Author Topic: How many axes on a lathe DRO?  (Read 1508 times)

Offline propforward

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How many axes on a lathe DRO?
« on: March 15, 2021, 05:27:30 PM »
Hello.

I added DRO's to my mill last year, and that was a really positive experience (despite the dent in the wallet). So now I'm considering making similar improvements to my lathe.

In researching what is available, and installation methods and such - I am very surprised to find that 3 axis set ups are very uncommon, and 4 axis set ups non existent.

Why is this? I would think that adding DRO capability to the top slide for sure would be useful, and the tailstock perhaps not critical but very beneficial. I do see a number of single DRO installs on the tailstock, but the relative infrequency of adding a scale to the top slide surprised me. Is it just that once you have the carriage on a DRO, the top slide does not get used much, other than setting an angle? I guess I don't use it for very much more than that now, thinking about it.

I'm wondering because a 2 axis set up, even magentic scales, can be had for significantly less money than a 3 axis set up - but I don't want to install a 2 axis set up only to wish I'd bought the 3 axis.

I'm not in a hurry anyway, I can turn to diameters very accurately now, but I would like more accuracy and resolution on the carriage.
« Last Edit: March 15, 2021, 09:21:54 PM by propforward »
Stuart

Offline Dave Otto

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Re: How many axes on a lathe DRO?
« Reply #1 on: March 15, 2021, 06:44:23 PM »
I only have a 2 axis unit on my lathe and have never really had the need or want for a scale on the compound.
An absolute must for me was to have a scale with 50 millionths resolution or one tenth on the diameter on the cross slide. I had one of the CBX units for a while and the .001" resolution was almost a waste of time. I have a Newall readout now, and have been very happy with it.

Dave

Offline kvom

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Re: How many axes on a lathe DRO?
« Reply #2 on: March 15, 2021, 10:48:01 PM »
On many lathes a cross slide slide mount would be difficult if not impossible.

Offline Bearcar1

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Re: How many axes on a lathe DRO?
« Reply #3 on: March 16, 2021, 12:06:18 AM »
Hmmm. It would seem to me that unless one had one of those super expensive industrial lathes with air bearings, anything with more than .001" capabilities would be a waste of money. Now having said that, I must admit that there most likely are such setups out there in a home hobbyists shop. Not mine unfortunately. I am old fashioned and incorporate manual means to measure distances and size.  :embarassed: A lathe really is only a two-dimensional tool. Oh there are attachments and software to run those 3D  attachments available. But at what practical cost to anyone that is using the lathe for purely hobbyist applications or are gunsmithing. SO, it would seem that only two axis becomes truly of any use. OR, a three-axis unit, which is usually a bit cheaper in cost and can be used on other machines should the need arise, and not incorporating the Z option, be the best practical unit to employ.
 :paranoia:
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Jim

Offline Dave Otto

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Re: How many axes on a lathe DRO?
« Reply #4 on: March 16, 2021, 12:21:22 AM »
It doesn't have air bearings but it is deserving of a decent DRO,  :D

Dave

Offline Bearcar1

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Re: How many axes on a lathe DRO?
« Reply #5 on: March 16, 2021, 12:30:30 AM »
That is a beautiful machine Dave, very nice. No air bearings? Whaaa?    Just kidding.


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Jim

Offline Dave Otto

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Re: How many axes on a lathe DRO?
« Reply #6 on: March 16, 2021, 12:31:46 AM »
That is a beautiful machine Dave, very nice. No air bearings? Whaaa?    Just kidding.


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Jim

Thanks!

Dave

Offline Art K

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Re: How many axes on a lathe DRO?
« Reply #7 on: March 16, 2021, 02:32:14 AM »
I don't have a dro on my lathe but would like to add one. Dave I like the idea of one that is accurate to the tenth couse sometimes I'm trying to hold 5 tenths and that is tough. I really can't think of many reasons to have a third dro. Unless single point threading and have the angle set and are cutting the threads properly using the compound rest. Or are cutting a taper? But even so you're measuring a lot and doing the last few passes with the cross slide. A third would seem redundant. Thats my take and I'm sticking to it.
Art
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Offline AOG

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Re: How many axes on a lathe DRO?
« Reply #8 on: March 16, 2021, 02:43:43 AM »
Ill agree on the higher accuracy scales at least on the cross slide. A one thousandths scale means that the closest your going to get in diameter is +/- 2 thousandths. I highly recommend  spending the money on a good scale for the cross slide as a minimum.

My 2 pennies

Tony

Offline AdeV

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Re: How many axes on a lathe DRO?
« Reply #9 on: March 16, 2021, 07:34:16 AM »
I've put a 4-axis 1 micron DRO on my lathe, even though there's no way it will hold that kind of tolerance (nor can it's operator!). In Imperial mode, this means it'll read down to tenths, but the tenths number tends to flicker when the lathe is running, due to vibration; so it was definitely the right choice.

Fitting the scale to the compound slide was a challenge, and in fact I still need to make one minor modification to make it work correctly - the oil wiper cover on the end of the cross slide is about 5 thou above the surface of the compound slide, just high enough that it fouls the bracketry holding the reader & prevents me from swinging it around, unless I take the wiper cover off. It won't take long to fix with an angle grinder, or a file; it just needs the very top lip scuffing off it.

4th axis for me will be the tailstock quill; but I haven't fitted it yet, due to the need to refurbish the tailstock first; the leadscrew nut is worn almost to nothing (in fact, how it's holding up drilling still I have no idea!), and even then it's going to need some crafty bracketry to hold it in a way where the DRO scale reads usefully, but doesn't get twisted, e.g. when a drill bites, there's a noticeable twist on the t/s quill. I'm not 100% sure which part is worn that lets it do that; it's probably the pin that stops it spinning in the t/s barrel.

Anyway - the purpose of the 4th axis was so I could accurately drill holes to depth. My tailstock either doesn't have depth markings, or they're worn off, and more than once I've wanted to drill a hole Xmm deep; or cut a bore to a certain depth, & so on.

One last thing - the DRO I bought was a Chinesium one from a company called Ditron. Nothing but good things to say about them - they shipped it quickly, the price was good (less than 500 for the 4-axis setup), and it all worked perfectly. I do, however, plan to make my own DRO head unit in the future, because I want to be able to link the Y & Z-axis readouts with the compound axis + an angle, e.g. if I've got the compound set over at 45, when I move the compound slide I'd want to see both the Y & Z axes moving. I think this would be ideal for thread cutting, and taper cuts. However, I'm not aware of any DRO head units which will do this..... so currently my 4th axis is in the "laboratory" (er, bedroom) for electrickery experimentation.

PS: Sorry, no photos yet; the lathe is absolutely caked in rust from a job she just did, and looks about 200 years older than she is! I'll take some photos of the installation once I've cleaned her up a bit...
Cheers,
Ade
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I'm just a poor old man. I have no time for law-breakers. My legs are grey. My ears are gnarled. My eyes are old and bent.

Offline Jo

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Re: How many axes on a lathe DRO?
« Reply #10 on: March 16, 2021, 11:50:36 AM »
If you already have a 2 axis DRO then upgrading to 3 axis is expensive as the Display also needs to be upgraded (it automatically combines top slide and saddle)

If you don't have DROs on your lathe...  :headscratch:

Jo
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Daggers

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Re: How many axes on a lathe DRO?
« Reply #11 on: March 16, 2021, 12:05:43 PM »
I fitted a dro kit to my Myford last year it came with 2 axis scales but used a 3 axis dro so later i could update with a third scale if needed.
What i liked about this kit was that the cross slide scale is hidden under the surface. It did require a groove in the cross slide base, but this was a very simple job.

Offline crueby

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Re: How many axes on a lathe DRO?
« Reply #12 on: March 16, 2021, 01:17:54 PM »
If you don't have DROs on your lathe...  :headscratch:
then, I wouldn't be able to make complicated engines like this... Oh - wait, yes I can, and do!

Just means I have to take a direct measurement a little more often and count on the handwheels.   :shrug:

Offline Jo

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Re: How many axes on a lathe DRO?
« Reply #13 on: March 16, 2021, 03:31:02 PM »
Just means I have to take a direct measurement a little more often and count on the handwheels.   :shrug:

Yup  ;)

And don't forget to wear the glasses  :DrinkPint:

Jo
Enjoyment is more important than achievement.

Offline propforward

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Re: How many axes on a lathe DRO?
« Reply #14 on: March 16, 2021, 03:31:54 PM »
To be honest all I really "need" is a bit more resolution on the carriage. It's not like I can't hit dimensions accurately, but whereas it is quite simple to hit within a thou on diameters, turning lengths is trickier. Similarly I'd like some more accuracy on the tailstock. That could actually be achieved by adding a manual vernier scale (for example).

After all this if I do add DRO's I'll likely just make it a 2 scale job, and maybe a single standalone scale on the tailstock.

Interesting to read perspectives. Thanks everyone for your input.
Stuart