So you are here, reading this. You like the machine, the demos are persuasive, You aren't afraid of a little DIY electrical but you are unsure of the idea of assembling the machine frame yourself.
This article is for you. We are going to run down just what it takes to assemble a lemontart 33metal machine frame. What's easy, what's hard, and make you comfortable in deciding if "you can do this".
So let's begin with what you need in the way of tools for a "basic" assembly.
- 1st up, a set of metric hex wrenches. 1.5mm through to 8mm.
- Next you need a flat clean working surface that you can also "hang off" the edge of. About 600x500mm is enough space. The more precise a surface the better, but we aren't talking granite surface plate.
- You need 2 spanners for the ball screws - we actually have those in the box of sheet metal parts.
- And we need one other thing in the sheet metal box. the table spacers.
- We need a good dial test indicator. One that reads in 2 microns or 0.0001" increments ideally. You don't need to go spend $180 on a mitutoyo... but you probably should. You will want it for general machining anyway. Do NOT use a dial indicator, this is not what they are meant for.
- A known good square. doesn't need to be granite, but should be as big as you can fine. 250x150 is a usable size, 300x300 is better.
- Some rags and IPA for cleaning.
- And finally, we need grease in a grease gun for zerk fittings..
So now we can begin with assembly. You start with the table, upside down, and begin mounting things to it. The table spacers let you set the correct distance, and then you mount end end frames, and snug it all up. At this point you put in the braces. You should give them a wipe on some sandpaper to make sure there are no burrs, but these are not precise parts. They give to the table and frame beams. Last on the bottom, we put the ball screw in, but aside from tightening the support bearing block onto the screw, we do NOT tighten anything here. We want to loose so we can adjust it. Now stick on the feet and poof, we have a machine base. We will revisit it later for more parts.
Congrats, that was actually the hardest part of the machine to build. No, really.
From there we flip over the base, sit it on it's feet and mount the Y axis rails and then the uprights. And then we put the gantry onto the uprights with their reinforcing beams. Each of these parts have ledges that you are going to butt up against. So you tighten them all up and voila, you have a moving gantry.
At this point, before the machine is too heavy, you are going to tip it up on the back end and now you can install the lower gantry cross, and snug up the ball screw. This part is a little tricky to describe, but it intuitive to do. You are going to set the machine back down on its feet, and move the gantry back and forth as you reach under and tighten things in order. This ensures the ball screw does not end up binding from misalignment. The last thing you wind up tightening is the ball nut to the red mounting block.
Now we can move up, put the X linear guides on, and then build the Z separately, off the machine.
Once the Z is together, with it's stainless steel middle guard in place we can pop it onto the X rails. slide the ball screw in and repeat the aligning like we did on the Y, sliding back and forth. It is a good time to mentioned that ball screws are not fond of being back driven when they have no grease in the yet. You may feel a little slip stick. This is fine, however it may make it hard to "feel" for binding. That's why we set some grease aside with our tools. You should use you grease gun to charge the ball nuts with crease using a provided zerk fitting - then remove that fitting and replace it with the remote push fitting.
Finally you repeat the same alignment procedure with the Z and tighten it all up. You may have noticed we dint bother to measure anything. Nope. That's what we will do now.
We will go through the describe procedure to measure flatness and squareness and straightness of each axis and plane, making small corrections by loosening and tweaking parts. If you follow the instructions well, you should manage better than 50 microns easily over the whole machine travel.
With a more advanced assembly with granite plates and squares, shims and such you can manage better than 20 microns without a large effort. Our prototypes and the production demo lemontart 33metal were tweak with minimal effort to better than 20 microns.
Now, 20 microns frame squareness does not automatically mean 20 microns cutting results - but that is for another article.
- minimonster team