“It Came From Within The Brown Truck” - Now In 3D!!

[sshire]

“It Came From Within The Brown Truck” - Now In 3D!!

Through the fog I spot Richie, my UPS guy, hauling this large box down the driveway. After commenting that the boxes from Speedy Metals and Enco are more manageable, he faded away, back into the fog.

3D printer!!



It’s a DaVinci 1.0. 8”x8”x8” heated build platform; completely enclosed; very nicely put together. All wiring bundled and routed correctly; electronics enclosed; real 120V power cord instead of a crappy wall wart; filament spool contained inside the case. All In all, quite nice for $450.00.







I had pre-ordered the new Solidoodle Press months ago. An absolutely, drop dead guaranteed pre-Xmas delivery date. Then, email and blog posts came at irregular intervals; “Should be there on time”, “Well, might be a slight delay”, “Oh, did we say instead of building them in Brooklyn (as with all of their previous printers) we found a very nice factory in China?”, “Working out some production glitches in China”, “First batch of 200 is done and tested. Shipping next week”, “Based on your order number, looking at delivery Mid-February”, yada yada.

I cancelled the order and after much research, ordered the DaVinci at Amazon. Two days later, here comes Richie through the fog. Better.

After living with it for about a month now, here’s what I know.

Packed beautifully. More foam than the neighborhood pub on a Saturday night. All cables, manuals, DVD, etc. in little die cut areas of the top packing.

Setup took about 15 minutes. The critical issue with 3D printers is the bed leveling. The printer has a built in program to help with this. After bouncing around and minutely adjusting the three leveling knobs (nicely knurled, BTW) for about 30 minutes, I went down to the shop and grabbed the feeler gauges. Based on the recommendations for the extruder to bed gap, I manually adjusted at a number of points for a slip fit of the feeler gauge. Total time: 5 minutes. Done.

Either draw the part in Inventor or Solidworks or Sketchup, etc. and export the .STL file. Then, open the STL file in DaVinci’s slicing software (they’ve licensed Slic3r and put a much simpler interface on it) and click on “Print.” That’s it.

So, after printing the obligatory Nautilus gears and the twisted vase, I figured that a good learning exercise for me in Inventor (I’m just starting to get a handle on it) would be something that everyone needs: a personalized end mill pencil holder.







Now I wanted something that would show movement. A 3D printed version of mechanism #123 in the “507 movements” book. I downloaded the .stl files from Thingiverse.com.

I gang printed everything but the base and rack. Other than “deburring”, everything was either a slip fit or a press fit. Too easy. The fan gears and driving gears are attached with 4-40 BHCS.













 Next, I’ll assemble this two cylinder, rocker. No hardware. All threading is done in the print.



Here’s a bit of the action on the rack.

<a href="https://www.youtube.com/watch?v=7yvig7eE8Ec" target="_blank">http://www.youtube.com/watch?v=7yvig7eE8Ec</a>

<a href="https://www.youtube.com/watch?v=gas85hPhNOc" target="_blank">http://www.youtube.com/watch?v=gas85hPhNOc</a>

[b.lindsey]

They are amazing machines Stan, and unbelievable how the price has come down even over the last year or so. You should have a blast with it and will no doubts find all sorts of useful things to make with it as well.  I particularly like the end mill (or is that a slot drill ) pencil holder. May have to make myself one of those here at work.

Bill

[90LX_Notch]

Stan-

Very cool.  3D printing is fascinating.  How durable are the printed items?  Are they brittle or are they "flexible" like ABS plastic?

-Bob

[Kim]

Merry Christmas Stan
That's pretty cool!  I love the reciprocating rack!
Kim

[Brian Rupnow]

Truly amazing stuff!!! Congratulations.---Brian

[sshire]

Bill
It's so similar to anything that gains traction. More units=lower cost.
Computers, cameras, television, etc.
I've actually printed some useful things. A wall mount for the drip irrigation timer/filter unit (which awaits the return of Spring.) A replacement for a broken beach chair part (the original was ABS also), a car mount for the iPhone (the clip broke on the original) and a stand for the ball end mills and roundovers.

Bob
I'm printing with ABS. Depending on how much infill I specify (10%-100%) the piece can be tailored for expected usage.

[90LX_Notch]

Wow Stan that is impressive.  One can really make some neat projects with this.  I assume that the ABS, when printed, would not be as strong as it would be when injection molded, but should still be quite strong.

-Bob

[philjoe5]

Nice work Stan.  That's pretty impressive stuff from a $500 machine.

I guess great minds think alike  because I'm working on Cartwright's mechanism for parallel motion, #328 in Brown's book.  I'm doing it in the metal stuff.



I may tackle the #123 at some point

Cheers,
Phil

[sshire]

Bob
Having absolutely no knowledge at this point, wouldn't 100% ABS infill be similar to injection molded ABS. The only thing that might make the printed part weaker is the layering process. If each layer is not fully fused to the last one, it would be weaker in shear. Injection molding is a contiguous mass of ABS.
However, unless you need many, many parts in a short time, 3D wins for prototyping as the cost of the tool is eliminated.

I certainly wouldn't trust my life to one of my 3D printed parts.

I'm hoping someone out there can shed some light on this whole strength thing.

[sshire]

Phil
That is really nice! I'm looking at more from the book to practice my Inventor skills. With the FarmBoy going on, I don't need another metal project. This way, I can send a part to the printer and then go down to the shop and screw up another part on the engine.

[90LX_Notch]

Stan-

If I didn't need a better lathe so bad I would order one of these. I hope someone with knowledge pipes in about the strength.  I find this very interesting.  The possibilities for repairs, tinkering, etc. using one of these are mind blowing.

-Bob

[Dave Otto]

Bob
Having absolutely no knowledge at this point, wouldn't 100% ABS infill be similar to injection molded ABS. The only thing that might make the printed part weaker is the layering process. If each layer is not fully fused to the last one, it would be weaker in shear. Injection molding is a contiguous mass of ABS.
However, unless you need many, many parts in a short time, 3D wins for prototyping as the cost of the tool is eliminated.

I certainly wouldn't trust my life to one of my 3D printed parts.

I'm hoping someone out there can shed some light on this whole strength thing.

I have some knowledge but it is limited to what I have worked with; Stan you are correct, the layering type of build process does affect the strength of the part. We have 3 industrial type machines at work that I along with the other 4 people in our shop program and run. We also have an SLA system but that is a completely different animal.

On our systems even when the build style is set to solid the finished parts will have porosity; we use an ultra sonic cleaner to remove support structure and the parts soak up liquid like a sponge.

With that being said parts with substantial cross sectional thickness are quite strong but when the sections get thin they are very week at the bond lines and will snap like a potato chip. Because we build a lot of prototype parts that will eventually be injection molded this can be an issue; especially on things like snap features that need to flex to work. The build orientation can help solve some of this by putting the grain in the strong direction; but do to the part geometry this is most always a compromise. On our machines the down facing surface usually has a better finish so that can also be factored into the parts build orientation.

It is my belief that a printed part using ABS in a FDM (fused deposition modeling) machine will never be as strong as same part that has been machined from solid stock or injection molded.

Understanding the limitations and how to work around them these machines are very capable of making some really cool parts. It’s really pretty amazing after using a 3d printer for a while how your approach to projects changes. You start to think how could I design that bracket so I can just print it and save a bunch of time.

Enjoy your new toy Stan!

Dave

[b.lindsey]

Dave is spot on on what he said. Having used the industrial sized machines at work for some 6-7 years now, the orientation is critical, and wall thickness is your friend re: strength. We had converted our machines to an ABS/Lexan alloy which is still stronger and for anything critical I always printed with full internal fill, unless strength was secondary to material cost in which case I would use more of a honeycomb internal structure. The only thing I would add to Dave's comments is that right angles are inherently weak since there is only one layer supporting the perpendicular joint. Wherever possible, fillets should be used to help this. Most industrial machines also use a support material, either breakaway or soluble, so many times the orientation of the part build was determined to minimize material consumption of the support material in particular. Over the years I have run many parts like air intakes or plenums attached to carbs which were bolted  directly to the engines of the motorsports race cars and used as functional parts. As long as they are not in direct contact with surfaces above their melting point they function quite well. These kids are so good with Solidworks that they can easily design parts they could never machine, and that is where 3D printing really shines.

Bill

[Dave Otto]

All very good points  points Bill

We started out with PC-ABS on our large system but the supports are an absolute bear to remove and seem to be hard as glass and just about as sharp when broken. We usually try to manually remove as many of the supports as possible to keep the solution in the cleaner fresh longer. The engineers didn't mind the difference in strength so we switched over to plain ABS which is much easier to deal with.

The printed ABS threads pretty well but if the thread strength is an issue Helli-Coils work great in the plastic. I just model the part with the hole size for the desired tap.

Also as Bill indicated fillets are always used as practical; and yes with a dual head support type of system orienting the part to reduce the amount of support is always a consideration. Lots of time parts can be built with only a base layer of support and nothing else.

One other little trick is on very small thin structures like snap features; a small bit of solvent (methylene chloride) can be applied to the printed part which will wick into all the pores and void and help strengthen the part after it dries.

Dave

[b.lindsey]

I agree totally as to threaded holes too. The crests of threads tend to be only one or two layers thick and shear off easily. I haven't tried helicoils (though that is a great idea), but rather have the kids specify the tap drill hole size (or slightly smaller) and then tap conventionally. It isn't as strong as in an injection molded part due to internal voids even with 100% fill, but ABS or PC-ABS can be tapped quite successfully, just don't over-torque it.

Bill

Edit: The soluble support material we use is a brown colored material (not sure what exactly). While soluble in a strong soap solution (heated) it is as brittle as glass and I soon learned to use gloves when breaking it away manually. The shards will cut and embed like glass splinters though not to worry...I happen to know Stan has THE best splinter remover known to mankind