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 round 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 cast gears. After boring the hole in the gear so it is a machined surface instead of a cast surface, mount it on the arbor and rotate it to see how will centered the hole is. Bore it out some more trying to get the hole centered and mount on the arbor and repeat until the hole is pretty close to being centered. The gears are pretty nicely cast, but do have surface fluctuations so it is hard to figure out where to measure from. The gears are bevel gears which does not make it easier. Put a 1/2 inch diameter rod between 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 could go in the slots of the other taper and one would have a large range of adjustment. Tried searching on MSC and Ebay , but can not think of a good 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 to have the run out to be less than a 1/16th of an inch.

Dan

On Fri, 31 Jan 2014 19:16:15 -0800 (PST), "
wrote:


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 round 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 cast gears. After boring the hole in the gear so it is a machined surface instead of a cast surface, mount it on the arbor and rotate it to see how will centered the hole is. Bore it out some more trying to get the hole centered and mount on the arbor and repeat until the hole is pretty close to being centered. The gears are pretty nicely cast, but do have surface fluctuations so it is hard to figure out where to measure from. The gears are bevel gears which does not make it easier. Put a 1/2 inch diameter rod between 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 could go in the slots of the other taper and one would have a large range of adjustment. Tried searching on MSC and Ebay , but can not think of a good 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 to have the run out to be less than a 1/16th of an inch.

Dan

http://www.use-enco.com/CGI/INPDFF?P...MITEM=422-1674

cheap screw solution to locate off bo 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?P...4&PMPXNO=94517

Let the group know what works!


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"

On Saturday, February 1, 2014 2:56:33 AM UTC-5, F. George McDuffee wr


http://www.use-enco.com/CGI/INPDFF?P...MITEM=422-1674



cheap screw solution to locate off bo 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.


That is a good way to make an arbor to hold a part for machining. But in my 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 inches 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 bigger.

wrote in message
...

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.

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)

"F. George McDuffee" wrote in
message ...

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?P...4&PMPXNO=94517

Unka' George

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.

On Sat, 1 Feb 2014 09:24:48 -0800 (PST), "
wrote:

On Saturday, February 1, 2014 2:56:33 AM UTC-5, F. George McDuffee wr


http://www.use-enco.com/CGI/INPDFF?P...MITEM=422-1674



cheap screw solution to locate off bo 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.


That is a good way to make an arbor to hold a part for machining. But in my 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 inches 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 bigger.




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?P...PMPXNO=94517--

Unka' George


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 larger 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 fit snuggly, but may be good enough for a reference. Currently the thinking is to use the gear teeth as cast. We do not have a mill big enough to machine the teeth of the larger gear and I am not sure if the mill is big enough for the smaller gear.

Dan
====================

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=cat%...0%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.


--
Unka' George

"Gold is the money of kings,
silver is the money of gentlemen,
barter is the money of peasants,
but debt is the money of slaves"

-Norm Franz, "Money and Wealth in the New Millenium"