Magnetic strip DRO

[John MCParticipant @johnmc39344]

I have the option to buy one of these from a friend who now has no need for it.  Its an “LP20E biaxial magnetic grid displacement meter”, according to the instructions.

I would like to use it to replace a “vernier calliper” (aka digital scale?) type DRO that eats batteries, this one comes with a mains power supply.

Anyone had any experience of these?   I’m interested in accuracy, repeatability, reliability etc.  Mounting looks straightforward enough.

So, over to you guys, what do you think about them?

 

[bernard towersParticipant @bernardtowers37738]

You would need to know the accuracy of the mag tape

[Nigel Graham 2Participant @nigelgraham2]

The gap between the tape and sensor may be fairly critical, too. Fitting an M-DRO set to my mill, I used a plastic feeler-gauge to set it. It was actually a strip cut from an expired association membership “card”, by chance the correct thickness for that particular DRO set.

The strip and sensor obviously need protection from coolant, oil and swarf too.

[bernard towersParticipant @bernardtowers37738]

Yes when buying new (from MDRO) I got a plastic shim in the kit

[Bo’sunParticipant @bosun58570]

Good morning John MC.  I’d suggest talking to someone at Allendale (M DRO).  They may be able to supply compatible magnetic scales.  They will also have the necessary mounting hardware and scale covers.   I’ve found them to be very helpful.  Admittedly I was buying a complete DRO kit from them.

[Speedy Builder5Participant @speedybuilder5]

Re battery problem, why not use an external power supply, several options Both on ME and internet – why fix something that is not broken?

Bob

[bernard towersParticipant @bernardtowers37738]

Yes definitely dump the batts, Iused a wall wart with 4 usb outlets and used dummy CR2032s with wires attached to connect to the usbs. It works well

[JasonBModerator @jasonb]

John MC Said:

this one comes with a mains power supply.

 

And to me that is the magnetic strip/scale curled up in the photo so no need for a compatible one.

[howardbParticipant @howardb]

|”Re battery problem, why not use an external power supply, several options Both on ME and internet – why fix something that is not broken?”

Why bother? Why fix something that needs batteries that cost a quid apiece? Why not get on with something productive?

[JasonBModerator @jasonb]

Are people reading the opening post or my post pointing out that John MC said “this one comes with a mains power supply”

[John MCParticipant @johnmc39344]

Many thanks for the replies.

Nigel, good tip about using a plastic “feeler” to set up.

As for using dummy batteries connected to an external power supply.  We, my model engineering friends and I, have had variable success with these.  Either working perfectly or problematic.  The problems include not working at all or unstable displays that spoil accuracy and repeatability.  It may be something to do with an insufficiently stable voltage supply, so I have been told?

I was hoping there may have been someone with real life experience of this device who could give a measured opinion on it.

As for productivity, perhaps one should avoid forums altogether and get on with making something.

 

 

[John MCParticipant @johnmc39344]

To conclude this thread I went ahead and fitted the DRO, mains powered, so no need for endless battery replacements as was the case with the previous set-up.

Accuracy is good, as is repeatability.  Thanks for the tip re plastic feelers, made setting up easy!

The magnetic strip and head are hidden behind a cover so, hopefully, well guarded from swarf.

The photo shows the setup.  I firmly believe that aluminium has no place on machine tools, except for, perhaps, belt covers and the like.  I made the exception here and used a couple of bits of al/alloy to carry the head.  The magnetic strip is supported on a 3mm thick strip of steel.  This, in turn, is supported by two 2BA studs.  This allows the strip to be moved around to get the necessary adjustments correct.

[Nigel Graham 2Participant @nigelgraham2]

There are plenty of places for aluminium alloy on machine-tools, but supporting DRO components is a particularly good one. The brackets supplied with the M-DRO kits are die-castings.

[Author]

Posts