Door frame jig?

[Pete]

I am making my own door casings out of MR MDF as I cannot source my frames due to different widths. SO I am going to use 18mm for the frame with a 12mm plant on to form rebate. I am having shadow gaps around the door casings so no architrave. Has anybody made themselves a jig as I have 15 door casings to put in? I an thinking something along the lines of a 4 x 2 rectangular frame  made to smallest door measurement and properly square. I can attach my door casing to the outside (screwed  through the rectangular frame  into the MDF)and then place in the opening and pack accordingly. If I drill some elongated holes in the 4 x 2 frame where I would fix the casing I can then fix the casing permanently, remove the screws I attached the casing to the rectangular frame and Bob's ur titfer. Has anybody done this as it must be quicker than doing each casing the traditional way? TIA

[Onoff]

I did debate making my own doors. Still might. 

 

I made a hinge jig...

 

 

[Russell griffiths]

I used a door as a jig on my last place

placed between the jambs with packers, then screwed to the door

lift the whole lot in place, and fix, when all screwed in remove the door and put it into the next frame. 

Is that what you mean. 

[Simplysimon]

mdf is quite a soft material for standards, both for damage as well as for haning door from. suppose it may work though wouldn't do it myself. faced ply would be acceptable. how wide are the walls?

[ProDave]

I used engineered Oak floor boards for my door frames.

 

The only "tool" I used (apart from the usual spirit level etc) was a spare stick of wood cut to 6mm longer than the door was wide, to set the gap as you fix the door frame into place.

[Pete]

1 hour ago, Russell griffiths said:

I used a door as a jig on my last place

placed between the jambs with packers, then screwed to the door

lift the whole lot in place, and fix, when all screwed in remove the door and put it into the next frame. 

Is that what you mean. 

Sounds like it. Only problem is I do not have the doors yet so will make a frame as a substitute door

Edited June 4, 2019 by Pete
Forgot to addsomething

[Pete]

1 hour ago, Simplysimon said:

mdf is quite a soft material for standards, both for damage as well as for haning door from. suppose it may work though wouldn't do it myself. faced ply would be acceptable. how wide are the walls?

MDF is used all the time for skirting and door cases. 

[Hobbiniho]

18mm mdf, even moisture resistant is quite flimsy, what width does your jambs need to be? i usually used 115/145/195x 21 redwood cut and planed to size for door jambs as it is quite sturdy but even then they needed to be well packed an secured, i also would not be making up frames without the doors as it is quite difficult to get it packed exactly right, its also easier to pack with the door in place.

 

i would be interested to see how you hope to achieve your shadow gap, you also say you are going to create a rebate using 12mm mdf but there is no facings to cover the join between the 18mm and 12mm mdf? are you hoping to use filler to cover this join?

 

1 hour ago, Pete said:

MDF is used all the time for skirting and door cases. 

 

correct i have howdens oak veneer mdf door jambs but they are 30mm thick so not nearly as flimsy

[Russell griffiths]

You can get a plasterboard bead to create the shadow gap. 

[Pete]

9 hours ago, Hobbiniho said:

18mm mdf, even moisture resistant is quite flimsy, what width does your jambs need to be? i usually used 115/145/195x 21 redwood cut and planed to size for door jambs as it is quite sturdy but even then they needed to be well packed an secured, i also would not be making up frames without the doors as it is quite difficult to get it packed exactly right, its also easier to pack with the door in place.

 

i would be interested to see how you hope to achieve your shadow gap, you also say you are going to create a rebate using 12mm mdf but there is no facings to cover the join between the 18mm and 12mm mdf? are you hoping to use filler to cover this join?

 

 

correct i have howdens oak veneer mdf door jambs but they are 30mm thick so not nearly as flimsy

As @Russell griffiths says you can get shadow gap trims which is what I am using. The way I am suggesting is the same as using a door but a using a 4 x 2 frame instead. I will glue the the 12mm MDF in place and use a filler if necessary, once it has had a few coats of Zinseer it will be ok.