Reading carriage travel - range is 0 - 13 mm
A digital read out unit that will improve your machining accuracy for less than £10
I can’t claim to have come up with this neat idea and credit where credit is due. I came across this tutorial via MadModder forum at users.tpg.com.au/agnet/micro.html and it really is worth passing on to you.
The idea is based on a digital tyre tread depth indicator currently available for just £4.99 on eBay. With a few simple modifications the unit will attach to your lathe as and when required to measure cross slide travel and carriage travel to an accuracy of 0.01mm. The unit can also be switched to imperial mode. It also has potential to measure travel on your milling machine.
You will also require some 10mm x 2mm earth magnets and I bought 10 for less than £4.00, again on eBay.
So how does it work ? I hear you ask. Well, lets suppose you are turning down an aluminium round, perhaps to make a 10mm diameter piston where precision is essential. You have turned it down to around 11mm and getting close to the finished size. Right so here is what you do.
1 Using a normal digital caliper you have determined that you have turned down to say 11.10mm.
2 Deduct the finished size of 10mm from the 11.10mm and you will see that you need to reduce the diameter by a further 1.10.
3 This equates to 0.55mm radius.
4 Position your Micro DRO so that the probe is just starting to be depressed and zero the readout.
5 Wind in your cross slide until the reading is 0.55mm and take your final cut.
It really is that simple.
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- Digital Tread Depth Gauge cheap as chips on eBay for £5 and that includes p & p.
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- Remove sticky label, and you can remove sticky gum residue with brake/clutch cleaner.
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- Remove cell battery CR2032, larger than usual digital caliper battery.
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- With label removed you can now undo the four screws on back of unit.
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- Remove and discard the flat metal tension spring from the side of the slide.
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- I superglued a 1/8th brass pipe nipple to retain the compression spring.
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- I uncoiled the spring at the base of the probe to prevent it entering the unit body.
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- A square steel plate was araldited to the body as the magnet mount.
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- 4 x 10mm earth magnets secured with Araldite on steel plate.
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- Monitoring movement of the cross slide for precision turning.
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- Reading carriage travel – range is 0 – 13 mm
Have you considered fabricating a metal shaft to replace that plastic one? I just received 2 of these from ebay and feel that the plastic shaft maybe prone to breakage. Thanks for the info!
No that hadn’t occurred to me as with the Mklll versions there is virtually no pressure on the probe shaft so I don’t consider it to be a problem, though time will tell !
John