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Learning CAD with Alibre Atom3D

Discussion of the series starting in MEW 274

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Alibre Atom3D

Alibre Atom3D

Thanks to the generosity of Alibre, Model Engineers' Workshop Magazine is able to offer every reader of Model Engineers' Workshop a free six-month licence to Alibre Atom3D. Alongside this great opportunity, starting with issue 274 of Model Engineers' Workshop we are running a detailed tutorial series in the magazine. This page will be the 'hub' for links to example files, tutorials and more so make sure you drop in regularly to keep up to date!

Tim Taylor 211/01/2019 08:09:32
43 forum posts
8 photos

2 thru 6.......can't type tonight....

David Jupp11/01/2019 08:10:16
580 forum posts
13 photos

Tim, what I assume to be the first plane in your description can perhaps be created more easily - see image.

cone plane.jpg

Apologies in advance if I mis-interpreted your method.

JasonB11/01/2019 08:25:41
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1381 photos

A lot will depend on how you want the hole to end , for a flat end I did this and Iassumed your hole angle of 25degrees is not the same angle as the slope.

Create a plane at 25degrees to the vertical

25 plane1.jpg

create 2nd plane where you want the hole to end parallel to the one you just created

25 plane2.jpg

To make it easier placing the circle create an axis where the two planes cross

25 plane3.jpg

Draw circle on 2nd plane using axis to locate

25 plane 4.jpg

Cut extrude to beyond the outside of your cone. I have made the part transparent so you can see extent of hole

25 plane 5.jpg

If you don't mind how the hole ends then just create the first plane and draw the circle on that and cut to vertical plane

25 plane 6.jpg

result

25 plane 7.jpg

Edited By JasonB on 11/01/2019 08:26:49

Tim Taylor 211/01/2019 08:40:16
43 forum posts
8 photos

David,

I think what Tom is after is something like this pic (transparency set so hole is visible)

cone.jpg

TomK11/01/2019 10:06:14
67 forum posts
18 photos
Posted by TomK on 10/01/2019 23:18:22:

Hello Been learning Alibre Atom3D. have run into a problem with creating a hole in a cylinder at an angle.

Can anyone show me how to put a hole half way along a tapered cylinder at an angle of 25 degrees to the axis of the cylinder to a depth of half the cylinder diameter..

Cylinder is 0.5" dia at larger end an 0.25 " dia at small end.

Thanks

Tom

Hi

Thanks to all that have replied to my question. The information supplied has answered my question.

Thanks

Tom

David George 111/01/2019 13:46:10
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578 forum posts
193 photos

Hi I have been trying to model a bevel gear but have come to a standstill. I have modelled the outside shape in sketch and then rotated it to make a gear shape then extruded the bore and keyway but I can't work out how to cut the teeth from the blank gear shape.

David

JasonB11/01/2019 13:50:44
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14344 forum posts
1381 photos

David, are you after an exact bevel gear or just something that will look like one on a model?

David George 111/01/2019 14:11:45
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578 forum posts
193 photos

One that looks like on a model as it is a bought in item from decal.

David

David Jupp11/01/2019 14:15:37
580 forum posts
13 photos

For bevel gears take a look at this this thread on the Alibre user forum. I think the part file in post #11 is the easiest to download and play with, but you'll probably need to read earlier posts to understand how to use it.

I should mention that I am not skilled in the fine detail of such gears, so I can't vouch for the equations used etc. The basic approach to the modelling should give some ideas.

I have checked that the template does indeed work with the current Atom3D - just open the equation editor and change the Z values, then wait for the model to update.

EDIT - later in that thread is a version for producing skewed bevel gears.

Edited By David Jupp on 11/01/2019 14:35:42

JasonB11/01/2019 14:42:06
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14344 forum posts
1381 photos

I came up with this while David was typing

Similar to his post earlier today create a plane to the sloping side of the gear blank

bevel1.jpg

Then sketch your gear profile on this, I just did a simple straight sided form for this example

bevel2.jpg

Cute extrude this to the inside edge with some draft

bevel3.jpg

Then make a circular pattern with the number of teeth you want, I then rounded a few edges to get something a bit more like a gear

bevel4.jpg

bevel 5.jpg

 

Edited By JasonB on 11/01/2019 14:57:16

Tim Taylor 211/01/2019 15:18:22
43 forum posts
8 photos
Posted by David Jupp on 11/01/2019 08:10:16:

Tim, what I assume to be the first plane in your description can perhaps be created more easily - see image.

Apologies in advance if I mis-interpreted your method.

Nope, I missed using the tangent slope function. We got the same result, but your way is simpler.

Thanks,

Tim

Chris Gill11/01/2019 17:03:05
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37 forum posts
15 photos

After lots of messing around I finally managed to model something I may, one day, try to make.

I even got the various items working and it highlighted several small problems in the original design. Thanks for all the expert comments on this thread.

I have to admit I do keep hitting frustrating problems - reference lines that don't stay put and may vanish without trace, stack dumps and sketches that were editable before I clicked Save and then become locked in some way. Looking on Alibre's forum it seems even the professionals are having problems.

eh cataract.jpg

eddie dicker11/01/2019 21:01:44
1 forum posts

Has anyone had issues with the top menus disappearing when saving?

I bought a new graphics card (its a Nvidia gigabyte 1030) as my old one wouldn't run the software at all.

I looked the issue up on line and it said the graphics drivers can be an issue; so I downloaded the latest from Nvidia and thought all was good.

But I just saved that latest bit of the magazine model and its done it again?

Lionel Pullum11/01/2019 23:05:01
8 forum posts
1 photos

Hi guys

I think I have found a possible bug in AA3D. I'm trying to fillet a cutout made from lines and ellipse segments, but I cannot select the elipse segment, see the attached figure. Fortunately the workaround is fairly simple, just create a circle the same radius as your filet, constrain it to be tangent to the required lines and trim, as shown. However if this is a bug can it be put on the bug list and addressed

BTW David, thanks for the info about spline input, I was in the middle of nowhere (Australia is large) and could not access the web

fillet workaround.jpg

Andrew Johnston11/01/2019 23:05:53
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4319 forum posts
511 photos
Posted by David George 1 on 11/01/2019 13:46:10:

Hi I have been trying to model a bevel gear but have come to a standstill.......................

This is how I modelled a bevel gear, although be aware that I use Alibre Expert. First I calculate all the parameters. Then I set up the construction planes and axes to get a plane that represents the outer face of a tooth. Then I draw a cone that represents the root angle cone. The gear is initially drawn as 1DP.

root cone.jpg

Then a sketch representing the involute function of a single tooth is placed on the plane representing the face angle of the outer edge and adjusted to line up with the root cone. The involute sketch was imported as a DXF gear, the unwanted parts deleted and the DXF exploded to give a sketch consisting of straight lines. All in all a bit of faff:

involute sketch.jpg

The sketch is then lofted to a single point at the origin to form one tooth:

single tooth.jpg

There seems to be bug in Alibre here; the loft won't work to a point even though the manual says it will.. I needed to draw a 2 thou square, 7 thou above the origin, and then the loft worked. Note that the outer edge of the tooth isn't a good fit. That's because the sketch was drawn on a plane rather than projected onto the cone that represents the outer surface of the gear. Next is a simple circular pattern for 16 teeth, although it takes a while to compute:

all teeth.jpg

Finally a nunber of simple revolve cuts tidy up the model so we have a proper gear:

complete bevel.jpg

An assembly can then be created to visually check meshing:

assembly.jpg

Andrew

Andrew Johnston11/01/2019 23:17:15
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4319 forum posts
511 photos

Thought I'd better split the previous post into sections in case I got dumped for rambling on for too long!

Although the model creation is involved I needed it to accurately represent the gear as I would be making real gears from the model. The gears above were created as 1DP; to get the final 16DP gears it's a simple scale by 1/16. All the little errors created in the original modelling usefully get reduced by the scale factor. After some faffing with the CAM program the bevel gear can be machined on a CNC mill, with a 1mm ballnose cutter:

governor bevel gear cnc.jpg

And the gears fitted on the governor:

governor pulley pinned.jpg

The meshing is smooth. Some while back at a SCMTEG meeting a member, who is also on the forum, was observed having a detailed look at the gears and turning them to check meshing. He didn't comment to me, so either they were dreadful, or he couldn't find any imperfection to point out. smile

Andrew

Andrew Johnston11/01/2019 23:27:13
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4319 forum posts
511 photos
Posted by David Jupp on 11/01/2019 14:15:37:

For bevel gears take a look at this this thread on the Alibre user forum.

Thanks for that David. I'm interested in skew bevel gears, just out of idle curiosity. I'm aware of the work by Kozo and others modelling the gears for logging locomotives. But their pinions have teeth that have considerable lean on them, not at all like the full size gears. I want to have a go at making a set that look like the real thing. I must have a login to the Alibre forum; simply (?) a case of finding out what it is.

I started modelling a set of skew gears. A passable version of the gear is fairly simple using a loft to a point on a circle rather than to the centre of the gear:

skew bevel gear.jpg

But I miserably failed to model a pinion. Skew gears are a complete fudge. As the pinion rotates the gear teeth not only rotate with the pinion but they must also slide along it. So that means the DP must be changing. So the gears can't mesh along a line, but must be at a point. I gather the original gears were rather noisy and prone to wear. On the Alibre forum post it was surmised that the full size originals were mucked about with in wood until they meshed, and then were cast from the wooden patterns. I'd go along with that.

Andrew

JasonB12/01/2019 07:39:39
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Moderator
14344 forum posts
1381 photos
Posted by Lionel Pullum on 11/01/2019 23:05:01:

Hi guys

I think I have found a possible bug in AA3D. I'm trying to fillet a cutout made from lines and ellipse segments, but I cannot select the elipse segment, .........................................

Lionel, ellipses can have a few quirks to them. You may well find it better to leave the corners as they are on your 2D sketch then extrude or cut that sketch. Once you have done that use the fillet tool in part modeling and select the lines of the internal corners you want to fillet and it will pick up all the ones that intersect the ellipse

fillet ellipse.jpg

fillet ellipse2.jpg

 

Edited By JasonB on 12/01/2019 07:49:32

David Jupp12/01/2019 08:25:13
580 forum posts
13 photos
Posted by eddie dicker on 11/01/2019 21:01:44:

Has anyone had issues with the top menus disappearing when saving?

I bought a new graphics card (its a Nvidia gigabyte 1030) as my old one wouldn't run the software at all.

I looked the issue up on line and it said the graphics drivers can be an issue; so I downloaded the latest from Nvidia and thought all was good.

But I just saved that latest bit of the magazine model and its done it again?

Eddie - if the Ribbon gets replaced by a Red X - this is a known issue caused by a Windows update - see this article for explanation and a way to resolve it.

John Hinkley12/01/2019 11:12:36
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650 forum posts
206 photos

Having come to the conclusion that my design for a four-cylinder engine will only ever be a virtual construction, I have ditched the water-cooled version in favour of an air-cooled one. This has massively simplified the block and head design and allowed me to progress a little further. Spurred on by the recent discussion in this thread concerning the use of the sweep tool, I have smoothed out the inlet and exhaust ports to follow an angled path from head side face to valve throat. Very satisfying - but it took some figuring out with the new planes and axes to insert. Not helped, I suppose, by my use of angled valves and ports! Keeps the grey matter working, though.

Here's what it looks like at the present stage of development:

Air-cooled engine assembly

John

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