Christmas rush is over, the mad house is now quiet again and I was itching to make a mess of my recently cleaned up lathe. I had run across a reference on the net to something called "lathe alignment buttons". Do a search you will find a few references and photos.
In a nutshell, lathe alignment buttons are simple steel buttons that fit one on on the tailstock dead center point and one on the spindle dead center point. You bring them together and then measure the diameter across the two buttons - the difference from the nominal diameter of the buttons and where in relationship to circumference of the button will tell if your spindle and tailstock are in alignment and if not in what axis or axis'.
As a simple afternoon project I thought I would make a couple and give them a try, I always like to try some of the old ways of doing things and I think these "lathe alignment buttons" have been around a long time. You won't find many references to them on the internet and at that only with reference to gunsmithing.
Now, these things are dead simple to make. There are only two critical dimensions - the nominal outside diameter of each piece and the tapered hole (think center drilled) which fits on the dead center pointy ends. Otherwise anything suitable is just fine.
I started with a piece of 1" leaded steel and turned a sectional to the nominal size - seems the most common nominal size is .900", so that is what I choose. This was a good exercise is aiming for target diameter and hitting it. I managed to get to .9005" - just a wee bit larger so that I could finish it to size later. Sorry, no in progress pictures - simple pictures of just turning metal can be pretty boring.
I laid out each button to be 1/2" in length (notice the dimension 1/2" not .500" - the dimension is not critical). Now I turned the end to 3/4" diameter about 5/16" long so as to leave a portion about 3/16" of the nominal diameter intact. Sharp edges where broken with a file. The end was carefully center drilled and the button parted off to length.
Two buttons where made and the 5C collet chuck mounted up on the lathe. Each button in turn was put in the 3/4" 5c collet and the end faced off and a through hole of 1/8" drilled through. The through hole is not necessary, I only did this so that I would be able to put the button on a piece of stiff wire later on for the "treatment". Sharp edges where broken with a file and the nominal outside diameter again measured and the piece carefully brought to size with a fine file - spot on, both pieces now measure .9000" across the critical diameter of the piece.
"The Treatment" - whenever I make small bits of tooling I more often than not give them "The Treatment". Shiny metal looks OK but to keep oxidation in check and give the pieces a bit of colour I do the following: mount the piece on a bit of stiff wire and start heating with a propane Turbo Torch (I use the BIG burner head). Once the pieces are starting to get hot I dip them in a can of synthetic motor oil which gets the smoke a going. I use synthetic as it is less likely to burn (not all synthetics are pure synthetics, many use a mineral oil base). I don't know if the use of the synthetic helps or not, it is the only type I have ever used for "the treatment" so why change? Continue heating the pieces and quench again after they are quite hot, repeat, and then final heat to red heat and quench once more. Leaded steel does not contain enough carbon to harden nor does something like 1018 CRS. This "treatment" puts a nice blue-black oil/oxide colour/finish on the pieces. It is not as robust as parkerizing or gun bluing but is quite utilitarian. I have never had a piece treated like this take on any rust in the shop whereas many of the pieces I have treated with the common gun bluing solutions ended up rusting in the groves of the threads and in sharp corners despite my best efforts at washing and oiling after treatment.
A quick measure after the treatment shows that the nominal outside critical diameter of both pieces is now .9002".
I tried the buttons on my lathe but jury is still out. I just cannot get them to function as expected; there is too much play. I suspect that the "center drill" bit is off and does not match the dead centers of my lathe very well. I will have to ponder this ponderable for a bit so that I can come to terms with my observations. In any case it was a pleasant way to make spend an afternoon making a mess and giving something different a try. Sorry no picture of the buttons in place on the lathe.
Pictures, pictures, pictures. Well, only two pictures actually. First one shows the two finished buttons in their naked state. The second picture shows the buttons after "the treatment".
cheers, Graham in Ottawa Canada