Measuring cuts lengthwise?

J

Jmanb13

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Since i'm a beginner here, maybe i'm missing this, but how does one judge a cut along the bed?

I've searched for the answer here, but haven't run across anything yet.

The cross slide and the compound slide both have graduations for cutting into the work, but how would I know how much i'm cutting along the work?
 
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As delivered I guess the short answer is that you don't. However you can add a DRO to the X axis, or you can add a "travel dial" to work with short X axis cuts.

I do lots of accurate short length cuts and have added a 1" travel dial to the the ways. It is adjustable so I can move it along the ways, and it has a built in travel stop, for repeat work.

indicator in workiing location.jpg

David
 
put a DTI digital test gauge on the travel and see if the readings are 1/2 the cut depth or is the actual amount of the depth of cut. on my lathe if I move the dial .010 it will take .010 off the diameter or a .005 depth in the cut. sorry I did not notice you meant along the bed length, I have used a 2" magnetic DTI on the ways to check distance moved.
 
The carriage hand wheel on my lathe has a dial but it is .020'' per mark or .660'' per turn........too coarse for most purposes.
For more precise control, with the carriage locked and the compound set parallel to spindle axis, feeding with the compound will give .001'' increments.
Otherwise a dial indicator on the ways is good for up to 1'' movement.
 
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I have a trav-a-dial on mine (if you haven't seen them, they're attached to the carriage and have a wheel that rides on the front shear, geared to a dial graduated in thou"), they can be a bit clunky on small lathe's and possibly lose some carriage movement, or I can use slip gauges or length rods in the tray on the front way cover in combination with the micrometer stop and stop rod if I want better than a thou".
Depending on the length of cut, people fit dial indicators on bed clamps against the carriage, you could do similar with a vernier / dial / digital caliper?

I did measure a rotation of the carriage handwheel and it's precisely 1.025", so if I could gear it 40:41 I *could* put a 1" dial on it, but I'd only get fussy and want a metric/imperial geared dual dial...

Dave H. (the other one)
 
We usually measure the cut has we do it a mark with a scale for quick measure then we Mic or vernier it to length. I have a long adjustable stop rod that I can use to set stops for doing lots of parts . Of course now everyone has electronics. But in my ancient youth that's the way we worked , print in hand.
 
David S said:
As delivered I guess the short answer is that you don't. However you can add a DRO to the X axis, or you can add a "travel dial" to work with short X axis cuts.

I do lots of accurate short length cuts and have added a 1" travel dial to the the ways. It is adjustable so I can move it along the ways, and it has a built in travel stop, for repeat work.
Click to expand...
I'll look into DROs. However I think I remember glancing at them in the past and I remember them being rather expensive, especially for someone just getting started and tinkering in their garage.

Ed ke6bnl said:
put a DTI digital test gauge on the travel and see if the readings are 1/2 the cut depth or is the actual amount of the depth of cut. on my lathe if I move the dial .010 it will take .010 off the diameter or a .005 depth in the cut. sorry I did not notice you meant along the bed length, I have used a 2" magnetic DTI on the ways to check distance moved.
Click to expand...

Its funny you mentioned this. I actually was looking at the depth of cut yesterday on my cross feed and its measured in actual removed material. So if I move it 1 full turn (0.250), it moves .125" to remove a total of .250 of material. Good knowledge for using it.

Tozguy said:
The carriage hand wheel on my lathe has a dial but it is .020'' per mark or .660'' per turn........too coarse for most purposes.
For more precise control, with the carriage locked and the compound set parallel to spindle axis will give .001'' increments.
Otherwise a dial indicator is best.
Click to expand...

That is a good idea, If I need to be really precise it will definitely work.

British Steel said:
I have a trav-a-dial on mine (if you haven't seen them, they're attached to the carriage and have a wheel that rides on the front shear, geared to a dial graduated in thou"), they can be a bit clunky on small lathe's and possibly lose some carriage movement, or I can use slip gauges or length rods in the tray on the front way cover in combination with the micrometer stop and stop rod if I want better than a thou".
Depending on the length of cut, people fit dial indicators on bed clamps against the carriage, you could do similar with a vernier / dial / digital caliper?

I did measure a rotation of the carriage handwheel and it's precisely 1.025", so if I could gear it 40:41 I *could* put a 1" dial on it, but I'd only get fussy and want a metric/imperial geared dual dial...

Dave H. (the other one)
Click to expand...

I'll look into those trav-a-dials and carriage stops.

Silverbullet said:
We usually measure the cut has we do it a mark with a scale for quick measure then we Mic or vernier it to length. I have a long adjustable stop rod that I can use to set stops for doing lots of parts . Of course now everyone has electronics. But in my ancient youth that's the way we worked , print in hand.
Click to expand...

Thanks Silverbullet! I can understand cut and measure, repeat. However, how would you control the cut to a more precise movement than the carriage wheel? Would I do something like Tozguy said and just turn the compound parallel and use it for the final cuts?

Is there such a thing as a universal carriage stop? They look pretty basic in design, but since I don't have a mill yet, I don't think I would be able to fabricate one to fit over my V ways.
 
I have a carriage stop on my lathes and if I want to machine to a precise length as in distance to a shoulder, I will set the stop up with a spacer equal to the length I want to turn. Then I face off the end and remove the spacer. I can then turn to the stop knowing that I won't overshoot. The spacer can be anything handy; drills work well for short distances. I have some blocks of various thickness that can be stacked. A simple adjustable spacer can be quickly assembled from hardware store parts. Adjust the length with calipers and tighten the jam nut to lock. Works great when making a bunch of identical parts
Lathe Spacer.JPG
 
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