x-dimensions and inset depths of fittings

[nick penfold]

Hey all,

I'm in my 2nd year of a college course doing both my nvq and tech cert.

Now, at work, i have no problems with any pipework etc. At college i find most of it quite easy. However, everytime it comes to building your typical frame in copper, plastics or LCS i seem to get the measurements out by about 2 or 3 mm.

Trust me, when i made the copper frame in the first year, i had to make it again about 6 times.

Im kinda wondering am i measuring wrong? i understand what the x dimension is and normally measure the inset depth by putting a piece of pipe in the fitting, marking off then removing and measuring the distance.

Kinda had the same issue with the plastic hep type stuff. im guessing that could be due to the inserts in to the pipe extending its length.


Is there a set technique to measure this x-dimension and inset depth?

is there any tech docs out there giving basic x-dim's for all the different makes of fitting?

did or does anyone else struggle with this at college?


i don't believe i should be having such trouble with this but for whatever reason i am.

Any enlightenment from the old hands or peeps still at college would be greatly recieved.

Nick

 

[migoplumber]

if you need to worry about 2-3mm for your college work, then you might be best asking your tutor for some more advice. sounds like your doing everything fine and in the real world 2-3mm is nowt to worry about. good luck

shaun

 

[johnmcginty]

All fittings are different , if you are referring to how much pipe goes in the fitting, or the z measurement which is taken from the exact middle to the beginning of the pipe it is usually the exact measurement of the pipe eg 15 mm z measurement is 15 mm on a pushfit! When you do this in the real world you wont use the same methods anyway so dont worry .

 

[dorset]

Hi
Whether or X and Z dimensions are used in the real world or not i am afraid they are in the 6129, here is an explanation i gave to another thread about the same topic
The x dimension is used for copper, push fit, soil and waste fittings and the z dimension is used for low carbon steel.
To find the x dimension measure the fitting from the centre to the end where you insert the pipe, then insert the pipe fully to the stop and mark on the pipe where the pipe meets the fitting. measure the amount of pipe that is inside the fitting and subtract that from the measurment of the centre to the end the figure you are left with is the x dimension.
Similar way to find the z dimension apart from the fact there is no pipe stop in LCS fitings, so you use the insertion depth. For example on 15mm LSC the insertion depth is 13mm so you take that off your fitting measurment and that leaves your z dimension.
Hard to explain this without the use of drawings but i hope this helps.

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[fuzzy]

what ever happened to centre to centre and end to centre, thats much easier than giving it a fancy name like X dimensions

 

[nick penfold]

cheers for the help peeps, i kinda understood the theory its just that i figured my measurements must have been off on the x dimensions. Got the frames completed no problems etc now. What i found interesting is that i have checked some of the other guys folders and had a look at the measurements they have put in for x dimensions etc and none are identical.

i thought it odd that if everyones x dimensions measurements were different by 3 or 4 mm in some cases then surely everybody would be cutting pipe to different lengths so surely their frames built at college would be of differing sizes (i.e. out by 3 or 4 mm).

And awwww crap LCS next

 

[Aqua Mechanica]

Don't worry, you're not alone, this is utterly infuriating. I made the frame to size, took a picture of myself with it and then measured it after taking the thing apart, lol

You're right, my measurements and everyone elses measurements were different, it's one of those strange anomylous things???

Once it's done, you'll never have to do it again, just think of it that way.

And the 2mm tolerance sucks. Nothing worse when you find one bit of the frame is 3mm out and the lecturer makes you take it apart.

A veteran lecturer would surely turn a blind eye if you could explain the principles of X and Z dimensions at that point and allow you to move on to the next task ;-)

 

[ste b]

hi, just joined the forum today and very pleased to have dropped on this forum,i was looking for the specific measurments which you subtract from the copper pipe length in the x dimension, i completed the z dimension with lcs tube,what a bloody nightmare i had searching for that,struggled a bit to work that one out then it all fell into place when the lecturer gave us a sheet with all the dimensions of the fittings which gave us exact size and what to subtract from the pipe length (3/4 and 1/2 inch),i am currently working on the x dimesion and was wondering if anyone knows where i can get hold of a referance sheet with all these fittings sizes........i dont have any fitting at home to measure,but i do have the fitting list.....cheers for any info and look forward to passing on any info which i can.

 

[Aqua Mechanica]

I think the insert depths can vary, no one ever has the same measurements in their folder and when I got my lecturer to check my measurements for Z Dimensions last week he was looking for an answer between two measurements 4mm apart. (This may well be to accomodate the 2mm tollerance allowed)

 

[ste b]

Cheers for the reply,appreciated,so the easiest thing to do is get the fittings and measure the distance required...........?

 

[vortexheating]

I use x and y dimensions all the time in my job it makes it easier and if its done correctly there is no reason why peoples measurements should be different. Attain the centre of your fitting by measuring from face to centre with your tape or a pair of calipers! then you can measure how much it goes in without having to mark anything take the inset of the pipe of the centre this will give you your x dimension.

 

[dontknowitall]

If you're using a standard tape measure, remember the metal part at the end that you hook on to or push up to (if you see what I mean!) will change the measurement by about 2mm.

Plumbing ain't precision engineering - but it does look great when you have true horizontals, verticals and 90 degree corners.

But as has been said before, out in the real world 2mm is nothing to worry about.

 

[fuzzy]

If you're using a standard tape measure, remember the metal part at the end that you hook on to or push up to (if you see what I mean!) will change the measurement by about 2mm.

Plumbing ain't precision engineering - but it does look great when you have true horizontals, verticals and 90 degree corners.

But as has been said before, out in the real world 2mm is nothing to worry about.

the metall end of a tape measure can be pushed in its depth ie, the 2mm to componsate. check your tape measure it should move at the end, many think this is a fault but it isnt.

when i worked on short peices, mainly steel i always used a steel rule, i found it easier and it fit into my level pocket quite nicely

 

[vortexheating]

Who made it up that 2mm in the real world doesn't matter. Because if you make that error three times that means that your whole piece will be 6mm out. Never say that will do its all go to be thats right.