Pictures of DRO installations on classic South Bend toolroom lathes?

[rwdenney]

Yes, I got the bend wrong and it tilts up. But the reader is mounted straight and it only needs to be held in one spot. Ugly but I can live with it.

If it proves too weak, I can run a brace over to the taper attachment frame. But so far it seems sturdy enough.

Yes, I could only get the good taps to go in about a half inch, but finishing with the bottoming tap was enough for the screws that came with the scales. A bigger problem was the holes wandered off square in that gooey steel.

I drilled these in my old press—230 RPM. That’s pretty slow for a drill that size, but that’s what that stuff needed. The 350 RPM slow speed of my better press was too fast. Bigger holes tolerated it better than smaller holes.

When I broke the tap, I had to set it aside for a week while I thought dark thoughts. I even bought an aluminum bar 1/2 x 1-1/2 to remake it. But the new drills in the same McMaster order worked better.

Rick “at least the bandsaw would cut it” Denney

 

[rwdenney]

The Z axis is installed and the DRO is operational. (It’s labeled Y axis on the head unit, of course.) It was a LOT easier than the X axis, for probably obvious reasons.

I mounted the tail end as close to the end of the bed as I could without invading the curve of the casting on the end. I will still run out of scale by maybe an inch if I rack the carriage up against the tailstock at its most extreme position, but I keep a micrometer stop clamped in the ways at the end and it will stop the carriage before the reader hits the end of the scale. I could move the reader closer to the head end of the carriage and solve that problem, but where I mounted it is convenient.

Mounting was just drilling 4.2mm pilot holes in the bed casting at each end of the scale and tapping them for the 5mm x 0.8mm screws that came with the scales. I like cast iron.

Aligning the scale was not made any easier by the fact that the scales are extruded aluminum and not machined straight. But I found a position that got it without ten thou over its length both horizontally and vertically.

I used a couple of the aluminum brackets that came with the scales to mount the reader.

The bracket mounts to the back of the carriage adjacent to the bracket I made for the X axis reader. They are tight against each other and will help keep each other aligned. But the aluminum and steel combination is butt-ugly. Perfect for this lathe.

Calibrating the Z axis is a thousand times easier than the X axis, though I am now pretty happy with both. I clamped my better micrometer stop on the bed, zeroed out the Y axis…

…and then racked it out far enough to insert a 7” Brown and Sharpe micrometer standard. I’m happy with the result.

Shorter standards got similar results.

All that’s left is cleanup and switching the X axis to read diameter. And check it with an actual turning.

Next up is seeing if the surplus tailstock I bought is closer to being straight than the one on the lathe.

Rick “traveled every week for the last seven—glad to get this done” Denney

 

[rwdenney]

Both my scales aim down. Any real risk in not installing the dust covers? The X axis is doable but the Z axis reader bracket gets in the way.

Rick “both fairly protected, it seems to me” Denney

 

[gard]

Rick,
Thanks for the write up, I have been considering the same thing on my 14 1/2 lathe for awhile. I have a little more limited space from the taper attachment to the wall in its current location, could you have mounted the cross slide scale closer to the center without affecting movement of the tailstock?

 

[rwdenney]

Rick,
Thanks for the write up, I have been considering the same thing on my 14 1/2 lathe for awhile. I have a little more limited space from the taper attachment to the wall in its current location, could you have mounted the cross slide scale closer to the center without affecting movement of the tailstock?

Not really, but maybe a little. Let me make a photo next time I'm in the shop.

I was constrained in locating the bar by what was reasonably flat on the taper-attachment connecting bar. It slopes up a bit to the flange where it attaches to the saddle, and I was avoiding that slope. But you'll notice the scale is even further out on that bar, and that was to avoid interference with the tailstock.

But also note that one does not usually need all ten inches of cross-slide travel on the 14-1/2" South Bend, unless you use a milling attachment. Nobody needs to place a tool behind the center of the spindle, because machining on the backside doesn't provide much value. With the spindle turning the normal direction, it will lift the saddle, and the saddle has very little to prevent it from lifting. And these lathes usually use screw-on chucks, so running the lathe in reverse isn't so desirable, either. Given that, you can give up a couple of inches of X-axis travel and position the reader a little closer in. The inboard end of the scale is the part in use with the took past center, and the scale will be using its outboard end when machining something large in the normal way. But you can move the reader inboard and then just use a shorter scale (maybe 200mm) to keep it from invading the space needed by the tailstock. That's a compromise, but maybe a workable one for most use cases, and it will reduce the stick-out in the rear by a couple of inches.

I thought about trying to mount it on the head-side of the carriage, but there was no way to avoid interference with the headstock when working close to the tip of the spindle using a collet instead of a chuck.

I also thought about mounting the scale above the bar instead of on the face of it, but then it interfered with the taper attachment clamp. One might be able to make a different clamp with more vertical clearance to address that issue. The scale would be reader-up in that position, however, and that's not a good idea for keeping chips out of the scale.

Making a new connecting bar for the taper attachment that incorporates the scale might help, too. See above in this thread. But to do that with any real accuracy would require a mill, and I'm currently afflicted with millessness.

Rick "making it work the red-neck way" Denney

 

[mattthemuppet2]

Both my scales aim down. Any real risk in not installing the dust covers? The X axis is doable but the Z axis reader bracket gets in the way.

Rick “both fairly protected, it seems to me” Denney

I suggest you do install some kind of cover. The risk of a chip getting up into the scale is small without them, but not zero and becomes more important if you're generating birds nests and stringy tangled chips that can go anywhere.