accurate length shoulders?

[kenc]

Guys, Of course it's easy to set crosslide or top slide to the thousandth, but my old Sheldon lathe has no facility for accurate setting of Z. I don't have a DRO or a travadial, and I usually do it by presetting my micrometer stop to the fraction of an inch and butting up a 1", 2" or 3" gauge block to the carriage, then butt up the micrometer stop and tighten down.
Is there a better way to cut a shoulder to, say, 3.565" length?

[alanganes]

I have the same issue with my old Sheldon. I bought a cheap set of those cylindrical shop gauge blocks for this. Handy for other similar uses as well.

They have a threaded hole in the middle so you can fasten them together into any size stack you need using setscrews. Then just use that the same way you do with your 1-2-3 blocks and a stop.
Works great.

The set I bought was about 30 bucks from Victor Machine Exchange, one of the VP advertisers. Available from lots of other places as well of course.

[Illinoyance]

I used to use adjustable parallels to set the carriage stop. Set them with a mike and use them as spacers. For longer work I would consider using a shaper gauge to an inside mike to set the stop.

[CalM]

I used to use adjustable parallels to set the carriage stop. Set them with a mike and use them as spacers. For longer work I would consider using a shaper gauge to an inside mike to set the stop.

Make a short cut, measure the shoulder.

Then use the compound to feed the remainder.

OR

Cut the end, set the carriage stop using an internal bore telescoping gauge.

Or.....

Is it one or several?

Four inches is a hike if you want to be precise under power feed.
Level of precision comes to play as well.

[Mcgyver]

I do the same as you guys, carriage stop and block, adjustable parallel, small hole gauges. For an earlier lathe I made a graduate hand wheel for the leadscrew, like a myford, its was semi-useful but barely worth the effort. The other nice thing to have are stops for the spindle and for collets, makes getting things to length on multiple pieces so much easier.

[epicfail48]

Recently ive taken to using the Abom method of a mag-back dial indicator stuck to the lathe bed. Makes a pretty good poor mans DRO. Butt the indicator up against the carriage, move the carriage the distance you want the shoulder to be, reposition the indicator to serve as a 0, then run the cut until it hits the 0. For anything longer than the 1" travel of my indicator, say 2.5", ill move the carriage in .75" increments before repositioning the indicator, i.e bring the indicator in contact, move the carriage .75" in, lock the carriage and reposition the indicator to 0, move another .75", so on and so forth.

Works alright for me, if a bit tedious. A longer travel indicator would come in handy from time to time, but before i did that id just as soon hook up a single axis digital scale

[BCRider]

Make a short cut, measure the shoulder.

Then use the compound to feed the remainder.

Certainly for just a few pieces this seems like the easiest option.

[boslab]

Are you on about instances where you stick an indicator on the front of the bed to know where the carriage is, my instructor in the engineering showed me a way of dealing with grooves, 2 magnetic indicators, one each side of the carriage, it was actually very good, maybe adaptable I remember mic the tool, /2, hold the slip guage on the carriage and zero the indicator, do both sides.
You get the general idea I hope, harder in words than in reality.
I definately have to buy another DRO!
Mark

[Dan Dubeau]

I use indicators on mag bases. A carriage stop would work too, but for the ones and two's of parts that I make it's just never worth setting one up. Mag base is quick and easy as I've got a couple hanging from various machines around here ready to go.

[Galaxie]

I made a clamp-on indicator holder that fits a cheap Shars 2"-travel indicator. I typically have that to the right of the carriage and use it to set a hard stop on the left of the carriage. Then if you have a depth-stop inside the spindle or chuck as Mcgyver mentioned, you can do repeat parts easily. The trick is remembering not to move the compound slide after everything is set.

[Paul Alciatore]

1. DRO

2. Dial Indicator on bed

3. If it's just a short shoulder, use the compound

4. Longer distances:
a. Mark a bit short (.030"?) and cut to that mark
b. Lock carriage
c. Measure
d. Use compound for remainder, measuring after each cut

I am sure there are other techniques.

It has always struck me as strange that most lathes do not have any kind of longitudinal scale. I guess that is a throwback to the early days of lathe construction. Most machinists who have any experience under their belts have already come to grips with this and use the lathes almost without any thought about it. It's the beginners who ask the intriguing questions.

[strokersix]

You could use the lead screw by counting turns.

I mostly use the butt end of my dial caliper to set longitudinal distances. Also I have a 2 inch indicator on a mag base configured to slide along the ways (not the working surfaces...)