How to make a ledge

[ianhughes7UFVF]

Hi

I am trying to make a 3d printed frame. The Top Plate is going to be 10mm thick but I want to make it in segements.

This is my first idea:

8 segments, but I needed to make ledges on each side of the individual sections one on the bottom and one on the top of each to be able to join them.

So the sketch I adjusted to look like the last picture, so it will give me a 10mm cut out on one side and a 10mm extension on the top of the other side.

I extrude the section 10mm but carn't seem to make a ledge on the bottom side properly. The cutout needs to be 5mm up.

Hopefully you can understand what I am asking. I have attached the design for you to look at.

Its basically so I can glue each section together with some retention.

Kind Regards

Ian

[lichtzeichenanlage · Accepted solution]

Have you seen this little icon in the red circle?

It looks like a component icon, because it's a component (well done Autodesk). This means, if you insert your design into another design, it is a component.

If you would you have a component first,...

...it would look like this after you've inserted it:

So well done! And the rule of thumb is: If your design just contains one component just don't create a component because it is already a component 😉

Speaking about rules... Do you know Rule #1? This rule of thumb is captured as exception no. 3 

[lichtzeichenanlage]

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@ianhughes7UFVFwrote:.. This is going to become a 3d printed R2D2 Frame project I want to create...

Hmm. Unless it would be 3D printed, you might want to design with clearances in mind. 

[ianhughes7UFVF]

Hi

I am starting to strike some problems as expected.

I inserted the side plate into the Top Plate design. I needed to align it with one of the plates correctly. The only way I could see to do that was add a circle sketch that was dead center between ID and OD of the plates and then draw a bisecting line to give the angle I needed.

I then aligned the Side Plate with the line and then moved it line to line to get it into position.

The problem is, the face of the Side Plate needs to be 20mm from the outside edge of the OD and I carn't work out how to measure and mark the distance correctly. For straight lines I use the measure tool, but here we have a straight line and circle?

Here are some pics.

I carn't seem to attach an export of the file due the fact I inserted the side plate from a different design.

I could export from the cloud but its a different format.

Any directions on how to provide an accessible file and how to measure the distance correctly.

Kind Regards

Ian

[davebYYPCU]

That is the correct format, now that you have inserted a file into the current file.  Sent you a Pm after the earlier post, and before reading this one.

Might help...

[lichtzeichenanlage]

You have a problem with your ring component, because you're mixing root level and component level sketches without any reasons. That forces problems:

You can mix the levels, but you should only do it if the profiles are shared between components. In you're case it makes things only complicated.

[lichtzeichenanlage]

Missed to attache the export...

[lichtzeichenanlage · Accepted solution]

If I would build such a thing, I would like to have registration marks for the assembly. Because auf this, I would add cut outs and than joining is easy.

You could do drill holes etc.,  too.

[lichtzeichenanlage]

I missed the attachment again... silly me.

[ianhughes7UFVF]

Hi

I intended to make as advised a groove for the side plate to fit in as you automatically correctly preferred.

I definitely need to clean the whole design up and make it readable as you showed.

I am getting so preoccupied with new territory I am forgetting the good basic practice I should know from now.

I noticed that you made the groove start 5mm in from the inside diameter. The width of the plate is 30mm so if I want the side plate 20mm from the outer diameter its not going to work is it, considering it is 10mm thick. I may have to take that into consideration. I probably would need to work with the design as you have described it.

I really appreciate your help here. I hope I can replicate it.

Kind Regards

Ian

[TheCADWhisperer]

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@ianhughes7UFVFwrote: 

By the way, don't mow the lawn yet, 

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Well I had to go get it done while the sky was clear.

Back to heavy rain today.

One of the biggest mistakes I have seen designers make when using CAD software is designing "Perfect Parts".

While we can do this on the computer - it is not possible to make perfect parts out on the shop floor or when 3D Printing.  There is always a tolerance associated with every feature, every dimension.

The truly perfect design is when everything will assemble and function as intended even with every possible combination of minimum and maximum feature within tolerance possible for the manufacturing process.  Moving from hand fitting art to interchangeable part design requires an appreciation of tolerance stack-ups.

I have run into too many people who consider that post-process concern rather than designing for manufacture and assembly right from the start.  It is a good habit that should be developed rather than, "Well, I'll worry about that later."  Too often stuff gets "adjusted" out on the shop floor and never documented.  (not to mention the cases of scrapped materials)

 In any case - at the very least - I would add a small Chamfer where these "Perfect Corners) go together.  (see video)

[chrisplyler]

I don't know whether discussions of designing for manufacturing belong in a forum dedicated to the use of the design software, but I love them anyway. Such important knowledge that many people don't even know that they don't know.

@TheCADWhisperer  at one point in your screencast you mention the idea of only gapping one of the butting pairs of faces and leaving the other pair to physically butt together. I think in this design that is preferable. Without at least one pair of butting faces, only the clamping force of whatever fastener is in the hole, and the resulting friction between the overlapping faces, prevents rotation at the joint. Having at least one butting pair of faces prevents that (at least in the theoretical computer universe).

[lichtzeichenanlage]

Like @TheCADWhisperer I've applied some basic clearances to the ring elements. The difference is, that I'v used a parameter to drive those clearances. By doing this, you can change it later easily if you get a different printer or using a different material.

[ianhughes7UFVF]

Hi

I appreciate the effort you all have put into refining the top plate.

I had printed two segments off to see how they looked and went together:

The print is under the size rather than over the size, and with a little inaccuracy of the hole I need to drill out neater, the pieces are joining flush. The bolts are m3 x 15mm at the moment. I am using pla, but I feel it would be handy to do these parts in abs to allow acentone glueing rather than using loctite.

So I like the emphasis that I need to clearly define my work and also improve the joins. I hadn't thought of chamfering the edges. This project will improve as I go I think.

I was thinking about the project over night and you know I inserted the side plate from a different design. I think I would prefer to build the parts in the current design and that's where I am really, really on new territory. I think I will used the bolts to attach over structural parts to the rings, so I would like to create those parts within the same design.

For example, the top plate. I think it would be good to have a cross section that joins from one side to the other.

An 10mm thick plate that has 5mm that butts against the inside curve and perhaps 5mms that sits under the top plate. Maybe more so it can bolt onto the present bolts that are there either side.

I have no idea where to start to do this. I realize I may need to create a sketch and then extrude it to the size and then do some cut work to get the curve. But where to start correctly is the problem.

My aim is to build the whole frame in one file and add the parts on as I conceptualize them.

Kind Regards

Ian

[lichtzeichenanlage]

@ianhughes7UFVF: If you're just afraid of the sanding part, you might have a look at PolySmooth. I wouldn't choose PLA for a different reason. You're spending so much time on this model and the print time will not be low, too. For me the biggest downside of PLA is the low melting point. Put you printed parts during the summer time into a car and let it there - the result might no be not to good for the printed part.  Sometimes the sun is enough. Check this link:

[ianhughes7UFVF]

Hi

I am used to sanding parts 🙂

I was working on the inmoov lifesized robot and that required alot of work to make parts fit.

I was advised when I started out printing that it was easier to start with pla rather than using abs. I realize that it would make bonding alot easier with abs, but I thought there is warping concern's with abs.

I would like to try abs at somestage but considering I have plenty of this black pla, I may as well continue to using it.

Using bolts is my secondary backup due to the lack of using acetone to weld the parts together. Although someone mentioned that acetone does work on pla. I haven't tested it to see.

Kind Regards

Ian

[ianhughes7UFVF]

Hi

Thanks for the two screencasts and the time you went to make them.

I do appreciate the need for fore thought and I can see from what you did the advantage of using parameters.

Its also very interesting to see the brace made in the same design but separate and then joined.

Ironically I haven't used alot of the commands you used in any of my other work, but its a good time to start. Considering there is going to be alot more to add to the build as I go, its all going to be necessary to start getting things right from the start.

Kind Regards

Ian

[ianhughes7UFVF]

Hi

So I printed off all eight segments and tested fitted them. There are some obvious issues.

So I have my circle. Where the holes are should be correct, but I may loose some accuracy when I have to redrill them as they don't come out that clean. The joins aren't that close though. Its like there is a little shrinkage.

As you can see where the ledge is, the top print is a little rough and you cab see the half mm inaccuracy.

When the support material is removed for the ledge, it leaves an angled ledge rather than a flat surface, so when I go to glue these together, I will have a fairly unflat surface around.

I am thinking that this may need to go back to the drawing board to rethink.

We know its nothing to do with fusion, but all to do with my printer, but maybe I need to come up with an alternative method of joining sections.

Any thoughts?

Kind Regards

Ian

[ianhughes7UFVF]

Hi

One way to remove the ledge issue is probably have both ledges on one plain rather than one up and one down. It would mean that every second quater would need to be printed upside down.

I hope you know what I mean.

Like this:

This would allow the ledges to print correctly on the top and sit properly on the print bed.

Kind Regards

Ian