Hi all, since years I've been fascinated by Delta printers and their cool looks and mechanics.
I've been reading about them for days on end and eventually decided to buy some crappy 2nd hand butchered Delta that I saw on the web. It cost me €100 inc shipping but I thought it was worth it since there was a frame, motors, linear rails and some other specific parts. In the end it was kind of a cat in a sack (is this an English expression?). There turned out to be everything wrong with it.
This is how it started:
As you can probably see (I missed this):
- the arms are too short
- it's held together by crappy bits
- it's less than basic
- it's put together by someone without attention to detail and lack of knowledge
- it's never really been used
When the printer arrived I saw the shipping label and started to google a bit, I discovered that it used to be a machine that a shop owner tried to build, they own a shop selling 3D-printer parts but apparently don't know how to even build/use a 3D printer!! Amazing. That's why they didn't sell it in their own shop but on an anonymous account of the shop owner to keep the name of the shop out of the listing.
Anyway, I had plans so I ordered magnetic effector parts and designed a new effector and completely rebuilt the machine with new MGN12 carriages and an E3D hotend. Added an SKR 1.3 and TMC2208's. Oh and an inductive proximity sensor to finish it up:
View of the entire machine with the magnetic system:
With this system the dimensional accuracy was spot on in every direction. However I noticed it had some difficulties and I wanted to make it faster and sturdier. The magnets would loosen up from time to time but the max print speed was only 50mm/s. So I went back to ball joints and wanted to use a FSR instead of an inductive proximity sensor so I could measure from the hotend tip.
Now it's been another few weeks and, with great care I have put together this amazing machine that runs really well, but there is only one issue. The X and Y dimensions are not equal. The X-dimensions are too long and the Y-dimensions are too short. It's even noticeable on small parts. A cube that should be 20x20mm is 20.1mm by 19.9mm. Note that I didn't have this issue back when I used the magnetic system. I have printer a couple of nice models that were press-fit and everything snapped together while the parts were randomly oriented on the build platform so all dimensions were spot on.
This is what the machine currently looks like:
Electronics:
Effector:
I have double triple checked everything:
- rod lengths are equal and precisely set in the firmware
- machine is square in every dimension
- endstop height is close to perfect on each column in relation to the heated bed
- after manually configuring UBL the machine prints precisely flat on the entire bed (G29 L1 is in startup gcode)
- distance between rod joints is equal across the board
- belt tension is equal, checked by the sound they make when played like a bass snare and the tension buildup when deflected
- Z-height is spot on
- flow is calibrated perfectly 2 walls of 0.48mm combine into 0.96mm thick walls in each dimension
- effector bolts have no play because I added spacers around the M3 bolts to make a tight fit
- calibrated steps/mm by having the printer move in the Z-height, this works perfectly
Stats (rounded values, not rounded in firmware):
Machine height - 800mm
Print height - 213mm
Diagonal rod length - 267mm
Radius - 109mm
Print radius - 80mm
Bed size - 220mm
I'm really curious if there is anyone that has some advice for me to see what I can try out to get the dimensions correct. I didn't just build the machine to print figurines but also for printing mechanical parts for things I design. As you can see in the effector design I really like to micromanage stuff to make specific one-off parts.
Kind of lost about what I can still try.
Edit;
Just printed a large cicle to test the bed after UBL, and it turns out the measurements are almost spot on when printing a circle that is 155mm in diameter:
Sadly 10 images max in this message, but the Y-dimension turned out to be around 154mm's. So the dimensional error doesn't enlarge towards the edges which 100% confirms the steps/mm are set correctly. Smaller objects actually have more inaccuracy than this huge parts.
Edited 6 time(s). Last edit at 12/25/2019 07:11AM by Ohmarinus.
http://www.marinusdebeer.nl/