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The cutting of Porcelain tiles, 16mm, with a Vitrex bridge saw, has been very successful, holding cuts of 900mm to 0.4mm.

BUT

All the blades I have tried, ATS, Marcrist and Rubi, have all started to cut off centre.

I have dressed the blade with a Rubi cleaning block and this will improve cutting but it doesn't seem to cure cutting off centre.

For some reason, after a load of cuts, the blade will start to deviate from where the machine carriage is going. At the end of a long cut, it can be as much as 2-3mm off centre and you can see the blade flexing sideways.

My theory as to why this is happening is that the edge of the blade, although 'sharp' with plenty of exposed diamonds, is no longer square. It's rounded and the rounded edge is not even.

Of all the blades I have tried, Rubi TVH was the worst. It cut the best, with lower noise, less chipping but didn't last half a day before it started to wander off.

So am I right is thinking I need to square up the blade? If so, how?

The blades seem to cut through the cleaning/dressing stone really easily. Do I need to make the cut into the dressing stone more quickly?

Do I need to dress the sides of the blade?

Is there some other way to recover the blades? Thay all have lots of edge left, it's just not square...

Any advise muchly appreciated!
 
C

Concrete guy

Are you sure it's the blade deflecting and not the entire axle on which the carriage is running? I used to own a RUBI bridge saw which was known for this, in fact I think they still do it.

It only needs to deflect slightly then the blade wants to wander off line. Once off line the blade will continue to wander and accentuate the problem.

The fact it's happening with all types of blade would suggest there's an outside factor involved.

16mm porcelain paving is about as hard as it gets for a tile saw. The Vitrex machine you have is entry level as far as bridge tile saws go, so I'd imagine you're at the limit or possibly beyond the limit of the machine. Specifically the power of the motor and blade diameter.

Try slowing down the cut speed, if this creates a straighter cut (even if it wanders less) then it points to the capability of the machine.
 
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D

Dumbo

Tbf when I use a bridge saw I don't just set it and run it., I watch the blade through the cut and move the tile accordingly
 

Dan

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I used to work at Topps tiles and as a newbie there you always did the wet cutting, which was a service they'd offer to DIY so they'd spend more on tiles.

I can't ever remember using the guide with success. Always had to free hand it and guide it myself.

Pushing too much will make the axel move eventually. So perhaps put a lot less pressure on it. The fact you've had the same results with loads of blades would suggest it's the machine and / or operator :)
 
OP
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I used to work at Topps tiles and as a newbie there you always did the wet cutting, which was a service they'd offer to DIY so they'd spend more on tiles.

I can't ever remember using the guide with success. Always had to free hand it and guide it myself.

Pushing too much will make the axel move eventually. So perhaps put a lot less pressure on it. The fact you've had the same results with loads of blades would suggest it's the machine and / or operator :)

The machine cuts dead straight, to 0.4mm over 900mm, for maybe 20-30 cuts. Then the blade walks off to one side by 2-3mm.

At that point the blade is knackered. It will continue to produce curved cuts.

There's no way you could get a stright cut by 'moving the tile', it's 25 kg for a start!

The issue is the blade getting degraded.

I just don't yet know how to get the blades back to normal.

I suspect they need to be squared up somehow.
 
C

Concrete guy

So based on that I'd dress the blade every 10-15 cuts. See if that makes a difference.
 
OP
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Time for a new saw
New saw blade? The machine cuts dead straight, the blades don't after a days's cutting....
[automerge]1562277818[/automerge]
So based on that I'd dress the blade every 10-15 cuts. See if that makes a difference.
Is there a specific technique for dressing the blade? Just take a cut straight through the cleaning block? Does it need to be a fast cut?
 

Bopster

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I’d be looking at changing machine to a track saw system like TC 180.
That will give the result your after, zero run out and able to cut in depth increments to stop the blade degrading
 
OP
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I’d be looking at changing machine to a track saw system like TC 180.
That will give the result your after, zero run out and able to cut in depth increments to stop the blade degrading

Hi Bopster,

I could, if I have to, make the machine settable with a shallow and full cut, if that helps.

But I really don't think it's the machine, as it runs true and with a fresh blade cuts perfectly.

Is there something about the machine that could make the bades decide to cut off line?

When the blade has gone off, the machine is still tracking straight. It's the blade that wants to cut off in one direction. At the end of the cut, the machine will be still bang on the line but the blade will be flexed over 2-3mm off to the side.

This is why I think the problem is something to do with how the blades wear in the really hard Porcelain. If the blade wear is uneven, it's going to start to want to track off sideways?

I noticed one blade had an edge that was off centre.

blade edge.jpg

This is what the blade does. Initially the blade will cut straight be then gradually veer off until at the end of a long cut, it's flexed over. The machine tracks dead straight and the blade is dead square. I've checked it with a dial gauge.

blade flex.jpg


This
 
D

Dumbo

Something is wrong with your machine that makes the blade wear in that fashion and it causes it to cut off line . How can a number of different blades be wrong . Even though your carriage runs true your saw must be attacking at an angle . Put a straight edge on the blade, along the length of the bed and see how that looks , or stop messing about and get something better than a vitrex , you can't spend diy money and expect consistent professional results .
 
C

Concrete guy

You've already explained you've shimmed part of the machine to make it run true.

@jcrtiling is explaining that the shimming, whilst making the carriage run straight may have altered the angle of attack of the blade causing it to want to cut off line. If the blade isn't perfectly parallel with the motor housing, which in turn is perfectly parallel with the rail then you're not going to cut straight with any blade.

You're looking for a perfect result that a Raimondi Pikus would produce with a machine that costs 10% of it's price.
 
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So based on that I'd dress the blade every 10-15 cuts. See if that makes a difference.
Time for a new saw
You've already explained you've shimmed part of the machine to make it run true.

@jcrtiling is explaining that the shimming, whilst making the carriage run straight may have altered the angle of attack of the blade causing it to want to cut off line. If the blade isn't perfectly parallel with the motor housing, which in turn is perfectly parallel with the rail then you're not going to cut straight with any blade.

You're looking for a perfect result that a Raimondi Pikus would produce with a machine that costs 10% of it's price.

OK, so the machine is causing uneven blade wear and once that gets bad enough, the blade starts walking off. Correct?

I will double check the blade squarness to the rail again.

The motor is shimmed to get the blade square to the rail, to about 0.1mm across the blade. Out of the box, the motor was miles out of square and the blade chipped badly.

The Rubi TVH blade produced lovely clean, straight cuts but after half a day it started to drift.

The accuracy of the cuts is very good and very consistant for a lot of cuts, so it must all be running reasonably true.


Is there any way to get the blades back true?

At least if I can do that, I can use them for a day to too before having to re-true them until the edge is depleted.
 
C

Concrete guy

Dress them more often. In theory that will not allow them to start running out. There's no point waiting until they aren't cutting, keep them sharp.

Your fighting a battle against a machine that's clearly not running straight in one way or another. So your real world options are replace the machine or dress the blades more often.
 
OP
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Dress them more often. In theory that will not allow them to start running out. There's no point waiting until they aren't cutting, keep them sharp.

Your fighting a battle against a machine that's clearly not running straight in one way or another. So your real world options are replace the machine or dress the blades more often.

OK, I will try regular dressing.

I'm sending the Marcrist back for them to look at.

This is a good example of the machine cutting 900mm slices, it will usually hold 0.1 to 0.4mm over 900mm:

slice.jpg

And this is a few 150mm cuts in a tile. Three cuts from the Marcrist with dressing inbetween on the left and one from a used ATS blade that's still working 100%, all done one after the other. (the lens makes the lines look bowed but they aren't)

20190705_165631_001 (Large).jpg
 

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