Making A Rotary Broach - Cutting Hex Sided Holes (DIY)

G'day everyone,
In this video I will be showing you the journey that I undertook to try and cut my own hex sockets. To do this I need to make use of a rotary broaching tool. There are commercial versions of this tool, but they are out of my price range for a hobby shop, so I decided to make my own. This will be a rotary broach tool for the lathe.
Making one should be a pretty straight forward job, but there are fine details that need to be done correctly in order to do this correctly. It took me a few weeks and several revisions to make this work. I hope you enjoy this video.
The two links below are well worth checking out. They provided me with a useful direction to go in when designing this tool.
The Recreational Machinist's Video - • Rotary Broaching a Hex...
mikesworkshop.weebly.com/
Timestamps
0:00 - Intro
1:06 - Making The Tool Housing
2:34 - Machining The Housing
3:48 - Machining The Shaft
5:06 - Machining A Backstop
6:21 - Finishing The Housing
7:16 - Cutting The Dovetails
8:02 - First Assembly
8:45 - Making The Broach Cutters
10:17 - Adding The Ball Bearings
10:48 - First Test Cuts
12:00 - Making A HSS Cutter
12:54 - Using The Rotary Broach
#DIY #Machining #RotaryBroach
Mill - Sieg X2.7l
Lathe Sieg c3 7x14 Mini Metal Lathe

[@BloodThunda]

HSS reamers will leave nice finish if you slow them down dramatically. I see a lot of people making this mistake. It has 6 flutes so it doesn't need high speed to keep it lined up with the hole as its fed down the pre drilled hole. Slow feeds & speeds with reamers. Also, use cutting fluid and not coolant, try this next time.

[@troytaylor9836]

If any tool is leaving a bad finish you should look up the speeds and feeds. These are also for ideal machining conditions, any slop in your spindle, work or tool holding will reduce your tool's effective speed, so don't be afraid to play with your speeds.

[@BloodThunda]

@@troytaylor9836 Agreed, most of the tool suppliers(or at least here on my side of the world) have like a book that is not only a catalog of their tools, but also recommended feeds and speeds. Beware though, some books are very nice and already have the feeds and speeds worked out for you. Some books will give very little info which leads you to work out everything. Also like Troy mentioned, its not to say that the recommended speeds & feed are gonna work 100% for you, so play a bit and you should eventually see a pattern to what the machine likes. But point being, you should be able to find the "proper" feeds and speeds from the manufacturer of the tool somewhere.

[@joesikkspac7904]

Yeah, that reamer was going way too fast and feeding entirely too slow.

[@1crazypj]

@@troytaylor9836 I was thinking the same thing, don't think I've ever seen a reamer run that fast, looked like drilling speed? Published figures are almost always for industry where tool life/production rate is the main criteria. It's a trade off. For hobby use, it may be better to run a little slower cutting speeds or feed rates so tools last longer, particularly as most hobbyist's are in the 'ten thou' range of cutting depth and feeds and few have the ability or knowledge to re-sharpen cutters

[@mattw7949]

I'm no pro, but I recall a guideline of half the speed and double the feed for reamers compared the the S&F of the drill. Also don't let it loiter in the hole... once you hit depth, get 're out of there.

[@timothypetroulakis62]

A little tip on the reaming, slow your spindle, feed and you NEED to use some cutting oil, reaming dry is like tapping dry. Oil will improve your cut an unbelievable amount

[@oberender64]

Only slow down the Spindle not the feed.

[@benargee]

@@oberender64 why? You're making it remove more material per revolution.

[@smashyrashy]

Reaming should be half your drilling speed and more coolant than drilling its common sense

[@knightfall7534]

Hey, also, if you’re gonna use a reamer and want a more precise and consistent diameter, stop the reamer at the bottom of the hole, and bring it back up while it isn’t spinning, this way you won’t take off more material and make your hole bigger on the way up, also the finish is much better as there will be less scratches.

[@AlessioSangalli]

@@knightfall7534 exactly, I was thinking the same,

[@TheLastTater]

I love that you share when things don’t go as expected. Some of the best channels show that. Great job, you constantly inspire me to do more with my mini lathe

[@brucematthews6417]

One of the easiest to make but clever for it concepts I've seen. I wondered about the required offset angle until you mentioned just angling the tool post a degree or so off square. that turned on the light over my head! Like Deon below I also get fine results from my import reamers by using cutting oil, instead of coolant, and lower speeds. And don't feed it in overly fast. Feed it at roughly the same feed rate as a drill.

[@nexusofice9135]

Something about making your own tooling is always satisfying.

[@intellectualiconoclasm3264]

I not only enjoy your craftsmanship, I revel in your dry and self-aware wit.

[@larrypalmer7136]

Very well done video and very impressive resourcefulness with impressive results. Your channel has become one of my favorites for innovative and original ideas.

[@jacob_90s]

11:15 THANK YOU!!! It always seemed to me that a rotary broach shouldn't be able to work, and that finally explains why it does.

[@ArSeeStuff]

Love your work - and your 'can do' approach. It's refreshing to see failures turned into success, and the reasons for each. 👍

[@tcurdt]

This looks like magic. Would love to know a bit more details on why this actually works.

[@stevewatts3502]

Same brah, I trawled the comments and rewatched. I figured it's going in at 1 degree OFF the centre line ...sooo, it (um) kinda "nibbles/wiggles?" it's way in. (best guess 🤞)

[@BarackLesnar]

​@@stevewatts3502 yep that's it

[@damustermann]

I thought you're really going to file the stock. Even better, that's a neat little trick to get a cut started!

[@danshepler9933]

When I wanted to make 1/4" hex I used the rear end of a Phillips head drill bit. Place it in a drill and use another mini grinder to concave the rear of the bit, it leaves the edges sharp and I was then able to drill a round hole in material and then tap the "broach" in making my holes to accommodate any drill bit.

[@alext8828]

Do you need to use graduated sizes or can you do it all in one pass?

[@SweetTooth8989]

Was going to mention this too. I've done the same and it works well. As long as you aren't using cheap hex bits, something from a good brand name, it should be made from CroVan, S2 or A2 tool steel. Just make sure to not get the bit too hot and you're good to go.

[@FCleff]

Thank you for sharing and sticking with this project and working out most of the design problems.

[@brucewilliams6292]

This was really well done. Thank you for putting this up.

[@nutgone100]

This is one of those tools I just know I’m gonna have to make as they’re still too expensive to buy. Some good ideas here, so thanks for having a go & taking the trouble to video it for us.

[@MachiningwithJoe]

Excellent video dude deciding to make your rotary broach into a tools holder is genius and very unique. A rotary broach is on my list of tools to make soon. Keep up the good work 👍

[@xmodalloy]

Just a recommendation, but you should really run reamers a LOT slower than that.

[@Smallathe]

Very nicely made. Looking forward to see more updates on this.

[@TheRecreationalMachinist]

Great job, and thanks for the shout out! 👍 🇬🇧

[@shipsofscale]

Nice. I always enjoy watching your projects. I learn a lot.

[@obe726]

Nice work. I really like that you are building your own tools and parts.

[@homemadetools]

Good work. We shared this video on our homemade tools forum this week 😎

[@WorkingViews]

great look at the process. thank you for sharing!

[@axa.axa.]

I think I probably can watch all your videos and find a good reason in each to tell you to get a portaband saw already

[@savagestyle124]

Im a toolmaker at polygon solutions , not bad , your issue is speed and feed to have the broach cut to size and closer finish, but the mechanics are correct.

[@artisanmakes]

Thank you, it seems to be like this. I might give it a go in the sherline since I have better speed control there. Cheers

[@robertwalker7457]

Nice work, great innovation.

[@carramba86h77]

I really don’t understand why you don’t have more followers! Your content is great

[@monkeyzeetube]

wow..very resourceful..well done mate!

[@nicholaszimmer663]

Your like This Old Tony from downundaah.

[@bobjimenez4464]

nice tool making video....Thanks!. when you're buying your wobble broach setup for Rosan lock ring serrations, don't forget to buy the gauge too.

[@williamweesner1191]

Mad skillz. Love your videos.

[@josedias4664]

Muito bom, ficou ótimo parabéns.

[@davidtaylor6124]

Nice work!

[@MidEngineering]

That was a really good idea to make this to mount in the toolpost rather than the tailstock. So much simpler to make (a friend of mine made one out of an old rotating centre), you can experiment with different angles (1.5 deg. might be better than 1 deg.?), & you can easily compensate for different lengths of toolbits. O.K. it won't work in a milling machine but you probably don't need to do that anyway!

[@davidrule1335]

3:12 not to nit pick you( I find your videos very interesting) But I'm gonna say that was 4 times to fast with the reamer. And flood it with cutting oil.

[@artisanmakes]

Thanks for the heads up. It was about more than half the speed of the 12mm bit bit I think that was still too fast. :)

[@angelusmaker]

@@artisanmakes The rule of thumb I was taught as a machinist is 1/3 of the RPM used to drill the hole. Same for anything with a 45° taper, such as dovetail cutters. There are more accurate calculations in my machinist's handbook, but the rule of thumb has served me well enough :)

[@forrestcarroll9350]

@@artisanmakes Reamers also want much faster feed than drills. Often 2-3 times as much.

[@ErikBongers]

Now I'm confused. Which is it? Reamer faster...or slower than a drill? (And lots of chip-clearing, that I know.) UPDATE: Oh, I misread: slower speed, but faster FEED.

[@rackdevelopment]

How fast were you running the 12mm drill out of curiosity? Generally on a Bridgeport I would be running a 12mm around 300-500 RPM

[@scooby8567]

a great project man

[@dylanschmidt4166]

Much much slower with the reaming, as well as one plunge, don't peck at it. Some oil would help too. Awesome video!

[@ZlodieIzZaholustia]

Большая работа с отличным результатом!

[@lucasandri5462]

A great project! Probably you'll already know but This Old Tony has 1 or 2 videos about making a rotary broach. There's a particular feature on the rotating part as the broach isn't perfectly centered and rotates at a very slight angle. This provides a better cutting action. It is difficult to explain in words but as you see it it is very clear. Good work as always!

[@artisanmakes]

I did mention in the video that it's kicked off at a 1 degree angle

[@letsgoBrandon204]

I sparked my first hex socket the other day at work when I had bugger all to do. It was a little on the small side but a 3mm hex key just about went in. It would have been much easier to make the electrode if we had a dividing head. I had to use one of those crappy little spindexer thingies.

[@jadymulqueeney]

Brilliant, thanks, very interesting

[@ludditetechnologies]

Well done.

[@ericrichardson3332]

Looked pretty good , a few more tweaks with better tolerances and a little smaller cutting bit and you'll be making perfect hex screws and bolts keep at it

[@artisanmakes]

I made better cutters from silver steel and it really improved the results compared to the hss cutters

[@daniloagostini4156]

Brilliant!👏

[@aubrymacielpereirafilho3017]

Aprovado!!!. Valeu muito obrigado!!!.

[@NicksStuff]

These are magic

[@horsetowater]

Bravo!

[@lawmate]

Great work there. I made a tailstock mounted broach and it works ok but it wants to cut a spiraled broach. Have you had any issues with a spiral cut? I can get around it by reversing the spindle direction every 5mm but it's a bit of a pain. You might wanna add a thrust bearing as all the force is axial too. Thanks for sharing

[@Tammy-un3ql]

stunning.

[@artisanmakes]

Thank you! Cheers!

[@MadHatter123456]

A small bandsaw - even one of those portable ones - would be such an addition to your shop. Almost feel bad for you whenever you're cutting raw stock...

[@robert5]

vary cool. I did wonder if these could be made well enough to work. What I have a real need for is cutting internal splines for a Polaris RZR XP 1000 rear CV axle to slide into. No one makes any type of shaft I can buy. I do have a rotary table. I also have some dumont key way broaches and eyeing those, I wonder if I would make a spline cutter using a round key way style broach and a smaller key way cutter re-profiled as a spline cutter. Then inserted in a bored hole to cut and then rotated for each spline. Or would a re-profiled carbide boring bar work better? Guess I will simply need to try, that will be the fun part. Eyeing this rotary broach I wonder if I could make a rounded button with all the splines cut and mount it at an angle like this and cut all 27 splines in one smooth plunge cut. OMG that would be so cool. I'm guessing I would need one heck of a strong machine for that. Maybe a really big lathe. hmmm... no. I will just cut to the chase and start looking for a plunge EDM I can afford.

[@rtkracht]

Just started using Shapr3D. Wish you’d start documenting some of your work via some CAD software. You might even be able to sell some of your designs and buy a bandsaw!

[@cobre7717]

Make a power hacksaw next! You would enjoy it.

[@bjondersson]

Thanks for a well made and inspiring video! Do you think it would it be possible to make the cutting tool from HSS lathe blanks, or would they not be hard enough?

[@artisanmakes]

Thankyou. As I understand it most commercial broach cutters are made from M2 hss. As long as you can shape it they should be fine. If you can I'd buy round hss blanks or silver steel.

[@TheMrJaagoo]

Is it a rotary broach though, or just a broach that happens to rotate? I can't see what feature in your design would cause the required eccentricity besides runout from the chuck.

[@Troggination]

My guess is that he rotated the tool post to get just a bit of eccentricity, but it’s not clear

[@KayleeKerin]

@@Troggination He stated before the first cut that he put the tool at an angle to the centerline.

[@Troggination]

@@KayleeKerin oh whoops musta missed that.

[@JeffreyJamesMusic]

I keep thinking about how to make a 1/4” driver bit holder. I’d love to make a bolt with an extra deep hex socket and a magnet inserted inside. I doesn’t exist and it would be cool if it did: a “bolt” that can convert anything onto a .25 shank bit bolder by threading it in and using a set screw on the side.

[@DolezalPetr]

pretty good not gonna lie

[@horsetowater]

Could the dremel concavity work affect the existing heat treat for the broken drill version? Nicely done!

[@artisanmakes]

Always difficult to judge when dealing with hss since it loses it temper differently to carbon steel. I am quite certain the answer would be no, we don’t let the metal get that hot here

[@lohikarhu734]

I wondered if the thrust bearing (the end millp would be better if made flat, with a good polish, for lower contact pressure on the brass shaft...

[@JeffreyJamesMusic]

This makes me want to buy you a portable band saw for cutting that thick stock 😂

[@David_11111]

yay, your workshop tools mill lathe is there a list ?

[@electro_genius]

Очень интересно, я хочу такую конструкцию повторить! У меня почти такой же токарный станок как у вас 💪👌

[@HM-Projects]

Nice tool build, hss co drill bits could also be repurposed for this.

[@paulmeynell8866]

Interesting, I wonder why it needs to rotate, would think you could just push straight in? Spinning seems to have no effect?

[@juli1563]

Hello. Really nice Video. But you have an convertional miling maschine. You have to watch out in which direction you drive the workpeace to the milling cutter. Only counter run on this milling maschine. If you dont to it you spidel will be demaged in a very small time.

[@rackdevelopment]

I woulden't say it would damage the spindle, but it could be done I suppose, it's more that the rigidity of the machine and it's size should only be using conventional milling cuts, not climb milling.

[@davidrule1335]

I wonder if you could make a die, heat the bolt material and forge a hex into the head. Then machine as desired? js.

[@pakosta05michal37]

Lâu quá rồi mới nghe anh Đức Phúc hát, thích quá đi thôi.

[@Hawthorn619]

What source for green vise jaws? Also, have you tried a high-tension hacksaw? Great Vid!!

[@artisanmakes]

They’re just plastic soft jaws. You can probably buy them online

[@Ensign_Cthulhu]

It's all fun and games until you get married to a motor mechanic who keeps losing her 10mm sockets and asking you to make her new ones.

[@user-ow1jh8yb5j]

Someone buy this man a power hacksaw

[@BraxtonHoward]

Would love to see the footage from failed attempts. To see what caused the failures in better detail.

[@wasdaletimelapse7658]

Great video and thanks for sharing. I have no experience whatsoever with engineering or metal work and I am intrigued as to why the piece you are cutting into needs to be rotating, why can’t the cutter just be pressed into the undersized hole?

[@pontiacg445]

Between the 1 degree angle the tool encounters the work and the three degree of angle cut onto the broach, only one cutting edge on the broach is cutting at any time. As it rotates, each cutting edge is doing some cutting. You could probably just plunge broach a hex key, but you'd run into problems with blind holes and nowhere for the chips you are making to go. Plus, you'd have a very hard time doing that on machines of this scale, the pressure required would easily start deforming the frames, and I doubt you'd get any chuck to hold. Pretty sure you can see the stock slipping in the chuck (13:00) when using the rotary broach even, takes a lot of pressure even with only one cutting edge...

[@jensjohnsen9296]

I think you can use a reciprocating saw with a good blade for metal cutting instead of doing it with hand power, and that shouldn't be too expensive

[@JacobTJ1]

How does it work, and explanation would have been very nice

[@rickgledura3194]

Very interesting I still can't see how with that spinning it can cut a hex hole

[@AlessioSangalli]

Very nice work, just a question: at least twice you chose to do things a certain way because you didn't have the proper materials at hand, and in both cases you had to re-do everything, probably taking days of work. Why not get the right materials upfront?

[@artisanmakes]

If your referring to the cutters, they really only take 10-15 minutes to make. I did it this way because I have lots of hss shanks on hand and it is nice to find a use for them. I would have used silver steel if I had to but the hss worked. Easy way to save $20 or so. You can do it however you like if you make one. Cheers

[@kde5fan737]

I really don't understand why both pieces need to spin/turn. Can the same be done on something stationary like an arbor press or hydraulic press?

[@bazzaf246]

Hiya Artisan can you please provide some information on the bearings you used? were they angular contact? interested in trying to make a rotary broach for myself :)

[@artisanmakes]

Hey mate, from memory I used a set of 5700 bearings. I only used then because they were left over from another project so don't feel as if you need to use this specific size. These aren't thrust bearings, the thrust force is taken up by that rounded pin at the back of the assembly. Best of luck.

[@bazzaf246]

@@artisanmakes thanks for replying!

[@Randorf100]

I still don't get it how can you do the cutting to make the hex cut when it is rotating like it was drilling but is not so explain to me please how does it works

[@matthewpeterson3329]

Is it possible that your final result is a bit loose because there is some runout in the Jacobs chuck? I'd bet your tool itself is correct. Great job on this video... always a fun watch!

[@artisanmakes]

The run out shouldn't matter much, I made everything a little loose to lower the stress on the cutter. The cutter was just a little bit oversized

[@thisolesignguy2733]

I think your next project should be a power saw, I can just imagine your arms are jello after cutting those parts by hand lol

[@andersgrassman6583]

It would have been nice if a few graphics with lines and angles were imposed on the video fotage for the actual cutting use at the end. Because at least I myself don't understand at all how this tool works. The video fotage doesn't tell me anything, I don't understand at all what is going on. And why is the tool rotary in the first place? That could be touched upon as well. I suppose just ramming a form broach into a hole, like with keyholes, requires a lot more force and probably a number of consecutive sizes of ramming broaches.

[@sblack48]

Perhaps the next thing you should invest in is a cheap import band saw before your arm falls off. Nice work.

[@omairalkhairy1]

Faster is better for rotary broaching, if you want to do steel use carbide to make the broaches, broken end mills are the best. You will need a grinder for that though

[@Tealyc]

Pls use lube while reaming! Will provide you with a much better surface quality! It's even a difference between water and oil tho. Oil makes it slightly bigger in diameter!

[@Lucas_sGarage]

Just as a side note, the green stones aren't meant for steel, they are usually meant for plastic, if you use those, they will ware out really fast

[@artisanmakes]

Thanks for the heads up. These are just cheapo ones from a $15 set of rotary tool accessories. No wonder why they didn't last long :)

[@Lucas_sGarage]

@@artisanmakes you are welcome, btw for a beginner, from Alibaba, which mill would you recommend?

[@youpattube1]

This is new to me, so I don't mind asking a dumb question. If they are both turning at the same speed, why turn them at all? Why not just push the broach in ?

[@artisanmakes]

kzbin.info/www/bejne/f4Wbh4uHerCtpdE this video explains it well. Difference here is I spin the work not the tool

[@geoffjan1]

I can’t understand how it cuts the hex hole both parts are moving together? What am I missing?

[@UncleKennysPlace]

Unless I missed something, your broach isn't set up the same way commercial broaches are; their toolholder is offset, and holds the tool at an angle that effectively gets the center where it should be. That way there's a decidedly "wobbly" action. See ToT for videos of that cutting action.

[@grahameblankley3813]

You need to look at video at 11.10 he explains it.

[@MidEngineering]

Rotary broaches only wobble when used in a milling machine. You can't really see what's going on when they're used in a lathe.

[@joell439]

👍😎👍

[@thebonermaker]

you should look into getting some coolant concentrate for your cutting fluid to avoid rusting your tools. a little bit of it goes a long way.

[@artisanmakes]

This is mixed with www.machineryhouse.com.au/S090A?gclid=Cj0KCQjw5-WRBhCKARIsAAId9FmgtrJdooUUsBGqLrvO2I7g4i1I-T0xnApTu2i0elTQyuKK4GW_ChEaAkC7EALw_wcB at the specified ratio

[@Tinman97301]

👍💯👍

[@ChristopheD_]

hi. Why do you turn your lathe by hand when you cut threads?

[@maxheadroom1506]

i do that as well as my lathe it would be too dangerous to disengage the gears while running. plus you have more control albeit more slower.

[@rogerrascal8632]

if you used some oil with your reamer (and your drill bit) and slowed the speed down, you would get a much better finish....

[@hieronymus..bosch8532]

I did this by just pressing , using titanium for cap screws . It worked fine . But stainless is a nightmare & it needs to be rotary cut

[@bretthays2674]

What is the cutting tool you used to cut the angles on the dovetail?

[@artisanmakes]

a dovetail cutter

[@bretthays2674]

@@artisanmakes ask a stupid question, lol. Thanks.

[@hoernst2762]

Glückwunsch

[@kurzschnautzert180]

Warum lässt er die Maschine laufen?? Da kann ich doch gleich den Stempel mit dem Reitstock in die Bohrung pressen.Völlig sinnfrei!!

[@artisanmakes]

@@kurzschnautzert180 Might work for you, but hat wouldn't work on this size lathe.

[@connorjohnson4402]

@@artisanmakes Im guessing he missed the 1 degree offset on the tailstock, alot of people seemed to miss that as well since its not super obvious in the video.

[@laststand6420]

Is there a reason you use a hacksaw rather than a rotary cut off tool(grinder with cutting wheel)? It just seems like the hacksaw would be painfully slow. Edit: For heat dissipation purposes I suppose?

[@artisanmakes]

Grit from the cut off wheels. It gets thrown at the camera, the lense and it it get on the lathe and mill ways which I would like like avoid

[@laststand6420]

@@artisanmakes Makes sense, it does throw a ton of junk.

[@fettersbuiltco]

Well, the reamer needs to be run with oil, and with half the speed and twice the feed of a drill. You need to run coolant or oil with all your cutting using drills and reamers.

[@artisanmakes]

I did use oil on the reamer, bit fast though

[@bryanknecht513]

pls tell me that this collant is not just whater. you have to mix it with oil, it shoul look whit ish.

[@jacobmiller6664]

It is coolant, he has mentioned it seems too diluted at the recommended mixing ratio, and that he thinks it looks too watery, but he says it works well.