Preloaded ballnut vs stock ballnut.

[spaceballs_3000]

Should I go an get preloaded ballnut over the stock? it is really worth $40 per nut? (from cnc fusion)

Also the Heli-Cal zero backlash couplings? (again fusion) has anyone seen how much better these are over the lovejoy connectors.

[RTP_Burnsville]

Depends... If you have limited space a pre-loaded nut may be best. For my application I bought two standard nuts for each screw so I can adjust the amount of pre-load myself. There are many ways to join two single nuts, do a search and you will find examples to get ideas from.

[cadmonkey]

The helical's (if they are the same as what I got from McMaster-Carr) are ok if you have a bit of angular misalignment between the stepper and the screw. Otherwise a solid coupler is the best route. The helical couplers can induce some lash if there is enough resistance in the rotating assembly. I used the helical because I computed the possible misalignment from my finished pieces could (depending on a couple self induced factors) result in up to 0.15° of misalignment. I forget what they are rated for though - for some reason 0.20° sticks in my head. I'm going to turn & tap some rigid couplers out of CRS and see if I lose any steps. That's be nice and cheap and remove any chance of the coupler inducing lash. If it doesn't work it's just time and this is only my hobby (for now...where's that Mister Burns with the 'evil fingers' smiley when you need it...)

Oops - just saw you asked about improvement over lovejoy connectors - hands down I'd go with the helical - I've yet to see a lovejoy spider that would give less than 0.50° of lash AND be rigid enough for a CNC application. If you're doing an X1 or a light duty X2 then maybe - just maybe I'd try the lovejoy, but I'd try and get perfect shaft alignment as the best alternative.

If you use their helical coupler verify that it has 2 setscrews on each end (you only need one flat on each shaft though) - I've found those to be the easiest to use in other applications (power transmission - actual Lovejoy couplers on fan shafts were a lot easier to remove for servicing when they had both the setscrews in them - not sure if the shaft size of 1.25-1.75" diam had anything to do with it though - I know I used the acetylene torch to remove a number of those damned things just to replace a worn out spider).

HTH

[spaceballs_3000]

Depends... If you have limited space a pre-loaded nut may be best. For my application I bought two standard nuts for each screw so I can adjust the amount of pre-load myself. There are many ways to join two single nuts, do a search and you will find examples to get ideas from.

Thanks for the info on the two standard nuts, I'll think sometime in the future I'll have to do this myself, when my pre-loaded wears out.

[spaceballs_3000]

The helical's (if they are the same as what I got from McMaster-Carr) are ok if you have a bit of angular misalignment between the stepper and the screw. Otherwise a solid coupler is the best route. The helical couplers can induce some lash if there is enough resistance in the rotating assembly. I used the helical because I computed the possible misalignment from my finished pieces could (depending on a couple self induced factors) result in up to 0.15° of misalignment. I forget what they are rated for though - for some reason 0.20° sticks in my head. I'm going to turn & tap some rigid couplers out of CRS and see if I lose any steps. That's be nice and cheap and remove any chance of the coupler inducing lash. If it doesn't work it's just time and this is only my hobby (for now...where's that Mister Burns with the 'evil fingers' smiley when you need it...)

Oops - just saw you asked about improvement over lovejoy connectors - hands down I'd go with the helical - I've yet to see a lovejoy spider that would give less than 0.50° of lash AND be rigid enough for a CNC application. If you're doing an X1 or a light duty X2 then maybe - just maybe I'd try the lovejoy, but I'd try and get perfect shaft alignment as the best alternative.

If you use their helical coupler verify that it has 2 setscrews on each end (you only need one flat on each shaft though) - I've found those to be the easiest to use in other applications (power transmission - actual Lovejoy couplers on fan shafts were a lot easier to remove for servicing when they had both the setscrews in them - not sure if the shaft size of 1.25-1.75" diam had anything to do with it though - I know I used the acetylene torch to remove a number of those damned things just to replace a worn out spider).

HTH

CNC Fusion says the their helical couples will not fix their X2 kit without some modification, here is what they said "You will lose a small amount of X travel because the coupling will contact the saddle on the left hand side. We turn the lovejoy couplings down to avoid this, but the heli-cal couplings cannot be turned down. You could grind a small amount of relief in the saddle to allow room for the coupling though."

I'll go ahead an ordered them, since it's not too much work to get them installed.

[LeeWay]

I am using one helical coupling on my mill in the X axis. This is a SS one with an actual spring, rather than the cut aluminum type. I find no lash in it. All my other couplings are solid and steel with two set screws. I made these myself. I tried the lovejoys on my router and they were very spongy. Perhaps I had the wrong spiders, but I won't be using those again.
A shim or two can really help to align a motor to a screw so that a solid coupler would work.

I really like the clamp on type. The helical I am using is this type and they are rock solid. I have had set screws come loose, but now I drill a relief in the shaft and taper my set screws. I use some green locktite and no more coupling woes.

[pzzamakr1980]

I have to second the helical couplings. Even the cheaper aluminum ones are far and away superior to the lovejoys. The lovejoys were fine when i started, but after a few crashes and messups, plus regular usage, they developed a great deal of backlash, so much that I could actually see a gap and feel the movement

[spaceballs_3000]

I have to second the helical couplings. Even the cheaper aluminum ones are far and away superior to the lovejoys. The lovejoys were fine when i started, but after a few crashes and messups, plus regular usage, they developed a great deal of backlash, so much that I could actually see a gap and feel the movement

Wow thanks for the info, I've ordered the metal helical couplings, looks like I'll want them in the long run anyways.

[pzzamakr1980]

Spaceballs I just have to say that I love your avatar. Bill the cat is one of the best comic characters ever, and he never said a word. If you can finish this song you are a true Bloom County Fan

To the tune of Bevery Hill Billies
Wellll, let me tell you the story bout a cat named Bill, poor country pu22y couldnt keep his tummy filled, then one day he was strumming on his tongue, and up came along money by the ton, greenbacks, mula mula.

Apparently, pu22y is a foul word. The cat animal version i mean.

[JustSomeGuy]

Spaceballs I just have to say that I love your avatar. Bill the cat is one of the best comic characters ever, and he never said a word. If you can finish this song you are a true Bloom County Fan

To the tune of Bevery Hill Billies
Wellll, let me tell you the story bout a cat named Bill, poor country pu22y couldnt keep his tummy filled, then one day he was strumming on his tongue, and up came along money by the ton, greenbacks, mula mula.

Apparently, pu22y is a foul word. The cat animal version i mean.

I always loved Rosebud the Bassalope although, Oliver Wendell Jones and his Banana 2000 computer was always a laugh...

[pzzamakr1980]

Lol, oh yeah, the bassalope rabid man eating animal strip was particularly hysterical. And when they (politicians) wanted to start a bassalope hunting season was great as well.

[spaceballs_3000]

Spaceballs I just have to say that I love your avatar. Bill the cat is one of the best comic characters ever, and he never said a word. If you can finish this song you are a true Bloom County Fan

To the tune of Bevery Hill Billies
Wellll, let me tell you the story bout a cat named Bill, poor country pu22y couldnt keep his tummy filled, then one day he was strumming on his tongue, and up came along money by the ton, greenbacks, mula mula.

Apparently, pu22y is a foul word. The cat animal version i mean.

Yeah I always liked Bill the cat
but nope can't finish that song, been too long, though my friend would remember hes the one that got me into it.