Help Me Draw A Dome [TUTORIAL]

D0me

Thanks Gaieus

D0me

Hi Guys

It seems like such a long time since last posting here.
Actually feels like something is missing from my daily routine.
I trust all are well.

I need some assistance.
I need to calculate the surface area and volume of my dome as it stands right now.
The reason for this is I need to know how much of cement I require to build this dome and the only way for me to know this is if I know the surface area of my dome. Also guys, don't forget to take into consideration the opening in my dome.

Do you'll by any chance have a formula for this and can you'll assist me with doing the dome size as it is in this thread as an example so when I redo this whole exercise, I can follow the example.

Thanks
Regards
D0me

pilou

Volume calculator by TIG?

TIG

I checked an earlier version of your dome - Volume ['by Integration'] ~= 0.227 cu.m [@~1% accuracy]
that's the whole thing - both inner+outer [with entrance]...
You can easily make a copy and group the parts you want - explode all together and then run 'Volume'...

D0me

Hi Pilou
Thanks for pointing out the Volume Calculator. Never new this existed but then again never new Sketchup existed and after finding it, I never new its power until my mentor, Gaieus tutored me.

TIG thanks for the calculations.
I am busy downloading the plug-in and hopefully find my way around installing it.

@unknownuser said:

Volume ['by Integration'] ~= 0.227 cu.m [@~1% accuracy]
that's the whole thing - both inner+outer [with entrance]...

Sorry if some of my questions seem silly but my knowledge on these calculations is really limited to say the least.

I will tell my supplier that the cement I require should be enough to cover an area of 0.227 Cu.m (Cubic Meter's, "Am I right"). Is there any other way I can explain to them the area that needs to be covered as sometimes its surprises that these guys sell products that they know nothing about so the more detail I give them, the better.
What does [@~1% accuracy] mean?
Lastly you mentioned this is the volume of both the inner and the outer incl the entrance. If we look at the file found here the inner dome is shaded in green and the outer dome is shaded in red. The inner dome is 3" and the outer is 4". Is it possible to get the surface are of each piece individually as the 2 domes (Green and Red) are separate material all together.

Thanks

TIG

I have redone it for you - since the shapes weren't 'manifold' I've fixed them...
The figures are in cubic meters - not an area.
You'll probably buy cement [concrete] by volume if it's bagged [you need to buy it in 'steps' anyway - so pick the next size up] - if it's to buy by weight then get an estimate of the equivalent volume from the supplier...
The '1%' accuracy is how accurately you let it calculate - the more accurate it is the longer it takes to do - 1% is the size of a walnut and you'll spill more than that pouring it into the molds
The green/yellow dome is ~0.067 cubic meters, the red one is ~0.159 cu.m and the white entrance 'arch' is ~0.11 cu.m...
[assuming you made it to scale = 1:1 and the parts intersect properly ???]
Learning--Fixed--Latest.skp

D0me

@tig said:

I have redone it for you - since the shapes weren't 'manifold' I've fixed them...
The figures are in cubic meters - not an area.
You'll probably buy cement [concrete] by volume if it's bagged [you need to buy it in 'steps' anyway - so pick the next size up] - if it's to buy by weight then get an estimate of the equivalent volume from the supplier...
The '1%' accuracy is how accurately you let it calculate - the more accurate it is the longer it takes to do - 1% is the size of a walnut and you'll spill more than that pouring it into the molds
The green/yellow dome is ~0.067 cubic meters, the red one is ~0.159 cu.m and the white entrance 'arch' is ~0.11 cu.m...
[assuming you made it to scale = 1:1 and the parts intersect properly ???]
[attachment=1:3cp7me2g]Learning--Fixed--Latest.skp[/attachment:3cp7me2g][attachment=0:3cp7me2g]Learning--Fixed--Latest.png[/attachment:3cp7me2g]

Tig: thanks for working this out. Now I can attempt working out the volume myself and I can use your numbers as my guideline. Once I can accurately find my way around this neat plug-in, I can then confidently do this when I redo my dome in a different size.

With regards to the accuracy, I'm guessing the higher I make this, the more room I allow myself for wastage. This being my first ever such project, I will have to increase this number as I can anticipate wastage due to my inexperience.

As for the model being on a 1:1 scale, I think it is so, as all the dimensions I'm going to use on my real model will be exactly the same as the sketch. Gaieus can confirm this for us though.

Lastly, the arch. The volume of the arch is not the whole arch piece as you have it displayed but rather the protruding part of the arch that sits right at the mouth of the dome which I think is +-2" (Sorry, I'm replying from my mobile so don't remember what thickness this was). I'm sure this can be sorted out quite easily.

Thanks a mil for all the help.
Regards
D0me

chrisglasier

DOme, I am beginning to think you are really some kind of maniac.

You refer to cement when you mean concrete. A common mix of concrete is 1:2:4 - one part cement to two of sand to four of aggregate (stones). Refractory cement is rapid hardening which means you will have little time to play with the mix. If the aggregate is not equally refactory it will explode with temperatures over 200c degs or so that your oven will produce. You will be working with materials that you are unfamiliar with on a double curved structure that essentially will need to be built up in layers - like plastering.

Please get hold of some clay from the puddles on construction sites and some sand and make a proper start - otherwise you will be disappointed and out of pocket.

Chris

D0me

@unknownuser said:

DOme, I am beginning to think you are really some kind of maniac.

Ouch!!! "Maniac", that makes me sound crazy. I would rephrase that to a more appropriate word like, "Determined".
I know what you getting at Chris. You feel that for a start, I should work with materials that are cheap and would result in less damage to my pocket and my project.

Never the less, I did do a considerable amount of research here and feel that I am truly ready to use refractory Cement. I admit that sometimes I use the wrong terminologies when referring to certain materials, but I do know the difference between the two and will try not to mix them up in future.

I really appreciate your concern and will keep the safety tips in mind like rapid hardening of refractory cement and exploding of concrete.

Thanks
Regards
D0me

D0me

Hi Gaieus
I trust you are well.

Seems like a long time since posting here. Actually missing all the challenges I had in creating this dome but let’s see what the future of this project holds.

I’ve been doing a bit more thinking (Never really stopped) and I can safely say that these are the new dimensions of my oven. By following through this tutorial, I will be able to do this without much heartache but there are a few more additions and possible subtractions to the current design.

I will list them below if it is OK.

The cooking floor size will be 15 Inch radius
The dome size will be 12 Inch radius. The dome will sit on the floor and will be 13 Inches high. The dome will be 3 Inches thick and will be a neat fit to the edges of the floor. Below this dome will be another dome that is 1” thick and below this 1" thick dome will be another dome which is my Sand Dome and my main guideline for building the final dome. There is no real thickness to the Sand Dome as it will cover all of the area below it.
In the center of the dome will be a round pole with a radius of 2 Inches as suggested by Chris. The dome will sit against this pole creating a bevel at the top.
The dome will be divided into 4 equal pieces.

That’s all that I can think of that has changed from the previous design. I should be able to proceed with steps 2 and 4 comfortably.

Step 1 is a little complex for me as the floor will consist of bricks and these bricks come cut into a size of more or less 230mm(length) X 114mm(Breadth) X 76mm(height). I am still sourcing out these bricks but this I believe is the standard size unless I find someone who has a different size. Is it possible to sketch these bricks over the concrete slab from the center of the slab going in a Herringbone pattern and eventually ending up with a radius of 15 inches. Also will it be possible to tell me how many bricks I would require and how many bricks would have to be cut to specific sizes to achieve this pattern.

As for step 3, please can you assist me there as well.

I hope all this makes sense but if there’s any further explanation, please let me know.
We don’t have to start with this right away but I thought I’d pass the plans through you so any preliminary planning can be done and we can answer anything that needs to be questioned.

Look forward to hearing from you
Regards
D0me

chrisglasier

DOme, you have had a good run with Gaieus and some extra-SU suggestions from me and others. You can answer the questions you raise yourself now. Tell me, for example, why you want to lay the bricks diagonally. Whatever, draw them and count them, 1,2 ...

Gaieus

Hi D0me,

Regarding Step 1 and the fishbone pattern bricks (aka "opus piccatum" or "~ spiccatum" in Latin ), please have a look at this post (another dome topic actually you can even go through the whole topic to collect other ideas, too) if that solution would fit your needs.

As for step 3 - you can always build a cylinder with a radius of 2" and intersect the dome parts with that cylinder (just like we did with our entrance).

Now as you are thinking of only 4 segments, maybe even the entrance could be put into a single segment instead of cutting two. Needs to be carefully thought as the sides may become too thin and week to hold the dome but at least you could make a variation of the design like that.

D0me

Hi Gaieus

Thanks for the response. I will go through the link you gave me and follow through to make the pattern I require for the floor

With regards to the Dome, I will follow through the tutorial from the beginning of this thread.

I will start by first creating the cylindrical 2" pole in the center of my first circle and then start drawing the domes around it. Will that be the correct way to start or should I first do the domes and then fit the pole in and then intersect?

With regards to the entrance, I will play around with putting it into a single segment and see how far I get. I will update my progress here and if its OK, request assistance when need be.

A quick question. Since this dome will now be divided into 4 pieces, what should the segment count be. I know that we originally made it 24.

Thanks
Regards
D0me

Gaieus

@d0me said:

...I will start by first creating the cylindrical 2" pole in the center of my first circle and then start drawing the domes around it. Will that be the correct way to start or should I first do the domes and then fit the pole in and then intersect?

You can do it either way - start with a shape that would lathe around with the hole in it or intersect later. Doesn't really matter actually.

@unknownuser said:

With regards to the entrance, I will play around with putting it into a single segment and see how far I get. I will update my progress here and if its OK, request assistance when need be.

Sure - just coma back with any questions any time.

@unknownuser said:

A quick question. Since this dome will now be divided into 4 pieces, what should the segment count be. I know that we originally made it 24.

We changed the 24 segment circle to 48 and indeed the 12 segment arc to 24 (i.e. doubled both). This can still be the practice as both are divisible with 4, too (and that is the main point)

D0me

Hi Gaieus

I've started redoing this exercise but didn't get too far.

I came up to this point and then couldn't get further.

I noticed in the link mentioned above, you said that the ideal solution was somewhere between yours and mine. I downloaded the version you uploaded there and tried looking at it to see if I can find my way around. I noticed that both arcs in your version were made into individual groups using the same circle. My guess is that 2 circles were created with the same radius.

I also noticed that the ARC's in my sketch (attached)are not as smooth as the ones you created found in the link above (Edit: After posting, I rechecked my sketch and realized that i forgot to set my segments for the arcs to 24. After doing so, it looks much more smoother and rounder. I have attached the sketch with the new line segments on the arc. You will also notice that I have added additional arcs on this new sketch. My sketch will have a total of 5 domes piled onto each other as can be seen in the sketch.)

Thanks
Regards
D0me

Dome X 3.skp

Dome X 3 - Additional Arcs.skp

Gaieus

You need to select a face and a path (two half circles) and group them. See image. Do this with every, individual face + half circles (there are a whole bunch of them - you can include a pair in each group - see my attached file where this is already done).

Dome X 3 - Additional Arcs.skp

D0me

Hi Gaieus

I've been trying to do that since yesterday but instead of clicking once on the semi-circle, I ended up double clicking, which is probably the reason I was unable to group it.

I have managed to group the arcs with the 2 semi-circles but I did notice a slight difference between your model and mine.

I have attached images explaining the difference.

The first image is my model and the 2nd image is yours.

Should I be concerned about what I noticed.

My--Sketch Dome+Archs--Grouped.JPG
Gaieus--Sketch Dome+Archs--Grouped.JPG

Thanks
Regards
D0me

Dome X 3 - Additional Arcs.skp

Gaieus

It's because the original circles are still there and for some reason, SU prefers those to be displayed (greyed out) instead of the ones in the group. Hide all the groups, select all the remaining, loose geometry and delete. You won't need it anyway and it will only litter the model and confuse you later.

D0me

Hi Gaieus

Thanks, didn't even realize that there was some left over circles on the model.

Now I can proceed.
Will keep you updated on my progress and surely drop by with any issue I experience.

Take Care
Regards
D0me

Gaieus

Alright!

Looking forward to your advance with the model!