The disadvantages of being an engineer

[JFDIY]

As the title suggests, I work in engineering and it's a bit of a curse sometimes.  I decided to run some 50mm solvent waste pipe as ducts to where our kitchen island will be, for passing services at a later date. These are in the thickness of the insulation under the screed. 

 

Anyone who's tried to cut channels in PIR will tell you how rubbish it ends up. I still wanted as best as I could, full support for the screed and no voids or big areas of expanding foam which I'd have needed if I stopped and started the boards either side of the pipe

 

Here's how it ended up.

 

Pretty pleased with that.

 

 

And here's how I did it

 

I rough cut the channels, then clamped a straight edge as a guide fence.

 

Then run the home made hole saw sledge down it using a long 1/4” extension and universal joint as a driveshaft as the drill wouldn't pass down the slot.

Note also the dust port for vacuum extraction which was essential to stop it all clogging up. Also found running the holesaw backwards made it grab less  which is a trick I'll use again when holsawing PIR

 

Time to build tool was probably 3hrs and the tidy up operation was 5mins per slot.

 

 

At this rate I'll be competing with @Onoff

in OCD stakes

 

[Onoff]

Sad git! ?

[ProDave]

That's neat that is. Well done.

[Onoff]

I must admit I just veed the pir, foamed it, cut flush and foil taped over. 

 

Respect.

[Russell griffiths]

That’s really nice. 

I would have just used the tip of my chainsaw ??

[Cpd]

A thing of true beauty! 

[Onoff]

Must bother you the writing's the opposite way on different boards! 

[Temp]

If you happen to have one of those soldering irons that heat up "instantly" you, can replace the  bit with a length of piano wire formed into a loop with shoulders. Run that down the PIR for nice neat u channels.

[SuperJohnG]

As a fellow Engineer...I do need to enquire how many days you procrastinated over this...any less than 4 and I'd be disappointed.

[dnb]

Nice job there. I was going with a home made hot wire cutter for mine when (if!) the time arrives for doing mine.

 

So, own up, who here isn't an engineer??

[ToughButterCup]

Oh if only the term engineer  meant something we could all understand! 

[SteamyTea]

7 hours ago, dnb said:

So, own up, who here isn't an engineer

Not me.

 

34 minutes ago, ToughButterCup said:

Oh if only the term engineer  meant something we could all understand

To true.

 

I worked at a place where all the fitters where called engineers. 

Same place that looked at me oddly when I said that there is a pressure drop over a long pipe run.  Then it became my fault when the installation did not work properly.

[JFDIY]

8 hours ago, SuperJohnG said:

As a fellow Engineer...I do need to enquire how many days you procrastinated over this...any less than 4 and I'd be disappointed.

 

Wish I only spent days mulling things like this over, it's usually weeks.....?

[SteamyTea]

Just now, JFDIY said:

Wish I only spent days mulling things like this over, it's usually weeks

I can ponder things for decades, and often revisit failed projects.

 

Two weeks ago I got my sewing machine out that I bought 12 years ago to do a project.  May get around to doing it now I have the most complicated of machinery working right.

I still want to know how these machines pick up the thread from the bobbin and loop it into the needle thread.  Magic I think.

[Russell griffiths]

42 minutes ago, SteamyTea said:

I can ponder things for decades, and often revisit failed projects.

 

Two weeks ago I got my sewing machine out that I bought 12 years ago to do a project.  May get around to doing it now I have the most complicated of machinery working right.

I still want to know how these machines pick up the thread from the bobbin and loop it into the needle thread.  Magic I think.

I must admit I look at the wife’s sewing machine, it is a magical piece of machinery. 

[joe90]

I have a sewing machine and it’s very satisfying to use (not used it in ages tho!). As an avid  DIYer building/constructing)inventing anything I find very satisfying. Regards planning I have been pondering on the landscaping fir months, fencing, chickens, lawn, garden, trees, drive. ???? @JFDIY that was a very neat solution.

Edited June 14, 2020 by joe90

[SteamyTea]

40 minutes ago, Russell griffiths said:

I must admit I look at the wife’s sewing machine, it is a magical piece of machinery. 

It is the quality of the components as well.  Makes a crank case or a wishbone on a car look like it was knocked up by a pikey on the side of the road.

Fishing reels are the same, they are a work of art.

[ProDave]

I knew the hot wire thing works for polystyrene (but oh the stink) I for some reason thought PIR had a much higher melting point and it would not work.

[Onoff]

1 hour ago, ProDave said:

I knew the hot wire thing works for polystyrene (but oh the stink) I for some reason thought PIR had a much higher melting point and it would not work.

 

It does work and cuts like the proverbial knife through butter. There's initial, physical resistance getting the wire into the edges of the foil facing. I was only cutting 25 and 50mm as a test. 

 

I experimented a while back making one with Kanthal / nichrome wire and a random wall wart for power. The wire kept snapping. Not sure because of over heating, physical stress or a bit of both. The psu failed eventually and I got bored as usual...

 

Started with a 12vdc 500mA psu and finished with a 830mA one (that died). 0.35mm dia Kanthal wire some 150mm long formed the cutting element to start with. There was some maths behind it. The radio control forum boys reckon a figure around 50W/m I think using 0.5mm dia wire for cutting polystyrene. As you apply power the heated wire goes limp immediately through expansion. I added a tensioning spring to my effort. 

 

 

 

 

From another forum it appears I ended up with this on the 12VDC 830mA psu:

 

"This time I tried 0.5mm dia Kanthal which has a resistance of 7.23 Ohms/m. So a 150mm element this time had a resistance of 1.08 Ohms"

 

Now consigned to the "must salvage the screws and bin" pile.

 

Guitar string some use I believe...

 

 

Edited June 14, 2020 by Onoff

[Ferdinand]

These ducts for 50mm pipes are between 25mm and 100mm in diameter.

 

(Said the person with the engineering degree.)

[SuperJohnG]

4 hours ago, SteamyTea said:

 

I still want to know how these machines pick up the thread from the bobbin and loop it into the needle thread.  Magic I think.

Haha @SteamyTea this has also always amazed me too. 

[dnb]

5 hours ago, ToughButterCup said:

Oh if only the term engineer  meant something we could all understand! 

If only... I keep getting cross with the IET professional registration people over this very issue.

[joe90]

https://www.google.co.uk/search?q=how+dies+a+sewing+machine+work&ie=UTF-8&oe=UTF-8&hl=en-gb&client=safari#kpvalbx=_1P7lXo3_H6-f1fAP8rCf4A462

[SteamyTea]

37 minutes ago, SuperJohnG said:

@SteamyTea this has also always amazed me too. 

And @joe90

 

It is really not looped at all, just twisted, but with some fabric between each twist, this creates the illusion of a loop.

 

My Mother told me that a woman has to have secrets.  That is good enough for me.

[joe90]

3 minutes ago, SteamyTea said:

It is really not looped at all, just twisted, but with some fabric between each twist, this creates the illusion of a loop.

I question that, if it was a twist it would surely  pull free!!!. The bobbin hook loops into the needle thread when the tensioner creates a space fir it. (How the hell did a building forum turn into a sewing forum ???). It must be a Sunday during lockdown, not enough to do.