Luke11CNC Build Log ,I'm so naïve

[JAZZCNC]

I think the spring method will be better for longer as wear with the double nut will lead to more backlash, whereas wear with the sprung nuts will not have much effect. It will reduce the preload a bit, but you can adjust it so it guarantees that backlash is eliminated. Which is pretty pointless on a router anyway...but I know which method I'll be using when I convert my lathe/mill.
Either way for hobby machines they are used so little (relative to in industry) than wear on the ballscrews/nuts is negligible. If you've used it for long enough to wear out the ballscrews then you've probably made enough money to replace them.

Ok jonathan you seem to know something all the top Ballscrew manufacturers in the world don't so get on with it and good luck.!!

James first I would double check the square is accurate.? Those type of wood working squares are not the best for accurecy.! Ideally you want a good engineers square, longer the better.

The gantry is not neccesorally out of square, check the angle between the cross brace and gantry sides.! . . . Are they 90deg.?
Like as been suggested the cross brace could be short or the rebates in the gantry sides could have been cut fractionly deeper than intended creating the same affect.
If the difference is only small then you could easily place a shim/s in the rebate effectively widening the gantry back to original width and/or use them to bring back into square if rebate is uneven depth or wedged shape.?

Because your using round rail you can accomodate this slight angle difference were the bearing plate meets the gantry side. (Easily fixed with with triangle braces like Jonathan suggests)
Thou it's actually not a big problem if the gantry sides are not exactly 90deg to the cross brace because your using round rail. (If was using profiled rails then yes it would be a big deal.)
Yes ideally you would like absolute square and true but So long as the error is not so great that it affects the screws then you'll be ok

Far far more important is the gantry runs square to the X axis.

I say get your self a good accurate square and some shim steel, It's not un-common to have to use shims to bring things into line or back to square so dont consider it a bodge.!
Far better to hold something square with shims than force it square.!!!

[Jonathan]

Ok jonathan you seem to know something all the top Ballscrew manufacturers in the world don't so get on with it and good luck.!!

All the top manufacturers are aimed at industry where the expectancies (life, accuracy etc) are significantly greater. So if we slightly reduce the life by using double nuts or springs with the same preload it's still going to last a very long time. Most DIY builds don't lubricate the ballnut which clearly is reducing the life expectancy similarly to what we're discussing, however they still run for years... I did consider lubricating mine properly, but when you're rotating the nuts it's easier said than done. Even if you could connect the tube for the oil the oil just flys out.
My comments apply to the C7 screws almost all of us buy where the spring helps compensate for the lead error, not your C1 ballscrew!

James: You can check how accurate the square is by placing 4 equal diameter cylinders in it arranged in a square and measure the diagonals (i.e. placing the caliper across the tangents). If they are equal you know it's good. That's fine in theory... the problem is finding 4 accurate cylinders, bigger the better-I don't advise using your router's rails!

[blackburn mark]

If you've used it for long enough to wear out the ballscrews then you've probably made enough money to replace them.

thats the way iv been looking at it :naughty:

Ok jonathan you seem to know something all the top Ballscrew manufacturers in the world don't so get on with it and good luck.!!

thats a tad aggressive jazz .... in this sport there is an element of "art" and "on the cheep" im struggling to knock jonathans logic till i know better..... out of interest has anyone managed to wear out a ball nut in our DIY circle ?
and did they make enough to replace them lol

[JAZZCNC]

thats a tad aggressive jazz

No "Your talking bo@~#cks Jonathan" is Agreesive but I didn't say that did I.:whistling:

Yes I've worn out a ballscrew, it took 3 yrs and yes it payed for it's self meny times.

[Jonathan]

Yes I've worn out a ballscrew, it took 3 yrs and yes it payed for it's self many times.

You wore out the ballscrew, or the nut and what machine? Did you replace one or both out of interest? Tell me more!

[JAZZCNC]

You wore out the ballscrew, or the nut and what machine? Did you replace one or both out of interest? Tell me more!

One of the X axis screws on my machine, it was the screw mainly but the nut was well tired. In it's defense I've abused them and the hole machine to the point of torcher.
99% of the time it's cut aluminium and with absolutly no protection for the screws from chips and flying debris. . . Some times running constant for upto 36hrs non stop.
It also didn't help that in the very early days I forgot to tighten one of the pulleys and it came off. The other screw kept going and very badly racked the gantry bending the screw.
I had it straightened but it was never the same.

Got some nice quality 25mm Ground C3 doublenut screws for my new soon to be machine. The old machine will be retired to just cutting wood an plastics.

[blackburn mark]

Yes I've worn out a ballscrew, it took 3 yrs and yes it payed for it's self meny times.

splendid .... i can live with that, i give mine an injection of grease now and again and they are pretty clean most of the time :whistling: if i cant make em pay in three years ill go back to wiping backsides for a living :)