How to cut desktop CP "angles"

[Mattiekrome]

I tried to do some work on my desktop CP this weekend.  It went great until I tried to cut the angles involved with getting the CP top to sit flush on the front + back supports of the CP.  It took me nearly 10 minutes to explain to my friend at work the problem I was facing, so I drew a quick pic in paint.  Apparently the degree of angle is dependant on the distance between the front and back peices of the CP.  I jumped right in, cut the front and back at a 15 degree angle and was sadly surprised when it came out way wrong.  I then tried to cut the sides of my CP to the same height, hoping to "mask" any inconsistancies, but that didn't come out as planned either.  I sat here and tried to think of a logical way to go about cutting these angles, but just cant come up with anything "easy".  I'm sure this is a fairly common cut, so I'm hoping that I'm making it tougher than it needs to be.  Some of you experienced in the art of woodworking, care to lend Any help + advice?  Thx!

I am currently looking at FIG A, hoping to turn it into FIG B.

[Games001]

If the CP top is a straight line from top to bottom, then the angle of each frame side (front and back) should be the same *.  If not, you get an angle tool from Home Depot for $3.00 and confirm each one.

Once that is done, it's just a bit of cutting with a circular or jig saw at an angle.  Many, not the cheapo ones, of these tools have built in 45* (or more variations) angle locks to move the cutting guide into a close to perfect angled cut.

[shardian]

Have the top piece overhang on all sides, that way it does not have to be angled. That is how the CP is done on a lusid design, or the project arcade design. The only angle you have to worry about is the slope of the cp, and cutting the base to match that slope.

And to answer your question, the "angle" is not dependent on distance. The distance between the front and back IS dependent on your slope though in reference to the width of the CP top.15 degrees is a pretty steep slope. Use 7-10. The trig functions on your calculator are your friends here.

Pick a slope, say 10 degrees. Having that and the width of your control panel top, the hypotenuse, you can calculate the dimensions of your side panels - with reference to a pre-determined minimum height at the front of course. Once you have sized your side panels, you can then rip the front and back panels using the appropriate degree setting on your saw.

[Jdurg]

Also, if you come up a bit short, don't ever underestimate the usefulness and greatness of a hand planer.  It saved my butt numerous times!

[shardian]

Also, if you come up a bit short, don't ever underestimate the usefulness and greatness of a hand planer.  It saved my butt numerous times!

I need to get one of those. I have that problem alot.

[sstorkel]

This one seems pretty obvious... If you've got Figure A, you just need to cut a bevel on the ends of the left and right pieces so that you end up with Figure B. Bevel cuts with a circular saw are tricky, though. you'll probably want a saw board and a protractor of some sort. Don't trust the degree markings on your circular saw, if it has them! Measure everything with the protractor, preferrably a good protractor (e.g. the kind a machinist would use, not the cheap plastic ones you get at an art supply store).

[javeryh]

Can't you just use a little geometry to find out what the angle should be and then rip the piece at the table saw?

[NickG]

If you cut your left and right sides first, you can just align your circular saw angle-cut to them for the bevel cut on the front and back piece.  You can make this angled cut on a single board (wide enough for the back piece and twice as long), which you can then cut your front and back pieces from.  Then you can straight cut each piece to adjust their heights flush with the sides - or inset; depends on what style you are after.

[Mattiekrome]

Thanks for all the input, seems like a fairly simple cut, but Its caused me to decide that I will scrap everything that I had previously done and start again from scratch. 

The CP top is going to hang over the left side, right side, and back edge by 3/4", while the bottom will have a bit more of a hangoff for palm + wrist rests. 

I think I'll heed the advice and go with a 7 - 10 degree slope, and also do like NickG suggested and cut one longer beveled peice of wood, then cut the front and back out of that peice.  At least I'm certain both bevels will be the same angle that way, not to mention it is WAY easier for me to do a straight cut, than trying to do a precise beveled cut. 

[G1zm0]

for different angle cuts i used a circular saw and a jigsaw set at 45 degs or what ever depending  on angle u want a
then a little sand to tidy it up

[scotthh]

Someone slept through Trigonometry in high school .  "The tangent of an angle is the ratio of the length of the opposite side to the length of the adjacent side." That's A/B in my amended version of your Fig. B. If you have those lengths measured, you (or someone here) can calculate the angle.

[IA1NY]

Someone slept through Trigonometry in high school .  "The tangent of an angle is the ratio of the length of the opposite side to the length of the adjacent side." That's A/B in my amended version of your Fig. B. If you have those lengths measured, you (or someone here) can calculate the angle.

It's even easier than that. (Some of us don't math so well)    Lay out a section of the CP (like your picture is) but in full scale.  I usually use a scrap for that.  Then you can measure directly and make sure your parts fit, and adjust accordingly. 

[um3k]

I think you're overthinking this.  On the original Lusid plans, they just have you cut the back down to a 45 degree angle, basically anything equal to or greater than the slope of the CP is fine.  On the front you don't have to trim anything - a regular 90 degree angle is fine.   Doing it this way makes the CP top rest on the front edge of the front of the CP box, the back edge of the back of the CP box, and squarely on the sloped sides of the box.

Since the sides of the CP box are fitted OVER the front/back, hiding them, the corners are not visible when looking from the side.  So when you look at it with the CP top on from the front you just see the front edge meeting the CP top, and looking from the left or right, you just see the CP side, which hides the corners anyway. The only time you would see that the front and back are not exactly flush with the top, is if you have the top off and are looking at it from the inside, and I can live with that.

I modified the diagram to try to show what I mean.  If my attempt at the description and sweet mspaint skills don't get the idea across, I can take some photos of my CP to show what I mean.

[shardian]

I think you're overthinking this.  On the original Lusid plans, they just have you cut the back down to a 45 degree angle, basically anything equal to or greater than the slope of the CP is fine.  On the front you don't have to trim anything - a regular 90 degree angle is fine.   Doing it this way makes the CP top rest on the front edge of the front of the CP box, the back edge of the back of the CP box, and squarely on the sloped sides of the box.

Since the sides of the CP box are fitted OVER the front/back, hiding them, the corners are not visible when looking from the side.  So when you look at it with the CP top on from the front you just see the front edge meeting the CP top, and looking from the left or right, you just see the CP side, which hides the corners anyway. The only time you would see that the front and back are not exactly flush with the top, is if you have the top off and are looking at it from the inside, and I can live with that.

I modified the diagram to try to show what I mean.  If my attempt at the description and sweet mspaint skills don't get the idea across, I can take some photos of my CP to show what I mean.

Brilliant!