View Full Version : South Bend Lathe DRO

10-19-2005, 11:36 PM
I own a 9x24 Model A SBL. Iwas thinking of putting a DRO on it. Has anyone out there seen a DRO on a 9" SBL? Can anyone recomend a DRO brand name? Are they hard to install? Thanks for the help.

10-20-2005, 08:59 AM
Well...for a lathe, note that for the cross feed you probably need at least 0.0002" resolution to get acceptable precision out of it, since any error in the radius measure is multiplied by 2 on the diameter. So you need a high-quality DRO.

Take a look at the Acu-Rite web site www.acu-rite.com (http://www.acu-rite.com) and poke around the documentation. They have reasonably good documentation on installation, which will give you an idea of what is involved. I recently installed an Acu-Rite DRO on my milling machine, and "tedious" might be a better way to describe it than "hard." The Acu-Rite ENC150 scales (what I got) have to be parallel to the travel within 0.005" over the length of the scale, and closer is better. I assume other high-quality DROs have similar requirements.

If you get serious about the idea, investigate www.candomachinery.com (http://www.candomachinery.com) (usual disclaimers). Mike gave me what I think was an excellent price on a custom Acu-Rite DRO package, and he was really good about answering my numerous questions before and after the sale.

Forrest Addy
10-20-2005, 12:32 PM
That a small machine and those scales are bulky when applied to the cross slide. They're usually applied to the tailstock side of the corss-slide. You'll lose some tailstock function because of the thickness. You'll have to extend the quill further if you're to avoid mashing the scale against accumulated chips. Thus you gain a DRO at the expensice of tailstock rigidity abd risk of damage when cranking the carriage back.

I suggest you look for a "skeletonized" scale you can install in the available space within the cross slide. I used the Sony Magnescale in my lathe. Its scale is a magnetically encoded wire and the reader is about the size of a cigarrette filter. I managed to bury it in the cross slide of my 17 x 60 lathe with little difficulty machining the nut to accept the reader. I had to strip my scale components out of a fully enclosed scale unit but now Sony sells just the guts.

[This message has been edited by Forrest Addy (edited 10-20-2005).]

Jim Caudill
10-20-2005, 02:38 PM
Forrest, I remeber you posting some pic's of your installation a few(?) years ago. I think it was on the old Chaski site. You should re-post that on this site or the PM site; I searched for your installation pictures just a short while ago - not to be found. To others, Forrest did a real neat job of mounting one of his scales internally, or something that was very unique. Don't remember what, it was just about the slickest install I had ever seen.

[This message has been edited by Jim Caudill (edited 10-20-2005).]

3 Phase Lightbulb
10-20-2005, 04:00 PM
I installed a DRO on my lathe (QMS 400 decoder and Quality 500 glass scales/encoders). It was a royal pain in the keister because the optical encoders needed to be precisely aligned through out their entire travel range otherwise the display would just stop counting and would need to be reset. After lots of shimming and trial/error I got both scales and encoders working but I should have just bought a better DRO unit that would have taken less time to install.

One problem with my setup is the cross-feed encoder picks up the littlest vibrations so when I start cutting, the DRO display sometimes flickers +/- .0015.


10-20-2005, 07:50 PM
<font face="Verdana, Arial" size="2">Originally posted by 3 Phase Lightbulb:

One problem with my setup is the cross-feed encoder picks up the littlest vibrations so when I start cutting, the DRO display sometimes flickers +/- .0015.


Sounds like my chinese scale is a POS then...The numbers would never move while taking a cut no matter how heavy the cut...Maybe my cross slide didn't move when cutting..dunno...

10-22-2005, 07:00 PM
Thinking about it some more...I wouldn't bother with a DRO on a lathe. Get yourself a couple of long-travel (1" or so) indicators, mount one on the carriage, one on the cross slide, and I think you'll have all the "DRO" you really need, for a lot less money.

One thing about a "real" DRO that I never thought of until I put one on my milling machine: it makes machine disassembly a lot more complicated. On a milling machine it's probably not that big a deal, but I fairly reguarly remove the cross slide on my lathe for cleaning, etc.

10-23-2005, 08:24 AM

I too would be extremely grateful for details of your DRO cross slide scale mounting.
My Smart & Brown has the scale mounted to the tail stock side of the cross slide & it is a damned nuisance, I also need to move the saddle scale to the front of the bed so that I can fit the taper turning attachment. Finding a potential solution to the cross slide mounting problems would certainly move the job to the top of my round tuits list.