How do I remove the first layer of a model to make the second layer the start of a print?
 
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How do I remove the first layer of a model to make the second layer the start of a print?  

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BoilermakerFan
(@boilermakerfan)
Active Member
How do I remove the first layer of a model to make the second layer the start of a print?

I have a model of a goat that I grabbed off Thingiverse. The problem is when I scale it up in size to make it large enough to print reliably, it slices weird and it starts only the back legs in the first layer which causes a print to fail.

Here is the link to the model: https://www.thingiverse.com/thing:588222

The largest I could scale it up was 300% with the first layer staying correct, but the legs are too tiny at 300% and it falls over even with glue stick on a clean bed.

I need to scale it up to 600% to get a decent size print, but anything over 400% it skips the front legs on the first layer.

I have a Prusa MK2 and I have the print setting at 0.15mm Optimal.

I think that if I could just slice and export the g-code of the 600% scaled model, then remove the G-code for the first layer and shift everything down so the sliced second layer becomes the first layer, everything would print correctly.

Thanks for any guidance you can share,

BoilermakerFan

Postato : 23/03/2018 9:42 pm
Nikolai
(@nikolai)
Noble Member
Re: How do I remove the first layer of a model to make the second layer the start of a print?

I would use brim for this model and make sure your first layer is perfect.
You could also lower the model by couple mm in Z direction in your slicer to get a little bit more surface on the feet.

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Postato : 24/03/2018 12:28 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: How do I remove the first layer of a model to make the second layer the start of a print?

in Slic3r, load the model,
scale to 600%
slice and look at your bottom layer. as advised only two hooves show small contact patches
highlight the model in 3d view, so it goes green, select the cut button
set the cut height at 0.2mm, unclick the keep lower part check box, then click the perform cut button, and your change is made...
re slice, and print...

the legs are quite tall, the feet are quite small, and the underbelly/neck/chin are unsupported so you are going to need supports, even then, the extruder may knock a leg over before the print joins them with body...

a raft or brim may make the print more successful

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Postato : 24/03/2018 1:02 am
BoilermakerFan
(@boilermakerfan)
Active Member
Topic starter answered:
Re: How do I remove the first layer of a model to make the second layer the start of a print?


in Slic3r, load the model,
scale to 600%
slice and look at your bottom layer. as advised only two hooves show small contact patches
highlight the model in 3d view, so it goes green, select the cut button
set the cut height at 0.2mm, unclick the keep lower part check box, then click the perform cut button, and your change is made...
re slice, and print...

the legs are quite tall, the feet are quite small, and the underbelly/neck/chin are unsupported so you are going to need supports, even then, the extruder may knock a leg over before the print joins them with body...

a raft or brim may make the print more successful

regards Joan

Thank you Joan!

That is exactly what I was trying to figure out how to do.

The extruder didn't knock over the leg, it just fell over because it was so small and didn't have enough area to bond to the bed.

I'll try adding a brim in addition to the supports.

My son and I love goats and that model was just so cool it's been driving me crazy that I couldn't get it to print.

Cheers!

- BMF

Postato : 24/03/2018 8:38 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: How do I remove the first layer of a model to make the second layer the start of a print?

Hi BMF, please put a picture of it, on here when it's printed
regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Postato : 24/03/2018 12:48 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: How do I remove the first layer of a model to make the second layer the start of a print?

I had a go...

[attachment=0]20180324_173412[1].jpg[/attachment]

mine came out like this...

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Postato : 24/03/2018 6:35 pm
BoilermakerFan
(@boilermakerfan)
Active Member
Topic starter answered:
Re: How do I remove the first layer of a model to make the second layer the start of a print?

Nice! Did you use supports?

I'm getting ready to mod the file then get it started.

Postato : 24/03/2018 11:03 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: How do I remove the first layer of a model to make the second layer the start of a print?

Hi BMF, Yes I did use Supports

they came off reasonably easily..
I didn't have to do any clean up...

Unfortunately the rear left leg fell over whilst I wasn't watching... so it's a bit of a Wonkey Donkey!

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Postato : 24/03/2018 11:46 pm
BoilermakerFan
(@boilermakerfan)
Active Member
Topic starter answered:
Re: How do I remove the first layer of a model to make the second layer the start of a print?


Hi BMF, Yes I did use Supports

they came off reasonably easily..
I didn't have to do any clean up...

Unfortunately the rear left leg fell over whilst I wasn't watching... so it's a bit of a Wonkey Donkey!

regards Joan

LOL! Poor goat!

I printed my 600% scale version on a 5mm brim setting w/o supports. I wasn't too concerned if it failed, I just wanted to see if the legs would stay secured. They did and the belly had some strings and a section of one layer peeled out, but it ended up finishing much better than I thought it would. I just used side snips and a X-acto blade to clean up the belly. The model was still smaller than I want it to be too, so I'm going to scale it up more and probably put it on a raft. I wonder if going up to 1800% will make the bridging along the belly easier or worse since the layer height will be staying at 0.15mm?

Anyway, my son was happy with the first successful result after weeks of failures, so that's a great thing. He didn't even ask for a reprint, I just told him I wanted to make two more that are bigger. One for him and one for me.

Thank you so much for the help. I knew what I wanted to do was possible and would work, I just had no idea how to do it. Now I have to correct a scaled up sea otter for my wife!

I'll get the pics uploaded tomorrow.

- BMF

Postato : 25/03/2018 8:22 am
BoilermakerFan
(@boilermakerfan)
Active Member
Topic starter answered:
Re: How do I remove the first layer of a model to make the second layer the start of a print?

Here's mine printed at 0.15mm Optimal without supports, 5mm brim. I will be scaling it up more and printing it again, but with supports.

Postato : 26/03/2018 4:42 pm
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