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- Jan 22, 2011
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I find them particularly useful in the Z axis of the lathe, instead of using the dial or indicators.
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So...tell me; Why use a DRO????
- Thread starter Tony Wells
- Start date
I set my machinery up to carry out precision machining for small contract work. Four readouts each on both lathe and mill.
I can machine to 0.0002" accuracy with relative ease, once the machines have warmed up, and that is repeatable over a batch of components.
One of the main advantages is that you don't rely on having all backlash taken out of the feedscrews and nuts, as they do direct measurement of machine slides, in fact I haven't looked at the dials on my screw handles since I installed the machinery.
In all honesty, now that my working days are over, they are a bit of an overkill, but knowing that I can drill on my lathe to an exact depth or coordinate drill on my mill to dimensions previously undoable, gives me great confidence in what I am doing, plus it lets me work much faster as I am not continually measuring things.
Getting just basic ones (NOT the vernier scale types, too temperamental and inaccurate) makes life so much easier.
John
I can machine to 0.0002" accuracy with relative ease, once the machines have warmed up, and that is repeatable over a batch of components.
One of the main advantages is that you don't rely on having all backlash taken out of the feedscrews and nuts, as they do direct measurement of machine slides, in fact I haven't looked at the dials on my screw handles since I installed the machinery.
In all honesty, now that my working days are over, they are a bit of an overkill, but knowing that I can drill on my lathe to an exact depth or coordinate drill on my mill to dimensions previously undoable, gives me great confidence in what I am doing, plus it lets me work much faster as I am not continually measuring things.
Getting just basic ones (NOT the vernier scale types, too temperamental and inaccurate) makes life so much easier.
John
It's interesting hearing about folks who can mill and turn to .0002. Most machines are not that accurate but I guess some people are. 
As to DRO's, they are a valuable device on a mill and somewhat less so on a lathe. On a mill with an edge finder, they are very useful in determining the center of a piece, say to drill a hole. Also spotting a hole from the edge of a workpiece. I have a two axis Mitutoyo on my Mill with an add-on digital scale on the Z (spindle) axis. It will give me a depth to .0005. Bolt circle patterns are easily done as well, that is if you can decipher your manual. LOL.
On a lathe, with the cross slide set properly for lathe where each .001 reading gives an actual .0005 movement, it's fairly easy to turn a correct finished diameter. I also like the ability to measure lengths on the Z (long Axis on the lathe).
I don't use the DRO on the lathe as often as I do on the mill. I actually prefer my micrometers.
All in all, if you have a DRO, you will use it part of the time and it will come in handy.
I'm still getting used to the different letter names for the axes on a lathe. It's nice but somewhat counter-intuitive. On each of my DRO's (Mitutoyo and SINO) I got some stick-on letters to change to lathe usage, although I find it easier not to worry about it since I'm a hobby machinist and seldom have any visitors.
As to DRO's, they are a valuable device on a mill and somewhat less so on a lathe. On a mill with an edge finder, they are very useful in determining the center of a piece, say to drill a hole. Also spotting a hole from the edge of a workpiece. I have a two axis Mitutoyo on my Mill with an add-on digital scale on the Z (spindle) axis. It will give me a depth to .0005. Bolt circle patterns are easily done as well, that is if you can decipher your manual. LOL.
On a lathe, with the cross slide set properly for lathe where each .001 reading gives an actual .0005 movement, it's fairly easy to turn a correct finished diameter. I also like the ability to measure lengths on the Z (long Axis on the lathe).
I don't use the DRO on the lathe as often as I do on the mill. I actually prefer my micrometers.
All in all, if you have a DRO, you will use it part of the time and it will come in handy.
I'm still getting used to the different letter names for the axes on a lathe. It's nice but somewhat counter-intuitive. On each of my DRO's (Mitutoyo and SINO) I got some stick-on letters to change to lathe usage, although I find it easier not to worry about it since I'm a hobby machinist and seldom have any visitors.
- Joined
- Jan 22, 2011
- Messages
- 8,031
I'll admit to being spoiled, and having become lazy because of DRO's, but also I must credit them for helping eliminate errors and speeding work up immensely. I was well into my career before being exposed to DRO's and immediately felt that they were more efficient.
On the X axis of a lathe for example, when I rough in a piece, I simply establish the largest OD for the part, by measurement of course, then enter the numerical value of the size I cut. Let's use 4.000" for example. I can set the Z off the face at 0.000, then turn all the steps for features on the part, starting at 3.8750 (or whatever), then down to the next size, and so on. It is accurate also accurate in Z, and leaving appropriate stock for finishing. Same drill for finishing. Once I am satisfied the DRO is "calibrated", it is a simple matter to turn all the finish diameters and lengths by reading the DRO. I don't have to even glance at the dials. As a nod to CNC training, I often leave 0.015 for a finish pass, and after checking that it is indeed 0.015 oversize, take my finish cuts. Or adjust as necessary if it is 0.014 or 0.016.
On the mill, it saves a lot of math finding centers of parts, or moving incrementally versus absolute in either axis. I presently do not have a digital for the Z on the bp clone, but have used them, and they do work.
I don't claim to be able to cut repeatedly to within 0.0002 on any machine, but on an as needed basis, I have one lathe that will do it readily when needed. Just have to pay attention to detail. The DRO on that lathe reads only in 0.002 increments, on diameter, so if I need to get close than that, I do hang a tenths reading indicator on it for those cuts.
Overall, DRO's make a machinists life much easier, and less prone to making simple mistakes.
On the X axis of a lathe for example, when I rough in a piece, I simply establish the largest OD for the part, by measurement of course, then enter the numerical value of the size I cut. Let's use 4.000" for example. I can set the Z off the face at 0.000, then turn all the steps for features on the part, starting at 3.8750 (or whatever), then down to the next size, and so on. It is accurate also accurate in Z, and leaving appropriate stock for finishing. Same drill for finishing. Once I am satisfied the DRO is "calibrated", it is a simple matter to turn all the finish diameters and lengths by reading the DRO. I don't have to even glance at the dials. As a nod to CNC training, I often leave 0.015 for a finish pass, and after checking that it is indeed 0.015 oversize, take my finish cuts. Or adjust as necessary if it is 0.014 or 0.016.
On the mill, it saves a lot of math finding centers of parts, or moving incrementally versus absolute in either axis. I presently do not have a digital for the Z on the bp clone, but have used them, and they do work.
I don't claim to be able to cut repeatedly to within 0.0002 on any machine, but on an as needed basis, I have one lathe that will do it readily when needed. Just have to pay attention to detail. The DRO on that lathe reads only in 0.002 increments, on diameter, so if I need to get close than that, I do hang a tenths reading indicator on it for those cuts.
Overall, DRO's make a machinists life much easier, and less prone to making simple mistakes.
Actually, once your machines are lubed up correctly and warmed up, you would find that it is relatively easy to get within that tolerance repeatably. The Sino units that I use do in fact read to 0.00005", but they are rather difficult to follow at such a setting, so I just leave it on 0.0001" and it is rock solid.
This is the sort of thing where DRO's assist greatly
When you have a lot of them to do
Do your schedule first, then just sing along with the music
You need the high accuracy when you are asked to make nearly a hundred of these small steam valves, and they have to be guaranteed not to leak. All the work is on the internal surfaces of the valve, and on the tip of the needle which was ground up using a toolpost grinder to tenths accuracy.
The finished article
With regards to axis layout on the lathe, I don't bother, it is just too complicated. I just remember which head does what.
The left one is reading in metric, the right in Imperial.
John
The SINO is an excellent DRO for the money. Unfortunately it has five digits to the right of the decimal point. When I set mine up and discovered that this "feaure" is not adjustable, I was not happy. I called the seller and asked him what I could do about it. He suggested that I "put some tape over the digits I don't want to see". That really warmed my heart.
I made a piece out of aluminum, painted black, that covers the last one or two digits, depending upon how many I want to see.
Good luck to all those hobbiests who work to .00001.
I made a piece out of aluminum, painted black, that covers the last one or two digits, depending upon how many I want to see.
Good luck to all those hobbiests who work to .00001.
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The best thing about DROs is that the make machining so easy. No need to count how many turns you have made. You don't have to worry about where zero is. So what if you accidentally spun the wrong handle. Who cares if your old American Iron has .147"slop in the X axis. To boot, the newer systems have capabilities that can virtually turn your worn out machine into a manual CNC. Try out a DRO on someone's machine and you will be immediately converted unless you are just a true Luddite.
Randy
Randy
I have a sargon dro on my 9x42 mill(xy). The display stopped working after I left the machine idle for 3 months. I have a new 3 axis Sinpo kit to replace it. Any references for better instructions fo mounting than came with the kit? The old dro was quite useful on the mill. I had never felt a need for a dro on my lathes. After reading the replies I may have to try one. I noticed 1 machine had 2 dros providing a 4 axis setup. Is this typical?
Joe
Joe
It's not typical to use two DRO's per machine. A DRO is nice on a lathe but I still enjoy doing the work without one from time to time. I like micrometers.
The SINO manual is not very good. The only pages that are useful are the ones on setup since the unit will have to be set up for lathe, mill or grinder, etc. Additionally, what SINO calls "resolution" must be changed for the radius-diameter issue on a lathe. This is done in the setup.
Other than that, getting the scales parallel to the axes is the main thing and little is said in the manual about that. There is a short page on changing the cable from left to right on the scales which is difficult to understand for someone such as myself who used English as a first language.
Good luck.
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