Bandsaw blade help!!

[woodbloke65]

The front to back verticle is important if you want good cutting. It does not need to be 100percent, but it helps. If the blade does not move forwards or backwards under power, without guides or thrust bearing in position, then its as good as you will get, but tuning for this is important. AS it is in your last photo, the wood will be cut at the lower connection first.

Malcolm

Agreed. The blade should be square to the table front to back and also at the sides. If it's not square front to back, it may mean that shimming or packers (thin washers) need to be introduced underneath on the trunnion bolts to raise the table slightly. It's fiddly, but doable - Rob

 

[Hornbeam]

You have 2 separate problems.
Squareness of the blade side to side. As the blade is effectively a straight line and if the table is flat any discrepancy in the angle on one side would be reversed on the other. As this is not the case, the table cannot be flat or the insert is slightly proud. A straight edge across teh table will check this. If you set a flat straight section across just behind the blade and shimmed a few mm off the table on both sides you can check again with your square and this eliminates any slight out of flatness of the table (the blade may not be square but the error you see on one side will be equal and opposite to the other.
Squareness front to back. This looks a long way off. Have you checked where the blade is running on the top and bottom wheels. I would slacken all top and bottom guides off and see if the any of the error can be adjusted out. Shimming the trunnion blocks on the table may be required but you could be adjusting one element to compensate for something else. It is best to go back to what fixed reference points you have
Ian

 

[undergroundhunter]

We have a calibrated straight edge at work i will bring it home and check the table with the insert in and then again with it out.

Thanks guys

Matt

 

[undergroundhunter]

Ok so I checked the table with the straight edge and I can see light in the middle, unfortunately I forgot to bring my feeler gauges so I dont know how hollow it is, I will try to remember to bring them home tomorrow and find out exactly how bad it is.

Matt

 

[Ttrees]

I suggest to try shimming the table so the back of the blade is square to the table .
This squareness is important for cutting tenons for example.
I would try to focus on shimming just the low side of the table to see if the problem can sort itself out.
Biscuit tins make good shims ..I guess they are a fairly even tolerance.
Tom

 

[undergroundhunter]

Biscuit tins make good shims ..I guess they are a fairly even tolerance.
Tom

I have been pondering today about what to use for shimming, you sir have just answered my question.

Matt

 

[Ttrees]

You might need to try with thin washers attempting to lift that side of the table though, and then fine tune with the tins.
It probably will move when you do, so I would not go too mad trying to get that side level with the other one straight away
give it some time to move, and don't over tighten anything .
The tins should tell you how much your table is out at least.
Hopefully the shimming will sort out both issues at the same time.
Otherwise I would be looking for a new table .
I seem to recall RP not liking you to do any adjustments, nor putting these kinda things up on forums!
Make sure to have photographic proof of how much the deviance is, before you start .
the tins should have all the burrs filed off to be accurate

 

[Arkhan]

Hi there. No need to immediately use washers. I had similar problems with my bandsaw. The Bs400 has tiny adjustment screws at the trunnion which you can adjust with an Allen key to make the table tilt in the right direction. They're easy to overlook but they should be there. It'll take a while to get everything right but it'll work in the end. Or should. Once I'd discovered them I immediately removed the washers/shims I had in place till then.

 

[undergroundhunter]

Hi there. No need to immediately use washers. I had similar problems with my bandsaw. The Bs400 has tiny adjustment screws at the trunnion which you can adjust with an Allen key to make the table tilt in the right direction. They're easy to overlook but they should be there. It'll take a while to get everything right but it'll work in the end. Or should. Once I'd discovered them I immediately removed the washers/shims I had in place till then.

Thanks for that I will have a good look later.

Matt

 

[Arkhan]

Thanks for that I will have a good look later.
Matt

You're most welcome. They're really tiny grub screws. You'll find them at every corner of the trunnion.

 

[undergroundhunter]

Are then on the table side of the trunnion or the machine side? looking at the exploded diagram I think it must be these (in red) is that right?

Matt

 

[Alexam]

Se the diagram from transatlantic - record-bandsaw-bs300e-squaring-blade-to-table-t101089.html

 

[undergroundhunter]

Se the diagram from transatlantic - record-bandsaw-bs300e-squaring-blade-to-table-t101089.html

Thanks for that I will have a closer look in the morning, I did look earlier but only really looked at the parts that contact the table (stupid I know).

Matt

 

[Arkhan]

Yes, they're the ones.

Are then on the table side of the trunnion or the machine side? looking at the exploded diagram I think it must be these (in red) is that right?
Matt

 

[Eric The Viking]

Just seen this thread: My bandsaw table has a raiser block made of MDF, to create enough room underneath for dust extraction above the bottom bearings. But MDF isn't solid it's squishy (to an extent). And, like your bandsaw, the slot for blade change is to the front of the blade.

It's very common that, after I've swapped blades over, the two sides of the blade change slot don't end up parallel to each other. On side will be twisted upwards and one downwards. If I put a square on the table, and against the blade, I get similar results to you - oddly one "side of the blade" seems true but the other doesn't.

It's becausde the table is distorted by uneven tension in the bolts that hold it to the trunnions. And I can get that because of the spongy nature of the MDF. I can fix it through paying attention to several things:

1. checking that the rail for the fence is fitted properly and done up tight. It clamps underneath the table (on mine), and helps to hold both sides flat and parallel to each other.

2. releasing the tension on the four bolts to the trunnions and slowly tightening them up in pairs (front pair and back pair). I do have a low value torque wrench (a Norbar, intended for motorbikes). I ought to use that really. Actually I ought to replace the raiser block now, with something more solid, as I find I have to shim it asymmetrically.

I can't easily get the front back angle of the blade to stay at 90deg to the table, this is because it changes as the tracking is adjusted: the top wheel has to move!. It's close enough and as long as the side-to-side thing is sorted, there's rarely an issue.

You might find it easier to check with a Gem Red digital level (other brands, etc.). It's one place where it's very useful (also for setting tablesaw tilt). mine works to an accuracy of 0.1 degree, which is good enough for most things.

 

[undergroundhunter]

Just for the record (no pun intended) I have measured the flatness of the table just behind and just in front of the insert, I have a gap of 0.15mm under the straight edge at both so I think that's pretty good, unless anyone thinks otherwise? To be honest now I have set the table using a 24g I'm happy with that aspect I just need to sort the squareness to the back of the blade.

Matt

 

[Eric The Viking]

I just need to sort the squareness to the back of the blade.

And I said...

I can't easily get the front back angle of the blade to stay at 90deg to the table, this is because it changes as the tracking is adjusted: the top wheel has to move! It's close enough and as long as the side-to-side thing is sorted, there's rarely an issue.

I didn't make myself very clear: the front-back angle of the blade to the table changes with blade tension and tracking. The effect is a lot less on bigger saws (but sadly mine is only 12").

You might shim the table; you might also improve it by altering the position/alignment of the bottom wheel (depending on how that is fitted - I understand some don't have adjustment). The trouble is that, with a steel-box-section frame, it is educated guesswork. You can only make the really fundamental adjustments without a blade in place, when the frame is not under tension.

If you think of the frame as a capital "C", the forces act in two ways: The obvious one is to pull the two arms of the C together so as to close it up. This moves the blade left-right across the table, it may also tilt it.

The not-so-obvious one is the twisting force exerted, because the wheels are hung off axles that stick out sideways from the frame.

Viewed from the front, as you increase the tension, the top guides move to the left and backwards. The table tilts so that the front moves upwards, and (left-right) very slightly anticlockwise. On my saw, with a 5/8" resawing blade fitted (the biggest that is sensible), the guide movement effect is really obvious.

None of the above is mentioned in Mr. Snodgrass's popular video. But he is using (selling?) bandsaws with cast frames, which are inherently far more rigid than 98% of the hobby saws available here. Setting up a box-section frame is far more complex than he would have you believe if you do it thoroughly. It took me around 1 1/2 days to get mine set up the first time I did it (after a thorough strip-down, clean and fettlement). I really need to do it again now.

By the way, It does seem like your table is dished or something. If your square is correct and you are checking left-right without the plastic throat plate in place, and the two sides of the table are aligned (totally coplanar) at the front edge when the fence rail is in place, then that is the most likely reason you get different "squareness" when checking from either side. Even if your square was off, if your table was dead flat you would see a mirror image of any error from the square itself when checking either side.

E.

PS: Given it's cast steel, it's remarkable how easily I can bend the table on mine. I usually slide the butt end of the engineer's square across the join from both directions to check it, all along the slot. If it catches, the thing is twisted.

 

[Alexam]

Are then on the table side of the trunnion or the machine side? looking at the exploded diagram I think it must be these (in red) is that right?



Matt

If you tilt the table to 45 degrees and look under at the base of the trunion, as long as its not covered with sawdust, as mine was, the two hex screws are easily visable.
Malcolm