New JGRO build for Matt888 started with Q's inside...

[matt888]

Pics to come soon. I decided to build the JGRO machine to get my feet wet and then possibly build a larger one later. I've got about 40% of the stock cut and already have a question...

Throughout the plans, there are several locations where one must drill a .69" hole. I'm having difficulty finding the .69" hole saw or spade bit to meet the criteria. This hole size appears to be everywhere the 1/2" rod terminates (opposite side of motor driven end on each axis). Does a bearing fit in there perfectly or something?


Thanks, Matt

[silentreaper]

I used an 11/16 drill, 11/16=.6875 so as far as my build was concerned, close enuff.

EDIT: forgot to mention that mine was a spade drill, and my bit and drill press must have been plotting against me cause my holes ended up a bit on the big side.

[matt888]

Originally Posted by silentreaper I used an 11/16 drill, 11/16=.6875 so as far as my build was concerned, close enuff. EDIT: forgot to mention that mine was a spade drill, and my bit and drill press must have been plotting against me cause my holes ended up a bit on the big side.

Thanks. I'll look for one next time I hit HD.

[matt888]

The last few weeks have been fairly slow moving, but I did get a few things accomplished:

Finished up the CNC package and threw it in a quick wooden enclosure. Nothing fancy here at all. I figure a nice enclosure will be made once the machine is operational down the road. I haven't tested the control package yet and I still need to go back and adjust my driver current levels down to 70% of max. I wish the instructions stated this when you are actually building the ic board. It doesn't tell you to set the level at 70% until you get into the actual enclosure build instructions. By then, you've already set your current at 3A per motor (I have the larger 305 oz motors) with the axis potentiometer adjustments and moved on. No big deal, but now I have to move the jumpers and find my 12V power supply again.

Other pic is just the mess of MDF parts laying around and waiting to be assembled. I don't have anything cut out for the base yet. I think I'm going to wait until I get my double-sided shielded bearings in-hand before I drill the MDF holes for those bearings to make sure they fit snug. I went with the 1/2-10 acme rods and 1/4" to 1/2" lovejoy couplers. Ordered those parts today. I'm not sure if I'm going to go with the dumpster CNC anti-backlash nuts or rig something up myself as of yet.

2 quick pics below. I'm off to cut more MDF...

[matt888]

What tap can I use for the Acme 1/2-10 rods I have coming? Is there another option other than the $50 tap Enco sells?

I guess some people have made a tap from the threaded rod itself, but I don't have the equipment to do that.

Kind of an expensive tool to only use a few times making the machine.

Thanks!

[matt888]

I didn't want to start a new thread so I hope someone reads this new question...

Why does the z-axis use only one bearing and a spacer instead of the 2 bearings used on each of the x and y axis on th JGRO design? I'm not grasping the reason for the difference?

EDIT!!!

I found a few threads that show people using homemade plastic nuts on this axis instead of backlash or bearing setups. I'm going that route...