Method for clocking rectangular or square in a four jaw to a known reference point

[thehomeengineer]

Hi All

Method for clocking a four jaw to a known reference point or datum. I use this technique for clocking rectangular or square stock in the four-jaw chuck. It is extremely accurate and it saves messing with toolmakers buttons, per drilling or any other means and less accurate ways such as clocking over the corners of the stock.

I mainly use it for getting square bar concentric, but yesterday it dawned on me I could take it one-step further and locate a known datum or reference point on the work piece.

It does not show it on the video but after machining the hole and counter-bore, I check the component for accuracy and it was within 0.001” in both directions.

I hope you find it a useful video and thank you for taking the time to view
The Home Engineer

[DIYer]

Thanks thehomeengineer! We've added your Square and Rectangular Stock Clocking Method to our Measuring and Marking category,
as well as to your builder page: thehomeengineer's Homemade Tools. Your receipt:

Square and Rectangular Stock Clocking Method by thehomeengineer

tags: chuck, dial indicator, measurement, centering

[Ralphxyz]

Thanks, I am just starting to use a four jaw chuck so this really helps.

Ralph

[mklotz]

Hi All

Method for clocking a four jaw to a known reference point or datum. I use this technique for clocking rectangular or square stock in the four-jaw chuck. It is extremely accurate and it saves messing with toolmakers buttons, per drilling or any other means and less accurate ways such as clocking over the corners of the stock.

I mainly use it for getting square bar concentric, but yesterday it dawned on me I could take it one-step further and locate a known datum or reference point on the work piece.

It does not show it on the video but after machining the hole and counter-bore, I check the component for accuracy and it was within 0.001” in both directions.

Since you've already done the measured layout of the point to be centered on the stock, why, in effect, reproduce that measurement procedure with the stock mounted on the lathe?

Wouldn't it be simpler to use a pump center in the marked out dimple and adjust the chuck using that?

For reference, the procedure for doing so is outlined here...

http://www.homemadetools.net/forum/c...aw-chuck-27241

[thehomeengineer]

Hi Marv
Thank you for your interest. The lines are for reference and I could have done it the way you suggested. As you can appreciate, there is more than one to skin a cat.
I thought about doing the job firstly on the mill hence the spot drilling on the faces. There was an issue with that. As it had a flat bottom counter bore and I wanted a tight fit on the mating part I decided, it would be a lot easier to machine in the lathe.
Normally I use this method to centre square bar in the four-jaw chuck, so it is perfectly concentric to each stock face This method is so accurate every time so I used it for this operation and it came out spot on.
Thank you again and I hope I have answered your question
The Home Engineer