As part of my screwing around with the lathe I wanted to turn some drawer knobs. Not only for the experience, but because I wanted some for my shop cabinets. So I searched up a quick "knob turning" set of instructions, this one from Wood Magazine, and tried it out. First step, make a screw chuck. mine is in the pic and turned out much as they directed. Then I mounted a 1 7/8" square x 1 1/8" thick blank (cherry) and set out to make a knob. But the blank comes off the chuck. Not unscrewed, but at first the screwed tore the hole out and the blank fell off. I drilled a much smaller hole on the opposite (this is practice) side and tried again. Same result, although the blank  appeared to be secured quite tightly to the chuck. I was taking very light cuts, first with a carbide rougher, then switched to a small spindle gouge for the second attempt. The screw I used is a #8, and it protrudes from the chuck by 1/2".  I'm trying to turn face grain knobs which does bring up another question. Wood said to round the face grain blank using a spindle roughing gouge...I thought that was a big no-no. Roughing gouges and faceplate turning are bad juju.

 Back to my question, how do I make a screw chuck to turn knobs.....at this point the Wood instructions seem to be suspect. Do I just need a bigger screw in my chuck?

Edited April 23, 20242 yr by Fred W. Hargis Jr

Since I don't turn (or have a lathe for that matter) THIS would be my suggestion.

Second question first. It's OK to use the spindle roughing gouge to round the OUTSIDE of the blank. I would knock off the corners of the blank with the bandsaw first just to save time and reduce the chance of tear out.

 

Couple of things you can do to keep the knob blank in place once it's screwed onto the shop made chuck. A bead of hotmelt glue around the interface of the blank to chuck.  Double sided sticky tape between the blank and screw chuck.

 

It seems counter intuitive but turning faster is better. I'm guessing here, but are the blanks tearing out as you are making them round, rather than actual shaping? If so, faster turning has the affect of reducing the amount the tool moves "into the air" between the blank corners as they travel past the cutting edge- if that makes sense.

I was running about 1800 RPM and trying to round the blanks. I'll repeat the process with either the tape or the hot melt as well as knock off the corners. I'll speed things up as well.

Personally I would rather turn end grain. But that aside the more surface of the bottom of the blank contacting the chuck the better. More contact creates stability and the extra surface can be turned off when the rest of the knob is done.

 

Now as to my preferred way  is to chuck the blank normally and turn away.

Cutting from the front rather than banging the corners off from the side helps too.  Thus video shows how to cut the corners off.  Hope it helps,

 

 

He makes it look so easy......

He does..... 

Success!!! (sort of)...using a combo of things mentioned above I was able to turn one knob. I rounded the blank in the scroll chuck as Raffen did, and put double coated tape between the blank and screw chuck. I have to admit, the tape is a little tedious....I may try it again without it, then maybe the hot glue if I need to do so. Of course there's another trick I need to learn: turning several of these that look somewhat alike. Lessons for later today. Thanks to all for the help!

1 hour ago, Fred W. Hargis Jr said:

Of course there's another trick I need to learn: turning several of these that look somewhat alike

Can you make a profile template gage from heavy card stock or cardboard to get close?

I do have a profile gauge that's too large for these, but I could use it to make a cardboard template; good idea.

1 minute ago, Fred W. Hargis Jr said:

I do have a profile gauge that's too large for these, but I could use it to make a cardboard template; good idea.

A blind squirrel finds a nut once in a while or in my case a donut.

If you made the chuck nearly as big as the knob the blank would have more purchase and stability when it was screwed on.  Light passes would be needed but it is doable. 

3 hours ago, Fred W. Hargis Jr said:

maybe the hot glue if I need to

I use it occasionally but it can sometimes be a bugger to get off the wood. Alcohol can help loosen it.

Well, it turned out the tape wasn't as much as a problem as I though. I had a heck of a time cutting a piece small enough and then cut a hole for the screw to put it on the chuck. But when i turned the first knob and removed it, the tape stayed on the chuck, and I turned a second one using the same tape...I was thinking I would have to replace the tape for each knob. Now I'm thinking that if the tape does come off, I may try a piece of PSA sandpaper on the chuck and see if it helps. I do have another piece of maple I could use to make a second screw chuck and give it a bigger "footprint" like Dan suggested.

OK, I had a bit of recovery. I was able to get 11 knobs completed and while they don't match the perfection you accomplished turners get, I'm calling it a win. I had 14 blanks for this out of the piece of scrap I cut up to make them, but 2 of them had some good size chip out during the rounding process that made them unusable. The third missing one got sucked up in the DC and i can't find it in the ducts or the dust bin..it'll show up someday. The remaining 11 went very well, I got the shaping close and started using calipers to set the diameters after the first 3 making them a little closer in size. I did less well on the detail on top of the knobs, the rings aren't cut to the same depth, and sometimes the diameters aren't as close as I would like. They're mounted on a board so I could give them a coat of garnet shellac for the finish. But the whole thing was enjoyable as well (more importantly) as a good learning experience. I'll be doing more but some other things are at the top of the list for now.

Love 'em Fred as well as you sharing your journey. Helpful for current and future aspiring turners. Thanks!

6 minutes ago, Fred W. Hargis Jr said:

The third missing one got sucked up in the DC and i can't find it in the ducts or the dust bin..it'll show up someda

Good thing you had shoes on. While you're checking, you mind looking for a few #2 yellow pencils I'm missing? Also I seem to be missing a couple of donuts.

They look great Fred.  As a reminder your mechanic wrenches make nice rigid calipers for such endeavors.  They can be a bit wide sometimes.

Well done Fred!