Head unit design
Head unit design
It took a few more days then we thought in our last update, and for that I apologize, but the head unit design is now fully functionally complete. Is it perfect? No - and we will be inviting several backers who have offered to help with injection molding design (thank you!) to contribute any improvements they have in the next few days, but otherwise it is functional design that ticks all the boxes and is ready for for full prototype testing.
This design had numerous challenges as it is the part that really ties everything together and also the part most effected by numerous other small changes that occurred to the other parts during the design process. The last obstacle to this part's completion was the locations where the belts attach - these have to be in the exact right spot and the last 5 days (and many before that in previous versions) have been spent working and reworking the locations and type of connection points for the belt in order to keep mold costs down, simplicity up, and stick to a minimum number of parts needed to complete the belt attachments. And this all has to be done ensuring the attachment points don't conflict with any other parts of the head unit or the ability to mold it.
What we finally settled on was making the mold slightly more complex by having four holes from the top down into the mold (the mold is a front/back mold) and then having M4 bolts go in those holes and a looped end of the belt attach to those bolts. This allows for easy shortening of the belt for increasing tension (and easy belt changes if ever needed) and the motors also can be slid forward or back in their mounts to increase tension in smaller amounts.
Here is a spinning video of it:
And here is a video showing ~15 of the more interesting saved copies of the model from iterations over the last several days - it might not all look like much as a lot of work was done between the files too - but it shows several different belt attachment systems being tried for conflicts with molding and other mounting points, being abandoned, and finally settling on the bolt setup explained above.
What else is going on with this head unit? The two tunnels through it hold the bearings that it travels on. The two semi circle mounts are for the head unit and the part fan. The part fan funnel has been removed so that you can use any (or just the fan) shape you want for part cooling and the funnel will be a pre-loaded first print if you want to use that.
The flat backside is the mounting for the Z probe for auto leveling and the laser unit for those who got that upgrade. That mounting location is also a great place to mount experimental user created add-ons.
This is a list I've posted before - but with updates - last time we posted it we had a few complaints about "copying and pasting" but I think keeping this list updated is the best way we can show what's next/how much is ahead.
Last tweaks to designs - Over the weekend and early next week we'll do any last minute tweaks to everything (injection and acrylic parts) and take any contributions of tweaks to the head unit.
Test of final injection molded parts and final circuits boards with the final head unit - We have been testing these parts for some time but at this point we need to wrap them all together to get the "ready for production" sample. After that we'll do another set of testing with the first production mold samples. We'll likely start sending both of these types of prototypes to some backers for feedback and testing.
Final package design - the ready for production samples go to the assembly and packaging factory (while molds and such are being made for production) - and they take the box we've picked out, the packing order we've spec-ed, and determine the foam inserts needed to pack it all in with the padding we've spec-ed.
Full scale assembly - at this stage we'll be past the mass production hurdles of injection molding, circuit boards, and sourced parts - this is all about getting the first production runs of the parts and then answering questions about our assembly specs, quality control, and receiving the first many shipments (and random samples on an ongoing basis) ourselves, and checking them. These first shipments will effectively be the first production beta units in that we'll ship them out to backers in return for immediate feedback, this rolls into making any needed changes and continuing production.
Final shipping logistics - concurrent with the Full scale assembly we'll be taking the leads and research we have already and making the final choices of logistics - prices, tariffs, and freight shipment lead times are all over the place right now so there is really no good way to finalize the logistics patterns until we can say "we'll have either several hundred packages or a 20ft container in one week." If it possible to ship to distributors - we're likely to do a short survey for EU backers (Something like: If we ship from within the EU you will have to prepay your customs tax of $X and shipping will take an extra 2 weeks vs shipping it from China and having that tax assessed by your country on arrival with any additional fees customs or couriers may charge in your area - which would you prefer?) Please DO NOT answer that in the comments and DO NOT send us a message - we'll ask it when the time comes. We'll probably have to go by a straight majority as to what we do. US shipments will be shipped from China almost for certain thanks to the 25% tariffs - the rest of the world we're still figuring out the final plan.
The head unit above is printing on a couple of our printers we use for prototype parts right now - we'll also try to get an SLA print of it soon.
With that we'll start to assemble some latest prototypes/nearly completely final prototypes and get some video of where the printing is at now. That will be our next update.
I wanted to take a moment at the end of this update to say thank you - while I've continued to push forward and work hard towards a good ready to ship printer - the most often understandable frustration, but increasingly personal and sometimes completely inappropriately personal attacks reached a chorus the last week or so that even got through the rather thick skin against the personal attacks many years of Kickstarter projects has given me. (I don't need a thick skin for the very understandable and valid criticisms - I take the respectful ones to heart and work hard to make a success out of the project). In my last update I responded to some of these concerns and accusations, because I felt that was the best way to address them. I truly and whole heatedly appreciate the unexpected outpouring of encouragement and support I received after that. Thank you.
Are you totally completely annoyed and frustrated at how long this has taken? I expect most/many are, completely understand that, and apologize for it - and a special thanks to the many who have expressed those things with respect for everyone in this community. I always try to make a point to say - please do feel free to speak your mind, good or bad, about this project here and on our message board - I don't believe in censoring the bad or anything like that - but it is very much appreciated if it is done respectfully.
Thank you all for the support and patience, I look forward to another update soon with some video of the latest prototype.