search for expanding lathe arbors

I am planning on making a arbor as follows. First swap to a four jaw chuck and then center drill both end of a piece of one inch round stock about a
foot long. Then chuck up a piece of round stock about three inches in dia anb about four inches long. Drill and bore a hole to fit the one inch roun d stock and also cut a 60 degree taper on the outside so the small end of the taper is a bit urnder 2 inches . And repeat for another matching piece . And make two retaining rings about !.5 inches in diameter and with a one inch hole with at least one set screw.
The reason for doing this is to bore a fairly well centered hole on some ca st gears. After boring the hole in the gear so it is a machined surface in stead of a cast surface, mount it on the arbor and rotate it to see how wil l centered the hole is. Bore it out some more trying to get the hole cent ered and mount on the arbor and repeat until the hole is pretty close to be ing centered. The gears are pretty nicely cast, but do have surface fluctu ations so it is hard to figure out where to measure from. The gears are b evel gears which does not make it easier. Put a 1/2 inch diameter rod betw een two teeth and it tended to wobble.
Anyway while thinking about this, I remembered some arbors I had seen with a more gentle taper , but made with slots in the tapers so that one taper c ould go in the slots of the other taper and one would have a large range o f adjustment. Tried searching on MSC and Ebay , but can not think of a goo d search term. Does anyone know what this type of arbor is called?
And it anyone has a better idea of how to bore out a cast iron bevel gear so the hole is well centered, please comment on that too. The gear will be turning at maybe 100 rpm so perfect is not needed, but it would be nice t o have the run out to be less than a 1/16th of an inch.
Dan
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On Fri, 31 Jan 2014 19:16:15 -0800 (PST), " snipped-for-privacy@krl.org"

http://www.use-enco.com/CGI/INPDFF?PMPAGEI4&PARTPG=INLMK3&PMITEMB2-1674
cheap screw solution to locate off bore: Clamp bar stock in chuck. Turn to size. Drill and tap taper pipe thread in end. Leave bar in chuck to minimize run out. cross cut end of bar with hack saw and debur. taper pipe plug will expand arbor enough to hold gear when torqued.
to locate of teeth faces use a plate with a taper hole matching the taper of the bevel gear and three dowel pins to locate off the teeth faces. Clamp the plate to the face plate, bore the tapered hole with compound and leave attached for minimum run out, clamp the gear in the hole using dowel pins to locate off tooth faces. Bore hole to size, then use expanding arbor to machine gear as required. http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKAC5-0044&PMPXNO”517
Let the group know what works!
--
Unka' George

"Gold is the money of kings,
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On Saturday, February 1, 2014 2:56:33 AM UTC-5, F. George McDuffee wr

422-1674

That is a good way to make an arbor to hold a part for machining. But in m y case I want an arbor so a part can be rotated and any out of round can be seen. And I would like it to be useful for bores from a bit under 2 inche s to bores of three or four inches.
On the current gear being worked on, the bore is now a bit over two inches . The final bore might be as much as 2 15/16 ths. So almost an inch bigge r.

O”517--

This might be useful, but I hesitate to use a plate with a tapered hole to hold the dowels. The little gear is a bit over a foot in diameter. The l arger gear is more than two feet in diameter. So maybe use bungee cord to pull the pins into the gear faces. The problem is that the dowels do not f it snuggly, but may be good enough for a reference. Currently the thinkin g is to use the gear teeth as cast. We do not have a mill big enough to ma chine the teeth of the larger gear and I am not sure if the mill is big eno ugh for the smaller gear.
Dan
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On Sat, 1 Feb 2014 09:24:48 -0800 (PST), " snipped-for-privacy@krl.org"

==================Given these are bevel gears, the best bet for a gear face locator pin might be a round magnet. http://www.allmagnetics.com/alnicorods.htm
Given the size of the parts relative to the machines, some of the old time machining books will have some hints. railroad and ship machining would be a good place to start.
One old time "arbor" kluge is a "cats head" mandrel https://www.google.com/search?q Êt%27s+head+mandrel+lathe&num0&lr&newwindow=1&hl=en&as_qdr=all&tbm=isch&imgil=iDP7ZmYwpSCxRM%253A%253Bhttps%253A%252F%252Fencrypted-tbn3.gstatic.com%252Fimages%253Fq%253Dtbn%253AANd9GcQJhznv_KtDxSTohoNEjdg6dvV4q8yFaHmOUgeIYNpbIbrKOZfU%253B1024%253B768%253Byys7M_eQIZQnHM%253Bhttps%25253A%25252F%25252Fwww.ar15.com%25252Farchive%25252Ftopic.html%25253Fb%2525253D6%25252526f%2525253D49%25252526t%2525253D377360&source=iu&usg=__qc9x6yfae4KREI7paR902dvgQU4%3D&sa=X&ei=uG3tUrj-MOr7yAH74YHoDw&ved DYQ9QEwAw&biw07&bihP2#facrc=_&imgdii=_&imgrc=iDP7ZmYwpSCxRM%253A%3Byys7M_eQIZQnHM%3Bhttp%253A%252F%252Fwww.practicalmachinist.com%252Fvb%252Fattachments%252Ff24%252F41804d1324771678-new-taiwanese-gunsmithing-lathe-finally-here-p1000979.jpg%3Bhttps%253A%252F%252Fwww.ar15.com%252Farchive%252Ftopic.html%253Fb%253D6%2526f%253D49%2526t%253D377360%3B1024%3B768 This is not the cat's head that goes over irregular barstock, e.g. hex, so it can run in a steady rest, but is a mandrel with 2 sets of stout hex head screws set at 120 (or 90) degree angles that can grip the inside of bore. [Most likely 3 at 120 is better as this gives more room to swing the wrench to adjust the rear set] By adjusting the screws the workpiece can be tilted and offset relative to the mandrel. I've never used one, and they look to be a real PITA to adjust, but would seem to do what you want, and should be relatively cheap/easy to make.
Lindsey Books had many reprints, but is no longer in business. http://www.lindsaybks.com/ Your Old Time Book Store bought most of his inventory. Their website is http://www.youroldtimebookstore.com/category-s/2075.htm
try http://www.youroldtimebookstore.com/category-s/1967.htm
also see https://archive.org/details/textbookofadvanc00smituoft https://archive.org/details/textbookofelemen00smitrich https://archive.org/details/practicalmetalt00horngoog
sounds more interesting all the time. be sure to let us know how things work out.
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Unka' George

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I have trouble imagining this.
Say you have a ring cut from flat plate, somewhat smaller than the gear OD. You drill the ring for as many parallel, evenly spaced , axial dowel pins as the gear has teeth. When you place the ring upside down onto the gear so each pin fits between two teeth, does the plate automatically fall parallel to the base of the gear's pitch line cone, so that you could mount the gear on a rotary table and indicate the ring to level and center the gear?
I think it does, and you need only 3 or 4 dowel pins.instead of the full set.
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I'd probably chuck up a piece of scrap and machine a countersink in it that's the same angle as the bevel and clamp it into the conical recess with a washer that's been bored out enough to let the hub stick out and that's held to the other piece with three screws. .
If you want it to be REALLY acurate, you can use 3 dowell pins, appropriately sized to pick up on the involute instead of the major, (hold them to the gear teeth with stick wax while you're tightening the fixture washer)
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