cutting the bar of a digital calliper

I am making a vertical motion scale for the quill on my mill and for the sake of cheapness I am adapting a 100mm digital calliper. The bar that slides through the measuring head is slightly too long and needs to be shortened. The bar carries the printed circuit scale that is read by the read head and this will need to be cut.

I know that the bars can be cut without damaging the reading system on the linear scales that are used on DRO readouts, but what I am not so sure about is whether you can do the same thing with the scales on callipers. Has anybody cut one of these scale bars from a calliper and does it matter which end is cut?

On a related matter I dismantled the 100mm calliper I bought for this task and was horrified by the state of the inside surfaces that are normally invisible. The inside was filthy with machining muck and pretty crudely machined, while the visible parts were very nicely finished with the jaws mating perfectly. It definitely pays to clean up the inside of these cheap Chinese callipers. After reassembly it felt much smoother in action.

Doug

You can cut the bar with an abrasive disc. I think I remember reading that with a bit of care the actual PCB which is the reading surface can be removed and stuck back on again. If you do shorten it without the surface near the cut may not work if it gets too hot.

This guy **LINK**

has done something very similar. I've cut the bars on capacitative scales with a dremel/diamond disc without problems.

Robin

I did a similar thing with a Warco Digital read out which was to long for my quill feed. I just cut it with a hacksaw and replaced the end cap. The measuring scale underneath the plastic coating was just a zig zag copper track which was not affected by cutting

Norman Blackburn

for the fine bladed hacksaw. I have shortened several scales with one.

regards

Thanks for the replies, I can cut the hardened bar with a 1mm thick cutting disk, I was just not sure if the pcb track had some vital element at one end which should not be cut, and if so, what end to avoid cutting.

Doug

I just bought a proper vertical scale from Warco, about £14 as I remember and easy to read.

I was going to get a proper vertical scale but the cheapest one I could find was going to cost nearly £30. I didn't look at Warco though so perhaps I should have looked further. You are right Vic about easy to read, I will have to suffer having to read the scale sideways, and probably end up thinking I should not have been such a cheapskate and bought a proper vertical scale. Too late now!

Doug

Thanks for that link Robin, it looks as if you can butcher the scales without a problem. I was concerned that there might be some important end copper track on the pcb under the bar of the scale, but it looks as if it is just a continuous zig zag pattern. The pcb is probably churned out in long lengths then cut to size.

Doug

Cheapest I can see on eBay is £18 but it has a remote readout on a long lead. Anyone tried these type?

Yes, I've used a couple of this type to provide a DRO readout on my lathe. A miser's way of doing it but from my point of view definitely worth doing, uses a couple of coin cell type batteries which have not needed replacements in two years. To be fair the type that I bought have an auto shut off if no movement detected after a few minutes but it's not hard to get into the habit of manually turning them off.

Phil

Have a look here; I have used these on my mill without any probs so far. Change the batteries once a year, they can be use in the horizontal or vertical to suit your needs...

https://www.arceurotrade.co.uk/Catalogue/Measurement/Digital-Readouts-with-Dedicated-Remote-Display/Digital-Readout-Bars-with-Dedicated-Remote-Display

George.

I got mine from ARC,it didn't need cutting, the down side I used to forget to turn it off and it quickly flattened the battery, so I made a 3 volt DC power supply, which is separately fuse but fed via the inverter input, low voltage led light the same. Now when switch off the machine every thing is off. One has to be careful with the soldering iron when making connections in the original battery box, be very quick. John

I have used "cheap" digital vernier calipers for DRO on my lathe and mill. Please be aware that on most of them when you switch them off it only turns the screen off, the unit keeps running and of course flattens your battery. All of these calipers that I have seen are----- 1.5V------- DC. I have also built a power supply for my DRO with a 12v output for LED lighting, 1.5V for caliper/scales and 5.0v to power the DRO brain (arduino pro mini).

Wow that's almost as much as I'd pay for a lathe!

I cut WARCO supplied DRO scales with an abrasive disk in an angle grinder on a stand after finding that my best hacksaw blades would not look at them. I have been using IKEA 2032 lithium cells for the xy readout and they go flat in no time. 4 sets of two in 12 months

Rik