I was talking to a friend who has a Delta printer that he built. He said, “I wish my Delta had a build plate that I could level the old-fashioned way” This got me thinking how hard could that be?
I had a “nothing planned” weekend so I wondered what I could do and then I remembered what he said and decided to give it some more thought. Below is how I made an old style calibration option using some springs, a visit to Tinkercad and a few thumb screws for my Delta 3D printer.
First off, I needed to figure a way of mounting the bed away from the frame. Usually Delta printers have a fixed bed that is fixed to the frame. I can see my friends point. Delta printers can be difficult/time consuming to calibrate. Even when you have it zeroed in there can be times when you want to adjust the first layer to be a bit thicker or change it in some way. And yes, I know you can do that in the settings but it’s just as easy to tighten or loosen some screws sometimes. Anyway, it’s just a test, a proof of concept to see if
- I can do it?
- Does it make calibration easy?
- What are the results like?
First off, I went into Tinkercad and designed me 3 x mounting points. This is quite easy because all Deltas are essentially circles with three towers. But at the end of the day they have to make up 360 degrees. So, each tower is 120 degrees apart (3 x 120 + 360) Looking at the towers you can say that the frame must leave each of the towers at 30 degrees. I made some forms to fit over the frame and measured the distance of the print bed in the following area. I needed to know how long to make the connecting piece. I knew that as long as I had the box section at the right 30 degree angle I could just position the joining brace to bring it all together. I ended up with this brace below to act as a frame to sit the build plate on.
Next, I printed these out and made sure they were a good fit actually they were perfect. Sorry, what did you say? Did I have to tweak them to get them to fit so well? Yeah okay, there were another three iterations of the initial design where I learned by my mistakes and THEN finally they fitted glove like!
I then drilled some holes in the sides to attach then to the bottom frame of the delta.
Then marked out the six holes (two in each brace) that would go to mount the build plate. I thought about only mounting the build plate at the location just in front of the towers using just one bolt, but I thought of some potential issues.
- If I mounted them using two points at each tower that would allow better calibration.
- I needed to factor in a large build and if it got to heavy it might push down on the springs. Two springs are harder to move than one.
- Using six mounting points allows me to use stronger springs thus alleviating the point above.
- Looks more bad arse with six mounting points.
After marking them all out I drilled all six holes. I ran into a small problem because I thought I was going to leave the head of the bolts that hold the springs sticking out the bottom of the brace I’d made. When I tried putting at all together I could not make the part fit because of lack of clearance to get the bolt head in the top gap of the rail and the locating nut holding the brace to the side of the rail.
I got round this by using a slightly bigger drill diameter underneath so the head of the bolt sunk in and was near enough flush at the bottom. That way I had enough room to make everything slot together over the box section rails.
Once I had that little issue sorted out I installed all of the braces at the tower locations. I tightened the nuts and made sure nothing moved and everything was in the right place. So, I have my three braces with the upright bolts set into the brace ready to accept the springs. The braces were never meant to take a lot of force or weight and only ever meant to give the build plate some form of extra calibration movement. Like so.
Next job is to place the springs over the bolts ready to accept the build plate. I used quite strong springs because of a couple of reasons.
- Weight of the build plate
- Potential weight of the object + the above
What I didn’t want was the over all weight starting to exert a pressure on the springs and make them compress. This is why I decided to go with six calibration points. I was spreading the weight to give the whole set up more rigidity. If you want to do this yourself, here are the parts I used http://amzn.eu/6r39vFD
I will also include a download to the parts I 3D printed so if you want to drag them into Tinkercad and change them to fit your own Delta, please feel free.
Now it’s time to fit the build plate over the bolts and springs.
Now lets cap them off with some nice gnarly thumb screws and we have the build part done.
After the build I tested it with some calibration prints and I did some large 0.02mm prints trying to get further and further towards the edge of the build plate with perfect coverage. I have to be honest it was really good and my build plate is at the moment perfect from the middle out to each tower.
This is my first proper print and it turned out really well. The underside (important in this print) was flawless and the face was as smooth as a baby’s skin. All in all I was very happy.
So, was it worth doing? Yes I think it was, and having seen it in action I can see one major improvement I could make. At each of the towers I could add another bolt but instead of using it to pull the build plate down. I could use it to push that part of the build plate up. Think “car jack” that way I would have both directions of movement.
How has it helped me 3D printing though? Well I was able to get just the right gap in height to print PETG without using a heated bed and without having to play around in the firmware. Okay so that reason was a little tenuous but it was fun so that’s all that counts at the end of the day ;O)
If you want to download the 3D printed parts and use yourself you can get them here, below. Feel free to change them as you see fit. Let me know how you get on.