Anyone any good at maths?

[The Bear]

Folks
I’m building a cupboard to go against the slopes ceiling in my chalet bungalow. 18mm material. I have settled on some dimensions but can’t work out the knock on sizes. Drawing is a cross section from front to back. Angles are 45 degrees. Can anyone tell me what the distances are A-D and C-F please?

Mark

 

[The Bear]

.

 

[The Bear]

Um
Numbers are hard to read on my computer
The 4 key measurements on the drawing starting at the top are
196mm
178mm
1150mm
788mm
If that helps

Mark

 

[John15]

Not much good at maths but how about drawing it out full size on a sheet of ply.

John

 

[lurker]

Can you be sure your walls and ceilings are flat, level and square?
I tend to build frames against walls as I go along, as I am yet to come across square corners in buildings.

 

[The Bear]

John
Already drawn full size on paper but can’t be sure of the accuracy of my angles and therefore measurements. I’m not cutting the sheets hence I need an accurate number to give

Lurker it’s not intended to follow the contours or the building.

Mark

 

[Inspector]

25.4558mm is what I get. Square root of (18 squared times two).

I don't understand what good it does you since you need the length of B to C to cut the sheet goods that fits between the top and front and when you cut it the other dimensions take care of themselves?

Pete

 

[Steve Maskery]

I recommend that you don't mark out from measurements, mark out from marks. Make a rod, full-size drawing on a piece of thin MDF. You can check that the rod fits and then take all your setting directly off the rod, without measuring anything. It is a boon for this kind of work, where a tiny mistake in an angle can throw out something else quite widely.

 

[The Bear]

Steve I understand the benefits of a rod. But I’m not cutting this. There are 2 of these to make. The panels are being done on a professional panel saw I’m told is 0.1mm accurate. So I have to give them measurements

Inspector Pete. I don’t want to sound dismissive when I’ve asked for help but I’m pretty sure neither measurement I need is 25.4mm. I think you have provided A-B

Thanks for the help so far

Mark

 

[LancsRick]

A-D is 1132.9mm

C-F is 985.2mm

 

[Trevanion]

A-D is 1132.9mm

C-F is 985.2mm

:lol:

 

[thick_mike]

Hmmm, I get A-D = 847.8mm and C-F = 540.0mm

 

[Deadeye]

Hi

You're starting drawing is wrong I'm afraid.
The two top measurements (196 and 178) are not 18mm apart if the AD board is at 45o.
If you tell me which of the two is accurate, I can tell you the others.

 

[thick_mike]

Damn...true dat!

 

[Inspector]

Inspector Pete. I don’t want to sound dismissive when I’ve asked for help but I’m pretty sure neither measurement I need is 25.4mm. I think you have provided A-B

Thanks for the help so far

Mark

(homer) Ops! (homer)
Pete

 

[The Bear]

Ah I can see that problem now. I can keep either figure and adjust the other to suit. Thick mike which did you use?

 

[LancsRick]

Calculator was in bloody radians!

A-D 847.8mm

C-F 576mm

 

[thick_mike]

Ah I can see that problem now. I can keep either figure and adjust the other to suit. Thick mike which did you use?

196mm

 

[The Bear]

Ok. So I’ll go with 196 being correct. Forget the 178
Do we have a consensus with (the not so) thick mike then ?

Cheers all. I knew it was complicated

Mark

 

[LancsRick]

Why the lack of love for 196 and 178? If that is the short and long edge of the top horizontal piece then that is correct.