Hard-to-get parts and 3D printing

[monkeyman]

Hi All,

Based on a post (and photobucket photos) by Mike (Zedback) I decided to replace the door locks, petrol cap lock, and hatch lock on my Z. There were some issues with this, but they are not the purpose of this post. The hatch lock looked tricky, but with some words of encouragement from Mike, I had a go at it.

See here for his photos

http://www.viczcar.com/forum/index.php/topic,3987.msg92189.html#msg92189

 

The hatch lock was fiddly, but it went to plan, except that I found the lock casing to be worn.

Without a key inserted (or a wrong key), the pins (or wafers) protrude from the central cylinder (the lug). The lug won’t turn in its casing as the wafers extend into grooves in the lock casing that inhibit its rotation. With the correct key inserted, the wafers are pulled flush with the surface of the lug, and the lug can rotate.

My problem was that the edges of the grooves were worn where the wafers slid over the edges. The edges were rounded. So the wafers didn’t have to be flush, and the wrong key could still open the lock (see attached picture.. I haven't worked out how to put the photos in the post yet)

 

Could I get a new one? I didn't even bother trying.

Second hand? Bought one off Gumtree, hoping that maybe it would be good. It was worse. They're all 40 years old. Forget second hand.

Get one machined? I took it to a local machine shop. They didn't want to know about it. Too fiddly. And it would cost a bit because there was a lot of work in it (there is more detail than you can see in the photo).

So, I got one printed!

I downloaded some free 3D printing software off the internet called 123D Design.

With my limited drawing experience I was able to work out how to use it, and create a 3D design for my lock enclosure in one evening. It isn't very sophisticated or powerful, but that might be why I was able to pick it up quickly. I found it crashed often on my laptop, so if you try it out, save regularly (and if you are using Windows XP, don't bother.. it won't work).

 

I later made some small adjustments to my design to meet some requirements for the 3D printing, and the design ended up looking like the attached pics.

 

I will post the results of the printing in the next post. Stay tuned.

Eric

[monkeyman]

So,

The impressive thing is that 3D printers don't just print in plastic.

I uploaded my design to the 123D Design website, and they directed me to a number of 3D printing houses. I used Shapeways. Another printer (i.materialise) had more materials that could be printed, but Shapeways had cheaper shipping to Australia. I looked at three options given that it would have to be strong and handle weather: Brass, Stainless Steel, and Titanium (yep, that's right!). To have this made in Brass was about AU$45, in Stainless steel around $130 and Titanium around $240 (if I remember correctly). I went for brass (and I got a plastic one printed for under $5 so I could show people). The shipping was a flat rate $20 to Australia.

So for about $65 I got myself a new hatch lock casing.

I had to sand inside a little as it was a bit too tight, and then I dropped it off at the chrome-platers (who are also doing my bumper bars).

 

So if you can't get the part you want, think about printing it! (if you are interested, start by Googling the 123D Design and the printing companies above, and there was another printing company on the 123D design website called ‘sculpteo’)

 

Eric

[luvemfast]

Will be ineteresting to see progress with this.

I'm only just getting into 3D printing, so will follow closely.

[zedevan]

There's lots of tutorials online and software such as solidworks is pretty self explainatory for block modeling things. If anyone ever wants something more complicated 3d modeled I'd be happy to help out.

 

The metal printers are pretty awesome, but your typical parts are fairly brittle and only really good for testing if geometry is correct, and then using them to make silicon molds for vacuum casting 'real' plastic or polyurethane parts. The main advantage of the printers is the ability to make things you can't traditionally machine or tool.

 

For those prices you could have likely had the parts machined out of the material in china

 

source: I'm a product design engineer/CAD monkey

 

 

[monkeyman]

The metal printers are pretty awesome, but your typical parts are fairly brittle and only really good for testing if geometry is correct, and then using them to make silicon molds for vacuum casting 'real' plastic or polyurethane parts. The main advantage of the printers is the ability to make things you can't traditionally machine or tool.

 

As I was looking at the printing websites, I found that some metals were printed directly (such as stainless steel), and some were made from a mold (as you mentioned). Brass is one of those made from a mold. The 3D printer prints in wax, then a mold is formed from the wax model. The wax is melted out and the brass is poured in. So the brass should be as strong as any cast item.... I hope.

[zedevan]

Yep should be as good as a die-cast part for general purposes, as the runner and vent design is only roughly estimated so can end up with some voids etc. I had my wife's engagement ring cast from platinum using a lossless wax 3d printed model, and they wouldn't guarentee that pockets of air woudln't be exposed during the polishing process.

 

I've only played around with direct printed titaniums, the company selling the machine was was giving out bottle openers made with a honeycomb structure. Apparently the US aircraft carriers use them to print spare parts as required so they dont have to drive around with them, but then replace it with real parts once they arrive from where ever.