Glassblowing update for Nov

With the furnace cold, I removed the broken lid and had a look.

The metal is actually thick sheet metal, and in good shape, so no change needed. The brick lid was broken into four pieces, so was discarded.

The new lid was about 1/2 in too long as was the last lid, so I cut the new lid down to size, and now it fits perfectly without distorting the sheet metal. I cemented the cut face with two coats and cured it in the annealer at 100F. I then installed it in the metal frame. As it turns out, painting the fame clogged the fastening clamps, making it very difficult to properly secure the brick in the frame. In the end a set of pliers and a ratchet got the job done.

The furnace is clean, crucible vacuumed out and all is ready to go hot.

More 3D Printed goodies

A week ago the ancient electric pencil sharpener died. The motor could be heard spinning when  a pencil was inserted, but no sharpening action. I took it apart to find the large gear that drives the sharpening mechanism was broken in two pieces. As I shook it out, it broke again. Time for a new unit? Not with a 3D Printer! Before I gave up on this item, I would try and print a replacement gear.

Designing gears is not fun, but the on-line CAD program Tinkercad had a community supplied gear builder. I took measurements from the broken gear, counted the teeth (70) and designed a new one. My first print wasn’t correct. The broken gear did not reveal the drive slot was only partially into the gear, with a round shaft for the rest. Once I had one new gear with the slot all through it was easy to see what needed to be done. The next gear fit well and worked. It’s noisy, but it works.

 

The next challenge was designing an optical connector for my underwater camera housing. The very expensive part from the manufacturer (double any equivalent price) screws onto an optical fitting on the housing. The bare cable has an optical end, but must be mechanically connected to the strobe and housing. On the strobe it’s a simple hole, but I needed something similar on the housing. Again using Tinkercad, I was able to design a simple connector. It took a few tries to get the sizes correct as things must be tight but still fit. After 5 tries I had a good fit. Now to take it to the water for a test dive.  The optical port is shown mounted on the housing on the upper center left.

FLSUN delta printer update for 2017-10-24

Yesterday the new aluminum extruder came from amazon.ca for my delta printer. It was nicely packaged and although the instructions could have been better (b&w photos aren’t great for assembly), they were adequate.

I removed the original plastic-parts extruder and installed the new extruder. It was immediately obvious the mechanism is much better than the original. The toothed wheel is a much finer tooth count, and the idler wheel with notch is much smoother. The spring tension is not adjustable either from close examination nor from the assembly photos, but seems to work in an excellent fashion.

The only hiccup was when I tried to test the calibration. No matter what, I could not get it to extrude. Finally, after much frustration, I realized the two settings in pronterface are not extrude lenght / reverse length, but rather settings for 1.extrude/reverse length and 2. extrude/reverse SPEED. Setting it from the default of 10mm/min to 120mm/min (2mm/sec) was all it took to see some action. Unfortunately the operation was now reversed due to placement of the idler compared to the original extruder.

Fortunately there’s a setting in the configuration.h file for stepper direction which includes the extruder stepper. Flipping the binary option caused the extruder to properly extrude/reverse. Due to the finer gear spacing, asking for 1cm gave 1.4cm. It’s a quick parameter change to fix that and confirm requesting 1cm now gives 1cm extrusion (and retraction).

Finally, I reconnected the filament and tube to the hot end, burning myself severely in the process (2nd degree on a finger which slipped). Once connected I made a test print of the benchy (boat). The first layer is still off, but now at least I can make adjustments knowing the extruder is functioning properly.

Final lesson learned: 185C is VERY, VERY hot. It will cause an instant 2nd degree burn as I found out to my distress. Fortunately immediate cold water followed by ice for 2 hours has reduced the damage significantly.

So… I guess I’m NOT done with Apple

My iPhone 4 is so old now that it’s really getting flakey – freezing up at the most inconvenient times requiring a hard reboot and all that.

So I checked my Virgin mobile plan, and I have some money in the (discontinued) supertab plan. In fact, enough to get a new phone. Now I know there are new phones for $0 on a two-year plan, but I was looking at what I could get for the supertab balance I had.

This is nice as there’s no other way to use up the supertab, so why not spend it on a new phone?

Anyway, it quickly became apparent that Android was out. The phones were either way too cheap, or way too expensive. Besides, I’m not all that thrilled with Samsung phones either as they give you a Samsung mangled Android, not the pure deal.

So what did come up in my search within my (no cost) budget? An iPhone 7. Yep. Apple stuff.

So I went out last week and got it, and it’s actually a very nice phone. More cool, I was able to move all my stuff off the old phone to the new phone in two painless steps as I still have the Macbook available. All I had to do was turn it on, update whatever was out-of-date (including iTunes) and then backup the old phone and restore the new one (data and apps only).

The new phone is, as I said, pretty cool. It’s nice to have something that will last for a few years before getting orphaned again. If the iphone 4 is any indication, that was not really a bad deal for me.

The only thing I had to do was sign up for my same plan for 2 years, which I was using anyway.

So I’m an apple dude again. Kind of. 😉

3D Delta Printer Update

I was not happy with the first prints out of the delta printer. In spite of upgrading the firmware from Marlin 1.0 to Marlin 1.1.3 and running the auto-calibrate several times, things were not as good as I wanted.

One problem was with one axis end stop, which turned out to be loose on the rail. The square nuts (instead of true “T” nuts) was the problem. After much fussing I was able to tighten it, but I think I’ll be buying some proper “T” nuts soon. With that fixed, things were better, but still not great.

I realized another problem was the “probe offset” might not be correct. The Marlin 1.0 default was 0.2mm, but the Marlin 1.1.3 default was 0.7mm. I was using 0.7 and the first layer height seemed high (it wasn’t printing the first layer at all).

Yesterday (Oct 12) I manually calibrated the printer using the paper strip method, then checked the additional distance from “0” to where the probe end stop triggered. It turns out to have a bit of a dead zone. Using the default test height of 315mm, zero was found at 1.13mm. The probe end stop triggers ON at 0.83 but OFF at 0.93. In the middle is a dead zone (0.83) that is either ON once triggered, or OFF before triggering.

As the auto-calibrate uses the probe trigger point, the distance between zero and trigger on was 1.13 – 0.73 = 0.4mm. This was more than 0.2 and less than 0.7 explaining why the auto-calibrate height number was off.

Using the new depth (315 – 1.13 = 313.87) and probe offset (0.4), The prints should be good.

Except they are not.

Watching closely while it started printing, I saw the problem immediately. The bowden extruder mechanism which decouples the extruder from the hot end was not feeding filament properly. Frequently the extruder gear was turning, but no filament was moving. There’s an adjustment wingnut to set the tension, but I found with experimentation that it is just too finicky to work reliably. It seems there is not setting of the tension that will always work first time, and you can’t be fiddling with tension all the time during a long print.

Examining the bowden extruder mechanism, I think I see the problem and the solution. The mechanism is plastic. The idler is a bearing and washers, but the tensioner is just a bolt and wingnut. What is required is a good quality aluminum housing with spring tension similar to that on my cartesian 3d printer that I built.

A quick search on amazon.ca found several excellent choices in the $13 range, so I ordered an appropriate one. It should arrive next week and I’ll resume the testing. I’m quite certain a good extruder will solve the final problems, and perhaps with a final auto-calibrate I’ll be up and running.

Of course, Marlin is now at version 1.1.6, but I’ll hold off trying that until after I get the current version working.

Glassblowing update

Now that the furnace is cold, I’ve had a good look at the lid. In addition to trimming the bricks back to 13.5 x 13.5 inches, I need to replace the metal strip holding the bricks in place.

The original plans from Mark required 4in galvanized sheet metal flashing, which I could not find. I took aluminum flashing and cut it into 4in strips, and that has worked fairly well for years. I’ve replaced parts of it at least once when the tightening mechanism tore the thin aluminum, but it seems to need replacement again as it’s been deformed by the too-large lid.

This time I plan to obtain some 4in sheet metal, somewhere between 24ga and 30ga, with me leaning towards 24-26 ga at the moment. As I cannot source a roll of 4in sheet metal flashing anywhere, I will try Metal Supermarket and see if they will cut me a few 4in slices off some sheet metal.

Stay tuned…

Glassblowing – last day (for now)

Today I made four larger pumpkins, which filled the annealer and pretty much emptied the pot. Afterward, I turned off the furnace, which will now cool from 2100F to around 50F over the next week or so. The furnace is very well insulated, so it takes a long time to cool.

Once shut off, I need to attend the lid that cracked and trim it to fit the steel frame more securely. I plan to modify the current lid (assuming the crack is not too bad) as well as the spare lid I made last year as both were made to the same size, which is definitily too long. Afterward, I plan to restart the furnace in the last half of November, unless the weather is really horrid.

Glassblowing update

Yesterday I blew glass again, making some larger pumpkins as well as some new color Christmas balls. I recently received my glass order from Sylvie at Colourfusion (in Ontario), and it included cobalt blue (opaque) and a light blue (opaque). The light blue with a cobalt stripe is really nice, as is the straight cobalt c-ball.

I also ordered and received a new 4in optic mold from Steinert Industries. This one is a beautiful ribbed mold that is closed on the bottom. My other molds are open bottom. The nice thing about a closed bottom is that it can be used for small or medium gathers equally well. This enabled me to make both small and medium pumpkins.

On Saturday’s session, the gathering port lid fell out of the steel frame as I was starting my second c-ball. It landed with a thump on the furnace. Although it cracked in half, it still covered the crucible. Thinking quickly (things are at 2000F) I was able to push the pieces together with my large tweezers and move the lid to where the steel support would fit and close. I was then able to adjust the attachment clamps to firmly hold the lid so I could finish the session. There was a bit of brick dust on the top of the molten glass, but I gathered it out easily on the next piece.

When I shut off the furnace later this week for maintenance, I will have to modify the lit to better fit the support.

As to the glass, the new bags of Spruce Pine are melting well. When I first received the order over a year ago August, the bags were rock hard and the batch had many hard lumps that would not break. For some reason, just sitting around in my shed for a year has resulted in batch that is still hard, but breaks up into nice batch with a single bag-drop onto concrete as is considered normal. The glass is also really for the entire pot. I do love melting Spruce Pine.

I’ll take some photos of the pumpkins and c-balls  later in the week and post them here.

Printer update

I’ve been busy blowing glass the past week or so, so haven’t spent much time with the 3d printers. I did print 8 more weight collars for the weight bench, installing 4 of them last week. They work really well and are easy to print. Printing 4 at a time is easy and takes about 2 hours. What  is even nicer is the new brand of filament is not jamming at all feeding the original cartesian printer, so I don’t have to monitor the print all the time.

The delta almost printed a nice cube. Only the base was off, and on reflection I think it’s because the setting for ‘probe offset’ is too large. The probe offset is basically the distance between the extruder tip touching the printer base and moving enough (into the base) to trigger the probe microswitch. There were two values in the Marlin firmware – 0.2 and 0.7. I’m using 0.7 right now and I think it’s too much, so when you calibrate the printer the final distances are out by a small amount. Not much, but just enough that the extruder is farther away from the bed on layer one than necessary for a proper first layer.

I need to spend some time with raw gcode to find the actual probe distance for my printer and then use that to recalibrate. Perhaps later this week or sometime next week.

 

FLSUN Delta not quite there yet…

I’ve been working with the FLSUN delta printer I built from a kit this week, and although it has printed a few of the test cubes, it’s still not quite fully functional yet.

It turns out delta printers are a lot faster than cartesian (x,y,z) printers, but with that speed comes some rather unique challenges. The first is that the printer, being tripod and pendulum based, really wants to print in an arc. To counter this, the software needs to know a lot of details about the printer, such as segment lengths and arcs in order to calculate various angles and offsets to use when printing.

Fortunately the delta code firmware I’m using (Marlin 1.1) now has an auto calibrate feature that works with the built-in z-probe on the FLSUN delta. Not all deltas have the z-probe, but it’s easy enough to add to any printer. Basically it’s a microswitch down near the extruder that detects when the extruder is near the print bed. On the FLSUN, the switch is triggered by a rather ingenious lever mechanism built into the extruder mount. When the tip touches the bed, it rocks slightly and trips the microswitch. You can fine tune the triggering pressure so that it’s very accurate. There is one compensating measurement you must take, and that’s how much deflection occurs when triggering. That is, the extruder doesn’t just touch the bed, it touches it a bit MORE than when printing to tip and trigger the switch. You need to know (in mm) how much this extra movement is so the software can compensate when calculating actual bed height.

The auto calibrate touches the bed in a set number of places that can be programmed (n*n, with n=4 as default). It can then calculate various angles and offsets that you then either save in the printer firmware eeprom or hand code into the software. I chose to hand code. The default calibration runs until a set standard deviation is achieved, so it’s quite accurate.

Once the auto calibrate is done and the information encoded in the firmware and uploaded to the printer, you can print.

My first prints were terrible. I quickly realized the extruder calibration was off. Extruder calibration is done with auto calibrate but must be done separately. Mine was barely moving, so after some experiments and adjustments, I got the correct parameter (stepper steps per mm of filament) and that was OK.

However, the next several prints were all still bad. I quickly found one of the three end stops that controls the position of the extruder was loose. After adjusting and tightening, things were much better, but there’s still a problem with the print.

The first few layers (about 1mm or so) are offset from the rest of the print in one direction. It’s consistent and repeatable at this time. The rest of the cube is perfectly straight, so it’s a “first layer” problem. So far I have not found any solution on the internet.

One hint that I’ll be pursuing is that the height measurement of the cube is only 19mm, while the sides are both 20mm perfectly. That implies again a “first layer” problem, possibly too hot. I am also considering the fact that this printer is incredibly fast. It’s almost twice the print speed of my first (cartesian) printer. It’s possible that it is simply printing the first few layers too fast, which may also affect the temperature of those first layers.

My next steps are to compare speed parameters between Marlin 1.1 (my current firmware version) and Marlin 1.0 (supplied with the printer) and my cartesian printer (also Marlin 1.1, but much slower settings). I will also try slowing the first layer in slic3r as a quick test. If slowing the initial print speed works, then that will be great. For now it’s a wonderful printer that has yet to realize all it’s benefits (and yet to make it’s first perfect print).