The discussion on scraping a bed prompts me to ask about my Super-7 spindle.
Very early in the life of this machine, now over 30 years old, the spindle, um, got slightly damaged - on the conical bearing surface and register shoulder (don't ask). There is now a run-out of the register diameter and the Morse taper of about 1/2 thou. I feel it should be better than that.
How much run-out would you accept?
Not having asked them yet, can I take them just the headstock for new spindle & bearing(s) or would that be a bad idea? Would it cost the earth?
That's very reasonable indeed considering the arm and a leg you have to leave behind when you want an ML7 spindle and bearings. Nothing exotic in it either, just case hardended EN32 and plain old Phosphor Bronze.
-out of curiousity I put a DTI on the spindle register of my 49 year old ex-factory Super 7. TIR was around 2/10 to 3/10 thou, with the variation depending on lateral position. I tried to measure the run-out on the inside of the morse socket, but light scoring made the readings rather erratic. I think the run out is probably about the same as on the register, around 3/10 thou.
True to an extent. The tailstock needs to be dialled in as well as you can first. If the concentricity is a problem you would expect to see the machined work piece tapering towards the headstock because the headstock end is moving eccentrically whereas the tailstock is not.
Knackered bearings will be more apparent when you look at the surface finish of the machined cut. If the surface finish gets worse towards the headstock when turning between centres it obviously means there is play in the headstock.
Mark
Posted Via Usenet.com Premium Usenet Newsgroup Services
Apologies for coming into this at a late date. Insanity, incontinence and too long a shelf life!
I have just aquired a ML7 and had the bed "Blancharded" locally and at minimum cost. Then, someone offered me a Super 7B- a bit rough but OK for its age and price. Whilst doing up the 7, found some wear in the spindle and of course, whitemetal bearings are now unobtainable. Can I change beds? Both beds are the solid old fashioned variety.
Oh, and no cracks about beds as I have already fed the hospital cat.
Just as a point of interest I fitted a new spindle and bearings to my ML7 yesterday. I got new laminated shim packs to go with this, which measured up at between 0.0179" - 0.0185" across the four sets.
After refitting the bearing caps without excessively tightening them down, the spindle was so tight as to be completely immovable. Couldn't turn it even a thou' or so. I blued up the spindle and tightened the caps back on (with shims) to check this.
On the front bearings I got pretty much total contact top and bottom with quite a heavy transfer of blue, and a lighter but again almost total contact on the rear bearing. I ended up peeling a 0.0025" shim off the old pack to put under each side of the front cap and I can now turn the spindle with a reasonably heavi-ish 'damped' degree of resistance.
Levering up on the spindle nose with a bit of 2x4 i can get a total deflection of about half a thou', but can measure bugger all run out with the spindle turning. Running it for half an hour the bearings get warm but nowhere near hot, so I think it must be pretty much spot on now. Still far more accurate then I need at the moment anyway for fitting the end of broom handles.
Thanks, Mark, for the info. The next daft question is the jig to bore the holes for the gearbox. Does anyone have a drawing, please?
I have the manuals for both machines and the box itself. Again, I have quite a lot of ML7 stuff from Martin Cleeve's work. In the spirit of the Forum, I would be delighted to pass on such information as I have. My E-mail is snipped-for-privacy@n-atkinson.wanadoo.co.uk.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.