Page 1 of 2 12 LastLast
Results 1 to 35 of 38

Thread: Hypoid saw question

  1. #1
    Join Date
    Feb 2005
    Location
    43*39'27"N; 70*15'35"W
    Posts
    2,989

    Default Hypoid saw question

    Wit all the talk of hypoid saws in recent, uh, boisterous threads I have been wondering...

    What makes they hypoid saws so much preferred for things like long gentle curves, etc.? Is it the left hand blade or the low center of gravity or the fact that the handle is so far to the rear of the blade?

    Please forgive my ignorance- I don't have a hypoid saw and don't do much dimensional lumber framing work. Also, what makes a hypoid saw so much better for construction than say for example my left hand PC 423 MAG?

    Last but not least, what is the current preferred make/model? Still the Skil 77?
    Bill R

    There was supposed to be an earth shattering KABOOM!

  2. #2
    Join Date
    Apr 2003
    Location
    Dallas and points north
    Posts
    7,636

    Default Re: Hypoid saw question

    The Makita is a hypoid saw, most of the rest are wormdrive saws. Makita says their hypoid gear system is better and requires less maintenance.

    The left blade worm drive or hypoid saws have lots of power and obviously make it very easy to see the blade when cutting along a line. Worm drive and hypoid saws have the blade spinining on a different plane than the motor, which has a "gyro" effect.. which results in a very easy to control saw. You can cut along a line once the saw is running with one hand... and its amazing how easy it is to stay right beside the line.

    Sidewinder circular saws (regular skill saws) can "self steer" with carbide blades so to follow a line you have to keep a firmer grip on the saw... plus you can't see the damn blade worth a hoot for cutting along a line.

    RodB

  3. #3
    Join Date
    Jan 2000
    Location
    Portland, Maine
    Posts
    18,199

    Default Re: Hypoid saw question

    Hypoid is just another name for worm drive. My favorite is the Bosch. But my "regular" Bosch circular saw is fine, too, it's built many, many houses and I can see the blade just fine from either side of the saw. Not all "regular" circular saws are as well designed.


    Steven
    Last edited by StevenBauer; 04-06-2010 at 05:52 PM.

  4. #4

    Default Re: Hypoid saw question

    I've got an old Skill 77..... Any saw you have to change the oil in is OK by me

  5. #5
    Join Date
    Apr 2000
    Location
    Southampton Ont. Canada
    Posts
    6,572

    Default Re: Hypoid saw question

    The way I see it,a wormdrive is "easier" to control because your back hand is more in line with and well behind the blade as compared to a sidewinder(kind of a stupid nickname considering that the wormdrive winds sideways when you start it).
    BTW,the Bosch is a very close sister to the Skil.
    R
    Sleep with one eye open.

  6. #6
    Join Date
    Nov 2008
    Posts
    28,299

    Default Re: Hypoid saw question

    Hypoid gear:




    Worm gear:



    Not the same.

  7. #7
    Join Date
    Apr 2003
    Location
    Dallas and points north
    Posts
    7,636

    Default Re: Hypoid saw question

    http://www.duckworksmagazine.com/03/...p/01/index.htm

    A Hypoid gear drive is similar in design to the worm gear drive found on most other circular saws, but they differ in a couple of ways. The hypoid drive runs on a heat-treated finer-toothed gear, increasing the surface contact ratio and allowing for better power transfer and a cooler drive system. The hypoid gear is also sealed and factory lubricated, where a worm gear drive requires periodic oiling for maintenance. Makita claims that because of these two factors their saw cuts thicker and lasts longer than the competition.

    RodB

  8. #8

    Default Re: Hypoid saw question

    Regular sidewinder is great for us south-paws; I find the worm drive awkward and would rather work little harder with the sidewinder. Of course I ain't using it all day any more either.

  9. #9
    Join Date
    Sep 2003
    Location
    Reedville, OR
    Posts
    11,415

    Default Re: Hypoid saw question

    In my experience, relative to the skil wormdrive and inferior copies, the Makita hypoid jumps more when you pull the trigger. It accelerates faster to a higher rpm. It is also a bit lighter and therefore bucks harder when pinched. All of this doesn't matter much and may even be desirable when working in a civilized manner on sawhorses with two feet on level ground, but if you pin the guard back, turn the saw upside down, wrap one leg around a rafter while the other one claws thin air, lean out over a three story drop onto a garden of uncapped rebar to trim the underside of a rafter tail six inches from your nose, you may appreciate the distinction.

  10. #10
    Join Date
    Aug 2003
    Location
    Eugene, OR
    Posts
    1,028

    Default Re: Hypoid saw question

    Quote Originally Posted by L.W. Baxter View Post
    but if you pin the guard back, turn the saw upside down, wrap one leg around a rafter while the other one claws thin air, lean out over a three story drop onto a garden of uncapped rebar to trim the underside of a rafter tail six inches from your nose
    Oh god the memories. May I never have to do that again!

  11. #11
    Join Date
    Jan 2003
    Location
    New Zealand's Far North
    Posts
    8,637

    Default Re: Hypoid saw question

    Yep, I know what you mean!
    If you cant make it accurate, make it adjustable.

  12. #12
    Join Date
    Jan 2006
    Location
    Arkansas
    Posts
    697

    Default Re: Hypoid saw question

    Quote Originally Posted by Rob Stokes, N. Vancouver View Post
    I've got an old Skill 77..... Any saw you have to change the oil in is OK by me
    I have one of these, what weight oil is recommended?

    Can you cut a circle with yours?

  13. #13
    Join Date
    Sep 2003
    Location
    Reedville, OR
    Posts
    11,415

    Default Re: Hypoid saw question

    Quote Originally Posted by Tom M. View Post
    Oh god the memories. May I never have to do that again!
    I forgot to mention the part about feathering the trigger with your pinky finger. That's the moment when you really don't want a jumpy saw.

    Then there's the blood vessels pounding in your head, the sawdust in your eye, the rain running down your neck, the plumber asking you to move your truck, and the guy with the hardhat and the clipboard who says "can I get you to come down from there."

  14. #14
    Join Date
    Jul 2009
    Location
    Charleston, South Carolina, U.S.A.
    Posts
    26

    Default Re: Hypoid saw question

    Don't forget that many saws are available left and right handed. You're not going to maybe find them at the big box stores, you'll probably have to order them. I'm left handed and have found uses for all of the better quality saws over the years. I really don't see a difference in lifespan any more between a really good sidewinder and a worm/hypoid.
    I recently very sadly lost my Milwaukee sidewinder, a trusty companion for almost 20 years, not to old age, I ran it over with a 25000 lb fork lift! Idiot.
    I think a lot of the reputation of the worm drive comes from a time when they were the only real "heavy duty" saw. Today I think we have a lot more options and sidewinders are being built better.
    I've spent a lot of hours pushing circular saws through some tough lumber, making planks for big ships. There's not much more demanding work out there, full depth ripping oak and tropical hardwood planks 20, 30, 40 feet long. I've burned up more than my fair share to. Can't say any seemed worse than the others. The big Makita saws (10"/12") are actually maybe my favorites for these jobs. They are rebuildable motors too, which is nice when the smoke starts coming out.

    I will say I have one of the new Bosch worm drive saws and don't like it at all. It has the stupid plug the extension cord into the handle function which broke immediately. The guard is very stiff also. And I bought it in hurry at Lowes so it's got a left blade when I need a right. Anyone want a saw cheap?

    I have used the Bosch and Skil worm drives side by side fitted with the "Big Foot" saw adaptors 10" conversion and burned them both out in about the same time. So no difference there.

    Definitely wrist angle/hand position is an advantage on worm drive, but then that is counteracted with added weight. I think there is no one "all round" perfect saw.

    A friend just got a new DeWalt sidewinder that pretty nice, very powerful and superlight.

    Jonathan

  15. #15
    Join Date
    Apr 2000
    Location
    Babylon, N.Y. USA
    Posts
    1,537

    Default Re: Hypoid saw question


    SKIL 77 on right, 12" on left. I've also seen dockbuilders with the pneumatic version of the 12" saw.

  16. #16
    Join Date
    Dec 2008
    Location
    Richmond, VA
    Posts
    1,934

    Default Re: Hypoid saw question

    O.K., now you've made me want to get one o' these bad boys. I am, after all, a tool junkie.

    I have a couple old circ saws that are like battleships. They are old B&D saws, with aluminum housings. Probably from the 1960's. But they are "sidewinders", not worm drive. I have acquired all of them from garage sales/barn sales. Paid $5 for one, $14 for its twin (both 7-1/4" saws) and more recently acquired their smaller cousin, a 6-1/2" model (I think that's the size) for FREE. All they needed was a little cleaning, and to replace the dry-rotted cord (one had a stuck trigger, which was easy enough to fix - the handle is all aluminum and has a side panel held on with two screws - open it up, take the trigger apart, straighten the bent bit, and clicky-clicky, it works perfectly).

    Considering they're all probably about 40 years old (or more), and how cheap they were, they have lots of power and run great. Can't imagine many of the consumer-grade plastic ones these days will be running at all in 10 years, let alone 40 or 50.

    But of course, now I "need" a worm-drive. (sigh) Always something to be looking for to spend money on...
    - Bill T.

    "How many politically-correct people does it take to screw in a light-bulb?"

    "Look, I don't know, but that's not funny."

  17. #17
    Join Date
    Aug 2018
    Location
    grove ok usa
    Posts
    2

    Default Re: Hypoid saw question

    Quote Originally Posted by StevenBauer View Post
    Hypoid is just another name for worm drive. My favorite is the Bosch. But my "regular" Bosch circular saw is fine, too, it's built many, many houses and I can see the blade just fine from either side of the saw. Not all "regular" circular saws are as well designed.


    Steven
    Old thead but I had to chime in on this comment anyway. Hypoid and worm are both 90 deg gear boxes but other than that they have significant differences in durability. Worms typically use a brass gear and steel pinion...the brass wears eventually and you need to change lube occasionally if you want long gear life. Hypoids have hardened steel gears and pinions and will last much longer and require fewer lube changes if any.

  18. #18
    Join Date
    Jul 2000
    Location
    N.E. Connecticut.
    Posts
    6,405

    Default Re: Hypoid saw question

    I have a Skil 825 that my dad bought used in the late 60ís. It will still rip a 10ft plank of 9/4 mahogany without slowing down. A great saw.
    Attached Images Attached Images

  19. #19
    Join Date
    Jan 2010
    Location
    Petaluma, CA
    Posts
    2,573

    Default Re: Hypoid saw question

    I love my Skil worm drive. Not sure what model it is, but is is a beast! Easy to manage (other than being ready for the startup twist), and the combination of power and geometry (both talked bout up above on this thread) mean that it is easy to hold a good line.

    The other great tools is a 1/2 inch drive hand drill. Put those little 3/8 weiners to shame! I have a Dwalt that has drip and hammer modes. That sucker will drill through anything!

    Cheers,

    Scott
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

  20. #20
    Join Date
    Jan 2010
    Location
    Petaluma, CA
    Posts
    2,573

    Default Re: Hypoid saw question

    Quote Originally Posted by nedL View Post
    I have a Skil 825 that my dad bought used in the late 60’s. It will still rip a 10ft plank of 9/4 mahogany without slowing down. A great saw.
    THat's a well used saw! Love the box!
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

  21. #21
    Join Date
    Aug 2018
    Location
    grove ok usa
    Posts
    2

    Default Re: Hypoid saw question

    Quote Originally Posted by Cogeniac View Post
    I have a Dwalt that has drip and hammer modes. That sucker will drill through anything!

    Cheers,

    Scott

    Bet that thing makes a great cup of coffee!

  22. #22
    Join Date
    Mar 2018
    Location
    Virginia
    Posts
    3

    Default Re: Hypoid saw question

    I have a couple of old skils. I have a 7 1/4 and a 10 1/4. Im still trying to find a 12" at a decent price and then I'll start working my way down in size. I like, and prefer, the older work gear saws. Just something about keeping an old tool working and working well I guess.

  23. #23
    Join Date
    Jul 2011
    Location
    Lindstrom, MN
    Posts
    2,699

    Default Re: Hypoid saw question

    Quote Originally Posted by oznabrag View Post
    Hypoid gear:

    Worm gear:

    Not the same.
    The problem with 8 year old threads and pictures stored on sites that will change.
    Hypoid gear:
    MagSaw_Motor.jpgMakita
    Worm gear:
    worm-gear-saw-dws535t-7-14-184mm-worm-drive-circular-saw-w-twistlock-plug.jpgDewalt

    According to https://www.toolsofthetrade.net/powe...-hypoids_o?o=2
    The convincing part of their argument is that hypoid saws use a sealed motor, which means no gear oil to change. With a wormdrive you need to change the gear oil. The reason? Same as your truck. The worm gear wears, and tiny metal fragments are released into the oil. Dump the oil, out go microscopic chunks of your gear system. Add some new oil and you're good to go. The hypoid, with its all-steel guts, doesn't have this problem. One tank of oil and it's good for life.

    A professional framer checks his oil pretty regularly, changing it every few months, so not having to change oil saves a step, though someone who doesn't frame day in and day out may go a long time without even knowing there's oil in the saw. A framer also will be watching through the breather fins on the back of the tool for sparks. If he starts seeing a lot of light, its time to change the brushes, too.
    Worm gears don't back drive, which is an advantage where back drive is more important than efficiency and wear, but that is not the case in a saw. The reason that they don't back drive is that there is too much friction in the gear. All the sliding contact and friction results in low efficiency and the gear generates a lot of heat. In a cordless tool that would substantially reduce the cutting time. The only cordless worm drive style saws that I found (in a very limited search) was a Makita with a "hectile" (Modified Hypoid) drive and a DeWalt that was not a worm, but doesn't say what it really is.
    Last edited by MN Dave; 08-13-2018 at 08:49 AM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  24. #24
    Join Date
    Jun 2018
    Location
    Los Angeles CA USA
    Posts
    192

    Default Re: Hypoid saw question

    Quote Originally Posted by MN Dave View Post
    This is horse pucky. Hypoids wear just like wormgears, ask anyone with an old car. One advantage of the worm drive; if the tool gets to be fifty years old and you want to rebuild it, people can make new worm drives. You can forget about making a replacement hypoid.

    In real life, no difference.

    p.s. Those don't look like hypoids anyway. They look like spiroids. Face width on the pinion is too long, for one thing.

  25. #25
    Join Date
    Jan 2003
    Location
    New Zealand's Far North
    Posts
    8,637

    Default Re: Hypoid saw question

    My understanding of the term 'hypoid' is that it refers to a right angle gear drive which has the pinion axis not intersecting with the axis of the larger gear. The pic of the electric motor above illustrates the salient point.
    If you cant make it accurate, make it adjustable.

  26. #26
    Join Date
    Jun 2018
    Location
    Los Angeles CA USA
    Posts
    192

    Default Re: Hypoid saw question

    Quote Originally Posted by Stiletto View Post
    My understanding of the term 'hypoid' is that it refers to a right angle gear drive which has the pinion axis not intersecting with the axis of the larger gear. The pic of the electric motor above illustrates the salient point.
    Your understanding is incorrect. When you've cut gears for fifty years and owned Gleason machines, comce back and we'll talk. The pinion doesn't have tapered teeth, which is one giveaway. These are in the spiroid family (thre were a few variations), a name trademarked at one time by Illinois Tool Works. They are made differently and have different geometry.

  27. #27
    Join Date
    Mar 2017
    Location
    Waterbury Center, Vermont
    Posts
    91

    Default Re: Hypoid saw question

    Worm drive saws, in my experience, are too heavy, jump when you pull the trigger and the base is too small. The Makita non-worm drive have always worked for me. I have abused them in ways that beggar the imagination and remain satisfied. I have deep respect for anyone rugged enough to live with a worm drive unit.

  28. #28
    Join Date
    Jul 2011
    Location
    Lindstrom, MN
    Posts
    2,699

    Default Re: Hypoid saw question

    Quote Originally Posted by on the border View Post
    This is horse pucky. Hypoids wear just like wormgears, ask anyone with an old car. One advantage of the worm drive; if the tool gets to be fifty years old and you want to rebuild it, people can make new worm drives. You can forget about making a replacement hypoid.

    In real life, no difference.

    p.s. Those don't look like hypoids anyway. They look like spiroids. Face width on the pinion is too long, for one thing.
    If we are going to eschew civility, take your horse pucky to the bilge. I created a wastebasket thread for experts just like you who like thread drift and insulting people. TITTB #3 I don't care if you go there and rant, and no one else has to read your rant if they are interested in saws.

    All gears wear, but the wear mechanism is entirely different with worms. Worm wheel contact action is pure sliding with no rolling. Other gears are subject to rolling and sliding. A well designed worm is about 85% efficient whereas a similar hypoid and bevel gear can be 96% efficient.

    The Makita looks more like the hypoid than the spiroid to me, but that difference it irrelevant to the efficiency argument.
    02-ITT-spiroid-helicon-in-context.jpg
    Picture from https://www.motioncontroltips.com/what-is-a-gear/
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  29. #29

    Default Re: Hypoid saw question

    I can see worm drives cutting curves better, just try and cut a straight line with one. California framers loved the worm drives, drop them on a 2x4 and it's cut. But framers don't have rep for fine quality work either. I wouldn't even call them carpenters. Carpenters who worked on concrete forms if they didn't dislike worm drives, they hated them. Just try and make a straight cut on a sheet of plywood. We would get another sheet of plywood and use the edge as a straight edge guide. Talk about three times the time and twice as much effort, all with 3/4" sheets of plywood. With care and a good sidewinder like the old Skil 534 or the Makita 5007 clone you could make a cut that rivaled a track saw. Many an old carpenter built the kitchen cupboards with a Skilsaws. Because the handle and balance is so far back on a worm drive,they are very difficult to guide. And the blade is on your leg side. The handles of the Rockwell and it's copy the Milwaukee were on top and they weren't as easy to get a straight cut either, just not as difficult as the worm drive. That's why the Skil 534 were so perfect.

  30. #30
    Join Date
    Jun 2018
    Location
    Los Angeles CA USA
    Posts
    192

    Default Re: Hypoid saw question

    Quote Originally Posted by MN Dave View Post
    If we are going to eschew civility, take your horse pucky to the bilge. I created a wastebasket thread for experts just like you who like thread drift and insulting people.
    Yeah right. Sorry for the photo quality, only one I could find (need to do something about the hard drive, it's worse than old mother Hubbard's cupboard !) At the top, green thing, my (first person possessive pronoun) 12,500 lb Gleason 16 rougher-finisher. Behind the GCI to the right is the 17A lapper-tester and behind that, the cutter sharpener. 'Insulting' is when people say stuff that's not true.

    When you've physically put your hands on a spiral bevel machine, you may come back and give me lessons.

    e.jpg

    All gears wear, but the wear mechanism is entirely different with worms.
    Wikipedia blabla. In this case there is no practical difference. Downwindtracker has it right, functional differences matter but worm or spiroid, no realworld diff. It's pure marketing. Even the people who invented spiroids don't go into this "efficiency" nonsense.

    The one reason I might like the worm drive better is that in ten years, if you really love that saw, you could have a new one made. The spiroid, forget it. Garbage can time.

    (Yes they could be hypoids but from the photo, not likely. Plus hypoids are generally slower to make, which makes them more expensive, which is verboten in today's world.)

    Now I gotta go play with the current project, c'mon wind energy !

    gasher.jpg
    Last edited by on the border; 08-14-2018 at 08:37 PM.

  31. #31
    Join Date
    Jan 2003
    Location
    New Zealand's Far North
    Posts
    8,637

    Default Re: Hypoid saw question

    Quote Originally Posted by on the border View Post

    When you've physically put your hands on a spiral bevel machine, you may come back and give me lessons.
    The lessons you more obviously need are in how to discuss things in a civil manner! Keep your ego out of it.
    If you cant make it accurate, make it adjustable.

  32. #32
    Join Date
    Jul 2011
    Location
    Lindstrom, MN
    Posts
    2,699

    Default Re: Hypoid saw question

    Quote Originally Posted by on the border View Post
    Yeah right. Wikipedia blabla. Even the people who invented spiroids don't go into this "efficiency" nonsense. c'mon wind energy !
    Nice Jag. Yours?

    TITTB#13 I just replaced some old pictures and provided some information on the alternative gearing. You are of the opinion that the wear life of the hypoid will not be as good as the worm. Are you a machinist or an engineer? The efficiency numbers are real. I did the calculation and the link I provided confirmed my estimate. Battery life is very important, so the more expensive gear makes economic sense for a cordless saw.

    Since you are an expert on worm drive saws, maybe you can answer some questions. Why do you need to change the oil? How often should you change the oil? What kind of oil? Why is worm oil different from standard gear oil?
    Last edited by MN Dave; 08-15-2018 at 02:25 AM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  33. #33
    Join Date
    Jan 2010
    Location
    Petaluma, CA
    Posts
    2,573

    Default Re: Hypoid saw question

    Quote Originally Posted by MN Dave View Post

    Since you are an expert on worm drive saws, maybe you can answer some questions. Why do you need to change the oil? How often should you change the oil? What kind of oil? Why is worm oil different from standard gear oil?
    Now boys.. Let's play nice..

    First off, worm oil is totally different from standard gear oil. Worm oil is harvested from the rare Driloleirus americanus worm (https://en.wikipedia.org/wiki/Giant_Palouse_earthworm). Standard gear oil is usually harvested from Pep Boys.

    This discussion reminds me of some of the flame wars on the DIY audio forum, where folks wax poetic about the virtues of various snake oil devices designed to create unobtainium improvements in audio quality.

    I am sure the hypoid gear is more efficient than the worm drive. Not sure how much a 10% difference in overall gear loss will affect battery performance though. I am sure differences in wood density, thickness, etc. will all contribute a lot more to the battery drain than any gear friction. Look at it this way. If the saw was 100% efficient, then the blade would spin indefinitely, other than wind resistance. We know that doesn't happen. The blade spins down over about 3-5 seconds. Let's assume the overall assembly is 90% efficient. that means 10% of the energy goes into overriding friction in the motor, the bearings and the gears. If this is the case (and I would suspect the brushes in the motor are a major contributor to this friction), then the 11% difference in gear efficiency quoted by MNDave above translates to a 1.1% impact on battery life. Not really much to write home about. And that's assuming that the gears are the dominant source of friction. If the brushes contribute 90% of the losses, then the gear losses represent less that 1% of the overall drain, and the difference between gear types is then less than 0.1%.. So I think we are splitting hairs here.

    One advantage of the worm drive is that the saw blade can't kick back and affect the motor. That sort of dynamic can cause the saw to jump when the blade binds because the momentum of the motor gets disrupted. In a worm drive the frame of the saw (and the gear) takes up that shock.

    I have quite a different experience than Downwindtracker. I find that the worm drive cuts MUCH straighter than the sidewinder. I am not sure if this is because of the handle or the saw. I am pretty certain it is not related to the drive mechanism.. I think having the handle well aft of the blade, and more in line with the blade make it easier to maintain the blade in a straight line. I would think that would also make cutting curves somewhat more difficult, since you are "steering" the saw from a position well back from the blade axle. It is the opposite problem with the sidewinder. In a sidewinder saw, the handle is almost on top of the blade axle, so the "steering" is very quick. My experience is that it is very challenging to cut a really straight line with a sidewinder. With experience, you can follow a straight line, but at a micro level the cut usually has 1/32 or so of wiggle. Try cutting a 45 degree miter on a piece of ply and see what sort of corner edge you get, and you will know what I am talking about. That wiggle though, presumably also translates into better curve cutting ability (to the extent that one might try to cut a curve with a circular saw..)

    my 2 cents.

    Scott
    Last edited by Cogeniac; 08-15-2018 at 09:32 AM.
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

  34. #34
    Join Date
    Jun 2018
    Location
    Los Angeles CA USA
    Posts
    192

    Default Re: Hypoid saw question

    Quote Originally Posted by Cogeniac View Post
    First off, worm oil is totally different from standard gear oil. Worm oil is harvested from the rare Driloleirus americanus worm (https://en.wikipedia.org/wiki/Giant_Palouse_earthworm). Standard gear oil is usually harvested from Pep Boys.
    For larger gears hypoids usually have extreme pressure agents, because of the large amount of sliding. Those additive attack bronze, so those oils are not suitable for wormgears. Oldsters would recognize the word "steam oil" as one having no additives.

    In real life, no one would be using 90 weight extreme pressure oil for a skilsaw anyhow, so not much of an issue. 3-in-1 would probaly work okay.

    This discussion reminds me of some of the flame wars on the DIY audio forum, where folks wax poetic about the virtues of various snake oil devices designed to create unobtainium improvements in audio quality.
    Exactly. It's silly. The whole "debate" is about a marketing campaign.

    I am sure the hypoid gear is more efficient than the worm drive.
    I wouldn't be so certain about that. I'll come back to this in a sec ...

    Not sure how much a 10% difference in overall gear loss will affect battery performance though.
    Hey ! Whatchoo doin', gettin all rational and stuff ?

    One advantage of the worm drive is that the saw blade can't kick back and affect the motor.
    Didn't think of this but you and downloadtracker have this figgerred out. If there are any functional differences, it's going to be because of the layout of the saw, not because of any mythical superiority of hypoid gears.

    Wasn't going to do this because experience has shown, talking to people who know everything is a waste of time and it annoys the pig. But maybe there's someone out there who cares about reality ...

    To begin with, I seriously doubt that the gears in question are actually hypoids. The teeth look wrong, the face width is too large, the shape isn't right. But that's just one photo, so I wouldn't bet more than a a buck-fifty on this. They really look like spiroids, which are a different animal.

    Hypoids are a pain in the rear to make. I've never done the tiny stuff but in larger ones, in volume, there will be a cell of three or four machines dedicated to making them. A rougher to chop out most of the material, a finisher for the drive side and a finisher for the coast side. Sometimes two roughers because roughing is more time-consuming than finishing. Then the teeth are lapped together and marked as sets. Anyone who has rebuilt rear ends remembers this.

    In small batches it's even worse, but the only reason that is relevant is that if a person ever wanted to rescue their grand-dad's beloved saw in the future, with hypoids or spiroids or even spiral bevels, you'd be looking at twenty minutes machine time and about sixteen hours setup and changeover time. That gets expensive. You could do a worm and wormgear in maybe four ? which is still expensive but not as ridiculous. A guy could even make his own wormgear in the garage without tooo much trouble, but forget the spiral bevel on a South Bend.

    They did use hypoids in smaller stuff (sewing machines were a big market for Gleason at one time), the process is simpler but still expensive and a pain in the ass. In use, location of the pinion is critical both axially and radially. Assembly is expensive and time-consuming. This is fine on a $30,000 car but less fine on a $129 portable saw. In fact it wasn't that fine on a $30,000 car either, one of the huge reasons Detroit went to front-drive, even though it is inferior, was to get rid of the damned expensive rear ends.

    Spiroids, on the other hand, are insensitive to axial placement and backlash is like straight bevels, just slide the pinion in towards the cone center. Manufacturing them is also way easier, it's more like hobbing but with weirdo cutters. Much cheaper to make and assembly also faster easier cheaper. The gear is probably powder metal in both cases.

    So I'ma gonna go with spiroid here, which doesn't make much difference except that the marketing scam is "Hypoids are so much better than worms !" That loses some appeal when you think, "If hypoids are so much better why didn't you use them ? These are not they !"

    My guess is because the Marketing Department wouldn't know a hypoid if it rose up out of the grunter and took a big chomp out of their ass, but their uncle Dean once had a '62 Chevelle that he rebuilt and they remembered the name. It sounds so cool and Dead Man's Curve, ya know ? Let's use it !

    Back to the irrelevant subject of losses, well ... you already hit it on the head cogen, but : our world-renowned authority on gears who just discovered that Gleason invented the spiral bevel is mistaken. (If he looks in wikipedia a little longer he may find that Kate Gleason is credited with the invention. At least she is by gear guys, who are all convinced that the devilish machines for making them had to be invented by a woman. No man is devious enough to think those things up.) Anyway, you can't "do the calculations" without having the design info. Those cute little rules-of-thumb, "Gears are 96% efficient, wormgears are 80% efficient, mice in a squirrel cage are 3% efficient" don't apply in the real world. Those are gross generalizations. In any case of mass-produced stuff, the gearset will be optimized for its purpose.

    Back to our automotive rear and as an example, There are actually two kinds of sliding involved with teeth. As the teeth enter the mesh they are moving against each other. This is approach action. Then around the middle area they roll. Then as they exit the mesh they move in the same direction relative to each other, which is recess action. Recess action is obviously going to have a lot less friction than approach action. Teeth can be modified from "standard" (in practice there actually is no "standard", it's more a term of convenience than anything else) to change their behavior. For high-volume aplications they always are. Therefore, car rear ends are designed to be mostly recess action in the forward direction. That's one reason they are a lot noisier in reverse. As saws are very seldom needed in reverse, I'ma gonna go out on a limb here and claim they are optimized for unidirectional use. Which means you can't just "do the calculations" without even knowing what the numbers are.

    This is ignoring the fact that they probably aren't even hypoids. And, no matter what they are, crossed-axis gears don't follow the rules-of-thumb for parallel axis gearing. All crossed-axis gearing has a huge amount of sliding. That's why in higher-power situations they need special lubricants.

    Worms are not exactly the simplistic mechanisms that our Marketing Boyz describe, either. They can be deisgned to be efficient. They do have a lot of sliding but so do spiral bevels. Wormgears have been used in car and truck rear ends as well. Wormgears have certain unique features that can be useful. As you pointed out, they are more resistant to back-driving. About "efficiency", it's not that simple. A dumb single-start worm that a guy made in the garage to crank up his cellar door, sure. But the chapter in Buckingham concerning wormgear geometries and efficincies is reaaaallly long and reeeeaaally involved and has pages and pages of calculus and differential equations. Nobody ain't gonna "do the calculations" on a worm set without having the prints in front of his nose.

    Long story short, the whole "efficiency" thing is nonsense. You hit it on the nose in a heck of a lot fewer words. But I can top ya now - "Marketing, Marketing, Marketing" It's bee ess. If there is any real-world difference, it's because of the layout of the saw.

    And I'm not going to go back and check the typing because this is too boring even for me
    Last edited by on the border; 08-15-2018 at 09:20 PM.

  35. #35
    Join Date
    Jan 2010
    Location
    Petaluma, CA
    Posts
    2,573

    Default Re: Hypoid saw question

    This is interesting. We had a thread a few years back on a steering quadrant (look it up, it was a great thread). The issue was twofold. Because the "rack" was semi circular, the gears were beveled, and, we all learned a lot about involute gear profiles. As I understand it, the involute profile is always in rolling contact. It is interesting that, in your description the worm is always in sliding contact, and the hypoid and spire are somewhere in between...

    And yeah, even with made ups numbers the efficiency argument falls flat unless the overall efficiency of the gears is some significant proportion of the motor brush and bearing friction, which would be pretty hard to achieve!

    S
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •