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Laser distance measurers


Vijay

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Hi,

 

I understand that laser measurers work by sending a beam of laser light to the object and measuring the time it takes to get back. What I've wondered after using mine is how accurate they are on the red laser dot or is the red laser dot just a rough guide to aim at and not very accurate?

 

Vijay

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There's a difference between the ones that really use a modulated laser to measure distance and the cheaper (usually for indoor use only) ones that use an ultrasonic measurement beam with a laser as a guide.

 

If it's a genuine modulated laser one, then the distance is the line from the front of the unit (or the offset reference mark) and the actual red dot.  If it's an ultrasonic one, then the red dot is the approximate aiming point, and the distance measured will be the closest ultrasonic reflection near that dot.

 

Most of the decent outdoor ones are pretty good now.  The same can't be said for the ultrasonic ones.  The early ones were pretty good, the later (and much cheaper) ones can be a bit less accurate.  Worth checking the description carefully and looking at the front of the unit to make sure it really is a laser measure.  There are a few sellers on a certain auction site that are selling ultrasonic ones as if they were laser ones, just because they have a guide laser.

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The one I have is a Bosch DLE40 unit and I believe is a proper laser unit. I've had an ultrasonic one and I think a tell tale sign of them was the meshed double sender/receiver units on the front.

 

Any idea what colour is best to make targets? I thought red but it didn't work too well over a distance of 18 odd metres, but could have been the size of the target too which was about 150mm square

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5 minutes ago, Vijay said:

The one I have is a Bosch DLE40 unit and I believe is a proper laser unit. I've had an ultrasonic one and I think a tell tale sign of them was the meshed double sender/receiver units on the front.

 

Any idea what colour is best to make targets? I thought red but it didn't work too well over a distance of 18 odd metres, but could have been the size of the target too which was about 150mm square

 

White retro reflectors seem to work OK.  I bought a bag of mixed red and white ones, about 50mm in diameter, to fit to our fence posts and found by accident that a red laser shows well on the white ones.  You could also consider using a bit of the white reflective tape, the stuff like this: https://www.ebay.co.uk/itm/White-High-Intensity-Reflective-Tape-25mm-50mm-100mm-1m-2m-2-5m-3m-4m-5m/141961676553?var=441087551075&hash=item210d934709:m:mAexwak8OiBVkg26oiCIO5Q

 

I've not tried it, but it may well work pretty well.

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5 hours ago, Vijay said:

Hi,

 

I understand that laser measurers work by sending a beam of laser light to the object and measuring the time it takes to get back. What I've wondered after using mine is how accurate they are on the red laser dot or is the red laser dot just a rough guide to aim at and not very accurate?

 

Vijay

Mine are all Hilton 

The Green beam I bought for £1600 plus vat 10 years ago

The green beam is much easer to see and the receiver will pick it up at a 100 mtrs

Two clicks and it will scan and draw the beam in

If you have setting out work that needs to be very accurate it’s worth hiring a kit for the day

Hilti Topcon

Spectra 

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21 minutes ago, recoveringacademic said:

Works a treat on the reflective tape in a hi viz  jacket.  So, if you see a hi viz jacket with reflective tape that's missing .....:ph34r:

 

Is it honeycomb reflective on hi-vis?

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13 hours ago, Vijay said:

Bosch DLE40

 

We have one as well, and it definitely reads long.

 

I have 0.3m, 0.6m, 1m and 1.8m steel rules which are all consistent with my steel tapes to around 0.1mm / metre (using the standard mobile phone camera trick to take the measurements).  

 

If I use the Boch to gun an internal door frame height and then compare this to the two overlapped steel rule method, the Bocsh consistently comes out 1.5 -2 mm longer over ~2.1m.  I trust the steel rule measurement to 0.2mm, so there's no way that my DLE40 achieves the claimed 0.5mm accuracy.

 

So IMO, the Boch is brilliant for measurements up to maybe 15m accurate to 5mm, say  (though you do need to do the longer range measurements after dusk because of S/N ratios.)  However, it isn't good enough to measure up for  cutting oa piece of wood and to get it right in one cut.

 

PS, isn't it about bloody time that you arranged to come and see us or @RandAbuild one W/E when you are next in Roade.  We've got to build up the local self-build mafia! xD 

Edited by TerryE
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8 hours ago, Vijay said:

just stripped the reflective strip off a hi viz so will give that a try :)

Or just fold the non reflective material over!

According to my CSCS test I recently took,that hi vis will now need to be thrown as it is soiled or defective. 

May as well strip all the reflective gear off it then & hope yellow waistcoats become a fashion trend :))

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6 hours ago, TerryE said:

PS, isn't it about bloody time that you arranged to come and see us or @RandAbuild one W/E when you are next in Roade.  We've got to build up the local self-build mafia! xD 

 

lol I know. Not been up as much as I'd have liked cos of the rubbish weather, it was just slosh up there last week :( I'm looking for a caravan at the moment so once the better weather arrives, I'll be staying there a few nights a week to cut down on the driving and longer working days - I'll be a regular visitor then lol

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Vijay-consider s trailer tent when the time comes. 

Ours is 4 berth & I can put it up in 40 mins or so on my Tod. 

When folded down,much harder for the local youngsters to make ‘improvements’ on the nights you’re not there. 

Also,far cheaper,I’d say. I see 2nd hand models advertised under £1000,check out Gumtree & the others. 

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58 minutes ago, Brickie said:

Vijay-consider s trailer tent when the time comes. 

Ours is 4 berth & I can put it up in 40 mins or so on my Tod. 

When folded down,much harder for the local youngsters to make ‘improvements’ on the nights you’re not there. 

Also,far cheaper,I’d say. I see 2nd hand models advertised under £1000,check out Gumtree & the others. 

I'm just looking for a very cheap caravan, just the shell would do so I can throw in a double bed. It really is only to crash in so don't need any other real creature comforts ;)

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1 minute ago, Vijay said:

It really is only to crash in so don't need any other real creature comforts ;)

 

Until you start to use it, then you'll want washing facilities, wc, brewing space etc etc :D

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  • 2 weeks later...

Noticed today that when using my laser measurer aiming at reflective tape, it throws out the measurement, it adds 6-10mm. It also doesn't get a quick quick on the distance.

 

Anything else I could try?

Edited by Vijay
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