How to Locate the Center of a Hole With an Edge Finder

[ltlvt]

(05-17-2019, 01:22 AM)Highpower Wrote: Ahhh... OK. I totally misread what you wrote.  

In that case I would probably turn (or have someone else do it) an aluminum shaft to fit both original diameters (3/4 x 1.5). Make the larger diameter just wide enough to match the thickness of the casting on the back side. Make the smaller diameter long enough to protrude a bit from the hand wheel side to indicate off of. You should be able to find an unworn spot of the original hole to rest/clamp your shaft against to get the proper location/alignment unless the hole is really, really, REALLY wallowed out all the way around.  

Once you have the shaft dialed in for zero just cut the shaft in half (inside the carriage) so you can pull out the 3/4" end of the shaft and then bore away. Hopefully all the wear will be on just one side of the casting.  

Willie I have thought of doing that just as you have described. My fear is that the large hole for the plug could not be align bored with the shaft hole. You and Tom G have given me some excellent brain food to chew on. I may just use a combination of both. Thanks so very much for your help.

[ltlvt]

(05-17-2019, 08:58 AM)TomG Wrote: A method of finding the center distance between the two gears would be to mesh them on the bench and actually measure the distance directly, allowing a few extra thousandths for clearance. You could even make a test plate to mount the shafts, to verify the hole spacing before boring the hole in the apron.

The good news is that if you screw up the first attempt, it can be fixed by using a larger bushing.

TomG that is an excellent method. I will surely give that a try. Experience like yours and many others on this forum is what makes it a great place for a guy like me to learn. BTW I have watched most of your You Tube videos and learned a lot from you. I especially like the one where you made the wooden examples for sharpening tool bits for the lathe. That is the sign of a real mentor. Thanks for all you contribute to our machining communities. I managed our toolroom in our GM plant for many years but just recently got committed to my own little hobby shop with my very own PM 833-T bench mill. My main interest is resurrecting old machine tools like my 5913 Clausing and my Model 100 Clausing lathes. I have other resurrection projects but the 5913 is at the front of the list.  

Terry from Texas 

[TomG]

(05-17-2019, 11:26 AM)Highpower Wrote: I can see the clock maker in you coming out again Tom...    

The worlds first Clausing depthing tool...  

I'm not surprised that you would be the one to recognize where that technique came from. 

Tom

[TomG]

(05-17-2019, 01:21 PM)ltlvt Wrote:

(05-17-2019, 08:58 AM)TomG Wrote: A method of finding the center distance between the two gears would be to mesh them on the bench and actually measure the distance directly, allowing a few extra thousandths for clearance. You could even make a test plate to mount the shafts, to verify the hole spacing before boring the hole in the apron.

The good news is that if you screw up the first attempt, it can be fixed by using a larger bushing.

TomG that is an excellent method. I will surely give that a try. Experience like yours and many others on this forum is what makes it a great place for a guy like me to learn. BTW I have watched most of your You Tube videos and learned a lot from you. I especially like the one where you made the wooden examples for sharpening tool bits for the lathe. That is the sign of a real mentor. Thanks for all you contribute to our machining communities. I managed our toolroom in our GM plant for many years but just recently got committed to my own little hobby shop with my very own PM 833-T bench mill. My main interest is resurrecting old machine tools like my 5913 Clausing and my Model 100 Clausing lathes. I have other resurrection projects but the 5913 is at the front of the list.  

Terry from Texas 

Thanks Terry, it's always good to hear when the videos (and advice) are appreciated. 

Tom

[Dr Stan]

I've used this technique multiple times on larger (2+") holes with good success.  On smaller holes I prefer to use a plug/pin in the spindle that fits the hole or use a small center shaped like a bull center.  Depending on the accuracy required I'll sweep the hole with an indicator to get closer after using a center finder or a pin/plug.