Making Sight Glasses pt1
In another fantastic tutorial our local copper guru P3t3rpan shows us how to make sightglasses from scratch out of copper. All of the pictures are his and I have left his words pretty much the same and added a small amount of content.
Like em or hate em they are fun to make..................
First you are best to make a template. This can be achieved with some arcane tech drawing skills or by using some free software from the web. I have a paid app on my iPhone that is easy to use and very accurate. This is what it makes;
- InglisHill adds, the template as you will see is a shape that is wrapped around the pipe so that it has the right curve to fit to the circumfrence of the column you are using. Here is a link to an online version that can be used http://www.metalgeek.com/static/cope.pcgi printing can be interesting because it needs to be set to the correct scale. The most important part is to make sure that the straight line at the back of the template is straight and that it matches up correctly.
Decide upon the clearance you want for your fastening system. Shorter is better. This is 20mm but could have been a little less.
Wrap your template around your pipe/tube/mount
Make sure you understand where to measure and use the same place for each , I use the throat of the piece. That is , the shortest length to the face of the glass mount.
Now crack out the Wiss snips making sure you have had a good breakfast.
- InglisHill adds, I have been known to scribe the line with a scriber and use an angle grinder to cut and then shape this part of it. Considering I work with Stainless rather than copper it makes sense, Stainless is a bit hard to cut with snips :) I use a 1mm cutoff disk to rough it out then a flapper disk (sandpaper disk) to do the final contour.
Always make 2 cuts, 1st cut.
1st trial fit.
Now you can use your custom copper vice protection pvc to hold some sandpaper onto the parent tube.
Back cutting the inside edge will speed this part up by making it thinner.
Nearly there. More time and patience here pays off in a nicer join.
Almost, so that was 14minutes without stressing. 32 minutes from marking out.
A good chance to use up all those annoying off cuts of coarse sandpaper.
Here you may see the thinning/angling of the edge. Here is where you see the value of undercutting with a file first.
Oh I forgot. Plan on having a small angle to encourage draining of the sight glass. This can be achieved while you are lapping the sg extension by applying more pressure to one side or by exploiting a dodgy cut you didn't intend to make.
Next time we will look at making the "easy flange".
So this concludes the first part of the Tutorial, stay tuned for the rest :)
The original messageboard post can be found here http://www.nzhomedistiller.org.nz/forum/viewtopic.php?f=15&t=570