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By Chris152
#1312751
When the blade is correctly positioned on the top wheel, it's practically falling off the bottom wheel.
I disengaged all guides and it improved.
All seemed fine running by hand, but once doors closed and motor started, it ran out of position on the top wheel altering the position of the blade in relation to the guides. Repeated a few times, same thing when the motor was used to drive the wheels.
Then I tried adjusting again with the motor running, but the tiniest movement on the control led it to wander way beyond what it does turning the wheel by hand.
Seemed odd, and for some reason I pressed down/ pulled up (not with a lot of strength) on the right side of the table. This happens (assuming I can get the vid to embed - I still struggle with the codes):

youtu.be/RzVjaZjgnBE
(https://www.youtube.com/watch?v=RzVjaZj ... e=youtu.be)
What on earth is going on?!
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By CHJ
#1312762
I believe you may have you setting priorities wrong.

The first priority is to get the blade running without any guides in a comfortable position on both wheels. (Not a specific front back location)

Check that at this stage it is running true 90 degrees east west and north south to your Table and in line with you mitre slot.

Adjust your top wheel tracking and/or adjust your table to achieve this but always maintain the blade in a reasonable position on the top wheel.

Bring up you blade guides to support it whilst cutting.

If you can now disturb these settings by loading the table suggests that the frame construction of the machine is not adequate.
By sunnybob
#1312772
What chas said. ALL the guides must be well clear of the blade when setting up. If you run the blade through the guides such that teeth go in between the wheels, youve killed the blade because youve squashed all the teeth in.

get the blade running steady. looking at it from front on to the teeth, increase the tension knob slowly until the blade stops vibrating and looks like it isnt moving.
Stop the motor. wait till the blade has stopped.
Adjust the side rollers so they are not quite touching the blade, and they are aligned with the rear third of the blade.
Adjust the REAR wheels so that when you push the blade back with your hand the wheel stops the teeth from going in between the side rollers.
Tighten up, and re check the teeth can not be pushed between the wheels.
You MUST do this each time, or your blades will be instantly blunt.
By Chris152
#1312819
Thanks both. I made a new wooden insert but no improvement. :-)
Repositioned all guides well out of the way, set blade on top wheel to where I wanted it, closed doors and it moved again. Blade at correct tension (tightened til no flutter).
Started it again, it moved again. Repeat (without opening doors or winding by hand) - moves again, as per:

youtu.be/aa9F-pOd5YI
https://youtu.be/aa9F-pOd5YI
Keeps moving, sometimes more than others.

edit - ps, I'm using a 1/4" blade for the first time. It's supposed to work with 1/4" on a RP350 but maybe it's an issue?
pps Fired it up once more, just to see if it'd stop being silly, and it wandered back into the black tape an, opening top door, this is where the blade has ended up:
IMG_2237.jpg
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By CHJ
#1312826
At which point is the blade at 90 degrees to the table, at the start of your video or at the end when it moves back.

Although in the last image your blade would appear to be riding too far back and not fully supported on the tyre, the actual position on the top wheel as long as it is fully supported and running true to the table is not critical.

Setting the position on the top wheel to Your preference without machine running is not the finite criteria, it only acts as a guide to ensure the blade is not likely to come off the wheel when started. Tracking setting should be done with the machine powered up.

What is the blade relationship to the table when you adjust the top wheel with the machine tensioned and running and the blade is sitting nearer the centre or front of the tyre.
By Chris152
#1312829
Side-to-side the table's 90 degrees to the blade. Front to back, the table's out in relation to the blade by about 1 degree, I guess. Adjusting the table for and aft is a nightmare on this saw and since I use it for cutting blanks/ currently reindeer rather than anything that needs a perfectly vertical cut, I've not tried to alter it in the past year or so. So the table doesn't help establish how the blade is oriented in relation to the rest of the machine.
edit - it was closer to 90 degrees when it wandered back, but on a subsequent startup it wandered forward again.
That's interesting about positioning with the motor running - I'd just assumed it was supposed to be done with the motor off. I have watched Snodgrass and all, but guess I'd forgotten.

As it happens, I just positioned the blade with the gullets on the crown, fired it up and it's staying put for the moment. Guides back in place, I'm going to do some more cuts. But - the lower wheel looks like this - which is less of a concern with a wider blade, but this one looks barely stable where it is:
IMG_2238.jpg

Is it ok like that?
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By Jacob
#1312832
Or try a different blade - they sometimes are a bit out of shape in not very obvious ways, and won't do what they are told. Or higher tension?
By sunnybob
#1312844
The blade has to be on the rubber on both wheels.
move the guides away again, loosen the blade, and spin the top wheel by hand. adjust the in / out while turning it by hand untill the blade is in the middle of the rubber. Tighten slowly, while still checking by hand.

Once the blade stays where it should be, you can do a quick test of tightness by twanging the blade just before it reaches the top wheel with your finger. if you get a flat note, tighten some more till you get a musical note.

Then shut the doors and see what the motor does. The blade should stay in its place. Now do the flutter test.
now readjust the guides.
MAKE SURE you tighten the lock nut on the front / back adjuster.

I use thin blades all the time on my axminster 350, and have no problems with this set up. On the top wheel, i have the teeth gullets just about midway on the rubber, this also translates to the bottom wheel as well.
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By Ttrees
#1312871
When you tension the blade it will migrate on the top wheel to the front.
Thats the way it should work.
I would first try to see if adjusting your tracking might sort this issue out with the bottom wheel.
If that does not work try a different brand blade.
If that fails also I would be guessing the lower wheel might have moved.
Are the Jacking bolts loose?

Tracking adjustments while a blade is tensioned may well damage the threads, so beware of that.
Thats easily an hours work
I hope you have a different brand blade to compare, as that one could be a bit warped now.
Tom
By Chris152
#1312873
sunnybob wrote: I use thin blades all the time on my axminster 350, and have no problems with this set up. On the top wheel, i have the teeth gullets just about midway on the rubber, this also translates to the bottom wheel as well.

Mine's never really done that on the lower wheel, tho I can't remember how it was when new (about 2 years). It's certainly been positioned toward the front the past year or so, but it's not bothered me with wider blades that the teeth are slightly off the rubber as so much is still on the rubber.
But this strange wandering across the top wheel is new today, and my first use of a 1/4" blade.
I've just got back from jumping in the sea which is now getting chilly and I'm warming up with a glass of wine, so best leave til tomorrow. It was fine on the last trial so I'll have another go at cutting, then follow your steps exactly if it starts wandering again SB.
Thanks to all.

ps Tried to post and yours appeared, Ttrees - if it wanders tomorrow, I'll try another blade to see what it does. I have a new 3/8ths one so will put that on. Cheers.
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By Ttrees
#1312883
Is it a different brand though?
I was so surprised that it would make so much of a difference after trying differing types from the same supplier.
By sunnybob
#1312921
I've watched bandsaw blades made. Its very simple (with the right machine), but If the person doing it is careless there are a a few opportunities for the blade to be twisted.
Easy way to check is find a flat piece of concrete or tiled floor and lay it down, if its bent you will see it doesnt lay flat.
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By Ttrees
#1312922
I could show you a good few blades Sunnybob and you wouldn't be able to spot anything wrong with them, not a hint.
Cant tell you why the won't track right, its a bit baffling to be honest.
Huge variation on where they sit on the wheels, it really surprised me.
By Chris152
#1312947
I don't want to think about that possibility, Mike! Fixing that's definitely above my pay grade. But I've been wondering if that might be it. That said -
Could having the blade over tensioned cause this? I just took the 1/4" off to check for warp (seemed ok, not sure how flat the concrete floor is) and replaced it with the new 3/8 blade, which tracks much better (sits forward on the lower wheel but teeth entirely on the rubber), and noticed it was over-tight for that - so presumably far too tight for a 1/4 blade. I must have just used the quick release lever to tighten it up and forgotten to reduce tension.
Just wondering if this could be it in principle, I'll go and try it out.