[Newbie] threaded inserts

Rustrp said:
There are threaded inserts that are installed similar to a pop rivet. These inserts do have a small flange that's about .032" thick.

This link is for one type that I use occasionally. There are some specific things that need to be part of the design for these to provide long term service without problems. Primarily, the piece you are fastening to the threaded part needs to have a flat surface to allow the screw to keep pressure on the tapered fit so it doesn't loosen up.

https://www.nutty.com/Marson-Klik-Thread-Serts_c_479.html
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Kaylee Frye said:
Hi all,

I know this isn't exactly a machining question, but I'd like your point of view!
I make custom metal furniture, and more and more lately, we need very consistent threaded holes. I normally tap by hand, but some projects need more consistency than I can provide. I haven't been able to find machining classes yet, so I thought in the meantime, what would a welder do?

It has been suggested to me to check out threaded inserts, which I could just drop in the hole, weld, and sand the top smooth. Only problem is, the result is kinda ugly, not up to standards for fine furniture for us, and not even as accurate as I wanted. My first attempt was with standard weld nuts from McMaster-Carr that have a little flange. One way I tried was to just weld on the flange, which even if my welds weren't as sloppy, is a little too ugly for what we need. The other way I tried was to countersink the hole to fit the flange-- it ended up being a pain to do on my 1/8" thick steel and much less accurate than I wanted anyway. Didn't even both to sand it smooth all the way because apparently it was hard to keep the flange flush to the metal.

I think I'm going about this problem the wrong way, I need another eye to take a look.

Does anyone know of the kind of threaded insert that would be clean and quick? Do you think I should skip threaded inserts anyway and try threading on the drill press? I've been hesitant to try that out because our drill press is a little wonky- I don't think it is square to its bed and I've noticed the drill doesn't spin 100% centered and tends to slide sometimes while beginning the hole.

Also if anyone knows of basic machining classes in the NYC area, let me know. I try a lot of metalshop things on my own, but I honestly feel afraid to tackle the lathe on my own with Youtube University, but maybe it's not so tough to figure out? What do you think? Any advice is appreciated!

Thanks!
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Kaylee Frye said:
Hi all,

I know this isn't exactly a machining question, but I'd like your point of view!
I make custom metal furniture, and more and more lately, we need very consistent threaded holes. I normally tap by hand, but some projects need more consistency than I can provide. I haven't been able to find machining classes yet, so I thought in the meantime, what would a welder do?

It has been suggested to me to check out threaded inserts, which I could just drop in the hole, weld, and sand the top smooth. Only problem is, the result is kinda ugly, not up to standards for fine furniture for us, and not even as accurate as I wanted. My first attempt was with standard weld nuts from McMaster-Carr that have a little flange. One way I tried was to just weld on the flange, which even if my welds weren't as sloppy, is a little too ugly for what we need. The other way I tried was to countersink the hole to fit the flange-- it ended up being a pain to do on my 1/8" thick steel and much less accurate than I wanted anyway. Didn't even both to sand it smooth all the way because apparently it was hard to keep the flange flush to the metal.

I think I'm going about this problem the wrong way, I need another eye to take a look.

Does anyone know of the kind of threaded insert that would be clean and quick? Do you think I should skip threaded inserts anyway and try threading on the drill press? I've been hesitant to try that out because our drill press is a little wonky- I don't think it is square to its bed and I've noticed the drill doesn't spin 100% centered and tends to slide sometimes while beginning the hole.

Also if anyone knows of basic machining classes in the NYC area, let me know. I try a lot of metalshop things on my own, but I honestly feel afraid to tackle the lathe on my own with Youtube University, but maybe it's not so tough to figure out? What do you think? Any advice is appreciated!

Thanks!
View attachment 234631 View attachment 234632 View attachment 234633 View attachment 234634
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You might find a solution by using B F Goodrich Rivnuts. They have a flat head version that flush fits a countersunk hole. They are keyed and several installation tools as well as a key notching tool are available for installing them. I just googled RIVNUT (Not case sensitive) and found images for Rivnut. There is also a video, I think it's titled "Installing Rivnuts" which gives a very good demonstration of the tools and installation processes. They are essentially blind rivets and are available in dozens of materials, thread sizes and configurations.
 
You might get a better looking bond by using silver solder.
Jimsehr
 
First, welcome to H-M! I believe you will find a great bunch of people here that are eager to help with many issues.

There have been a number of great suggestions here, and I would like to build on a couple of them. Something that you may not be aware of, and no one mentioned, is that a tapping head can be mounted in a drill press. As you bring the quill down, the tap spins in the proper direction to tap the hole. When you reach the bottom and start to withdraw the quill, the tapping head reverses the direction of the tap and it backs out of the hole, nice and neat. Tapping heads are expensive ($500 and up), but you would soon realize that they are worth their weight in gold when one considers time savings as well as reducing the number of broken taps.

The trick here would be to drill your holes first, probably using a jig of some sort so that the holes end up in the correct spot each and every time. Next, you would want to countersink each hole, but only slightly, just enough to put a very slight chamfer on the hole and remove any burrs. Lastly, tap your holes, using either a tapping head or, if money is really tight, use a battery operated electric drill until you can afford to upgrade your equipment. You will break more taps using a hand held drill, but it works in a pinch.

In an ideal world, a production environment would have a drill press set up for each step of the process, but you could set up your drill press for drilling all of your holes in all of your parts first, then change over to the countersink and perform that step on all of your holes. Lastly, change your set up to set up the tapping head and tap all of your holes.

The ideas to use well nuts or rivnuts are great also, they are quick and work great. But as already mentioned, they generally prevent a flush mounting and I can see where that would create a visual effect that would not be acceptable. I believe your best bet is to continue tapping your holes, but make some changes to your process to improve time, quality, and the finished product.
 
terrywerm said:
Something that you may not be aware of, and no one mentioned, is that a tapping head can be mounted in a drill press. As you bring the quill down, the tap spins in the proper direction to tap the hole. When you reach the bottom and start to withdraw the quill, the tapping head reverses the direction of the tap and it backs out of the hole, nice and neat. Tapping heads are expensive ($500 and up), but you would soon realize that they are worth their weight in gold when one considers time savings as well as reducing the number of broken taps.
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I've used one and they are easy to use and fast. I don't own one because I don't do the production that would warrant it. I go with a drill/tapped hole when I can and only use the rivnut, threaded inserts as a last resort because they are time consuming, especially when there's significant quantity. I usually end up thinking; I can't believe it took that long. Years ago I used my Milwaukee drill but they coast (and just to be clear, coast not cost) a lot more than the battery drills do.
 
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And, even with that shallow hole, use a spiral point tap. That should eliminate any backing up to clear swarf.
 
Hi Kaylee,

I have two ideas:

First, I have a threaded insert tool like this:
https://www.princessauto.com/en/detail/45-pc-threaded-insert-and-riveting-tool-kit/A-p2925204e
I have used it with with good results. The insert gets installed in a hole and the tool works much like a pop rivet to collapse the barrel on the other side of the material (inside the tube in your case). So they can work in a blind hole with no access from within. I suspect it's like some of the ones mention above.

If you'd like to see better photos of the parts and/or how they look when installed, just ask.
These do however leave a small shoulder proud of the surface, resembling a washer.

refill inserts are available:
https://www.princessauto.com/en/detail/80-pc-sae-replacement-inserts/A-p2925501e
https://www.princessauto.com/en/detail/100-pc-1-4-in-replacement-inserts/A-p2921872e
https://www.princessauto.com/en/detail/80-pc-metric-replacement-inserts/A-p8533705e

I have not checked, but typically Habor Freight in the US and Princess Auto up here in Canada sell many of the same products.

Second, you could make your own nuts to go inside tubes. Barrel nuts or "cross dowels" like these:
http://www.leevalley.com/en/hardware/page.aspx?p=44238&cat=3,43576,45375,44238
are made to go in a drilled hole in collapsible wood furniture, but would work great in a round metal tube.
Perhaps something similar could be made from 1/2" wide by 1/4" thick steel bar to fit inside your square tube.
These may only be an option if you have open ends on the tubes to install them.

When converting a friends antique bed frame to a "day bed" (I cut the foot board in half and used it like arms connecting to the head board as the back of the new couch-like piece of furniture.) I made some simple steel bars that I drilled and inserted into the end of the round tube legs. They added great support and also ensured that the tube could not collapse if the nut on the other side was tightened too hard. Mine just had thru-holes, but you could tap them. I drilled and tapped a hole in the end of these bars so I could steer them around with a long threaded rod thru the end of the tubes. To be sure that my "spacer" did not move when the piece was disassembled for moving it, I used an angle grinder to make some small slots thru the outer tube and "plug" welded the spacers to the tube. The welds were then sanded as the entire project was to be painted. These plug welds could be small and done thru another drilled hole, as they do NOT need to hold any weight.

Please let us know how you make out.

Good Luck!
-brino
 
System used in industry is called flowdrill, it can be used in an ordinary pillar drill, and uses a tungsten carbide "drill" which actually heats and flows the metal into a hole which is about double the thickness of the tube wall, thus giving you more room to get a decent thread in, then machine tap with a tapping head, or even a cordless drill with some tappiong compound, but you will have to degrease before painting. Hope this helps!
Phil
 
If you can find one there's a drill attachment for tapping with them by hand . I have one and it indispensable for just what your doing. It's a hand clutch with collets up to 1/2" taps. You hold the pressure in your hand to tap release hand hold the other half and it reverses. They also made them with screw driver ends. I think ridgid was the brand . For your press versatapper used to be fair priced don't think they make them any more. Lots of good used tapping heads around.
Just looked on eBay , pair of procunier tap heads with up to 5/8 " tapping down to I guess 6-32
Look very good for the pair $200.00
Others on there from $50. The hand held was called push pull by ridgid
 
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hermetic said:
System used in industry is called flowdrill, it can be used in an ordinary pillar drill, and uses a tungsten carbide "drill" which actually heats and flows the metal into a hole which is about double the thickness of the tube wall, thus giving you more room to get a decent thread in, then machine tap with a tapping head, or even a cordless drill with some tappiong compound, but you will have to degrease before painting. Hope this helps!
Phil
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Hi Phil, Thanks for posting that!
I'd not seen that process before and I now I can say I learned something today.
-brino
 
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