My try at a better center finder

[Dale Allen]

I need to know if there is interest in this before I do much of a writeup.
Since I now prefer to turn my pen blanks round before drilling, I struggle with this task. The tools I have purchased for this do not work well enough for me so I have made something different.
This is a piece of modeling plastic cut to 1" square and about 7" long.
I have created a 90 degree pocket in 2 pieces about 2" long with a pin extending from the top that is directly over where the corner of the blank would be.
With the corner pieces set on opposite corners, I hold a small steel ruler up against the pins and mark the center by drawing a short line in both directions.
This works on those blanks that are not precisely square and that may have a ragged edge. I took a picture of a marked blank and drew lines in a drawing program over the corners. It appears to work rather well.
At least now I do not need to bother making the blank square before marking the center. I will test one of the marked blanks tomorrow by drilling center bit holes in the end and turning it down part way.
I'm sure some refinement ideas are out there among the group. Let me know what you think and if this can be improved on, I'm all ears...or eyes! :biggrin:

 

[Mack C.]

I need to know if there is interest in this before I do much of a writeup.

Seems like a lot of work to me when these are already available from cnccutter, a member here. They work like a charm as well!
http://www.penturners.org/forum/f157/thumb-square%A9-stocking-stuffers-104466/

 

[SteveG]

You might try what I do, with great success (NO square or jig involved). Hold the blank in one hand in position to draw on the end. Hold a pencil in the other hand with the tip extended just enough to strike a line approx across the center of the blank, line to be parallel to one side. Your middle finger fingernail of the hand holding the pencil needs to ride against the face of the blank as your reference as you strike a line across the end of the blank. At this point, DO NOT change your grip on the pencil. Rotate the blank to strike 3 more lines, each referenced from a different side of the blank. The resultant four lines will very accurately indicate the center of the blank. this also works on slightly irregular and on rectangular shaped blanks. Play with the technique and you will find it works on cylindrical blanks also. Very quick, and no need to keep track of your specialty blank CL square or jig.

 

[its_virgil]

Except for some blanks such as segmented blanks and maybe a few others, knowing the exact center and halving perfectly square blanks is not necessary. "Close" works fine. Go for it. Making new tools is fun and there will be several who will find it necessary and will have to have one.
Do a good turn daily!
Don

 

[Lenny]

I made this with some scrap pieces of aluminum angle and a couple cuts on the miter saw. Epoxy worked well to hold it together.

 

[Dale Allen]

Lenny; I have made similar things.
The problem with that one and the thumb square is that they do not work on stock that is not perfectly square.
Mine has a relief cut on the inside corner and will accurately mark corner to corner on even a slightly rectangle piece.

I guess my need is unusual and this is not something that would be of interest! :redface:

 

[Lenny]

I understand your wanting precision, it is a good goal!

In use I have found that even irregular blanks, by rotating it 4 times and scratching a mark, will result in a very easily determined ceter point. As Don mentioned, in most cases, close is Close enough.

 

[CharlesJohnson]

Hi Dale. I don't think I really understand that relief cut. Thanks.

 

[Dale Allen]

Charles, if you place the corner of a wood blank into the inside corner of say an angle iron, it does not go completely into the corner. It may look like it but the fact is that you cannot get the inside corner to a perfect point, it will still be a bit rounded.
The relief cut is a way to allow wood to not have to press into that inside corner.
It is the same principle as a center drill bit. In that case the tip of the lathe center is allowed room so as not to be pressing into the very tight point.
The relief cut above also allows a corner that is slightly less than 90 degrees to fit into the fixture with the sides still touching.

 

[Dale Allen]

I understand your wanting precision, it is a good goal!

In use I have found that even irregular blanks, by rotating it 4 times and scratching a mark, will result in a very easily determined ceter point. As Don mentioned, in most cases, close is Close enough.

Have you ever had a pen kit that would look really good with a certain blank you had but was not sure the blank was big enough?
If the blank is 5/8" square and the largest OD on the pen is going to be .5", that doesn't leave much room for error when drilling. I can use that blank if I can find the exact center and turn it round, then drill it out dead center.

 

[Mike D]

I made one like Lenny's a couple of months back. It's cheap and works very well as opposed to the one sold by Woodpeckers that is much more expensive. I think Lenny posted his and I made mine from that post. I applied alodine to mine.

 

[Lenny]

One of the advantages of turning to round to drill on the lathe is once rounded you know the max diameter you have to work with.
If your blank is really crooked and your looking to maintain the maximum diameter it might be beneficial to cut the blank in half and turn each half individually. Either way the center marking gauge will quickly find the center of even uneven blanks ... The marks don't have to all intersect in the same point to be effective.