How to attach a mortar rake to an angle grinder


(Patrick Bell) #1

In preparation for repointing an outside wall I followed a neighbours advice and got hold of a couple of mortar rake bits to "use with an angle grinder" he had said. He has finished his walls to perfection but he's now vanished back to the UK. My angle grinder appears to have a 5/8" shank and I can only find 3/8" or 1/2" chucks. I need to be able to use the angle grinder to stand up to the sideways torque raking the mortar may require. the best that Ebay comes up with are 5/8 to 3/8 microphone stand adapters which look like a much finer thread.


Any advice?


(David GAY) #2

Yes Patrick un enduit can cover a multitude of sins. If it's been made with sand and chaux then the wall will continue to "breathe" and damp shouldn't be a problem. Sometimes the enduit gets enthusiastically painted with a cementitious paint like Snowcem in which case its ability to breathe will be reduced.You can get ready to mix products manufactured by companies like Weber and Broutin which are chaux based and of very high quality these have the advantage that you don't get variations of colour from mix to mix and are available in a range of tones. Were you to decide to replace the existing render I'd concentrate on hacking the old off and leave it to a pro to put the new stuff on. They make it look so easy and they're so quick!


(Patrick Bell) #3

Mine isn't like that which is why I want to repoint correctly. However it makes me wonder about the front of the house which is covered in crepi - I'm told because the mix of stone and brick used is a bit random and looked ugly. What does crepi do to the damp releasing qualities? Not that I want to remove it but it is painted and no lime afaics


(David GAY) #4

You can always tell an Anglo house. Horrible grey pointing inside and out. Why don't they look at magazines like Fine House Building. American it may be but lots of info about old techniques.


(Bernadette Kirk) #5

Agree with David. OH uses a chisel bit on the hammer drill and the result using lime and sand is perfect. Just remember to make sure the sand is the right colour, bright yellow pointing does not look great.

Our Marie spent an absolute fortune having their pointing done last year. The builders used cement in the mix and it is blowing the stone out already.


(Patrick Bell) #6

Yes exactly. The previous owner has patched with grey cement too. I plan to remove it all (grey cement that is) and yes chaux de saint astier indeed.


(David GAY) #7

Please don't use cement. Yes it does make the jointing mixture harder but it also makes it unconducive to letting rubble walls breathe. And please don't use grey cement which is just plain ugly but this does not seem to deter the Brits from using it. Just use a sharpish sand and lime preferably "Chaux de Saint Astier"


(Patrick Bell) #8

I was actually following advice from my neighbour who was repointing his outside walls and the result seemed good. However the mix he was using from the local builders yard seems to include concrete in the mix (which several people french and english have talked about being done to 'toughen' the mortar) but my inderstanding is that concrete in lime mortar mix totally messes up the permeability of the mortar and prevents the damp from 'escaping'. iow perhaps I needed to supplement his advice as you have done thanks very much.


(David GAY) #9

Ah well there you have it Patrick. If it's a stone wall unless it's very posh and made of "ashlar" blocks laid in courses then there aren't any layers of mortar to rip out. In fact in UK this is a popular con by our travelling freinds when it comes to brickwork, particularly chimneys "Oh dear your pointing's perished" let's rip it out and splodge some mortar in the cracks. Total waste of time. If your house is the usual sort of rubble made to course the most you need to do is pick out the soft bits , give it a good soaking and then go for 'pierre apparente" which means you overfill the joints and stones and then brush off to create a nice monolithic c wall appearance.


(Patrick Bell) #10

I see now, I was starting from the wrong point - I'd bought the wrong mortar rake bits. Its pretty soft lime mortar that will probably mostly come out with a chisel anyway. Not sure about the guide box since its a stone wall.


(David GAY) #11

It seems to me Patrick that beside the bits you also need the guide box which usually comes with a dust extractor connector to attach a vacuum cleaner. Also angle grinders don't come with chucks but with a threaded spindle and two collets. You can get an adaptor which screws on to the A/G spindle and then the mortar bit screws into the adaptor. The whole thing is then shrouded in the guide box which both limits the spread of dust and protects the user from flying debris and ensures you don't stray from the joint into the brick. Suggest you Google images "mortar rake angle grinder" there's another version which uses a diamond disc which is much more like a regular angle grinder application but still needs an appropriate guide box. Without the latter you could be carving some pretty patterns in your brick work. You can also get mortar rake chisels for an SDS Hammer/drill which you use on the hammer function; they act like a conventional hammer and chisel.