- Time laps
- Time laps
Hello everyone, my posts have been a bit sporadic lately. Im finding it difficult to keep up with everything Ive got going on and the holydays didnt help. Anyway, I hope everyone made the best of their holydays and enjoyed themselves. As far as this bass goes, I dont have much left, as a matter of fact, its almost done! So, as much as I wanted to do this knob thing in great detail, Im going to touch on the important stuff and get this thread up to date (this beginning part I already had typed up, so I left it as is).
Now where was I? Ahh
yes. With the dummy stack turned bottom up (on top of some wax paper), I liberally applied thin CA glue. While letting that dry I turned focus to the brass inserts. Typically, I make wooden knobs with a set screw in conjunction of a soled shaft pot, so a cut of brass tube pressed in the knob is all thats required. I felt the need to do things differently this time, (I wasnt about to go changing pots on my prewired preamp harness) the concentric pots main shaft is a split shaft and the secondary is a keyed shaft.
In the past I have not liked using a set screw type knob on a split shaft, IME Ive found the knob to be less secure, (due to the compression of the split shaft made by the setscrew) prone to free spinning because the screw has worked itself loose and the rotation to be out of balance, (turning in an oval due to the set screw forcing the knob hard to one side of the shaft). Granted, you could say Im just splitting hairs here; the oblong rotation is something you feel more than see and probably wouldnt bother most, but losing a knob because it fell off somewhere just kinda sucks. So heres what I came up with, for the bottom of the stack, (I tried a few things and simple worked best) I got a corresponding brass tube and drilled a small hole in one side. For lack of better words, the blowout from drilling was just enough to work as a key to the shaft and to strengthen it to hold up to use, I simply applied solder from the outside until the blowout was filled. A little needle filing and the fit was very snug yet allowed easy operation. There was a bit more to the insert for the top of the stack, again using a corresponding brass tube and a piece of flat brass stock.
First I clamped the tube in a vice to stand it up right and did my best to cut a slot across the top middle with a dremel cut off disc.
Rest the flat stock in the slot and solder it together.
The idea here is that when the top knob is pushed on, the flat brass stock will seat in the split stopping the compression of the split and allowing the setscrew to tighten securely and should the screw become loose; the knob will still turn the shaft. The first few times I did this I used flux, (seen in pic) which worked, but
too much of the solder wicked to inside of the tube clogging up the corners and stopping the insert from seating appropriately, not to mention a lot of filing. In the end, turning up the heat on my soldering iron was enough; it still needed a little filing though. The top knobs have such a tight fit they probable dont need a setscrew but they will get one.
With that done it was it was time to pretty up the dummy stack. First the set screw, (I got pics of me doing this with the top knobs but not this dummy stack) after measuring for the indent on the shaft, I made a mark and dripped some thin CA glue over it to try to prevent too much tear-out. Then placed it in a vice and drilled an under sized hole. Next I flow thin CA in the hole, with a tap chucked up in the drill press I give it some threads. Now I place it on a small mandrel and tighten it down with the set screw. Of course this small mandrel did not begin its life as such; originally it was a spring loaded pin for a bifold closet door.
Top knobs. Using a clamp jig drilled out for the 5/8 plugs, I followed a similar procedure as before. Starting with a 5/8 forstner to establish a center point created by the pilot point of the forstner bit, and then follow the pilot point with a step bit. Heres where Im catching everyone up, so on with the onslaught of pics. Thats what we all want anyway, right?.
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Heres the dummy stack before a finale sanding spin and applying finish next to the plastic stack that came with the pre.. I was really surprised to see how tall the supplied knobs were, I made mine a little shorter.
WARNING copy and paste in progress. - after measuring , I made a mark and dripped some thin CA glue over it to try to prevent too much tear-out. Then placed it in a vice and drilled an under sized hole. Next I flow thin CA in the hole, with a tap chucked up in the drill press I give it some threads. Now I place it on a small mandrel and tighten it down with the set screw.
In this shot, Im tapping for the set screw.
Top knob blank, CA glue stain, and mini mandrel.
One of the cool features of my affordable drill press, I can tilt the head 90°. So I use it like a lathe (kind-of) when doing these knobs. By no means would it stand up to the requirements of true lathe work, but for simple shaping and sanding it works good. I have done all this in a standard vertical drill press as well, but being able to do this in a horizontal position is convenient, sooo
Ive been toying with the idea of building a tail chuck and seeing what that dose for me (like a true lathe) but I havent yet. FYI, the scrap of ply in front was used as a tool rest.
I discovered some cheap hobby chisels and reciprocating saw blades worked quite well for my needs. Real high tech, I know.
Cleaning up the bottom
Cutting to hight, first I define the cut line with bevealed chisel ( I think thats what you call it)
I introduced the saw blades with the theory of less sideways presser on the drill press and a quicker cut
Once the excess is holding on by a splinter, I snapped it off...
Then shaved it with the little bevealed chisel a bit. Next, I use a pice of 2 PVC, (that Ive cut length wise) wrapped with 100 grit to contor what will be the top end. (its not wrapped in sandpaper in this pic so the radis can be seen better)
Some more sanding up to
I for get 350
3 something anyway; and we get a set of rough knob
Press in the bushings
Redrill and tap for the set screw, more sanding and refining and
KNOBS!
Wow! That took FOREVER
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