adjustable Go/No Go guage for spindle turning

If there are any real metal workers here, please close this thread and move on, strictly amateur hour here

So I'm doing another project and found that it sure would be handy to have a go/no go guage for lathe turning that was slightly more adjustable than a box wrench (that and my box wrenches kept getting lost in the sawdust). I had tried using calipers, but the pointy ends make that a no-go when the lathe is turning so they are slooow. After thinking about it for a while I decided to make one. Features desired were:

• multiple settings in one tool
• Easy to adjust
• can be used with the lathe on to part to size

What I came up with is basically a set of sliding jaws made from some cold rolled steel form the borg.

Parts:

• 1 piece of cold rolled steel about 8" long, 3/4" wide and 1/8" deep for the body
• 1 piece of cold rolled steel about 10" long, 1" wide (3/4 would work but 1" is easier) and 1/8" deep for the jaws
• 4 machine bolt, I used M8 about 1/2" long because thats what the borg had with matching wing nuts
• 4 wing nuts and washers to match the machine bolts

All told this cost me $15 and I have a lot of cold rolled and some washers left over.

This is actually doing the second half of the body so you can see what the desired outcome is on the left here.

First scribe a line down the center of the piece you're going to use for the body. Doesn't have to be exactly on center, but moderately straight is desired.


Then center punch a bunch of dots down the line and drill it out. I used a drill bit just slightly under the size of the machine bolt (like 1 step down from what you'd use if you were tapping it).


Once its drilled you can either use a small round file or a cold chisel to remove the bulk of the webbing between the holes. If you use a cold chisel leave webbing every so often like in this picture to keep the sides from spreading apart and then remove the remainder in a second pass being a little more gentle on it.



Then its file file file. I started filing with the side of the file to open up the remainder of the webbing.


and then switched to filing flat. Your goal here is to get it pretty flat and straight and just barely wide enough that the machine bolt can barely fit and slide from one end to the other.


Now the body is done (the right side looks the same as the left side in the first picture) its time to make the jaws. First measure off about 2" from the 1" material, scribe and hacksaw it off. The length doesn't have to be exact, but they should all be close to the same.


Now use the inside slot in the body to scribe the jaws. Line one side up with the end of the jaw and scribe. Then rotate 90 and line the body up roughly with the middle of the jaw and scribe again.


You should end up with a little square with lines coming off of it like below. The center punch the middle of the square.


Drill the spot you center punched out and then tap it to accept the machine bolt. Then hacksaw outside the lines like below to make the wings.


Now you need to bend the wings over a bit (basically so they stick out about 1/8" inch). The wings slide in the slot in the body so they eventually have to fit. Ideally at this point they are somewhat over sized. For bending the first wing over I just clamp it in the vice and use a punch and a hammer, the second one is tougher because the first is in the way so I clamped it around a piece of hardwood and repeated the process.


(continued next post)

Here is one of the wings completed. To go from the mangled mess I started with in the previous step to this fine piece of work, I basically filed a little here and there and fit it to the slot holding up to the light to see where its not going. I found that putting the machine bolt in place near the start of the filing here helped keep it aligned. Part of your goal here is to also get it square to the body. If its out of square and getting close to fit you can gently adjust it by clamping the wings into the vice and tapping on the end of the jaw to bend them in concert.


And finally here are two shots of the front and back of the completed contraption. I put a washer under the wind nuts, if they had a splayed base I don't think it would be needed.

I also eased the ends of the jaws so that they wouldn't bumpity bump when held against a workpiece on the lathe.





How does it work? Pretty well, I filed one of the wings down to far so I need to make one new jaw as the current one wants to cant out a smidge under pressure. Other than that, its pretty spiffy.

It don't have to be pretty if it works, Ryan! Whatever it is...

Billy Burt said:

It don't have to be pretty if it works, Ryan! Whatever it is...

Click to expand...

Heh, so maybe I should explain that part

So what you do is hold this to the back end of a spindle while you're turning it on the lathe and parting it with a parting chisel. When you hit the correct size it slips over the spindle (the go part, the no go is when it doesn't slip over) and you stop. So for instance I wanted a 1/2" tenon on a piece so I pressed the jaws together around a 1/2" drill bit and then tightened the wing nut to hold it in place and its set to the size I want.

People have come up with all sorts of things for this like:

• The Galbert Caliper
• Custom go/no go gauges - the first one he uses at 0:38 to 0:44 does exactly the same thing that this does except mine is adjustable to any arbitrary size.
• using a box wrench to do the same thing as the above
• I can't find it right now but woodcraft (and others) sell a "tool" that is essentially a series of cut outs in a piece of steel so they slip over the piece at the right size, it costs more than mine altogether and only fits specific sizes.

Very cool and very inventive, Ryan.

Cool! See? It works!