Mating 1 ½" to 1" problem

[Guy Fisher]

Hello,

I needed to mate a 1 ½" main workpiece (the one to be drilled) with at 1" mating workpiece in a 90° attachment.

Using the various charts available online like https://www.dropbox.com/s/jvl0rf4kbwz4jrh/Kreg%20-%20Pocket%20Screw... or https://industrydiy.com/woodworking/kregtools/kreg-jig-settings-chart/ 

I set the jig and drill bit to 1 ⅜" and used 2" long screws (see attachment). Luckily I did a test fit and saw that the screws were around ⅛" too long, would have gone through to the other side of the mating workpiece.

So I used 1 ½" screws which seemed to be perfect.

Did I read the chart wrongly?

Any advice would be appreciated.

Thank you.

[Mike Hensel]

Hello Guy

It appears you did everything as advised on Kreg pdf. Is it possible your clutch setting was set too high. You were wise to do a test before actually assembling. I would hate to have that surprise if it were me.

Mike

[Guy Fisher]

Hello,

Clutch setting was set pretty low. On my Makita drill/driver it was set to setting 4 out of 16. But even if it was too high, it would merely strip the mating workpiece, due to the embedded washer in the screw head, the screw would never be able to make the screw head go below the bottom of the pocket hole.

It seems that 1 1" ¾ screw would have worked but Kreg doesn't make screws in that length, but I'd rather have the screw a little too short than too long and penetrating to the other side of the mating workpiece.

See photos of the settings of drill bit collar and jig height setting and screw penetration measurements for 1" ½ and 2" screws. 

I think Kreg chart had a typo, it needed a 1" ½ screw.

[Mike Hensel]

Good info. I am going to make a note of this on chart I down loaded. I would hate to mess up an expensive pc. of wood  over to long of screw.

Mike

[Guy Fisher]

I think I'll create an iPhone app to calculate the measurement below so that using various "non standard" size lumber, anyone using the jig and this app can verify screw clearance and penatration:

Pd - Penetration Depth

Pc - Penetration Clearance

Sc - Screw Tip Clearance

Sd - Screw Tip Depth

Hd1/2 - Hole Depth

Hb - Hole Bottom

Ht - Hole Top

[Michael A. Mitra]

try using the pan head screws. I believe that's what their dsigne for