boards (not edgings). With that being said, we'll sometimes setup to rip truckloads of lumber into 1/2" strips. It would be nice to have part of my arbor setup full time for this scenario and use other parts of the arbor for movable blades in a two or three flooring rip dimensions for random width material. For the saw we run now, we build an arbor with 20 blades but its very time consuming switching from that to a 4 1/2" cut. I've seen the Raimman saws and they are very impressive. Do they offer a saw with more than one movable blade? If so, do they have a software package comparable to the Mereen Johnson 312 DC/SR select a rip?

From contributor U:
What make saw are you using now? In addition to the make of your machine, the arbor width would help. However, just to get your attention, try this. It is a very simple way to illustrate how much your yield will improve with even the most rudimentary rip optimizer.

Take a sheet of graph paper or with a ruler lay off points on a sheet of paper. It does not have to be to scale to prove the point, but if you draw it to scale you can see what it will do to get your 4-1/2 rips. Draw little lines over the points you laid off so that each line represents a saw. Ignore kerf allowance. Now take several strips of cardboard that are random widths which will represent random width lumber. Place a strip over the "blades" and shift it right or left until you find a place where there is a blade exactly on each edge of the "board". It is easy.

Now tale the same strips and put them up against your imaginary fixed fence. You will end up with an over sized edging on the side opposite the fence. There are expensive ways of doing this which will do it automatically and with great precision or older slower methods such as using a laser for each saw blade and asking the operator to manually move the board until he gets the saw pattern most desired.

A 24" arbor makes it much easier because you can have more pockets. If you put the 4-1/2 pocket in the center and vary the widths on each side, the yield will be better. In other words, don't set it up with all 1/2" strips on each side. After playing with it a few times, you can get pretty good even when given some new sizes.

My point is that for rip optimization only, that is no consideration of defects, there is a lot you can do with your present saw providing it is 19 to 24" wide - 24" preferred.

From the original questioner:
The saw we use now only has a 12" arbor. Are you saying I should just look at a 24" fixed arbor gang rip rather than the movable blade?

From contributor U:
The answer is 90% yes until I have time to explain a little bit more and you can then make up your mind.

You need an all moving saw machine, or one with several moving saws, if you require exact numbers. For instance, a furniture plant that in a cutting requires 500 of this 250 of that and 1,000 of those.

If you get only 240 when you need 250, you will not have enough parts to complete the number of cases in the cutting and if you get 275, you end up with over stock stacked all over the machine room from the many other cuttings that resulted in overstock. So you need the exact number of pieces. We accomplished that by scanning for length defects as well as rip defects ahead of the rip saw. The scanner ahead of the saw did not do anything except optimize the rips based on what it predicted would be cut off defects. A scanner ahead of the optimizers told the optimizers how to defect. The advantage of looking for defects ahead of the rip saw was that it kept the rip saw from flooding the optimizers with material that was not what they needed.

As the optimizers started getting numbers close to the desired numbers, the central computer would tell the rip saw to cut some other width until the material on the chain was cut to length. If it was determined that the optimizers needed one more length or 5 more to get the required parts, the central computer will tell the rip saw to move a saw into place for that width and rip the requested number. I go through all of that to explain why this concept came about.

The other reason for an all moving saw machine would be someone that is going to rip maybe only 100 of this and 5 of that and 25 of something else. Fine, but it had better be a really high priced product or he will never pay for the machine and its maintenance. I have told many that everyone thinks they need an all moving saw machine but only a few do.

You mention random width flooring. I think that I would call your product multiple width flooring because my definition of random and that used in the furniture industry is any width with no restrictions on size other than not to exceed x and not to be less than y. So instead of 4-1/2 and 4, 3-1/2 and 3, we would rip 3.125, 3.127, 3.whatever. Because random all went to glued up panels so we ripped it to get yield and not any dimension so long as it was within a maximum and minimum range. Most furniture people call this glue up and don't even use the term random even though that is what it is. So if you have certain sizes of plank flooring, say 4-1/2, 4, 3-1/2,3, 2-1/2, etc., what you would do is build an arbor with one or more of these widths mixed with the smaller widths. Because you get repeats for those same widths, it matters not if you cut a few over. Just hold them for the next order.

You mention long set-ups. You should be using saw sleeves so that all set up time is spent in the saw room and none on the machine. With a MJ, you can change a sleeve and be running in 5 to 7 minutes. While the machine is running with sleeve #1, someone in the saw room is setting up the next sleeve. Try the drawing and the cardboard strips I spoke of earlier and you can see how this would work on a 24 machine.

As I said, I have been out of it for some time now and am not informed on the present state of scanners. I know that MJ, Raimann, Taylor, Styles and many others were developing various forms of scanners and as I pointed out earlier you can use lasers to line up with the saw blades for a homemade set up. Obviously the commercial scanners are much better if you can spend the money.

An addition to the above regarding set up. If you set up your own designed laser lights, there will be so many of them that set up will not be quick because you will also need to move each laser. If there is one for each saw, that is going to take a lot of time. The manufactured units determine the width of the board and do the math so as to get the most out of it, so to set that part of the system up is quick enough. The operator enters the saw spacing in the system and it does the rest.

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