How to Make a Hole Smaller

Let's machine a permanent press fit! Math for calculating diameter tolerance is at 1:30.

[@saifialeem8255]

Pretty nice way, if the hole is small enough you can actually seal the hole with a weld bead then grind it and redrill. We used to do this in college works well.

[@McGuireMechanism]

Thanks, Saifi! Filling with weld is a good tip.

[@DeveloperChris]

This is what I do with a hole I have inadvertently drilled in slightly the wrong place. Fun Fact you can also weld a bit of metal to a broken screw to undo it even if the screw is in wood. I had to do multiple of these in some old floorboards I was reusing.

[@gomezinrome]

As a father of 4, I clicked on this video expecting something different

[@Officialmryuck]

Came looking for a guy smashing homeroom records but learned how to plug a hole 😉

[@McGuireMechanism]

Haha it's the off-season

[@rozijntje]

What you do is the following: start using metric units, you won't encounter this anytime soon again.

[@mikelastname]

Thanks for the great video. I normally just weld up holes if I have the right filler, but I like the idea of interference fit as well, and you very clearly explained the methodology which was handy. For that larger plug (0.002) would you need to press it in, or, would hammering still work? I also picked up the tip about putting shafts in the freezer for easier fit from the comments below, which is another thing to add to my arsenal of measure once, cut twice, techniques.

[@McGuireMechanism]

Thanks Mike! With a chamfer you can hammer a .002 press, but you might warp or scuff up your part. Some folks invest in a manual arbor press or a shop floor hydraulic press, which are gentler methods. The bigger the hole, the more forgiving it is with greater interference, too.

[@DeveloperChris]

Freeze the plug to make it fit easier.

[@McGuireMechanism]

Good tip, Chris!

[@dennisvandijk9759]

Love the fleetwood Mac in the background 👌

[@McGuireMechanism]

Haha thanks Dennis! That's my buddy Paul Erickson

[@dennisvandijk9759]

He’s doing a great job! That’s a super hard to play song

[@automaticprojects]

Neat tip. I would’ve thought you’d need a little TIG welding to make it fully strong. I’ve done the same thing with wood and a little glue.

[@McGuireMechanism]

Thanks Mark! Good tip on the wood. For steel-steel, no need for weld with enough interference. With similar metals, "galling" may also occur, where materials rub into each other and naturally fuse together. This is usually a problem, but not when we're trying to form a permanent press.

[@bdivi2000]

Easier and not requiring reamers and precision bars is to drill, tap and locktite a bolt.

[@McGuireMechanism]

Good idea! With that method, I might ball pean the opposite side before re-drilling to help keep the screw in.

[@thedevilinthecircuit1414]

I usually go .001" interference and use red Loctite in the drill rod as my gravy 🙂

[@McGuireMechanism]

I like it!

[@ehdeesign]

Good luck with a 0.002" interference fit!

[@McGuireMechanism]

That's the upper limit of the tolerance range for interference. Any lower with the reamers I can find would drop the lower limit too low. I agree-0.002" is not ideal, but that's not the target nominal value, and it works for me.

[@therealbadbob2201]

Shrink fit?

[@pen-nl1cm]

would not work cause you would have to heat the plate and not the rod. because you need to expand the metal hole in the plate which depending if you need the billet flat then heat could warp it

[@McGuireMechanism]

There is overlap in tolerance standards that use terms like interference fit, press fit, drive fit, force fit, and shrink fit. You could also cool the plug instead of heating the plate.

[@CivilizedWarrior]

@@McGuireMechanism was just about to say the same. You could potentially get a slightly bigger plug, and throw it in the freezer for a while, let it contract, pound it in, and when it expands you’ll get an even tighter fit. We used to do this with certain automotive bearings, like for pinions etc. Great video btw, faster and easier than pulling out the welder! I’ll use this tip next time I screw up, which I have no doubt will be soon! Lol.

[@McGuireMechanism]

Thanks@@CivilizedWarrior! Great point. I often throw shafts in the freezer (if they'll fit) just so things go together smoother too :)

[@AlotOfNothing-vp8en]

never heard of welding eh?

[@hannes3040]

Never heard of tempering eh

[@davidgraham2673]

Sometimes you just can't weld. This is a solution for one of those times. Good to know, and keep in your bag of tricks.

[@Dibulok]

Thank for a great video. Btw, imperial is so stupid. America PLEASE learn metric. Take care ❤

[@McGuireMechanism]

Haha thanks Simon.