The Home Machinist!

Just finished adding a Trav (A) Dial to my Craftsman 12"x 24" lathe, and thought I would share some pictures in case anyone else was thinking about doing this. I was very lucky to get this one at a great price, wish I could afford to put them on all my machines. Love keeping my toys old school, without DRO's, since I do not make a living with them.

I've got a DRO, and I would love a trav-a-dial, if I could find one that wasn't (IMO) crazy expensive. Looking at a DRO is nice for the cross slide, just dial in the cut (following normal proper practice). Much easier to set zero, then work in increments (and re-zero if convenient), or figure out how far you are from your target size and key that in and go (allowing for flex). Much easier than to try to figure out exactly where your next cut needs to be on the dial relative to achieving desired size. But on long travel, other than for final cuts on shoulder steps or faced lengths, the DRO is less useful. Hard to track running digital numbers as you are approaching, say, an inner step or bottom. Tracking and predicting the timing based on an analog arm sweep is SO much easier. Perhaps as DROs move to more LCD or similar technologies they will incorporate a digital depiction of an analog sweep with a few different modes for referencing for how you are applying the DRO values. That would be sweet...

In any case, very nice work, and congrats on the new upgrade!

Excuse my ignorance but what does a Trav A Dial do ?
I'm guessing that it gives you a numerical reading of carriage travel ?

It's like an infinite dial indicator for the carriage.

What does it index on?

It doesn't really. It's got a kind of gear that tracks along the side of the front way. Surprised me the first time I saw one, but apparently they are quite accurate when adjusted correctly.

Wowzers! I'm particularly impressed with the custom fit. It took commitment to remove and basically strip the apron for the modifications, in order to retain the thread dial. That side of the flat way is really straight and true.

My first thought was that maybe it used the lead screw, but that didn't seem like it would work; a gear makes sense.

It's actually a wheel with a convex face that runs against the side of the way.

The reason that it is convex is that you calibrate it by tilting it.

If it is perpendicular to the way, the largest diameter of the wheel rides against the way, but if you tilt it up or down a smaller diameter rides against the way, which alters the reading for a set distance.

I have one in a box...somewhere...that came with my lathe.

spro wrote:Wowzers! I'm particularly impressed with the custom fit. It took commitment to remove and basically strip the apron for the modifications, in order to retain the thread dial. That side of the flat way is really straight and true.

Thanks for the kind words, figuring it out is half the fun!

I remember the convex surface and tilting it to calibrate it, but I seem to recall it's got vertical/lateral lines/grooves along it's circumference. If my memory is correct, describing it as a kind of gear might not be right be ideal, but not something I have the vocabulary to describe.

BadDog wrote:I remember the convex surface and tilting it to calibrate it, but I seem to recall it's got vertical/lateral lines/grooves along it's circumference. If my memory is correct, describing it as a kind of gear might not be right be ideal, but not something I have the vocabulary to describe.

It's been 50 years since I used one, but I don't recall any kind of pattern on the wheel. Doesn't mean they haven't tried a pattern, however, as they may have experimented with the concept. Any deviations from a uniform surface could prove a bad idea, as it could alter the true reading.

The time I spent on the machine so equipped was brief, but I learned to like using the device. If it wasn't for the use of flood coolant, I'd have added one to my lathe years ago. Instead, I use a long travel indicator housed in a plastic bag. Works just fine, keeps the indicator dry.

Harold