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

[TomG]

Thanks Mick, glad you are enjoying the videos.

I have been thinking about doing a video on gauge blocks, so thanks for the reminder. It just so happens that I got stuck in traffic on the way home tonight so I had time (LOTS of time ) to plan it out, and I may actually shoot the video tonight.

Tom

[EdK]

(07-31-2013, 04:53 PM)TomG Wrote: Thanks Mick, glad you are enjoying the videos.

I have been thinking about doing a video on gauge blocks, so thanks for the reminder. It just so happens that I got stuck in traffic on the way home tonight so I had time (LOTS of time ) to plan it out, and I may actually shoot the video tonight.

Tom

[Micktoon]

Good news Tom ( not the traffic jam ! ) I look forward to seeing the video on the gauge blocks

Cheers Mick.

[marfaguy]

Sweet! Nicely explained and shown. Another good one Tom. Thanks.

[ltlvt]

Thanks Tom. I will be re -boreing the hole that my hand wheel shaft goes thru on the apron for my Clausing 5913. I plan to re-bore the casting and then bush  it with an oilite bushing. I am sure the hole will not be round since it was just cast iron against the shaft. I'm sure everyone with an old lathe knows of this problem with he hand wheel. Any thots of how to set this up on the mill. As we all know the shaft has a gear that must mesh with another gear inside the apron. Nothing better than learning from someone who has already had his experience.

[Highpower]

Use whatever you have on hand and your imagination to bolt the hand wheel down to the table and then bore your hole.

This is a hand wheel I needed to bore and machine driving dogs into it to use on the power feed for the knee on my mill. I have it bolted down to a rotary table/lathe chuck here to cut the dogs but you get the idea. If you only need to bore a hole just go straight on the table with it. If you need more clearance throw some 1-2-3 blocks under it.

   

[ltlvt]

Thanks Willie. I am not trying to bore the hand wheel I am trying to re bore the hole in the side of the apron . I have got a pretty good idea of how to clamp it to the table what I am asking is if the hole to be rebored is not round how should I go about finding the center. The opposite of the apron has a plug similar to a freeze plug in and engine block to remove the shaft from the back side. I will be taking that plug out in order to disassemble it. But that hole is about 1 1/2 " ID where the shaft itself is only about 3/4" diameter. Thanks again for the reply.
I will try to take some pictures tomorrow.

[Highpower]

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.

[TomG]

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.

[Highpower]

I can see the clock maker in you coming out again Tom...

The worlds first Clausing depthing tool...