JGRO Plan Clarifications

[T_Brown]

Now that I have the electronics working and my motors spinning, I am going to begin cutting parts for my JGRO this weekend. I have been studying the plans and putting the entire thing together in my head, but I am confused about two things. The first thing is with the edge holes on dtl16. The middle hole (for the dowel) is located 1.438 from the edge I believe that these holes should meet up with the holes on the Gantry Front piece (dtl20) however the spacing on these are different than the spacing for the uprights. The dowel hole is 1.375 from the bottom. Is the 1.438 just a misprint or am I looking at it incorrectly?
The second question I have is in regards to dtl18 Gantry Bottom. There are four threaded holes that are called out for Jack Screws. What are these used for? I don’t see anything attached to them in any of the assembly pictures. I am planning on incorporating anti-racking cables and these locations would work well for the wheels if they aren’t needed for anything else. Thanks for any clarifications you can give me.

[NB70]

I'm not sure about the first part, perhaps you could wait until you have test fitted the parts before you drill the dowel holes.

The four jacking screws are to support the gantry before you install the long pipes, like four table legs. You have to do this step before you install the bed support structure. You rest the gantry on the base support structure then lower the four screws down (effectively raising the gantry above the base support structure) adjust them until you are happy with the gantry's position - you could check it with a level. Then you install the pipes and raise the screws back up to allow the gantry to move.

These screws aren't essential if you need to use the space for something else - you could raise the gantry using wedges or something

Nathan

[T_Brown]

I was just wondering if anyone had any info on the hole locations. I just don't want to assemble it incorrectly.

Thank you for the tip on aligning the gantry. Since once its mounted i will be removing those bolts, I think i will keep them and just mount the anti racking wheels next to them so that i still have proper clearance. Do you have any other tips for alignment and assembly?

[NB70]

I don't have any particular tips for aligning the JGRO. There was a good website showing how to align a Joes CNC router, but I can't seem to find it now.

You can check that your X and Y axes are orthogonal by doing test cuts of squares circles etc. The adjustment blocks that support the pipes allow for tweaking the axes. I found it was quite tricky to get all the skate bearings in contact with the pipe at the same time.

I rebuilt the gantry using the JGRO to cut the parts out. The second time I didn't tap any holes, instead I used metal threaded inserts which were much easier.