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bytewise
06-09-2012, 03:20 PM
I can't help brag a little. Attached are pictures of some helical gears I made for a project. The large diameter gear has a helix angle of 63 deg. and cannot be cut in the conventional helical setup. The other pictures show the setup I used to cut that one. Link is http://s1258.photobucket.com/albums/hh587/bytewise

gbritnell
06-09-2012, 03:34 PM
You need to store your pictures on a web hosting site like Photobucket. You then take the link under the picture, copy it and then paste it into your thread.
gbritnell

gbritnell
06-09-2012, 03:36 PM
If you look right at the top of this category you will see a 'sticky' about posting pictures from Photobucket.
gbritnell

alanganes
06-09-2012, 04:30 PM
Yikes! Brag away, that's awesome work. The setup is really something, very nice work for something done without a dedicated machine.

Amazing thing is that most people would see those gears and not give one moments thought as to what it might take to make them. Did you make these for a work project, or just for "fun"...?

More details and background would be appreciated by many here, I suspect. Thanks for posting that!

bytewise
06-09-2012, 04:58 PM
They are for a private project. I am retired. I have been helping at the an antique machinery museum, restoring tools and exhibits. The work there has slowed. I decided to try to make a working scale model of a rather unique experimental marine engine. I have not spoken about this project in public until now in case it became impossible! I am far enough along that I guess I am committed now!!
The experimental engine was designed and built in 1914 by the Doxford company in Scotland. The engine is a diesel engine with two opposed pistons in one cylinder. After the war, in 1020 they started production of multi-cylinder versions for ship propulsion. They also built the ships. There is a lot of information about the Doxford company on the webl
I have been making detailed drawings for the model from crude information obtained from the web. I decided to try to make a couple of the tricky parts that will be needed even before the drawings are complete. So far there are no 'show stoppers'.
Comments and queries are welcome. Hugh

Black_Moons
06-09-2012, 05:08 PM
Haha! those are awesome gears. I have never seen helical gears meshed like that before. Wonder how well it works? seems to me its going to need some serious lube like that used on worm gears.

uncle pete
06-09-2012, 05:09 PM
That's not bragging, You well deserve every attaboy you get. And that isn't exactly an easy setup to do. It's pretty rare today to see a universal mill along with a universal dividing head and someone that knows enough to set them up to do the parts you've shown. I'm more than impressed.

Pete

strokersix
06-09-2012, 05:16 PM
Haha! those are awesome gears. I have never seen helical gears meshed like that before. Wonder how well it works? seems to me its going to need some serious lube like that used on worm gears.

Crossed-axis helical. Commonly seen in oil pump and distributor drive for automotive engines. Works just fine if you take into account the smaller contact area and high sliding velocity.

lazlo
06-09-2012, 05:43 PM
Yes, very brag worthy!

Hope this helps:

http://i1253.photobucket.com/albums/hh587/bytewise/Helical6.jpg

http://i1253.photobucket.com/albums/hh587/bytewise/Helical5.jpg

http://i1253.photobucket.com/albums/hh587/bytewise/GearsUnevenSize.jpg

http://i1253.photobucket.com/albums/hh587/bytewise/GearsEvenSize.jpg

Black_Moons
06-09-2012, 06:42 PM
LOL! is it just me, or is the ratio still 1:1 even with the larger and smaller gear? Thats just crazy :)

alanganes
06-09-2012, 06:49 PM
That's not bragging, You well deserve every attaboy you get. And that isn't exactly an easy setup to do. It's pretty rare today to see a universal mill along with a universal dividing head and someone that knows enough to set them up to do the parts you've shown. I'm more than impressed.

Pete

Second that. I think the saying goes: "It's not actually bragging if you can really do it!"

Certainly applies here.

gbritnell
06-09-2012, 07:15 PM
Helical gears change diameter when the pitch angle changes. A camshaft to distributor set are different diameters but have the same tooth count. I found this out when making my model 302 engine.
gbritnell

Tamper84
06-09-2012, 08:28 PM
Wow I can only wish to do that!

wierdscience
06-09-2012, 08:43 PM
Very well done gear set!

mike4
06-09-2012, 09:49 PM
Very good setup and excellent results , you are someone to be admired for , getting up and having a go.
Michael

oldtiffie
06-10-2012, 12:50 AM
+1

I am not sure how many appreciate the math that goes into the gear blanks, the universal dividing head drive gear train and the machine set up.

Top class job from end to end.

Wayne A Thackery
06-10-2012, 01:43 AM
Bytewise,

A very nice job indeed! Where can I learn how to do the calculations to cut gears like this. I have a universal head and universal dividing head for my K&T #3 mill. Is there a book that explains how to do this?

Thanks, Wayne

oldtiffie
06-10-2012, 02:00 AM
Sorry I can't advise an easier path but "Machiney's Hand Book" (in my case 27) "Helical Gearing" (page 2009) is an excellent reference but it can be very "heavy" going to plough through and to comprehend.

I'd suggest mastering spur hears first if you haven't already as it is a very good stepping stone to gears generally.

There will be calculators on the web.

MHB also addresses the gearing between the mill table lead-screw and the universal dividing head.

Ian B
06-10-2012, 07:11 AM
Bytewise,

Really nice setup and end result, well done!

A question; if you had cut one gear of the pair as you did do, but cut the mating (second) gear using a gear cutter of the same diameter as the first gear, and then plunged the cutter centrally instead of milling along the teeth, would this produce a gear with curved teeth that give a larger contact area? A bit like a worm wheel.

Just a thought,

Ian

bytewise
06-10-2012, 09:27 AM
Ian, that is an interesting thought. It might be appropriate for the small gear of the unequal diameter pair. My application is fairly low torque an low speed so I think the small contact area between the gears should not be a problem.
Wayne, The calculations were all from the Machinery's Handbook section on Helical milling. The dividing head gears setup for different leads is detailed in the section on spiral milling. It is tricky and I spoiled a couple of blanks before I got everything right!!
Hugh

jep24601
06-10-2012, 09:33 AM
LOL! is it just me, or is the ratio still 1:1 even with the larger and smaller gear? Thats just crazy :)
Well, you get a constant mesh change of direction - the upper one with one way transmission (locking in reverse) and the lower one two way transmission. Presumably there's a reason.

1200rpm
06-10-2012, 09:43 AM
wow! nice job!
no, actually, GREAT JOB!!
i love seeing set-ups like this. it really makes you think!

Forestgnome
06-10-2012, 11:11 AM
That's awesome! I didn't know you could use the indexing in conjunction with spiral milling like that using the universal head. I'ld love to have that capability.

bytewise
06-10-2012, 11:25 AM
Yes, Jep, there is a reason. The large gear goes on the crankshaft and has to have a large bore. The small gear drives the cam and governor system and for clearance reasons it is preferred to be smaller diameter. The ratio must be 1:1. Hugh

Paul Alciatore
06-10-2012, 11:28 AM
First, that is an awesome setup. I am j_e_a_l ..... Very nice job.

I wonder which is the driver and which is the driven. If the larger gear is driving the smaller I see no problems at all. If the opposite, you may have to do some polishing and use a real slick lube. Specially if it is going to be running on exhibit 8-12 hours a day.


You need to store your pictures on a web hosting site like Photobucket. You then take the link under the picture, copy it and then paste it into your thread.
gbritnell

He did use Photobucket: just needs to copy and paste the links. Do read the instructions in the sticky post. Or just copy the ".img" code on the right side of the page and paste it into your posts. Instant pictures.

Wayne A Thackery
06-10-2012, 11:48 AM
Bytewise and Oldtiffie,

Thanks for the reply guy's! I will check my MH and go from there. Have made lots of spur gears over the years but no helical gears. Would like to give this a try for the fun of it...

WT

gbritnell
06-10-2012, 11:54 AM
Paul,
He edited his original post. In it he asked how to get the pictures into his post. I only answered what he asked.
gbritnell

Paul Alciatore
06-10-2012, 05:27 PM
Paul,
He edited his original post. In it he asked how to get the pictures into his post. I only answered what he asked.
gbritnell


Oh, OK. Paul A.

oldtiffie
06-11-2012, 03:45 AM
Bytewise,

Really nice setup and end result, well done!

A question; if you had cut one gear of the pair as you did do, but cut the mating (second) gear using a gear cutter of the same diameter as the first gear, and then plunged the cutter centrally instead of milling along the teeth, would this produce a gear with curved teeth that give a larger contact area? A bit like a worm wheel.

Just a thought,

Ian

The "plunged" gear would only be correct at its centre and the "worm-like" "ears" would "stand-proud" and interfere with the first/correct gear.

The gear has to be the same and correct along its full lenght.

"Free-wheeling" as has been detailed here recently will only work with a spiral-toothed "hob" (quite often from an acme thread). It will not work with a normal gear cutter.

http://bbs.homeshopmachinist.net/showthread.php?t=54672

Alfons Verheijden
01-04-2013, 01:04 PM
I can't help brag a little. Attached are pictures of some helical gears I made for a project. The large diameter gear has a helix angle of 63 deg. and cannot be cut in the conventional helical setup. The other pictures show the setup I used to cut that one. Link is http://s1258.photobucket.com/albums/hh587/bytewise

Dear Sir,
Once, I have read somewhere that you were looking after Doxford pictures to made a small model
Meanwhile I have pictures with measurments for making a 3-legged model, same as my avatar
If you are still interested please let me know
Kind Regards
Alfons