Lathe DRO

[Stuart Smith 5Participant @stuartsmith5]

Jim

As Nigel and Brian say, the ‘whats this’ is the fixing for a clear plastic guard. I have just received the extra scale I bought from Warco to fit to my WM290. It has a max travel of 100mm and I intend to fix it in front of the compound using the the 2 threaded holes intended for the guard and the t slots. I haven’t exactly worked out how to do it yet but it looks like it will fit. I have just measured the compound travel on mine and it is 70mm.

Stuart

[duncan webster 1Participant @duncanwebster1]

The saddle handwheel on my Myford 254 has divisions at 0.25mm increments, and one rev gives 25mm travel. This is more than fine enough for most jobs. I can get to a thou using the DRO, as said before a saddle stop is a good investment (I've managed without for 50 years) Unless fitted with an aftermarket scale, ML7 and Super& didn't have a scale on the handwheel. If you really want fine control can you fit a handwheel on the end of the leadscrew? I must admit I have used a spanner on the nut on mine before now to get really fine.

[JasonBModerator @jasonb]

I would not use the tee slot in the cross slide to fix the read head, what happens when you want to angle the compound to turn a short taper or when you want to move the cross slide further in along the cross slide?

Better to fix to the lower half of the cross slide, either into the edge or more likely the underside.

Also don't forget being able to get to the compound lock screw if the 290 has one.

Edited By JasonB on 18/04/2021 15:08:03

[Jim Smith 8Participant @jimsmith8]

what happens when you want to angle the compound to turn a short taper or when you want to move the cross slide further in along the cross slide?

Good point which will will apply to any situation where you may want to fix a scale. Perhaps I stick to using the magnets for the scale and sensor mounts, then I can lift it off? Although on T bolts it can still be slid. I underestimated how big a 100mm scale actually is. The sensor head is around 60mm long enclosing the reader electronics, far too big when the electronics could be much smaller and they could have got them in a smaller box. As it is and they are all the same, overall length required to measure 100mm is nearly twice when you include the scale end mountings cheeks.

Thanks, I'll remove the guard fixing and have a look to see if my scale will fit the nearside. Is my lathe with the 'fine' handwheel control different to others because of the compound slide? My saddle traverse isn't just more coarse, but has more backlash compared to the compound traverse.

One thing I noticed was my toolholder can take up to 16mm sq. tools. However, with a 12mm tool In the holder I can only just get below the chuck centre line and a 16mm tool cutting tip would sit above centre (!). When the tool height is set at its lowest for a 12mm tool, it can't go any lower, unless some parts of the compound are altered.

Slightly off topic, but I guess you all know who used to make decent oil cans – Wesco etc. I bought a fancy new Castrol oil can off Fleabay suspected made in China. The most important part of a decent oil can is the oil doesn't run back leaving you to pump the trigger each time you use it. Oil in this Castrol oil can leaked back due to terrible manufacture and sealing of the 2 internal 8mm balls. I turned up a couple of ptfe inserts and used a 45 deg. drill to cut a seat for the balls. Oil can now works perfectly!

Edited By Jim Smith 8 on 18/04/2021 15:23:09

[JasonBModerator @jasonb]

You can get optical scales and heads that are a lot smaller than the limited range Warco do or better still go for a magnetic scale and micro read head.

Reilang can works for me

[Jim Smith 8Participant @jimsmith8]

Thanks. I've spent more time looking at it and the standard scale dimensions are just too large to make it work on my compound and keep the angular adjustment. Mounting anything on the side nearest the chuck is fraught with metal swarf entering the scale. On the front side I have a row of gib adjust set screws and clearing those, plus the width of the scale would need a huge stand off. In addition, I only have a 10mm edge of the the fixed platform to attach the scale reader to and the stand off gets ridiculously large to be stable. I can probably drill and tap that no more than M6 to attach a bracket, but not compact enough for the standard scale. The 100mm Chinese scale I have is the same form as the other two. Ali extruded box, 2 large end cheeks for mounting and a long travelling pickup for the optical grating. I did remove the end cheeks for a look inside and it's possible to replace those with brackets to reduce the overall scale length, but that doesn't help the depth.

I'll do some more research into more compact scales, preferably 5V TTL compatible with A & B quadrature outputs, not RS422.. Thanks again

[WearyParticipant @weary]

I have been playing about with fitting an optical scale in a similar restricted location and the smallest optical scale that I could find is the KA200 series (sometimes written KA-200), the scale of which is 16 x 16 mm with a reading head 14 x 14 mm (total height with clearances 32mm). It is available in the standard 5um and, from Germany, reading to 1um.

Should you find something smaller please post and let us know!

Next smallest optical scale I could find is the KA500 series with a scale dimension 18 mm wide x 20mm high with a reading head 14 mm wide x 20mm high; total height with clearances 43mm.

Regards,

Phil

[mechman48Participant @mechman48]

Posted by Journeyman on 13/04/2021 16:19:40:

Anyone who wants/needs to brush up on ** Lathe Nomenclature ** this may help

John

+1.. I've always used these 'X' & 'Y' descriptors since my apprenticeship, & also when I used to teach apprentices in training school, never used anything different.

George.

[JasonBModerator @jasonb]

A mini magnetic scale and head only need 14mm x 14mm

[WearyParticipant @weary]

Thanks for the link Jason. In the absence of a suitable optical scale I have already ordered a (small) magnetic scale, albeit not one of the tape versions that you linked too.

I was unsure about mounting the self-adhesive tape, and a previous enquiry on here (on a different thread) failed to turn-up any experience of use. I can always give the tape a try if I cannot fit the magnetic 'bar' in a way that suits me.

Thanks & regards,

Phil

[Jim Smith 8Participant @jimsmith8]

Thanks for the link. They cost a bit more than I wanted to take a chance with so I would like to hear from others who have fitted them on a compound slide? The magnetic tape seems to be the cheap and easy to get part compared to the reader head. Some of them are RS422 intended for long wires, but my Easson is 5V TTL. I'd also be interested to know if there are any reader sensitivity issues when the mag. strip is fixed against steel?

I looked up the Warco Chinese scale they sell for use on a compound slide. It's a slimmer version at 17-18 mm when standard is 20mm, but they come with some weasel words about making your own fixtures, which could be a daunting task when the present flush edge for the fixed table is only 10mm wide. If you buy a new Warco lathe with a compound DRO, I don't know how, or if they have fitted it, or just supplied it in a box for you to try and work out.

I'm very interested in a slim scale solution I could make work on my WM280V compound slide and all contributions are appreciated. Irrespective of whether the scale is optical or magnetic, I understand the reader head should have a firm mounting track. but I can't understand why the electronics sensor head is so large requiring a much longer overall length compared to the travel? One reason is to mount the durable output cable and something a lot smaller would be better for hobby lathes. The electronics in my cheap optical scale use DIL parts not miniature smd which requires a much larger box. I might see how much hacking about I can do, now I can see what's inside.

Edited By Jim Smith 8 on 19/04/2021 10:57:22

[KEITH BEAUMONTParticipant @keithbeaumont45476]

In reading this thread,although I will admit to being lost here and there, I would think that all the questions /problems of fitting a DRO to a WM 280V were set out in my article in MEW300, Fitting DRO to a Mini Lathe. It is just a question of scale. The system I installed has now been in use for two years and has not required any modification.

Keith

[JasonBModerator @jasonb]

MEW 300 was only two axis not one fitted to the compound, it also put the scale on the chuck side of the cross slide which is not ideal in a lot of peoples eyes and the 280 has a wider cross slide to make matters worse.

Jim, there is a thread on here where digital scales were fitted to a 280 and the guy doing it just bought tape and the small basic circuit board of the read heads and made his own housings. Small enough that he could fit the cross slide scale & head within the cross slide, can't remember if he did the compound or not.

Found the thread here

Edited By JasonB on 19/04/2021 13:10:19

[WearyParticipant @weary]

Jim Smith 8 – I have also sent you a Private Message.

Regards,

Phil

[KEITH BEAUMONTParticipant @keithbeaumont45476]

Jason,

I was not thinking about absolute detail,so much as the use of small reder heads and the application of magnetic tape.

Keith

[ChrisBParticipant @chrisb35596]

Posted by JasonB on 19/04/2021 13:07:50:

Jim, there is a thread on here where digital scales were fitted to a 280 and the guy doing it just bought tape and the small basic circuit board of the read heads and made his own housings. Small enough that he could fit the cross slide scale & head within the cross slide, can't remember if he did the compound or not.

Found the thread here

Edited By JasonB on 19/04/2021 13:10:19

Hi Jason, that's my DRO build thread. Didn't bother with the compound as I don't really use it that much, and to be honest I was even contemplating removing it altogether and replacing it with a solid tool post. True that the saddle traverse is a bit coarse, but using the DRO I manage to control my cuts without any major issues.

As for installing a dro to the compound on a WM280 internally, that would be very difficult, next to impossible I would say. First of all only magnetic types may fit and you have to have a very small read head. I built my own to very small dimensions and managed to fit one inside the crosslide, but the compound is even more restricted in space.

[RobinParticipant @robin]

My DRO shows X for saddle and Z for cross slide, but to change or set Z I have to press the Y buttons. I think they were as confused as me.

When I first had it I mixed up the X and Y plugs causing weird readings because the Z is a 5 micron scale while the X is a 1 micron scale. Nothing about that in the manual. I rang up and asked how to get into the settings and change it but they didn't seem to know or didn't want to tell me. The answer was to hold down the ENTER key while turning it on at the plug.

Where the cross slide DRO is fitted it removes 30mm travel from the tailstock which is fast running out of travel on the graduated part, whatever that calls itself. The nose? It cannot stay there, I am working on moving it.

[JasonBModerator @jasonb]

The reason for the 1micron scale on the cross slide is that as it measures radius your diameter could be double any error so 10micron if on the 5um scale was used.

I think magnetic strip and a mini head from M-DRO under the cross slide like ChrisB is the way to go.

As for how a scale could be mounted to the topslide, I would fit a piece of angle to the moving part, this could be fixed with a couple of M3 CSK screws and drilled to clear gib screws or you could make use of the locking nuts on the gib adjusters to hold it on. Stick tape to underside of angle. The head can be screwed to the side of the base or to a plate screwed to the underside. Whole thing sticks out no more than the gib screws and you are free to rotate and slide the topslide to where you want without having to alter mountings.

Quick mock up, head is actually a bit flatter.

Also room for the 10mm x 12mm head at end of leadscrew (its longer than my block) and a cover/extension at the back again like ChrisB and JS did

[ChrisBParticipant @chrisb35596]

Had a look at the compound slide this morning and I can confirm what Jason says, that's the best place to install the read head. As to do the installation internally in the compound, it is impossible with off the shelf read heads.

Posted by Robin on 19/04/2021 23:36:19:

Where the cross slide DRO is fitted it removes 30mm travel from the tailstock which is fast running out of travel on the graduated part, whatever that calls itself. The nose? It cannot stay there, I am working on moving it.

That's why it's better to have the DRO installed under the crosslide if possible, but that depends on what type of read out you have, my guess is it will only work out with magnetic type due to their small size.

[RobinParticipant @robin]

My toolpost is much too wide. See how the top slide is angled back, but the tailstock still only has 1 cm extension left to go. 'tis a puzzlement.

[Tony Pratt 1Participant @tonypratt1]

Same as my 290V, the cross slide is fairly wide any way & a DRO either side causes 'issues'. Just looked at a Emco Maximat lathe which the Warco lathes are I think clones of and the tail stock front has loads more over hang where the barrel is so you can get nearer the chuck with drills, centres etc.

Tony

Edited By Tony Pratt 1 on 20/04/2021 15:10:10

[ChrisBParticipant @chrisb35596]

This the closest the tailstock will ever come to the chuck on a WM280 lathe. Adding a dro to the right of the cross slide will only make it worse. You could mount the dro to the left, but that will expose the scales to oil, swarf and possibly impact damage.

Mounting under the cross slide as Jason suggested will avoid all those issues and tailstock reach will be unchanged.

[JasonBModerator @jasonb]

Posted by ChrisB on 20/04/2021 19:17:10:

This the closest the tailstock will ever come to the chuck on a WM280 lathe.

Unless it's an early model like mine where the carriage can move further to the right and touch the headstock

Not sure if a lack of stick out is classed as willy waving or not

Edited By JasonB on 20/04/2021 19:28:19

[ChrisBParticipant @chrisb35596]

How come Jason! Mine won't go any further as the saddle will contact the feed shaft clutch.

[JasonBModerator @jasonb]

Shear pin on mine. Also no Leadscrew spring cover or boxing sticking out the back where the motor goes.

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