Masonry cutting sawbench

From DIYWiki

Introduction

This is a quick'n'dirty project to turn an angle grinder into a masonry cutting workbench

Why?

The first project is to clean the mortar off a pile of reclaimed bricks that have now been taken out of the wall they were in when it fell over.

The wall fell over in a storm. So having set about it with a concrete breaker, we now have a large pile of bricks

Now there are several ways of doing this; chipping hammers, scutch chisels etc, or even using a grinder and diamond disc free hand. However most of these require taking the tool to the brick, and holding the brick in some way while you process it, and hopefully not breaking it into too many pieces during the process. I figure this could get tiring and old quickly! So what better than some kind of table saw setup for masonry cutting?

Now there already exist a whole class of masonry cutting bench tools - usually sold as tile cutters. These typically include some kind of motor to spin a diamond edge cutting disk, and a platform to make it easy to cut tiles etc. Most also feature water cooling / lubrication to control the dust and give a fine cut finish. Alas the one of these I own has far too little depth of cut to clean the face of a 4" wide brick, even if passing from both sides. Also this being in the midst of the COVID19 lockdown, tool shopping is not as easy as normal. So we need a quick hack solution that is effective and safe enough to leave all my fingers attached!

Design

To get the depth of cut required (over 2"), it meant using a 9" grinder, and a suitable smooth rim masonry disc. That then needed mounting securely in a table of some sort. So the first problem was how to get a good grip on the grinder. At first I looked at making a set of timber brackets that could clamp round the body and tighten onto it. The main problem here is that there not much clearance between the disc and the body of the machine near where you would want to grip it. This would not leave much space for any timber thickness, and that is a bit worrying with a 2kW machine spinning a large metal disc! So after a bit of hunting around I found a short length (about 5") of 3mm thick 40x40mm angle iron, and a 8" length of smaller 25mmx25mm angle. After hacking those about, drilling some holes, and welding them together we get:

AGSawBracket1.jpg

That is designed to allow the existing grinder side handle to pass through the bracket and screw into the rear mounting point (note that not all grinders have a rear mounting hole for the handle). The smaller bits of were then be drilled and mounted to a timber block with screws. This in turn fitted to the table (a scrap of 12mm MDF). Extra bracing was then the fitted to stiffen the table and form a second fixing to the block holding the grinder.

AGSawTable.jpg

The table surface was slotted by raising the blade on a (proper woodworking) table saw though it! Thus the grinder can be bolted in:

AGSawGrinderBoltedIn.jpg

Next we need a way of locking the motor on (it can be switched at the plug instead). A cable tie sorts that. Consideration should be given to fitting an emergency stop for added safety, especially if the power socket to be used is not readily accessible. (in my particular case I was running the grinder from a short extension lead, so the plug was readily available)

AGSawTriggerLock.jpg

I also added a hole in the table side to allow it to be clamped in a Workmate:

AGSawSideClamp.jpg

Finishing

To make the surfaces a bit more water and wear repellant, I painted some SBR sealer all over the table.

Testing

Now for the first test. Since it was raining, I tried this inside the workshop with dust hoses positioned to capture as much dust as possible - however you would not want to do much cutting inside!

In use it works surprisingly well, cutting fast and clean.

AGSawTestRun.jpg

Doing one side, flipping the brick and then the other gave a nice finish (click for larger images):

AGSawBrickFace.jpg

I added a slight mod to drill a 1/2" hole through the table at the very leading edge of the disc, to allow more dust to be ejected down through the table.

In Use

Prior to real use, I added a dust pipe to the output (this was just an off-cut of boiler flue pipe, with a slot cut in it with an angle grinder, and stuck to the underside of the table with hot melt glue):

  • AGSawWithAddedDustPipe.jpg

After about an hour of brick chopping, I have a nice pile of bricks, no edge left on that diamond disc, and a neat pile of dust:

See also