Accurate measurement of internal dimensions - telescopic measuring rod?

[David]

I have a gap into which I want to insert a cut piece of wood. [More detail available if necessary.]

The gap is around 345 mm but there is a slight recess so I can't eyeball a tape with the exact measurement (although I haven't found that very accurate when I'm doing it anyway).

I thought of a sliding measure which could be locked when it fitted the internal dimensions.

I looked on line but they all seem to be 1 metre plus minimum length.

Does anyone know of such a measure or have a sneaky alternative method?

I was hoping to set a rigid measure, then transfer the measurement directly to a piece of wood which I would then cut to fit exactly.

Cheers

Dave R

[Chris Hogg]

Use a telescopic aerial for a portable radio, something like this

[polygonum_on_google]

Something like a bigger version of

?

[David]

Stumbled across this.

I've ordered one with a (hopefully) matching folding rule.

It seems to do the job.

There was an associated video which showed it doing more or less what I want to do.

Cheers

Dave R

[Tim Lamb]

In message [e-mail]>, David [e-mail] writes

Two pointed bits of wood, longer than half your 345 (say 250 each). Insert into hole gripping the overlap. Rotate to 90 deg. and adjust until you are confident you have found the largest diameter. Remove from hole and mark the overlap before relaxing your grip:-) Transfer the length to your tape measure...

[Steve Walker]

for 345mm, I'd suggest two overlapping 12" steel rules.

[Brian Gaff (Sofa]

Yes but for short lengths I simply bought some plastic knitting needles and cut one a bit too long then filed it down so it was an interference fit and you can allso see if the gap is tapered or pissed as the technical bloke might say. They used to be pennies in markets. I'm going back a bit in time though. Trouble is with telescopic things with no lock you can easily muck up the length. Brian

[nothanks]

+1, or just two pieces of wood. It would be daft to buy a special widget when it's so quick and easy to make something suitable.

[Murmansk]

You can tape measures on a reel that have two sets of numbers, the ones on one side are for measuring internal gaps like yours, you read the measurement through a window on the top.

[Andy Burns]

I have a Hultafors Talmeter, another designed to take internal measurements

[David]

Thanks. That is a really clever design.

Cheers

Dave R

[The Natural Philosopher]

Every tape I have bought in the last 20- years is like that

[Dave Plowman (News]

I had a tape measure ideal for this. Called a MarkOMatic.

You could measure an alcove then directly mark a shelf to fit it, using the pencil lead or scriber in the device body. There were also leads and scribers at the front of the body for say copying a shelf directly - and in neither case did you need to remember the true measurment.

It was such a useful device I was surprised to find it NLA when the tape in mine finally broke.

There are slightly similar on the market, but non as good.

[Andrew]

Or two lengths of bamboo cane (for runner-bean support) strapped together with some elastic bands.