Author Topic: Chris's Build of Steering Engine  (Read 17183 times)

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #90 on: September 25, 2022, 01:53:49 PM »
Reminds me of Harald‘s video: ce8-WFwaI70
That is a great video!  One thing he does differently that how I did my test one was to plunge cut the involute cutter in to pre-cut the teeth, rather than run the cutter across the face like I did, as on a normal tooth. That would give a larger contact area in the final gear, and allowed him to precut deeper into the blank. I'll have to look at doing that on mine, and see if it makes much difference on the smaller gear sizes I am making.
Thanks!!

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #91 on: September 25, 2022, 05:03:57 PM »
This morning did more on the gear cutting test. Now, I know full well that the engineers downtown at Gleason Works, where they make state of the art gear making machines of all types, would laugh themsleves silly at this setup, it is good enough for what I need to do for this one model! I'll send the shop elves down there to roll the crew back into the building later...

To start, I needed to set up the rotary table on a 6.5 degree angle for pre-cutting the teeth with an involute cutter, M1.75, Nbr 8 from the set, which judging by eye will clear out the bulk of the tooth spacing but not do for the final cuts. The back of the rotary table base was raised up on strips to get the angle, and the back screws to the mill table were swapped with longer ones. Then the gear was cut to 36 teeth, to a depth of .107" which is shallower than the cutters would normally be used at, but that depth gets it down to where the Acme teeth would end. Also, the diameter of the blank was calculated for the acme teeth, not the involute teeth. The blank is 2.25" diameter, which works out 0.040" small for the 36 tooth worm sput gear, but its close enough to test out the process, and 36 tooth spacing on the rotab is two full tuns of the handwheel, better for a quick test like this.


Then, the spacers were removed and the rotary table base set back down flat - a key step!!  The involute cutter was swapped for the acme screw hob I made yesterday, and the table moved over to center the blank on the hob. In this picture you can see that I cut the teeth like the video Horst posted showed, plunge cutting them rather than doing the normal sweep across the width. Thanks for that Horst!


Another key step is to change the cap on the arbor from this position, which clamps the blank tight to the arbor:

to this position, with the undercut on the cap facing out, to let the blank spin freely on the arbor. The shaft and arbor sides were oiled to aid in the spinning, and keep the blank from galling on the arbor. I also put a pen mark on the blank so I could easily see the rotations.


Then ran the mill table inwards till the teeth on the blank engaged with the hob, and turned on the mill at a slow speed. The table was moved in farther till it started to cut, and every several revolutions of the blank the table was moved in another few thou. That continued, with the mill speed being turned up as the cutter got fully engaged. Partway through I noticed it was bogging down, and I saw that the sides of the teeth on the hob were binding a bit behind the cutting face. I took the hob out, and did some more relieving on the teeth, which got it working much better again. More slow advancing, and it got down close to where the final depth wanted to be. A little more cutting needed, but it was time for a lunch break!

I held up a piece of the Acme rod to see how it is looking, and it is very close to done

The sides of the blank outside of the threded rod will be tapered back on the final gear, that is why the blank is so wide.

So, some more cutting after lunch, and I think it will be ready to taper the sides, I want to see how that will look compared to the gear on the real engine. May not get to that this afternoon, we have our first RC boat run at the Y pool this afternoon.
 :cheers: :cheers:

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #92 on: September 25, 2022, 05:48:11 PM »
After lunch took the gear down the rest of the depth, Looking pretty good. As I mentioned, the blank was .040" under sized so the tips of the teeth are slightly low. For the real gear, I think I may start with the blank a little tall and let the cutter form the hollow in the center more. Then I took it over to the lathe, and tapered in the sides like the real engine has:

The 'finished' test gear.


This was successful enough that I am now confident in doing the full size gear, well worth the test run. This gear will sit on the shelf for now, it will likely find its way into some future project. Till then the shop elves can turn it into a table or something!
 :cheers: 

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #93 on: September 25, 2022, 05:56:20 PM »
Michael - a question for you on the original engines. The pictures of yours shows fancy spokes on the worm spur gear, but I just noticed that the pictures of the other engine from the ship show just a flat plate between the rim and the hub, with bolts holding it to a rim on the hub. Do you know if that was just a difference from one machine to the next, or was one of those gears a replacement? I like the spoked version a lot better.



Offline cnr6400

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Re: Chris's Build of Steering Engine
« Reply #94 on: September 25, 2022, 06:09:28 PM »
The test gear looks great! congrats on a successful op.  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

The hob looks to be cutting well. Have fun with the boats today!
"I've cut that stock three times, and it's still too short!"

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #95 on: September 25, 2022, 07:27:19 PM »
Hello Chris, you recognized that correctly. The gear wheel with spokes is still the original gear wheel from 1897.
The gear wheel without spokes is a spare part. Some machines were so badly worn that even cylinders were rebuilt. Everything on our steering machine is still original. Only the pistons have been renewed after the new drilling. Coincidentally on a diameter to fit piston rings of truck engines.
I discovered and enlarged the gear wheel with shaft on a photo in the corner.

Michael

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #96 on: September 25, 2022, 09:28:48 PM »
Michael, good to know!




CNR, great time with the submarines, they had just cleaned the pool and changed the water, so fewer dissolved salts and chlorine, best radio reception, I was diving to the bottom of the deep end.   :whoohoo:

Offline cnr6400

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Re: Chris's Build of Steering Engine
« Reply #97 on: September 26, 2022, 12:22:06 AM »
Great Chris! glad it was good sailing conditions and reception. The shop elves didn't show up with depth charges this time, I take it?  :Lol:
"I've cut that stock three times, and it's still too short!"

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #98 on: September 26, 2022, 01:19:48 AM »
Great Chris! glad it was good sailing conditions and reception. The shop elves didn't show up with depth charges this time, I take it?  :Lol:


Stop giving them ideas!   :hammerbash:

Offline cnr6400

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Re: Chris's Build of Steering Engine
« Reply #99 on: September 26, 2022, 01:36:13 PM »
I keep forgetting they read this forum!  :facepalm: :Lol:
"I've cut that stock three times, and it's still too short!"

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #100 on: September 26, 2022, 06:23:49 PM »
Today I'm starting on the real worm wheel for the steering engine!  This one meshes with the same Acme screw thread as the test one, but this one is the full diameter, so it had to be cut from a piece of 3" wide flat bar. The blank was sawn out on the bandsaw, and the corners knocked off so it would spin on the lathe without needing to put in the riser blocks. It JUST fit in the mill vise to drill/ream the center hole:

Then it was set up on an arbor like before, to round off the outside and take it down to the finished diameter of 2.8". It was also faced on both sides to get it down to the finished thickness of .588", outside the nub left in the center where it clamps to the arbor.


That got it small enough to hold in the 3-jaw chuck and trim off those nubs

Then, as before, the rotary table on the vertical stand had to be tipped up 6.5 degrees to get ready to pre-cut the teeth. This time there are 43 teeth, and the precut was done with a M1.75 involute cutter, using the #8 cutter from the set (the one for 135->infinity teeth). The teeth were cut in .126", which took the bottom of the cut down to the desired tooth depth and root diameter for the worm gear. The 2.8" OD left room to take the depth down below the OD of the blank, which leaves the desired arc on the surface.

Tipping it up required putting some longer screws at the back of the base plate so they could still reach the t-nuts in the mill table.
Then the cutter was installed and the height adjusted to be in the center of the gear, and the table moved left/right to put the cutter in the center of the side face. These adjustments were a little trickier than when the rotary table was in its normal vertical position, where the center could be determined easily by the center of the screw head on the arbor. It was done by eye looking down the back side of the blank. Then cuting started, using plunge cuts in the center of the blank rather than the usual passes down the side.

Here is the finished set of pre-cuts.

You can see how the plunge cuts make a different tooth shape than the normal passes - the tops of the teeth are narrow in the center. Also, note the cap under the screw on the arbor, the cup shaped side is towards the blank, to hold it securely. For the next steps, that cap was reversed to put the flat side in, so the gear could spin freely since the center post in the arbor is several thou longer than the thickness of the blank. The center post and side faces of the arbor were oiled to reduce friction. The hob was installed in the drill chuck, and a line drawn on the side of the gear to make it easy to see when it has made several revolutions at each depth. The mill table was adjusted to put the hob in the center of the gear, both up/down and left/right.
Most important at this stage, the blocks under the back of the rotary table base were removed to put the rotary table back to its normal vertical position again! It was raised so the pre-cut slots would line up with the worm gear hob.


Ready to start cutting...

In this next sequence I'll try and show how the hob changes the shape of the teeth. Tough to get good pics on the shiny surfaces. Here is the teeth as pre-cut:

After the initial slow speed cuts with the hob - the mill table was fed in a few thou every few turns of the gear blank. First cuts were at slower speed to let things get started. You can see the semi-circular shapes being cut into the sides of the teeth.


and much more so after more cutting, increasing speed on the cutter but keeping the feed rate slow. At this point the center of the tooth tops are getting cut into by the bottom of the hob teeth shapes.


At that point I stopped once in a while to back out the table and find the point where it would turn freely. That setting on the handwheel was compared to the starting position to determine the mesh depth of the two gears. Here it is when it was down to the desired depth:

At this point the hobbing operation was done, and next time I'll go back to the lathe to start shaping in the sides of the gear. Quite happy with how this has turned out, thanks again to those who helped me learn this cutting method!   :cheers:   This size gear was not available anyplace I could find ready made gears, and anything even close was very expensive.


Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #101 on: September 26, 2022, 06:38:02 PM »
Chris, that looks very good at first.
And if the gear is still machined on the sides, it will look even better.
I think you also want to make the gear wheel with spokes.

Michael

Offline cnr6400

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Re: Chris's Build of Steering Engine
« Reply #102 on: September 26, 2022, 07:34:53 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn: :cheers:
"I've cut that stock three times, and it's still too short!"

Offline RReid

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Re: Chris's Build of Steering Engine
« Reply #103 on: September 26, 2022, 08:40:59 PM »
Been busy and just skimming through posts lately. I'm going to have to go back and go through this gear cutting method more thoroughly later, it looks like an interesting method, and the results look really good. :ThumbsUp:
Regards,
Ron

Online Admiral_dk

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Re: Chris's Build of Steering Engine
« Reply #104 on: September 26, 2022, 08:46:46 PM »
Difficult to take the pictures - oh Yes - but still - the Pre-Cut Gear looks nothing short of Amazing  :praise2:
It is harder to get a good idea about the finished item, with all it's facets - but you are Happy and that is what matters most (I most likely would be too)  :cartwheel:  :cheers:

Per