DP table lock improvement

[pop-pop]

This is the OE table lock on my pricey Nova drill press. Its limited leverage proved too hard for my aging hands to reliably lock the table.

My first try was this wooden handwheel which did lock the table easily. However, it basically was only usable with my left hand from the front of the DP and it gave no hint when I forgot to tighten it.

My latest try is this lever cam that I made:

The DP table is unlocked when the lever is horizontal. Just a few pounds of force on the handle in any direction will securely lock the table. Here I raised it upward:

And at a glance I can tell if the table is locked.

Construction began with this scrap of 1/8"x2" steel angle (I would have use Al but didn't have anything suitable).

Sawn into two pieces with a Diablo steel cutting blade on my table saw.

In this pattern, the rise of the two cam surfaces is 1/16". This dimension came from eyeball engineering and was spot on.

The pair were drilled together. I use an extra drill press (bought from @Dreuxgrad whilst he was in Durham) with a cross slide vise for metal work.

Final shaping done on a 1x30 using those excellent blue belts from Klingspor.

Trial assembly before handle was shaped. Pivot is a 3/16" spring pin and threads are a M-12 coarse thread bolt beheaded.

 

[drw]

Mike, once again you have proven to be very inventive...your creations are always functional and ergonomically designed!

 

[pop-pop]

Thanks, Donn. As a bonus, it's enjoyable for an old guy!

It's also per force since my grip has waned with age.

 

[Gofor]

 

[Wiley's Woodworks]

Mike--I'm not that far behind you in age. I can live with the fact of life that we lose muscle strength as we age, but the one I miss the most is my grip strength.

 

[mpeele]

Mike is that a 2" radius on the business end? I think I'm going to do the same thing.

 

[pop-pop]

Mike is that a 2" radius on the business end? I think I'm going to do the same thing.

It’s not one radius but two mirrored. Think of it as two tilted arcs The tilt forms a ramp that gives the clamping force.

Turned out that explaining how to do this using a drawing was not easy. I have been thinking on explaining how to lay it out using photos and will work on it tomorrow. It is actually easy to do but hard to explain. Should only take a day or two and I will post.

BTW, it really works well.

 

[mpeele]

It’s not one radius but two mirrored. Think of it as two tilted arcs The tilt forms a ramp that gives the clamping force.

Turned out that explaining how to do this using a drawing was not easy. I have been thinking on explaining how to lay it out using photos and will work on it tomorrow. It is actually easy to do but hard to explain. Should only take a day or two and I will post.

BTW, it really works well.

So it's not an eccentric. Radius with mounting point offset by 1/16" towards the end of the handle but a spiral or elliptical

 

[pop-pop]

So it's not an eccentric. Radius with mounting point offset by 1/16" towards the end of the handle but a spiral or elliptical

Arc thru 3 points.

It is a radius but its center is offset from the pivot. I have the cartoon figured out and will post later today.

 

[pop-pop]

Michael, here is the cartoon showing the geometry for the cam end. I'll post later how to lay it out on the stock.

 

[pop-pop]

I had a scrap of 1" wide Al and here is how to lay out the cam surfaces referring to the diagram in the previous post.

First. cut two pieces to length and fasten together with double-sided tape. I coated one surface with red layout dye and scribed a line along the longitudinal center.

Then scribe a line across spaced X (not Y) from the bottom. Next is a scribe across 1/16" from the bottpm. Center punch these two intersections (they will be Y apart).

Next, scribe 45 degree lines from the pivot point in each direction downward (lines will meet the corners).

Along each 45 degree line, mark Z distance from the pivot point and center punch.

Lastly use a circle template or equivalent to scribe a circular arc through each set of three points.

The upper arc is being scribed here. Note that the previously scribed lower arc does NOT make a semi-circle with the upper arc. BTW, the radius of each arc turns out to be Z.

Hopefully this will help anyone who wants to make this DP table clamping lever.

 

[pop-pop]

Made a locking lever for my metal working DP. This time I used 1/4” x 1” Al bar stock from Ace Hardware for the eccentric cams.

Here is the cam end up close.

 

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I have been pleased with how convenient these cam locks have turned out to be.