Finally tuned the 3D prints to be almost completely reliable between shield bands in stacks. Made purchases with the Go Fund Me donations. Received the first 60 plastic sheets and dropped them off to be formed. More information on AC unit. We are close to getting out the first batch, and ensuring the next comes soon after.
Go Fund Me Donation Purchases
Thank you everyone for your donations. Between the Go Fund Me donations and outside donations from others, we have raised 1,065$. This is amazing and I cannot thank you enough for your support.
Time is everything. I've done some sourcing for plastic sheets to finish the shields and everything seems to be out of stock from sources with decent pricing. Makes me want to kick myself for waiting a week to hear back from the hospital. I ended up making another purchase from TAPPLastics for an additional 350 plastic sheets. This was somewhat overpriced in my opinion at $850 with shipping, but if they have stock to get the shields done now it will be worth it. I have verified with the vendor that there will not be delays with the 350 sheets at this point.
I have also ordered another $200's worth of filament and elastic button-hole bands. All the supplies ordered will likely cover the ~400 shields we will print and finish this month. If donations continue we will make more next month. If donations dry up I will continue printing bands with the left over filament and sending them to other North-East groups that can finish the shields so that someone can use them. The global effort is on-going and the reason I cant source decently priced sheets at the moment.
Another big thanks to those volunteering their time working with me to get these in the hands of medical workers.
3D Printer Settings
To be honest I have struggled with printing these in stacks due to the interfaces failing between the bands when printing in stacks. Because I am still working while doing this, I don't have the time to swap out single bands every four hours.
The settings for the Prusa shield are tuned to a Mk3s. My three printers are not this printer model, and in fact have issues moving as fast as their profile was set for. I usually print five times slower with PETG than the settings that this profile had. My Mk2.5s is not able to move this fast either without sounding like it was about to to explode.
My first attempts where to use my original PETG profiles to print the band stacks ended up having the interface issues. I tried tuning my best, but I could not resolve this through tuning my profiles for a few days. I ended up resorting to starting with the Prusa profile and working my way backwards.
I think the magic sauce was that Prusa modifies the thickness of the extrusion at specific ratios and slows the print down using modifiers. I slowed down their profile and tuned for the temperatures I usually use for PETG. With some further minor changes, I hit the sweet spot where my speed and quality were acceptable. I kept their layer thickness settings unchanged for both the profile and the modifiers at the interface between the bands.
I can now reliably print 8 bands on each the Ender3 and Prusa Mk2.5s around 20-24 hours per print. I can print 4 bands on the Di3+ every 12 hours. Between spools running out and me not being present to swap rolls, I hope that I can get 20 shield sets made a day.
Plastic Sheet Forming
While the PETG sheets I ordered are pricey, they are also exactly what we need. The thickness is a little more than spec at .75mm (.03inch) instead of .5mm (.02inch). The sheets bend well enough at that thickness.
I received the first 60 yesterday. I dropped these off in Cambridge to get them shaped with volunteer Dave Bates. He is a life saver at the moment because my CNC machine cant be finished. A huge shout-out to him.
The plan a the moment is to do something similar when the next 350 come in. If things go well, I actually wont have my cnc controller replacement before these show up. I will be relying on him at going forward for the next ones too.
Printer Farm AC Unit
I should have mentioned this in my last post, but having the Farm at non-baking temperature is nice with the new AC unit. This is nothing crazy; but the printers will last longer at lower temps, there is less fire hazard, printer consistency will improve, and I wont die servicing the printers. This was paid for using personal funds, as I was eventually going to get one during the hot season anyway.
