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Paul Alciatore
01-10-2014, 03:15 AM
I want to slide a PVC pipe fitting on a piece of steel tubing. The tubing OD is about 0.883" with a generous tolerance/variance. I do not need a fluid or gas tight fit, just be able to slide it on. I can use some epoxy or other adhesive to hold it there for a nice mechanical joint. All the stress will be in the direction of pushing it onto the tube, not pulling it off. No rotational stress. So the adhesive just needs to fill the gap and prevent it from falling off when it is not being stressed.

The ID of a 1/2" PVC fitting (a Tee in this case) is about 0.836", again with some tolerance/variance. So I need to enlarge it by about 0.050" on the diameter. The enlarged section of the hole should end at an internal shoulder, much like the original hole does.

My shop is still in storage, so I do not have access to my lathe or mill. I do have a 20" drill press with vise and hand and hand-held power tools. So I need a way to enlarge that hole.

This is a two-off job so fancy, expensive tools or jigs are out of the question. The diameter is just a bit over the 7/8" drill size so it would be hard to find a drill of the proper diameter or to modify a larger (15/16"?) one.

Any suggestions?

plunger
01-10-2014, 03:30 AM
Don't understand what you need to do but I often use a heat gun or even burning newspaper to heat up pvc fittings enough to push on slightly oversize pipes or tubes. I also use a trick of heating the tube,mainly copper pipe with a blow torch and use it as a hole saw by just pushing it through the pvc. Cuts a real nice hole. This is just by hand pressure

RichR
01-10-2014, 03:44 AM
Hi Paul
Maybe a drum sanding bit from a Dremel tool.

Ian B
01-10-2014, 06:44 AM
Could you take a short bit of the pipe, file some teeth on the end and use it as a simple drill? You're only cutting 25 thou into the fitting, and mild steel vs PVC for 2 holes shouldn't be a problem. If the holes need to be a bit larger, bend the teeth outwards a little.

Ian

DR
01-10-2014, 07:22 AM
Heating the PVC with a heat gun and pushing in a mandrel of the required size should work. The mandrel doesn't need to cut, just expand the plastic.

Sun God
01-10-2014, 07:32 AM
How many do you need to do? Just the one, and I would say either the heat gun or dremel suggestions are the go.

More than say, 10, try the heat gun, and if it doesn't work, consider making a simple fly cutter for the drill press. Get a piece of round you can chuck up, cross drill it to fit a piece of round HSS you ground to a tool (say, like a broken drill shank), and drill and tap from the bottom for a retaining screw. Trial and error should get you boring a hole of the right size, and after that, you should be able to knock out multiples very easily.

mikem
01-10-2014, 09:38 AM
I like the idea of heating it up. Use the tube as a mandrel and slide the piece on, wiggle it on till it fits in your done!

firbikrhd1
01-10-2014, 09:41 AM
If I understand, the dimension you need is a little over 7/8" and the hole you in the fitting is a little under 7/8". If so, take a 7/8" hole saw, put it on the arbor backwards and run it into the fitting. The top of the hole saw is a bit smaller than the cutting end due to set in the saw teeth. It should fit inside the fitting and as you advance the saw backwards the teeth will eventually come in to contact with the inside of the fitting and enlarge it. It doesn't matter which way you have the drill turning, the PVC will cut even if the teeth are moving the opposite of the cutting direction. In fact it may work better that way. Installers of vinyl siding run a fine tooth plywood blade backwards in a circular saw to get a smooth cut on the siding.

Rich Carlstedt
01-10-2014, 11:25 AM
I believe what Paul wants is to bore out a Plastic T fitting to a size slightly bigger than 7/8" with only limited tooling.
A single lip cutter would be very difficult to control on flexible stock.
my experience with heating up plastic fittings is that they shrink, not expand, and if heated more, they become flimsey
and difficult to hold

Good question Paul !
a thought provoker

Rich

jlevie
01-10-2014, 01:32 PM
A 57/64" drill would yield a diameter of 0.891. It will likely cut slightly undersized in PVC when used like a reamer. Probably best to do this as a hand operation as it may want to grab. While it would be a bit expensive (~$70) for a two off operation a 22.5mm reamer would yield a diameter of 0.886".

Paul Alciatore
01-10-2014, 02:43 PM
I didn't think of heat. Hummm!

I think I will look and see if I have a 7/8" hole saw unpacked. If so I can use it in the drill press with the vise to rough it out. Then it should be easy to heat it and push it on.

I will let you know the results.

Thanks all.

darryl
01-10-2014, 05:15 PM
For two pieces- I like Ian Bs idea. Easy to file a few teeth, and the size is right. I would avoid heating personally, as it never looks the same afterwards. Maybe that doesn't matter, in which case it's probably the easiest and fastest way to do it.

CarlByrns
01-10-2014, 06:51 PM
I want to slide a PVC pipe fitting on a piece of steel tubing. The tubing OD is about 0.883" with a generous tolerance/variance. I do not need a fluid or gas tight fit, just be able to slide it on. I can use some epoxy or other adhesive to hold it there for a nice mechanical joint. All the stress will be in the direction of pushing it onto the tube, not pulling it off. No rotational stress. So the adhesive just needs to fill the gap and prevent it from falling off when it is not being stressed.

The ID of a 1/2" PVC fitting (a Tee in this case) is about 0.836", again with some tolerance/variance. So I need to enlarge it by about 0.050" on the diameter. The enlarged section of the hole should end at an internal shoulder, much like the original hole does.

My shop is still in storage, so I do not have access to my lathe or mill. I do have a 20" drill press with vise and hand and hand-held power tools. So I need a way to enlarge that hole.

This is a two-off job so fancy, expensive tools or jigs are out of the question. The diameter is just a bit over the 7/8" drill size so it would be hard to find a drill of the proper diameter or to modify a larger (15/16"?) one.

Any suggestions?

I have done this. Heat the the tubing and press on the fitting. Easy peasey.

Wheels17
01-10-2014, 11:34 PM
We used pvc pipe extensively in FIRST robotics teams. We'd slit large pipe lengthwise, heat it with an industrial heat gun, grab it with welding gloves, and flatten it on the table saw table. Not perfectly flat, but very useful. If you needed an angle bracket, heat and bend, let it cool. We'd heat some pieces 2 or 3 times and never saw any significant degradation.

Paul Alciatore
01-11-2014, 02:45 AM
Well, I was worried about the heat thing so here is what I did:

First, the problem, my shop chair had broken feet.

http://img.photobucket.com/albums/v55/EPAIII/Photos%20for%20Tips/P01x33_zps9fa8b530.jpg (http://smg.photobucket.com/user/EPAIII/media/Photos%20for%20Tips/P01x33_zps9fa8b530.jpg.html)

This is the second stool I bought from Wal-Mart and both of them had this problem.

I used a large counter sink to center the vise and Tee under the quill and bolted it down.

http://img.photobucket.com/albums/v55/EPAIII/Photos%20for%20Tips/P02x25_zps2a721d40.jpg (http://smg.photobucket.com/user/EPAIII/media/Photos%20for%20Tips/P02x25_zps2a721d40.jpg.html)

Then I used the counter sink to chamfer the inside edge enough to guide the hole saw a bit. I set the speed to about 220 RPM since this was plastic and I did not want to melt it.

http://img.photobucket.com/albums/v55/EPAIII/Photos%20for%20Tips/P03x28_zpsca34fa3d.jpg (http://smg.photobucket.com/user/EPAIII/media/Photos%20for%20Tips/P03x28_zpsca34fa3d.jpg.html)

I set the quill stop at 3/4" when the saw teeth were even with the top of the Tee. I used the same speed and the hole saw went in like a hot knife in butter. It was so smooth and easy that I thought it wasn't even cutting until I backed it out and saw the chips. I tried it on the stool leg and it fit fine. Apparently the hole saw had enough eccentricity to make a slightly over-sized hole. So I did the second one as the foot that appears normal in the first photo is, in fact, half broken.

I did trim off the ends of the Tees so they wouldn't stick out too much.

At first I was going to use 5 minute epoxy, but then I thought that the flexibility of rubber cement might be better as it wouldn't crack. So I ruffed up the legs with some coarse sandpaper and applied the glue. I put it on the floor to align the new feet and left it there to dry overnight.

http://img.photobucket.com/albums/v55/EPAIII/Photos%20for%20Tips/P04x38_zps6292ae83.jpg (http://smg.photobucket.com/user/EPAIII/media/Photos%20for%20Tips/P04x38_zps6292ae83.jpg.html)

Now, baby has new shoes.

Will it last? Only time will tell. I poured molded plastic feet on the other stool and they have not broken after several years of use. But they look like H*!!.

C_lazy_F_Guns
01-11-2014, 06:34 AM
Could you take a short bit of the pipe, file some teeth on the end and use it as a simple drill? You're only cutting 25 thou into the fitting, and mild steel vs PVC for 2 holes shouldn't be a problem. If the holes need to be a bit larger, bend the teeth outwards a little.

Ian
This works well, cut the teeth in the pipe just by hack sawing some saw kerfs in the end and it will work great. I have done it to drill holes in wood that are pipe OD and am always amazed how well it works, even works with copper pipe.

demerrill
01-11-2014, 11:47 AM
For similar applications rubber crutch tips work well, won't skid, and are readily available in several sizes in hardware and home supply stores.
https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1346&bih=1074&q=crutch+feet&oq=crutch+feet&gs_l=img.3...1771.8642.0.9529.11.9.0.2.1.0.52.398. 9.9.0....0...1ac.1.32.img..2.9.368.XR53KYLAAww#hl= en&q=crutch+tips&tbm=isch

David Merrill

Paul Alciatore
01-11-2014, 01:20 PM
I tried rubber crutch tips, also labeled as chair feet, once. It took the metal tubing about 0.000001 ns to cut all the way through the rubber and into the floor.



For similar applications rubber crutch tips work well, won't skid, and are readily available in several sizes in hardware and home supply stores.
https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1346&bih=1074&q=crutch+feet&oq=crutch+feet&gs_l=img.3...1771.8642.0.9529.11.9.0.2.1.0.52.398. 9.9.0....0...1ac.1.32.img..2.9.368.XR53KYLAAww#hl= en&q=crutch+tips&tbm=isch

David Merrill