Thread: Cannot remove drift on blade

Originally Posted by John Samuel

I am still fine tuning the Laguna and have bumped into a problem I don't know how to solve.

When I try to cut veneers, they are coming off as a wedge shape ... the saw wants to pull the work piece off the fence. I was sure this would be a drift problem, but now I'm not so sure.

Sorry. Sometimes I can't post pics. Sometimes I can post thumbnails. I'll try. The computer tech will be here Monday to fix the darned thing.

I set the fence to account for drift. If I re-saw a board or cut a veneer, the blade pulls the board off the fence and the blade cuts towards the side of the work piece against the fence. I can see that the back of the blade is not centred in the cut. The left side (from the front) is open at the back and on the right side the back of the blade eventually touches the wood. The taller the board, the bigger the problem.

On the other hand, if I cut a board, say 30 mm thick and stop the saw halfway through the cut, the back of the blade is not touching wood on either side. That's why I thought the saw was set OK for drift. However, a closer look reveals that the gaps between the blade and the wood, whilst parallel, are different. The gap is wider on the left (fence) side than it is on the right side.

I have checked the guides and they seem fine ... as per the manual. The only clue I can see is the difference in the gaps either side of the blade and the only cause I can imagine is that the teeth are not set right (that is that more tooth is exposed on one side of the blade than the other ...CT blades don't have "set") ... on a brand new blade.

Can anyone help?

Thanks,

John

Hi John,
By wedge shape I take it you mean that they start out at the set width, say 1.5mm, then as the cut proceeds the thickness increases to say 2.5mm at the completion of cut but remain even in thickness from top to btm.
Based on the position of the blade you describe the blade is turning into the workpiece that is up against the fence and pulling the wood off the fence and if you maintain pressure on the wood to keep in against the fence the blade still turns into the wood and the offcut thickness increases.
A few things to try....
you could..... (not in any order) try the simple things first and see what happens
.....reset the fence for this new drift,
.....set the blade further back on the wheels, if I understand correctly this tensions the front of the body of the blade and potenially imparts stiffness,
.....wind a bit more tension on the blade,
.....examine the blade teeth closely, my reckoning would be that the right side teeth are blunter than the left, think you said it's carbide tipped, they can still suffer one side blunter than the other, if this is so the right side will have a very small shiny rounded edge on the corner of the tip which won't be easy to see especially if it's triple ground, there might be a straight ground tooth every third tooth that might be easier to see, I reckon there would be an optical magnifier out there somewhere that's perfect for doing this, sometimes it is possible to guage the difference between right and left by dragging a finger tip over the point, sharp will catch, blunt will slide, bit unscientific is more a "feel" kinda thing,
.....if the right side is blunter than the left maybe dull the left side to match the right,

If it were me it's due for a sharpen, my local sharpening bloke won't sharpen my TC blades, has doubts about his machine so I do them myself, maybe someone will do them in Bris

Pete.

Thanks, Pete.

At the same time I posted the issue I sent a message to the supplier. He reckoned I should increase the tension and check the guides.

I re-set the guides ... very, very carefully. I increased the tension, that helped, but only a little.

I am pretty sure the problem is the blade. I have the fence adjusted to the maximum drift it will allow (10 mm over 400 mm), but when re-sawing, it is not enough.

There is no correct drift for this blade. When not cutting, it sits dead square in the throat slot. When running there is almost no vibration and when running but not cutting the blade appears as a dead straight, very still black line. If I cut thinner stock (say, 25-30 mm), the back of the blade touches the wood on the left (fence) side and the blade wants to drift right. Once the material is 60 mm or thicker, the back of the blade touches the wood on the right side of the cut, and the blade wants to drift left, despite the fence being on maximum adjustment.

I have sent a note to the supplier, complete with photos and a brief statistical examination of the data. I thicknessed a 100 mm board and measured it every 50 mm. Then I cut off a veneer and remeasured the stock and the veneer. The degree of variation in the data doubled when comparing the thicknessed piece to the cut piece. This is to be expected, but the cut piece is still very smooth for a saw cut. The blade drifted in towards the fence at the top, it drifted out at the bottom.

The saw is fine. I am sure the problem is the blade. Have told the supplier that. Now I wait until Monday for a response.

John

I would also experiment with the feed rate. If the feed is too fast the blade is more likely to distort (twist). Try an exceedingly low feed rate and see what happens.

Originally Posted by mat

John

I would also experiment with the feed rate. If the feed is too fast the blade is more likely to distort (twist). Try an exceedingly low feed rate and see what happens.

Thanks, Mat.

I spent the day yesterday experimenting. Very low feed rates help a little, but do not solve the problem.

Roll on Monday!

Cheerio,

John

Originally Posted by John Samuel

The saw is fine. I am sure the problem is the blade. Have told the supplier that. Now I wait until Monday for a response.

John, can you please tell me the position of the blade on the lower and upper wheels? I presume it is a 3/4" Laguna Resaw King blade

Originally Posted by Dengue

John, can you please tell me the position of the blade on the lower and upper wheels? I presume it is a 3/4" Laguna Resaw King blade

It is a one inch Laguna re-saw king blade, supplied with the machine.

The blade is centred on the top wheel ... it almost fills the tyre width. It is a tad further forward on the lower wheel ... maybe 2-3 mm.

I think one clue here is that there is no correct drift for this blade. In thin material it tracks straight and true with almost no drift adjustment.

I have applied maximum drift adjustment in an attempt to cut wider boards (fence is angled 10 mm over 400 mm).

Now the blade drifts right in thin material and drifts left in thick material.

The other clue is that when it was tracking well in thin material, the gaps between the blade and the edges of the cut are different on each side of the blade.

Cheerio!

John

Thanks John, looks like you have pretty good alignment of the upper and lower wheels, so that is not a problem. Be interested in what GM have to say next week.

I haven't had any luck with my Laguna 14/12 and all its inherent problems - their customer service just don't reply to my emails

Originally Posted by John Samuel

I re-set the guides ... very, very carefully. I increased the tension, that helped, but only a little.

John, Like you I am no expert but the fact that increasing the tension made an improvement indicates that it needs more tension. A one inch blade must be at the extreme limit of the machine, have you got any other blades to use? I would put maximum tension on it to see what happens.

From my experience (somewhat limited), very few BS can properly tension a 3/4" blade, let alone a 1". Yes, the Resaw King is a thin kerf blade but still requires a minimum amount of tension in order to resist deflection (if indeed this is the cause of your problem).

My 18" BS can only "just" tension a 1/2"Lenox bimetal blade to 10,000 psi, likewise my new 24" Felder can tension a 1" carbide blade but to achieve the recommend minimum 20,000 psi, requires the indicator to be way off the scale. This is as measured with a Starrett tension gauge. I think that to tension the 1" carbide blade to 30,000 psi may permanently deform the tension spring in my Felder.

I seriously doubt if you are able to achieve the necessary tension required for beam strength a 3/4 or 1" blade on a 14" machine mate. It my be wiser to try a 1/2' blade and apply greater tension.

Yes Michael Fortune recommends lower tension, but we are mere mortals compared to him

Agreed, non of us here are experts, but we are all more than willing to give advice; some of it is going to be useful, and some will likely lead to confusion.

Originally Posted by drmark67

From my experience (somewhat limited), very few BS can properly tension a 3/4" blade, let alone a 1". Yes, the Resaw King is a thin kerf blade but still requires a minimum amount of tension in order to resist deflection (if indeed this is the cause of your problem).

My 18" BS can only "just" tension a 1/2"Lenox bimetal blade to 10,000 psi, likewise my new 24" Felder can tension a 1" carbide blade but to achieve the recommend minimum 20,000 psi, requires the indicator to be way off the scale. This is as measured with a Starrett tension gauge. I think that to tension the 1" carbide blade to 30,000 psi may permanently deform the tension spring in my Felder.

I seriously doubt if you are able to achieve the necessary tension required for beam strength a 3/4 or 1" blade on a 14" machine mate. It my be wiser to try a 1/2' blade and apply greater tension.

Yes Michael Fortune recommends lower tension, but we are mere mortals compared to him

Agreed, non of us here are experts, but we are all more than willing to give advice; some of it is going to be useful, and some will likely lead to confusion.

You raise a good point, Mark. My cheap Hafco 12" couldn't even properly tension a 1/2" blade and gave me enormous trouble with drift and rough cuts. When I swapped to a 1/4" blade, all of the problems disappeared and it cuts beautifully. I even do all of my small resawing, (<=125mm), with the 1/4" blade now.
Not that I'm saying the answer in this case is to go right down to a blade that narrow, but narrower could make a big difference.

I tend to agree that a one inch blade is more than the machine can handle. I would say from reading others experiences that every modern fabricated saw has a big issue tensioning wide blades. Jet had to re-design their 18" saw due to flex in the spine when blades were tensioned. I used a one inch blade on a late model 18" Jet but it was not for serious work and it would deflect wherever it felt like it. I never fully tensioned it though as I did not need accuracy cutting firewood.

Have to agree with the last few posts - although the saw can accommodate a 1" blade, and has many features designed for resawing (large motor, etc.), there's no getting around the fact that its still a 14" saw.

I would have said a 3/4" blade was the maximum that this saw can adequately tension, TC tipped or not.

A 3/4" Resaw King would surely be more than adequate for cutting veneers?

I would also be adjusting the position of the blade on the wheels slightly - the drift figures you quote seem rather large. If the saw is cutting a wedge (i.e. blade drift towards the fence) then the blade needs to go further back on the wheels.

Originally Posted by Chris Parks

John, Like you I am no expert but the fact that increasing the tension made an improvement indicates that it needs more tension. A one inch blade must be at the extreme limit of the machine, have you got any other blades to use? I would put maximum tension on it to see what happens.

The good news is that I am sure my problem is the blade and not the machine.

I have tried max tension. Helped a little but not much. It is easy to get huge tension with the Laguna.

I am now sure that either the teeth are not set correctly in the blade, or that some of the teeth are damaged on the right side.

I will buy another blade, probably a 3/4" Woodfast or similar to use while I am negotiating with the supplier ... need a spare blade anyway, and always intended to get one.

Cheerio!

John

There is a good BS blade supplier in Brissy I believe. Pat who inhabits the wood turning forum knows where they are as he has recommended them in the past.