Adding A Graduated Dial To A Compound Rest

PAturner

PAturner

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Hi,
Hopefully nobody thinks I'm posting too many threads. Lots of questions are coming in quick succession as I explore my new (to me) lathe.

The question I have today is can I add a graduated dial to the compound rest of a lathe? And by "add" I really mean add. There was never a dial included in the hand wheel system of the compound- only on the cross slide. Has anyone done this? Can it be done at all?




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usually there is no space to put one if there is not one from the factory. You could pull the handwheel and post a photo of the compound screw so we could see it. A dial could be made but calibrating it may be a challenge. What may be easier would be to add one of the digital scales to the compound and just read it that way. The shorter scales are relatively inexpensive. You could also use a long travel indicator to measure the travel when you need to. a simple angle bracket could be attached to facilitate using the indicator.

You can not ask too many questions!
 
Start out by finding out the slide's feedscrew pitch! Use a dial indicator to measure how far it moves with e.g. 10 turns, divide to get how many thou" (or mm?)per turn - if it's something convenient there'll be other handwheel dials you can modify to fit (a lot have 50, 100, 200 graduated marks) by boring or sleeving to fit the shaft you have.
Beware of the Chinese habit of fitting "something close", I've seen dials graduated 0-100 which actually moved the axis anywhere between 63 and 160 thou"...

Dave H. (the other one)
 
PAturner said:
Hi,
Hopefully nobody thinks I'm posting too many threads. Lots of questions are coming in quick succession as I explore my new (to me) lathe. (snip)
Click to expand...
You cannot get help unless you ask, and there are never too many ideas to choose from, only too few. Mutual support is the purpose of this site.

BTW, I think your lathe is much closer to 100 years old than 50. Please consider keeping it in as close to original condition as possible. You have a piece of history there and they are not making any new ones...
 
Without a picture or two, you will not get a meaningful answer, sorry. But for a generic response. I tried to think back to when I used the graduations on the compound of my lathe. My answer is, I can’t remember the time, much less than a blue moon, that’s for sure. You could note the travel of the compound with one turn of the handle. Then approximate from there…Dave.
 
Years ago, I added a graduated dial to the tailstock feed on my Sears/Atlas 6 x 18. The tailstock screw was 16 tpi so the dial has 62 full divisions and one half division for .001"/div. The dial and index mark were made from aluminum. It was many decades ago and I don't recall how I did the marking but given the odd number of divisions, I must have used the rotary table. 123 half divisions works out to 2º55'36" with a full division being 5º51'13".

Since there is not a nice round number on the dial, I used it by figuring the travel distance in 1/16" increments with the remainder in thousandths. For example, if I wanted to move .350", I would turn 5 full turns for 5/16" plus .037" for the remainder (.350-.313 =.037").

As mentioned above, Asian machines often use the approximation 1mm = .03937" =~ .040" to convert a metric lead screw to inch measure. It can be annoying when trying to travel exact distances but for traverses of an inch or less that you would make with a compound, this error isn't too significant. I use the practice of moving to the nominal position close to my final position, measuring, and making my final adjustment by the dial. At that point, my error would bee a fraction of a thousandth.

How you actually make your dial will depend on your compound geometry but based on the compounds that I have seen, you should be able to work something suitable out. Here is a shot of my dial.
Atlas Tailstock .JPG
 
You could add a dial ,but why? It is not something you would use very often. And you could use an indicator if you need to check movement down the road. When I used to set up turret lathes I would count the turns on the turret stop and would come up within a few thousands of what I needed.
Jimsehr
 
I used the compound feed dial quite a bit before installing a DRO on my lathe.

One example would be for cutting a shoulder a specified distance from and end face or another shoulder. I would set the compound angle parallel to the ways and lock the carriage. I then cut the first face and advance the compound to the second face using the compound dial to indicate the distance.

Another example would be cutting threads where the compound is advanced along the 29.5º angle.
 
The problem with dials on a compound is they are off the minute you put the compound at an angle as in to cut threads.
 
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