Boring Head Set - Precision Matthews Media

Added: 2026-05-30

[00:00:00]Hi, I'm Charlie with Precision Matthews, and today's concept can be broken down simply enough that a caveman can understand it.

[00:00:09]This machine makes circle.

[00:00:12]This machine makes square.

[00:00:14]What if make circle on square machine?

[00:00:18]Boring head make circle on square machine.

[00:00:21]We start video now.

[00:00:23]I'll start by acknowledging that the circle machine is preferable for [music] boring.

[00:00:28]A boring bar on the lathe is going to be stiffer, easier to hit dimension with, and all around a better experience.

[00:00:34]But often you just can't fit the work piece in the lathe, >> [music] >> so you need to bore on the mill.

[00:00:40]We're demonstrating on this piece of round bar only because it's what we have, so you can save your comments that we should be doing it on the lathe.

[00:00:48]It wasn't in our video budget to buy a junkyard engine block to bore the cylinders.

[00:00:52]We spent all that money on the mullet wig and American flag overalls from a couple [music] videos back.

[00:00:58]I think it was worth it.

[00:01:01]Also, because I didn't feel like changing out the work holding, I just cut some flats on the round bar.

[00:01:06]Being a YouTube machinist is easy. No one's checking my dimensions. There aren't even prints that I'm following.

[00:01:12]Why was this part designed with flats on opposing sides?

[00:01:16]Because this shot was done 20 minutes before quitting time last Friday. That's why.

[00:01:21]Choose your own adventure as far as locating the center of the bore goes. I went with the humble wiggler, finding both sides of the hole in both directions and splitting the difference, but you can use a coaxial indicator if you're fancy.

[00:01:34]However you do it, you need to have the spindle lined up with the center of the hole, unless you have a more avant-garde concept of what round means. [music] If you're unfamiliar with the boring head, it's pretty simple. We take this glorified lathe tool, put it here for smaller bores, here for larger bores, and if we've got our brown pants on and want to make some really big holes, wee!

[00:02:08]Seeing this footage, you might be tempted to try and adapt this boring head as a fly cutter.

[00:02:13]Word of advice, don't.

[00:02:19]Any knee mill is going to have a power down feed that moves the quill down an adjustable amount for each rotation of the spindle.

[00:02:26]You can see where this is going.

[00:02:29]You simply engage the feed, or feed by hand if your mill's not equipped with power down feed, and the single point tool takes a chip from the inside of the bore, making the hole a slightly bigger hole.

[00:02:44]Apologies that you can't really see anything once the tool goes into the bore.

[00:02:48]I recognize that it might be kind of a dull shot.

[00:02:51]You might say that this footage is uninteresting, not engaging, wearisome, tedious, drab even.

[00:02:59]There's got to be a better word to describe that.

[00:03:02]Buh buh buh barren of any interest.

[00:03:07]>> [music] >> Now you just take additional passes, adjusting the swing of the boring head each time, until you're at dimension.

[00:03:16]Note that the hashes on the dial are in diameter, or the actual amount of material taken off.

[00:03:21]>> [music] >> So if you move 100 hash marks, or one full turn, it moves the head [music] 50 thou and takes 100 thou of material off.

[00:03:31]We introduced some new boring head options recently, so we now have both a 2-in and 3-in boring head.

[00:03:38]I'd consider the larger 3-in option to be the default choice, and that's the one we're using in this video. But there could be use cases where you would prefer the 2-in.

[00:03:47]For one, this picture shows the smallest size of bar for the 2-in kit on the left and the 3-in kit on the right.

[00:03:54]The smallest 2-in bar is more compact, so you can start with a smaller hole.

[00:03:59]So, if you're doing model engineering or generally just work on smaller parts, you might go with the 2-in.

[00:04:05]The 2-in is available in a brazed carbide tool shown on the left or high-speed steel on the right. And the 3-in kit is only available in carbide.

[00:04:15]Some people like to be able to grind profiles and clearances into the tool with just a regular bench grinder. So, in that case, you'd go with the high-speed steel option.

[00:04:23]But, carbide is available in both sizes if you want to go that route, and you can replace the carbide tips indefinitely if you're confident with the torch.

[00:04:31]There's no wrong answer here, and it's really down to personal preference.

[00:04:35]So, there you have it. Whether you choose to go large or small, carbide or [music] high-speed steel, we've got you covered making circles on the Square Machine.

[00:04:45]Now, this was just a brief overview of the products we have, and I have a lot more to say about boring head use and best practices.

[00:04:51]Make sure you're subscribed to the channel so you don't miss that video when I finally get around to making it.

[00:04:56]Thanks for joining us today. We'll see you next time.