Knurling

[@GunsnCars3]

Im no machinist but I helped my great uncle build planes, who was one. Every time I used and kind of a chuck, be it drill, drill press or lathe he always made me tighten every side of it. That way you are centered, and your work piece or drill bit will not spin. Keep up the good work and I hope this may help you in the future.

[@valy5684]

It looked like a chuck where all the jaws close at the same time at the same speed. If you're using a 4-jaw chuck you usually need to tighten them individually for more precision. 3-jaw chucks (and apparently 6-jaw chucks; never seen one before) usually have a simultaneous tightening mechanism. But I do agree with you. I mostly use 4-jaw chucks for their higher precision expect for some quick turning (replacement screws, etc)

[@289pinto]

Your great uncle was a plane? 😎

[@stevo68]

GunsnCars3, you're right, it is best practice to do that.

[@kaikaikikit]

Had no idea of how Knurling was made before i watched your interesting video. I was searching for how to model Knurling pattern in 3d software. Always interesting to discover how our daily surrounding tool are made. :-)

[@chaneyhouk5950]

I’m going to school to be a machinist, I finished my first year with a B average, but I don’t have a summer job at a machine shop, so I hope I don’t forget everything for the second year.. before this year I never touched a machine in my life. Wish me luck.

[@I_guess_its_abhishek_here]

Good luck

[@chaneyhouk5950]

Abhishek sinha thanks. I graduated and got a job!

[@SeeHowItGoes]

@@chaneyhouk5950 do you enjoy it?

[@chaneyhouk5950]

@@SeeHowItGoes yes. Still work at the same job.

[@ziggyboogydude1]

@@chaneyhouk5950 congrats! i just cut my first chips today in class, hopin i get better than i am now lmao

[@SavageViking]

Engineering question: Does the diameter of the knurling tool have to be equal to the diameter of the shaft being knurled? It seems to me that if the circumference of the two is not the same then each rotation would cause destructive interference with the previous rotation.

[@alessandroandrenacci2372]

"The same" seems to me a too strong condition, i would say better : "integer multiple" ?

[@1kallay]

That's what l wondered when he turned it up to really bloody fast, now l just wonder if somebody is going to answer it properly

[@53rounder]

no

[@SirEpifire]

Older video I know but this is such a cool process to see! Honestly makes me really want to invest in a lathe. Never understood what knurling was before (or even what it was called!).

[@balesmachine]

I've been knurling for 30 years, and have always had problems with knurls that have to be forced into the stock from one direction using the tool post and cross slide. Once I got a scissor style knurl, my problems went away. Scissor style knurls don't apply any force on the tool post. The problem I would get is I would get double hits, where the knurl would hit in between the previous mark as the stock rotated, thereby doubling the knurl pitch. With a Scissor style knurl, this is eliminated by clamping the two knurls heavy into the stock BEFORE turning on the lathe. In this manner, the first dents are deep enough so that on the next rotation the knurl falls right into the previous dent, thereby eliminate the double hit. Try this and you will like it. It is much more dependable - for me anyway.

[@MilanDupal]

Thanks. I am building my own scissors knurling tool now.

[@FradyKatt]

Stans world Scissor Knurl Explained kzbin.info/www/bejne/f2rWoaRqdttners

[@JR-rc6vd]

Tip when u at the end of your knurl lenght just shut off machine dont back tool off that way if u need to go deeper u keep the same pattern

[@mohdaslamqureshi3750]

School ki rate kitni hai

[@volti2829]

Thts very intersting what steel/material did use and what tool i havent any tool like that

[@braveen1000]

Center Lathe.. The mother of the Machines.

[@fredm5245]

I’m keen to add a small finger size knurl to a set of darts. Wondering how easy or could it damage the dart?

[@Teknos78]

So you want to make leather punch for stitching?? Nice

[@Alvinhordista]

How to make knurling on rubber rollers can i know the proper set up of speed and feed to the machine.

[@martin128]

Wondering if i could use that for wood

[@patriciocordova449]

In Australia if we were friends I would call you “Czech Mate”

[@MilanDupal]

Regards around the Globe, dear friend.

[@MadeInGreatBritain]

That may have fallen on deaf ears

[@Toby6440]

Check yourself before you wreck yourself

[@delgrafic]

How many millimeters did you use?

[@FredMiller]

Very nicely done Milan. I am surprised the KZbin police let you get away with the commercial radio music in the background. I do enjoy your videos! Fred

[@BearwoodBrown]

you tube doesnt care its the people who own the copy right who take the revenue if it i s monetized i learned quickly no music in background annoying anyway

[@frantisekzverina473]

Not commercial, it's public radio.

[@SeeHowItGoes]

@@frantisekzverina473 the music in it is the probelem. If a song was played. Then the artist/record company could remove it.

[@FradyKatt]

they will but they will have claim any $$ Made will go to other.

[@superdau]

Does the diameter of the nurling tool have to match the diameter of the work piece? How does it line up exactly again after one rotation?

[@manuelh.6055]

The diameter of the tool does not have to match with the workpiece. And it does not line up since the two wheels have opposite "profile". And because the profile is simple lines it does not matter where they overlap. Hope you did understand my explanation.

[@superdau]

It is simple lines but I don't understand how it would line up in all cases. Let's for arguments sake say, there's a total of 10 lines on the circumference of the nurling tool and it's circumference is exactly 10mm, so each line is 1mm wide. What if the workpiece has a circumference of for example 10.5mm? You can't put an integer number of 1mm lines on that. You end up with 0.5mm "left over".

[@geoffcunningham6823]

superdau the lines are at an angle, so the tool just moves up along the rod enough to get an exact match each rotation. Edit: autocomplete error

[@superdau]

Angled or not doesn't matter. You must have an integer number of lines on the workpiece or else they just won't match up.

[@philipwilliams5429]

my understanding is that with sufficient pressure on the workpiece the knurling tool works into the nearest rational "harmonic" and is stable there; the diameter of the workpiece is usually much larger than the pitch of the knurl, so this harmonic condition is easily satisfied.... it takes more than one revolution to get there, though.

[@LongtowerNyc]

Extremely satisfying to watch.. Thank you.

[@MilanDupal]

Welcome!

[@knex91]

Do the knurlink with a slower rotation and a lot of oil :)

[@felix-ve8jk]

Because that's a better way to knurl

[@wranglertr]

He knurled a lot of part and one of the finished part was done good as pattern. Although he didn't mention about "which diameter" should have learned to make it in lower speed and with more oil. "Why" friend; surface area is greater

[@sametpercin5848]

i agree you

[@nicholaswilson2155]

I've never knurled at that high rpm even on a small diameter like that. Maybe he taps in high gear too..

[@jasonbone5121]

Typically 1/4 speed rotation and speed up the feed rate.

[@akrij4316]

Zdravím mohl bych se zeptat jaký otáčky a posuv jste použil a na jakém průměru to bylo

[@MilanDupal]

Průměr vroubkovanách součástí byl 12mm. Otáčky nejsou rozhodující. Začínám vroubkovat na minimální, až se vzorek po obvodu dobře "zakousne", přidávám plynule podle oka. Posuv rovněž od oka, obdobný jako při točení na čisto.

[@mohsinrasul8450]

Do u need you use oil when knurling?

[@MilanDupal]

Yes, oil is needed.

[@mohsinrasul8450]

@@MilanDupal thanks for the confirmation

[@xl000]

Do the diameter of the knurling tool and the diameter of the target piece have to be a multiple of each other, and does it just work with no assumption on the diameters ? Also I don't understand how it can make a consistent pattern while the lathe is feeding. Does it just work ? Does it align itself with the previous pattern or something ?

[@MilanDupal]

The diameter/girth of work piece and knurling wheel have to be multiple....Yes and No. There are a knurling calculators available for download or online, but I never used them. The friction force while knurling process act the lubricated knurling wheel pattern slide to the corresponded already created groves. Important is to apply enough force during start phase. Yes it does align itself with the previous pattern during horizontal progress. Just take a piece of scrap material and try knurling yourself to get necessary "feeling" and practice!

[@El_Chamuco_Veloz]

How could you do that on a taper work? Like a beavel gear, but instead tooth, make knurl

[@olivvapor4873]

My Czech is fluent now … 😅 What is the minimum lathe size to knurl properly ? … Small diameters say under 15mm …

[@FarmPrepper1]

Be Careful of that live center backing off due to light chuck pressure. Can cause you a good smack from a tool or work item.. It started walking at 3:06. God Bless, stay safe.

[@marwanayache]

Hi. Why you didn't save time and effort and electrolysis it?

[@flugel21]

Please try a much slower spindle speed, but a much faster feed and check the difference!!

[@glintwing]

haha... Was listening to elvis just before clicking on your video! Good job.

[@PacoOtis]

Dude! You obviously know what you are doing but why no narration? You have knowledge and we seek it. You might ponder a different format. Best of luck!

[@MilanDupal]

Joseph, thanks for your message. The video format was "processed" by youtube within download, not taking in mind my intentions... Narration, ...ehm . I am not native English speaking, plus my pronunciation is sure terrible. Additionally subtitles allow me a bit ponder on content. Maybe in near future I'll send my voice to universe. :-)

[@kevinaustin6971]

Nice video Don't worry about your accent (we got our over here in the US too) and anyway it's always nice to hear something a little different.

[@Sgtassburgler]

I find it refreshing to find a channel without someone running their mouth. Do what you want man, don't let these guys pressure you.

[@rajanchhatrola3841]

How can we make knurling for bulk production i.e per day 10,000 pcs?

[@lokchandsantoshkumar7555]

after knurling on the shaft is the shaft size increases or decreases on the knurling area.

[@MilanDupal]

The shaft diameter increase after knurling. (shaft material is pushed out into knurl "pyramids")

[@alanhardman2447]

lok chand santosh kumar - An OD-knurled part gets larger in diameter after knurling.

[@LexsLavrov]

Nice video! Why do you have 6-jaw chuck? I am using 3- and 4- sync jaws chucks.

[@MAJUKARYASENTOSA]

Харитон Круглов usually used for smaller diameter

[@balesmachine]

Is it just me or did the center either move to the right, or the stock move to the left. When you finished, the stock was clearly not engaged in the center any more.

[@MilanDupal]

You are right, the stock was not tighten enought in my chuck.

[@speedcrusader3779]

do you need auto feed to for knurling

[@MilanDupal]

No, you do not need auto feed, but it is yeasier in production.

[@speedcrusader3779]

@@MilanDupal thank you

[@johnhfischeriii]

What pen is that?

[@vladimirgrega4210]

Would it work also on stainless steel tube with wall thickness 0.5mm? Nebo ne?

[@MilanDupal]

Nerez je tvrdý, tenkostěnná trubka se asi při velkém přítlaku zbortí.

[@mdmaksudurrahman]

Thanks for sharing this video....Is there different size of cutter depends on cutter teeth ?

[@MilanDupal]

Yes, there are different pattern wheels available (fine, coarse, lengthwise, diamond,...)

[@AdityasinghBais08]

Isn't it necessary to expose a fresh surface for a knurling operation? i.e. turning -> Knurling

[@davidkeely7855]

I'm a professional precision machinist so let me clarify this, you do not have to have a fresh surface,as long as it is not rusted or has nothing on it that will cause the tool to stop working then you may proceed with knurling. Just be sure to oil your tool and part and have a file card running along the back of the knurl as it is turning to remove any debris from the knurl.

[@AdityasinghBais08]

david keely thankyou.

[@FarmPrepper1]

Loved the Cheq Language Pop up. Hope you are all well there is Eastern Europe. Thanks for the Vid.

[@MilanDupal]

Czech language.

[@FarmPrepper1]

@@MilanDupal Czech!!!. I'm going to read some more. With my glasses on!

[@troywheatland152]

good quality video but 2 errors. when feed ends 4:15 you can see the live centre isn't engage and workpiece bending so tool load not applied to job properly, and get rid of that rag!! rookie error.

[@MilanDupal]

You are right, the chuck was not tight enough while knurling this one piece from series.

[@volti2829]

Is it alumnuim or steel

[@MilanDupal]

Steel

[@ltdan8671]

Is fast speed necessary?

[@MilanDupal]

No, not necessary, but make me happy. :-)

[@ltdan8671]

@@MilanDupal haha, nice.

[@muhammadahsanibrahimnasirm650]

Which material is of oil

[@MilanDupal]

Muhammad Ahsan Ibrahim Karamelahi Any industrial or automotive oil.

[@jumbie4972]

How much for a lathe that size also what's its max Rpm?

[@MilanDupal]

I paid for the lathe itself little over 1000,- EUR. The max rpm are 2200, but from practical experience is much important the lowest rpm and torque.

[@craigrmeyer]

Let me guess: Knurling thin-wall stuff is a bad idea because it makes sharp stress concentrations, right?

[@MilanDupal]

Thin-wall material does not survive heavy knurling force.

[@craigrmeyer]

@@MilanDupal You've done/tried this yourself? Or is it just obvious to you?

[@KarasCyborg]

Can you knurl hardened steel?

[@MilanDupal]

I am afraid using a standard quality pattern wheels is knurling hardened steel not possible. The knurled material surface have to "flow" under the pattern wheel preasure. I suggest harden your steel next to knurling operation.

[@ironclad8181]

can i know what is jaw chuck type of your lathe?

[@MilanDupal]

The chuck is a Czech made TOS_IUG-125-6-1-M2 (www.tossvitavy.com/tosan/index.php/chucks)

[@JaskoBesic66]

Milan, where are you based and do you offer these services?

[@MilanDupal]

Hi Jasko, I am based in Prague, Czech Republic. Yes, I can perform a limited service for you.

[@JaskoBesic66]

@@MilanDupal Hi Milan, What if we want to produce in scale, how big is your capacity? :)

[@MrAlexg91]

Aside from informative, this was also very relaxing to watch

[@savedbygodsgrace.9058]

Nicely done! I use to do this on surgical instruments. .we knurled titanium . Concerns with Chuck speed though? ..

[@MilanDupal]

Thanks for message. There is no issue concerning speed, it just works well.

[@steve20664]

Spindle speed too fast.

[@raymondjack4634]

Elvis Presley suspicious mind. One of my favorite songs.

[@MilanDupal]

Honestly, I do not much care of transmitted songs, just love some chattering from radio to complete my machinery noise. :-)

[@par4par72]

At first I was saying..toooo fast !!! Then I was like....just waiting for that rag to catch something spinning. Dad used to say.."respect the machine because it has no prospect for you"!!!

[@MrKkdkk]

What were you making, mister?

[@MilanDupal]

I was making handles for punch tools.

[@PrinzEugen7ss]

Good job , but best the close-up and photography congratulations.... cheers from Chile

[@vinod60kar15]

Knurlig tyapes ket ne types ka hota hai

[@officaldogukan822schannel2]

what is the music at the end ?

[@MilanDupal]

Oskar Schuster Sneeuwland freemusicarchive.org/music/Oskar_Schuster/Sneeuwland/Sneeuwland_1553

[@officaldogukan822schannel2]

thanks, really good music taste btw.

[@gussuk11]

I have never understood how the spacing of the knurling tool doesn't match the diameter of the shaft why doesn't the grid created overwrite it's self making a mess of the knurled pattern. Say the spaces between the lines on the tool is .5mm and the diameter of the shaft can't be equally divided into .5mm divisions? not to mention the diameter of the shaft gets smaller the deeper the impression becomes.

[@MilanDupal]

The knurling force act the wheel pattern slide to already created growes. BTW, the diameter is during the process of creating groves changing.

[@gussuk11]

@@MilanDupal thanks so the tool meshes into the previous grooves as it meets the previous pattern. got it.

[@nazuaaureliaprayoga]

is that a diapper?

[@frankstrawnation]

A paper towel.

[@fpm1979]

What’s the name of that piano piece at the end of the video?

[@MilanDupal]

Felix Müller freemusicarchive.org/music/Oskar_Schuster/Sneeuwland/Sneeuwland_1553

[@sagarsagu8031]

Can we do knurling with very high speed (rpm)

[@BigAsklin]

Sagar Sagu I thought if was going too fast I go maybe 200 rpm

[@republikpropaganda2319]

To vypada dobre

[@Abohmedjt]

you are amazing

[@seantinman3130]

Hi may i know the bran of your lathe and how much can you sent me a link or any market.

[@MilanDupal]

The lathe is a Optimum (Quantum) D210 x 400. Look at stuermer-maschinen.de for local dealer.

[@InobuZ]

I needed to use a larger tool the other day......I took the original tool post and cut the bottom portion of the base. It allows the tool to fit and the other side is intact.

[@camberlubos3995]

Pekná práca Milan. Nevieš odporučiť nejaké knihy o sústružení, rad by som sa niečo naučil. Vďaka a veľa úspechov.

[@diecksl]

Interesting. Always wanted to know how its done. Now somebody has to show a video of how the knurling tool is made :-)

[@MilanDupal]

I do suppose the knurling tool (wheels) are made similar way from master pattern wheel, than hardened.

[@valy5684]

Have a look at Clickspring's channel. He does some crazy high precision machining and he made his own knurling wheels.

[@oscarpisstorikiller8779]

Lejf Diecks You are very young looking. You are very clever for your age. You have a big future in front of you.. I wish i was as smart as you at such a young age. Your parents must be very proud of you. You are amazing child. All the best in years to come. You are a true ingenious at such a young age. I showed your picture to my wife and son. They are very excited as well. I cant believe someone so young is interested in this field. I had tears in my eyes when i saw how young you are

[@oscarpisstorikiller8779]

Toolman329 thank you so much for your expert advice.. Have a lovely day

[@numbr6]

How is the master patten knurling tool made? It looks like to me like two spirals in opposing left/right hand directions, sort of like right/left hand drill bits. I know little about machining parts, so this is just a guess.

[@ieyazzu9297]

Machinery is fascinating.

[@joepsalman9160]

Looks amazing man! Nice video

[@MilanDupal]

Thanks!

[@Equismaximus]

1. The spindle speed for the Center Drill is WAY, WAY to fast if I am judging your speed from sound. 2. The spindle speed for the knurling tool is WAY, WAY, WAY too fast. 3. Your knurl depth is nowhere deep enough. You do not have diamond shape to your knurl so it is substandard. 4. You do know you can take multiple passes with a knurling tool don't you. 5. You need to put some oil on that part do keep the metal flaking from getting embedder in the knurl. 6. Blowing off the part with air will reduce the chance of grinding metal back into the knurl. I usually have oil in one hand and air in the other constantly keeping the tool clean of debris. The cutting speed of the Center Drill should be roughly 4X the cutting speed of the CRS Steel you are using divided by the diameter of the Center Drill in this case. That would be (4x110) / (.125) or approx.. 3,000 depending on coolant which in your case is a few drops of oil. Your speed is up around 5,000 rpm which is a good way to burn up tools. I usually turn a little slower because the body of the center drill tends to chatter at higher speeds. Too slow and you will break the pilot off. Looks like you are using a#3 or #4 center drill so let's say you are using a #4 to be safe, which would bring the speed down as in the example above. If you are not using a coolant flood then your spindle speed would be decreased quite a bit to be safe. Without seeing your lathe it sounded like your spindle speed was about 5,000 rpm which is way too fast. For knurling you should use a Surface Feet Speed of about 4x110 / Diameter of the Work or (4X110/.5) assuming your part is 1/2" in diameter which yields about 220 rpm. Your knurling speed is ridiculously too fast. You are traversing the part much to slowly you should be across that part in about 20 seconds or less. The longer you stay in one place the greater chance of imbedding metal shards into the finished knurl which makes is useless and ugly. If you take a second pass you should clean the knurl with a wire brush, blow it clean, and then oil and take a second pass. The more oil the better as it will flush out the chaff from the knurl. If you don't do this the knurling tool wheels will clog up with metal. If you did what you are doing on brass you would end up with a piece of junk. On softer metals everything gets much more difficult. The brass flakes off and imbeds in the metal ten times more. Getting a good clean knurl takes a lot of experience. Longer parts are harder to do because the knurling tool tends to push the part away in the middle of the cut on smaller diameters. You have to resort to a clamp type tool in that case. One more thing your knurling tool should have a slight angle on it so as to not present a sharp edge of the knurl rollers to the direction of cut. Perhaps around 5 degrees or less. Maximus has spoken.

[@petermoss5341]

I am SO GLAD you were not my dad. Great advice for sure though.

[@holton345]

Nice job, sir! Please post more like this. Thanks!

[@MilanDupal]

Thank you! New video already launched.

[@Fab2Mc]

Super 👍🎉

[@crouchingwombathiddenquoll5641]

Thank you.... always wondered how that was done.

[@MilanDupal]

Welcome!

[@jirgen6247]

ej a jak se tomu říká v češtině?

[@MilanDupal]

Vroubkování. Vroubkovat.

[@jirgen6247]

dik

[@aaleshx]

Rádlování

[@x259petr]

rýhování

[@prashantsen3719]

🙌🙌🙌🙌 good job sir ji

[@MilanDupal]

prashant sen Thanks!

[@jamescole3152]

I watched a video of a guy that had a list of diameters that worked with his knurl master scissors tool.

[@بشرعادي]

تدعى هذه....العمليه.... ب الكزكزه....وهي عمليه تخشين السطوح الناعمه.... لتسهل عملية اللمس.... في البداية....عمل تثقيب....حتى يسند قطعة العمل....بواسطة...(الغراب المتحرك)... ثم اسندها.... ووضع عليها سائل....تبريد....احياناً يكون زيت....ام مستحلب مائي.... ثم يبدء القلم.... المدعى... بقلم الكزكزه....بتخشين السطوح.... كل هذه العمليه.... تجري على ماكنة الخراطه.... محدثكم.....اختصاص....قسم ميكانيك مرحلة ثانيه🌹

[@steve20664]

Speed looks a bit fast, but those old tools are pretty good. 👍😎

[@darekdarek7753]

Taki duży obrót bez chłodzenia? ???

[@MilanDupal]

Cooling not necessary, the small amount of heat absorbed in part.

[@Cuetips1000]

3:30 Watch closely: Live center does not support anymore.

[@MilanDupal]

I know, the workpiece was not tighten enough in chuck.

[@MrManniG]

Knurling sounds so cute for doing metalwörk, in german it is called "rändeln"

[@MilanDupal]

In Czech is called "drážkování" :-)

[@phrodendekia]

In spanish its called 'hacerle rayitas o qué se yo' Not really

[@MF175mp]

In Finnish it's "pyällys"

[@Scarz1991]

Elvis Presley! Nice! 🤘🏻🤘🏻🤘🏻🤘🏻

[@yarredthomsson3945]

Si říkám, že to natáčel další Amík a tam Český Rozhlas :DDD

[@MilanDupal]

Američan z Vysočan :-)

[@anton6643]

Нихуя не понятно

[@vitfirt4435]

Taky jsem si říkal. Jen se blbě zeptám, ten posuv musí být automatický nebo můžu posouvat ručně?

[@wiliam5074]

@@vitfirt4435 Kľudne aj ručne.

[@oskar22fridolin17]

Usually you lubricate and cool the tool and part -

[@Fab2Mc]

Super 👍👍🔥

[@mareknovotny8861]

Já to mám udělat bez automatického posuvu

[@Majk_L]

Růčo kolečkem

[@Digitalsurfer265]

I still have no idea how it works

[@williamhuang5329]

Hanzhen harmonic drive gear , strain wave reducer, robot arm gear , over 30 years experience

[@FungiGuy195]

I just came for the music and Czech lessons

[@donaldmack7213]

To quote the old Bandstand show from the 50’s and 60’s outof Phildelphia , PA about the music. Good beat , easy to dance to. I give it a 10!

[@scottvincent7666]

Knurling tool is a Armstrong brand. A good one.

[@Kiisu8888]

Looks like you're making leather punches. Good job looks nice.

[@MilanDupal]

Exactly, leather punches.

[@stevek5416]

You are lucky you got a good knurl pattern, because your work is being forced into the chuck by the tool. At the end, the live center wasn't even engaged. You might get better results by knurling from the head to the tailstock - the tool will try to push the work into the tailstock.

[@grahambungate7009]

I always thought that you had to have knurling tool wheels equal height to work. If not one wheel makes a deeper impression. Eg if bottom wheel is so low it misses work then only top wheel is doing the knurling. Just sayin

[@MilanDupal]

Theory vs reality...

[@thomasmica2856]

Прикольный станочек )

[@donnahansen1204]

Mill the tool holder to accept the size of the tool

[@MilanDupal]

Good idea, will do!

[@USMC_BABE38]

I've never done this before but I've watched my dad do this

[@MilanDupal]

It's time for your try!

[@machinemafia2616]

I have performed this in cnc turning

[@jamescole3152]

Nice. Now I know I can do this on a small lathe.

[@gustavoedgardorichard3735]

very good ....thanks......from Cordoba ..Rep.Argentina

[@MilanDupal]

Thanks, regards to Argentina!

[@danielsousariassouzadias9788]

O recartilhado está ok quando o mesmo está uma pirâmide perfeita ..