Dabbling in Fusion 360

When you're ready Rob, you know where to email the STL file for a test print to.

Suggest you add a central spigot to locate the chimney - you can always drill it out once the glue has set, or used as sprue if you send them to be cast via lost wax casting.

Paul

 

Hi Rob

If you wish to have the chimney hollow, create a circle sketch aligned on center, the diameter of the hole. Then extrude the sketch and delete it from the chimney model.

Following on from the STL you sent me to test, I have loaded it in to Chitubox (available free of charge from Chitubox Download )

Supports added, I have copied the model and turned it upside down. Supports were added.



The job was then sliced with a layer height of 0.05mm

Transferred to the printer and a 2h10m wait until we find out how well they turned out

Paul

 

Prints removed from build plate and rinsed to remove uncured resin, then popped into the ultrasonic bath for 5 min - I used AnyCubic's Eco resin. Another rinse in water .. and

Unless there is a risk of warping, I remove the supports before curing - tends to cause less damage as they are still soft.

Now a final wash in IPA, dry off and then cure and were done.

Paul

 

Just for info

The supports we're added manually, and were a combination of Light , Medium and Heavy



Viewed from the underside the two central squares are the heavy supports, preferrably this would be the lowest point. As these are both hidden and will provide the anchor to the build plate.

Because the Heavy supports wont make contact with the model until later, I used medium supports around the locating ring Rob designed, these will easily cope with the peeling forces for the start of the base.
Like wise the light supports will cope with the start of the build, by the time peel forces start to get larger the medium and heavy supported areas will have all merged together.

My preferred spigot design is as below



The central spigot is approx 6mm (or larger) dia and the lowest point of the model.
This allows several heavy supports to be placed on the spigot, light supports on the outer rim, and add a few medium supports between 1/3rd & half way from the rim to the spigot to help the light supports until the whole model is supported via the heavies.

I know Rob prefers a hollow chimney so I'd do that as follows



Once the model is printed &/or fitted the hollowed can be drilled out (hand drill, broach or reamer only as these are rather brittle). For a bigger hole increase the size of the spigot at the design stage.

Note the intersection between the chinmey base and the spigot, I have applied a fillet to strengthen the base area, especially as this would be drilled out.

If you are sending these as masters to a caster, they will thank you for a longer spigot as it gives them something to attach to the moulds.

Paul

 

Hi Mossy

The way the FEP works, 2 main functions, 1. to hold the resin into the vat, 2. let the UV light through it to cure next layer of resin to the previous layer or to the build plate for the first layer.
Tensioning the FEP is required to both seal the vat, but also to provide a flat surface. The FEP also needs to be flexible enough to start a peeling action as the build plate rises after each exposure. The resin after exposure is still fairly flexible, so too slack a FEP sheet may allow the FEP + print to move with the build plate and prevent separation, with repeated exposures the print will stick to the FEP rather than the build plate. On the other hand too tight and the FEP can't flex as much so the whole print will release at once giving a Ping sound, but the amount of force required may prevent the release or even the supports to fail.

Once tightened you can't slacken it off as the FEP has been stretched. However if you slow the lift speed and raise the lift height you can compensate for it being too tight.
Another disadvantage of over tightening, is the FEP will stretch over time, if you fully tightened it at the start, then you have no adjustment after the FEP strectes, so you end up replacing the FEP earlier.

Another word on FEP's, any sign of dings in the surface I'd recommend replacing it, a FEP is far cheaper than a new LCD screen after resin seeped through a small hole in the FEP and cures to the screen. I've had this happen once on my Photon and fortunately managed to remove the cured on resin from the screen surface with IPA, Acetone and a scalpel blade. Not a procedure I wish to repeat.

As Sean Connery once said - "Never say Never" it may bite later.


Paul

 

That's the movie, he'd said to his wife he'd never play Bond again, so when he played the part in movie Never say Never again, his wife reminded him, and they used it for the movie title.

Paul

 

pt 2 continues

The STL file from Rob was loaded into Chitubox



and again a copy turned upside down and supports added



Transferred to the printer for printing - estimated for 2h 7m

Back soon

Paul

 

And as if by magic

The prints have only been washed and then the supports removed.

Some may have wondered why I print a copy upside down, as the base of this model is finer, removing the supports can cause damage the fine edge
as can be seen on the photo below

So in this case I would print further prints upside down, as its easier to file down the pips on top of the chimney, than try and rebuild the flange rim.

Rob - hopefully I'll get to the post office tommorow and send you the prints.

Paul

 

Hi Rob

If you continue the springs higher - 1 turn beyond the height of the center stem, you can then use a plane to slice through the spring level with the top, don't ask me how to do it in Fusion I've not got far - yet, but is how I would do it in 123D.

Chimneys in the post

Paul