This is where the all fun begins but also one of the most important part. I will not stress this enough but the printer is a really accurate piece of kit so build it in the same way ! Take your time, measure, measure and measure again to make sure that everything is square and nice.
Before you start, you need a few things. First some tools to be able to ty up the screws ( of course ), some nice square to fix the rails a perfect 90° and a flat surface. A caliper digital is also a great aid. I personally did not use the printed jig as I did not trust my old printer.
For the squares, I tried a few that I had home, you know the one you can get in the cheap home improvement shops. And it did not great. After looking a bit on the internet and trying a few different one, I really like and got great results using this one. It is simple, easy to use, you can setup the rails nicely and perfectly to each other’s and it will scratch the surface. I got myself a 140 mm which was perfect for building the frame as it got almost in every corners.
Another word of caution, the drawings made by Ben ( thanks again for that ) is mentioning a 36.75mm distance from the top frame. At the bottom, the rail should be 20 mm from the bottom but there is no part or distance anywhere else on the drawing showing a distance ending with .25 mm. If you build the frame like this, you end up with a 1.25 mm gap in the middle !
First of all, we have to build the sides. Here again be accurate when putting everything together otherwise your Y and Z axis will be not be square and you will have some trouble later on.
Attach on the top rail the two vertical rails. Use the square to make sure everything is square.At best, put the rails you want to attach on a flat surface. I personally used a large tile left over from building my bathroom, they are perfectly flat. You can use any other flat surfaces. When you put the frame together, only attached the flat corner parts. The 90° corners you put inside the rails can be mounted later on.
At that point it is a good idea to mount the HIWIN rails. Mount the Y carrier Lower part you printed on the Rail carrier and mount the rail on the profile. Make sure you put it in the right slot ! :-). Do not ty all the screws from the rails, just ty up the one at the ends of the rails, you will need to adjust them later on. However, you will have to have a small hexagonal key as the second rails is going to be in the way.
Mount the second horizontal rail from the top at the 36.75 mm distance. It is a kind of a funny distance but an important on because it is the distance from the bed. You can start to use the square for that but it is difficult to get the distance perfectly. Use a caliber to make sure you get the distance as best as you can. It will never be perfect but do your best to be within a few 0.01 mm of the target distance. Tied up slowly the screw and a little bit at the time in alternance to each other and it should be fine. If necessary repeat the process a few time to get it right.
After that you can put the vertical profile that will support the Z Axis and the bottom horizontal profile . Make sure you have the right distance for the vertical Z Axis support. I personally did not fit this element in full at the beginning to make sure I can adjust it later on when the heat bead is mount to have a perfectly square Z axis to the XY axis. I only fixed it with 2 mounting. The bottom part is easy.
Make sure here again that everything is square using your square and by measuring the diagonals distance of every “frame” you have. If you seen that something is not identical by measuring the 2 diagonals, you frame make be skewed and will ne too be adjusted. Make also sure it is lying perfectly flat on your reference flat surface with any movement. If you have managed that, you are all good and can do the second side.
Now you have two lovely and perfectly build sides, it is time to put them together. It is fairly easy, only three profiles to mount right ? Nope ! Here again make sure tha everything is square and measure again the diagonals. When the two sides are attached to each other, make sure to measure the distance at the top at the front and at the back. Because there is no profile going across the front, it is possible that the two sides are going away from each other. Measure, measure and measure again. If it is the case, lose the screws at the front corner and straight the sides. To help you, you can mount one of the 20×20 profile at the front top of the frame. Make sure that both side are perfectly aligned with the end of the profile and it should be perfect. Here again measure again ! When everything is aligned, ty the front screw at the bottom profile slowly and one after each other. Do not ty each screw super hard but first lightly, go through all the screws and a bit more again on all and finally ty all of them. This will prevent by tightening a screws, it will bend or move the frame !
When you have done this, you should have a perfectly build frame. If you see that something is not quite the way it should, just unty slightly the screws on the corner parts, aligned and ty up evenly. You can finish the frame by putting the 3 20×20 profile across and you should be done.
I hope it will help you getting the frame together better that I did. To be honest, I build this frame 3 times before getting it right. Leave a comment to tell me how you were doing !