creating an air pressure tank

[coops1]

Hi all I am new to freeCAD so please go easy on me . I am just trying to learn from watching youtube videos .I have managed to create an image in freeCAD of what I want to create but the air tank needs to be hollow and in the correct dimensions ? .I have been mainly trying the create this in parts, is this the right place or shoud I be trying to use sketcher . I could post a photo of it on the forum but cannot even work out how to do that any help would be greatly appreciated maybe pointers towards relevant videos or books any help would be great .
Thanks in advance

[Tilli]

Hi all I am new to freeCAD . . . watching youtube videos . . . post a photo of it on the forum but cannot even work out how to do that . . .

Hi and Welcome

It's very active and helpful here. Good idea to read the IMPORTANT red link above, because the local ninjas generally appreciate maximum info without having to ask and without having to go hunting or downloading off-site. All busy volunteers, so it's just helping them to help us.

From reading the forum for some weeks now, I often see caution voiced over the age of some YouTube videos, because there have been some areas where FreeCAD versions have significant differences.

As for including images and files, I myself missed it at first, but not too tricky once you've found it.

Look below the word-processor area, below the [Save draft] [Preview] [Submit] buttons...

Best of luck.

AttachingImages.png (49.52 KiB) Viewed 1914 times

[coops1]

Hi Tilli thanks for you reply I would never have found out how to post an image without your help.In reference to the youtube videos I have watched many and only realised when half way through that I could go no further.But I still managed to learn some bits n pieces even through I could not complete the task so not all bad .I cannot seem to get the pipe function to work in (part ) I have managed to get around this by creating two objects then deleting one.My main problems is I have managed to create the two filleted 30mm ends of the tank but cannot work out how to hollow them to a 3mm thickness .If I could find a video or instruction of how to make a cereal breakfast type bowl I was thinking I could make two of them then fuse them to the tube that I have created.Does anyone know if this would be possible or is there a better way of achieving my goal.I have looked through the tutorials but cannot find anything that could help me to be honest i'm not the smartest cookie in the packet and it does take me a while to learn but I am determined.If anyone can advise pleas make it as simple as possible if possible
Thanks in advance.

I have tried for over 2 hours to convert the FCSTD file to pdf but cannot manage to do this when I export the only option is as fcstd I have also gone online and tried lots of file converters but none work .My original drawing is all that I can manage to add to the page .I have added a link of my freeCAD attempt but it does not seem to work Sorry.

[chrisb]

I would do this in Part Design with a revolved section

As for the pdf: they are created from the model in the TechDraw workbench. If you want to post images from your model, you can create them with Menu->Tools->Save picture.
If you want to include more, because it is relevant, you can make a screenshot.

You did well to upload the file so we can have a look at it.

[chrisb]

Here is an example with a revolved sketch. I used thickness , which often is a bit picky. It yields a uniform thickness throughout the whole model. If you need different thickness, e.g. for the tube ends you can model the revolution with inner and outer wall.

I changed the radius according to the image above. You had taken the diameter as radius.

Bildschirmfoto 2018-05-27 um 08.34.52.png (19 KiB) Viewed 1864 times

[coops1]

Thanks very much for clearing up diameter as radius and for giving me a starting point ( I would do this in Part Design with a revolved section).
to be honest I all I have managed to do is create a limited design in parts and cannot seem to alter them in parts design warn box keeps saying not a solid object .I will try to find some videos of using part design. In the meantime would it be possible if I could mess around with the tank you made in part design as it might give me a better understanding of the diameter radius and solid object problems I'm having .If it is ok could you please explain how I would go about importing the image to part design .

Thanks again to all for the advise it's pointing me in the right direction.

[chrisb]

If it is ok could you please explain how I would go about importing the image to part design .

You don't have to import it. The file I attached to the above post contains the PartDesign model.

Thanks again to all for the advise it's pointing me in the right direction.

You're welcome. Be careful with the video tutorials concerning PartDesign. Much has changed from version 0.16 to 0.17. There are tutorials in the wiki:

Start with Creating a simple part with PartDesign and continue with Basic Part Design Tutorial 017 which has an accompanying video. I would strongly recommend to work through the tutorials. After that you might continue with some other tutorials and you should be able to model in 0.17 even if the tutorials cover 0.16.

[coops1]

Thanks to all and Chrisb for creating the the cylinder it will be of great help to me,in the meantime I have found some fantastic very informative and easy to follow instruction videos made by bram de vries on youtube I have had no problems as of yet with settings etc, fingers crossed.
Chrisb When I eventually learn and finish my object would you be so kind as to make sure I have completed it correctly ?
Thanks for everyones help now I have a direction to go in and lots to learn
THANKS HEAPS

[Tilli]

. . . thanks . . . is there a better way . . . My original drawing . . .

No problem, we all start off in a similar position in unfamiliar territory. I might have got the basics of the forum-interface now, it's just the FreeCAD software still massively overwhelms me! LOL

"How long's a piece of string?"

You ask about "a better way..." Heheheh. What's the old expression, ten experts in a room, twenty different opinions?

Even during my few weeks here, reading just a tiny fraction of what's been posted, I've seen radically different ways of tackling tasks. The way they think, the tools they're familiar with... massive variety, and really fascinating! Most of it still goes over my head of course, but the pennies are gradually dropping and the dots are slowly joining.

One thing I've seen repeated a number of times, is the need to model strategically, taking account of the quirks and limitations of the available tools. Another, related, is aiming at simpler, more robust, more efficient models.

That's great, but tough when you're still unfamiliar with the tools. Even moreso when the volunteer-project Documentation lags behind the Code and renders the internet-ubiquitous imperative "RTFM!" somewhat specious, although I'm pleased that I've hardly seen that approach here on the FreeCAD forum.

"My original drawing"

Just a question/comment off the top of my head : in your file your own filleted parts look well rounded, looking tangential to the main cylinder's walls; in the picture you posted, it looks angular at the join. With the OP title's "pressure" in mind, are there any health and safety considerations here? Are there any threshold criteria imposed by the Physics of the application and the materials..?

I know Oxygen and other gas cylinders have highly rounded profiles to avoid concentration of stress.

Just a thought.

[coops1]

Hi Tilli great point( Are there any threshold criteria imposed by the Physics of the application and the materials..?) I have not considered this as the maximum pressure is going to be around 100psi. The tank will be made from 3mm aluminium I presumed it would be fine but now you have mentioned
it I will make the ends similar to rounded side of a scuba tank and seek more advise before it's made just on the safe side.
Thanks for your insight much appreciated