Question for the No-DRO Crowd

[Gary Armitstead]

Do this exactly like Harold mentioned early on in this thread.

An old fashioned wax tip, colored grease pencil like the grocer used 50-60 years ago, to mark prices on a can. Cut two sides first. One long side and one short side. These are your "match edges". Record the dial readings on the face of the work or on the machine. The "wax lead" is easily cleaned off the work or the machine. Then advance to the remaining sides to complete the rectangle. I always finish using a "climb cut".

My experience for doing this was 45 years in the die sinking trade making precision no-draft forging dies. And we did this on Cincinnati Hydrotels (these are hydraulic, not a straight lead screw. This is because the tables on these machines weigh anywhere from 1000 pounds to as much as 2 or 3 TONS. The die blocks can be as much as 5 TONS. The rectangular pocket would actually form the outside wall of a forging. There can be NO UNDERCUT and an absolutely straight vertical no draft wall! Pockets as deep as 12 to 18 inches! A forged part needs to be able to slide out of the die during the forging process or the dies are PERMANENTLY locked together. Granted this is an extreme case from what the OP asked about, but the process is still the same. Grease pencil and record the dial readings. Still able to get pockets a couple of thousandth accurate to print!

[liveaboard]

That will work for me; a second zero index mark for reverse traverse.
Maybe not super-accurate but good enough for many jobs.

Maybe I'll get a DRO one day. For now I'm on stone age turn-counting, paint marks, dial numbers, and (gasp!) rulers.

[Harold_V]

That will work for me; a second zero index mark for reverse traverse.

That's a little confusing, assuming I understand your intent.

You don't use a different zero mark. If you do, it's too easy to read the wrong one. Just record the proper dial settings in both directions, using the
+
I made mention of. That way you always read the same index mark and stop on the proper dial number regardless of direction of the turn. Really easy if you don't over-run the marks.

H

[rmac]

Thanks, Rich, for yet another idea. I have one question, though. You say:

clamp the table lock and and turn the left handle clockwise (CW) until it stops (locks up) now "0" the dial

When I try this, the locking up of the handle doesn't really happen instantly like you'd hope. Instead, it turns a little bit as it goes from completely loose to complately locked up. So it seems that the zero position will be uncertain by at least a few thousandths. Am I missing something? Also, it seems like this approach would be more complicated on the Y axis because there's only one dial.

-- Russell Mac

[Harold_V]

Thanks, Rich, for yet another idea. I have one question, though. You say:

clamp the table lock and and turn the left handle clockwise (CW) until it stops (locks up) now "0" the dial

When I try this, the locking up of the handle doesn't really happen instantly like you'd hope. Instead, it turns a little bit as it goes from completely loose to complately locked up. So it seems that the zero position will be uncertain by at least a few thousandths. Am I missing something? Also, it seems like this approach would be more complicated on the Y axis because there's only one dial.

-- Russell Mac

That's precisely the reason why I don't use that method. It's just not very reliable, especially if you're trying to hold a tight tolerance, and your point on the Y axis is well taken. Again, the + method works perfectly well and can be as precise as required, limited only by operator skill and machine capability.

H

[Bill Shields]

all of this is why I have been using a DRO for 20+ years.

no matter what they cost -> worth weight in gold.... (well...maybe...depends on $$$ of gold)

[Rich_Carlstedt]

Russell, When I say "locks up" , it's really the point of no backlash ( in that direction)
It normally is distinct but sometimes when you find a sponginess in the handle, it means that
more than just the screw and nut are involved . Like the nut may be a bit loose in it's cavity
or the screw's thrust bearing , but the hard stop is what you want .
Yes, it does not work on Y , however if the backlash is small , say less then .020" , I have seen
machinists put a second hash mark that matches the backlash on the Y Plate, so the normal V at the top , has a second V marker placed with backlash. So clamp the Y and turn CW till you hit the lock up , now "0" out the dial on the V of the Y plate (12 o'clock).( Like normal !)
now turn CCW until it stops , then mark the Y Plate with a magic marker where the "O" is on the dial .
Now when turning CW , you use the top V and when turning CCW , the second V on the left becomes your "o" point
try it and see if it helps

Rich

[Rich_Carlstedt]

all of this is why I have been using a DRO for 20+ years. no matter what they cost -> ...........

No argument there Bill. In 1985 I took over a die shop with 35 machinists ( 2 shifts ) .
The owner didn't want to spend the money but did as I showed him the results
We doubled our production in 6 months ..mostly because all the machines had new DRO's

Rich

[Fasturn]

Cant emagine its too close with no DRO. Just paint with dykem and scribe lines with a height gage. Cut carefully to the lines done. With opti-visors I could hold + - .005 easy.

[liveaboard]

I'm making a bunch of quick change tool holders for my lathe.
The only dimension that has to be accurate is the 82mm distance between two grooves.

With no DRO, I used a micrometer to measure before the final depth cut, adjusting as necessary.
This worked well once I got the hang of it.

Not that I'm glorifying the lack of a DRO; I'm just making do.

[Harold_V]

That's exactly what we used to do in the days before NC or CNC controls, or DRO's. You'll never regret the skills you develop by working that way.

H

[liveaboard]

Thanks; this project is taking a lot more time than I'd imagined, but I'm having fun with the learning curve.