Designing my own desktop for a desk

masta_killa

Intro

Hi everyone,

I'm still new to OnShape and I only have a bit of experience with SketchUp (which I also didn't use anymore for some time already).

I probably won't understand you if you try to explain things with words, so if possible please show me with a short video or any other way you think might be more understandable.

I did already try finding a solution by searching on Youtube, but I couldn't find anything applicable or understandable for me (but probably I simply didn't use the correct search terms).

Thanks a lot for your understanding and support!

So I'm trying to design my own, my wifes and a friends future desktop, which we will CNC into the shape of our dreams and install on an adjustable desk frame.

I'm currently stuck on few problems...

My own desk

I'm already quite happy with the 2D shape (in yellow - done with many "conic" curves). The curves are smooth and shape is what I want it to be.

I also have no problem extruding this into a 16mm high 3D shape.

However, I would like the edge of the desktop to be rounded. I tried achieving this with the "fillet" tool, but it seems like this can only round a single corner (so a 90° part), while I'd like to round the whole edge (so a 180° part). I can round both corners, but to make the curve smooth (no straight lines) I then have to curve it with a diameter of the thickness of the desktop (16mm), which is waaaaay too rounded for this edge. If I use a diameter less than 16mm, only the corners are curved and not the whole edge. The curve has to be for the whole edge and quite soft (it may come out only about 3-4mm, so it should be a "circle-curve" with a diameter of of a lot more than 16mm). Not sure how to do that.

Below some screenshots showing what I mean:

My Wifes desktop

I'm not really happy with the 2D shape (in yellow) yet. My wife would like to integrate her arm support in the design of the desk. That is why there is this circle of 324mm cut out in the front / middle.

But the circle curve doesn't flow smoothly into the conic curve (see below) and I'm failing to fix this. I tried using other curves than conic too, but those are even harder for me to flow from curve to curve smoothly.

I'm also not really happy with the shape in general. Perhaps I can fix this later changing the rounding amount here and there, perhaps not. But I think I need to learn how properly integrate that circle in a smooth manner first...

After this, also the extruding into a 14mm high 3D shape should be easy.

However, the edge for this desktop will a bit more complicated... I'd like the edge to make it seem like it is a very thin desk. So the edge needs a shape more or less like below

The above 2D edge shape should follow the entire 2D desktop shape (except perhaps a section of the back, so that it still has enough strength for a monitor arm, but lets keep that part for later ). After searching for a very long time, I still failed to figure out how to do this...

Also, as you can see in the screenshot above (this is the left part of the edge zoomed in a lot), I'm failing to make the half-circle transfer smoothly into the conic curve. It has a small "corner" in it.

My friends desktop

Didn't start on this one yet, but I don't expect issues with the shape (rectangle with rounded corners) of the desktop itself.

The edge should be the same as my wifes desktop. So same problem for that.

Outro

I Hope was able to make myself a bit clear and I hope someone can help.

Thanks a lot in advance!!

Roberto_Verduci

Hi masta_killa,

YOUR DESK
it would be nice to have the original desk shape to try to make what you ask for, but it may be that in the example of your wife's desk the function I used could be right for you in this project too.

YOUR WIFE DESK
here you can find a document I shared. I used spline instead conic curve for the arm support shape and for the edge shape. The use of spline allows you to set trangent constraints at the beginning and at the end of the curve:
https://cad.onshape.com/documents/049648a82c4e6b1f3f2d6929/w/ea9d7e4aed8c0b8712094444/e/b06db3e168137a1ba564215d

I hope this could be useful.

masta_killa

Wow thanks a lot! I will study and try to understand what you did this weekend...

I just figured out how to share my documents with a link, like you did... So here they are

My desktop: https://cad.onshape.com/documents/c6b0d04bc102f3a914533702/w/44750f3e274a044e3d786c29/e/805d6bf6490b1fa1d08984f5

My wifes desktop: https://cad.onshape.com/documents/5be4070c9cb0c335259b9edb/w/b0184c0361df73e14eb81a2b/e/985ae6ac6068408f2caacb29

robert_stiles

Hello, 

Looks like @Roberto_Verduci 's approach is exactly what I would try first, but if it helps at all, I thought I might chime in with a non Onshape comment... Its going to be expensive to CNC machine a custom underside. If cost is an issue, I might find what coving tools your machinist has in stock, so they can just run it all the way around. 

Your profile can be done, but it will be more expensive than running around the edge with a tool, or set of tools they already have, and will likely need lots of sanding after machining. 

Good luck

nick_papageorge073

I didn't read the whole thing....

For "My own desk": you need to use the "sweep" tool to get the radius you desire.

masta_killa

I'm now trying to understand the drawing from Roberto_Verduci, but I'm having some trouble figuring out which tool he used for certain curves.

For example, below curve I can identify as a spline, because there is the option to "insert spline points"

But below curve doesn't have this option (so I guess it isn't a spline?). It seems exactly like a part of a circle, but it also doesn't have the option to edit the radius anywhere (so I guess it then also isn't a circle?). How does this work? How to I identify what tool was used to draw something? There must be an easier way for this, no?

edit: 

Aha... I found the radius for the "circle" above... I looked over it because it is actually outside the circle-part itself...

Also when trying to recreate the spline myself in my drawing, it didn't work well when I tried with spline. However it was easy when I used a bezier curve (which I guess is a type of spline).

So one more reason that I would find it very useful to be able to identify which tool was used for drawing something...

masta_killa

robert_stiles said:

Hello, 

Looks like @Roberto_Verduci 's approach is exactly what I would try first, but if it helps at all, I thought I might chime in with a non Onshape comment... Its going to be expensive to CNC machine a custom underside. If cost is an issue, I might find what coving tools your machinist has in stock, so they can just run it all the way around. 

Your profile can be done, but it will be more expensive than running around the edge with a tool, or set of tools they already have, and will likely need lots of sanding after machining. 

Good luck

Thanks for the advice! With the "custom underside", do you mean the "edge that seems thin because it slowly migrates from thin to thick"? Or which aspect do you mean exactly?

The material of the desktop is HPL (for my desktop it also contains 2 thin layers of aluminium sandwiched  inside the HPL). I'm no expert on this to be honest (my friend is though, he sells these plates), but from what I was told, this is an extremely tough wood-based material, that is best CNCed into shape. Traditional coving tools might not work well on it? Again, I'm no expert on this, so maybe I misunderstood something...

Cost is not the most important (else I'd just go to Ikea or something ), but my budget is certainly not unlimited either. I have no clue tbh how much the CNC might cost. I wanted to send them a design and ask for a price and if it is ridiculous, then I'll probably make some adjustments

dirk_van_der_vaart

He used the spline tool

masta_killa

Ok, so I guess I more or less figured out now how to properly do the curves using the bezier tool...

And I'm also getting pretty close to figuring out the sweep tool... But it is still acting a bit weird...

The sweep works for 6 out of 10 of my curved lines that I use as sweep path. But 4 out of 10 do not work (1 even works sometimes which is totally weird). Can somebody perhaps look in my shared document (my wifes desktop) and tell me what I'm doing wrong? Thanks!

Here are some screenshots:

And below a screenshot where I select the exact same line as in the second screenshot, but then it does work. I did unselect another line first to achieve this, but sometimes it even works without unselecting another line.

It almost seems like it is running into some limit or something...  (not my memory, I have 24GB of RAM free)

edit: I just tried the sweep on my desktop and I have exactly the same problem there

masta_killa

I noticed that it says "insert control points" instead of "insert spline points" when using bezier. So I guess you're right... But is there an easy way to figure this out? (besides deriving it from which menu options are shown)

Roberto_Verduci

Hi,

I'll start by saying that I don't know the problem technically, but the sweep process in the two straight sections is solved by moving the curve of the edge drawn in the sketch away from the projection of the straight edge. Most likely, leaving the tangency generates a face error and this causes the entire process to fail.

I edited your original 2 mm quote to 2.1 mm



and this is the result:



As far as the circle part is concerned, you get an error because the sweep self-intersects. 



So either you change the depth of the profile (the original quote of 75 mm) in order to eliminate the problem or, as I did in the document I published, first do the sweep on the desk without the circle and then add the circle machining.

masta_killa

Thanks again Roberto!

I now have managed to complete a first draft of my desktop with everything in it!! (I still have to look into those "sweep self-intersects" for my wifes desktop)

I wanted to send this draft of my desktop to the company that does the CNC and ask if this is possible for them to make and how much it would more or less cost. They told me to send them a DWG or DXF file, but I'm not succeeding in exporting the 3D model as DWG or DXF. Only when I right click something 2D, like a sketch, I get the option to export as DWG or DXF.

From Wikipedia I learned that both DWG and DXF should also support 3D models, so I guess I'm doing something wrong again Can anyone perhaps explain me how to do this? Thx!

dirk_van_der_vaart

I started allover, and you can edit every dimension.
I started with a quarter table, then mirror sketch and add another spline..

https://cad.onshape.com/documents/f01fdc508d2c5ed01ca37ede/w/c2ddb1e8cada19f649ce7ee5/e/0b900a3926b574bacce053a2

Roberto_Verduci

masta_killa said:

Thanks again Roberto!

I now have managed to complete a first draft of my desktop with everything in it!! (I still have to look into those "sweep self-intersects" for my wifes desktop)

I wanted to send this draft of my desktop to the company that does the CNC and ask if this is possible for them to make and how much it would more or less cost. They told me to send them a DWG or DXF file, but I'm not succeeding in exporting the 3D model as DWG or DXF. Only when I right click something 2D, like a sketch, I get the option to export as DWG or DXF.

From Wikipedia I learned that both DWG and DXF should also support 3D models, so I guess I'm doing something wrong again Can anyone perhaps explain me how to do this? Thx!

Usually, when they ask you for a DXF or DWG you have to create a 2D drawing of the part. They probably need it to get a rough idea and give you a cost. It's quite strange that they didn't ask you for a 3D step.

You can easily fix all this by sharing the Onshape document with your supplier so that, in total autonomy, he can download what he needs (step, dwg, dxf, pdf, etc.). Remember to also create the drawing before sharing and enable the export option.

nick_papageorge073

If the company is asking you for a dxf, that means they can only cut in 2 dimensions. And all the cut edges will have straight 90 deg edges. All the curves you are putting on the edges with the sweep and the fancy surfaces you are modeling are a waste of time.

Rule #1 in product design is to design for the manufacturing process. Talk to the company with the CNC and find out what their capabilities are. Then come back and change your design to match, or find another company.

To be honest, one-off projects like you are designing for your family and your friend are probably cost prohibitive to send to a cnc shop, unless the owner is your friend and doing it for some beers. You are probably better off getting hardwood plywood from your local lumber dealer and cutting this by hand with a jig saw.

IMO:)

dirk_van_der_vaart

Or let them do the outline first and finish with a mill like this.

masta_killa

Thanks Dirk, that looks like a very efficient way to draw it...

Thanks Roberto, I've send them the links and asked if they could work with it...

robert_stiles

Great, lots of discussion on this! @nick_papageorge073 is bang on here - this is exactly the point I was making early in the string. What is the capacity and machining skills of the workshop?

We specialise in extracting 2.5 axis CNC machining data (from a parametric library of designs curated through a configurator that runs in other CAD packages, like SketchUp - but that's another story). I guess our progress is different, because we do not own or operate the CNC machines. We create the data sets for others to go to machinists and workshops, and this means we don't know what machines they have, which CAM software they run etc.

Typically, 90% of workshops only have 2.5 axis CNC (here in the UK), so as @nick_papageorge073 suggests, they would take dxfs, and are essentially working in 2d, but they can control the depth the tool drops also, in the Z plane. Some machines and CAM software can ramp up and down also, running engraving procedures with a cone tipped tools. Although its possible do multiple passes ramping up to get any curved profile you need, not all CAM software can do this, not all operators can do it ! it might take a longer time to program, and it will take ages on the bed - I expect you will be charged per minute on the machine. 

Up from this is 5 axis, where the head can tilt, and rotate. A lot fewer workshops have 5 axis over here. The only way to present the data is as a 3D step file or similar. It is placed in the stock and the CAM package works out all the passes and tool head rotations etc. To create a custom profile like I see here, it will do a number of passes, the more passes the better the resolution, then someone sands it off by hand I expect. It would not be cheap.

You will find workshops have several coving tools and cone cutters for table and desk edges - similar to as @dirk_van_der_vaart suggests. They can run these around the outside cut line, or have 2 or 3 tools they run in stepped passes to create a more gentle profile. But, it will not be the exact custom profile you have modelled. Or you can get profiling tools specially made. In the old days, a joiner would make a bespoke cutter on the grinder for the spindle moulder in order to match the profile of skirting in a room. You don't see this so much any more.

HPL is a high pressure laminate ? not sure how much wood is in it. Its more of a plastic appearance, and is primarily used for cubical doors in washrooms in commercial builds here. Its bomb proof stuff. Personally, I'd go for a Plywood, maybe a 24mm birch ply, with an oak veneer? you can get that off the shelf.  Then CNC a rebate in the top surface and bond this stuff on flush to the surface, local to the work area.  

https://view.publitas.com/forboflooring-uk/forbo-flooring-systems-furniture-linoleum-samplebook/page/2-3

Makes for a great desk surface, but maybe not in a school or high impact environment.

Good luck, let us know how it goes. 

dirk_van_der_vaart

@masta_killa
You spend some time to design a nice desk, no invest in some real nice material, a solid material
https://www.lxhausys.com/eu-en/products/himacs/aurora-bianco

masta_killa

Thanks again for all the replies!

Although things have been going slow, I've not been sitting still...I've now completed the 3D designs and spent quite some time finding a 5 axis CNC that can help us out (As you predicted, this wasn't easy, I found only 2 and they are not nearby - I still don't know the price though, that's the next step ).

Just to be clear: I've already acquired the HPL (High Pressure Laminate) material for the desks for free (my friend worked at the manufacturer). This is indeed the same material that they use for cubical doors in washing rooms or swimming pools, only the plates that I have are much thicker and actually meant for using as a design desktop material. When properly used, this is can be used for a very tough and durable desktop.

As I already have this material and got it for free (while it is normally very expensive), I also want to use it and switching to another material is not an option.

My black desk with aluminium cores for example is using this material:

https://www.nextproducts.at/hersteller/fundermax/news/alucompact-interior-erobert-die-interior-welt/43648144

My wife's and friends desk are with a white Fundermax HPL plate (without the aluminium core)

Here are the latest versions of all 3 desktops:

My desktop
https://cad.onshape.com/documents/c6b0d04bc102f3a914533702/w/44750f3e274a044e3d786c29/e/805d6bf6490b1fa1d08984f5

My friends desktop
https://cad.onshape.com/documents/467f4a7358f5de2576a29f37/w/9f051e82c46d0ea5b7b4c6c2/e/3c4298adcfad844fad90e01b

My wife's desktop
https://cad.onshape.com/documents/aaf548c541c9764180b26427/w/f998972bc769f5686430aa62/e/6fa28e73c3582f684d451e11