Category: 3D Printing

Well 3D printing of course

3D print meeting wrap-up, August 22, 2016

Three guests joined us at last night’s meeting: Newcomers Katrina and John and ever-faithful veteran Enric.

Enric spent most of the night tweaking the programming for his cool blinkey roller skates (with 3D printed electronics enclosure).

I walked through a printer demo for Katrina and John, printing a cool statuette of an owl that Katrina found on Thingiverse.

While that was printing we ran through a quick design demo. I keep a few different strengths of dollar-store reading glasses on hand in my shop, and wanted a good way to hang them on my tool-board. So we brainstormed a little hook and modeled it in Fusion 360.

3dp-glasseshook-modelIt’s always satisfying to go from idea to finished thing in one session. This one worked, but everyone had thoughts for improvement as soon as it came off the build plate. The glasses fall off unless they’re very carefully placed on the hook. Maybe a flat section on the bottom and a wider hook portion would make it a bit more reliable. Here’s the Fusion 360 model, in case you’d like to have a closer look, and maybe tackle those improvements!

3dp-glasseshook

All in all, another fun night!

3D print meeting wrap-up, August 8, 2016

Three guests at last night’s meeting: Grant, Charles and our faithful regular, Enric.

Charles has a good deal of experience with Solidworks, and Grant has used 3D printers before, some years ago. We walked through a print job on both printers and talked a great deal about it all.

Grant admired Sean’s Tardis, sitting up on the shelf, but that’s a large and rather involved print,  so we found a smaller Tardis on Thingiverse to use as an example print.

Enric is still making interesting electronic wearables that all need custom cases. Lately he’s been working with electroLuminescent wire!

The big news of the night, if I may say so myself, is that the Type-A Machines printer upgrade is (mostly) complete!

3dp-new-typeaPreviously one had to print tethered to the PC, which can be prone to communication errors, and requires a bit of know-how to do basic things like leveling the build plate. Fortunately the Type-A controller is a standard RAMPS 1.4 board, which is plug-in-compatible with an ubiquitous and cheap LCD/SD card reader module; cost: $8.00. While I was at it, I got a new-style 0.4mm hot-end, reworked the fans, and re-flashed the firmware to match.

3dp-typea-partsI designed the LCD case/bracket and fan shrouds in Fusion360.  Let me know if you’re interested in how that was done.

3dp-typea-panel 3dp-typea-atworkIt all works fine, but I’m chagrined to admit that the quality is still a bit disappointing; layers are a bit misaligned, and extrusion is inconsistent. I think maybe belts need tightening, and maybe the extruder pinch-roller needs a stiffer spring. Still, for less than $20.00 invested, we’re not out much if I can’t manage it.

3dp-typea-resultIt also needs updated documentation, which I’m tackling next. If you’re experienced and anxious to try it out, essentially the workflow is this:

  • Use Cura to slice
  • Export to G-code
  • Save G-code to the SD card (please leave it in the Type A; the SD card fits in the printer upside down;  brass contacts up)
  • Use the LCD menu to select print from SD

Note that the SD cards should not be switched! The Replicator 2 requires an old-style SD card, so let’s please keep them separate.

I also plan to add menu-items to the LCD to assist with changing filament and leveling the bed. And finally, I need to document the firmware tweaks and check it all in to our GitHub account. Watch this space for news!

A replacement part for my winch handle

Last Sunday, Steve and I went sailing aboard the Reboot (my sailboat and home). On about the third tack, I put the winch handle in the winch but didn’t quite get it all the way into its socket. Steve was at the helm, noticed my error and shouted a warning. Alas, it reached my ears a second too late. Under the force of my cranking, the locking lever snapped. Steve immediately remarked “Well, there’s your 3D print project for this week!”

The winch handle is essentially a specialized wrench. The business end is a cylinder machined to an eight-pointed star section. This fits into a mating hole in the top of the winch. At the end of this cylinder lives a small square part which is free to twist slightly (about 22 degrees) and is spring loaded to return to its center ‘misaligned’ position.

When inserting the handle, a slight taper in the hole forces this square to twist into alignment with the star. At the bottom of its travel it reaches a groove in the socket allowing it to spring back to the center-point thus locking the winch in place. To release, you press the lever with your thumb.

3dpwn 01 square locking part

Here you can see the square part, its axle and the thumb lever assembled outside the winch. The spring is a leaf-type located in the lever.

3dpwn 02 lever assembly

With the winch only partially inserted, apparently the full force of my cranking was borne by this square part, transferring the torque to the weakest link of the assembly: the plastic lever on top. I’m lucky it didn’t swing around and bust me in the chops when it let go!

3dpwn 03 broken bits

Anyway, this afternoon I modeled and printed a replacement. On a part that has to fit into an existing assembly, it’s very tough to nail the measurements just right on the first try, so I just plan on printing it at least twice. Fortunately this small part only takes 20 minutes or so to print (leaving plenty of time for this writeup). For my first pass, I simply used the blue filament already installed in the Replicator 2.

3dpwn 05 first try
3dpwn 06 fits on top

It was closer than I expected. The first, obvious problem was that I neglected to use any support material for the screw countersink. I could have tried Makerbot’s support, but from experience I know that a custom support piece works better and is easy to implement.
3dpwn 08 fits on assembly

The next problem was that the part reaching into which the axle fits did not quite project far enough. In this photo you can see that I missed by nearly a millimeter (I didn’t have my calipers when I measured the original… this is as good as I could do with my pocket tape measure).

3dpwn 09 boss is too low

And finally, the little boss that separates the spring snapped off too easily. I made it a bit wider, and shifted it toward the axle by 1mm.

3dpwn 10 spring fits

Confident in my edits, I mounted the black filament and printed version 2.

That worked pretty well, but the spring-return mechanism seemed to be binding. It turned out the spring was impinging on the inner surface of the pocket under the lever, so I hollowed it out a bit more and printed again.

3dpwn 12 compared
3dpwn 13 compared

Success! …except now I found another problem: the boss on the winch handle itself was nearly broken off. This probably happened at the same time. Unfortunately, printing the entire handle is probably not feasible: I suspect there’s a steel part inside, and the plastic seems to be tougher material in general.

3dpwn 14 more trouble

Instead, I drilled a hole and inserted a small screw. Seems to work so far; I hope it lasts!

3dpwn 15 more trouble fixed
3dpwn 16 done

Modeling

Modeling a complex shape like this can be a bit bewildering, since there are so many approaches one might take. Where do we start?

I find it useful to first consider the orientation that the part is printed in. Since there are lots of holes and important protrusions on the bottom, I decided to print it upside-down to minimize the use of support material.

This decision immediately necessitated a slight variation from the original design. This photo doesn’t show it very well, but the original thumb-handle projects upward ever so slightly. On mine it’s flat.

3dpwn 17 done side

Then, what plane to start sketching? I chose the plane at the base of the lever, but above the parts that protrude into the winch handle body. This section is easily measured and clearly defines the basic body of the lever, so it made sense to start there.

That profile is extruded with a slight angle (I picked 4 degrees), which follows the design of the original part. The original was undoubtedly injection-molded, which requires an angle like this to allow the part to be easily extracted from the mold. We don’t have that restriction with 3D printing but I mimicked it anyway (here shown upside-down).

3dpwn 18 body

Then the thumb cutaways. These are made by revolving a profile that was made by eye and a bit of trial and error. Mine does not exactly match the original but looks nice and is functionally equivalent.

3dpwn 19 thumbcut

With a fillet added, it looks even better and is quite comfortable to handle.

3dpwn 20 filletted

A pocket must be defined beneath the lever to accommodate the return spring. This took a few tries to get right. My initial thought was to simply extrude a pocket, straight in from the bottom, but that cut through the thumb cutaways.

Instead I used the ‘shell’ command to uniformly hollow-out the bottom. Then to thicken up the portion around the pivot, I extruded a section. This went through the lever, so I used a sequence of combine operations to eliminate the protrusions, much as I did with the parametric box update.

3dpwn 21 springpocket

The remainder of the model consist of straightforward sketches and push/pull operations. I’ll upload the model for you to explore on your own if you’re interested.

3dpwn 22 complete

It seems to be working so far. Time will tell how long it lasts. PLA degrades in sunshine, so I might have to revise and reprint at some point, perhaps with PET or another more durable material. In any case, I hope this has shed a bit more light on how you can tackle your own 3D print design challenges. If you get stuck, I’m here to help!

3D print meeting wrap-up, July 26, 2016

Wow, just one attendee at tonight’s 3D print meeting. Do I have bad breath? Maybe changing the day loused a few folks up? Or maybe we just can’t compete with the Democratic convention.

Newcomer Bob came by and introduced himself. We had a nice chat. Bob has his own shop, including a few 3D printers. He’s an experienced designer, and was just wondering how he might contribute. So, if you need some design help, maybe he’s your guy! Let me know and I’ll put you in touch.

But, just to have a few pictures to show off, I thought I’d post these.  I’ve been playing around with ideas for a 3D printer design.

After last night’s Fusion 360 class, I decided to try Fusion’s rendering feature. Here’s a screenshot of the normal modeling environment to compare with the rendered image above. I have not experimented with all the available settings, so I’m sure there’s more to be found here, but I’m impressed with how realistic it looks.  That heat sink is supposed to be anodized aluminum; looks spot-on to me!

3dp-extruder-modelspace

3D printing tool board

It’s a simple thing, but one I’ve been meaning to do for a while.  When your tools have a visible home, you can instantly see when one needs to be put away.

These are the tools I routinely use, but this is meant to be a living thing, so if you think an additional tool should go there, add a screw and a label.

3dp-tools-closeup

The Replicator 2 is back on-line

The thermocouple was the only part that actually needed replacing, but while I had everything apart, I also replaced the heater block, nozzle, transfer tube, heating element and thermal insulation. The old one was gunked-up with heaven knows how many years’ worth of melted-on crud.

3dp-rep2-old-and-new-hotends

Another issue was the front fan. The Replicator 2 has two fans; one on the front and one on the side. The side fan blows cooling air onto the workpiece. It’s the one controlled by the setting in the Makerbot slicer. Typically it’s off for the first layer and on for the rest. (Turn it off for the whole job when printing with PET). Please use the slicer setting and do not unplug the fan to disable it!

3dp-rep2-sidefan

The one on the front should be on whenever the heating element is on. This one sucks air through the heat sink, disposing of the excess heat that travels upward from the heating element. It must be in working order or heat will build up and melt the rest of the extruder assembly! Make sure this fan comes on when you start your print job or change filament… anytime the nozzle gets hot. If the fan does not come on, please cancel your job immediately and contact me!

It turned out this fan had a shorted wire. I found a pigtail up in electronics with the right kind of connector and soldered it to the fan. The sharp-eyed will notice that the color coding does not match the wire it plugs into; rest assured it’s correct. There’s a broken blade on the fan, so I have a replacement on the way, but meanwhile we should be OK.

3dp-rep2-frontfan

One more note: A few weeks back, someone mentioned on Slack that one of the ‘home’ switches was not working, causing a grinding sound at the start of the print job. I got the same sound to happen the other day (before the breakdown), when one of the loose wires on the extruder snagged on the left-front corner of the frame, right after the warm-up sequence. It sounds just like a failure of a homing switch. It could be that this is what broke the fan, but I can’t be sure.

Anyway, I’ve added some wire ties to keep the wire bundle under control. You should not have to unhook any of the wires on the extruder under normal use. If you have to disassemble the extruder to clear a jam, snip the wire ties if you must, but please find replacements when you’re done. I’ll get a supply of them for the 3D printing station’s use.

The black velcro thing is used to affix the wire bundle to the filament guide tube. This helps support both during a job, and can easily be removed when changing filament.

3dp-rep2-wireties

In other news…

I just attempted a job on the Type A machines printer, and got repeated communication failures from Pronterface. This has always been an issue with pronterface, but seems to be much worse than before. I’m not sure what’s going on; still needs a bit of investigation.

But at best, the Type A is trickier to use than the Replicator 2, so I’m looking into a newer printer to increase our capacity. Meanwhile I’ve ordered a few parts that should breathe a little new life into the Type A:

  • A new-style hotend with a finer nozzle. This will bring the resolution on par with the Replictor 2, and will handle higher-temperature materials like PET.
  • An LCD panel with SD card reader. This will enable untethered printing and easier job setup.

All this can be had these days for a bit under $20.00, so it seems a worthwhile thing to try. Watch this space for news!

 

3D print meeting wrap-up, July 11, 2016

We had several guests at Monday’s 3D print meet up. Sorry I’m a little late with my wrap-up this week. I also failed catch everyone’s name this time ’round.

We did a some design work in Fusion 360. This has become a semi-regular feature at our 3D print meetings. This week we sketched out a filament spool clip. Filament on a spool sometimes gets tangled like a Demon Slinky from Hell. This can cause a print failure if the filament jams, so it’s more than just a little annoying. I had an idea to make one a bit larger than necessary with provision for a prominent PLA or ABS label.

This, I thought, would also make a good example to demo the printer itself… unfortunately the Replicator 2 broke down. I investigated the next day and found that the thermocouple was damaged, which unfortunately puts the machine out of commission. I’ve ordered replacement parts and will have it going as soon as possible; probably early next week. Meanwhile, the Type-A machines printer remains available.

3dpm-replicator2down

Jaylen and Casper snuck upstairs to do some design work on the CAD workstation. They’re making great headway, and I think we can expect to see some cool results soon!

But the highlight of the night was James’ new Delta printer! James has been working on it for a few months and is starting to get pretty good prints, but still has a little tuning to do. Congratulations James!

3dpm-james-delta-sample

Fixing the Fusion 360 parametric box

Last night’s cool Fusion 360 class inspired me to follow-up on my parametric box article. I found a bug in one of my designs not long after posting it. Fixing the bug illustrates a few interesting Fusion 360 features in its own right, so I thought I’d give a bit more detail than simply uploading a repaired model.

The version for screws is the one that’s broken. Recall that I created a sketch for the screw pillars on the bottom of the box and then extruded it upward to create the pillars and some support structure that attaches them to the sides of the box.

To better illustrate what’s wrong, I’ll create a section analysis. This gives us a cutaway view of the model, without actually cutting it into pieces. I can keep this analysis as part of my design and show or hide it whenever I like.

I start by creating a work plane parallel to the XZ plane, but offset 5mm up.

pbx2-offset-plane

Then, I create a section analysis on that plane. This is found on the Inspect menu.

pbx2-section-analysis-menu

The resulting view clearly shows what’s happened. Note that the support structure does not reach all the way to the sides of the box. The chamfered corners of the box make the reinforcement just a bit too small to reach into the edges.

pbx2-original-section-analysis

If I set the chamferDepth parameter to 3mm the problem is much more pronounced. I can even see it with the section analysis turned off.

pbx2-3mm-shows-problem

So, how to fix this? The problem is that the sketch defining the profile for the pillar support ends at the perimeter of the inside box bottom.

pbx2-original-pillar-sketch

I could simply extend it to the inside or outside wall surface, but then a portion of the extrusion would end up outside the box when defined with a large chamferDepth.

After a bit of experimentation I came up with the following. The reinforcement is designed to deliberately extend outside the outer perimeter of the box by 1mm.

pbx2-new-pillar-sketch

Then, I extrude it to a separate body and cut it, using the box as the tool.  I extended the body by 1mm in the last step to ensure that I always do get two pieces; otherwise the next operation is unreliable.

pbx2-reinforcment-extruded

pbx2-reinforcement-cut

I then remove the outer portion, join the inner portion with the box bottom and duplicate with a circular pattern as before.

pbx2-reinforcement-innerpart

pbx2-new box bottom

Unhiding the analysis now shows that the originally desired structure is in place.

 

pbx2-new-section-analysisThat all may seem a bit convoluted, but it now seems to work with any reasonable set of parameters. A much simpler solution would have been to eliminate the chamfer altogether, or make it a small fixed dimension that would have avoided the problem in the first place.

Download the fixed version here: parametricbox-screws-fixed.f3d

-Matt

 

Taylor Stein of Autodesk showing off Fusion360

A Great Night of Fusion360

Taylor Stein (@taylor_stein) a Fusion360 evangelist from Autodesk came to AMT to discuss Fusion360, how it works and what it can do for hackerspaces.  We had a full house of over 20 people who had questions about Fusion360 and how best to use it for what they are doing.

full house for the Fusion360 class

Fusion360 covers a wide variety of stuff from laser cutting to CNC routing to 3D printing that there was plenty of questions to be had.

Questions from how to export STL files for 3D printing, 2D layout, parametric variable and more where covered.

Taylor showed the way he teaches layout which is to do a quick sketch of the part and don’t worry about lining the parts up.  After the initial layout, go back and use constraints and dimensions to make the shape just the way you want and the relationships between the various parts stay consistent.  This is a different way of layout where the separate primitives like circles, rectangles and lines are defined in relation with each other so as you change one the others move with it.  For 3D modeling it makes things flow far better than having to go back and change everything after one adjustment.

We covered so much material we never really dived into the 3D CNC CAM side of things so another event was scheduled – Monday July 25th Taylor will be back to talk CNC routing and how to do 3D toolpaths and other CNC related questions.

taylor stein of Autodesk showing off the Fusion

3D print meeting wrap-up, June 27, 2016

Five guests made tonight’s 3D print meeting another fun gathering. Newcomers Panos and Phil were here to see what it’s all about, new members Casper and Jaylen came by for more practice with the Replicator 2, and veteran Enric showed up with his cool blinky roller skates again; now controllable by WiFi!

Panos would like us all to know about the company he works for: Fictiv.com. I understand that they facilitate commercial 3D printing and other CAM manufacturing by ensuring that the designs submitted meet reasonable specifications. Then they turn the work over to third party shops that actually own and operate the machines. I won’t post his e-mail address on the web, but let me know if you want to contact him (or maybe try their website).

3dpm-ray

Ray popped down to show us what he’s done with one of the orphan Cupcake CNC printers I put up for grabs. The X/Y motion component was perfect for his new laser engraver! …I’m sure we can expect a full report from Ray once the project is complete so I won’t say more, except that it’s great to see someone breathe new life into old hardware.

3dpm-casper-jaylen

Jaylen found a cool model on Thingiverse. It’s some kind of space-age looking helmet–you’ll have to ask him about the details. We made it exist with the Replicator 2. The author of that model had apparently never printed it before so this might just be the first physical rendition the universe has ever seen.  Unfortunately, the experimental nature also meant there’s lots of nasty support material to remove. Ugh!  Good luck Jaylen!

3dpm-pendant

Then, we adjourned to the next room for another off-the-cuff demo of modeling with Fusion 360. This is much more fun with the cool new projector! Casper was first to respond to my invitation to shout out an idea for a new thing… unfortunately it was the kind of thing I’m not terribly good at: “some kind of pendant,” she said. <sigh>.

But I gave it a shot using Fusion’s loft tool (in retrospect, the sculpt mode might have been a better choice). Nobody has ever accused me of being artsy, but we got something passable thrown together; sliced it in two for easier printing; then printed it on my delta and glued it together.

3dpm-phil-delta

It’s always fun to go from “idea” to “thing” in just a few minutes (even if you don’t identify as artsy).

3dpm-caspers-pendant

Here’s the Fusion360 model in case anyone wants to see how it was done.

The homely pendant

And here’s Enric, just posing like a goofball in case you’d rather see how that’s done.

3dpm-enric

-Matt