3D printing for 7mm

AndyH

Active Member
Hello,

I have commented a few times upon the subject of 3D printing so I thought it was about time I showed examples of what I am trying to do.

The following are photos of a 7mm GWR spark arrester, using information from the original 1935 Swindon drawing number 105119, modelled in Fusion 360 (full scale), and printed at 0.025mm layer height on a Form 2 printer. The support touchpoint width was also modified from the default thickness so as not to obscure detail or cause breakages upon removal.

The model is a JLTRT 57xx, which will be a Truro engine, most likely 5744.

The aim was for it to run in two versions, with the dustbin, and without. Though photographs show the chimney being shorter than the original drawings.

The parts need an ultrasonic clean, and some cruel close ups.

I used clear resin as it was all I had left over from a project.

There was an issue with the upper seam due to the angle of the build. I will thicken the part to try and offset any issues. This is part of the challenge in balancing scale accuracy and the limitations of the device

The nuts are perhaps over-scale in terms of those selected, but I wanted them to be visible and they met the size on the drawing.

I aim to investment cast a version when and if I make time.

Hope this is of some interest.

Andy
edited for late night typos

IMG_7269.JPG IMG_7276 2.JPG IMG_7277.JPG IMG_7274.JPG IMG_7276.JPG
 
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paratom

Western Thunderer
The parts don’t look too bad but why did you need to put them in an ultrasonic cleaner afterwards. I clean my parts with isopropanol or water if I am using a washable resin. I’m finding the washable resins quite good and makes cleaning up so much easier afterwards.
 

AndyH

Active Member
Because of the debris in the workshop, you can see when you zoom in. IPA is the first wash straight after printing and before curing, but still slightly tacky after curing (yes using formlabs station and curing times), and then this is when it collected extra dirt.
I reprinted anyway, and added a seam at the front and changed a few other parts.
 

AndyH

Active Member
Yep, thanks for the advice. Good point.

We have four formlabs printers so get through a lot of IPA, and as this isn’t a priority so using the ‘spare’ after jobs is okay. This part isn’t the business, only a hobby :)
 

michael080

Western Thunderer
I am using the formlabs washing station as well and noticed the problem with sticky parts after washing. It helps to flush the parts after washing with a small volume of IPA from a lab washing bottle. (see example below). Doing that over the washing station flushes the liquid into the main reservoir, so that no IPA is wasted.

s-l1600.png

Did you also notice that a lot of IPA evaporates from these washing stations? Quite annoying.

Michael
 

paratom

Western Thunderer
If I'm not using washable resin I put my isopropanol in a cheap airbrush like the Humbrol one and give the items a good blast while they are still on the build plate before removing them to soak in some isoproponol for a couple of minutes.
 

Overseer

Western Thunderer
If I'm not using washable resin I put my isopropanol in a cheap airbrush like the Humbrol one and give the items a good blast while they are still on the build plate before removing them to soak in some isoproponol for a couple of minutes.
Isn't this dangerous? Spraying IPA could easily create an explosive mixture with a low flash point. Also it will increase the exposure to IPA, worth checking the symptoms of absorbing higher levels of IPA.
 

simond

Western Thunderer
Wikipedia tells you all you need to know, flammable between 2 & 12% concentration, and a flash point of 12C.

and the toxicology can be summed up by it’s discontinued use as a veterinary anaesthetic, a long time ago.
 

AndyH

Active Member
For reference I use IPA in a safelab extraction cabinet with carbon filters, where our cleaning tanks sit, we do use lab wash bottles, and have a flam safe bin. Even though we use large volumes of IPA our COSHH control measures are pretty tight. The disposal of used IPA is worth looking at too. I’ll spare you the PPE side.
Ahem, moving away from IPA, I’d be interested to see the other small scale detail prints of others.
 

neaston

Western Thunderer
In my 40+ years working as a veterinary surgeon I never heard of the use of IPA as an anaesthetic agent even in the distant past.
Ethanol, preferably in the form of a good malt, was a good relaxant at the end of the day.

Nick
Ps Inebriation of laboratory animals which is what is described on Wikipedia is NOT anaesthetising.
 
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paratom

Western Thunderer
Isn't this dangerous? Spraying IPA could easily create an explosive mixture with a low flash point. Also it will increase the exposure to IPA, worth checking the symptoms of absorbing higher levels of IPA.
You got me thinking about the spraying aspect of IPA as I never thought this was dangerous. It turns out you can buy IPA in a spray bottle on Amazon so my conclusion is it can't be that dangerous providing you wear a mask.
 

simond

Western Thunderer
Nick,

I was merely summarising this;

“Although isopropyl alcohol can be used for anesthesia, its many negative attributes or drawbacks prohibit this use. Isopropyl alcohol can also be used similarly to either as a solvent[23] or as an anesthetic by inhaling the fumes or orally. Early uses included using the solvent as general anesthetic for small mammals[24] and rodents by scientists and some veterinarians. However, it was soon discontinued, as many complications arose, including respiratory irritation, internal bleeding, and visual and hearing problems. In rare cases, respiratory failure leading to death in animals was observed.”

and suggesting it’s probably not great to breathe lots of the stuff…
 

Arun Sharma

Western Thunderer
Nick,

I was merely summarising this;

“Although isopropyl alcohol can be used for anesthesia, its many negative attributes or drawbacks prohibit this use. Isopropyl alcohol can also be used similarly to either as a solvent[23] or as an anesthetic by inhaling the fumes or orally. Early uses included using the solvent as general anesthetic for small mammals[24] and rodents by scientists and some veterinarians. However, it was soon discontinued, as many complications arose, including respiratory irritation, internal bleeding, and visual and hearing problems. In rare cases, respiratory failure leading to death in animals was observed.”

and suggesting it’s probably not great to breathe lots of the stuff…
Simon - Did you mean 'either' or 'ether' - Ether has long been used as an anaesthetic and is especially safe in obstetric use - though has other disadvantages such as its flammability.
 

simond

Western Thunderer
Hi Arun,

I just copy-pasted Wikipedia! I didn’t see the slightly odd phrasing which could mean a typo til you pointed it out.

It does seem to indicate the earlier use of isopropanol as an anaesthetic, nonetheless.
 

paratom

Western Thunderer
Having read all the replies I have come to the conclusion that IPA is safe to spray proving your not breathing it in or near a naked flame. I had thought about trying it in my cheap ultrasound cleaner but the Darwin Awards came to mind and I refrained from doing so.
 

JimG

Western Thunderer
Having read all the replies I have come to the conclusion that IPA is safe to spray proving your not breathing it in or near a naked flame. I had thought about trying it in my cheap ultrasound cleaner but the Darwin Awards came to mind and I refrained from doing so.

I use IPA in my small ultrasonic cleaner but I now put water in the cleaner's tank and the IPA in a plastic yogurt pot which is sat in the water. Previously I had the IPA in the cleaner's tank but the resin residue built up in the tank and the parts were effectively coated with a light covering of resin when removed from the tank. Cleaning the tank became an expensive operation, especially at the start of the pandemic when the price of IPA rocketed. So I started using the IPA in yogurt pots which works just as well and I can control the resin residue by decanting carefully between pots when the resin has settled to the bottom. It does restrict the size of part I can cope with but so far I haven't been printing anything which doesn't fit in the pots.

Jim.
 

adrian

Flying Squad
Simon - Did you mean 'either' or 'ether' - Ether has long been used as an anaesthetic and is especially safe in obstetric use - though has other disadvantages such as its flammability.
Reminds me of school! In the dim and distant past at Comprehensive school we were in Chemistry class, when the Physics teacher came in to "borrow" a volatile liquid for a physics demonstration. He wanted to demonstrate the latent heat of evaporation to his physics class. The idea being that you get a small square block of wood, a cover with a thin film of water. Placed on which is a glass beaker of volatile liquid. To encourage evaporation the kids were to blow through a straw into the liquid - the heat absorbed to evaporate should be sufficient to freeze the glass beaker to the wooden block.

Yes you guessed it, he used ether for the experiment, needless to say there were quite a few woozy students staggering out of the class room after 10 minutes or so!!
 
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