Scale and size. Does size matter?

[The Spadgent]

Hi guys. I have been around BM for a few years now but am super new to 3D printing. @hendie and @TheBaron made me do it. 😱🧐😂

I do know 3D modelling (3D studio Max) really quite well but have a few questions I hope the hive mind might help with.

I set my max units to CM as this is the scale I’ll work with on most projects. My work setting is in M. I build a test cube to the correct scale of 1cm and brought it into Chitu box. ( I have a Mars 2 pro ) on import the file was called out for being too big and I had to re scale. This can be done in chitu box but surely the scales should be in sync? I reset transforms on the asset before exporting to an .OBJ. Also is .OBJ the best file format to move between programmes?

 

Thanks for any help.

 

Johnny.

[Schwarz-Brot]

Printers and the respective software and slicers usually love and expect .stl files.

[The Spadgent]

Post error sorry.

[The Spadgent]

56 minutes ago, Schwarz-Brot said:

Printers and the respective software and slicers usually love and expect .stl files.

Oh ok so I’ll export .stl from Max and see what happens. Thx

[hendie]

for what its worth, I use SolidWorks and usually draw in millimeters, and export by STL

I've had times when Chitubox has informed me the model is too big - I ignored the message and the model was fine.

 

3 hours ago, The Spadgent said:

Also is .OBJ the best file format to move between programmes?

 

Between 3DS Max and Chitubox?   I'd say STL is by far the most common, but it's not the only format.  There's no reason why you couldn't use an OBJ file or other file format that Chitubox accepts

 

 

 

 

[ICMF]

Most likely it was confusion between mm/cm, as slicers use millimetres by default.  

[The Spadgent]

I know it’s odd and I would work in MM but max is a funny bugger and it’s tolerances are off on small or large things. ( not tolerance as such morethe view port doesn’t work and using the middle wheel is either too much in smaller or not enough in bigger items. ) Even thought it shouldn’t matter in 3D space really. I’ll give it another bash and see what happens. Thanks for the info. 😍

[The Spadgent]

It looks like you can export in .STL  max and Chitu box really don’t like each other open at the same time though. 😬

[The Spadgent]

My set up was MM but scene was still in M all sorted now. 
look at the size difference. The big cube is 1cm.

Look for the arrow on the left, that was what size my model was at. 🤣

 

by the way. Doing more tests. Do smoothing groups come across into Chitu box?

It seems not in this export.

 

I exported a .obj file too with smoothing groups. Alas still blocky. I’ll just have to up the Res before export.

 

Johnny 3D

[The Spadgent]

@hendie & @TheBaron or indeed the hive mind. seriously considering getting the mercury curing station. It’s on offer at the mo at around £90. My first prints are in the garden curing as my window doesn’t face the sun. I’m thinking as the winter is coming this is going to be more of a pain and messy. Can you cure through glass in your room and do you need a lot of sun? 
Sorry so many questions. 
 

John.

[TheBaron]

48 minutes ago, The Spadgent said:

seriously considering getting the mercury curing station.

If you can pony up the extra Johnny, get the wash AND cure version of the Mercury station. In terms of drastically lessening exposure to chemicals inside the house (in both liquid and vapour form) and sheer speed of cleaning/curing parts afterwards, it's a necessity imho if you're going to be doing this on a regular basis.

 

Here in Ireland the sun curing option was never going to be feasible for me anyway....

[hendie]

1 hour ago, The Spadgent said:

Can you cure through glass in your room and do you need a lot of sun? 

 

That's the way I do it Johnny.  I know household glass blocks a lot of UV, but enough gets through to do the job.

I prefer not to have strong sun in order to prevent any chance of warping due to heat.

Any UV lamp would do though I would avoid the small enclosed types like nail curing stations as they generate a lot of heat

[The Spadgent]

2 hours ago, TheBaron said:

If you can pony up the extra Johnny, get the wash AND cure version of the Mercury station. In terms of drastically lessening exposure to chemicals inside the house (in both liquid and vapour form) and sheer speed of cleaning/curing parts afterwards, it's a necessity imho if you're going to be doing this on a regular basis.

 

Here in Ireland the sun curing option was never going to be feasible for me anyway....

Thanks Tony.  I did the cure and wash up last night after my first print. It wasn’t super messy but I was all ready for it (clean bench) and it still got a bit out of control.  I didn’t realise how dangerous it all is. 🤯 also skipping around the garden looking for a patch of sun this morning then thinking about doing that in the winter or if I want to cure at night.  It worked well but the Amazon flash sale today was the nail in my wallets coffin.

 

1 hour ago, hendie said:

 

That's the way I do it Johnny.  I know household glass blocks a lot of UV, but enough gets through to do the job.

I prefer not to have strong sun in order to prevent any chance of warping due to heat.

Any UV lamp would do though I would avoid the small enclosed types like nail curing stations as they generate a lot of heat

Thanks Alan. My first test prints did cure but I was concerned about all the things mentioned to Tony plus getting rid of uncurled resin is an issue. I know I could leave it outside but I guess I can just blast them in the booth before getting rid of them. 
feels like a whole new world. 😇😀
 

Everything said a yellow box in on its way. 💛

[The Spadgent]

Plus I can clean the build plate at the same time with the new wash station.

here’s the first test prints.😅

And after curing. / still curing.

One thing I would say though they were hard to get off the plate. I saw a guy on YouTube rock a Stanley blade under one edge then use the spatula so I did that. It worked but Twas a bit hard. 
 

pleased with the results though. 

[hendie]

Johnny,

I wouldn't use metal on the build plate in case you scratch it.  I got these plastic razor blades  from Amazon and they do a great job.  ^ months in and I'm still on the first blade

 

 

 

[The Spadgent]

3 minutes ago, hendie said:

Johnny,

I wouldn't use metal on the build plate in case you scratch it.  I got these plastic razor blades  from Amazon and they do a great job.  ^ months in and I'm still on the first blade

 

 

 

Ok I’ll get some of those as it did mark the plate a little. Daft really they give you a metal one in the kit. 🤪 I have seen people talk about window cleaner to clean the fep and tank. Is that just like regular window cleaner?  Also some have said to use a type of wd40 on the fep to stop it sticking. What would you recommend?

[hendie]

1 minute ago, The Spadgent said:

What would you recommend?

 

I use 70% IPA for cleaning the tank, the build plate, and the parts. I'd rather have just one chemical solution to have to order - I buy it by the gallon now.  I tried Simple Green which seemed to get rave reviews, but to be honest, I find that the 70/30 IPA does everything I need it to.

Personally, I wouldn't use anything on the FEP.  

 

I also bought some soft rubber squeegees to scrape the tank out when finished. This allows you to get most of the resin out of the tank and doesn't scratch the FEP in the process.  Those aren't the exact ones I bought and I can't remember where I got them but I'm sure I got a pack of 10 for less than $10

 

 

[The Spadgent]

16 minutes ago, hendie said:

 

I use 70% IPA for cleaning the tank, the build plate, and the parts. I'd rather have just one chemical solution to have to order - I buy it by the gallon now.  I tried Simple Green which seemed to get rave reviews, but to be honest, I find that the 70/30 IPA does everything I need it to.

Personally, I wouldn't use anything on the FEP.  

 

I also bought some soft rubber squeegees to scrape the tank out when finished. This allows you to get most of the resin out of the tank and doesn't scratch the FEP in the process.  Those aren't the exact ones I bought and I can't remember where I got them but I'm sure I got a pack of 10 for less than $10

 

 

Thanks. You’re being a great help.  Items procured. 😇

[hendie]

51 minutes ago, The Spadgent said:

Items procured.

 

I can't remember if Tony or I have mentioned this, but you probably also want to get hold of Photon Validator (freeware).  It's a great tool for the beginner - you can take you slice file from Chitubox and have it run through the Validator.  The Validator checks each slice layer and can spot 'islands' that may result in a failed print, and it also has some build in optimization tools.  I found it invaluable when I first started and it helped a lot. 

I don't use it anymore as once you've done a few prints, you start to get a feel for how things are going to print and where supports are required. Likewise in Chitubox I don't use the auto-support function at all now.  I always add supports manually and haven't had any issues.  Like everything, it all comes with experience.  Looking at a part and visualising how each layer is constructed, recognising where supports are needed becomes a lot easier once you've done it a few times.

 

I invested in a spare build plate thinking that it may speed things up when I'm doing multiple print jobs, but to be honest, I can remove parts, clean and level the build plate, and be back up and running in less than 5 minutes. It'll come in handy if I ever damage the original though.  One thing I do is level the build plate prior to every print job.  I'm not sure it's needed but it takes less than a minute I'd rather give up a minute than have a failed print job. 

I also bought a couple of spare resin vats.  The most time consuming part for me is changing out the FEP film - it's not difficult, it just takes a little bit of time, so having 3 resin vats on hand is useful. When the FEP needs changed, I can just swap out the vat, and I wait until I've got two vats that need the film changed before I do the job as it doesn't take that much longer to do two at the same time.

 

 

[ICMF]

4 hours ago, The Spadgent said:

One thing I would say though they were hard to get off the plate. I saw a guy on YouTube rock a Stanley blade under one edge then use the spatula so I did that. It worked but Twas a bit hard. 

 I use an artist's palette knife.  Razor thin and highly flexible, so you can get under the part with zero deformation or damage (unlike most putty knife style scrapers) and no chance of damaging the build plate, either.

 

[The Spadgent]

6 hours ago, hendie said:

 

I can't remember if Tony or I have mentioned this, but you probably also want to get hold of Photon Validator (freeware).  It's a great tool for the beginner - you can take you slice file from Chitubox and have it run through the Validator.  The Validator checks each slice layer and can spot 'islands' that may result in a failed print, and it also has some build in optimization tools.  I found it invaluable when I first started and it helped a lot. 

I don't use it anymore as once you've done a few prints, you start to get a feel for how things are going to print and where supports are required. Likewise in Chitubox I don't use the auto-support function at all now.  I always add supports manually and haven't had any issues.  Like everything, it all comes with experience.  Looking at a part and visualising how each layer is constructed, recognising where supports are needed becomes a lot easier once you've done it a few times.

 

I invested in a spare build plate thinking that it may speed things up when I'm doing multiple print jobs, but to be honest, I can remove parts, clean and level the build plate, and be back up and running in less than 5 minutes. It'll come in handy if I ever damage the original though.  One thing I do is level the build plate prior to every print job.  I'm not sure it's needed but it takes less than a minute I'd rather give up a minute than have a failed print job. 

I also bought a couple of spare resin vats.  The most time consuming part for me is changing out the FEP film - it's not difficult, it just takes a little bit of time, so having 3 resin vats on hand is useful. When the FEP needs changed, I can just swap out the vat, and I wait until I've got two vats that need the film changed before I do the job as it doesn't take that much longer to do two at the same time.

 

 

Thanks that’s some good advice. I’m now awaiting new tools to get my next journey into modelling underway. It’s odd that even though I kind of do this for a living it’s given me a whole new take on 3D modelling. Different ways of building things aaaand more importantly making stuff for me! I can foresee a lot of sci fi models coming. 😇🙌

[Jo NZ]

Going back to the origins of the thread, any 3D models (and any CAD) should always be drawn FULL SIZE. It's really easy to scale in Chitubox and that's when you do it.

I've just been pulling my hair out printing car bodies where the scale isn't specified - they are drawn at all sorts of odd sizes. Sometime the description helpfully tells you that it can be printed in 1/16th, 1/18th, 1/24th, 1/43rd..... But not what to reduce it by!

So my technique:

Import the stl file into Fusion 360. It should draw the mesh

Check the size using dimension (I usually measure overall length)

Compare it to the full size dimension of the car (some of the models are roughly 1/2 scale, but others are all over the place)

Work out what it needs to be reduced by.... (yes, that means sums😒)

Print it.

 

Why oh why don't the creators of these files draw in full size in the first place. It was the first thing I was taught using 3D CAD in the early 80s - and then we had to set up the workspace, rather than it automatically fitting the workpiece as it does now.

 

Numpties!

[The Spadgent]

On 04/10/2021 at 00:27, Jo NZ said:

Going back to the origins of the thread, any 3D models (and any CAD) should always be drawn FULL SIZE. It's really easy to scale in Chitubox and that's when you do it.

I've just been pulling my hair out printing car bodies where the scale isn't specified - they are drawn at all sorts of odd sizes. Sometime the description helpfully tells you that it can be printed in 1/16th, 1/18th, 1/24th, 1/43rd..... But not what to reduce it by!

So my technique:

Import the stl file into Fusion 360. It should draw the mesh

Check the size using dimension (I usually measure overall length)

Compare it to the full size dimension of the car (some of the models are roughly 1/2 scale, but others are all over the place)

Work out what it needs to be reduced by.... (yes, that means sums😒)

Print it.

 

Why oh why don't the creators of these files draw in full size in the first place. It was the first thing I was taught using 3D CAD in the early 80s - and then we had to set up the workspace, rather than it automatically fitting the workpiece as it does now.

 

Numpties!

Yes that does make sense. Sometimes however finding the actual size of things is harder than finding the size you want to print.  I totally understand what you’re saying though.  I was struggling with how the original rook test print of the Mars was sized 1.4cm I think in diameter but came out about 3cm when printed.  I was loading the .STL into max. Then I found the scene that gets printed, the one with two rooms and that had been scaled up in Chitu box. 🤪 so now I can get my scales right. Big or indeed small. 😇 Thanks for your help. 
 

Johnny.

[Rob G]

On 10/4/2021 at 9:27 AM, Jo NZ said:

 

Why oh why don't the creators of these files draw in full size in the first place. It was the first thing I was taught using 3D CAD in the early 80s - and then we had to set up the workspace, rather than it automatically fitting the workpiece as it does now.

 

Numpties!

They're not numpties, they just don't know any better. The answer is right there in your comment, where you say "It was the first thing I was taught". Most of those using CAD and printing at home haven't been formally schooled in 'the right way' and are either learning via YouTube or making it up as they go along, and are not receiving a sound base for further progress. Hence, we get the confuzzled mess that we see. I'm a photographer, and I see exactly the same thing. 

 

It's one of the downsides of affordable technology, I guess. 

[bootneck]

I agree entirely.  I would have really liked to have been able to afford formal tuition, to sit alongside someone and learn all this in the correct format; however, that isn't going to stop me from continuing with online tutorials and the like.  I did try a 1:1 drawing of my Matador refueller but when I reduced it to 1:144 scale the smaller parts wouldn't print.  I did another drawing, this time to 1:144 scale and everything printed fine.

 

On 04/10/2021 at 00:27, Jo NZ said:

Why oh why don't the creators of these files draw in full size in the first place. It was the first thing I was taught using 3D CAD in the early 80s - and then we had to set up the workspace, rather than it automatically fitting the workpiece as it does now.

 

Numpties!

As for being called a Numpty for not drawing to full size, at least I am drawing them myself and not downloading other's work; and then blaming them for it.

 

Mike