Turning Knobs....

[TerribleTim68]

Hey gang, so I mentioned in the What's On Your Workbench? thread that my brother-in-law is gonna drop off a small lathe at some point in the near future. My plan is to learn to turn my own knobs (and maybe other things too, we'll see how this goes).

@Matt Liebenau mentioned that it might be a good idea to get a thread going so we can discuss the process, maybe share some methods, all that.

I'm looking for advice on where to get started (I know, on a scrap piece), a good resource for learning this craft, all that. I'm not much of a book reader, so if there's videos out there you recommend, fire away. If anyone has some thoughts, advice, methods they want to share, fire away!

 

[Matt Liebenau]

Ok. Since I opened my yap I’ll play a little. Keep in mind, I don’t even play a professional on TV and if I’m doing it that way it could very well be a bad idea...

The pictures are spotty because I always forget to take them!

I start out with blanks, usually cut out with the bandsaw. Pretty close to final height. If I’m doing standard Fender P bass style knobs at 3/4” I’ll start out closer to 1” and mark for center and drill a pilot hole for a wood screw. Remember to keep in mind your final knob length when you drill and screw in the screw.

I use several long wood screws that I ground off the threads on the part that goes in the chuck and left enough thread to just screw in the blank. That goes between the chuck and a live center usually with a small piece of wood or pickguard material under the center to keep from poking a hole in the end of the knob. Some of most of these pictures were taken before I ground the threads off of the shaft of the screws.

Turn the blank round. I usually use my roughing gouge and, occasionally, a skew chisel. Keep measuring the diameter. I generally go a little over 3/4” for a 3/4” knob.

 

[Matt Liebenau]

At that point I turn the knob blank around and drill for the recess. On a 3/4” knob I usually use a 5/8” Forstner bit although I have used 1/2” if it will fit over the nut for the potentiometer and / or if the knob ends up smaller. I sometimes use acrylic pen blanks and those often start smaller then 3/4” square so the end up smaller as well but can look real purty! Also, if I’m using a set screw in the final knob I will drill the center hole to 1/4” or 6mm.

If it’s going to be a set screw knob I’ll drill through the knob for the tap on my drill press at this point. I have a piece of 2x6 that I cut a V groove in with the table saw that I use to set the knobs in on the drill press table and drill.

Then I will either tap and insert a Helicoil style insert or tap directly into the wood, run some CA glue down the threads and run the tap through again.

After that, insert knobs go back on the wood screw, set screw knobs go on a 1/4” or 6mm piece of rod in the 3 jaw chuck and are locked down with a set screw to get turned to final size. This is because with all the turning around and drilling center holes you can end up slightly off from the original center, or I can anyway, and this makes sure the outside of the knob is concentric with the center hole. Also, it removes any marks from the chuck. Note: if you use the Helicoil insert make absolutely sure the end of it or the end of the setscrew is not sticking up above the knob and is below the depth of the final size of the knob. Steel screws and steel or carbide turning tools do not like to spin into each other at 3000RPM!

Once the knobs are back on the chuck I trim to final length, if needed. Either a parting tool or small amounts can be taken off with careful sanding. Then round off edges and make the knobs the shape a knob is supposed to be. After that, as with many things in instrument making, it’s sanding and finishing. I’ll sand with the knob in the chuck. Finish depends. I’ve used a number or different things. Oil, CA, Krylon. On the acrylic pen blank knobs I sand and polish just about like paint.

Last step on the insert knobs is to drill for the final diameter for the insert and press it in. I do that at the drill press with wood clamps I made when my process involved only the drill press and a tenon cutter.

 

[Matt Liebenau]

Once you get that far, there’s a blue jillion different things you can do with dots and lines to fancy things up a bit. I have drilled into the top of knobs and filled with colored resin, pickguard material; whatever. Glowy material, perhaps? Your imagination is the only limit.


I’m far from an expert and would love to see what other people do or come up with!

 

[boxerrider]

These are rosettes instead of knobs, but it shows an example of turning on a faceplate instead of using a chuck. Keep your tools sharp. Use a good wood screw - drywall type screws break easily and the wood, with a broken screw in it, gets flung toward your body at a high rate of speed.

Center hole in the back.

Mounted on the faceplate. Design points were measured and marked along the radius.

Marks were extended while turning.

Finished.


Lathework can be pretty addictive. Your friends and loved ones should expect gifts of toy bats, tops, candlesticks, bowls, vases. . .

Enjoy!
Jeff

 

[Rôckhewer]

I turned some knobs.
They were weird... and never saw the light of day.
But it was fun... so I'll share.
They were meant for a somewhat whimsical alien themed guitar. It was a LP shape... so I naturally thought about "top hat" knobs ...
...and how they resemble little space ships. right?
So I bought some stabilized burl knife scales...
And glued up stacks with some sacrificial maple in between.

And turned out some space ships
(In process)

After the saucer sections were done... I wanted to put an a little alien dude riding in the capsule.
So I turned little maple domes and laser etched on it....Balok's puppet.
(Star Trek TOS "The Corbamite Manuever")
Also I etched & inked some alien glyphs for the numbers...
.... but.... the dude's scale was wrong... and it got silly.

So then I decided to create actual capsules...
So I built a small vacuum former... and made.plastic capsules.
Which I intended to fill with fluorescent glow powder.

That's as far as I got on them... then stuff happened.

 

[TerribleTim68]

This is all amazing info, especially the alien ordeal.If I ever decide to make a vacuum former I also know who to call!

Thanks guys, this is a great start!

 

[Rôckhewer]

If I ever decide to make a vacuum former I also know who to call

I'll derail for a sec & tell ya anyway.
... super simple & fun.
It's a flea market toaster oven, some angle aluminoom ...a shop vac...& a short afternoons work.
Build a Toaster Oven Mini-Vacuum Former
I actually made it to construct inlaid wood ...covered in acrylic...humbucker covers.
But that's another story.

 

[StatesideRambler]

Nearly no one builds model airplanes from scratch any longer but when they did they had to make their own windscreens and canopies and nose cones. There are, therefore, a lot of good, basic vacuum forming tutorials on the radio control & scale model forums, and on youtube, of course. The best aspect of it is how simple the rigs can be and give great results.

 

[Matt Liebenau]

Well, those acrylic pen blanks smell awful when you’re working them but they can make some nice knobs. I was originally thinking the white ones for the metallic and pearl white body pictured but then I started to think that might be too much white so I made a few options. I’m leaning towards the black with black pearl pickguard material ones especially since I think I’m going to glue some black pearl pickguard material into the trem spring cavity.

I realize none of the knobs are perfect. I’ll finalize the ones I decide to use.

 

[rudy4444]

My technique for control knobs starts on post #53 HERE. I even tell ya how to make your own carbide insert turning tools!

 

[Beej]

Well, those acrylic pen blanks smell awful when you’re working them but they can make some nice knobs. I was originally thinking the white ones for the metallic and pearl white body pictured but then I started to think that might be too much white so I made a few options. I’m leaning towards the black with black pearl pickguard material ones especially since I think I’m going to glue some black pearl pickguard material into the trem spring cavity.

I realize none of the knobs are perfect. I’ll finalize the ones I decide to use.

View attachment 4484858 View attachment 4484859 View attachment 4484860 View attachment 4484861

Dude those white pearl ones are the bomb

 

[Matt Liebenau]

Dude those white pearl ones are the bomb

Maybe I will use those after all. I think I’d like the ones with the B/W/B pickguard material on the top if they were shorter. Fortunately, that’s not too hard…

 

[Matt Liebenau]

My technique for control knobs starts on post #53 HERE. I even tell ya how to make your own carbide insert turning tools!

Yessir! Used your pry bar / turning tool method to make some of the tools I use.

 

[Staccato]

Wear short sleeves around a lathe?

Why not seek an experienced, in-person mentor to get you way ahead on the beginner learning curve?

 

[Beej]

Wear short sleeves around a lathe?

Why not seek an experienced, in-person mentor to get you way ahead on the beginner learning curve?

Good idea. While we're tossing around advice, maybe check out the entire thread?

 

[Matt Liebenau]

In case anyone is following along with the home game, I changed up my process a bit. I’ve been cutting out the blanks then drilling the recess that goes over the potentiometer nut with a Forstner bit. Then drilling for whichever mandrel I’m using, 6mm, 1/4” or 3/8”. Then I mount the blank in the lathe and turn it. That way there’s no need to dismount and turn the knob and the possible misalignments that can accompany that. The knob stays on the mandrel to the finish. I’m just trying out some shapes here but the middle knob in the last picture is for @postalflunkie. Not exactly a Wal knob but I was looking at some pictures of Wal knobs. I might make a couple of more like it but make the knob a little larger diameter so the recess in the middle seems deeper. I didn’t want to go too much smaller on that part so there’s still some material around the insert. I’m not sure if I like the domed top or a recessed top like the walnut knob. I guess I’ll have to make a few!

 

[Matt Liebenau]

I just realized I never posted these mandrels in here. I found the standard 1/4”-20 one in Woodcraft then, later they also had the wood cutting thread 1/4”-20 and 3/8”-16. I use the 1/4” ones for 1/4” potentiometer shafts that will get a set screw. I also made a couple out of 6mm bolts for, obviously, 6mm pots with a set screw in the knob. The 3/8” one is for knobs that get the insert for 6mm splined pots from Bitterroot guitars.

Drill the blank as though you were tapping that size hole in metal, screw the blank on the mandrel. When I’m done I hold the knobs in nylon jaw pliers and drill to the final size, 6mm, 1/4” or 10mm, which is just larger then 3/8” for the inserts.

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[postalflunkie]

Oooooo! I do like that middle one