Advice regarding my worn nuts

[RobCox]

I am tempted to use that the only reason why im tempted to solder is the narrow split part that is used to adjust backlash do you think it would still hold on that

Well, if it lets go it would be easy enough to get apart, clean and go down the soldering route. Dont see why it shouldnt hold though if the surfaces are properly cleaned.

 

[DAPPH]

I used green loctite on the y axis feed nut on my mill. No sign of problems after 7+ years so I guess it's ok. A lot easier than soldering or brazing!

We used green Loctite to take 21 thou up in a bearing mounting hole on a Thorneycroft Mighty Antar tank transporters gear box rear out put bearing without problems , but everything must be super clean when doing it . IIRC we used Ether & lint free gauze pads from the medical centre .

 

[dieselsamurai]

Citrix acid cleans brass up like new i'll try that first

 

[dieselsamurai]

So the nuts are now bonded in the holder with high strength locktight i found for what i will be doing it will be fine



But test fitting threw a curve ball and may explain why it was loosely fitted in the first place

the mounting for the leadscrew on the right side is not inline with the one on the left pictures below clearly show drilled offset



measuring it its not terrible on the leadscrew about 2.4mm but a massive pain when i was about to re-assemble

even the left hand mount the bolt holes are not inline one is lower than the other



At least the lead screw hieght is ok i dont need to mess with that , this is why you need 2 mills to fix the other one when it goes wrong now i deffinately need another lathe just in case

Need to work out a way to fix it now

 

[Agroshield]

the mounting for the leadscrew on the right side is not inline with the one on the left

What are you using as your reference line?

I think (please think this through for yourself and see if you come to the same conclusion) the leadscrew needs to be parallel to the dovetails. In addition, its centreline needs to be in line with the centre of the nut when the nut is screwed to the saddle. And the nut needs to be parallel to the dovetails.

Any symmetry in the fixing of the endplates only points to a symmetrical casting. It is not in and of itself a necessity.

In a way, you need to put the nut in place, put the leadscrew half-and-half through the nut, make sure it is parallel to the fixed dovetails, slide on the table and fix the endplates to the table where they touch, ignoring the surrounding casting.

Slot the holes or counterbore for mahoosive washers (eccentric if necessary), line everything up and tighten. Then drill and ream the two parts for spring or dowel pins.

 

[dieselsamurai]

What are you using as your reference line?

I think (please think this through for yourself and see if you come to the same conclusion) the leadscrew needs to be parallel to the dovetails. In addition, its centreline needs to be in line with the centre of the nut when the nut is screwed to the saddle. And the nut needs to be parallel to the dovetails.

Any symmetry in the fixing of the endplates only points to a symmetrical casting. It is not in and of itself a necessity.

In a way, you need to put the nut in place, put the leadscrew half-and-half through the nut, make sure it is parallel to the fixed dovetails, slide on the table and fix the endplates to the table where they touch, ignoring the surrounding casting.

Slot the holes or counterbore for mahoosive washers (eccentric if necessary), line everything up and tighten. Then drill and ream the two parts for spring or dowel pins.

This is exactly how I worked it out i wouldn't use castings for reference , I had the nut mounted to the saddle with the it fitted to the table upside-down as shown above . I noticed it was getting tight as soon ran it closer to the righthand endplate thats when i found out by loosening the bolts holding the nut that it was trying to move to the front of the table thats when i measured OFF THE DOVETAILS that the leadscrew was off the center axis by 2.39mm , I also measured the hieght from the dovetails using parallel's and a bar across and the deviation from right to left was only 0.08mm.

I see now why the bolts holding the nut were loose when i stripped it down but this caused the nut to wear way more than acceptable

I slotted the endplate as below and now it runs freely from end to end with no binding , i had to shim it by 0.7mm but thats not far off the 0.75mm i dropped it when i bored it out so pleased with my calculations



I just need to do a final fit up and drill ream and pin it like you mention and I can start reassembly

I tried the X axis nut and that runs up and down smoothly too with no binding

 

[dieselsamurai]

Slowly going back together not a full resto but should be easier to drill or mill with now as there was 3mm of play in the X axis at least



Took the opportunity to add a remote Y axis dro



Table on and everything is so much smoother just got to add the X axis Dro and leadscrew and i can check the play

 

[dieselsamurai]

Finally finished , now got X,Y and Z readouts and only about 0.05mm of play in the feed nuts and that good enough for me ! thanks for all the input and advice



just got to cut a bit of perspex to go over the X axis Dro but 3d printed brackets worked out great