The Shop > Wood & Stuff
Banjo Build
S. Heslop:
More fussing with the spindle sander with no luck. I think what I might try doing is cross drilling the spindle and putting a pin in, then making a plywood sleeve of sorts that I'll just glue the sandpaper to directly with a slot to index with the pin. Might make a few sleeves while i'm at it.
I've also got a slight alignment issue that I noticed pretty much after I built the thing, but I didn't give it a whole lot of thought till now. The motor isn't mounted parallel to the rails that it slides on, and fixing that will probably require an almost full disassembly. It causes the spindle to move forwards a bit as it raises up. While I can get around it affecting the work by just switching off the oscillating for a final pass, I doubt it's doing the sandpaper any favours to be heavily pushed into the work each time the spindle moves upwards.
I should've fixed this a long time ago but I tend to leave stuff like this until it's absolutely necessary.
S. Heslop:
Yet more fussing. Alot of time is spent waiting for glue to dry. I've been trying to bore a 20mm hole into the plywood spindle with no luck. Trying to make crappy reamers out of bits of barstock. That works for shallow holes but it's killing the drill and just causing alot of friction trying to do it with something so deep.
I did think for a bit about making some sort of boring tool using a bit of square high speed steel but at this point I should really just go out and buy a damn 20mm drill. So i'm going to do that tomorrow.
It's always these little jobs that seem to take the longest.
(and in all honesty, I could probably just turn the outside of the thing on the rubbish lathe i'd made too, but i'm dead set on doing it this way. Maybe just to prove the sander wasn't a waste of time).
S. Heslop:
Got a drill bit. An auger, actually. I'm still not sure what advantages augers have over anything else (maybe if you insist on using an old bit and brace), but they were alot cheaper and longer than the blacksmith drills. I'll probably regret being so tight when I need a 20mm hole in metal.
But anyways, it made a nice hole just the right size. But now i've got yet another problem with the spindle no longer being in axis with the motor's spindle. My best guess is that a bit of sawdust is trapped somewhere in between but it's a bit awkward to get at to see clearly or clean it. So I've got no choice but to disassemble it. Could also just be a problem with the spindle not being balanced, and if that's the case then there's probably no hope of fixing the problem. Garage is a total mess though and needs a good tidying up so I have my workbenches back. Had another thunder storm so I piled everything off the floor that I didn't want to get potentially wet on the benchtops.
This project is going at a glacial pace. Hopefully I've got everything i'll need for now though and can get back to it. But spending the weekend fussing with the sander has killed alot of my enthusiasm.
S. Heslop:
I've been holding off posting pictures since I thought this whole spindle sander tune-up would be a quick and boring job.
Got the spindle trued up. Not sure how it ended up shifting out of alignment. Maybe the metal settled or something when I drilled that hole through the middle. It was trued up the same way as when I built it, with scraping the mating face. Ended up reducing the runout to damn near zero.
Hot off of that I thought i'd tackle the spindle not being parallel to the rails and... well I've got no easy way to adjust it, so after alot of thinking about which way things needed to move I shaved a bit of wood off the inside of the lower motor mounts (the ones held on by a jubilee clip) and tried shimming them. Didn't expect to get this perfect but I figured I could improve the situation a bit.
And I think when I put the holes in to begin with I must've just gotten lucky with the placement because I could not get the thing back together at all without it jamming up once the jubilee clip was tightened. Spent more than an hour trying to brute force it with various paper shims. Another interesting thing was inspecting the wear inside the thing. The pin that the crank arm connects to to lift the motor up and down has become fairly loose and it'll probably eventually split the plywood. A few posts ago I was patting myself on the back for a good design but I think this is a weak part and could probably do with some fixing up too. A couple of screws might just do the job in holding the plywood together against splitting.
Anyways I'm probably going to have to think up a solution for the lower mounts that makes them more easily adjustable. The alternative could be to make the parts again, and use the spiked ends of the bars once more to locate the hole centers. Perhaps that way is more accurate than I give it credit for.
No such thing as a quick job I guess.
S. Heslop:
Here's what i've come up with. Flat wooden block that another screws into. There's 4 screws so a jubilee clip can fit between them. I forgot to model the slot required. But it should give fairly easy adjustment in alot of directions (screw holes will be enlarged and washers used to give it some play). Shims can also be used for the other directions, and being square it should be easier to guess where to put them and how much to use. It should also be possible to adjust the thing without disassembling it.
I was wondering why I didn't do something like this the first time around, but then I remembered I didn't have a tablesaw back then and this would've been difficult to do well on the bandsaw.
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