measuring into grooves

[engineer one]

amongst the many chores when making my coffee table is properly fitting the inner shelves.

so apart from making a set of bars, how do others measure the distance into the grooves.

since i am using mdf my tolerances are easier than if i was using real wood.

my method has been to dry assemble with clamps, and then measure the inner rail distance, then between the bottom of one groove to the other inner rail outside, and do the same the other way, then deduct the differences and add them to the inner rail distance. :?

apart from bar gauges then what are the alternatives??

paul :wink:

 

[Anonymous]

Rear of a vernier gauage measures depth with the thin peice of metal that lsides out

To measure across two slots, I clamp a couple of pices of 10mm*10mm wood together

 

[Alf]

Alternatives: the humble telescopic radio aerial or a couple of those plastic clip things for hanging posters sliding one inside the other. But frankly pinch rods aren't hard to make and can be held together with a couple of small clamps if necessary.

Cheers, Alf

 

[Anonymous]

amongst the many chores when making my coffee table is properly fitting the inner shelves.

so apart from making a set of bars, how do others measure the distance into the grooves.

since i am using mdf my tolerances are easier than if i was using real wood.

my method has been to dry assemble with clamps, and then measure the inner rail distance, then between the bottom of one groove to the other inner rail outside, and do the same the other way, then deduct the differences and add them to the inner rail distance. :?

apart from bar gauges then what are the alternatives??

paul :wink:

You start the job by drawing up a rod with all necessary dimensions marked full size, and after that you don't need to measure or calculate anything, you take dimensions straight from the rod. i.e. you lay on the work piece and mark off with a set square or similar.
This process verifies the design and eliminates mistakes. Also components can be made in any order and they will all fit. And it's much easier than all those little calculations - any one of which might be wrong, or lost on the back of an envelope etc!

Said it before - will have to say it again no doubt :roll:
cheers
Jacob

 

[Philly]

Paul
You can't beat actually measuring from the workpiece - Jacob's method can work but in the real world I find components have a way over being over/undersize. So measuring the gap makes sense.
Hope this helps
Philly

 

[andy king]

I agree with Jacob that a rod is always the way ahead, I use one for pretty well every job I do for the reasons Jacob makes, but if I have to drop in panels or such like, I do tend to take a measurement as well from the assembled pieces, as Philly suggests.
I do this either from a dry run or final glue up depending on the way the piece has to be fitted.
Sizes can alter fractionally by cramping or tweaking of joints for final fitting, so both work hand in hand for me.

Andy

 

[Anonymous]

Said it before - will have to say it again no doubt :roll:
cheers
Jacob

You may have said it again, and again, but you didn't actually answer the question that was asked :roll:

how do others measure the distance into the grooves.

A rod will not help measure groove depths, only help with marking out before construction and the slight variations in cuts etc. are not taken into account.

I rarely use a rod and am more than happy measuring and calculating which I find straight forward and pretty easy

 

[Anonymous]

Paul
You can't beat actually measuring from the workpiece - Jacob's method can work but in the real world I find components have a way over being over/undersize. So measuring the gap makes sense.
Hope this helps
Philly

Depends which real world you live in :shock:
A 12 pane sash window would have about 35 wood components. A 6 panel door and frame about 15. A typical job might be a set of 5 windows and one door; 190 components in total, each of which has to be cut to length, planed to size, morticed, tenoned, rebated, moulded, joined, wedged, fitted, housed etc etc. The hardware too must be fitted, housed, morticed etc.
How to keep track of all these components and operations and minimise error and waste, maintain accuracy, organise so that for example all the mortices are cut in one sequence?
The answer - a rod (or several rods). There's nothing mysterious or difficult about it - it just means that all the measurements & calculations which you'd have to do anyway, you do at the beginning just once and record in one place.
If you find that you are having to measure something in the middle of the job, from the workpiece, it means you have already made a mistake, ("over/undersize") and are probably making another one!
It works just as well and is just as essential for a simple job such as a single coffee table & shelf from 4 pieces of mdf

cheers
Jacob
PS if you find that components are "over/undersize" you either replace them (and work out how to cut them accurately), or, you modify the rod accordingly and alter the design. Much easier to alter a few pencil lines than to work blindly around some unwanted and unrecorded design variations!

 

[Anonymous]

snip
you didn't actually answer the question that was asked :roll:

how do others measure the distance into the grooves.

snip

Answer - you don't. You have already done it when you set out the rod. You will have drawn in a line for the depth of the housings.
You take the measurements from the rod to the workpiece directly so you don't need to measure it again.
Say you have 2 sides of a simple cupboard, of 18mm MDF at 600mm outside dimensions, with a housing for a shelf 10mm deep.
On the rod you make 2 marks 600mm apart, then 2 more marks 18mm in, then 2 more marks 10mm out from the 2nd marks. You then have it all set out including the length of the shelf in the housing without calculating it. You can take the measurement from it without measuring it. And you can see that it will all fit exactly as you have just drawn it up full size and there aren't any gaps.

cheers
Jacob

 

[Scrit]

Said it before - will have to say it again no doubt :roll:

:lol:

 

[Niki]

Hi Paul

I have 150mm, 300mm, 600mm and 1000mm steel rulers.

I push one into one side groove and another one to the other side groove and just add the numbers as on the pictures

Another method that I use sometimes is, measure the distance without the grooves, measure the grooves depth with the tail of the caliper and add.

Regards
niki

 

[Alf]

Jacob, thing is, if Paul hasn't used a rod and if his work isn't as precise as that anyway, then a rod still doesn't answer the question. Plus given the popular mantra of "measure twice, cut once", surely it's no bad thing to check the actual space as well as what it should be according to the rod? In addition to which if you don't have the luxury of doing this every day for money, but rather infrequently for love, then bitter experience shows it's best to check and the time taken in so doing is not a factor.

Cheers, Alf

 

[RogerS]

I hear what you say, Alf, but when I read Jacob's post I got one of those rare lightbulb moments and so, also as a casual user of the workshop, I can see how a rod could work for me.

Guess it's personal preference at the end of the day

 

[engineer one]

i have taken all the suggestions on board, and whilst i basically agree with
mr grimsdale, it does ignore certain things which happen when as alf says you are not doing these jobs often enough to have a proper knowledge base.

for instance if you use a plough plane then the wood may make your grooves slightly different because of spring back etc. and setting routers and keeping everything flat and smooth is also more difficult than it should be.

as usual niki has come up with a sensible solution, but i will make pinch bars, if only to use properly the veritas bar clamps that i have :lol:

of course then i have to change the blade in my table saw :lol: from mdf cutting back to real wood. but since i have to make some mouldings that is going to happen anyway.

paul :wink:

 

[Alf]

Oh I'm not against the rod principle - think that'll have to be done if I ever get these ruddy saw till doors off the to-do list - but it's not a solution to a situation half way through the job.

Cheers, Alf

 

[Alex]

Pinch rod, as described a few posts earlier. Two bits of wood 1/8"x3/4" one slips over the other to measure between the boards, while it's still in situ mark off the one rod on the other remove. Reassemble rods to mark and use to mark off shelf. Take two measures for front and back of shelf. You can also use pinch rod to check squareness if you put points on the end of the rods and measure across diagonals. :lol:
I mainly use pinch rods when doing staircase'sw with winders.

Alex

 

[Anonymous]

Jacob, thing is, if Paul hasn't used a rod and if his work isn't as precise as that anyway, then a rod still doesn't answer the question. Plus given the popular mantra of "measure twice, cut once", surely it's no bad thing to check the actual space as well as what it should be according to the rod? In addition to which if you don't have the luxury of doing this every day for money, but rather infrequently for love, then bitter experience shows it's best to check and the time taken in so doing is not a factor.

Cheers, Alf

Err, yes right I'm saying how Paul should have done it.
So how should he do it now? Wossa problem? Praps I've misunderstood the question but it seems to me that he should measure between the sides and add on 2x the depth of the groove/housing.

cheers
Jacob

 

[DomValente]

measure between the sides and add on 2x the depth of the groove/housing.

Finally !!

Dom

 

[Anonymous]

measure between the sides and add on 2x the depth of the groove/housing.

Finally !!

Dom

Was that it then well blow me down :lol:

cheers
Jacob

 

[engineer one]

worryingly that is what i done

just looking for better solutions in the future and i guess more accuracy :lol:

paul :wink: