Alternatives for a DRO display change

[John HinkleyParticipant @johnhinkley26699]

After many months of soul-searching and cogitation, I have recently scratched my itch to acquire a mill.  Having down-sized my workshop a couple of years ago, I have purchased an Amadeal XJ12-300 Mini Mill with R8 spindle, gas strut-assisted head lift and fitted with a DRO.  It arrived last Wednesday, as did a new bench to keep it off the garage floor.  On Friday, with help from another forum member and a next-door neighbour it was lifted onto the bench.

Now, at last, to my question.  The DRO system as fitted “does exactly what it says on the tin”, in as much as it measures movement of the head and table in three axes and displays that motion on the screen. That’s all it does.  No ½ distance calculator, no PCD function or any of the other bells and whistles that higher end displays feature.  No moans from me about the system as supplied – I knew what I was ordering and got what I paid for and am happy to work with it for the time being.  I should add that the scales are magnetic and therefore of small dimensions and ideal for the size of mill, but the leads terminate with 4-pin aviation-style plugs, not the normal 9-pin D-plugs.

Soon, I want to replace the display with something more “fancy” and as I see it, I have a few alternative routes to follow:

1)  just replace the display with one like the Ditron D80 and rewire the existing plugs into 9-pin D-plugs, or

2)  buy a complete kit from cousin Ali and his Express team and discard the existing system (possibly utilise it on the lathe), or

3)  get myself a ready-built TouchDRO from Yuri and add an Android tablet?

If simply changing the plug terminations to 9-pin ones and attaching to a new display will work, I favour route 1.  I would rather avoid route 2, if possible on the grounds of cost and added complication.  Route 3 appeals for many reasons including its wide user base.  It’s not a cheap item and I’d have to purchase an Android tablet – but they are readily available on various auction sites.

Does anybody know, or have a good inkling, if the TTL 4-wire output from the fitted scales will connect to and work with either a new whizzed-up display, or the TouchDRO interface?

Or maybe you have a different idea on how you would spend my money?

John

 

[Stuart Smith 5Participant @stuartsmith5]

John

Can you post pictures of the display, scales and connectors?

I have made a couple of Touch dro setups, so may be able to advise.

Stuart

 

[John HinkleyParticipant @johnhinkley26699]

Stuart,

Thank you for your offer of assistance.  Below is a montage of the photos requested. The read heads themselves are approximately 30mm x 23mm x 13mm.  The only maker’s reference that I can find is on the back of the display – “CXM-3”.  Googling that only brings up a Czech web site which appears to market them with no technical info that I could find.  And a USA pdf showing how to connect all the leads to the display, as if that wasn’t obvious. Any other queries ask and I will try to answer them.

Regards,

John

 

[Stuart Smith 5Participant @stuartsmith5]

John

As you say, those connectors are unusual for dro scales. I suppose no matter what you do, you will have to do some testing to identify the ground and 5v pins. The other two pins will be the A and B signal pins. If I understand correctly, these will be a square wave signal offset by 90degrees.

This is a link to a page on the TouchDRO website explaining the connections:

https://www.touchdro.com/resources/scales/glass/glass-scale-pinout.html

You should be able to make adaptors for a Ditron or other readout with this information.

I made my two TouchDRO adapters a few years ago using an Arduino on veroboard. For the first one, I used cheap digital calipers. For the second one I had bought some scales with individual readouts from Arceurotrade but found the display too small, so made an adapter to use TouchDRO and a very cheap Android tablet.

Looking at the TouchDRO website now, you can buy a ready built unit or diy kit or build your own from scratch.

I suppose it depends how much you want to spend!

Stuart

[John HinkleyParticipant @johnhinkley26699]

Stuart,

Thanks.  What you say confirms what I suspected regarding the scales and ties in nicely with my own research but it’s nice to get some reassurance.  A little bit of experimentation is called for, methinks.  I’ll pluck up the courage to dismantle a scale lead plug and see what colour code is being used.  Tracing the 5V output from the display shouldn’t present a problem.

If I go the TouchDRO route, I’ll go for the built-up unit.  In about 2009, I tried building a veroboard based TouchDRO from the details given on the web site,  Couldn’t get it to work (with capacitive caliper-style scales from ARC) and gave that up as a bad job.  TouchDRO has come on leaps and bounds since than and looks a far more professional and polished product.  Only problem as I see it is if I mess up, a significant amount cash goes down the Swanee!  Well, you can’t take it with you, can you?

I’ll add to this post when/if I achieve anything.  In the meantime, I’ll check the accuracy of the installed system and get on with that.

Regards,

John

 

[SillyOldDufferModerator @sillyoldduffer]

Has the bought unit been given a fair trial?    Feels like it’s being rejected for not having features that may not matter in practice.  A DRO that calculates PCDs is a convenience, but not essential unless lots of PCDs are drilled.  For occasional PCDs jobs, any CAD package will calculate the coordinates, there are online calculators, and it can be done with paper and pencil.  Likewise, mid-points are easily calculated.  What essential does the DRO not provide?

Wanting to replace a unit with “something more fancy”, is understandable, but may not be wise.  Up to you – if money is no object, replace everything – accurate scales matched to a high-end DRO that comes with bells and whistles, needed or not!  Buy the best of all possible DROs and be happy.  The alternatives suggested aren’t the best possible. they’re all more work and risky.  Mix and match, and TouchDRO is DIY.

Nor for me thanks.  Having plenty of other things to waste money on, I’d stick with the paid for DRO until it let me down.  To me a DRO is just another tool, all they’re chosen by balancing utility and cost to meet a need.  Though bells and whistles are fun, I explicitly avoid them – they’re more to learn and go wrong at extra cost.

But it’s a hobby so do as you like, whatever a miserable git like me thinks!

🙂

Dave

[John HinkleyParticipant @johnhinkley26699]

Dave,

As one miserable old git to another, you won’t be surprised to hear that I agree with the sentiments expressed in your post!  I have not used the mill at all, let alone given it a fair trial.  I will give the as-supplied kit an extended experimental period before taking a deep dive into what could be a significant investment.  (Deep pockets – short arms.)

When I had one of these mills over 10 years ago, I was very new to the hobby and through ignorance coped well enough with plain digital displays.  No reason why I couldn’t do the same again.

John

 

[Nigel Graham 2Participant @nigelgraham2]

Having spent many years assembling and using electronic wiring, if the connector has only 4 pins it is because it needs only 4 pins: there are only 4 wires in the cable. Nothing wrong with “aircraft”-type rather than D-connectors, especially if genuinely to military or high-grade commercial quality. You’d need change them only to suit the replacement units. Why replace those anyway?

My milling-machine is a second-hand one too old to have been designed for DROs and the like, but I installed a 3-axis set by M-DRO, not something unknown from some Internet supermarket; and I am very happy with it.

The company knows our needs, and can supply what is right for the machine as well as user. I think I placed my order at the company’s stand at one of our exhibitions – certainly discussed it with the stand staff.

 

[Besides “our” suppliers deserve and need our support even if their goods are imported. Amazexpress and their ilk, don’t!]

 

It has many functions I have yet to use, including the halves. That can be overcome by setting the middle feature to (0, 0, 0) and read plus-so-far one way, minus-so-far the other, although that will lose any prior datum setting elsewhere on the work – often, a corner or a main axis. It also has PCD and arc calculator – oh, and calculator! – among various goodies I have yet to explore in the few years since I bought it.

Its only drawback is that switching between mm and inches (not within the same work!) seems to want the whole unit turning off and back on to register, which seems wrong – but that might be my fault. I may have missed something in the instruction-book! Which I have to say is very well written, in British English, not brave attempts without proof-reading.

.

Calculating pcd co-ordinates is not ever so hard though a bit laborious.

The Zeus books even include the appropriate factors. Or at least my editions do.

If you use ‘Excel’ or similar, create your own spreadsheet-calculator, using the diameter and hole-count as absolute-reference inputs. You could add further functions to give each hole’s co-ordinates from the primary datum on the work-piece.

CAD (2D or 3D) will let you plot a PCD anywhere on the item from its own centre, and obligingly gives that option of dimensioning everything from that primary datum.

 

As Dave says, be accustomed to what you have rather than what you think you want.

I think with careful planning you will find your apparently-basic DRO willl cover most of your milling, and the unusual rest by augmenting it with external help by calculator, spreadsheet, CAD or pencil-&-paper.

Let’s be honest – we are spoilt! A few decades ago we all had to count little marks on dials! (I still do, for small, simple operations.)

 

[John HinkleyParticipant @johnhinkley26699]

Nigel,

I concur with all that you say.  You are obviously not a viewer of my YouTube channel or you would know that I’m not new to DRO operations, having had a all-singing, all-dancing, DRO set-up fitted to my Warco VMC mill, bought in 2015. Consequently I’m used to and well versed in the extended functions available. Spoilt, if you like. Since selling all my machines a couple of years ago, the itch I mentioned in the first post got worse until the cream was no longer effective. Hence the situation in which I now find myself!

Perhaps, knowing what I do now, I should have purchased the more basic machine and fitted a “proper ” DRO system later. But I was too impatient. That’s my fault and I’ll have to live with that decision.

John

 

[John HinkleyParticipant @johnhinkley26699]

Just a quick update to this posting.  While perusing the Aliexpress web site a couple of days ago, I noticed a DRO display on offer for less than £40 , so I thought I’d take a punt.  This is the unit and the pinout diagram:

 

 

I’ll maybe order a couple of suitable connectors and make up a cable to link this display to one of my existing sensors and see what happens. I’ll post the results on here later. (When the smoke has cleared!)

 

John

 

[John HinkleyParticipant @johnhinkley26699]

Just noticed that that is the 2-axis version  Too late to edit the post.  I confirm that I’ve ordered a 3-axis display.

John

 

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