Author Topic: Chris's Build of Steering Engine  (Read 14077 times)

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #120 on: September 27, 2022, 06:47:30 PM »
I think you did the worm gear perfectly. It was a nice demonstration of how to make it. For a one-off production, it's totally okay. I like it very much.

Michael
Thanks Michael!

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #121 on: September 28, 2022, 04:02:23 AM »
Michael, another question for you. I was looking at the pictures again, and have decided to nickle plate the gears and the engine bed and vertical wall plates, since there will be places where the steel would show around bearings, posts, etc, and the brass would not look right. While going through the pictures for that, I noticed this little fitting under where the steering wheels are:

What is the fitting pointed at by the red arrow?


Thanks!
Chris

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #122 on: September 28, 2022, 08:24:40 AM »
Hi Chris, this is a hook to lock the large steering wheel.
I suspect that there was an eyelet or hole somewhere in the steering wheel to hook into.
There is one more detail on the small gear. There is a hole to put oil on the shaft inside.

Michael

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #123 on: September 28, 2022, 08:29:59 AM »
I think I mentioned before that this sheet metal plate with the eight screws supports a fracture of the casting. You really don't need to rebuild it.

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #124 on: September 28, 2022, 02:05:40 PM »
Great details - that oil hole is interesting, makes sense that it needed a way to oil the inner shaft bearing. Thanks!

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #125 on: September 28, 2022, 04:29:05 PM »
Continued on the larger spur gear today. The OD was turned down to size and the blank taken to thickness on the lathe with the riser blocks in:

Since its such a large diameter, a set screw near the hub was drilled/tapped through the blank and into the arbor. This is in a spot where it will be cut out for the spokes later so it wont show. It will ensure the blank doesn't turn on the arbor, especially when milling in the spokes which can put force on it to the side.


The mill didn't have quite enough travel to put the blank far enough out to clear the gear cutters, so I had to drill/tap a few new holes in the tooling plate to let the rotary table sit farther out. The M1.75 cutters are a much larger OD than the smaller module cutters I had been using, plus this is a large gear (over 4.1") .

Off to lunch with some friends, might start cutting gear teeth this afternoon, may wait till tomorrow...

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #126 on: September 28, 2022, 09:27:33 PM »
For those who use (or want to use) a rotary table with handwheel to cut gears, keep reading. For all others, including those who use a dividing head with the hole plates or some other setup on their machine, you can skip the rest of this post.

On my machine, a Sherline mill, I use the rotary table to cut gears. Their rotab has a handwheel that turns the table 5 degrees per full handwheel turn, and its marked in 10 major ticks (one per degree) and each of those in 10 more minor ticks (tenths of a degree). To cut gears that have a number of teeth that evenly divides into 360 degrees, thats an easy bit of math to do to determine how many full and partial turns to do per tooth. But, that seems to happen very rarely - more often (like the one I am cutting now) there are some oddball number like 58 teeth, which works out to 6.20689655 degrees per tooth, which is hard to work with!

So, several years ago I made up a handy little spreadsheet to do the math and take care of remembering all those digits of precision and rounding for me (Don also has some great spreadsheets, I started with one of his originally). The spreadsheet got tweaked along the way to make it easier for me to use, as I learned more of the little tricks in Excel and did more models with gears and also a number of clocks with LOTS of gears.

The attached file is where that spreadsheet stands at present. It has two fields to be entered - the number of whole degrees per full turn of the handwheel (I have it set to 5 since thats what I have on my mill), and also the number of teeth in the gear you want to cut. It then spits out a table of moves, first telling you how many full turns to make on each tooth, then a number telling you what handwheel tick to stop on. I set it to display one decimal point on the tick to stop at - even though the handwheel is marked in one degree ticks, its not hard to visually guestimate partial degrees on that scale, and if you are off a fraction of a degree thats usually close enough for what we do.

Here is a screenshot of what the spreadsheet looks like - it goes off the screen, but this example shows all thats needed:

The two yellow boxes are what need to be filled in. One time, set the first one to number of degrees per handwheel at the top, save it again, and you can leave that one alone till you buy a different rotary table.

The second box is the number of teeth in the gear you want to cut, and hit enter or tab. The numbers in the rest of the sheet will update for that gear. In this case, I put in 11 teeth. It gives the stats on the gear first, then there is a table. For this gear, there are 32.7272727 degrees per tooth - an unwieldy number if trying to do this manually, but the computer does all the work.

The table shows to do 6 full turns of the handwheel, then stop on the next number. Start with the handwheel set to the 0 position, cut the first tooth, then turn 6 times and stop at the '27' tick plus .3 more of a tick. Cut that tooth. Then 6 more full turns FROM THAT POSITION, and stop at 4.5 ticks. And so on. Always do the number of turns from where you are, not from 0. For gears with lots of teeth, that full turn number may be 0, so just go from tick number to tick number.

Another key thing - as each move is made and tooth is cut, check off that position so you can keep track of where you are! I learned the hard way early on that without marking it down, I would goof and skip a number or do one twice, ruining the gear. I always print out the chart I am making a gear from, and check things off as I go.


In the example, notice that down on line 20 the box is green with a 0.0 in it. That is where the pattern repeats. There are many cases where the number of teeth will be multiples of the number of entries before the green line. In those cases, make the passes down to the green line, then go back up to the starting 0 and repeat till the gear is done. If you have the spreadsheet downloaded and open, put in 32 teeth in the box, hit enter, and you will see the pattern is '2 full turns then,' followed by the sequence 0.0, 12.5, 25.0, 37.5, then the green line. So, for that gear, you would repeat the same sequence every four cuts.

Now, I've gone through the spreadsheet and believe that I have it all working for rotary tables with degrees/handwheel turn other than 5, but its always possible I missed something - if you find a goof, PLEASE let me know and I'll fix and repost it.

Hope this comes in handy for someone, it has been a huge use for me.

Chris
 :cheers: :cheers:

Offline ozzie46

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Re: Chris's Build of Steering Engine
« Reply #127 on: September 28, 2022, 10:59:52 PM »
Great job Chris.
My rotary table has a 90 to 1 worm ratio, how does that work in your program?

Ron

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Re: Chris's Build of Steering Engine
« Reply #128 on: September 28, 2022, 11:40:16 PM »
Great job Chris.
My rotary table has a 90 to 1 worm ratio, how does that work in your program?

Ron
If it has a handwheel with a scale on it, how many degrees does it turn the table with one turn of the handwheel?  If no handwheel like that, my spreadsheet does not apply. A 90 to one would be 4 degrees per turn I think. In that case, put '4' in the first yellow box in the spreadsheet and it should work.


Its intended for something like this:
https://www.sherline.com/product/3700-4-rotary-table/#description

Offline ozzie46

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Re: Chris's Build of Steering Engine
« Reply #129 on: September 29, 2022, 11:45:49 AM »
ok, thnks. I'll chk hand wheel today.

Ron

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Re: Chris's Build of Steering Engine
« Reply #130 on: September 29, 2022, 04:53:01 PM »
Continuing on with the gear cutting, the large spur gear is now cut:

and as mentioned in the previous post, I had the rotary table moves printed out and checked them off as I went:

The gears so far:

Next up is the small spur gear. This one goes on the outer shaft at the top, inside this shaft is another one that drives the upper worm gear from the sterring wheel. Started with prepping the blank - it has a larger inside bore than the others to fit over the outer shaft:

It was mounted on an arbor, and the teeth cut in it.


The cutter also cut into the arbor, no getting around that since the bore is so large and a thin arbor would have been too weak.

The finished small spur gear. The wall thickness at the bore is pretty small, though it will be soldered to the outer shaft which will strengthen it. I'm wondering if I should remake it as part of that outer shaft...   :thinking:

And the obligatory family shot of parts so far:

Next steps will either to remake that small spur gear as part of the shaft, which wont take very long, or go ahead to start cutting the spokes in the larger two gears...  Good place to go get some lunch and ponder that.
Won't be much progress over the next several days, got another big event happening this weekend so no shop time after today till Tuesday. Thanks for watching along!
Chris

Online cnr6400

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Re: Chris's Build of Steering Engine
« Reply #131 on: September 29, 2022, 05:23:23 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Online crueby

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Re: Chris's Build of Steering Engine
« Reply #132 on: September 29, 2022, 06:54:17 PM »
After lunch decided to go ahead and remake that one small gear integral to the shaft it sits on, it will be much stronger this way. Turned up a longer blank, which was used as its own arbor. Being narrower and sticking out from the chuck, I set up the tail end support for it too.

Cut in the gears like before

Here is the fut gear. It will get a half-lap cut on the short end, that will engage with the control nut on the smaller worm gear later.


And an updated family shot, with the first attempt at the small gear exiled to the upper right corner   :Lol:


Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #133 on: September 29, 2022, 07:01:08 PM »
Hello Chris, I thought you glued the small gear onto a shaft. But of course that's how it works. This shaft in particular is a complicated part. I'm still excited.

Michael

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Re: Chris's Build of Steering Engine
« Reply #134 on: September 29, 2022, 07:55:24 PM »
Yes, the gear has to be able to be driven by the engine through the larger gear underneath, while the inner shaft and the small worm gear on it get driven by the smaller of the steering wheels. So the outer shaft has to be able to turn seperately from the inner one.