Thread: Problem with 3/4" Woodmaster B 1.3TPI......what am I doing wrong?

I wonder if the 3/4" wide blades are just too narrow for 1.3TPI so don't have bought metal behind the gullets to hold the blade true?
My 1.3TPI blade is 32mm wide and the 1TPI and 0.66TPI blades we run on the bandsaw mill are 50mm wide.

I have no idea to be honest Bob, it definitely didn't appreciate my attempt to rip a 4" hardwood post lol. Jammed twice before I gave up in fear of what might happen next......I would say that the blade does seem to have a fairly wide kerf, which for some reason surprised me....

Originally Posted by nigelr

I have no idea to be honest Bob, it definitely didn't appreciate my attempt to rip a 4" hardwood post lol. Jammed twice before I gave up in fear of what might happen next......I would say that the blade does seem to have a fairly wide kerf, which for some reason surprised me....

The kerf should be no more than ~1.5x the thickness of the blade, whoever set the teeth might have been over zealous about it. If required you can reduce the set a whisker by rubbing the sides of the band/teeth with a shaprneing stone.

Can you post a side on picture of the 1.3TPI blade - I am curious as to the gullet depth and width.

Hi Nigel, I have a 1inch woodmaster B on my bandsaw ( Hammer N4400 ) I had similar issues to what you are describing. Turns out it was the tension, I now wind it up to nearly maximum ( way past what the gauge indicates is the correct tension ) and the blade works fine.
It does have a pretty wide kerf.

The solution to most bandsaw problems (other than the blade being blunt and things like that) seems to be tension of the blade. There are formulas that involve measuring the stretch of the blade to calculate the correct tension. From what I have read while solving the problems with our bandsaw mill (we can cut a 900mm diamond log 6M long) most bandsaw "tension gages" are woefully inaccurate. In our case we (actually just me) used a set of digital callipers clamped to the blade and set at 100mm. I then tensioned the band until I got 2mm stretch This was the calculated stretch for the blade we were using. To get that tension I had to exert 32ft.lbs torque on the 19mm fine thread metric tension bolt. Saw cuts like a beauty now but we have to keep checking the tension because it slackens off as the blade (which is about 6M long) expands with heat when cutting. Then we have to slacken the tension screw when we finish cutting or something might bend or break. I was trying to think of the tension formula....Young's modulus....I think. Do some research. Invest in a calculator and an accurate measuring device and have fun.

Nigel, your poor cutting with the 3/4" is almost certainly due to not enough blade tension. The blade is flexing in the cut.

The other feature - possibly in combination - is that you are feeding too fast, which overloads the gullets. This is why re-saw blades have fewer teeth.

Further to the comments of OH, the Woodmaster wide blades are fairly thick, and require a LOT more tension than narrower blades. You are likely getting sufficient tension on the 1/2" but not the 3/4". It is possible that your bandsaw cannot achieve what is needed without bending the frame. My Hammer N4400, which is a brute, tensions the 1" carbide Woodmaster CT satisfactorily, but it possibly only just succeeds here. I would just add more tension to your blade and hope for the best.

Regards from Perth

Derek

Thanks everyone for your advice, much appreciated. I read somewhere about ‘wearing a new blade in”....I must try and find that info. And yes tension does seem to be fundamentally important......

Originally Posted by Old Hilly

The solution to most bandsaw problems (other than the blade being blunt and things like that) seems to be tension of the blade. There are formulas that involve measuring the stretch of the blade to calculate the correct tension. From what I have read while solving the problems with our bandsaw mill (we can cut a 900mm diamond log 6M long) most bandsaw "tension gages" are woefully inaccurate.

The bandsaw mill at the tree loppers yard uses an hydraulic ram with a pressure gauge and the blade is tensioned to 22,000 psi.

Hopefully here is a pic of the 3/4" blade..

Lol, funny you should say that Derek, it did appear to me that the blade was indeed 'bowing' vertically within the cut.....I wondered whether I was seeing things... I have a feeling you are absolutely correct Derek; this machine, despite the marketing claim that it can take a 1" blade, may not be able to produce the tension required for this blade to operate properly. I would hate to destroy the darn thing especially as the 1/2" inch blade works beautifully. I may experiment a little more at a later date, but the 3/4" blade seemed to be very tight to me when obviously it was well short of where it needed to be to operate as happily as the 1/2" does.
Many thanks.

Picture of blade looks fine, as others have said it increasingly sounds like a tension issue.

Originally Posted by BobL

The bandsaw mill at the tree loppers yard uses an hydraulic ram with a pressure gauge and the blade is tensioned to 22,000 psi.

Bob, that 22,000 PSI could well be a figure taken from "Youngs modulus of elasticity" where the steel is tensioned to many thousands of pounds per square inch of tension. You then need to divide that figure by the actual part of a square inch that is the area of the blade measured at the gullet to get the actual tension put on the blade. Many of the US made bandsaws have a hydraulic ram (basically a "port-poert setup) with the pressure gage re-calibrated to suit the Youngs Modulus figures. This allows different blades to be used with the pressure set to their manufacturers specifications. God help me if we change blade types on our mill!

I run about 7x 3/4" woodmaster_B 1.3TPI blades on a Wadkin BZB20, which we get about 6 re-sharpens out of each. I re-saw various species up to around 200mm to 250mm depth most days and they do a very good job. I also cut 250mm thick tree branches lengthwise where they do an excellent job. The blade on this machine is primarily a breakdown blade rather than a resaw blade

I run 3 or 4 3/4" woodmaster_B 1.3 TPI blades on a 3hp woodfast horizontal bandsaw (same resharpening protocol). They do fine as well. This machine is for slabbing small trees, up to 400mm wide and 1.5m long. I do get drift when the tree is hard, like Mulga, Gidgee or Crowe's Ash. This machine has quite poor guides as they are made from local hardwoods. This machine was designed as a resaw for blades with small teeth and a large spine. The large teeth and small spine of the 1.3TPI blade are notsuitable on this machine unless the guide blocks are specifically manufactured for this blade.

I run a 3/4" woodmaster_B 1.3TPI blade on my personal H&F 2hp 16" BP16A , it cuts like a demon. No problems at all

I supply 3/4" woodmaster_B 1.3TPI blades to one of our members who cuts box kits for me on his 1.5HP Rikon 10-326. I set his machine up first time,but he does it now, He reports it cuts fine.

All blades are subject to drift if incorrectly tensioned.

The method I use to tension the blade is to set it so there is about 6mm of deflection on the spine side without "turning your finger white". On the wadkin's scale this is on the 19mm mark (its one of those odd imperial/metric machines). Once I have the blade tensioned, I then track it so the gullet is just in front of the crown. I then test the direction of cut. I do this by getting a piece of scrap pine an inch or two in thickness ,jointing one side, marking a line parallel to the jointed side then cutting freehand down the line. I stop the cut halfway through to see the natural line of the cut (using the jointed side as a pointer), I might move the bade tracking around a bit till I'm feeling happy about it, then reset the fence to be parallel to the jointed side.

If this does not get rid of the drift, there are 2 ways to get the blade to change the line of cut.
If you increase tension, the blade should cut toe-in, so if the work piece is pulling away from the fence, you have too much tension on the blade, ease off a little and re-test. The reason for this is that tensioning the blade causes the frame to flex a little. Different frames flex differing amounts.

The other way to change the direction of cut is to move the blade forward or back on the tire. Forward produces toe in, back on the tire produces toe out so if the wood is wedging into the fence and bending the blade away from the fence, you might want to reduce some toe-out. Using this method means you must check and reset the guides, as you will certainly have changed the thrust guide gap to the blade.

The other major thing which causes drift is incorrect guide adjustment.
If you have the thrust guide up too far forward, the blade will have a forward curve, the thrust guide will act as a fulcrum and the teeth will point either to-in or toe-out in an un-predictable manner. The thrust guide must be gapped behind the blade to allow the blade to curve backwards, so the back of the blade effectively acts like a rudder (not a canard)

If you have the thrust guide correctly gapped the side guides then function to limit rudder "flutter" on the back of the blade. A problem which can arise is that one of the side guides might be deflecting the back of the blade so that it no longer points true. This can easily happen because the post carrying the upper guide rarely runs parallel to the blade, so the setting of the side guides will be quite different at the top of the posts travel to the bottom. In practice I set it when the post is 3/4 down,as a good intermediate/avg setting, but if I am making an important cut, I set the post at the required height, then reset the side guides. I then do a test cut to see what is going to happen, mostly to make sure I know I got it right.

Try playing around with the saw to induce/reduce drift of different types.
hope some of this assists in understanding what the saw & blade are doing

Thanks for the info T91, there is some stuff in there that could well be rather important when I get the chance to actually use my little Hafco bandsaw.