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- Sep 1, 2023
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EDIT: Oh, that's for the cross slide, thought it was for the lead screw. Eh, I'll leave the below as is anyway.Ok, well, I posted up about part of this previously and mentioned I needed to make a bushing spacer. Check POST #7,563 (<<< LINK)
Finally found time to do that today, so other than trimming the end of the feed screw down and threading it for a nut to retain the handwheel, it is almost done....
Ok, so here we have the bushing, micrometer dial and handwheel. The handwheel and micrometer dial have been machined to take the bushing, but the handwheel also has an o-ring recess for the dial to ride on.
View attachment 503758
Next up, the bushing has been fitted to the upper bearing race washer and fixed to it. then we have the retainer cap, dial and lastly, the handwheel.
View attachment 503759
Here we see the "basic" layout of the cross-slide feed screw with bearing race washers ("A") in place (minus bearings), retainer cap ("B"), Dial ("C") and handwheel ("D")
View attachment 503761
Here we see the end of the bushing spacer that is affixed to the Outer (upper) bearing race washer as it passes through the retainer cap. Note how it protrudes a little?
View attachment 503762
The Micrometer dial seats over that bushing spacer....
View attachment 503763
Then the handwheel fits onto the outer end (it will be retained by a nut) of the feedscrew shaft.
View attachment 503764
So, how does that all work then?
Well, the bearings are kept in place courtesy of a shoulder, the bearings being fitted either side. This arrangement is then enclosed within the outer end of the carrier boss which the leadscrew passes through and closed using the retainer cap (item "C" in the above photo).
With that all in place, the micrometer dial is seated over the spacer bushing, followed by the handwheel and here is the interesting part.... The handwheel locks against the outer-end of the bushing spacer but NOT clamping onto the dial, courtesy of, give or take, 5 though of clearance.
Sounds complex, but it is relatively simple. In short, everything is captured.
Once I finish the leadscrew, I will put a full set of photos up with the carrier boss included as that carries a drawn cup needle roller bearing.
I have intentionally been taking my time with this and thinking through each and every stage of the design and build process, often changing things to make them less complicated to turn, make the assembly easier, or to simplify or improve the design. Whilst it is almost complete, there are still a couple of things left to finish, such as shortening the handwheel end of the feedscrew shaft, as well as run a thread onto it for the retaining nut amongst other odd jobs.
Having a handwheel on the lead screw is something that is part of my "Tranche 3" (and supposedly final) set of planned upgrades to my 7x (along with fitting a DRO, probably an ELS, possibly a motor upgrade to 1.5 HP, and a better control box with the hi/low gear lever moved to the front; I rather like the look of the shape of the Colchester Bantam headstock, so I may make something out of aluminium plate that takes design cues from that).
Currently doing "Tranche 2", which is mostly about rigidity improvements based on Steve Jordan's upgrades, plus a cast iron toolpost plinth as an alternative to the top slide.
There's a "Tranche 2.1" (need some phospor bronze square bar stock for that, and to get the mill trammed) and a "Tranche 2.5" too (getting some bearings in to the carriage, cross slide and top slide handwheels) but I need to get back to making some actual chips on this thing so they can wait until I've done a few more 'apprentice' projects.
There are quite a few of your posts that I will be referring back to as I carry on, so keep 'em coming