LCHIEN
In a previous thread, I asked for and got suggestions on obtaining 6" PVC pipe for my "Elephant" project.
http://www.bt3central.com/showthread.php?t=58035
Working with PVC pipe is a bit challenging and required some problem solving different than usual woodworking. At least partly because the pipe is mostly air and the reference points (e.g. the center) are not on a solid surface you can pin and or mark.
IN the referenced thread I resolved by obtaining some scrap pipe from my irrigation guy.
I concluded by asking how to make an initial square cut on this stuff (6" I.D., .290" Wall thickness. It had been crudely cut and a the 7' piece weighed quite a few pounds (30#?), a little ungainly to put through my bench tools.
Also had quite a number of other issues relating to cutting and marking this puppy.
Cutting a long piece off square
First problem: How do you draw a guideline around the circumference that is square with respect to the axis of the pipe and not tilted or zigzag?
after a few days comtemplation, I thought of my mom's old Dritz roll up yardstick she used for sewing. It was like a 1-1/2" wide piece of retractable measuring tape rule- curved cross section when laid out flat but if you pushed on it and flattened it out it rolled up neatly into a roll about 2" in diameter. It was fun to play with back then and would conform neatly to this pipe and allow drawing a straight line around it, as well as marking off accurately points on the circumference. Well, I found they haven't been made for years and on eBay were selling for around $20-25 as collector items. So I went to my shop and looked for plan B. I found a 6" hose clamp - stiff enough to keep a straight line on the surface of the pipe and large enough to go around. When tightened, it was perfect, I drew a pencil line around one edge but then decided to use it for the guide A 18-t hacksaw blade cut it after a rather laborious session but the edge was nice and square. I had marked off at least ten inches and this became my workpiece.
Cleaning up the other end
Now manageable, I had decided to clean up the jagged end using my bandsaw, I didn't want to hacksaw another end off. Unfortunately the pipe is 6.6" Dia and my 12" B.S. can only clear 6". I made a extended height length and height back for my miter gauge anyway. Wanting a finished size of 9" I had made the cutoff 10+ inches so I could make a couple of practice cuts. Being round I could cut an inch or so into the leading side of the pipe before it hit the top guide. So four or five cuts rotating between cuts would cut the circumference, it would be clean and match up if I used a length stop. Took a couple of tries practice making it 10", then 9-1/2 before making the final cut.
Chamfering the ends of the pipe
I put a 45" bit in the router table and put a small chamfer on all the edges, then cleaned the whole thing.
Marking the points of the clock
Now I faced new problems. I need to mark and drill holes on the sides at the 0, 90 180 and 270 degree locations. Meaning I had to draw parallel lines down the sides on four opposing sides separated by 90°. This was not easy. I had a center finder I calibrated but it was too short to span the pipe diameter. A HF adjustable square kit had a center finder attachment but when i used it it was way off. I had to calibrate it by filing off one of the rests for the ruler untill the two wings were at true 45 by a drafting triangle. After I spent time doing that I recalled I had a Starrett set I got off of eBay some time back- which turned out to be right on... But I did get the satisfaction of tuning that HF piece of crap.
Now armed with a good centerfinder, I was able to put 2 marks on the end edges 180 opposed. Spanned the pipe with a ruler aligned to these marks. Used a square against the ruler at its center and marked two more points at 90 to the original two points. Confirmed with the center finder that the two new points bisected the center.
Now I have four points at 90 degrees on the end.
Drawing the guidle lines
I want to draw a line from each end point down the side of the pipe to locate hole locations along the side. Using a T-square would be the usual way but the ends being round, the T-square did not set securely- the "T" head only contacted a very short piece of the edge. My solution: Clamp a tall block to the bottom of the T-head maybe 3-inches high and 7 inches wide. This gave me a t-head that laid flush against the ends of the pipe and I was able to mark a line perfectly down the side of the pipe.
Still has a ways to go before becoming a dog, or an elephant.
http://www.bt3central.com/showthread.php?t=58035
Working with PVC pipe is a bit challenging and required some problem solving different than usual woodworking. At least partly because the pipe is mostly air and the reference points (e.g. the center) are not on a solid surface you can pin and or mark.
IN the referenced thread I resolved by obtaining some scrap pipe from my irrigation guy.
I concluded by asking how to make an initial square cut on this stuff (6" I.D., .290" Wall thickness. It had been crudely cut and a the 7' piece weighed quite a few pounds (30#?), a little ungainly to put through my bench tools.
Also had quite a number of other issues relating to cutting and marking this puppy.
Cutting a long piece off square
First problem: How do you draw a guideline around the circumference that is square with respect to the axis of the pipe and not tilted or zigzag?
after a few days comtemplation, I thought of my mom's old Dritz roll up yardstick she used for sewing. It was like a 1-1/2" wide piece of retractable measuring tape rule- curved cross section when laid out flat but if you pushed on it and flattened it out it rolled up neatly into a roll about 2" in diameter. It was fun to play with back then and would conform neatly to this pipe and allow drawing a straight line around it, as well as marking off accurately points on the circumference. Well, I found they haven't been made for years and on eBay were selling for around $20-25 as collector items. So I went to my shop and looked for plan B. I found a 6" hose clamp - stiff enough to keep a straight line on the surface of the pipe and large enough to go around. When tightened, it was perfect, I drew a pencil line around one edge but then decided to use it for the guide A 18-t hacksaw blade cut it after a rather laborious session but the edge was nice and square. I had marked off at least ten inches and this became my workpiece.
Cleaning up the other end
Now manageable, I had decided to clean up the jagged end using my bandsaw, I didn't want to hacksaw another end off. Unfortunately the pipe is 6.6" Dia and my 12" B.S. can only clear 6". I made a extended height length and height back for my miter gauge anyway. Wanting a finished size of 9" I had made the cutoff 10+ inches so I could make a couple of practice cuts. Being round I could cut an inch or so into the leading side of the pipe before it hit the top guide. So four or five cuts rotating between cuts would cut the circumference, it would be clean and match up if I used a length stop. Took a couple of tries practice making it 10", then 9-1/2 before making the final cut.
Chamfering the ends of the pipe
I put a 45" bit in the router table and put a small chamfer on all the edges, then cleaned the whole thing.
Marking the points of the clock
Now I faced new problems. I need to mark and drill holes on the sides at the 0, 90 180 and 270 degree locations. Meaning I had to draw parallel lines down the sides on four opposing sides separated by 90°. This was not easy. I had a center finder I calibrated but it was too short to span the pipe diameter. A HF adjustable square kit had a center finder attachment but when i used it it was way off. I had to calibrate it by filing off one of the rests for the ruler untill the two wings were at true 45 by a drafting triangle. After I spent time doing that I recalled I had a Starrett set I got off of eBay some time back- which turned out to be right on... But I did get the satisfaction of tuning that HF piece of crap.
Now armed with a good centerfinder, I was able to put 2 marks on the end edges 180 opposed. Spanned the pipe with a ruler aligned to these marks. Used a square against the ruler at its center and marked two more points at 90 to the original two points. Confirmed with the center finder that the two new points bisected the center.
Now I have four points at 90 degrees on the end.
Drawing the guidle lines
I want to draw a line from each end point down the side of the pipe to locate hole locations along the side. Using a T-square would be the usual way but the ends being round, the T-square did not set securely- the "T" head only contacted a very short piece of the edge. My solution: Clamp a tall block to the bottom of the T-head maybe 3-inches high and 7 inches wide. This gave me a t-head that laid flush against the ends of the pipe and I was able to mark a line perfectly down the side of the pipe.
Still has a ways to go before becoming a dog, or an elephant.
Loring in Katy, TX USA
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