Laguna LT18 (2002) tension max?

[James Baker SD]

I have a Laguna LT18 (ACM circa 2002). It is been out of commission for about 6 months since I destroyed a couple of the ceramic guides. While the guides were off, I toyed with trying to increase its resaw capacity beyond the ~12" it has by making a new mount for the guides, so I took apart the blade guard and guide support. I ended up putting it back together as it came figuring I will worry about the resaw height when I actually need it. Last point of background, some time ago (several years) I had an over-lubricated blade slip off the wheels while the saw was running with a very loud pop. After getting the damaged blade out, it seemed that the tensioning wheel would not catch. Without taking the top cast iron wheel off, I played around and eventually got it to seemingly work.

Today I tried to resaw a piece of scrap maple only about 2" thick. The cuts are terrible. (if looked at on edge, it is a classic sawtooth waveform from an oscilloscope) I was using a 1"x 0.025" 1.3 tpi steel blade, fairly new. Of course I wonder what I was doing wrong (I have gotten better resaw results in the past), but my question for today is:

How much tension should I be able to put on this blade? (I believe it is a Laguna pro force blade). The LT18 has a "tension" scale that reads from 5 to 30 for the mm width of the blade. I put a decent tension gauge on the blade and cranked up the blade until the Laguna scale maxed out at 30. The real gauge was reading only 15000 psi. This seems kind of low to me, especially given all the comments I see about very high tension required for resaw here on the forum.

What should an LT-18 be capable of?

Is there a chance the Laguna scale got miscalibrated when the blade slipped off several years ago?

Could my spring be damaged from that incident years ago?

I would like to do a reasonable amount of resawing (I know this is not the ideal saw, but it is what I have) and the simple test results today were pretty discouraging. I am fairly mechanical and reasonable confident I put the blade guard, and guides back on correctly. So, do I just have an ill saw that with TLC can be restored to health or am I asking too much of it? Thanks,

James

[David Kumm]

Take a look at the spring first and see if it is bottomed out. I think 15000 may be about as high as it can go with the stock spring. At least that was all my late 90s LT18 would tension. I upgraded the spring from Iturra and it helped some but the whole tensioning assembly isn't real strong so there is only so far you can go. Your problem might be a bad blade though. 15000 should work with a steel blade. I'd try another. A good 1/4" blade should cut 2" maple although it needs more tension to do it. Dave

[Steve Rost]

Your on the path I would choose. Put everything back and go thru the complete new saw set up procedure. If your results are the same then you will need to go deeper into the saw, alignment of wheels, tires ect. I have an LT16" and tension may be your issue if it is not correct. Call the factory and you can get the correct tension psi and not depend on that dumb scale on the saw.

[Erik Loza]

James, I believe your ACM is the same as our MM16, et al, in this way. You should be able to calibrate that on-machine tension scale to your taste. The black plastic box that has the scale on it should unbolt from the chassis. If you turn it around in your hand, you should be able to see where the pointer is screwed tight to the cable. The procedure I recommend to my customers is to track and properly tension the blade you most commony use on your saw, then adjust the pointer to that corresponding reading on the plastic scale. Of course, it will be impossible to have the on-machine gauge be accurate for every blade you will use (due to different metallurgies, thicknesses, etc., which is why I suggest doing this with the blade you will use most often...) but this is an adequate quick-reference point that will work.

I personally doubt there is anything mechanically wrong with your saw, by the way. Sure, upgrading the spring is never a bad idea but pretty unlikely anything is actually "wrong" with the machine and I agree with Dave to make sure nothing is bottomed out but Italian saws are pretty bomb-proof. I have never heard of a damaged tension spring in all my years. At least not on one of our machines. Your poor cut quality just sounds to me like inadequate blade tension or (possible, though less likely...) a bad blade. "Fear of over-tensioning" is probably the most common issues I see, especialy on wide blades like that one you were using. Ditto what Dave says: Try some smaller blades and see what happens.

Hope this helps,

Erik Loza
Minimax USA

[Andrew Joiner]

Isn't it funny when you get great customer service on a Laguna? It's even funnier when that service comes from Minimax! Good for you Eric.

I need to say that I did have a problem with a new resawking blade 4 years ago and Laguna did give me excellent customer service.

[David Kumm]

In addition to what Erik says, keep in mind that when you finally start to build tension the wheel begins to move real hard- takes both hands to turn it. If the spring has not bottomed you turn a good full revolution after it gets difficult. Don't worry if the scale goes off the edge. you won't hurt anything on the saw with the original spring so go until it almost closes up and backoff just a touch to be sure. Dave

[James Baker SD]

Thanks to all.

One of my original questions was if the scale had become miscalibrated during the blade slip and subsequent problem. I stopped turning when the scale maxed out for fear of damaging something. I assume the lead screw still had threads left so I could have turned it more (probably) but was afraid to try. I don't think I can see the spring without removing the top wheel. Is there another way to determine if it has "bottomed out"? Perhaps pushing on the top wheel with no blade at all to feel the spring?

I will try some smaller blades today and check the scale. What should be my target psi on a 1/2" steel blade as measured by a Starrett Bandsaw tension gauge? That's my typical blade as the saw is used mainly for cutting swallow curves rather than resaw.

James

[David Kumm]

James, I'll have to look but remembered there was a way to see the spring through a hole in the wheel. If you can still turn the wheel the spring is OK. It doesn't move at all when bottomed out. Again, don't worry about the scale. Add 1/2 turn and see if that helps, if not try another if the wheel will turn. Always run past and back off a touch. I run 25000-30000 on my small Starrett bimetal blades and 25000+ on the Lenox trimasters. You won't ever want a Trimaster on that saw although a 3/4 Resaw king should work. Some steel blades are designed for low tension so 15000 should give you a decent cut. Be sure to preload the tension gauge. Then you should be able to make several turns before it begins to climb. Then only one to two turns will bring up the gauge. Don't be afraid to experiment with different tension, just be sure the blade tracks before starting it up and letting it get to full speed. A change in tension can affect the tracking. Dave

[Mike Heidrick]

I was told buy Sam at Minimax to disregard my gauge numbers when tensioning Lenox Woodmaster and Trimaster (and Laguna Resawking I disregard it as well). I have no scientific way of tesioning them other than "flutter" and sound test. I test my cut and tension some more. That trimaster tensions off the MM20 numbers/chart. Never had an issue cutting though.

I have also never lubricated the blade to a point that affects wheel position. How does that happen.

MM wheels are flat so maybe that makes a difference?

Learning from all your experiences everyone so thankyou for any info.

[James Baker SD]

I have also never lubricated the blade to a point that affects wheel position. How does that happen.

MM wheels are flat so maybe that makes a difference?

Learning from all your experiences everyone so thankyou for any info.

At the time I was running the blades toward the front edge of the wheel tire to keep the teeth clear of the rubber (not sure where I read that, but it wasn't my idea). I had also heard that PAM (non-stick cooking spray) made a good saw blade lubricant, so I was spraying the blade as the saw was running. Not making a cut, just spraying. The Laguna's tires are crowned and I guess the excess lubricant got on the rubber tire and the blade just slid off the crowned edge.

The blade was destroyed with a couple of near 180 degree bends in it. After stopping the saw, I got the blade out, wiped down the tires with alcohol to remove the PAM, and went to put on another blade. This is where my memory is fuzzy, it was several years ago, but I seem to remember the tension wheel spinning freely not doing anything almost as if the lead screw had come out of the threads it turns in. I simply don't remember what I did to re-engage the threads (if they were ever really disengaged?), but the saw seemed to be OK and I've used it for several years (not heavy use though) without giving the tensioning another thought.

I no longer lubricate blades and I now run them in the center of the tire as the crown keeps the teeth off the rubber anyway and they seem to track better in the center.

James

[David Kumm]

James, crowned tires must be a change from my earlier model. What is your resaw height and motor? I use a wax stick on the blade but have found the best is to not rely on the back bearing except for the most strenuous of cuts. Blades last longer if not heated by the bearing. Crowned tires are not common on Euro saws but if crowned they generally will track to the center. Dave

[James Baker SD]

James, crowned tires must be a change from my earlier model. What is your resaw height and motor? I use a wax stick on the blade but have found the best is to not rely on the back bearing except for the most strenuous of cuts. Blades last longer if not heated by the bearing. Crowned tires are not common on Euro saws but if crowned they generally will track to the center. Dave

Dave, I just went out to the shop to confirm that the saw does have crowned tires. Not much of a curve, but definitely not flat. The saw was manufactured in 2002, has a resaw height of just under 12" (300mm on the spec sheet) and originally came with an Italian 3hp, single phase motor. I have since upgraded the motor with the 4.5hp Baldor single phase motor Laguna offered a few years back. I also replaced the OEM guides with Laguna ceramic guides several years ago. I recently had to replace the ceramic inserts in the guide bodies as two of them had cracked.

Slightly off the original question, but I thought good resaw required high beam strength of the blade. I also thought beam strength was a function of tension and a function of width of the blade. Therefore it seems a 1" resaw blade would have more beam strength than a 3/4" blade would. Now if the 3/4" blade can be tensioned higher on a given saw, then that is a plus for it. Where do the curves cross? How do you decide (short of buying 1 of each and trying them out) which is the way to maximize beam strength on any particular saw?

James

[David Kumm]

James, sounds just like my LT18. My tires are flat except for maybe some wear but not like crowned tires where you can see the division between the flat and the crowned portion. In my world tension beats blade width. I've never bought a blade wider than a 1" Trimaster. Granted the .035" thickness goes up to 1.25" I believe and then gets thicker but need to verify. At 25000+ I've never had a blade wander but I haven't resawed 20" hardwood enough to be sure. The Resaw King runs a .024" band so you can go wider with it. It really comes down to the saw's ability to tension that determines what blade to use. I could not tension a 3/4" Trimaster over 15000 so I went to a 1/2" .025 blade. If i were buying a carbide blade for your saw it would be the 3/4" RK. My Yates Y20 is an old cast iron saw and I use a 1/4" bimetal blade tensioned to 30000 and can resaw 8" with no issues. I use it to cut tenons as it is so exact I can cut them a few thousands thinner at the end than at the shoulder with no inconsistency so beam strength isn't my first priority. Dave

[James Baker SD]

Well I've spent much of the afternoon playing with the saw. Removed the 1" blade and I can raise the top wheel until it hits the roof of the saw. For the life of me I cannot see a spring in there anywhere. Not easy to see without disassembling the upper wheel which I do not want to do, especially since others have said the saw would not work without a good spring. I will trust you that the spring is in there somewhere.

I put a 1/2" steel blade on and easily tensioned that to 30,000 psi without even maxing out the tension scale. Then switched to a 3/4" steel (may be a resaw blade I bought because it has variable pitch teeth spacing). I got it up to 27,000 psi with the Laguna scale maxed out. There was plenty of threads left on the acme screw on the tensioner, so it was only the scale that was absolutely maxed out. I dropped the tension to 25000 psi and I then adjusted the ceramic guides for the new blade, cleaned off a bit of rust here and there and put a super light coat of beeswax on the blade. Started it up and continued the resaw test from yesterday (2" scrap maple) and got really decent results: consistent thickness and ready for a smoothing plane or ROS. I took Eric's suggestion and re-calibrated my tension scale to match the 3/4" blade.

While the saw was apart I modified to dust collection ports. The saw has a 120mm port on lower right which was reduced to 4" for the American market. I swapped it for a 5" adapter that completely covers the 120mm opening. Also modified the lower blade guard to add a 2nd, 4" port right below the table. My first test of anything connected to the permanent ducting I am installing for the Oneida cyclone. Really pleased with how little dust escaped. Just a little on top of the table, none inside the cabinet, and my Dylos stayed in the very good range.

Time to stop for lunch, but will do a couple of more tension tests on different 1" blades later today.

James