3D cad design sequence

[Gordon]

For zoom I use the mouse wheel

To rotate the part so you can see from other angles hold down both mouse keys and just move the mouse.

You can also use the small yellow view icons which are arranged a bit differently in atom to get to preset views such as top, left side, right side etc I probably use the isometric on the right the most.

Not sure if Atom has the view cube as its only recently been added to pro and works like the F360 one where you can drag it about with the mouse to move the view or click a side, edge or corner.

I finally figured that out but it took a while. In one of the tutorials it was kind of mentioned as an aside.

 

[Jasonb]

This is one from the Atom 3D playlist that shows what I just mentioned plus panning

 

[ajoeiam]

True, as far as I know, no CAD allows you to build with tolerances, maybe higher end software but I've not used them so I can't comment on them but frankly, neither does drawing by hand, in all cases, someone has to put tolerances on the 2D drawings that are sent to the shop for manufacture. You can build in clearance or interference fits but tolerances are why there are still engineers.
In Alibre, and I suspect other 3D CAD, you can in an assembly, insert a new part and to do that use existing surfaces, project to sketch which means pull 2D drawings from existing parts, draw your new part, change hole sizes and make offsets of existing components and dimension everything relative to existing components and then create the 3D part. Then, if at a later date, you change the parts the new one is relative to, your new part will change so it fits the new design. Yes, on paper you could do an overlay and trace your existing parts, this is just easier, more accurate and the design is updated when a change is made earlier in the design tree.
I still often use 2D CAD for simple parts, but more complex parts and assemblies are where 3D CAD shines.

Hmmmmmmmmmm - - - I think I've mis-stated what I was thinking!
There is no place to even use tolerances when one is modeling!
So when you insert a dimension and 'constrain' it its most often a nice neat number - - - - - NOTHING about tolerances.

My issue with constraints - - - - its specific to FreeCAD - - - - again I can't afford to play with any of the others so there may be differences - - - is as follows.
When I make a workbench the top is a plane.
I can have physically 'constrain' it in a number of different ways. (Say I'm using angle iron to define the frame under the 'official' top.)
I can make sure that both verticals and the horizontals are cut the same length.
I need to make sure that my first vertical and horizontal are at 90 degrees to each other ( a number of techniques can be used to do this - - - physically at least). Then the third member is at 90 degrees to the opposing member (if you start with a vertical and a horizontal and your third is a vertical - - - you get the idea). Dropping in the 4th member should have a 90 degree connection to both of its mating end points. Practically I've learned that even if all corners are quite square you can still get racking (twist) in the structure. (It is not simple nor easy to fab square and true tables and benches!!!!)

Now when I want to 'constrain' this as a model - - - well - - - in FreeCAD there is only ONE way to do this and only ONE specific order of operations.
Physically I can use equal part lengths and a constant 90 degree angle and I can assemble things in at least 2 if not 3 different ways and I get the same results. (tack 1st pair together - - accurate angle, then tack in the next two pieces because I know that with accurate cuts and one accurate angle I will have my rectangle - - - or I could make 2 pairs checking each and then connect the pairs - - - - or I could work clockwise around the parts or counterclockwise around the parts - - - - it just doesn't matter what order I do things - - - - I get the same end result.) In the model constraints only one system works to give you a constrained rectangle - - - - no variant works - - - only ONE order of operations.
This gets really frustrating when you realize that even though you have what looks right - - - you can't add the 3rd dimension - - - - you haven't followed the 'correct order' of steps in the constraints. Get immensely frustrating when you have something like a real work item where it isn't a nice neat rectangle - - - its like a bunch of connected rectangles but with them as one piece - - - finding the one dimension that isn't constrained - - - - baffling - - - should just be able to define 90 degree angles and use lengths and its all good (see physical example) but you happened to add a constraint to line #6 before you did something else and the only way to fix things is to start over.

(Doesn't help when the people doing the coding can't get the difference between pipe and tubing - - - in fact sometimes conflating the two. Its why I haven't spent more time trying to learn how to use FreeCAD - - - - lots and lots of devs and almost no leadership - - - seems like most every dev has a different idea on how to get things done - - - no consistent systematic procedures - - - - but wow - - - is it flexible (if I could only figure out how to use it!!!!).)

 

[Richard Hed]

Two bits Twin on Model Engine Maker site

OK, I found it. Thanx.

Are you working on it in Alibre? I'm curious if you have tested out the 2D/dimming feature yet? I do the dimming then export it to a pdf. If I wants a hard copy, I can print it. I can also easily send it to whomever may want it. I found a method in which you can make multiple pages on a single pdf document which I find extremely convenient as before, I would make a single page (with however many parts dimmed on it) and print that or send it. But now it is so much easier, as single doc to send or print.

 

[Richard Hed]

One of the problems that I find on this and many other software programs is that they do not tell you the procedure to do various operations. In Alibre and other cad programs the videos show thing happening like zoom, rotate etc. but does not tell you how to do that. A good example is I was not able to figure out how to return to my original fully defined sketch and finally discovered that right clicking on the sketch brings you back to the original by editing. Some simple navigation tips that experienced users do without thinking are a complete mystery to a new user. I watch a video and thing happen in a few seconds and I say "How in **** did they do that?).

Your mouse it two buttons with a roller? The roller will control 'zoom'. Press the two buttons together a that will rotate, besides the 'rotating box thingy' in the RH top corner.

Yes, those 'mysteries' are what cause peeps to give up in frustration, however, it is almost certain that a little extra work at it and maybe some advice from yuour friends, and you will succeed.

 

[Richard Hed]

OK Some dumb questions. Since I work alone and do not have to share my stuff with others I do not know how to capture a screen or part of a screen so that I can post it to this forum. I can do it in Chrome but not from Alibre. Also folks add notes to those views. How?

I presently am trying to add a series of holes in a circular pattern. There is a command for that but I cannot make it work. OK remains greyed out so I am missing something.

In my sketch there is a circle shown from probably one of my attempts and I cannot select it or find any way to delete it.

When I try adding a circle to a face I want it to be on the Y center line but the blue box placing it on the center line does not appear. I have been deliberately placing it off center and then dimensioning it to 0. I am sure that is not the correct method.

OK, first in your circular pattern extrude it, THEN put your holes in the extrusion. If you have circles Inside some other 2D, or any lines crossing, you cannot extrude it. Alibre, as far as I know, is strictly one step at a time. Try that and then let me know if it works or if I am on the wrong track.

as far as that last problem, the only thing I can thimpfk of is that you're trying to manipulate the circle when you have some other command going or maybe you are working on eht wrong plane or surface.

 

[Bentwings]

as far as tolerances go you build then in allow for shaft clearance either in the hole or on the shaft it’s up to the shop to measure snd calibrate machines almost any modern cnc machine will be capable of 4 place accuracy when the parts are assembled they will fit if you modeled them within the shop machine capabilities Ive had countless dowel pin hole machines for perfect fit and location it’s not necessary to tolerance things that aren’t critical some milling machines can leave an out of round hole if too small of cutter was used but that’s the shop problem they know the tools I’ve probably had more issues with purchased parts not fitting because the size of features was not given close enough a fractional given size is asking for a bo fit it’s worth a phone call I have a lathe spindle that’s the bearings don’t fit correctly it’s a China made thing so I can’t expect much us made bearings are more precise than any tool I have to measure them they are exactly what the spec sheet says according to my tools but the spindle is .003 oversized of course the bearings aren’t going to have a slip fit the first one split when it got pressed on but what could I expect now the new spindle will have to be either ground or possibly I can get a shop to fix it I could probably have a whole new one custom made for less than the repair I’ve already tried polishing one spindle but I don’t have another lathe or I’d just machine my own .
True, as far as I know, no CAD allows you to build with tolerances, maybe higher end software but I've not used them so I can't comment on them but frankly, neither does drawing by hand, in all cases, someone has to put tolerances on the 2D drawings that are sent to the shop for manufacture. You can build in clearance or interference fits but tolerances are why there are still engineers.
In Alibre, and I suspect other 3D CAD, you can in an assembly, insert a new part and to do that use existing surfaces, project to sketch which means pull 2D drawings from existing parts, draw your new part, change hole sizes and make offsets of existing components and dimension everything relative to existing components and then create the 3D part. Then, if at a later date, you change the parts the new one is relative to, your new part will change so it fits the new design. Yes, on paper you could do an overlay and trace your existing parts, this is just easier, more accurate and the design is updated when a change is made earlier in the design tree.
I still often use 2D CAD for simple parts, but more complex parts and assemblies are where 3D CAD shines.

 

[L98fiero]

Where is this "limited hole option" ? I would like to use it but I have never seen it.

Here's the hole function and it is in Atom
https://www.alibre.com/AlibreDownloads/Alibre_Atom3D_Exercise_Manual.pdf

 

[Jasonb]

Here's the hole function and it is in Atom
https://www.alibre.com/AlibreDownloads/Alibre_Atom3D_Exercise_Manual.pdf

That is just a circle being used with extrude cut being used in that pdf. Das I confirmed yesterday there is no hole function in Atom.

 

[Jasonb]

Dick, I've produced quite a few drawings to share either by public link or to go into magazines with a build article. I do single sheets and upload or send a pdf to the publisher as they prefer if to a multi page pdf. Multi page is good for onscreen viewing as you can just scroll down to the part rather than open several pages though I try to group associated parts onto one sheet and give a suitable title rather than just each pdf having a drawing number.

There is a n option to use the design dimensions which will put every dimension onto the 2D paper as you placed them during the initial sketching stage but unless you are very particular at those early stages it can come up as a right mess. I prefer to click "more options" the tick all and finally untick "use design dimensions" Then I will layout the new dimensions neatly

Example set of drawings here

 

[Gordon]

OK, first in your circular pattern extrude it, THEN put your holes in the extrusion. If you have circles Inside some other 2D, or any lines crossing, you cannot extrude it. Alibre, as far as I know, is strictly one step at a time. Try that and then let me know if it works or if I am on the wrong track.

as far as that last problem, the only thing I can thimpfk of is that you're trying to manipulate the circle when you have some other command going or maybe you are working on eht wrong plane or surface.

I found that the problem was in finding the correct axis to use. If you use the wrong axis you can end up with all of the holes on top of each other. Most of the problems I am having is just not knowing what step that I am missing.

 

[L98fiero]

That is just a circle being used with extrude cut being used in that pdf. Das I confirmed yesterday there is no hole function in Atom.

No, give it a try, it will produce counterbores, countersinks, recessed countersinks, tapers, flat bottom holes, drill point holes, blind or through and a number of different series of threads to different depths, far more than a circle extruded cut. If you expect a hole tool to produce a shape other than circular you aren't really looking for a hole tool.

 

[Jasonb]

Which page of the pdf are you seeing that on, for example starting on page 38 they select the circle tool, sketch a circle and then cut it through all. That is not the hole tool like you get in pro and expert.

Look at Alibre's comparrison table, threads not available for 3D or Workshop Compare 3D CAD Software | Alibre's CAD Software Features

 

[Jasonb]

Just to confirm there is no Hole Tool in Atom, this is a post by David Jupp who works for Alibre and is an advisor on their own forum and like myself was very active in this thread when MEW mag ran a series supported by Alibre with special deals etc

 

[L98fiero]

Just to confirm there is no Hole Tool in Atom, this is a post by David Jupp who works for Alibre and is an advisor on their own forum and like myself was very active in this thread when MEW mag ran a series supported by Alibre with special deals etc

Yes, you are correct, I have expert so was only going by what I saw online.

 

[Gordon]

Another Alibre hole question. When I place a hole on a sketch surface I can enter the diameter but not the location. I would like to place the circle at X and Y from the origin. The only way I have found to do that is to place the hole someplace away from the origin and then dimensioning X=0 and then Y=a value. It seem like you should at least be able to snap to one axis. If you place the hole too close to the axis it is hard to get the correct dimension input box to enter. I am gaining. I can now make a five minute sketch id 1 hour 45 minutes instead of two hours.

I still have not found a way to take a screen shot of the Aliebe screen.

 

[Jasonb]

Select the circle tool and you will see the cursor as a little circle and the crt point & +, this will snap to lines , junctions of lines etc when the ctr point changes to a blue square.

If you want to enter the ctr point position then again select the circle tool then right click, from the drop down box choose "direct coordinate entry" you can enter a location there for the ctr point

Myself I tend to place the circle near where I want it and enter dimensions from a point, feature or axis

I use the windows snipping tool but you loose things like that coordinate dropdown a ssoon as you activare something else.

 

[awake]

Hmmmmmmmmmm - - - I think I've mis-stated what I was thinking!
There is no place to even use tolerances when one is modeling!
So when you insert a dimension and 'constrain' it its most often a nice neat number - - - - - NOTHING about tolerances.

My issue with constraints - - - - its specific to FreeCAD - - - - again I can't afford to play with any of the others so there may be differences - - - is as follows.
When I make a workbench the top is a plane.
I can have physically 'constrain' it in a number of different ways. (Say I'm using angle iron to define the frame under the 'official' top.)
I can make sure that both verticals and the horizontals are cut the same length.
I need to make sure that my first vertical and horizontal are at 90 degrees to each other ( a number of techniques can be used to do this - - - physically at least). Then the third member is at 90 degrees to the opposing member (if you start with a vertical and a horizontal and your third is a vertical - - - you get the idea). Dropping in the 4th member should have a 90 degree connection to both of its mating end points. Practically I've learned that even if all corners are quite square you can still get racking (twist) in the structure. (It is not simple nor easy to fab square and true tables and benches!!!!)

Now when I want to 'constrain' this as a model - - - well - - - in FreeCAD there is only ONE way to do this and only ONE specific order of operations.
Physically I can use equal part lengths and a constant 90 degree angle and I can assemble things in at least 2 if not 3 different ways and I get the same results. (tack 1st pair together - - accurate angle, then tack in the next two pieces because I know that with accurate cuts and one accurate angle I will have my rectangle - - - or I could make 2 pairs checking each and then connect the pairs - - - - or I could work clockwise around the parts or counterclockwise around the parts - - - - it just doesn't matter what order I do things - - - - I get the same end result.) In the model constraints only one system works to give you a constrained rectangle - - - - no variant works - - - only ONE order of operations.
This gets really frustrating when you realize that even though you have what looks right - - - you can't add the 3rd dimension - - - - you haven't followed the 'correct order' of steps in the constraints. Get immensely frustrating when you have something like a real work item where it isn't a nice neat rectangle - - - its like a bunch of connected rectangles but with them as one piece - - - finding the one dimension that isn't constrained - - - - baffling - - - should just be able to define 90 degree angles and use lengths and its all good (see physical example) but you happened to add a constraint to line #6 before you did something else and the only way to fix things is to start over.

(Doesn't help when the people doing the coding can't get the difference between pipe and tubing - - - in fact sometimes conflating the two. Its why I haven't spent more time trying to learn how to use FreeCAD - - - - lots and lots of devs and almost no leadership - - - seems like most every dev has a different idea on how to get things done - - - no consistent systematic procedures - - - - but wow - - - is it flexible (if I could only figure out how to use it!!!!).)

I am not sure I am understanding - I can constrain a rectangle in several different ways in FreeCAD. I'm not sure what you mean by only one way to constrain it. And of course, how you draw or model it is not the same as how you go about building it. The order of operations in constructing the model need not (and mostly will not) bear any resemblance to the order of operations used to machine the part.

If tolerances were included in the definitions (constraints, dimensions - whatever we want to call them) of the model, I think you would get a very fuzzy model shown on screen, representing all of the possible values for each dimension. Instead, you construct the model to be the "ideal" shape and size. For me, that "ideal" size includes taking into account the tolerances that I will need. IOW, I wouldn't design the model with a 1.000" rod to slide in a 1.000" bore; I'd make the rod .998" or something like that. Honestly though, I wouldn't be able to tell the difference when I view the model on screen, so I'm only going to see the tolerances when I generate a drawing from the model ... during which process I will add the tolerances I want to achieve.

Even if you were going to CAM the part - no, *especially* if you were going to CAM the part - you wouldn't want to give tolerances TO the CNC. The tolerances represent the errors OF the CNC machine. You have to have the CNC shoot for a specific size; you can't give it a range of sizes to shoot for - which one would it pick? Instead, you decide on a specific size for it to shoot for, taking into account the errors that will occur due to the CNC's accuracy.

 

[L98fiero]

The tolerances represent the errors OF the CNC machine. You have to have the CNC shoot for a specific size; you can't give it a range of sizes to shoot for - which one would it pick? Instead, you decide on a specific size for it to shoot for, taking into account the errors that will occur due to the CNC's accuracy.

Not to nit pick but tolerances don't represent the errors of the machine, they represent the allowable deviation from the nominal dimension

 

[Richard Hed]

I found that the problem was in finding the correct axis to use. If you use the wrong axis you can end up with all of the holes on top of each other. Most of the problems I am having is just not knowing what step that I am missing.

Yess yess, LOL, been there done that! Now that that short tutorial has been put here in HMEM by another member, I am going thru it trying to find that 'hole' command (which I haven't found yet), but am glad to be looking, as I am reminded of some stuff I forgot that will be handy and useful.