Kreg K3 Jig Hole Misalignment???

[MikeL]

Greetings fellow members! I cut my first pocket holes today using the Kreg K3 jig, and I have a question concerning my results. I am using 1/2 MDF (I know I may be asking too much of this jig with the material choice and size) to box a portion of a new mantle shelf. I set the jig up according to the directions for 1/2" thick material, but the exit holes of the final product do not exit along the center of the edge of the boards. The result was having the 1" screws bust through, albeit narrowly, the exterior side of my 90 degree joint. :BangHead:

Has anyone had any issue with the drilling angle when using thin material? I used the base unit after securing it to a piece of 3/4" plywood that was clamped to my work surface. I took my time and made sure the pieces sat flush with the base when clamping them into the jig. The MDF measures a full 1/2". I drilled 16 holes, each having the same result. My apologies for not supplying photos. Maybe someone can make sense of my description. :icon_scra Any help would be greatly appreciated.

 

[junquecol]

Did you adjust the height for use with 1/2" materials. Some Kreg jigs use a spacer, and others adjust the height of the drilling block. I can't remember which your jig uses.

 

[Sully]

The first time I used mine I didn't realize that I had to set both the drill bit depth with the stop collar and also adjust the height of the guide block. When I forgot to adjust the height of the guide block, the result was exactly what you describe. Also, you have to use the correct length screws.

If none of the above is at play, then I'm out of suggestions. Hope you get it figured out.
J

Edit: Looks like me and Bruce were thinking the same thing.

 

[MikeL]

Yeah, I adjusted the block height for 1/2" material. The brass knob threads into the top whole for that setting. Since you use those pre-drilled holes, I don't know how I could fine tune it.

 

[Glennbear]

I have not used my jig on 1/2" material but I have had problems from blow through on MDF when I over tightened the screws when doing a 90 degree joint. I am definitely not a Kreg expert despite the sign visible in my avatar so YMMV. :gar-La;

 

[MikeL]

I'll recheck that setting, but I am fairly certain that the top setting on the block was to be used for 1/2" material.

 

[Sully]

drill bit depth set?

correct length screws?

 

[MikeL]

Glenn, I was thinking that the MDF might be the culprit. However, just looking at the bottom edge of the board (before screwing it to the other board), I can see that the holes are not exactly centered. Since I am using 1/2" material, that little bit of difference appears to make a big deal.

 

[MikeL]

Jay, maybe it is the drill bit depth. I used the guide that is made into the base and aligned the shoulder of the bit next to the 1/2" line. Tomorrow I will try to back of a bit and see if that helps. That may do it. It's the inly variable that I can really adjust.

I am using 1" screws. According to the chart, that's the recommendation.

Thanks for the questions!

 

[ehpoole]

IMHO, 1/2" material in general is really at the limit of the standard K3 guide block. Kreg makes another (black) mini guide block that is more geared towards the thinner 1/2"-5/8" materials which uses a narrower bit and a shorter screw (3/4" for 1/2" material) and also better conceal the screw (much as the standard block conceals the screw nicely in 3/4" material)

That said, I'm not really comfortable that Kreg screws (or pocket holes) are most appropriate for 1/2" MDF (and other particle composites) -- especially for carcasses or structural components; they may be fine for attaching a decorative and non-structural face frame, though. They can be Ok in 3/4" if not subjected to alot of abuse (use the 1-1/4" Hi-Lo Screw for MDF)-- it's just really easy to split the untempered MDF edge when working so close to the edge.

If you are making butt joints (and if you are using the Kreg you almost certainly are) there is a far better fastening system for composite materials like particle board and MDF. They are known as Confirmat screws and are available in two standard sizes, the smaller (5mmX40mm) is for 1/2" material and the larger (7mmX50mm) is for 3/4" material. They are specially engineered for composite particle materials and function very much like a steel dowel joining two pieces together while also allowing for knock-down disassembly if so desired. The hole for a Confirmat screw must be made with a specially stepped bit which cuts all the proper shoulders to their proper depths for the Confirmat screw -- which is much easier to duplicate with the proper drill bit. You will also want to use a Pozi Bit (#2 for 1/2", #3 for 3/4") to screw them in (all of which are included in the starter kit below).

The Confirmat screws will allow you to build a really strong carcass, much more so than pocket screws in MDF or particle board. The only downside is that they are not naturally concealed (though I imagine one could make MDF plugs and use them to help conceal the fastener).

The above kit includes 100 5x40mm Confirmat screws,
100 white screw caps, stepped drill bit with
spare bit and a #2 Pozi screwdriver bit.​

PS - I, too, love the K3 Master Kit (Heck, I even have anywhere from 500 to several thousand of each screw style and size) and use mine for many jobs -- especially for quick-and-dirty solutions. It's just that, in my admittedly limited experience, 1/2" MDF is a poor material choice for this system because untempered MDF edges can split so very easily -- and do so undetected -- that it is hard to guarantee a strong joint with pocket hole joinery. By comparison, this is precisely the reason the Confirmat screw above was engineered in the first place.​

HTH​

 

[Rob]

Mike, I've had my depth stop slip on me after several holes drilled, be sure it's tight.

 

[Joe Scharle]

If the block is set to 1/2" and the bit stop is also set to 1/2", the hole should be correctly bored.
I've made jigs with 1/2" MDF and my experience was:
1. Don't count on the screws alone...glue the joints.
2. MDF will pucker when a screw tries to penetrate. So I drill the pocket holes until I get a hole just breaking out of the edge.
3. Use coarse thread, washer head screws. I usually drive the screws with an impact driver, but NOT on MDF. I use a driver/drill clutched so that the last full turn is with a hand driver.

Just my experience.YMMV!

 

[Weber]

My Kreg jig is about 15 years old and does not have an adjustment capability on the jig itself. I just back off the depth setting on the bit until I get the correct amount screw penetration. Essentially, all I am doing is raising the level at which the screw pan bottoms out.

 

[MikeL]

Thanks Larry. I am headed out to give this a try.

 

[tryingtokeepmyfingers]

I thought you needed this if you were going to use 1/2 material ?

http://www.amazon.com/Kreg-KJMICROD...UTF8&coliid=IZ35PFA0DMSQR&colid=3JXXTEMHQ528V

since I thought the K3 was built for 3/4 or greater but I could be wrong

 

[Asheville Hardware]

I agree with ehpoole, that the 1/2" material is cutting it close on the standard Kreg system. With the softness of the MDF, it may just be as simple as torquing the screws too far. The tolerances in depth in material that thin are pretty tight, so it doesn't take much to sink the screws too far. I would highly recommend the Micro Pocket guide for thinner stock.

I just checked on our Kreg jig here in the store. If you put the drill bit into the jig, with everything set for 1/2", the tip of the the bit should be 1/16" away from the bottom. Just for reference.

Scott

 

[CaptnA]

Just wondering...
Did you measure the thickness of the material? It may be sold as 1/2" but is it really?

You did. Read over that the first time.

 

[Asheville Hardware]

Just wondering...
Did you measure the thickness of the material? It may be sold as 1/2" but is it really?

MDF usually runs exactly at what it says it is, at least as far as I've seen.

 

[McRabbet]

If the screw tip is penetrating the work piece, then the hole is too deep or you may be over-torquing the screw with your drill and the screw head is getting embedded too deep. I would recommend that you lower the drill stop to make a slightly shallower hole and reduce the torque setting on your drill. Another trick would be to add a small washer that will clear the outer diameter but keep the screw head from "sinking in" to the MDF. Like Joe Scharle has suggested, you should apply glue to these joints.

 

[KenOfCary]

I used my K3 jig today to secure some 1/2" plywood to some 1/2" plywood with no problems. I can see how MDF might be trickier. The Confirmat screws mentioned earlier are definitely the way to go with MDF, but as mentioned aren't concealed like the pocket holes.