leadscrew flanged bearings

[guido_kp]

So, I've been a lurker for awhile on the site. My first machine is cut out and assembled, it's a JGRO without any deviation from the plans. Figure I need to get it working before i start tweaking anything around on it. So what has me stumped is the leadscrew end bearings. I want to use 1/2 - 8, 2 start for the leadscrews. So what diameter flanged bearings will I need? Will the ends of the leadscrew need to be ground free of threads? If so, then won't I need smaller than 1/2" diam flanged bearings? Some of the flanged bearings I have seen have a set screw to lock the leadscrew down - is this ok or will I need nuts on both sides of the bearing? I havent ordered the leadscrews or the flange bearings, yet, because I only want to do this once. This is definately one of the areas that there isnt much photo documentation about. So if someone has a setup similar to what I am planning, or a better way to do it - lets see some pix!

[ViperTX]

Welcome.....well you can't lock down the leadscrew unless you are driving the nut.....think about it.

Look at the minor diameter of the leadscrew.....the largest journal will be a bit smaller then the minor diameter...

[guido_kp]

thanks for the reply, but that kinda lost me. i think i get at what you're saying, about 'you cant lock down the leadscrew" part...but i've seen guys on here double nut the leadscrew on either side of the flange bearing...i think. i mean, thats what it looked like to me. the nuts spun along with the inner part of the bearing. but then i read how you cant tighten up the nuts on acme rod because it'll just back off...its like there isnt much info on how to support the lead screw and i dont want to order the stuff and then be unable to use it. and i am pretty sure that most of the JGRO guys arent just letting the leadscrew freewheel on the nn-driven side.

forgive my ignorance but i dont understand what this means: "Look at the minor diameter of the leadscrew.....the largest journal will be a bit smaller then the minor diameter."

[randyf1965]

When you turn the end down, it will be smaller than the bottom of the threads

[guido_kp]

ok, i understand now. thanks for the help, guys. i did some more seaching and actually found a couple of helpful pix from spalm and ger21 of how they did theirs. i think i got it whipped, now. gotta order the screws and bearings now!