Bent leadscrew?

[Joseph Noci 1Participant @josephnoci1]

Does everyone else understand what the problem was and how it was fixed? – Maybe I am a bit daft, but I have no idea what caused this and how bending the leadscrew straight fixed it! Was it to do with what Clive suggested in setting up the halfnuts and leadscrew? If so how did this cause a valley for one leadscrew rotation and a peak for the next – I do not understand…

Joe

[Paul AinsworthParticipant @paulainsworth93685]

The fault was my fitting the apron without lining up with leadscrew. Once lined up correctly the half nuts and leadscrew were not pulling each other sideways.

The bend in the leadscrew made little/no difference, but once I knew it was there I had to address it.

[Joseph Noci 1Participant @josephnoci1]

Still does not explain how one leadscrew 360deg rotation causes a peak and the next 360deg rotation a valley – anyway, I'll leave it at that…

Joe

[HopperParticipant @hopper]

Joseph, If you look at the photo, the peaks are in line with the thread tips, the valley with the thread roots, so 180 degrees variation, in line with slight bend in the lead screw, exacerbated by the apron being fitted considerably out of line so the leadscrew was under tension from being moved sideways when the half nuts were clamped shut. With the leadscrew under tension, the slight bend in it varies the tension, which moves the carriage slightly as it varies, due to clearance in the gibs,, wear in the bed etc creating clearance.

With the halfnuts correctly aligned by having the apron correctly aligned by the method outlined earlier, the leadscrew is in its natural position with no tension on it, so a little bit of bend or runout in it does not move the carriage: the long thin leadscrew flexes enough to remain in line with the supporting halfnuts.

[Joseph Noci 1Participant @josephnoci1]

Hi Hopper,

Thanks, I see it now – it is NOT 360deg rotation of the leadscrew, but a rotation that moves the saddle from a peak to a valley, which is 180deg – Got It…

Should call myself Sill Old Duffer ( no reference the the 'other' one..)

Joe

[Clive HartlandParticipant @clivehartland94829]

My take on it from being an ML10 owner for more than 20 years is that when Paul replaced the stiff bearing at the right hand end of the lead screw he did not align it with the half nuts at that end. It is imperative that the bearing block bolted to the bed does not bias the lead screw as it will lift or pull down on the carriage.

Further to this is the adjustment of the half nuts, they are made of a soft materiel and need to bed in and will need further adjustments later. The adjustment from underneath requires a very small allen key, easy to lose. I tape mine to the top of the belt cover.

Clive

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