Quote Originally Posted by A_Camera View Post
This is really bad news, I am sorry. I thought you bought 45x90 extrusions, which was discussed elsewhere as far as I can remember. The BF/BK12 fits nicely on those, using 6mm T-nuts, even though the most optimal would be 46mm center distance but the 45mm is fine. Anyway, I missed somewhere in the debate that you did in the end go for something else than 45x90. Hopefully you can use the ones you have now to something else and can buy 45x90 for your project. I normally buy my extrusions from Germany, a company named DOLD Mechatronic. They have good prices and good quality.

Too bad you wasted some money but I guess the lesson learned is to look at technical specs and drawings. While I never spend time on designing a machine in a fancy 3D modelling software, I do spend a lot of time on looking at drawings and specifications before I order something to avoid mistakes like this. Anyway, this is the reality of DIY world. We make mistakes and we learn and hopefully never repeat the same mistakes. Mistakes are made by the professionals also even in the industry, but their DIY is called prototype. The difference is that the prototype never gets sold, so we only see the nice final product, believing that it always looked like that.

Yes, normally the screws are longer than the rails, but with some smart design you can still have the same movement length as the rails allow, assuming the differences in length are not that large.

Regarding the alignment, I assumed you meant parallel alignment between rails and rails, and between rails and screws, plus squaring. As Jazz says, that's what you should spend time on, not aligning the rails with the extrusions. Of course, it helps if the extrusions are also aligned and squared to each other, but the main thing is that all the rails and screws run aligned and are squared to each other.
Thanks A Camera -

Now that i have had chance to get myself orientated this morning - i have checked what everyone else's has used and they are all running 4080!

If I go 45x90, that means all my support extrusions will not fit either!

Most are using much thinner ball screws and also running 12 or 15 rails, where i opted to go 20 to beef it up even more.

I have been looking at the 'carriage' (not sure if that is the correct terminology) that they use on the ball screw to connect to the side plates, this just seems to be a flat plate, nothing like the parts that have come with my ball screws

I need to take some time this evening and re-evaluate the situation.

Thanks

WoodKnot