My real question (not well articulated) was whether or not it "sees" the compound's movements; it sounds like they do not, and DRO users keep the compound locked most of the time.
The compound looks like a very nice way to create controlled axial movements. It would seem far easier to bump the compound parallel to the spindle and to use it for small motions than to try to get the carriage to make the same small motion. Just my mill-based experience (perhaps naively) transferring to a machine I am only beginning to understand.
I respectfully disagree: the dials are tricked by uneven wear in the leadscrew (and the DRO is not). Backlash confuses the _operator_ if same is not paying attention.
CAD drawings meet my needs, but they could certainly be simpler if they needed to show dimensions only for the first of such holes. As it is, I end up creating extra dimension layers for my more complicated parts. Two layers are fairly common, usually split among milling and drilling operations. I think three is my record to date.
I'm not advocating that, though I wouldn't mind flying a Trimotor once.
Faster, sure, no question. More accurate? I might want to debate that one. However, it also could easily become a crutch. Had I not mastered scales and dials and built muscle memory to keep backlash from nailing me, I would have been hosed trying to use an RT. I look forward to bragging about the work in question, but I can't do it yet. Titanium space station parts it's not, but I am convinced I am right about practicing the basics.
I cannot yet comment from experience, but the compound looks awfully handy to remain locked. Just a thought from a newbie.
How much do you expect to pay for your next mill? There are various systems which are less expensive than you may think.
For example, the "Shooting Star" BT-2 (2 axis, reasonable for a lathe) currently sells for US$ 599.
Check out:
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(They seem to have changed the readout box since I picked mine up, which may contribute to the higher price than I remember.)
Note the tiny led in the white circle with the word "DIA" under it to the left of the Y-axis display. This is to tell you that you have the multiply-by-two setting turned on.
That is for several reasons. In particular, as you may have noticed, each additional axis increases the cost of a DRO, and you would need two additional axes here -- the feed of the compound's handwheel, and the actual angle at which it was set. Take both of these figures, and a scientific calculator, and you can calculate how far the tool tip moves in each direction -- and add those figures to the X and Y display figures. Or -- add more intelligence to the DRO and let it calculate for you. But remember that unless it is set parallel to the ways, you will get changes in both axes at once.
Of course, you could leave off the angle sensor for the compound, and simply enter the angle manually if you change its setting. Normally, I leave the angle set to 29.5 degrees (the best angle for using it when threading to feed in almost along the flank of one side of the thread) unless I need to cut a left-hand thread, or an Acme thread, each of which requires a different setting to the compound.
But the other thing is that the sensor for the compound's motion would be bulky enough to get in the way. The cross-slide and the longitudinal motions are large enough so the system has sufficient room, but one on the compound feed would be quite awkward.
This is what a micrometer bed stop is for. It clamps to the bed, and stops the motion of the carriage at a preset point. You can change the point (in thousandths of an inch) by adjusting the micrometer thumbwheel. So -- you adjust the micrometer and then use the normal carriage handwheel to move the carriage into firm contact with the stop again. And your setting is absolute position based on the movement of the carriage. The compound reset to parallel the ways is at the mercy of any motion of the carriage. And -- it has a limited travel. You can stack a bunch of gauge blocks between the bed stop and the carriage to define longer distances, but there is nothing you can do with the compound to extend its range.
This kind of precise motion is seldom needed.
Wait until you have actually *used* the lathe for a while before deciding what you need.
So -- start using your lathe, and then come back for other suggestions.
The sensors in the mill are part of the DRO, not part of the leadscrew/nut/dials assembly.
Backlash results in positional errors both depending on the direction of approach, and in absolute errors when the leadscrew is not able to move the table to the position which the dial numbers would suggest.
The cross-slide leadscrew on my Clausing when I first received it was badly worn -- enough so that it looked like this in the middle (use a fixed pitch font like Courier to avoid distortion of the ASCII drawings.):
/\__/\__/\__/\__/\__/\__/\__
Instead of like this as it should _ _ _ _ _ _ _ / \_/ \_/ \_/ \_/ \_/ \_/ \_
The total backlash was 0.070" (out of a total of 0.100" expected motion for a full rotation of the leadscrew. Since the leadscrew was only this worn in the middle, you could expect an error of about 0.035" in the middle if it was zeroed at the unworn sections near the end. And in reality, since the majority of the wear was during power crossfeed to part off workpieces -- most other work was done by a bed turret, the error on feed was probably significantly greater than on the return as would be used when boring the ID of a workpiece.
But a DRO would be measuring the actual position of the cross-slide, not what the leadscrew dial thought it was commanding, so it would be free of the error and the lathe would be better used with the DRO readings and with a blank dial until the leadscrew was replaced. (It has long ago been replaced, of course.)
O.K. And these depend on the accuracy of the leadscrews in the absence of a DRO.
Note that backlash in a milling machine's worn leadscrew can also result in serious damage to the workpiece and/or the cutter. If you are climb milling, the cutter can pull out the backlash resulting in too strong a chip load on the cutter.
Time to turn into the ass I was trying to avoid being...
YES more accurate. Unless you do this for a living or have done if for a hobby for longer than a week and a half, you don't have a lot of room to be throwing statements like that around
However, it also could easily become a crutch. Had I not mastered
Keep that thought in mind...the newbie part, that is
I've got around 40 years doing this stuff...from things I've read from Gunner and DoN, they each have at least that much or more time in this. AND this what we do for a living...so between the three of us, we're talking about 120 years or so of collective experiance.
I'm not saying that we have all the answers, but you barely have the questions and you're tell us how things actually are. How you do that, I'm not sure.
Exactly. Some lead, others follow ever so slowly, ie SB. >
My Monarch (1958) has a crossfeed dial graduated 0.000-0.500" on a 4tpi feedscrew as well as graduated 0.500-0.000" for internal boring. Apart from cosmetic differences, the dial has the same graduations as a local 1944 Monarch of the same size. However I imagine my dial is a lot bigger than yours as it's 5" in diameter, so maybe Clausing costing clerks had a say in your dial and the subsequent graduations? :-) >
No. I have a 2" DI mounted with a magnet to the carriage. I use that a lot. If I were to put a DRO on my lathe, it'd be first on the carriage and thence on the tailstock as for drilling. Won't happen anytime soon if ever.
I know of the Renishaw probe. I just use a centerfinder. I'm not in any hurry. The mission statement in my shop is NIU, HFIJ1. (Nothing Is Urgent, Having Fun Is Job 1)
Is a pencil a crutch, or is a stick and a tray of wet clay the proper tool?
You can be a purist, and work on your chi, or you can turn out work.
Shrug
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Ive only been doing it for about 12 yrs actually. Not even that long..but Ive spent 12 yrs as a machine tool mechanic, diagnosing, fixing, setting up and teaching folks to run both manual and CNC machine tools, and trouble shooting metal cutting machines when they take a shit, or stop making accurate parts. Or worse..making good parts ALMOST all of the time....
Then there is the home shop..shrug
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Plunger style long travel dial indicator works just hunky dorry on a tailstock. And pretty well on the cross slide also.
Using a 3-4" long travel indicator, put the punger against the ass end of the drill chuck in the tailstock ram. Now you have a mechanical DRO. Hold the indicator to the tailstock nose with a magnet, or a hose clamp.
The same can be done with the cross slide. And the carraige.
And IS done every day in machine shops all across the planet.
Its not rocket science
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
That looks pretty good, and the price is better than what I have seen elsewhere. Others might quickly point out that there are reasons for that. I will probably contact them about their custom instrumentation to see what they do on the medical front.
Understood, but it should not be that hard to bump it with an indicator.
Thanks for the look ahead.
True, but so would be the motion of the toolbit, so a stop on the carriage has the same limitation, right? If anything, it seems that a stop on one side would exaggerate any misalignment, but I will have a look. I have not found one yet, but it should be easy enough to make for what I have in mind, which is (more or less) cleaning up a shoulder at a desired location relative to another feature. For relative motion, a fine thread and a dial indicator should do the job.
Noted. It would be useful only for small adjustments.
Got it.
We might be talking about different things, but I learned a lot regardless.
Of course, but I'm getting a lot out of this. The real purpose is to tease out what I might have wished I had asked six months from now. My mill purchase was a mix of homework and some luck. I tried to take some of the chance out of this purchase and was mislead. I see no gain (and a lot to lose) by punishing that just for the sake of it, but I did need to get a crash course in lathe work in order to make an informed decision.
It doesn't work unless you have a carriage micrometer stop or lengthwise dial indicator (or the work is so short you can lock the carriage to the ways), and then you don't need to do it.
Plan the job so you can always measure. I leave a zero reference somewhere, usually the faced-off right end of the bar even if I'm going to shorten it later.
I set the compound at 29 degrees for threading and leave it there. Any time you turn the compound you have to realign the toolpost as well or you'll break your parting tool, and then you need a long axial or radial surface which the workpiece may not have.
On my lathe the compound handle hits the tailstock when turned parallel to the ways. I've set it to 5 degrees a few times so the compound dial effectively reads 0.0001" infeed, although shaving off a few tenths is difficult. 5 is less than ARCSIN(0.0001) but minus errors are easier to fix.
***When the compound is at 29 degrees for threading the tool moves axially slightly less than half the compound travel. SIN(30) =3D 0.5. Really this is all you need to cut a shoulder accurately.
The cutting diameter changes but you shouldn't make sharp inside corners because they concentrate stress. I either countersink the part that fits against the shoulder or add a slight rounded undercut. Ball bearings are countersunk so the shoulder they seat against doesn't have to be perfect all the way in.
But you can arrange for the cutting pressure to hold the mating surfaces of the nut and screw in contact. Think through manually cutting a window, and you will see that is precisely what happens.
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