Grinding / Polishing / Small chips

[Julian 'Farmer' Bonsall]

So I purchased an electroplate 115mm grinding disc. I had an already cut floor tile (with glaze chips) to try the new tool out on. I also compared a segmented blade (for stone cutting), a Marcrist CK650SF (110mm x 1.7mm), and a Marcrist CK650 (115 x 1.1mm).

Images : Grind disc, 3 x cut discs, precut floor tile, cuts with 3 blades, after grind top, after grind cur face.

I did attempt the wet sponge (you may see damp tile) but I don't think I had it wet enough.

I have found an issue with the grind disc. If the direction of grind is from the glazed surface towards the biscuit its very good (I am not quite so keen on the actual shape of the disc - flat would be my choice) but if one grinds from biscuit to face then I had some surface chipping. I am not sure if this would happen with a pad/paper solution. Where you have an 'L' in a tile it could be tricky to always grind from the glaze.

 

[Concrete guy]

I have found an issue with the grind disc. If the direction of grind is from the glazed surface towards the biscuit its very good (I am not quite so keen on the actual shape of the disc - flat would be my choice) but if one grinds from biscuit to face then I had some surface chipping.

That's quite normal, think of it the same way you would cut a piece of timber, you always cut into the finished surface so it's doesn't splinter. As opposed to cutting up through the finished surface

A flat blade would be unforgiving, they are called electroplated vanity blades and designed more for marble and other soft materials.

 

[Flintstone]

The slots you have cut there have some bad chipping, I never get chipping like that with grinder and wet sponge, I use ats blades, mainly the turbo blade, cut slow, two passes, persevere with the sponge it makes all the difference.

 

[Julian 'Farmer' Bonsall]

@Localtiler understood and thank you. I will give the sponge some more practices. I would much prefer a bigger 150mm disc and maybe have more space for the sponge.

The thin slot you see was done with a wet sponge and slowly (they were all done as I normally cut) I also wet the tile with a small puddle around the blade as I was struggling with the sponge, I should have videoed it really (even for comedy value) - I chose that tile as it chips like no other (and being a dark tile I thought better for images) I have cut and it was to demonstrate the new electroplate grinding disc. One of the cuts is completed with a blade normally used for motor and brick work.
I chose the CK650 over a Premtool Turbo Fastline as I took it as preference on the kitchen I did recently. I can repeat with the Premtool blade if necessary.

 

[Julian 'Farmer' Bonsall]

A flat blade would be unforgiving, they are called electroplated vanity blades and designed more for marble and other soft materials.

Thanks for the quick delivery and the help and advice. It does just what you suggested - as hopefully can be seen it cleaned up the badly chipped tile a treat.
I don't understand what you mean by a flat disc would be unforgiving? I have always used the side of a disc in the past to clean up the edge which is flat? I have in the past held the tile perpendicular to the disc and removed the biscuit until I get a clean face on the glaze. Maybe that is not correct? With the curved face this technique would seem to not be the best.

 

[Flintstone]

I think he means a flat side like the montolit has will rip it up on the upstroke, when the wheel is coming back up

 

[Julian 'Farmer' Bonsall]

@Localtiler ok think i understand - but that's how I have use the side of my cutting disc to grind in the past. Disc perpendicular to the tile surface, disc touching biscuit and ultimately glaze - outer radius/rim of the disc slightly protruding the glaze. It has worked well for me but my concern was I am wearing out the side of a blade in a way it wasn't meant to. With a backing pad / paper are they not used in this way? Or are they used at an angle across the tile face? Sorry for not understanding.

 

[Concrete guy]

I think he means a flat side like the montolit has will rip it up on the upstroke, when the wheel is coming back up

Exactly that, the curve allows you to be quite accurate with the cutting surface. A 125mm Flat vanity blade is touching 125mm of material pretty much all the time.

 

[Julian 'Farmer' Bonsall]

Sorry to be thick but isnt that whats happening when I use the side of a cutting blade? Why is that a bad thing? (you can always move the front or back face away?). A 125mm disc will only touch on the coated band and if the blade is circumference is slightly protruding the surface of the tile then there wouldn't be a lot of contact (depending on tile thickness) ?
Would a video of how I use the blades help to explain what I mean?
I just felt I would want a flat blade but maybe I am not using it correctly?

 

[Old Mod]

Would a video of how I use the blades help to explain what I mean?

Yes it would.

You keep saying you hold the blade perpendicular to the tile, and that you’re using the side of a cutting blade to tidy an edge.
That would mean you’re holding the blade parallel to the tile
To hold something perpendicular, would mean to make a T shape with blade and tile.
And if you are ‘toeing’ in the front of the blade, or indeed the back as you describe, then a slightly convex blade would do this for you.
Which is exactly how the grinding blade is designed.
These processes don’t take 5 mins on a sat afternoon to perfect, they take time and many lineal metres to get even half right.
As far as blade catching the glaze on the ‘up stroke’, of course it will, that’s not a revelation.
Any kind of sanding/polishing action is done in the direction of the grain and with the rotation of the blade. You should move in one direction, so that the downward rotation cuts through the glaze first and then the biscuit.
It’s no fault of the blade that it catches the glaze on the way back up, it’s down to incorrect technique.
Sorry if that sounds harsh, but that’s what it is, incorrect technique.
If you can make a flat blade work for you, then that’s great.
And every single tile behaves differently to the last, if they didn’t, then we’d all use the same blade, but we don’t
The effectiveness of any blade is down to two things, material and technique.
There is no one answer, it’s a subject that changes every day, with the introduction of different materials and different blade technology.