Reconditioning a Relmac lathe

[irving2008]

Hi I’ve got a mill and travel from north down to Kent fairly regularly M6, M1, M25, A2M2

Would you be interested in me doing some machining?

Kevin

Kevin, Thanks for the offer. I'm going to look at a short term fix first but will come back to the milling out option if that proves unsatisfactory.

Nice mill btw...

regards,
Irving...

[irving2008]

Well despite my best endeavours nothing got done the last 2 weekends mainly cos of family things but the weekend before last was just too windy.

Anyway, was going to do it this weekend. Got it all set up and then decided to DTI the spindle from the slide and see how parallel to the ways it was. The end result was it was 0.15mm out in 80mm, but I couldnt decide if that was the tailstock being out or something else. As you will recall from a previous post i am holding the chuck end of the spindle in place using an MT3 deadcentre located in the centre hole of a JT6/MT1 arbor held in the tailstock. But the tailstock wouldnt normally be at that end of the bed so i cant tell if the error is due to the tailstock, the centres or something else...

So I decided to order an MT3-MT1 sleeve and an MT1 parallel test bar. The plan is to hold that in the spindle and locate the far end on an MT1 centre in the tailstock. That way the bar will better show the true direction of the spindle over a 300mm length and will allow me to DTI it from the slide more accurately.

The runout on the reground spindle is impressive. It doesnt even move the needle on the DTI so better than 0.0025mm!

Hopefully next weekend!

[irving2008]

Well i ordered the taper sleeve and test bar from RDG on Sunday eve, shipped out to me Monday, arrived this morning. Test bar wasn't as long as I expected, 100mm not 300mm :( Anyway, I fitted it all up for a trial and with relatively little adjustment was able to get 0.02mm across an 80mm traverse with .01mm runout on the taper sleeve. Quite pleased with that (<0.01degrees taper), so no more than 0.1mm out (4thou) over the full bed traverse. So will set it all up tomorrow night (and try to remember to take some pics) to give it time to dry for the weekend...

[irving2008]

well sods law prevailed... I decided before I finally did the pour that it might be a good idea to check the tailstock to spindle relationship when the lathe was actually bolted down and level... well suffice to say the relationship was far from level in the horizontal plane and when the lathe was bolted down and the spindle actually level the good parallel I'd measured went out the window. Eventially after much measuring and cursing I discovered that the lathe bed is twisted and needed packing about 3mm on two opposite corners when I bolted it down. This means I will have to pour the bearing with the lathe bolted in place to the bench. Once bolted down and leveled I then found the saddle would stick badly at a couple of points so I removed all that and cleaned it up, refitted and readjusted the horizontal and vertical gib strips. I also tightened up the leadscrew preload to give 4thou clearance and discovered a hitherto unknown screw that tighens the clasp-nut onto the leadscrew, which allows a modicum of backlash removal. Now it all runs much smoother than before if somewhat slightly stiffer than I would like... taper now measures 0.04mm in 80mm but its more consistent and doesnt vary with saddle travel direction. I also discovered that the tailstock has an adjustment underneath so I'll take the final taper out once the lathe is up and running.

By the time I'd done that on Saturday there wasnt time to do much else and today was a washout (literally and metaphorically) as family things got in the way again...

Hopefully next weekend...