Lathe DRO retrofit - single axis vs dual?

[Just a Sparky]

Debating different options for improving my ability to quantify carriage movement on my 13" South Bend. Presently I just use a 2" travel dial indicator clamped to the ways which registers on precision flats on the carriage. This works fine right up until I have a part with precise longitudinal dimensions greater than 2".

Option 'A' is to go to Ebay and buy a 6" travel indicator. Simple and relatively cheap (compared to a DRO.)

Option 'B' is to slap a DRO onto the 'Z' axis. [carriage]

My dilemma in regards to the latter is whether or not it is worth it to try to add an 'X' axis scale [cross-slide] while I'm at it. On a South Bend toolroom lathe which does see use of a follow rest from time to time, that's easier said than done. Most of the conversions out there rely on the follow rest mounting holes to attach the scale. Not only is that a problem for my scope of use in and of itself, I also don't like the way it interferes with the tailstock base. I would be more inclined to remove the factory taper attachment tang and replace it with one of my own making with mounting provisions included in it's design. A big friggin' deal that would greatly injure the aesthetics of the machine just to gain one more axis.



I've used plenty of milling machines with DROs on them in the past, but never a lathe. I guess what I'm trying to ask here is; How much would I be missing out on with a single-axis DRO as opposed to a dual-axis? From my personal experience, it seems like the 'Z' axis on a lathe is the only one that would really benefit from the absolute positioning a DRO can provide. It is often necessary to locate features lengthwise along a part being turned. The 'X' on the other hand is almost always fed incrementally rather than absolutely, by way of two or three measurements taken on the fly which get calculated into feed values.

How substantial is the benefit of an 'X' axis scale on a lathe in your guys' experience? What are your thoughts on DRO vs indicator?

 

[MrWhoopee]

I bought the cheapest most economical 2 axis DRO I could find for my Heavy 10.

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I only intended to install the z axis, being perfectly happy with the dial on the cross-slide. I ultimately broke down and installed the x, once I figured out how to mount it.

This was almost 5 years ago, it's been perfect.

 

[wood2steel]

Sparky,
the z axis scale is a simple install on the 13 Southbend as I have my 16" outfitted as well. Still prefer to run my dials on all crossfeed operations. You'll wish you had installed sooner once you've run the Dro a month or two. Both Lodge and Shipleys as well as the Leblonds are out fitted with z scales. Only the 84" Leblond runs a Trav-a-dial. PM if you need any pics of the mounting setup brackets

 

[Terry Keeley]

Just did this on my Emco awhile back and was debating to go two or three, SO glad I put one on the compound as well!

Lathe DRO install.

I liked these tiny magnetic scales I put on my mill so much I installed them on my lathe. Electronica Mechatronic Systems: Magnetic Linear Encoders - Magna Slim I got them direct but I think they're also available from DRO Pros.

www.practicalmachinist.com

 

[michiganbuck]

Another option is a set of JoBlocks, set to be a stop or set to feel with your indicator.

 

[neanderthal mach]

Magnetic tape scales and compatible reader heads have been available for awhile. And I'd agree there's many lathes that have definite issues installing a more standard glass or magnetic dro scale to the cross slide without interference with gib screw adjustments for non tapered gibs, carriage locks or those bolt holes for steady's. These https://www.machine-dro.co.uk/dro-i...pare-parts/magnetic-tape-and-support-profiles can be mounted in a thin machined slot on the bottom side of the cross or top slide and between the way surfaces. That web site is in the UK, but I'd think there available from others. Figuring out there compatibility and signal out put with whatever your current display uses would be up to you.

This video shows the details about the machined slot requirements starting at the 1:50 mark.

And that Myford he's mounting it to is a whole lot smaller than your 13" SB. But there other methods and options out there than mounting those larger scales to the side of the cross slide.

 

[neanderthal mach]

ooops, double post

 

[wood2steel]

I believe you will find in many cases on cross slide; the bulky glass scales mounted on shorter 30" & 42" between center lathes, you will occasionally run into clearance issues with tailstock use near that scale; as a result i finally removed that scale on my 14 x 30 L & S. Lighter duty machines are definitely more forgiving given their narrower cross slides

 

[bikemutt]

I've not tried this so, theoretically, if you have DROs on the cross-slide and the carriage, it should allow for faster and more precise setup of the taper jig. For a MT#2 at 0.005"/inch, set zero on both scales, run the carriage in by say, 6", then adjust the taper jig in (or out) by 0.3", lock it in.

 

[M.B. Naegle]

IMO, it's worth it to have a DRO on the cross-slide, and it wouldn't be hard to temporally remove if it got in the way of work or a follow rest (think of it more like an accessory than a part of the machine). It's handy having both axis able to easily zero, convert to metric, and most DRO's allow toggling between diameter or radius read-out on the 'X' axis. I've used Acu-rite for all our shop machines and they also give you a tool table so you can set separate zero offsets for each tool. I still use my compound dial for depth of cut, though that's more of a muscle memory thing I think.

To protect the scale, I like to drill and tap a screw into the base of the tail stock so that the screw head hits the saddle before the tailstock contacts the scale.

 

[eKretz]

I just made an MT #5 to Jarno 18 adapter for a customer at the shop where I do some part time supervision and training (make an occasional part now and then) the other day. The readouts were a great help in getting the taper attachment set quickly. I just ran an indicator from the carriage to the taper attachment guide bar and used the readouts to move exactly 6", checking the fall of the indicator across that distance. From there two indicators at the ends of the guide bar and a quick tweak and it was all set. Very convenient.

I have recently installed a DRO on my lathe at home, wouldn't be without one if I had any choice in the matter. I've got X and Z axes, wouldn't be without both either. Tool offsets that follow Tool 1 are very nice for multiple parts. I don't have much of a desire to throw a scale on the compound. I made a cover for the scale that screws down to the top of the cross slide - any force from the tailstock bumping the cover should be directed against the cross slide and keep the scale safe.

 

[Mr.Smith]

IMO, it's worth it to have a DRO on the cross-slide, and it wouldn't be hard to temporally remove if it got in the way of work or a follow rest (think of it more like an accessory than a part of the machine). It's handy having both axis able to easily zero, convert to metric, and most DRO's allow toggling between diameter or radius read-out on the 'X' axis. I've used Acu-rite for all our shop machines and they also give you a tool table so you can set separate zero offsets for each tool. I still use my compound dial for depth of cut, though that's more of a muscle memory thing I think.

To protect the scale, I like to drill and tap a screw into the base of the tail stock so that the screw head hits the saddle before the tailstock contacts the scale.

Yes! This, 100 times this.

Thank you,
Mr.Smith

 

[Just a Sparky]

I like the idea of that compact, discreet magnetic tape scale on the cross-slide. Just not sure how to make it play nice with the taper attachment. The read head will have to be centered with the binding stud for said attachment unless I offset the scale and read head as a pair. Maybe a rigid 3/8" plate plasma cut to fit the follow rest holes and extend towards the back of the machine? Bolt heads from mounting said plate would sit proud enough to protect that thin tape. Would only loose 5/8" of carriage travel that way. Could recess it into a milled slot to help protect it from swarf if desired. Could put the read head on the back right of the saddle. Or make a clamp to grip the static half of the taper attachment. I'm all for not drilling into a pretty antique if I don't have to.

If the read head and scale are not permanently attached to one another then it would be an extremely simple matter to pull the scale off when needed...

 

[wood2steel]

You youngsters are spoiling yourselves with all these flashy electronics;
But I'm here to tell you; if the lathe doesn't have a Z axis Scale in place; it's going out the door on Crlist for FREE!

 

[neanderthal mach]

Well since I've never owned a 13" SB or used one of those magnetic tape type scales I can only take guesses. What your actual dimensions are would say for sure, but it might be possible to do some light machining on that supplied guard the reader head uses and a bit more on the bottom side of your slotted link to the taper turning attachment, and still get it all mounted a bit different than that video shows with bolts through the reader head cover and into the bottom of that link. But blindly buying something like that tape scale and reader head won't work, first and as I mentioned, you need to know what signal type your current dro display works with and the plug type the dro display has. If it can all be made to play nice with each other, that mounting location does solve a number of issues the side mount and bulkier scales all have.

In general I wouldn't go with a removing and reinstalling that scale unless you could ensure it goes back into the correct 3 dimensional alignment every time without have to double check it with an indicator. That would just be an all round pita to do a full realignment each time.

 

[bikemutt]

If the read head and scale are not permanently attached to one another then it would be an extremely simple matter to pull the scale off when needed...

The scales I'm working with (optical), have plastic ends on them which may be removed, oddly enough with 3 screws in an intuitively 4-hole configuration, I'm sure there's more to it than meets the eye though. Nevertheless, the head and the scale on mine do come apart if needed.

 

[guythatbrews]

Z axis for sure.

X is nice but what I don't like about it is approaching a number is not as natural as it is with a dial. Not sure why this is. I don't have trouble on a mill but the lathe cross slide dial just seems to be easier than the dro. I often use dial for quick roughing infeed and dro to hit finish size.

The tape deal sounds interesting but all things considered you may just want to stay with z only.

 

[eKretz]

Z axis for sure.

X is nice but what I don't like about it is approaching a number is not as natural as it is with a dial. Not sure why this is. I don't have trouble on a mill but the lathe cross slide dial just seems to be easier than the dro. I often use dial for quick roughing infeed and dro to hit finish size.

The tape deal sounds interesting but all things considered you may just want to stay with z only.

I find that completely the opposite of my experience. I use the X axis like a CNC does. I punch in the actual diameter and do the math while roughing in my head. One semi-finish cut for tool pressure correction, then finish cut.

 

[Just a Sparky]

Thinking out loud here...

I could probably piggyback off of the two bolts holding the taper attachment in place to mount a bracket for a read head.

And I'm thinking I could sandwich some material between the cross-slide body and the taper attachment tang to serve as the foundation for a long, straddle-type bracket to encompass the outer perimeter of the tang, with a dog-point bolt at it's end bearing on the tip of the tang to mitigate issues arising from vibration. Think glorified Cobra clamp. Presto, mounting point for my scale.

Just like that - zero holes drilled in cast iron. Except for the 'Z' scale, but y'know... that's fairly discreet.

Edit for the visually inclined:



In retrospect, mounting the kit on the left side of the tang might be better so it won't interfere with the follow rest... but that's why we draw napkin sketches like this.

 

[guythatbrews]

I find that completely the opposite of my experience. I use the X axis like a CNC does. I punch in the actual diameter and do the math while roughing in my head. One semi-finish cut for tool pressure correction, then finish cut.

Yeah I set actual diameter too. And I set the cross feed dial to actual diameter, so for .250/rev dial 3/4" diameter is 0.

I guess I communicated poorly. It seems much easier for me to quickly hit a number on the dial than on the dro. It's boom on the dial but slow on the dro. Probably just me.