Thread: Plastering - Setting 135 degree internal corner.

Rod (our resident plaster expert) should be along to give you the best advice, but I wouldn't bother with one of those tools. I'd just use a straight knife to do one side first, then let it set before you do the other side. But that could pose problems if you're using paper tape (Rod doesn't like the easytape, but I'd just put a double layer on the corners )
I have used an internal corner tape that has metal strips embedded for reinforcement to keep it straight.

lol thanks Pawnhead

The best method is to get a 135 degree metal internal angle. The are very much like an enxternal but opposite. Often there is nothing to nail to in the internal so the best method of fixing them is staples. They can be a bit fiddely to get in the right position. If you find the metal is sticking out they can be closed up a little by laying them out on a flat surface and gently treading along them, get a couple of spares cause that takes a little practice.

Forget the adjustable internal tool they are hopeless I won't even try to use one.

To do it without metal angles there are several options however each has there benefits and pitfalls so I find the best way to get a perfect job even though it takes a little longer is this:

Pre fill any gaps and scrape back flat. Then use paper tape to reinforce the joint just like a normal internal. At this stage don't worry if its a bit wobbley. The most important thing is not to have any dry spots under the tape. (check out my video on internals on youtube [ame="http://www.youtube.com/watch?v=Jp5tiv-XYKc"]YouTube - Setting an internal angle with paper tape PART TWO[/ame] and [ame="http://www.youtube.com/watch?v=sJnKioL-Qng"]YouTube - Setting an internal angle with paper tape PART ONE[/ame] although these are standard internals the principle is the same.

Now take a chalk line and from top to bottom flick a line so that it takes out any wavy areas. You can either (if you have a good hand) cross trowel using the line to guide you to get a straight corner. Or the sure fire method is to temporary fix an egde to work to following the line and trowel down using the straight edge as a guide. Remove it and do the same on the other side.

I find using furring channel upside down the best straight edge as the leading edge of the "top hat" section is only thin and easy to work to.

I wont go into other methods here because they are also prone to giving you a wavy finish if you are inexperienced and you end up having to use the method descibed above anyway.

Hope this helps.

Cheers

Rod

Rods got the solution.
Well we worked on an old job with very old hard timber underneath
the walls were very crooked but as I was working with cabinet makers I used their air compressed staple gun and wow it was magic it went through even the metal internal bead and held very nicely onto the wall. The internal angle beads with holes in it are better than the mesh type ones. Rod can elaborate what I mean.
If they are available in your state.
I used staples before but if you hit the metal they will stick out too far and you cant get a good finish then. you have to get it just right.
John (pawnhead) also has a god idea if you cant get an internal angle bead apply the plaster then put on the paper tape and work in both sides as Rod video suggests. After the plaster has gone hard apply a second coat on only one side trying to make nice and straight. Let that go off then put on the other side.

Originally Posted by rod@plasterbrok

lol thanks Pawnhead

The best method is to get a 135 degree metal internal angle.

Better advice than mine, as always.

Here's a pic. Two nice straight metal edges to work to.

Yep that the one thanks Pawn.

BTW solutions put forward by me are not always practical for everyone or every purpose. Your contributions and anybody elses for that matter all have equal merit any provide valuable insight to readers to better understand the ways in which they can go about solving their particular problem.

My posts are from a trade back ground from 30 years in the industry, therefore at times are biased toward more trade oriented solutions where the person may or may not have the right tools and accumen to follow that advice.

Ingenuity in problem solving from others, that have been faced with the same problems also without the right tools etc, are sometimes more valuable information to the poster than mine.

In most cases there are often many ways to "skin a cat" putting forward as many options as possible is a good thing and should be encouraged. I am always on the look out for better ways other than my own to do things, and have myself utilized suggestions put forward by others on this site.

Keep the posts comming people.

I had some tricky internal angles where some fancy cornicing had to meet in a skillion area where the walls and roof were not square or plumb. I put up the two long sides with what I thought was the right angles cut in but could not get the shorter lengths right. When I got one end mitred right it would not lie flat against both wall and ceiling to meet at the correct angle at the other end.

I was running out of lengths anyway but wanted to at least get the corners set before going to bed - I ended up cutting 4 short lengths about 300 mm each and fooled around until each one was cut and able to be placed correctly in a corner. I then just infilled the missing bits the next morning (make sure the ends are cut square).

Not the way the pros would do it I'm sure but it worked and the minimal time needed to patch the joins was nowhere near the 2 -3 hours already wasted trying to do each side (and both corners) in one run.

When you are putting cornice up on a raking ceiling you cut the mitres exactly the same as a flat ceiling. The cornice is then put up on the ceiling as if it were flat, causing the cornice to have more fill on the bottom member.

In other words to get the mitres to match with the cornice lying flat against the wall is impossible! As it would require the cornice on the side to be horribly twisted to meet at the top as well.

Irrespective of how steep the rake is the cornice is cut with standard mitres put the sides up first at the correct projection then the top and bottoms to match the mitres.

Cheers

Rod

I remember the early days when my father used to scribe in cornices. I think all the boys from the old school knows all about this including rod he would have come acroos a fair bit of that in the early days.
Carpenters still scribe in their skirting. But yes doing it the hard way will only be a good thing as long as you get the end results and work on improving the next time around.
If you can imagine a flat trowel with all the handle cut off and just square metal. Cut a 45 on one corner when we were apprentices we used that to get in corner work like fnacy cornices or in our case picture rail mouldings. It can easily follow the pattern on the cornice. I think I will put in a picture to show what I mean

Rmartens, as a 2nd year apprentice I took on a weekend job (4 units), with cornice on a rake, I had no idea how to do it. On the first one I scribed the mitres then realized that the cornice was on the same plane as the ceiling regarless. It was there that I learnt that the mitres were cut the same. Never forgot that lesson.

What you are talking about is called a joint rule and you can still buy them in different sizes. I have one in my tool kit still. I find them very useful for certain jobs.