[Newbie] threaded inserts

Kaylee Frye

Kaylee Frye

Registered
Registered
Joined
Oct 28, 2016
Messages
11
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!
IMG_0168.JPG IMG_0169.JPG IMG_0171.JPG IMG_0173.JPG
 
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
 
Last edited:
I do not know about metal threaded inserts. I have only used the one for wood.

I think power tapping the tube should be the fastest method. Use a spiral flute tap and some cutting fluid. Lots of YouTube videos showing this.

Are you centre drilling or spot drilling to start the hole? If not, this may be why the drill slides when you start. The flat web on the end of the drill can cause this.

You should try tweaking the table alignment on the drill press and replace the chuck if it has too much runout.
 
Are you trying to have the thread be flush with the surface? If you can accept a small flange, I'd look at Nutserts. They are Threaded Inserts that are installed like pop-rivets.
 
The wall thickness on the tube looks like it may be .120" ? With that much material I would drill and tap the thread. I use my cordless drill to tap material this light and even do the same on heavier material. Using the proper size drill bit and a quality tap is the key. After the holes are drilled I chuck the tap in the drill, and just dip the tap in the cutting fluid (I use a plastic spray paint cap) and go for it. It's quick and easy. Hand and eye coordination with the drill is helpful.

I don't use this method on something that needs more accuracy, but with a little practice you can do this.
 
As for Machining Classes, Community Colleges can be a good source for classes. Not sure how close it is, but it looks like Queensborough Community College has an Engineering Technology Program, which includes a "Mechanical Engineering Technology" Emphasis. Looks like the MT-122 class covers basic machining, along with foundry and welding.

http://www.qcc.cuny.edu/engtech/

http://www.qcc.cuny.edu/academics/docs/College-Catalog.pdf

"MT-122 Manufacturing Processes1 2 class hours 3 laboratory hours 3 credits Prerequisite or co-requisite: MT-111 Production techniques in manufacturing, including welding, casting and molding, forming and finishing process. Laboratory prictice in the use of hand tools, machine tools, and precision measuring instruments."
 
Is is possible to make a drilling jig with drill bushings to accurately locate and drill the holes? Then tap as suggested>

David
 
My question is this: If your drill press is not accurate enough to tap with, how are you getting holes accurate enough to meet your current needs?
If the drill is good enough to put a hole where you want it, then it is accurate enough to power tap with. Get some gun taps, and have at it.

From a business point of view (not to sound critical, this is meant constructively), it sounds like you might be engaging in a bit of "penny wise and pound foolish" thinking. It sounds like making holes is important to your business, pony up and get a proper drill press. Dumping $1k or more on a tool important to your work is better than adding time and complication to manufacture, not to mention introducing another point of failure.
Wish I could recommend a brand, I have a Jet floor model that is a POS, but it can still power tap. MSC sells Enco drill presses, dunno how good they are, but my Enco 12" bandsaw is pretty nice. Looks like they run $500.00ish, good chance you can pick one up at your local MSC and save some shipping.
 
Kaylee -

Rick Sparber (forum member) has posted a technique that might be of use to you. It does include welding, but you can grind the weld flat and even with the surface of your tubing:

http://rick.sparber.org/cfa.pdf
 
You must log in or register to reply here.
Back
Top