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Dear Friends, I have started with 3D printing and already found a very handy project where the designing and printing really did a great job to solve the problem with Atlas underbody bolsters always being a mess. That's clearly the down side of multi-gauge manufacturing that you always need enough clearance for the 3-rail fraction.

My Prusa i3Mk3 was surely quite an investment and to build it up from parts a challenge. It runs surprisingly well and the filament forms super strong parts.

I've designed the part in Autodesk Fusion 360 after watching some tutorials on YouTube. The software is free for private use.

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The amazing thing is how exact the measurements are (0.1mm).

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Here's the finished frame with shims between bolster and draft gear box. I incorporated these into a next version of the part.

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I am a big time fan of Jay Criswell's cast proto:48 conversion bolsters to re-use your old IM truck parts. The wheels are NWSL.

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The print is so exact that you can easily achieve a perfect fit of that trucks, they glide on these little pads and ensure an upright car body.

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You might have seen some stepping in the filament print. That's clearly there but could be sanded easily. I did not because you can't see what's going on under that truck from no angle.

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This boxcar conversion was a real learning challenge but now I have the file to print these as needed. More cars are waiting in the basement.

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Greetings from Austria

Sarah

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"Look at the resin printers as they can print with higher resolution."

Yes, and no. Resin printers will indeed print at a higher resolution, but there are lots of things that you make for which resin is not as good an alternative as the FDM printers and for which you don't NEED a high rez for.  The things that she is making is a good example, quick and easy print, made out of strong plastic. Resin printers are frankly, a pain in the ***. They are great for some things, no doubt, but it is sort of like cooking. You pour the liquid in the vat, don't breathe it if you can help it, then you start your print. IF all goes well, you then open the machine and have a dripping wet item and whatever liquid is left over in the vat. You take the plate off the machine that your print is stuck to and either get your rubber gloves on and take it off the build plate or else leave it attached and open up your Iso alcohol and swish the item around in it for 5 minutes or so. Then you blow off the excess with an air hose and rewash it in soapy water. Then, still wearing gloves so you don't get it on your skin, you have to set it with UV light. This is usually best down while your part is submerged in water, so you need a glass container large enough to hold whatever you print.  Oh yea, you have to remove the item at some point from the build plate. It will be stuck pretty good, sometimes you ruin your part unsticking it. Anyway, once the UV light has cured the part, you can safely touch it now with your bare hands. But don't let the cat or dog chew on it, it is still toxic. Now, if you cured it while in water, it probably has not warped any. Otherwise, you got to decide if slight warping matters.  Let it sit for a week and it may warp more, you just never know. Oh, and while you are waiting, you need to get a bottle and run the left over liquid in the vat through a very fine filter.  You NEVER put used resin back into the virgin resin bottle. And you can dunk you vat into your alchy and clean it too after draining it.

OR, you can buy a roll of plastic of whatever kind you want to use, print it on the FDM printer and it is ready to use, no washing, curing, blah, blah, blah. Whoops, you say the dog got ahold of it and chewed it, no problem, dog will be fine, just print a new one...

Resin printers are frankly, a pain in the ***.

not if you have a nice one like a FormLabs3 that auto-fills the tank and has resin cartridges. I rarely have an issue with my prints.

also resin prints are isotropic meaning strong in all directions. FDM or rather tube printers print objects that are inherently weak in the Z-direction. Warping rarely occurs if your print is properly designed. Certain resins used by dentists is not toxic.

Last edited by AlanRail

Other companies are catching up with Formlabs.  Elegoo Jupiter launches tomorrow.  Unlike Formlabs it uses a built plate to keep costs down.  They will have a build volume compatible build volumes and resolutions (10.9" x 6.6" x 11.8" and 0.002" respectively) .

I don't have any experience with the water soluble resins so I can't comment on the smell or toxicity.

Jan

Before you spend 15-20 times more on a Form Labs, do some research.  The resin for these are 3-4 time more than for most of the cheaper ones, but a bigger problem seems to be poor customer service and slow shipment of supplies.   They could be easier to use, more bells and whistles, and less tweaking needed for good prints, but a side by side comparison of prints with the $200 printer I use,  will show no difference.

@AlanRail posted:

Resin printers are frankly, a pain in the ***.

not if you have a nice one like a FormLabs3 that auto-fills the tank and has resin cartridges. I rarely have an issue with my prints.

also resin prints are isotropic meaning strong in all directions. FDM or rather tube printers print objects that are inherently weak in the Z-direction. Warping rarely occurs if your print is properly designed. Certain resins used by dentists is not toxic.

Aren't resin printers old technology?  My brother did his aerospace engineering master's thesis using resin printing technology in 1996.

So is FDM printing.  It is the engineering that goes into the printers.  The low-cost resin printers use LCD panels like in your TV and phone to mask each layer.  Mono LCD panels are used now instead of color which results in faster printing and longer panel life.  An array of UV LEDs instead of scanning lasers set the resin.  That's why you can get a small printer for under $200.  The build area is limited by the size of the LCD panel.

Mechanical techniques like the traveling laser in the Formlabs printers make for a larger build area.

The resolutions of the printers in comparable.i

Jan

Got a new design: I'm experimenting with getting a Union Pacific O-50-6 tank car printed and by now I feel up to designing the model. Fusion 360 is really very intuitive and with some tutorials it turns more and more into a handy tool for modelling bigger projects. The turret's rivet rows were really tricky, though.

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@Jan posted:

Other companies are catching up with Formlabs.  Elegoo Jupiter launches tomorrow.  Unlike Formlabs it uses a built plate to keep costs down.  They will have a build volume compatible build volumes and resolutions (10.9" x 6.6" x 11.8" and 0.002" respectively) .

I don't have any experience with the water soluble resins so I can't comment on the smell or toxicity.

Jan

I've got an order in for a Jupiter ($600 kickstarter price). Hate having to wait until early next year for it to ship, but the price can't be beat, and the self-refilling vat is especially great for large items (as is the extendable Z axis modules). Currently have a Qidi Shadow 5.5s, works great, but the small build size really limits its usability to detail parts for the most part.

I exclusively use water washable resin (have a bottle of the regular stuff lying around, but alcohol was ridiculously hard to come by during the beginning of the pandemic). It's not as versatile, as most tend to be rather fragile when cured, but the ease of cleanup makes it worthwhile for most of the stuff I print.

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