Author Topic: Universal Joint (Read 8250 times)

Brian Rupnow · « **on:** November 21, 2016, 05:32:09 PM »

This is something that's been coming for a long time. Every model machinist, wants deep in his heart of hearts to make a universal joint. You have to reach a certain point of confidence in your ability to machine things and be bored enough to consider a project like this. The worst thing is that one universal by itself isn't much good. To really show them working properly, you need two of the darned things working together. I'm kind of dancing from one customer to another on small jobs with free time and wait periods in between spots of real work, so I think I'll try and make a couple of these.

crueby · « **Reply #1 on:** November 21, 2016, 05:39:48 PM »

And when you have a couple made, you will need to build the boat to put them in!

mklotz · « **Reply #2 on:** November 21, 2016, 06:07:32 PM »

The PM model milling machine has two tiny ones that use small brass balls as the pivot element...

John's diorama thread...

http://www.modelenginemaker.com/index.php/topic,4170.0.html

discusses their construction in detail.

Brian Rupnow · « **Reply #3 on:** November 21, 2016, 09:32:43 PM »

Thanks Marv, that is very cool. I hadn't seen that before.--Brian

Florian Eberhard · « **Reply #4 on:** November 21, 2016, 10:18:10 PM »

Hey Brian

If you are going to build universal joints - you may consider building a shay locomotive since they use them

(in a slightly different version though - I wonder why, probably because the ring around the two forks is more rugged than the cross??)

Cheers Florian

Brian Rupnow · « **Reply #5 on:** November 21, 2016, 10:29:31 PM »

Trains and boats don't really interest me too much. However, I'm getting so many little mechanisms built to run with my engines, that a driveshaft with two universals could connect my wonky 90 degree shaft transfer with one of the other machines.

crueby · « **Reply #6 on:** November 21, 2016, 10:48:36 PM »

Quote from: Florian Eberhard on November 21, 2016, 10:18:10 PM

Hey Brian

If you are going to build universal joints - you may consider building a shay locomotive since they use them
(in a slightly different version though - I wonder why, probably because the ring around the two forks is more rugged than the cross??)

Cheers Florian

Check my shay build thread for that style, works really well, telescopes. The real ones were huge, the ring over a foot across. Very sturdy style, they took full load of the engine.

Posts 498-515 here:
http://www.modelenginemaker.com/index.php/topic,3778.msg88528.html#msg88528

Brian Rupnow · « **Reply #7 on:** November 22, 2016, 04:18:49 AM »

I made a start today, then got busy with a bunch of "real work" and that eat up the rest of my day. At any rate, this is the drawing I'm working from, and this is how far I got on the part. Taken down from 1" stock to 0.890" diameter, taken down to 0.562 over part of the length, drilled and reamed as per drawing, and 60 degree taper machined in, all in the same set-up.

J.L. · « **Reply #8 on:** November 22, 2016, 12:40:03 PM »

Hi Brian,
Nice progress. Good luck with your design.
The B&S milling machine Marv mentioned uses 3/16" hardened steel ball bearings as their pivot points. Telescopic tubing also makes assembly of the forks quite easy.
John

wagnmkr · « **Reply #9 on:** November 22, 2016, 01:18:08 PM »

Hmmm ... I need some of these to go in this, so I will be following along.

Tom

crueby · « **Reply #10 on:** November 22, 2016, 03:58:26 PM »

Quote from: wagnmkr on November 22, 2016, 01:18:08 PM

Hmmm ... I need some of these to go in this, so I will be following along.

Tom

Nice hull! Dutch tugboat?

wagnmkr · « **Reply #11 on:** November 22, 2016, 04:31:34 PM »

Atlantic Salvor ex MrDarby.

Brian Rupnow · « **Reply #12 on:** November 22, 2016, 06:47:22 PM »

So here I am, making it up as I go along. I'm working with two bars of different material so I can judge which one seems to cut best with my machinery. The one in the vice is 1045 steel, and it machines relatively well. The other one is a piece of ground and polished A36, which is not hardened in any way. The A36 doesn't machine near as cleanly as the 1045--it tends to smear and tear rather than cut cleanly.

wagnmkr · « **Reply #13 on:** November 22, 2016, 08:30:20 PM »

Brian, I have found that 12L14 steel machines very well. My machines are smaller than yours and it works great in them and my Sherline.

Tom

Tennessee Whiskey · « **Reply #14 on:** November 22, 2016, 09:36:25 PM »

I'm following Brian, can't wait to see how you do the cups and needle bearings.

Cletus

Brian Rupnow · « **Reply #15 on:** November 22, 2016, 10:11:08 PM »

1144 and 12L14 are both very nice steels to machine. My machine doesn't mind the 1045 at all. I haven't got to the mill yet with the A36. Tennessee--there won't be any bearings in these universals. I am going to make the spider out of bronze. These are going to be "low mileage" universals. They will only see duty on my many different mechanisms that I drive with my engines.

Brian Rupnow · « **Reply #16 on:** November 22, 2016, 10:36:18 PM »

Here you can see an "in process" of cutting the centers out of the universal joint ends. I futzed around a bit just figuring out how I was going to do this, then drilled a 3/16" hole at each corner of what would be opened up and then just "chain plunged" with a 3/16" endmill all around between the holes, running at about 750 rpm taking 0.020" steps between full depth plunges. These are actually turning out too nice to free-hand the end radius. I may have to machine up a couple of filing buttons out of some 01 and harden it so I can make decent looking ends on the pieces.

Brian Rupnow · « **Reply #17 on:** November 23, 2016, 01:39:31 AM »

Well---that was a bummer!!! Turned up a nice filing button, heated it, quenched it---then tried it with a file and it cuts like butter. Some donkey put a stick of cold rolled in the drill rod rack. And since I'm the only person with access, well----However, I did find a piece of drill rod the right diameter after the fact, so that will be tomorrow mornings job.

crueby · « **Reply #18 on:** November 23, 2016, 02:01:31 AM »

Quote from: Brian Rupnow on November 23, 2016, 01:39:31 AM

Well---that was a bummer!!! Turned up a nice filing button, heated it, quenched it---then tried it with a file and it cuts like butter. Some donkey put a stick of cold rolled in the drill rod rack. And since I'm the only person with access, well----However, I did find a piece of drill rod the right diameter after the fact, so that will be tomorrow mornings job.

I'd blame the shop gnomes. Yeah, thats it, the gnomes...

Brian Rupnow · « **Reply #19 on:** November 23, 2016, 05:05:39 PM »

For anyone out there who doesn't fully grock the concept of "filing buttons" it is a rather neat trick. I wanted the radius on the tips of the universal where the 3/16" hole goes thru the arms to be nice and concentric to the hole. You could accomplish this with the proper set-up in a rotary table. You could (if you are very steady and keen of eye), do it freehand on a big belt sander. That is the way I do it most of the time on bigger parts. However, this trick is neat, I learned it of British steam engine web-sites. If you have a piece of drill rod the diameter of the finished end you want to put the radius on, then turn down an area small enough to fit thru the hole, then harden the drill rod by torch and quench method. I didn't bother cutting my drill rod down to a short length to make a "button"---I left it full length on the end of the rod. It doesn't matter. Put the part to be filed in your vice, insert the hardened drill rod, then start filing on the sharp corners of your piece. The file will only cut material until it gets down to the surface of the hardened drill rod, and won't go any farther, because the drill rod is now harder than the devils horn, and the file won't cut it. this leaves a very nice radius on the part you were filing.

Brian Rupnow · « **Reply #20 on:** November 23, 2016, 05:57:46 PM »

Now I'm at a juncture---I was going to finish all the ends first, then do the center spiders.--but--This looks so exciting I can't wait. I have to make the spider now and finish this first universal joint.

mklotz · « **Reply #21 on:** November 23, 2016, 06:17:20 PM »

Hey Brian, here's something that can employ your universals

https://s3-us-west-1.amazonaws.com/hmt-forum/gears_with_direction_change.gif

Brian Rupnow · « **Reply #22 on:** November 23, 2016, 06:43:42 PM »

Yes Marv. I've seen that before. That is very close to being a set of mangle gears. Be a bit tough to build in metal though, I think.

Brian Rupnow · « **Reply #23 on:** November 23, 2016, 08:33:28 PM »

The spider is finished, and it turned out really good. There was a nifty trick used in machining that. The material is 3/8" thick. I cut out the profile on my bandsaw, leaving just enough material for cleanup. I cleaned up the 4 cut sides on my beltsander, and cleaned up the 4 notches in the corners of what started out as a rectangular piece of bronze with a file. Set it up in the mill vice and reamed one 3/16" diameter hole thru, then turned it 90 degrees and put the second 3/16" hole thru. Now comes the trick part. 3/16" is 0.188". The outer diameter of a #10 bolt is 0.190" in diameter. A bolt that size will "self thread" thru brass or bronze, cutting a very shallow thread. I tapped a #10-24 thread in the end of a piece of round 5/16" diameter cold rolled while it was set up in the lathe 3 jaw chuck. The socket head bolt goes thru the bronze part and screw into the end of the 5/16" diameter cold rolled steel rod. Then, using a 3/32" cut off tool, and the o.d. of the steel rod as a reference diameter (that is the diameter of the bosses on the spider) I took cuts in .030" increments from the face of the spider closest to the chuck, until the newly cut boss reached the length I desired. Did that 4 times. ran the 3/16 reamer thru each hole once more, and it was finished.

Brian Rupnow · « **Reply #24 on:** November 23, 2016, 09:52:57 PM »

And there it is finished, in one of it's potential new homes. I coat the inside of the bronze spider with good quality grease, tap the pre-cut to length pieces of 3/16" cold rolled shaft almost home (one is a single piece which goes all the way thru everything, two of the pieces are shorter and just butt up against the long one at the center of the spider), and coat the last 1/16" with 638 Loctite before tapping them all down flush with the outside of the universal joint body.

Perry · « **Reply #25 on:** November 23, 2016, 10:19:10 PM »

Helo Brian, in one of the photos above I see you are using what looks like an ordinary drill chuck to hold the endmill. Do you have good experience with that combo?
Regards
Perry

Brian Rupnow · « **Reply #26 on:** November 24, 2016, 12:04:07 AM »

Perry--I do. That is an old battle that I have fought many times. Would I do it with a full size Bridgeport that was being used on a production basis?--No. Would I do it side milling steel under high loads with big endmills?--again, no. With smaller endmills and working with aluminum I do it all the time. If milling steel with anything bigger than a 3/8" endmill I use an endmill holder. Remember, I work almost exclusively in the world of model engineering. On a small scale you can get away with a lot of things that you couldn't get away with doing on big full size machines in a production environment.

wagnmkr · « **Reply #27 on:** November 24, 2016, 01:18:16 PM »

Congrats Brian ... that looks the part and I am sure it will be quite strong as well. A bit large for what I need, but I am going to re-scale it and have a go.

Do you have any snow up there yet? I need to get up to the metal toy store one day soon.

Tom

Brian Rupnow · « **Reply #28 on:** November 24, 2016, 01:51:51 PM »

HiTom---we've got about 2" of snow on the ground. I don't think it will stay. The weather guys are calling for rain later in the week.

wagnmkr · « **Reply #29 on:** November 24, 2016, 02:10:35 PM »

Thanks Brian ... about the same as us then. We also have the forecast for rain and freezing rain.

Tom

Brian Rupnow · « **Reply #30 on:** November 24, 2016, 06:42:23 PM »

As I get a bit deeper into the machining of the second universal, using the A36 material, I'm not seeing a lot of difference in how it machines compared to the 1045 material. Possibly a bit more drag on an endmill when I'm backing out of a plunge cut, but not a big enough difference to worry about. I think that overall, there isn't a big enough difference in machinability between the two different materials to worry about.

Brian Rupnow · « **Reply #31 on:** November 25, 2016, 12:42:29 AM »

I left one picture out of the line-up when I was making the first universal joint. This is a picture of the four 3/16" holes that were put in just before "chain plunging" the material away from 3 sides with a 3/16" endmill .

Brian Rupnow · « **Reply #32 on:** November 25, 2016, 12:47:52 AM »

Almost there!! If I can get the spider for the second u-joint done tomorrow, I'll have a pair of them. It's crazy--this is a $650 pair of u-joints, if you consider the time that went into them at about $40 an hour for cheap machine shop rates. I can remember buying full sized auto u-joints for about $16 a set.---Says a lot for the economies in automation and mass production.

Brian Rupnow · « **Reply #33 on:** November 25, 2016, 07:17:08 PM »

And we're finished. Two more toys to add to my stable of "weird things I can run with my model engines". It has been a quick and painless build, and it's just another of the nifty things I wanted to build---Just to see if I could!!

<a href="https://www.youtube.com/watch?v=Ci9783NXzr0" target="_blank">http://www.youtube.com/watch?v=Ci9783NXzr0</a>

strictlybusiness1 · « **Reply #34 on:** November 25, 2016, 08:47:03 PM »

Brian,

For many years I have made ball & pin type constant velocity universal joints. They are used at RPM's of 30,000+ & 7.0+ HP. All the parts are made of AISI-O1 tool steel. The slotted female part is fully hardened in the area where the drive pin rides. The drive pins are M-2 steel blanks & they are pressed into the male ball parts. The male ball parts are fully hardened & then tempered to a spring temper.

Jim Allen

News:

Author Topic: Universal Joint (Read 8250 times)