MadModder

The Shop => Metal Stuff => Topic started by: RotarySMP on May 10, 2020, 07:24:00 AM

Title: Lost PLA bronze casting of the Beatles - Abbey Road
Post by: RotarySMP on May 10, 2020, 07:24:00 AM
Hi Madmodders,

I took a week off my mini-lathe project to cast a statue for my Beatles fan wife...

My Lost PLA technique is pretty rough. I need to watch more of Jeff the veg oil guys videos, and sort out the details, but it was well received, even with defects.

I made a video of the whole thing here:

Title: Re: Lost PLA bronze casting of John Lennon
Post by: Joules on May 10, 2020, 08:19:23 AM
These must be the Yuk, Oh No prints....

10 out of 10 for the volcano model.

Mark, when you need to join PLA parts for casting, consider welding them using a very fine tipped temperature controlled iron.  I use the same tool I used to use for waxing when we did lost wax castin, do it like Tig welding using some filament as filler rod, you can then work the PLA back to blend in.  Likewise never use a pigmented PLA always use natural, no residue left behind and you can easily see your welds using a bright light behind the model.
Title: Re: Lost PLA bronze casting of John Lennon
Post by: RotarySMP on May 10, 2020, 08:57:57 AM
Thanks a lot for the advice. I didn't even think about welding it.  :doh:

That oil burner is a bit of a temperamental beast. The home made needle valve is not perfectly concentric, so it goes low-high-low-chernobyl! A little too much, and it is like one of those tractor drag racers.

Have you ever tried spraying the part with clear coat to smooth it? I saw it in this video,

 and was wondering of you know if there is anything special to look for, or just cheap rattle can?

I'll buy some more clear filament.

We went to the Yoko Ono exhibition in Krems a couple of years ago. Her art doesn't work for me. at all.
Mark
Title: Re: Lost PLA bronze casting of John Lennon
Post by: Joules on May 10, 2020, 10:37:37 AM
Can't help with advice on coating prints for casting.  I have used sanding sealer for some commercial pieces and then wet sanded them.  For casting I would be tempted to just wet sand the PLA, time consuming but you get out what you put in.  I did change to a 0.3mm nozzle a few years ago and get much better quality prints, less work needed to get a good surface finish.  You do pay a penalty in print time, wish I still had contacts for casting these are interesting times.
Title: Re: Lost PLA bronze casting of John Lennon
Post by: RotarySMP on May 10, 2020, 01:50:44 PM
Good point. I am still on a 0.4 nozzle, and printed with 0.2 layer height.
Title: Re: Lost PLA bronze casting of John Lennon
Post by: efrench on May 10, 2020, 03:09:27 PM
I have a .3 nozzle and use a .07mm layer height for most things.
Title: Re: Lost PLA bronze casting of John Lennon
Post by: RotarySMP on May 11, 2020, 02:54:15 AM
The prints must take forever dont they?
Title: Re: Lost PLA bronze casting of John Lennon
Post by: Joules on May 11, 2020, 06:18:30 AM
I print at 0.1mm, so they take about twice as long as 0.2mm   Time generally isnít an issue as I leave the machine running whilst doing other work.  My machines are pretty well dialled in and very rarely have failed prints (use support for prints)  For a long print I will get up early, set the job running, and hopefully be finished before going to bed.  If a large print, I will do it in sections over a few days and weld the parts together.

You can print smart by having voids inside a large print and only mesh between thin inner and thicker outer shell, making a stiff print that doesnít use as much material or time.
Title: Re: Lost PLA bronze casting of John Lennon
Post by: RotarySMP on May 12, 2020, 01:46:40 PM
Smart use of voids is a good idea. Thanks.
Title: Re: Lost PLA bronze casting of the Beatles - Abbey road
Post by: RotarySMP on December 27, 2020, 12:17:45 PM
Time to try another Beatles statue... This is the summary of my efforts over the last two weeks.


Mark
Title: Re: Lost PLA bronze casting of John Lennon
Post by: Bee on January 04, 2021, 04:15:51 PM
Great video Mark. Like the ideas and what can be learned from your problems. Like the silicone seal for the vacuum.
Title: Re: Lost PLA bronze casting of John Lennon
Post by: RotarySMP on January 05, 2021, 06:54:43 AM
Thanks. Once the Covid lock down is over, and I can get some materials and borrow my mates vacuum pump, I'll have another go at casting it.
Title: Re: Lost PLA bronze casting of Georg Harrison
Post by: RotarySMP on May 30, 2021, 06:58:27 AM
I have tried to address the worst errors I made in that last attempt. The most important improvements were to:
1/ Make a burn out oven.


2/ get a statinless tube as a flask.
3/ borrow a vacuum pump.
4/ wait till the bronze was hot enough.

So I made some progress...