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Ah. Thanks for the offer, Tim, but I think I can get by with cobbled together jigs for now.
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Scraping in all bearing surfaces on my Wards/Logan 10"
- Thread starter Rex Walters
- Start date
Ah. Thanks for the offer, Tim, but I think I can get by with cobbled together jigs for now.
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- Apr 21, 2015
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That Richard King is a pretty smart fellow:
I still need to scrape the back in for a nice sliding fit, but I successfully added material to remove the slop. Richard's suggestion worked a treat. You can see that I'll have to remove just a tiny bit of material on the back (left in the photo) edge for the top half to fit.
It's fairly inconspicuous from the side (even more so when I clean and paint the thing). Here's the gory innards, though:
Before doing any work I also followed Rich's suggestion to just lightly kiss the front edge with an end mill after indicating it in as best as I could. I followed that with an extremely light scrape for penultimate alignment with the test bar as before. It literally only took 3 or 4 scrapes for perfect alignment along the length of the test bar.
Next I wanted to ensure that the tailstock mini-way traveled perpendicular to the bed ways (like the cross-slide) albeit just for an inch or so. It's possible that the taper in the quill is aligned parallel to the bed ways, but the front edge of the step or way on the tailstock base might be angled such that the whole top half moves toward or away from the headstock as you adjust the step over. (This is hard to explain in words without diagrams and hand waving).
So I took stuck a mag base and indicator on the tailstock base and swept in a granite square:
First I swept in the short edge of the square by moving the tailstock left and right along the ways, knocking the square (very, very lightly!) with a wooden handled screwdriver until I got zero deviation along that edge. Then I repositioned the indicator as shown to bear on the long edge of the square and moved the tailstock toward and away from the operator. It was a little tricky to because I had to push against the leading edge of the step way on the base by hand, but I'm confident it's well under a single division (certainly good enough for a tailstock).
Finally I got curious to see how the headstock looks before I do any scraping on it. I placed it on the ways for a few quick and dirty initial tests (really tests will come after at least a single scraping pass and clamping the headstock down).
The first thing I did was to indicate the runout on the nose, face, and internal taper of the spindle while rotating the spindle. Far more deviation than I'd hoped. IIRC just slightly less than a half thou TIR.
Then I stuck a test bar like the one I used on the tailstock (but with an MT3 end) and checked the runout at both ends (near the spindle and at the end of the bar). Unsurprisingly it was around a half thou near the headstock (same as when I measured the internal taper directly). It was a good 0.006 or 0.007" TIR at the end, though. Clearly I scraping in the bottom of the headstock will help, but I'm concerned about the runout right at the spindle (I hope it's just a preload issue with the bearings).
Finally, I stuck a dead center into both the headstock and tailstock for a quick visual check of how much lower the tailstock is now:
Scraping in the headstock will lower it somewhat, but clearly I'm going to need that phenolic stock I ordered! Visually, the tailstock is about 1/32" lower almost exactly.
The wonderful folks at McMaster assure me the stuff I ordered should be here before I head up to the class Tuesday night (can't believe they replied to my email on Easter Sunday — love that company). Looking like I should have Rich and the entire class watching over my shoulder as I glue in and scrape the phenolic shim. Perfect timing!
I still need to scrape the back in for a nice sliding fit, but I successfully added material to remove the slop. Richard's suggestion worked a treat. You can see that I'll have to remove just a tiny bit of material on the back (left in the photo) edge for the top half to fit.
It's fairly inconspicuous from the side (even more so when I clean and paint the thing). Here's the gory innards, though:
Before doing any work I also followed Rich's suggestion to just lightly kiss the front edge with an end mill after indicating it in as best as I could. I followed that with an extremely light scrape for penultimate alignment with the test bar as before. It literally only took 3 or 4 scrapes for perfect alignment along the length of the test bar.
Next I wanted to ensure that the tailstock mini-way traveled perpendicular to the bed ways (like the cross-slide) albeit just for an inch or so. It's possible that the taper in the quill is aligned parallel to the bed ways, but the front edge of the step or way on the tailstock base might be angled such that the whole top half moves toward or away from the headstock as you adjust the step over. (This is hard to explain in words without diagrams and hand waving).
So I took stuck a mag base and indicator on the tailstock base and swept in a granite square:
First I swept in the short edge of the square by moving the tailstock left and right along the ways, knocking the square (very, very lightly!) with a wooden handled screwdriver until I got zero deviation along that edge. Then I repositioned the indicator as shown to bear on the long edge of the square and moved the tailstock toward and away from the operator. It was a little tricky to because I had to push against the leading edge of the step way on the base by hand, but I'm confident it's well under a single division (certainly good enough for a tailstock).
Finally I got curious to see how the headstock looks before I do any scraping on it. I placed it on the ways for a few quick and dirty initial tests (really tests will come after at least a single scraping pass and clamping the headstock down).
The first thing I did was to indicate the runout on the nose, face, and internal taper of the spindle while rotating the spindle. Far more deviation than I'd hoped. IIRC just slightly less than a half thou TIR.
Then I stuck a test bar like the one I used on the tailstock (but with an MT3 end) and checked the runout at both ends (near the spindle and at the end of the bar). Unsurprisingly it was around a half thou near the headstock (same as when I measured the internal taper directly). It was a good 0.006 or 0.007" TIR at the end, though. Clearly I scraping in the bottom of the headstock will help, but I'm concerned about the runout right at the spindle (I hope it's just a preload issue with the bearings).
Finally, I stuck a dead center into both the headstock and tailstock for a quick visual check of how much lower the tailstock is now:
Scraping in the headstock will lower it somewhat, but clearly I'm going to need that phenolic stock I ordered! Visually, the tailstock is about 1/32" lower almost exactly.
The wonderful folks at McMaster assure me the stuff I ordered should be here before I head up to the class Tuesday night (can't believe they replied to my email on Easter Sunday — love that company). Looking like I should have Rich and the entire class watching over my shoulder as I glue in and scrape the phenolic shim. Perfect timing!
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Hey, Rich, that's awesome. Thanks! Dunno how I missed this comment. That'll be great. Not sure if there will be a large enough plate at the class to touch it up, but I'll definitely do so on mine after the class if not. Every single aching muscle in my back thanks you profusely! <laugh>
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Oh, this is definitely play, not work. (For me, at least.)
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Heh. The lathe was built in 1947. Would be nice to finish the restoration before it’s 100th birthday.
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Tell Jon that as he said you had a 36" already and figured I was dumping it on you. He also suggested we could cut it in 1/2. I told him, no way and I would ship it home before allowing that. I wrote him and told him about your heavy one was made for doing dovetail ways and not lathe beds. gave Jim a de-mag for him to keep. He didn't know we were writing. I am in Dixon now and will drive down to Jim's place this afternoon to unload my tools. Thanks
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Pretty sure I bought it from Shars (but possibly on ebay). I’ve been very happy with it. It’s as accurate and square as I’m able to measure (within a tenth over the long side).
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