Compound lock so I can use tool presets in DRO.

[737mechanic]

So I got my DRO set up and it has the ability to have 18 tool presets which would be very handy except for the fact that after setting the presets if the compound gets moved at all the presets are worthless. I thought about adding some kind of compound lock that would lock the compound in a exact position that way even after using the compound I can position it back to its preset position and have the presets in the DRO be useful again.

Am I thinking to much into this or does this make sense to use.

[Dave_C]

Unless it works different from the DRO's I have, and it might, the presets for each tool are established from the first (Master tool).

So if you set the first tool to 1" diameter (assuming you are in diameter mode and not radius mode) then you put the next tool in but you make it touch the work just like tool #1 did. Now set the offset for that tool and so on down the line. And because tool holders and tool angles are different it will record the offset for X and Z.

Then in the DRO you will have to tell it what tool you want to use and it will change the offset to match the tool. The intent is you can make a part using multiple tools without having to reset your zero. (All lathe speak as you said Lock the compound, I think) And yes, you would need to lock the compound in a fixed position!

Does any of this sound right?

Dave C.

[737mechanic]

Yes Dave that is exactly what I am talking about. The problem I see is once the presets are set the compound will not be able to be moved or all the presets will be off by the distance the compound was moved.

BTW I keep my compound at 29 degrees so I was trying to come up with a way to add a positive stop and lock system that way when I want to use the presets I lock the compound in its positive stopped position which would be the same position it was in when I set the tool presets but when I need to use the compound I could easily release the lock and move the compound and when done with the compound I could put it back to the same exact position so the presets are accurate again.

[Dave_C]

There might be another way to look at this:

When and how do you setup your starting zeros each time you fire up the DRO? Even if you move the compound, once you set the first tool would not the rest of the tools then have the correct offset?

So what I am getting at is this. If you move the compound to do a thread or some other operation, just put it back reasonable close to where it was and then rest your zeros for the master tool.

Try it and see if it works,

Dave C.

[GlennW]

My compound has a set screw to lock it and I just zero the dial on the compound.

If I need it, I can unlock it, use it, and then just set it back to zero and lock it.

[737mechanic]

GlennW, I also have a setscrew to lock mine but my dial rotates so I can adjust it to a given work piece so there is no guarantee the dial will be set to the same position. I would need some form of physical stop that it would butt up against and then lock it to guarantee it was at the given position.

From the picture below which I found on the internet of the same lathe and compound I have I thought I would make a stop that would allow both the faces of the sliding part of the compound "Arrow 1" to butt up even to the face of the fixed base of the compound "Arrow2" and then lock the compound using either the setscrew or like this guy did in the picture replace the setscrew with an adjustable kipp handle. Of course the compound would have to be at the same angle each time.

[737mechanic]

I see what you are saying, zero the dial before I move it then make sure I put it back to zero. I know me good enough to know that about the time I remember to zero the dial is after I turned it.

[Harold_V]

Am I thinking to much into this or does this make sense to use.

While I didn't use a DRO, it was of importance to me for dial readings to remain consistent, even if I had to use the compound, which I normally kept locked down by tightening the gib. So, yeah, it makes sense.

If you must use the compound, make it a practice to lock it in a common location. You can make a mark on the slide as a reference, where you stop the compound at 0 on the dial. So long as you don't alter the dial setting, you should be able to return to the same place, where your coordinates will not have changed. Make it a habit to ALWAYS stop the slide in the same direction, so backlash isn't an issue. I simply choose to stop in the same direction the dial reads in a positive direction (clockwise).

Harold

[BadDog]

Depending on how it's constructed, you might also use a tapered pin. They can (re)locate things with very good accuracy, but remember to include a means of removal. You could also replace the compound with a "plinth" located repeatably using one or more tapered pins. All you presets are configured to use the plinth, general machining with the compound.

But frankly, I found the presets unusable for my way of working. I simply don't have enough blocks or insert holders providing enough different presentation options. So I frequently find that i need to use "this too", but (often) the lead angle (or something) isn't I acceptable so I need to swivel the tool post or compound to make it work. And, far less often but still happens that I may need to swivel post and/or compound to clear features or setup tooling during the cut.

And then there is HSS, the bane of presets. And though I have a big lathe designed specifically to run carbide insert tooling, I still really like HSS and use it quite frequently. Almost every job really since I have a block setup for doing both ID and OD chamfering on the same block using HSS inserts. Mounted on the position nearest the work piece it's sort of like half a sharp boat hull allowing breaking the edges quite cleanly even on smaller drilled holes up to whatever. Move it to the position near that chuck and it's got a much more robust grind designed to simply provide a clean broken edge, or hog on end to provide a deep "V" for welding. I use that in some capacity almost every job, the exceptions being materials where the grinds or MoMax HSS in general won't work. Bit they get used enough that they are frequently touched up, or even sharpened substantially, and once in a while completely reground. Not that this is really an offset suitable tool, but does provide a good example of HSS in the mix.

In the end I concluded (for me anyway) DRO tool offsets were useful only for limited scenarios where the following were true.

1) Tool blocks and insert holders are quite plentiful.
2) The range of operations is relatively limited. Particularly where you are producing a number of identical or similar parts not suitable for running on turrets or automatics (modest but not huge quantities).
3) You basically never run HSS

[GlennW]

I zero mine when the ends of the compound are flush, (arrows in the pic) or as Harold suggests, make a mark.

Even if I bump the compound handwheel I can simply reset it to zero.