3/4" Plastic Hole Plug

Hex & Slotted NPT Threaded Plugs

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Thanks Lyn, these are close but I was looking for something with a lower profile if possible. I may end up using something like these but thought I have seen some before with about 1/4-3/8 inch height. these look to be minimum 1/2 inch high.

Couldn't you take a belt sander with some 100 grit and knock them down to whatever depth you needed?

Or put a single edged razor in some vice grips, heat it up with a propane torch, and cut it like butter.

Whichever method you choose, do it with the plug in the hole and you'll have it perfectly flush.

Actually that is a possibility. It is close to the idea I was entertaining of using plastic threaded rod and just cutting it to the required length and using a dremel to make a slot. The problem might be that we need about 100 of them, so if I can find an off the shelf that works would be much better, but thanks very good suggestion.

Sorry for the seemingly stupid question, but how can you get any more low profile or flush mount than Lyn's first suggestion (Allen Head)?

Are they not made to suit your described purpose?

The image in the OP shows about three threads, so a thin (1/4" thick or so) plug. 3/4" NPT is 14 threads/inch.

Something that might preclude the sliced threaded rod idea is, there will be no taper and it will be nominal dimension. Don't know if this is a problem or not, but should be considered.

1/4 inch thick is good, the piece in my picture I have one but it is hollow in the middle(not a big problem but wanted a solid, flat 1/4 inch by 3/4 inch or so piece with a screwdriver slot in it. The hex units shown above are ok but they are at least 1/2 inch thick, I can modify the design for that but would rather not if possible to keep the overal dimensions small. I have seen something similar to what I am looking for but it has been years and do not know where they were from.

I might have misread part of your OP:

Is the plug a true 3/4" major diameter, or is it the size of 3/4" pipe? If it is true 3/4", what is the thread?

A 3/4" NPT plug Ø would be 1.05", 1/2" would be .840", and 3/8" pipe would be .675"

That looks like a hole plug for a Mulberry weatherproof box.

I know they make these plugs in Die cast Zinc and Stainless Steel, would that suffice?

I checked their on-line catalog but did not see any in plastic,

Might not hurt to contact a Mulberry factory rep, maybe they could provide a source for you.

EDIT - They come in 3/4"

Take a look at page 18 of this Carlon catalog

See that plug in between the lamp sockets, betcha thats "PVC material" just like the base plate.

The closure plugs are on page 19.

Hope this helps, good luck!

Just figuring out how to reply, but I believe you will find what your looking for from Heyco on this site.

http://www.mouser.com/heyco/

Good luck I hope this helps.

This looks like it.

http://www.facebook.com/notes/thomas-betts-bestseller-best-store/-best-price-thomas-betts-dplg-2-34-inch-red-dot-d-pak-non-metallic-closure-plug-/104472379666258

Good luck.

Perhaps the 'king of tools', a lathe, can be considered. First you should find a little lore, and a lathe to do the work (with or without operator).

Material 0.75" dia. LDPE/nylon,polyethylene etc one 10' length.

Tooling 60 degree tool (roughly) 0.75" NF die and stock (note that a small pitch error can be taken up by the plastiic's maleability). Pitch gauge. Hacksaw. Bandsaw.

Cut off a 2' length from the rod,chuck, and with ca 3" protruding from the chuck cut 0.100"deep grooves at ca 0.25" intervals. chamfer the end with the tool's side.

Using the die, thread up to the leftmost groove.

You now have about 10 plugs, separate them by parting or hacksaw; a bandsaw might be used too.

The slots could be put in before separating plugs using the bandsaw or a router.

Two hacksaw blades will give a wider slot.

The loose plugs can be held in a shallow 0.75" dia recess for slotting.

By following this path you will move from a shopper/ purchacing officer towards maker, that gain will stay with you.

I would try a plumbing contractor supply store .They make their own plugs sometimes.

What You are looking for is an electrical plug for an outdoor box. any electrical supply company should have these or even a big box store.

oilcan13

I was wondering when someone would suggest that

The small puzzle is what thread?

Conduit and pipe run different pitches - as do cameras, microscopes and bicycles.

There's another way.

I've made things like this out of JB Weld. A similar epoxy would work.

Put a light coat of thin oil on the female threads. Plug the back side. Warm up the epoxy in some hot water so you get a good flow. Mix and pour into hole. Tap body around hole to help epoxy flow into threads. As it starts to set, use a penny, flat head screw driver, hex head, etc, on the top. Allow to set completely. Remove.

Once the first one is done, you can use it to make multiple molds in wax. Then you can make as many as you want.

Or,

If this is the right size, but wrong material, use it as the "master" to make a mold.

oilcan the product you mentioned is the one I have and did get from my local electrical supply. The problem with it is it is hollow and actually the 3/4 inch I found might be too big. Kramarat your idea is the best so far. A half inch npt pvc cap will work but is too high, so I would have to cut it down, and the problem with the threading would be the holes because the taper thread I would end up threading the hole too far in, though I have a few ideas for that. I thought someone would have known a supplier for the thin plastic ones I have seen in the past that were used for things like button cell battery covers, etc. Perhaps those were custom made for the product they were designed for. thanks all.

You say "might" be to big; If the size is ok You can always fill the hollow in with some material to make it solid.

oilcan13

What about people who make plastic thread protectors? They might stick out too far though, as they don't have to worry about height.

I also have seen something in electrical supplies/boxes, but can't remember any details.

order some 13/16 plastic rod and take them to a machine shop -- or run them thru a die to threat them and hit them with a small grinder -- thread the whole rod and cut to lenght

Actually I think these will do but would prefer plastic, otherwise think I will try these as they will work well.

Actually my client is going to use this to hold a number of magnets in a hole. His concern is whether steel will affect the magnets or magnetic field. since I am not certain as to his end use for this I assume it is something to do with energy. If he stacks 16 magnets in the hole will the steel plug have a major effect on the magnetic fields. there are going to be many holes in a line (I assume opposite poles for each hole. I am very very rusty with magnetism but do not think it will be a major issue. any advice on this?

Actually folks I think this might do better but more expensive, what I think is an internal lock nut but these are for cameras, etc. I suggested standard retaining rings to my client but he does not want them. threaded ones would be better if anyone knows a lower cost source it would be appreciated.

If that is an indication of the radial fits - why not just a Circlip?

Pick a style, cheap as chips. 1 groove verses fine thread tapping, easy