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Are these Bevel Gears DP or Metric Modules Gears, How Do I Figure This Out?

...going to take a fair amount of experience with cadcam ....
About 10 minutes work in FreeCAD to get the basic shape. From what is there, it needs a cylinder adding to the big one, the correct relative placement and the small one making thicker to get the proper tooth engagement length.

With the dimensions given, the gears are very close to 2 MOD (12.7 DP) at the large end.

That is not too much help as if you are doing the parallel depth method, you need a cutter that matches the DP/MOD at the small end, but it is possible to calculate that.bevel gears.jpg
 
That is not too much help as if you are doing the parallel depth method, you need a cutter that matches the DP/MOD at the small end, but it is possible to calculate that.View attachment 428218
That thing is totally wrong. Typical of about half the shit that's floating around about this subject here .....

I was talking about a face gear, a totally different animal than that useless drawing. What the eff is that thing ? cuz it ain't a gear in any way, shape or form.
 
EG, dang dude if you are still in the USA you need to find some better weed, if in China go bang a hottie or at least get a massage. Being that angry all the time is not good for your heart.

2 sets of cutters ordered, one DP, one Module, if none fit close enough at least I'll know to order something in next size larger/smaller. Maybe I'm not understanding "parallel depth" term, these are shallow at ID, deep at OD. Books should be here by end of week, that will give me some reading time before cutters arrive. Yes, I did consider 3D printing, I have no idea how to model a gear in any form on a computer, I don't know how to write the program, I don't have access to a printer, and I'm pretty sure learning that will take me longer than some trial and error doing it the old fashioned way.

Do y'all want to see the f'ups or just the good enough one :D
 
Being that angry all the time is not good for your heart.
Because 2/3 of these posts are stupid. Bla bla bla from everyone on the planet, almost all of it totally wrong and ignorant. What the fuck do hypoids have to do with this ? Bla bla bla bla almost all pointless.

2 sets of cutters ordered, one DP, one Module, if none fit close enough at least I'll know to order something in next size larger/smaller. Maybe I'm not understanding "parallel depth" term, these are shallow at ID, deep at OD.
Bevel gears are cones. The teeth and roots taper from the apex of the cone. That's why NO space cutter can be correct. A cutter cannot get smaller and bigger as it traverses the length of the tooth. Physically impossible. So you can't buy a correct cutter because there isn't one.

Bevel gears don't even have involute teeth, so right off the top a majority of these remarks are pointless. At least I don't give lessons on a game they play in afghanistan from horseback with a stick and a rabbit's head, because I don't know a fucking thing about it. Maybe some other people could learn that skill.

All you can do is try to get something sort of close at one point, and then hand file the teeth to a shape that rolls.

That's what all those directions in hundred year old books are for - faking it. Which is fine, but kind of like making wood spoke wheels. Which is probably fun, but they aren't going to work well on your 2010 Toyota with disk brakes and low profile tires.

Yes, I did consider 3D printing, I have no idea how to model a gear in any form on a computer, I don't know how to write the program, I don't have access to a printer, and I'm pretty sure learning that will take me longer than some trial and error doing it the old fashioned way.
That's what I figured and why the Freecad model wasn't going to be helpful even if it had been right, which it wasn't, not by any stretch of the imagination..

Pointless fucking garbage, may as well be Home Shop Harry Does Bevels. People don't even bother to find out how they work before running off at the mouth.

Do y'all want to see the f'ups or just the good enough one :D
I'd just as soon see you file a 1-2-3 block, then scrape it square in all directions. At least that'd end up with something nice.

A face gear could be interesting. That might be a solution for other people with this problem. The other is just "yay, I put a mounds bar down the plug hole, now I got compression again !"
 
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Bevel gears have been used for hundreds of years and before Miss Gleason invented her machine, they were imperfect however they worked.
I have made them on a miller by the two or three hundred cut method described and produced adequate gears, I prefer to go for 3 cuts.
Remember the cut deepens towards the outside of the blank as well as widening. The way I set up is to machine the blank to a point- a true cone at the outside tooth angle then set it in the dividing head at the root angle, the cutter can then be aligned with the point on the blank and just touching it
Start milling and the tooth depth will come right, after going round once you then need to widen the outside end of the gullet, what I do is to work out the offset, leave the cutter engaged in the gullet at the outside, slacken the chuck to allow the blank to turn, wind over by the offset and go round again and repeat for the other tooth blank.
All very crude but it works.
 
Books should be here by end of week
If you wanted to get a jump on the books, the Internet Archive books in the link above on the Model Engineer forum are the original works on the parallel depth method. Anything newer than them is derived from them.

In the model engineering world, there is a model of the Shay locomotive, that uses a number of bevel gears. The methods used there might be useful to you (https://www.modelenginemaker.com/index.php?topic=9935.0 - but note that there is a mistake in one of the diagrams somewhere in that thread).

The people who make model traction engines also use bevels in the rear differential, so that is another area to explore (Post 35 here: https://www.modelenginemaker.com/index.php?topic=5008.30). See also: https://www.laughing-dog.co.uk/model_eng4.htm

The most important thing to understand if going this route is that you have to size the cutter for the small end of the tooth. After all, it is possible to make a narrow cutter cut wider. It is a challenge to make a wide cutter cut narrower.
 
I found the relevant patent, from the 1930s. It's US1937628A, Method of and machine for producing gears, Candee and Carleson. It is assigned to the Gleason Works, but I assume that Gleason had passed away by then.

Use Google Patents to get a copy.
 
I can vouch for the three cuts per space method as described in Ivan Law book. I made multiple sets of nylon/nylon bevels/pinions for proof of concept of molded gears. I designed them so the small ends fit a standard involute gear cutters. 1.5 module if I recall and about 4:1 ratio, up to 3000rpm on the pinion, and 100 watts power. Worked great. If you are trying to mate with an existing gear it may not work as well. Can you make both gears?

Production design was injection molded and proper bevel gear geometry.
 
Anyone care to explain the term "parallel depth"?

Looking at the pics of the gears shown in the links of post# 47, it looks to me that the height of the teeth is the same at the ID as it is at the OD, and as such the cutter must fit at the ID. Looking at the gear I need, the depth at the ID is approx 1.5mm, and the depth at OD is approx 3mm. With a little more thickness on the face of the gear, the depth of cut would taper to 0 at the ID. It looks to me that a single cutter made a single pass and the difference between the face angle and the cut angle created the tapered depth of the cut and resulted in the teeth being taller at the OD. It is quite possible that after doing a single cut, at the correct angle and depth, that it will become crystal clear to me that that is not the way this gear was cut.

I have also considered that this may not be the original gear, and I may be trying to copy someone else's best approximation of the original.

Could I make the pinion too? I can see it would be more difficult, and most likely require the 3 pass method to get anywhere close, and according to some of y'all, still not correct.
 
Bevel gears are cones. The teeth and roots taper from the apex of the cone. That's why NO space cutter can be correct. A cutter cannot get smaller and bigger as it traverses the length of the tooth. Physically impossible. So you can't buy a correct cutter because there isn't one.

We - well a lot of us - KNOW all that.

However, we also know that the perfect is the enemy of the good.

It's a fucking very low speed low power transmission issue. It DOES NOT MATTER if the gear is not perfect in every way.

It just has to mesh reasonably well and rotate.

The hack methods are perfectly adequate for that. I've done it. It worked.

So fuck off out of this thread, take your blood pressure meds and go look at pictures of old steam-powered tugs. You'll feel better. And even if you don't, we will.

PDW
 
We - well a lot of us - KNOW all that.
No. The evidence is you don't know that, as documented by the stupid stupid stupid claims made here several times. Many many things said that are wrong and even when reality is pointed out, people insist that shit on a shingle is really raisin toast.

Well it isn't. It's still shit on moldy old bread.

The hack methods are perfectly adequate for that. I've done it. It worked.
That's not the point. Doing a crap job is fine, not my lathe who cares. But insisting on things that are wrong wrong and wrong, no matter how many times the facts are explained ... fine. If this place wants to disseminate horseshit, not my problem. But the bunch of you are morons.

So fuck off out of this thread,
You go fuck off, back to rec.crafts.metalworking or whatever home hobbyist place you came from. Even if you don't have the tools to make something correctly, a professional at least understands what is required. Which you still don't.
 
took longer than i see now. not days, or hours...I did cheat and use gear generator instead of drafting out the involute for a single tooth at the base of the gear. Not hard to figure the tooth taper if you start with a rack, bend it to a cone unwrapped flat, measure tooth to tooth id and od. Have to do a single tooth to maintain depth of root, at least in my software, then array it.
racks.jpgbevelb.jpg
 
took longer than i see now.

Please, I do not want to criticise, but I am not sure that is correct. It appears that the angle of the gear is roughly 45 degrees. That would only be so if the two meshing gears have the same number of teeth. I think from the original post that one gear has 54 teeth and the other has 20 teeth. You can see in the photos that the larger gear is very 'flat'.

Hence, you have to draw a right angle triangle with base 54 units and vertical side 20 units to determine the angle. You can write the angle as a parameter: arctan(20/54) for one gear and arctan(54/20) for the other.

Please let me apologise in advance if this post causes our sweary friend to pollute this thread with more of his unwanted ranting.
 
Oh stick it. Ash is a bunch of creeps and every single goddamned "cutter" in their effing catalog won't help even a tiny little bit for this problem.
EG said
If you knew doodly-squat you'd just keep your mouth shut on this particular project.
[/QUOTE]


EG: When I wrote post #17, not much had been said about the narrow cutter and three pass method.
Knowing that I had seen the narrow cutters listed somewhere; I thought that might be useful information for someone.

After reading this whole thread ; I now recall that much of that information was patiently explained to me by the people at Ash Gear
about thirty years ago.

I am sorry that your experience with Ash Gear has not been as pleasant as mine.
It appears to me that you must be a very sensitive guy whose feelings are easily hurt.

By the way:

How'se ol' Doodly do'in these days ??

Since I have only a passing acquaintanceship with him.....
and you'd like to be known as the only guy around here that knows Doodly;

Please greet him for me and say "HI" on my behalf when you next see him.


petersen
 
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Hence, you have to draw a right angle triangle with base 54 units and vertical side 20 units to determine the angle. You can write the angle as a parameter: arctan(20/54) for one gear and arctan(54/20) for the other.
It was just a cone gear drawing… that and I always like the ruled edge challenge. 41 teeth because the return rail throwing me fits last night was 41 inches long on center. 45 degrees because that should show any non-ruled feature the most. 1 inch thick, because a default offset I use a lot.

Special sale on a rail 39.5 inches long with return stubs down at 32.5 degrees. Also one the same at 39.75. Rail kit…

Parallel depth means same depth of gullet top to bottom. This is the hardest part to compensate for in the cad side, no just scaling tooth option.

There is a very small difference between top and bottom width. Too much to ignore, a fair bit to file out, yet two passes looks to be fine depending on the cutter.
I thought you had a prototrak or similiar? Set indexer pointing down x axis titled to the incline of 1/2 the tooth taper. Run pass on y+ side with xy making a line angled to cone taper. The cutters top edge would be center of rotation. After all teeth done move over to y- side while changing cutter height to bottom edge cen of rotation. The taper will come out semetrical to center of gullet.
I think the above would work, at least it does in my head. I am still unsure about cutter z placement above or below center. That is what test parts are for.
Do not buy a cutter from them whatever you do! It can only be had from the other places…
 
The gears are module, or at least that is the cutter with correct profile. Are they correct? Without specifications I don't know, but they are "good enough". Made up 10 blanks, used one to take test cuts to find correct face angle, cut angle, depth of cut, and correct cutter, after that it was i hour per gear. Glad this job is done! Yes, I did learn a few things along the way, and would do a lot different if I had to do it again. Made a few extras to sell, but want to run one for awhile before I sell them, if they are not right I might need the spares :D
 

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