Thread: Problems with resawing red gum

thanks for the link, bosox, it complements his FWW #173 article I referred to above.

Looking at the wheels this morning, and trying to work out how to further improve the resawing performance, I found a 10mm wide track of hard set resin around the upper and lower tyres, some of which would be under the blade. I took it to be just dust while playing with tracking of the blade. Took about 30min to soak it and then scrape it off both wheels. Will wait for it to dry.

Dengu,
The very nature of a band saw , it will leave a sterated finish, if you consider that you have multiple teeth moving in a vertical plane, against an object being pushed through the plane, then you will get vertical grooves.

The finer the grooves the better of course, , you will not get the same finish as from a circular saw,

Post a couple of pictures of the timber after cutting, and it will give us a better idea as to the finish.

Jeff
vk4

Thanks Jeff, I was expecting too fine a finish cut, being used to previously doing all my work on a tablesaw. Still have to change the blade and put a new one on, then will re-test for drift and will do some cuts and post the pics.

I have also seen a cover page for an FWW article which shows the serrated edge of resawn boards, and I think mine are not too far off that , even with the old blade (see attached, on LHS)


resawn boards.JPG

Hi Dengue: I haven't seen anything about your blade tension.

One person in a video tensioned the blade until it looked straight to the line of sight (he stood on steps to check), and then he tightened by one more turn. Snodgrass in his video tightened the blade until the blade only deflected slightly to a tap with the fore finger. I recently tried both those things, but in both cases the blade was so loose that it was rattling inside the return blade cover!!! So I did something incredibly brave: I tightened as above and retracted all blade guides and set the blade tracking as suggested by Snodgrass. I made sure that the tracking was stable by turning the wheels by hand several times. Then I turned the saw on WITHOUT THE COVERS ON to see what happened. I found that the tension was so low that the blade was vibrating like a guitar string. The deflection was like 2-3 cm wide. I turned off the saw and tightened the blade, turned on again and watched. then repeated until the vibration stopped. I then tightened by one more turn. I marked the position of the tension screw with a permanent marker and put the covers back on. You would be surprised at how much tighter the blade had to be! I have seen a video that when not tightened, the blade can even wander within the piece!

Hi everyone, here are the results of my latest effort today, after removing the rubber tires and scrubbing them clean in water with a scrubbing brush.

I then installed a new 13mm x 3 tpi bimetal blade and lowered the speed by messing around with the drive motor pulley belt. I firmly tensioned the blade, as recommended by GarciaJ above, and it ran freely without vibration or noticeable deflection.

I then spent some time checking the blade drift, and changing the blade tracking on the flywheels until there was zero drift. This took a while. The blade was at right angles to the table in both planes, and I installed a 200mm high melamine fence bolted to some 50 x 6mm AL angle to keep the fence at right angles.

I tried it out on a piece of red gum offcut that had been used for stairs in an upmarket house that my nephew was working on. The board has 250 x 30mm cross section, and the shortest side measures 450mm. I think that this is fairly onerous duty for this poor old Elektra Beckum BAS500 bandsaw.

I have attached photos of the finished cut. The deepest corrugation would be about 0.5mm, and the variation in the side thicknesses of the resawn boards were less than 1mm throughout. After cutting the board did bow, as shown in the last picture. I think the worest corrugations occurred after I stopped pushing the workpiece a ouple of times. Would this be the probable cause?

Can anyone please advise if this is the quality of finish that I should expect? Looks OK to me ,and won't take much effort on the thicknesser to remove 1mm of each of the resawn sides


P1130213 (Medium).jpgP1130214 (Medium).jpgP1130217 (Medium).jpgP1130218 (Medium).jpgP1130224 (Medium).jpgP1130219 (Medium).jpgP1130222 (Medium).jpg

I'd be happy with that, I get similar on my BAS350 and yes to the corrugations, the trick is to get that sweet spot which is a consistent feed all the way through, you'll also noticed on the angled bit that the marks are slightly different.

The one thing I've found is to listen to the cut and once you know the correct sound, you can adjust your feed to suit.

Ditto to that. And you could clean it up with a hand-plane.

Acco and pmcgee know best, but it looks good to me too... I'm told that it's the straight cut and even thickness that you need to be looking for rather than a perfectly smooth finish, and pictures 6 and 7 seem to suggest you are getting a straight cut and even thickness. By the way, in his video Snodgrass would have you believe that "blade drift" is not important. I am too much of a novice to have formed an opinion on this.

The finish you are getting is not too bad, I took some pics of a comparison between the woodmaster B and the CT, the B being a bimetal with a left/straight/right 1 tpi (raker? configuration from memory) and the CT being the woodmaster tungsten carbide blade, no set on this blade but with an alternate straight/triple chip grind, the B certainly gives a coarser finish (from the set of the teeth) but is free of lines, the CT blade gives a very smooth finish, in the pics tho there are some spaced lines which normally
shouldn't be there, I think I had a tooth sticking out, probably from some sort of operator mishap
long shot B blade.JPGlong shot TC blade.JPGTC blade closeup.JPGcloseup of crotch figure.jpgB blade.JPG

I hope everyone can work out the order of the pics above, I was trying to put them in order but too frustrating, once I had one pic in the thread I couldn't put the cursor where I wanted, it wanted to be up at the first word, and smileys seem to give grief as well, as does the pic loading process, aarrrrgggghhhhh, I do like the auto save feature tho.

The brown one is some raintree, I cut this green, I think with the B blade, a smooth finish with some faint lines.
When cutting green stuff there is a tendency to get build up on the blade, this will cause vibration and will give the wavy line pattern we see in Dengue's earlier pics, it will also be a lot noisier, one of the best finish blades I have used is the woodslicer from Highland Woodworking especially when sharp, IMO everything else follows after a sharp blade.

Pete

Originally Posted by pjt

I hope everyone can work out the order of the pics above, I was trying to put them in order but too frustrating, once I had one pic in the thread I couldn't put the cursor where I wanted, it wanted to be up at the first word, and smileys seem to give grief as well, as does the pic loading process, aarrrrgggghhhhh, I do like the auto save feature tho.

The brown one is some raintree, I cut this green, I think with the B blade, a smooth finish with some faint lines.
When cutting green stuff there is a tendency to get build up on the blade, this will cause vibration and will give the wavy line pattern we see in Dengue's earlier pics, it will also be a lot noisier, one of the best finish blades I have used is the woodslicer from Highland Woodworking especially when sharp, IMO everything else follows after a sharp blade.

Pete

Hi Pete.

I had the picture order problem also re my 'workbench' ...despite uploading them in a particular order. In the end I uploaded the pics, deleted them from the lower box and then dragged them back into the lower box from the upper box in the order I needed.

However, in the lower right corner of the slide-view people can see the file-name of your pics, so it should be pretty clear what each picture is of - because your file-names are descriptive of the subject.

I talk about handsaws quite a bit, and the smoothest finishing handsaw I have has close teeth (12ppi) and very little set - so I have wondered previously about set in bandsaws blades and how smooth a finish should be possible.

Could you tell me, or photo, the TC blade you mentioned please? I am familiar with the L-R-straight blades, but interested to know about others.

I will read back and check - but what width blades are yours? and the OPs?

Thanks,
Paul

PS - I get the Autosave popup, but have no idea yet how it helps. I was bitten with a lost post months and months ago and often copy the contents of my posts before pressing "the button" ... just in case.

PPS - ok - OP = 13mm x 3tpi bimetal

Originally Posted by pmcgee

Hi Pete.

I had the picture order problem also re my 'workbench' ...despite uploading them in a particular order. In the end I uploaded the pics, deleted them from the lower box and then dragged them back into the lower box from the upper box in the order I needed. Thanks for the tip, will try that next time, the next hassle is looking thru picture folders each time another pic is browsed for, the old version used to remain at the same folder to select more piccies from, I have all my piccies organized into folders so I know where I am, it might be me as well!!!!

However, in the lower right corner of the slide-view people can see the file-name of your pics, so it should be pretty clear what each picture is of - because your file-names are descriptive of the subject.

I talk about handsaws quite a bit, and the smoothest finishing handsaw I have has close teeth (12ppi) and very little set - so I have wondered previously about set in bandsaws blades and how smooth a finish should be possible.

Could you tell me, or photo, the TC blade you mentioned please? I am familiar with the L-R-straight blades, but interested to know about others. I'll take a pic, I might need a reminder if I haven't in a day or two tho, but basically it has a straight then a straight again but with both outside corners taken off at about 45°, this would leave wood behind in the btm of the kerf which would then be taked out by the straight tooth, I guess this reduces the load per tooth to some degree.

I will read back and check - but what width blades are yours? and the OPs? The B blades are 1 1/4" the TC are 1" and the woodslicer is 3/4" wide, the woodslicer has a variable pitch 3 to 4 tpi which reduces vibration which then gives a smoother cut and it is smooth

Thanks,
Paul

PS - I get the Autosave popup, but have no idea yet how it helps. I was bitten with a lost post months and months ago and often copy the contents of my posts before pressing "the button" ... just in case. Ummm yeh I ave lost a few posts as well, typing typing typing blah blah with pics loaded, do a preview and then some glitch either at my end or the other and all lost, aaarrrrgggghhhhhhh, to quote Charlie Brown but the auto save saves it along the way in case that sort of thing happens, well at least that's what I think happens?.

PPS - ok - OP = 13mm x 3tpi bimetal

Pete

It’s nice to see those improvements with your cuts, Dengue!