Hi all,

Just thought i would give everyone using the M503 digital readouts a heads up on a potential issue. This may simply be a case of "you get what you pay for" & i'm ok with that sometimes.?

I originally used one of these DRO's on the crosscut fence of my old machine. Well i took that one off my old machine when i sold it, and have been using it on my new machine for the past year or so. It's been dead on accurate the whole time, so much so, i decided to see if i could make something work for the rip side of my CF741. That too worked, however i was never happy with the way the mag tape just hung in no-man's land at the gap between the saw/shaper table, and the jointer outfeed table. I figured that would some day become an issue, but trying to find time to fix the issue wasn't easy. Finally i put some thought to it, and added some aluminum angle to the saw side as support, and put on a new mag tape to get the join slightly further towards the jointer side, since the old tape didn't line up exactly.

This is where cracks started to appear in the system. I can only assume this is an issue with the magnetic tape, since that is the only thing i have changed, but now i don't seem to be getting an accurate reading. I can "zero" the fence to my known position, but then either side of that point, it seems to creep out roughly 1mm either side. One thing i have added this time around was the thin metal adhesive backed strip that is supplied with the magnetic tape. I assume this is simply to protect the magnetic tape? Could this be the casue of this innacuracy? I guess that is where i should start, by removing it, and seeing if the accuracy improves. If not, then it will be the tape itself & i will try replacing that.

I will let you know how i get on, but wanted to give others a heads up, since this has basically rendered mine useless until i sort it out.

Regards,

Bryce

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https://www.brycecomerwoodworks.com/
https://www.youtube.com/channel/UCHdrRaAZd_pOa7wwbdNPUEw

Hi Bryce,

Hi Imran,

No the zero'd position seems to be exactly the same every time. It's either side of that point that it drifts out. I have tried using a Starret measure stix on the magnetic tape before and found the reader didn't read at all, so wondered if the metal tape was the issue.

Regards,

Bryce

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https://www.brycecomerwoodworks.com/
https://www.youtube.com/channel/UCHdrRaAZd_pOa7wwbdNPUEw

I guess I am trying to ask if the issue occurs at any place along the path or in one location? You can zero it anywhere and check if it provides incorrect displacement.

Double check that the read head is not loose and distance and angle with respect to the tape is within spec. If you have another piece of tape you can check the read head against it however if it is only off by 1 mm that could be hard.

I have 4 DROs (3 M503) and all have the SS tape on top of mag tape with no issues.

Thanks for the reply Imran,

I checked the distance between the read head and the tape and it doesn't vary. What i did however just try, was zeroing the read head at 600mm and 800mm and then again at my known point of 86.1mm. Then when i put it back to 800mm it was reading correctly. I then put the fence to 700, then back to 100mm stopping to check every 100mm, and every time it was spot on regardless of which direction i was travelling. I really can't explain what happened. It's like it calibrated the readhead on the tape or something. Is that even possible? I thought the mag tape was based on alternating magnetic fields that were spaced 5mm or whatever apart. Again, i cannot explain it, but it looks as though the descrepancies i was getting are resolved.....Ok, after i wrote that, i realized i hadn't taken the fence off, put it back on and zeroed it again at my known point, so i just went and did that, and sure enough, it is reading dead on again! It looks like it's spot on thanks Imran, I don't know how you did it, but you did it!!! ?

I will have to keep an eye on this over the next few days or even weeks, and keep checking it. I will report back in a while and let you know what if anything i have found. Hopefully it is now resolved, and the issue doesn't occur again.

Regards,

Bryce

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https://www.brycecomerwoodworks.com/
https://www.youtube.com/channel/UCHdrRaAZd_pOa7wwbdNPUEw

Hi Brian,

Yes the magnetic tape is definitely tricky to set up after having cut it. You are right about putting it down then cutting it being problematic. That was the problem i ran into the first time i put the tape on for the rip side. Unfortunately there is no other option other than cutting it though so the jointer table can tilt up. What i found after some trial and error, was that i could carefully reduce the length of one end of the tape little by little until it read exactly as though it were one continuous piece. I guess to the exact distance of the next pole? Anyway, i seem to have it reading correctly now after messing about with it. Even after taking the fence off and putting it back on, (then zeroing it) it is reading spot on. I can't explain it, but for now at least, it seems to be working as it did before i replaced the mag tape.

Thanks for your help on this one.

Regards,

Bryce

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https://www.brycecomerwoodworks.com/
https://www.youtube.com/channel/UCHdrRaAZd_pOa7wwbdNPUEw

I did not do anything, I am glad it is working again. I am impressed that you were able to join two sections of the tape, I would not have likely even given it a go.

Imran Malik

Thanks Imran,

Yes the join in the tape was necessary due to how the table lifts up. I thought i could simply cut it but the two pieces together and it would work, but it turned out that it wasn't accurate. I used the edge sander to first carefully clean up one end, then reduce the length of the other part until it read accurately as it passed over the join. It worked the first time i did it, and i'm glad to say it worked the second time as well, so i'm confident enough to say it can be done. :)

Reards,

Bryce

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https://www.brycecomerwoodworks.com/
https://www.youtube.com/channel/UCHdrRaAZd_pOa7wwbdNPUEw

When researching cost-effective DROs, I found the M503 and LP-02 models confusing—they appear to be nearly identical in size and design. I ended up purchasing a few LP-02 units, and based on the documentation, it seems that using multiple segments of tape is a valid use case for the LP-02 (or at least, that’s how I interpreted the manual—it’s not exactly Pulitzer-winning English, but I think that’s what it meant).

?

On Tue, Apr 1, 2025 at 10:57 AM, Rohit Kulshreshtha wrote:

LP-02

Thanks Rohit,

Indeed it looks like you can have multiple sections of tape. I'm not sure i want to be going through that procedure though each time i move from the first part of the tape to the second, so i'm glad it's working how i have it set up currently.

Regards,

Bryce

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https://www.brycecomerwoodworks.com/
https://www.youtube.com/channel/UCHdrRaAZd_pOa7wwbdNPUEw