DRO

[NJHParticipant @njh]

[NJHParticipant @njh]

 

Hi All

 

My query is with David Clark’s comments on DRO in MEW 152. (David this is not directed specifically at you – but of course your comments would be welcome!) Firstly I fully agree with you the near necessity of fitting one to the mill. However I have just upgraded my trusty lathe to a Super 7 and I am seriously considering adding DRO to that. Although I have been “model engineering” for 30 yrs my only “professional” experience was in a brief retirement job where I had access to Colchester Bantam with DRO. I found it wonderful – ability to work in metric or imperial, any backlash in feedscrews now immaterial, the ability to set the required diameter and then carve away until “0” reached. On the “Z” axis just touch the tool on the end of the job, set the length to be turned then feed down to the shoulder and repeat until the required diameter achieved. I accept that a stop would be good for multiple items but surely for “one offs” the DRO is quicker? So before I submit my case to higher authority any thoughts and experiences you may have would be valuable

 

[David Clark 13Participant @davidclark13]

Hi there

Just with many years working in industry, I never really found the need for accurate working with a read out on the lathe.

I would prefer not to rely on a readout for turning.

Usually I was working so accurately that a readout was unreliable.

 

To work to tenths of a thou, I prefered to cut, measure and move to finished size.

Trying to finish to a tenth with a read out was a waste of time.

regards David

 

 

[NJHParticipant @njh]

 

Crumbs David !

 I’m impressed – I have neither the skill nor the equipment (or maybe the need?) to work to a greater accuracy than 1 thou. Your post though does raise some interesting questions in my mind. All my digital measuring equipment gives me a precise number and presents it in a way that gives it authority – but how accurate is it? (Just because it says “2.34765” do I believe it?) Is its accuracy consistent throughout its range, is it affected by temperature / changes in temperature, humidity, power variations, age ?. If it is so affected by how much? A DRO system is a fairly hefty investment – what life can I expect from it – are any faults repairable and when it does fail will the whole system need to be replaced? How easy are systems to fit and what processes do I need to follow to ensure the alignment and security of the sensors? 

How about an article in MEW ?

 

Cheers N

[CirclipParticipant @circlip]

And whoever writes the article, be sure to include a FOOLPROOF way of keeping turnings and crud off the nice expensive heads and slides 

 

   Lifespan?? Not alot if you manage to “Tap” them with a spanner or chuck key.

 

   Can you put an article in MEW teaching people how to read “Handraulic” measuring tools, dials and how to compensate for backlash David???

 

    Regards  Ian.

[David Clark 13Participant @davidclark13]

Hi There

I have just (last week) fitted a readout to my Tom Senior mill.

I can now pitch holes out to tight limits till the cows come home.

 

Crud

I just fitted the relevant covers. I found it very easy to fit the slides and the head.

All you need is a bit of care.

 

Cutting fluids

It seems to work fine but I doubt I will use more than a brushful of oil.

 

Dials can easily by read to less than a thou.

You can easily guess to 1/2 a thou and probably a lot more accurate.

 

Not sure what you mean by Handraulic?

 

Readouts and digital equipment are reasonably accurate but they usually read

to the nearest 1/2 thou. Micrometers can read to tenths of a thou if you get the micrometer with the correct scale. If you need to work to anything less than a tenth of a thou then a digital mike is essential. (And yes, I have had to do this sometimes.) Would not want the agro now though.

 

I am a firm believer that if we did not give designers computers, we would not have to work to such tight limits as they could not design to such tight tolerances.

regards David

 

[HasBeanParticipant @hasbean]

As it happens I’m now looking at fitting a 2 axis system to my mill. I have an Ortec Z axis display at the moment but that company seems to have disappeared! I seem to remember having seen them advertising fairly (?) recently.

Anyone know if they are still in existance?

 

Paul

[mgjParticipant @mgj]

No, but I have just bought one from DRO Systems who advertise in ME for the mill, and that is just fantastic, and a genuine 24 hour delivery.

 

1 Mistake – I bought a 2 axis one because I had already put a digital scale on the z axis. I wish now for convenience, I had put all 3 in one box. 

 

I am going to put one on my lathe. Not because of the accuracy and turning to shoulders, but to turn a modern metric machine into a  proper imperial machine at the touch of a button. I accept I may have to do a bit of conversion for the last smidgen if being super precise, but its a lot better than having to convert completely. And for most purposes the DRO will be fine without converting to metric. And of course, I can feed figures in, in Imperial, and have them metricated at the touch of a button and work in metric from then on. Lot of conveneience for me.

 

These scales read in tenths, and the resolution is 5 microns which is about .2 of a thou – or a bit less. 

[CirclipParticipant @circlip]

Handraulic ref was to the NON battery operated system of measuring David, seems we’re loosing the ability to do anything that needs a thought process.

 

  Computer use for design would be fine and would have probably sorted the recent frame “Hiccup”, only trouble is, getting the guy who’s driving the puck to understand what he’s designing and to be able to control the dimensioning system to logical sizes rather than the programme forcing it.

 

  Lot to be said for a sharp pencil ( OR a blunt one for that matter)

 

   Regards  Ian.

[HasBeanParticipant @hasbean]

Meyrick, was that from Allendale (Machine DRO) by any chance?

They are one of the suppliers I’ve been looking at.

 

Paul

[MichaelRParticipant @michaelr]

I am still working with Calipers, Dividers and rule, and making one part to fit another

[mgjParticipant @mgj]

Yes – if you already have scales and a box,  if you look at the tech specs, it will give you the voltages and pin functions/numbers on the connectors. You might (hopefully) find that you could use some of your existing stuff. you could possibly rewire a D connector. Give them a bell- they were very helpful.

 

Those who have used these things will know, but the grief I went though milling the steam face for the traction engine. 2 Faces at 2 levels. Three steam slots of different widths (cutter dia) so while the are all the same length the cutting distance each side of zero is different. Then the inlet and exhaust slots are of different depths – and you have to mill all that and the steam pocket and not loose zero. It was a seriously concentratious exercise – not difficult, but one really wanted to keep ones marbles in hand.

 

Now I just set up 10 SDMI points and enter the co-ordinates from datum – 4 pocket corners, and the 5 ends of the slots – having adjusted all the slot lengths for the cutter diameters, and it counts down for you. When you get to  X0Y0 you have reached the end of hte cut. Its repeatable so if you have to cut a steam slot in several passes, you’ll never lose datum or distance. Sorry to rave on about it, but this thing is just the dogs…..

 

No more having to take my socks off when I run out of fingers so I can use toes as well – it has a decent calculator all built in.  Just marvellous.

 

Now now Circlip – you still have to know how to do it. this thing just stops you from forgetting where you’ve go to while you were remebering.

Edited By meyrick griffith-jones on 14/08/2009 19:18:33

[mgjParticipant @mgj]

Sorry – 6 ends of slots.

 

Proof of mental decay and need for DRO.

[DugsonParticipant @dugson]

I can’t help buying into this regarding DRO’s on hobby lathes 

 

I ran a precision grinding business for 15 years where we regularly worked to tenths or microns. Although DRO’s are fitted to cylindrical grinders, in my experience they are not much good for achieving final size as this is determined by the number of “spring passes” or wash out passes carried out; and this is determined by the condition of the grinding wheel when finishing; you dare not rely on the DRO with  these variables, so stop and measure is essential.

 

Finish grinding is usually the last process so the cost of going undersize is sometimes very high both in dollars and reputation.

 

All this is in support of David’s comments about using the DRO for sizing because the same arguments apply to turning unless you own a very rigid modern lathe and even then you still must measure if size is important.

 

As far as metric/imperial goes a calculator does a fine job for me I would rather have an uncluttered lathe, a DRO on a Myford is pretty tight for room.

[Jim NolanParticipant @jimnolan76764]

 

 

I have both a Colchester Bantam and Bridgeport fitted with DRO’s. Nice big digits on the screen no more glasses on, off, where did I put them malarkey. I have them both set up so they click over at ½ thou intervals. Do I measure when the read out says 0 yes more likely I measure when its plus 10 and I know the next cut will be spot on. 

I would not say they area measuring instrument, they are an indicator. I still use mics etc., to check the size although more often than not I needn’t have bothered. Plus all this did I turn the handle back or not terror is a thing of the past. Its also very reassuring to see the DRO register movement when you move the dials on those last few size cuts where you never knew if the table had moved or not. 

As too mounting them and clutter the Newall ones I have can come with different length pivoting arms so mine are mounted on the wall.  

Reading your post all the advantages are in it, just catch HWMBO on a god day and slip one in under the radar.

 

Jim

Edited By Jim Nolan on 15/08/2009 07:41:39

[mgjParticipant @mgj]

I suspect we need to differentiate between milling and turning.

 

Turning I can quite agree that a mic is still necessary – and you have to remove spring from either job or tool, especially when boring.So a DRO would simply be a convenience.

Millling  – well its a lot more difficult to measure to a turning degree of accuracy – think of a slot with its radiused ends. How long is it – exactly? Also when turning, you really only have one axis in operation at any one time, and when you don’t its easy to make or set up a stop. Milling, mostly one is cutting on 2 axes, and sometimes on three.

 

Next point is  (and mine is the budget one – there is a more swept up version), a DRO will calculate co-ordinates for laying out a line of holes, and at an angle. It will do PCDs as well. So its a set of sine bars  and half a dividing head – all these sorts of things. And the metric conversions.

 

Again, I can quite understand that one would want to use a mic to check, in the same way that one uses one to check the result from the feedscrews. And yes, of course one can do without – I did for 25 years – but it don’t half improve life when you do have one.

 

Oh indeed – .

 

(Its a bit like the difference between using a slide rule and log tables compared with the modern scientific calculator. How many would go back to a slide rule for their long multiplication and trig? Me – well I could do Fourier and Laplace transforms if I had to (signal processing and aerodynamic control systems being my MSc), but I’d rather let a pre-programed chip do it…….better still, one that someone else has programmed!)

 

 

 

 

Edited By meyrick griffith-jones on 15/08/2009 09:18:28

[Kenneth Jones 1Participant @kennethjones1]

I have just fitted a DRO to my GH universal Mill. I have fitted the X scale at the back of the bed, unfortunatly this covers up the oiler hole for the slideway.

My plan is to reposition the oiler to the top of the bed by redrilling the bed in the new position.

In MEW 168 there is an article which describes the fitting of oilers to a Taiwanese lathe cross slide but no indication of a supplier. Endless trawling of the web has not given me any help in location of these items, can anyone direct me to a supplier?

I need  an oiler to fit an 8mm hole.

[NJHParticipant @njh]

Hi Kenneth

 

Arceurotrade do them try here :- http://www.arceurotrade.co.uk/Catalogue/Machine-Spares/Lubrication-Accessories

 

Hope that helps

 

regards

 

Norman

[BogstandardParticipant @bogstandard]

IMHO, the main advantage of a basic DRO is so that backlash on your machines can be totally ignored. In fact, I don’t even look at dials any more. Plus the speed at which repeatable sizes can be achieved. The rest of the features come in handy every so often, PCD drilling, drilling along an angled lines etc.

 

Having 4 axis on the lathe and 3 + 1 on the mill allows me not only to machine to exact size, but do it time after time. I used to make up to 100 fine tolerance parts, all to within 0.0002″, At those sorts of tolerances, even ambient temperature has to be taken into account, so they were all produced, hopefully within a couple of hours, just so that fluctuating workshop temps didn’t cause too much of a problem. Having to do that sort of thing manually would have taken me most of the day

 

They have allowed me to take basic workshop machines, and produce items that would normally have to be made with hi spec toolroom equipment, or the very slow process of cutting down to size manually.

 

I am not saying they should replace being able to manually machine, because I do that a lot as well, but as an aid to machining. It wsn’t too long ago that mills were a major luxury in a small machine shop, now they are being classed as a neccesity. The same will be for DRO’s on machines.

But I can honestly say that since starting to use the basic scale systems about 6 or 7 years ago, and now the Sino units from here DRO’s , have given me everything I need to assist me in accurate machining and faster than I could ever do without the use of jigs and fixtures,.

 

This is not a tool gloat, but a natural progression for myself, to produce the items I need, to the tolerances I require, much faster than I could ever have done manually.

 

 

Bogs

 

 

[Kenneth Jones 1Participant @kennethjones1]

Thanks NJH, thats exactly what I needed to know, and only a quid each!

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