Shaping Small Parts From PVC





Introduction: Shaping Small Parts From PVC

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first ...

With a Pyrex measuring cup, a little water, a piece of PVC, and a microwave you can shape plastic pieces that enable you to do and make useful things.

WARNING: Our PYREX cups are several decades old and work well with high heat.  I just learned PYREX was sold to a company off-shore that uses a different composition for the glass, and it is prone to exploding violently under heat stresses that were no problem for the original PYREX.  It sometimes explodes as you are removing it from an oven.  (October 12, 2009)

Step 1: From Round to Flat

Pictured is a half-round piece of PVC I had left over from another project. The flat square was made by cutting a piece from the half-round and heating it while the water in the Pyrex cup boiled in the microwave for two to three minutes. I removed the cup from the microwave and used the tongs to pull the PVC piece from the very hot water. The tongs also helped to unroll the softened PVC so I could place the piece of wood over it and hold it flat against the countertop until cooled and firm. In the absence of a good supply of Plexiglass, some PVC flattened with the aid of a microwave and some hot water offers some impromptu versatility.

Step 2: My Brother's Tripod

My brother and his wife have a nice tripod for their camera. The tripod features a quick-release plate for speedy attachment and removal of the camera. The plate with the quarter inch x 20 thread screw fastens to the camera. Their plate is flat rather than stair-stepped, as you see in this photo from Google Images. Note the yellow lines I added.

Their daughter borrowed the tripod and forgot to remove the quick-release plate from her camera. They drove seven hours to our house on their way to a vacation before they realized they did not have the mounting plate they needed.

I flattened some PVC, squared it up, cut it to size, beveled two of the edges, and drilled for a bevel headed 1/4 inch x 20 thread screw. They were on their again way with a usable tripod.

Step 3: Microphone Holder

We got a new sound system in our church with new microphones. The new microphones require a different holder. I removed a strip from some white PVC according to the circumference of the microphone compared to that of the PVC. I heated the PVC in the microwave with a measuring cup and water to soften it. Then I held it tightly around the microphone while it cooled. (It is a good idea to wear gloves because of the heat.) When it was cooled, it fit quite well with just the right amount of tension to hold the microphone. See the red arrow.

Part of the old microphone stand could be used again. (Black arrow) I had some steel that was the same thickness as part of the old stand. (Green arrow) I had to weld a piece to it and attach the PVC with short screws. (Yellow arrow)

I used spray paint on the white PVC and it has not rubbed off, not even inside the holder. Some people have been very surprised when I explained to them where we got this microphone stand and from what it is made.

Step 4: Garmin Windshield Mount

This is an Amazon photo of the suction cup windshield mount for our Garmin GPS. I do not like it because it detaches from the windshield while I am driving. I want a mount that sits on top of the dashboard. I want to use the ball socket for this mount, too.

My wife is gone with the GPS right now, but, before she left, I measured the diameter of the ball mount with a caliper and did not disturb the caliper. It is about 17 mm or just a tiny bit more than 21/32 of an inch.

Step 5: Making Square Pieces

I set a fence on my bandsaw for 18 mm and ripped several strips from a flat piece like that shown in step 1. I need five thicknesses of PVC to gain a block of PVC a minimum of 18 mm high.

I did use pusher sticks to keep my fingers away from the bandsaw's blade.

Step 6: Preparing the Pieces

I tried gluing the five pieces together with epoxy, but that did not work so well.

I marked the center of each piece and drilled them so I could tap all five holes with 10-32 threads.

I had some 3/16 inch steel rod that I threaded with a die for 10-32 threads. The length of the threaded portion was just right at 18 mm.

I turned all five pieces onto the threaded rod and tightened them finger tight.

Step 7: Turning a Sphere

I cut the steel rod so it was only a couple of inches long and chucked it in an electric drill. I held the spinning PVC block against a spinning grinding wheel to shape it into a sphere. I stopped often and checked my work in several different directions with my caliper. I tried to approximate the same amount of drag I felt on the caliper when I sized the original suction-cup ball mount.

Step 8: Another Check

I scribed a 17 mm circle with a draftsman's bow compass and used it, too, to check my work.

In a couple of days I will be where my wife is and will check my sphere in the GPS's mounting socket. I can fine tune the fit the rest of the way with some sandpaper.

Step 9: The Stand

This is a drawing of what I have in mind for a GPS stand. It will be made of wood. The sphere and its shank could pull out of its hole for storage in the car's glove box. The same is true for the two dowel legs.

Update: I have made this dashboard mount for our GPS and it works great. I made it to be a little more compact than is shown here. The sphere I made from PVC was just a little oversize, but I held some sandpaper against it while spinning it in a drill and it works as well as the factory version. I may be able to supply a photo later.

Step 10: Base for a Dremel

I am thinking about a mounting base for my Dremel that would allow me to make spheres very easily by rotating the mount for the Dremel. Here you see a piece of PVC that has been softened and formed to the contours of the Dremel's underside. I am thinking of using a radiator hose clamp to fasten the Dremel to the PVC and screws to fasten the PVC to a wooden base.

Being able to shape parts from PVC softened in water in a microwave opens some very helpful possibilities for the home workshop.



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    32 Discussions

    Phil, Thank you so much for the interesting post (as usual).

    Can you first expand the idea behind the Dremel holder?
    I'm looking into creating my own Dremel press. Would you recommend any technique?

    Also, I was just wondering, about the GPS ball; Wouldn't it make more sense to form a mold from the original, and then cast a new shape from that?

    Keep it up,
    God bless - O>

    1 reply

    I am sorry. I missed your comment until now. When Instructables began lumping more than one comment into one e-mail notification, I began to miss comments below the bottom edge of the screen.

    I never did make a Dremel holder. The idea was a mount for the Dremel that worked like a stand. In this case the mount would be able to swing in an arc around the ball I was making to make the ball perfectly round. My idea was a form fitted clamshell held together with screws to clamp the Dremel into place.

    Taking a mold of the ball and casting it would be a possibility. A video came to mind of a wood lathe setup for making croquet balls. There was a curved metal ring around the blank for the ball. The chisel was mounted on the ring and could move around in an arc to form the wooden blank into a perfect ball.

    Hi Phil,

    Thanks for your ible. Can you please tell me what I could use to glue small curved pieces of PVC to the inside of a PVC pipe? I'm building a workbench portable LED light. The LED strip is mounted on the flat part of a round (ex computer) CPU heat sink that has a small fan inside it. The diameter of the round heat sink is slightly too small for the pipe.

    I want to cut some small curved pieces of a slightly thicker pipe that should work as packing to take up the slack between the pipe and heatsink.

    My question is: with what can I glue the PVC pieces to the inside of the body of the PVC pipe?

    Thanks for your help.


    4 replies


    What comes to mind immediately is the cleaner and glue used on PVC by plumbers. It is quite effective. But, it is also costly to buy small cans for just one little thing. If you have a friend who uses it regularly, you could "borrow" his cans of cleaner and glue. Otherwise, I would rough up the surfaces with coarse sandpaper and use a good epoxy. It should work well enough. Sometimes I use not glue to make rivets. I would drill a couple of holes through the two pieces of PVC with a little taper toward the outer surfaces and fill each hole with hot glue from both sides. When cooled it acts like a rivet.

    I meant "hot" glue rather than "not" glue. The auto correct on my iPad thinks it is smarter than a human. Most of the time it saves me from mistakes. Sometimes it creates its own mistakes.

    Thanks Phil - great to get your input. I really enjoyed your superbly right-brained hot glue 'rivet'

    Thanks. I have used hot glue rivets a couple of times and they have always worked well. The idea sounds a little low class, but has several advantages when that is what you need.

    I was not. Since you mentioned it, I see lead is used to stabilize PVC. I could not find anything about conditions under which lead in PVC might be released. Some items noted we use PVC for lines carrying drinking water, but seemed to let it drop there. What do you know for certain?

    Actually, PVC is typically only used to carry waste water *out* of the home (ABS is only used for this purpose too). Any lines that carry potable water will be made of copper (unless the plumbing is very old, in which case galvanized steel used to be used a long time ago). For lines that carry drinking water into appliances (like to feed your ice maker), those will be made of PEX (cross-linked polyethylene). Cool tip though... I'm going to try this out (using an old pan filled with water).

    I live out of town and we have our own well, it is newer and every drop of water in our house passes through PVC from the well to our blast tanks.

    Your summation of residential piping is not entirely accurate. PVC piping is routinely used for carrying potable water as well as DWV piping; the latter is typically "Schedule 40" piping. PEX tubing is also used for potable water, heating systems, and - thanks to its flexibilty - in under-floor radiant heat sytems (Which ROCK!). Older homes also used copper supply (usually with lead solder) and cast iron for DWV. REALLY older homes used cast iron for everything, some used lead for DWV.

    Newer PVC (Poly Vinyl Chloride) is lead free, look for ROHS compliant materials. Typically PVC is only harmful if it burns up. Warming it, as you did, in water shouldn't cause any harmful vapors or smoke which is where the real danger is. Lead free or not, PVC smoke is very harmful! I have spent the past 30 years working in environments where PVC is heated to melting point and extruded into various shapes. Don't take my word though, do some research on ROHS compliance, and MSDS sheets for various types of PVC from manufacturers of it.

    Be safe, and keep the nice instructables coming!

    Another wonderful tip. I'm not yet sure what I'll use this for, but I'm sure I'll use it.

    By the way, I'm sure you're familiar with the "burrs" that saw cutting pvc leaves behind. An excellent way to get rid of those is a rag dipped in acetone (finger nail polish remover). They wipe right off.

    1 reply

    Thanks.  I usually removed the burrs with a file or sandpaper.  I will have to try acetone.

    yea, burning pvc emits a harmful gasses, not sure about melting itthough

    Phil, This is a great Instructable. I stumbled upon it for other reasons, but it suits the needs of a different project I had in mind but hadn't figured out how to do. Thanks for posting it. Out of curiosity, why do you microwave instead of using a pot of boiling water?

    1 reply

    Thanks. I am glad it is useful. The microwave was more a matter of personal preference. I felt I would not need to wait so long for the water to reach a boil and I would not need to wrestle a hot metal pot. Since doing this I came into some birthday money that I spent on a heat gun, like a big hair dryer. It makes shaping PVC even easier.

    Not to be a devil's advocate but, isn't there a chemical in PVC that you would be exposing yourself to if you heat it?