Gallery, Projects and General > How do I??

Anyone Ever Shortened a Shahe DRO Scale?

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awemawson:
I'm fitting a DRO to my Thicknesser  which is part of the Dominion Woodworker - it doesn't need to be anything too precise - nearest 32nd of an inch is fine !

I've bought (Alliexpress) a Shahe 12" scale - I only need 9" of travel and although not essential to shorten it, it would make mounting a tad easier. It's going to be magnetically attached, and to preset the reading the plan is to thickness a bit of wood, then slide the mounting magnets until the reading corresponds with the previously thicknessed wood.

It looks as though the scale part is made by the yard and could just be sliced off where needed, but is this the case  :scratch:

. . . anyone actually know for sure ?

John Rudd:
They are standard scales with an aluminium substrate....just cut to length and all will be well in the world...

Done it several times and no one died...

awemawson:
Thanks John, that's reassuring to hear  :thumbup:


 :mmr:

PekkaNF:



Not sure about that one, but pretty sure it's capacitive scale, most of them are incremental (no position information is coded on them, no home-position or anything) and there is a metal base, which has a narow groove to house PCB, that has an etched pattern (picture above). Top of that is protective tape.

Nothing is harmed when it is cut cleanly. Pretty much only danger is related to PCB/tape entagling to saw blade, I would leave some extra and cut carefully trough the top layer.

There are some exotic models, like both scale and reader are powered (you see cable connected into scale too) and/or absolute postion encoding....like these:
http://www.kappasense.com/kappasense-technology/

Many uncommon flavors, but the cheap ones are all basically the same construction than cheap verniers (picture on the top).

Pekka

awemawson:
I've not actually cut the scale yet, however I bent up a crude bracket to join the 'traveller' sensing head to the Thicknesser thickness indicator using a rare earth magnet - just proof of concept.

Seems to work remarkably well - the readings in the photograph of the DRO and the digital vernier are genuine - 1 thou apart ! but the eagle eyed will notice that the digital vernier is on 'hold' as I couldn't keep it in contact AND take a photo

Quite pleasing. I think that I will now 3D print an adaptor that will bolt to the sensing head, and present the 15 mm rare earth magnet pressed into a hole and angled at the required 45 degrees to match the pointer on the Thicknesser

(The reason for shortening the scale is to allow more room to slide it on it's magnetic mountings to allow me to preset the DRO)

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