DIY Home Improvement Forum banner

suggested grinding wheel - repoint soft mortar

9505 Views 10 Replies 7 Participants Last post by  stadry
Need to repoint / tuck point many of the brick window sill joints, under aluminum frame windows.

Mortar is quite soft (skimped on portland on this house), but too many to drill / scrape by hand (my hands kill me).

Shouldn't a cheap "abrasive" grinding / cutoff wheel work fine on soft mortar - won't need a diamond wheel?
I think I can borrow a 4" angle grinder.

Without spending fortune on special tools, I'm not sure about mechanical way to remove mortar up against bricks?
Short, abrasive sawzall blade?
Or go slower w/ angle grinder when near the bricks? These are hollow bricks - holes on top & bottom - to get hung on with reciprocating tools.

Even my Dremel w/ abrasive blade (v. thin) would cut this mortar, but not 3/4 - or 1" deep.

Seems like I've always heard to remove 1/2" to 3/4" old mortar for repointing.

One site says, depth of 2 to 2-1/2 times the width of the joint?" But immediately follows:
"Often I see contractors bidding repointing projects calling for the depth of the removal at ¾ inch. For most mortar joints that are the thickness of your little finger, about 3/8 inch, this is not deep enough."

Well, 3/8 * 2 = 3/4". So...?
1 - 11 of 11 Posts
I have done that once with a 4-1/2" grinder. Makes a total dusty mess, but cuts through soft mortar very quickly. I found that if the mortar was decayed, the grinding wheel went right through it. Other places, the grinder had a hard time with the mortar, so I considered that mortar sound, and did not replace it.
A grinding wheel specified for concrete should be fine.
Thanks. Any thoughts on which works best - angled or straight grinders? Son said he had both (pneumatic) in smaller sizes.

Not sure about the mortar that touches the bricks.
Even if remove all but ~ 1/8" thick layer w/ a grinder, then hand scraping or chiseling the rest sounds like pain, to me.

After the bulk of joint is removed, maybe scrape 1/4" deep by hand - right next to the bricks, then continue w/ grinder - so not to hit brick face?
An electric angle grinder is so cheap at Harbor Freight, it makes no sense to rent. Pneumatic also cheap, but depending how high you have to go, that hose gets pretty heavy.
Posting a picture of what exactly your trying to do would be a big help.
Any cheap 4-1/2 right angle grinder will work.
A diamond wheel is not that expencive and is not going to wear down like a cheap abrasive wheel.
When you get down to 4 or 4-1/2" diamond blades, they get fairly cheap; plenty at Lowes that are under $15.
unless this is 'your work', tuck blades are your best choice impo,,, we don't diamond saw mortar

here's a source for our tools [ no $ interest ] - - they sell a rotating carbide bit incl us spindle size adapter - it sweeps the joint & has shroud w/vac attachment

fairly inexpensive imo - NO dust, either - guys work faster & turn out better work
  • Like
Reactions: 1
we use nilfisk hepa w/plastic garbage bags - they use about the same thing,,, euro dust standards are more stringent than us currently
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.