Making Worm Gears With Taps - BUSTED

[@Dogfather66227]

It’s interesting to me that some of the most authoritative and widely-used mechanical engineering and manufacturing engineering textbooks provide some theory regarding worm gears but little about how they can be generated other than to possibly reference the hobbing process. (An exception is a textbook by author Mott). Even machining textbooks used in trade schools that I have seen appear light on the subject. So it is especially good to see references like the Ivan Law book, for example, provide practical solutions to cutting gears in the home shop setting. Thanks for posting this particular method and its limitations. Although I am not likely to rush out this afternoon and and use it to cut some metal (my lathe supports module threads), I appreciate the time and effort taken to shine some additional light on this method. It was well worth watching. Hope the hand continues to do well.

[@ThePottingShedWorkshop]

I've never tried using a tap to cut a worm wheel, but I did have one application which demanded a custom hob, so I understand all youre explaining. In my case, my chinesium bandsaw ate its brass (!) worm wheel, mod 2, so I ended up making the hob, gashing the blank (at 0 deg) and free hobbing the wheel. Its still working 3 years on, so I cant have done that bad a job!

[@jeffarmstrong1308]

Great video - again! As a Clickspring follower I have been putting off making up a proper module gear cutter. I have a project that is going to require two half gears and I had been dithering about using a tap for the hobbing. Your video has convinced that would have been a waste of time and I've decided to bite the bullet.

[@Sven_Hein]

The pointy teeth are quite helpful for making feed gears for wires or for filament in a 3d printer. Usually you’d use an M3 tap though.

[@davidelang]

I'd say that one advantage of using a tap to create the worm gear is that you can then use a standard threaded rod, bolt, or tapped rod to drive it instead of having to cut a custom piece. I agree that it may not be as good in theory, but the bigger question is if it's good enough in practice.

[@boots7859]

Good point.

[@a-k-jun-1]

Gp all put and use an acme thread tap. Puts less stress on the shaft in my opinion due to the squarish threads not pushing apart like regular 60° threads do. Just my OCD talking here and not any recommendations.

[@Vikingwerk]

Yeah, all this sounds about right. A friend of mine and I did about 8-12 trial and error attempts at using a tap to make a gear for the apron of a lathe he got for free; we finally got it, but like you said, it’s not easy, and not perfect in the end even when it works.

[@gallaghergreen2053]

This was great. I am thinking of making a worm gear this way, but all I need it to do is essentially raise and lower a small curtain, so very low use and stress.

[@howder1951]

Definitely "good to know" info for when that gear goes in the band saw or whatever. Enjoyed sharing this time with you and perhaps I will recall when I need worm. Thanks and cheers!

[@martinsmith251]

Makes his own gears, talks through the pressure angles and trade-offs between angle and efficiency, and then says “I’m no gear-ologist”. Maybe not, but I think you’re close!

[@masondegaulle5731]

He's not a gear-ologist, he's a worm-drividian

[@thomasthecrunkengine3512]

Seeing the artisan notification and immediately clicking it makes me happy

[@jackdawg4579]

Cheers for that, i had no idea how module gears were calculated.!

[@AnWe79]

We used to make the "hobbed bolt" for 3D printers using this method. Not easy to freehand with a jury-rigged jig, but it worked okish. M3 or M4 taps were used IIRC.

[@docshotshopandforge]

Use a spiral fluted tap, better tooth engagement and less risk of it not advancing fully for the next tooth.

[@howardosborne8647]

I think exactly the same thing every time I see someone post a video of the free hobbing method with a thread tap....the spiral flute tap surely has to be the preferred option for this process.

[@docshotshopandforge]

@@howardosborne8647 I made a few large worm wheels back in the early 2000’s for telescope drives that way, first one was with a regular tap after that all with spiral fluted taps. Works way better. Really no comparison

[@bradthayer6782]

Wow, I think I now have a masters in tne topic. Nice job!

[@machinewrangler4682]

It’s a great cheat to make a worm wheel, yeah although it not the best geometry it’s quick and easy. I did try this technique once and was impressed at how it turned out. I opted for a more challenging blank by using 4140 and an M24 spiral tap. (I have a feeling the spiral tap made it easier) I did hog out the concave. And like knurling you have to plunge in quite firm to get the start perfected. First attempt came out full form and really nice.

[@RobertBrown-lf8yq]

I like to watch your ‘craft’ 👍 You are one very inventive dude 👏👏 Regards Robert ( Sydney)

[@PaleoWithFries]

You might say that gear profile... grinds your gears 😎

[@rallymax2]

Great research. I hope your finger is getting better.

[@MCsCreations]

Really interesting stuff indeed! Thanks, dude! 😊 Stay safe there with your family! 🖖😊

[@Cjs-n2n]

They make nice rope knurls when made out of silver steel and hardened

[@laurawerner]

Good video! One quibble, though - In those video thumbnails you showed at the beginning, I noticed some from @AndysMachines. His gear videos aren't actually in the "Make worm years with a tap" rubbish category you were criticizing, and they're worth a watch if you haven't seen them already. Andy built a gear hobbing attachment for his mill. He puts a gear hob in the spindle, and the attachment rotates the gear blank at the correct speed to make perfectly hobbed gears. There's electronics involved: he uses a rotary encoder and a servo or stepper motor, plus some code that he's made available, to synch up the rotation. Very clever. I want to build one someday.

[@smashyrashy]

Blah blah blah

[@SuicideNeil]

@@smashyrashy Odd response- I'm subscribed to AndysMachines too and that video is indeed not in the same catergory as the other 'DIY hacks' rubbish. You might want to actually watch the video in question before dismissing legitimate comments.

[@jackfromthe60s]

@@smashyrashy jerk

[@zorbakaput8537]

That is not good form on your part

[@jackfromthe60s]

@@smashyrashy I called you j*rk earlier and it got deleted sadly. Try again. J.e.r-k.

[@ThantiK]

The tap method is how some of the early guys in 3D printing made drive gears for filament. The fact that the teeth were shallow and sharp was actually a benefit when you couldn't afford the proper tooling.

[@Königskind-c5o]

I successfully made one or two M10 worm gearboxes with a standard tap on my mini lathe. I had no use for it as I just wanted to see, if it was possible, and it does work as a 20ish :1 gearbox. If you are sceptical about the tooth profile and pa, maybe a trapezoidal thread tap would be better

[@JanBinnendijk]

Good Comment on the Trapezoidal or Acme threads.. better pressure angle. but if you need to make a Hob on the Lathe.. , do some calculations and get the right pitch to match a Modul..

[@ED_T]

The fact that there is no standard in industry for this kind of gear profile should tell us all there is to know about this method. It does look like a fun experiment though

[@BillDavies-ej6ye]

This method isn't used by industry, and it doesn't produce pairs of gears that can mesh. But if you wanted a gear that can run against studding or all-thread acting as a rack, this works. I used it in 1969 for the focussing of a homemade photographic enlarger, and it worked fine. It will also work as a worm and wheel for simple hobby or toy applications. As mentioned, the pressure angle is somewhat greater than standard gears, which increases the force pushing the worm and wheel apart, reducing the torque that can be transmitted.

[@roboman2444]

I wonder if its possible to make something that uses the leadscrew of the lathe to automatically turn the gear blank at the right speed relative to the hobbing cutter. May solve that problem of not having enough "bite" for this tap method, but it would probably also help with precision when "doing it right" with all the proper cutters and profiles. I would suspect that setup would utilize the leadscrew as a worm drive itself, turning a small gear that then drives a vertical shaft that the blank is attached to. You may need some UV/CV joints or other trickery to allow the blank to be moved in and out, though, but these are pretty common and can be found in lots of places, including hobby R/C cars.

[@jr764]

I feel like an ACME tap would solve a lot of the problems you brought up

[@cooperised]

Those things are expensive, though.

[@JB-ol4vz]

W ell explained man. Thanks.

[@ryana2652]

I had the idea of doing this 20 years ago. After doing the maths, I realised it's a silly idea. It's JUST practical enough for the hobby machinist. Your application seems to be in that category. For a proper gear,ect. You need both driven blank and a driven tool. And not a tap 😅

[@roboman2444]

What about using off-the-shelf straight cut spur gears as the gear? I assume that as long as the ratio of the screw diameter to the gear thickness is high, then it won't be "too bad". Would be interesting to see comparisons of all these gears. Wear profiles after spinning a load for 24 hours, forces applied to the shafts, "efficiency" measurements, and finally max torque before things break. I assume in many cases, some of the less "perfect" gear setups may be worth it, since they are so much easier to make.

[@gangleweed]

By my guestimation a rack with 29 deg teeth will mesh with a standard involute gear ........for a worm drive, as long as the worm is set at the helix angle to the gear it will mesh and drive freely...... but if you need the worm to be at right angles to the gear, as in a normal worm drive gearbox, then you should cut the involute gear teeth at an angle too.......there is no need to make the worm wheel with a hollow profile..... a straight cut across the gear blank will work fine.

[@fuzzy1dk]

it is probably more suited for things like a gear for setting the angle of something with a control knob, than transferring power

[@RectalRooter]

In 1903, Wilm discovered that an aluminum alloy with 4% copper would harden if left at room temperature after quenching. Would you be willing to mix some up and machine it in it's soft state and allow it to harden ? I'm curious if it would work out. Soft easy to machine metal that gets hard without needing tempering.

[@sandarelliott5319]

Hey mate, well done with all your research and how you explained it, i think you done it well. i just wanted to say that you're focusing too much on Mod or D.P, the pitch is the pitch and you just make it to suit as youre making the pair (typically) like if youre making a M10x1.5 worm wheel you work off that (1.5mm). Obviously there is no guessing games and everything has a formula; O.D of gear, pitch diameter, throat diameter, throat radius and so on. so this means theres no real stressing over dimensions, you can even make the O.D of the worm gear smaller (Truncation) or larger and it wont matter as long as its not too much. Ive cut a worm wheel where the O.D was the Pitch Diameter so it was missing 3 whole addendums off the O.D. I cut gears and worm wheels for a living so this is just my two cents. I work by axial pitch in inches, everything is based off that, O.D of worm, Number of teeth in the worm wheel and the centre distance whether it be standard or modified. ill admit i don't do stuff that tiny very often so mileage may vary to my advice. In my opinion, stuff that tiny doesnt really matter for contact pattern or efficiency, as long as its got some sort of tooth it will transmit torque. like you said, worm reduction isnt very efficient but it does work very well. Here is an example of a 40:1 M10x1.5 from my spread sheet. (All sizes in Inches) imgur.com/a/BuDFLru

[@artisanmakes]

Maybe I did, but that might have been a bit of fall out from the fact that I was pretty disappointed/annoyed that none of the viral videos made no attempt to explain that fact. If you look at the comments in those videos there are a lot of people asking how to calculate the worm diameter and its never addressed. I think I wanted to drive the point home here. Plus I did have to scratch my head for a bit to figure out how to exactly come up with the formulas. Also for what its worth, I don't like the idea of a gears diameter being circumference driven because it usually results in a weird diameter which you have to hit. Like 25.464mm diameter (which is what you measure for) for a 80mm circumference. I just think its more intuitive and straight forward to turn things to whole numbers, which most module gears are. That was more my angle for getting caught up on the pitch/module debate.

[@sandarelliott5319]

@artisanmakes yep you're right, I forgot it was free hobbing. Im just used to setting the number of teeth on the machine lol. Great vid though.

[@mr.picklesworth]

I'm curious what cad program you use? How do you like it?

[@justinst.4592]

It looks like solidworks. Works well, but it’s expensive

[@Dogfather66227]

@@justinst.4592 Correct me if I'm wrong but I believe that Solidworks is available to "makers" or individuals on sort of the same basis as the no-cost Fusion 360.

[@vx-iidu]

@@justinst.4592 🏴‍☠

[@seabreezecoffeeroasters7994]

Yep Solidworks, unless you own a legacy/older perpetual license it is to expensive for the average Home user. All of the 'free' software comes with baggage and only beleive about 1/2 of what some random KZbin head tells you is AWESOME. Freecad is improving but still kind of Beta in a lot of areas, Blender 'is not and never will be CAD', Fusion 360 'free' has some limitations so go in eyes open (it is what I use and pay for by choice) Any of the other 'online' or 'free' ones have publish or else clauses or are not well featured. Not a complete list but a few to look at.

[@nommy8599]

I like that you did this, your points all made sense except the complaint about removing pi from the equation. I don't fully understand this but I recall you describing the difference as one method using radius and the other diameter. As diameter is 2Pi*r it seems trivial for Pi to be in the equation, and have it based on radius. Let me know what I'm not getting here.

[@BillDavies-ej6ye]

Pi is used to ensure that nominal inch or metric dimensions exist between the centre distances of pairs of meshed gears. Diametral Pitch (DP) is the number of teeth divided by the pitch circle diameter (PCD) in inches. A 16 tooth gear of 1 inch PCD is a 16 DP gear. Module is the PCD (in mm) divided by the number of teeth. Notice that the formulae either have the number of teeth on the top or the bottom. Thus, like imperial & US threads have nominal numbers of threads per inch of thread length, metric threads use the pitch, or distance in mm between adjacent thread forms, not over a specified distance.

[@artisanmakes]

Sorry if I wasn’t clear on that. Because module/gear size (the tooth spacing) is based on Pi. It means that the gear pitch diameter is simply number of teeth x module. So I work with module 1, I need a 40 tooth gear and the pitch diameter for the gear blank is 40mm. No need to work with pi. The gear blank calculations are much simpler since parts are usually measured on the lathe using their diameter and usually you’ll end up with while numbers. This is much easier than needing a gear blank with a circumference of 40mm since the diameter would need to be 12.732mm which is a less intuitive measurement to make.

[@nommy8599]

@@artisanmakes makes sense cheers

[@ThantiK]

It wasn't Radius and Diameter, it was Circumference - so the perimeter of the circle was driving the calculation, instead of the distance between edges or center.

[@nommy8599]

@@ThantiK yeah I put the wrong word, good catch

[@ydonl]

I think some of the motivation to use a tap might be a more modern cultural norm that “easier Is always better.” The ultimate “easy” is just buy one rather than make it, but there is sometimes a quest for the easiest method, rather than the one that produces the best results. I prefer quality, and the satisfaction of a job done well and properly! Personal standards.

[@danielmclellan7762]

Not once did i hear the word "involute" , which makes me wonder

[@BillDavies-ej6ye]

It will produce an involute, as the process is effectively the same as for normal hobbing of wormwheels. But this setup doesn't allow the tap to pass through the gear blank vertically, so cannot produce a spur gear. If this could be arranged, the tap should be set at the helix angle of the thread, but the gears produced would be incompatible with standard gears, though would mesh with others made the same way, with similar or different numbers of teeth.

[@danielmclellan7762]

@@BillDavies-ej6ye he's producing the involute as a casual artifact of his process rather than by intent.

[@BillDavies-ej6ye]

@@danielmclellan7762 If you mean causal, I agree, Daniel. Whether intentional or not, the form will be an involute.

[@danielmclellan7762]

@@BillDavies-ej6ye causal indeed

[@zorinho20]

Any commercial small worm gears that I have are acme threaded,so I was thinking to get acme tap and try with it.

[@artisanmakes]

A 14.5 PA angle gear very close in profile to a ACME thread profile, biggest difference is the pitch

[@pettere8429]

I am fairly sure it is a hand plane, not a hand planer (I do not like the idea of getting my hand planed...).

[@cheztaylor8]

Yes, a hand planer smoothes the wood after the hand sawer. ;-)

[@mylittleworkshop7219]

Um actually 🤓

[@jackpijjin4088]

It's like calling a hammer a 'nailer' or 'nail hitter.'

[@LeePorte]

​@@jackpijjin4088 you mean a thumb finder.

[@artisanmakes]

It can do both

[@jackdawg4579]

interesting, i wonder if it would be worthwhile someone making a tap type tool but formed so that it will cut normal modulus work gears using a lathe.

[@Yoye01]

I like to ask your 4 jaw chuck is bolt to the lathe with 3 bolt or four? I have lathe and i need independent 4 jaw my late chuck i bolt with 3 bolt let me know what model of you 4 jaw chuck is and where you ordered from thanks

[@artisanmakes]

I made a backplate for it using some 130mm diam. 1045 steel. I am sure you can buy them

[@artisanmakes]

skip 16 minutes in kzbin.info/www/bejne/qIXMpmyFnp1oisU

[@JasonAWilliams-IS]

I understood pretty much none of that lol Something about gears?

[@Sarcasmarkus]

I'd guess those who are using taps to hob gears are probably trying to get er' done without mathing and not going for perfection.

[@Joe-xq3zu]

Which is fine, sometimes that is all you need, but people should be aware that you Will be getting less than optimal results from this kind of 'fast and dirty' method and adjust expectations accordingly.

[@MarcusLindblomSonestedt78]

The gears not having the involute shape needed to "roll" across each other seems the biggest downside for me.

[@BillDavies-ej6ye]

Well, they will generate involutes, but they won't be spur gears that can mesh together.

[@MarcusLindblomSonestedt78]

@@BillDavies-ej6ye ah right. Had to think a bit and read your other answers here. But if you drive it with a threaded rod, that part would be cause of the missing involuteness.

[@ILSCDF]

Involute gears don't roll, they slide on each other's profile except at the pitch diameter

[@BillDavies-ej6ye]

@@MarcusLindblomSonestedt78 I'm not sure what you mean. The involute is formed as the part is cut. The threaded rod becomes the rack, with straight sided teeth. If you take the view that the rack is a gear of infinite radius, then the straight sides are also an involute.

[@tims6870]

Now I may be wrong, and by no means am I putting the man down, I been watching this channel for years and I enjoy his content alot and take my hat off to the man for how he does what he does, but... from what I think i understand of gears and the design of gears, the comment about the module x pi being the pitch of a gear which is true of module gears and the example of a m10 x 1.5 thread tap using the circumference and not the diameter as a module pitch uses made me do a double take, because if you divide the circumference by pi, then you get the diameter, and pitch is simply the spacing from one tooth to the same point on the next tooth, which means they are actually both the same calculation in a round about way, just expressed differently. One multiplies the module x pi and gives a diameter for the gear blank and the other requires the pitch to be multiplied by the number of teeth to give the circumference, which is a product of pi and the diameter. Now gear theory is a big subject and I commend him for taking on this topic and trying to add to the information available for hobbyists, one thing I will add which is a major draw back of a thread tap being used as a hob, is the natural tendency for a hob cutter to provide a true involute profile due to the continuous cutting of the tooth through the range of contact at differing angles that continuously change as the gear blank makes contact with the hob. Involute gears have a matching involute toothform, meaning a good mesh is achieved, a metric thread doesn't, so the gear profile won't match the thread profile at all even though the spacing or pitch is the same, and backlash in this particular method would be quite noticeable I'd imagine, especially once everything had bedded in. The power transmission would also be intermittent as the pressure angle would be inconsistent as the contact of the teeth was made and the gears would whip and stutter as they came under load and out of load etc, meaning a continuous velocity wouldn't be achieved. There is a term for this but I can't remember it sorry. I do however think a better example of a thread tap worm gear could be created using a 12 x 1.75 spiral flute tap or a 14 x 2 spiral flute and grooving it to the radius of the tap size to ensure a more complete tooth form is established, even if you cut 75 % to depth then flipped it upside down to cut to full depth (I noticed his gear had deeper gashing on the top than bottom). The spiral flutes should allow the gear to advance better as the profile is formed and should provide a cleaner cut. Same will be true for the home made hobs as well though, it's a similar theory behind a helical gear compared to the straight cut design for spur gears. It's definitely not a commercial solution, but if done with a bit of planning and careful selection of the tap used as the hob, a simple worm gear can be produced that will enable people who don't have the means to single point thread worms and hobs etc to create parts to facilitate the transfer of motion or a transmission of torque or rotation even if inefficient by adapting threads from bolts in the place of a machined worm, which is pretty cool.

[@artisanmakes]

Maybe I did spend a bit of time on the pitch vs module section, but that might have been a bit of fall out from the fact that I was pretty disappointed/annoyed that none of the viral videos made no attempt to explain that fact. If you look at the comments in those videos there are a lot of people asking how to calculate the worm diameter and its never addressed. Yes circumference and diameter are just separated by pi, so they're not that different but I still don't like the idea of gears being circumference driven because it usually results in a weird diameter which you have to hit. Like 25.464mm diameter (which is what you measure for) for a 80mm circumference. I just think its more intuitive and straight forward to turn things to whole numbers, which most module gears are.

[@gaurdein]

yay

[@pauljcampbell2997]

Just some advice. Using a battery charger to power that DC motor is not the best idea. They're usually not filtered or regulated. Better to use a proper regulated 12 volt DC power supply with sufficient amps to handle that motor.

[@boots7859]

Battery chargers are usually filtered to ~14v +/- a small amount. Not gonna hurt most/all 12v motors. You are probably thinking of the older style wall-warts

[@keithammleter3824]

@@boots7859 By "filtering" he doesn't mean control over voltage. Battery chargers don't put out pure DC, they put out pulsating DC - the result of not having any means to store charge between pulses, the storage is known as filtering. Powering a small DC motor with pulsating DC from a battery charger will cause excessive heating and may cause the field magnets to loose their magnetism.

[@seabreezecoffeeroasters7994]

@@keithammleter3824 Going back into the dim dark past low frequency PWM got used on early Speed Controllers for electric flight and I never saw any magnets have issues on the 360-600 sized brushed motors we used to suffer with. Most old school chargers like what was shown run some sort of Capacitor filter and a 1/2 or full Bridge rectifier so they are cleanish and are way better than some of the junk end DC-DC PSU's out there for running small Motors.

[@keithammleter3824]

@@seabreezecoffeeroasters7994 I didn't say WILL, I said MAY. Pulsating DC, eg from battery chargers or SCR speed control is a well known problem with DC motors using alnico field magnets. This is because a pulsating (unfiltered) causes an alternating flux to flow through the field magnetic circuit. That's how you demagnetise anything - give it an AC field. Further, a DC motor runs at the speed at which its back-EMF almost equals the supply voltage - back -EMF is the voltage produced by the motor acting as a generator. When fed from an unfiltered supply such as a battery charger, the motor must run at a speed at which its back-EMF neary equals the supply peaks. For most of the time between peaks the charger diodes block and the motor coasts. This means the motor is forced to draw all the current it needs in short bursts, so it runs inefficiently and gets much hotter. DC motors using ferrite field magnets are much immune to the demagnetisation problem, but still suffer from overheating. Note that it is the armature windings that get hot, so you won't necessarily feel it in the casing. Ordinary battery chargers intended for car batteries never had and still don't have filter capacitors, because for that application the capacitors simply aren't needed. Som chargers may have small capacitors to suppress radio interference due to the diodes suddenly turning off, and to protect the diodes from switching transients, but this is not common and the capacitors used are way too small to do any filtering.

[@MrReichennek]

The top video in that youtube feed is a form tap, it does not cut it deforms metal, i am skeptical as all hell it even worked in the video.

[@jerrysanchez5453]

Why not use a tap? Cause it's a gear

[@chrishill6276]

Yeah it’s a plane. A planer is electric

[@JoyfulJapaneseMaples-us7on]

I used to like these videos, but this was just tuning in to a math lecture. What's a worm gear? Why I it used? Did we see an example of whatever he made vs a tap? What was all the talk about pressure angles and something pushing against something else and diameter vs circumference and his lathe doesn't cut modules (or whatever tgat means.... I thought lathes cut standard or metric but we're talking modules now.... huh????) Very disappointing as this was CLEARLY an video made simply for ego and an opportunity to show us how smart he is. Nothing a "commoner" can relate to and nothing like his other videos. I can a book too pal

[@zorbakaput8537]

Comprehension issues?

[@ourtube4266]

The man is free to make videos on whatever topic he likes. Gears are a very important part of machinery and it’s not his fault that you’re not open to learning. P.S. Module is the relationship between gear diameter and teeth. It has nothing to do with standard or metric threading

[@keithammleter3824]

Artisan didn't make this to entertain the general public. If you want brain-in-neutral entertainment, go watch the pulp on TV. This video is intended to inform those who are into hobby machining and are thinking of moving into making worm gears, and need to know the pros and cons of a method some hobbyists use. He does that quite well. Don't knock things you cannot understand. There are videos on brain surgery on KZbin. Only doctors can really understand them - because that is the intended audience.

[@JoyfulJapaneseMaples-us7on]

@keithammleter3824 What, in my original comment, led you to believe that this video was the first Artisan video that I've seen? I've subscribed to his channel for 3 years. I've been a real-lifey machinist for 4 years. Like.... it's how I pay my bills. Ya dig?

[@keithammleter3824]

@@JoyfulJapaneseMaples-us7on : You a machinist? with what you wrote, indicating you did not understand the subject? Yeah, sure fella - and I am Albert Einstein. I never said you hadn't watched any of Artisan's videos before - looks like you have comprehension issues as Zorbakaput said. Artisan has done something useful - pointed out that a method promoted in many KZbin videos has some disadvantages.