Tips to Avoid Wood-Splitting

[KregRep]

The number one suggestion is to make sure that you are using Kreg Screws.
Kreg screws have several features designed to limit, and even eliminate wood-splitting in your joints.
- The self-tapping tip drills the wood as it’s driven.
- The small diameter shank displaces less wood.
- The flat head doesn't wedge the wood apart when tightened down.
- The half-threaded shank eliminates binding.

Use Pan-Head Screws (SPS)
Our Pan-Head Screws have a smaller diameter that displaces less wood as it’s driven.

Use Fine-Thread in Hardwood
Coarse-threaded screws displace more wood with a more aggressive thread pattern.

Screw it In, Back it Out
By driving your screw half of the way in, back out, and then in again, you’ll reduce any excess wood in the hole.

Bee’s Wax
In extremely hard woods like Maple or Hickory, by applying some bee’s wax or other lubricant to the screw, you’ll reduce friction as the screw enters the workpiece.

Clamp, Clamp, Clamp
The primary benefit of clamping is to eliminate joint shift and reduce the need for sanding. Proper clamping also reduces workpiece movement, which can cause wood-splitting.

Test Pieces
Test your wood before you drill into it. Use a scrap piece that isn’t intended to be used on your final project.

Dry Wood Splits
It's important to understand what causes wood to split. In addition to certain species of wood being more prone to splitting, wood with low moisture is also more likely to split. If you live in a low-moisture location, your wood will be more prone to splitting and you’ll need to take extra precaution.

When All Else Fails, Pre-Drill
When you use your Kreg Jig®, pre-drilling your holes into the second workpiece isn’t required. However, in unique situations, with unique humidity levels, or uniquely split-prone wood, it might be your best bet! Warning: pre-drilling is not easy or recommended in almost any circumstance.

[William Brady]

Great tips and very helpful especially to a newbie like me in woodworking. Thanks!

[Ken Darga]

William,

Suggest making a copy of the topic, and file it with your Kreg Tools.

William Brady said:

Great tips and very helpful especially to a newbie like me in woodworking. Thanks!

[Etay Schnapp]

Hi,

I am attempting to make counter-tops from olive wood and using pocket holes to put together the olive wood planks... the wood is 0.5" stock (17mm) which makes it much harder to get a good joint done... the wood itself is extremely hard and cracks super easy which is even worse...

I have followed the list above very closely which helped much to minimize the splitting but still i get cracks when the screws drive to the joined piece... i make sure to clamp real well, i have pre-tested with scrap piece to see where the screw comes out and aligned another piece next to it to see the screw reaches about 1/8" below surface... also i am using 1" fine thread screws and driving them into the material slowly and in pulses (in 2 out 1) and still i get splits as the screw reaches the hole end... i am also dipping the screws in olive oil in order to add lubrication...

i should mention that without these steps i would crack the pieces every single time... with them a lot less, but still do i get splits here and there...

i have also ordered the 0.75" fine thread screws in hopes this will help prevent the issue, but they don't get a hold in the material... they just spin in place as they reach the end of the hole... (should i try to reset the stop collar 1/16" deeper than the 1/2" mark? this may help the 0.75" screws get more bite?)

lastly, i have resorted (as mentioned) to making a small pre-drill with a hand dremel after the pieces a clamped which basically eliminates the splitting completely...

any advice is much much appreciated!!

thx

etay

[Ed Rarick]

I assume you are using the standard #8 screws from Kreg.  I would try #6 screw.  When I have splitting problems (usually in cold, dry weather on hard wood) I switch to #6 screws and have no splitting.  Not everyone carries #6.  I get mine at Rockler and even they have limited selection.

I did an entire set of kitchen cabinets using Kreg along with several smaller projects.  I never have splitting problems on softwood and have not had problems on hardwood in warm months (I live in Minnesota). During my winter kitchen project I was splitting cherry face frames about 50% of the time, even when used a screw driver to tighten the single #8 screw I was using on face frame joints.  The second I switched to #6 sized screws all splitting disappeared. If you are using glue on your joints I see no problem using #6 vs. #8 Kreg screws.

[Etay Schnapp]

Hi Ed, thanks for the reply :)

I went to take a look, and in fact both the 1" and 0.75" fine thread (panhead) screws are #6 not #8... i don't know if kreg makes #8 ones for the 1" and 0.75", but one ones i ordered from amazon state they are #6...

http://www.amazon.com/Kreg-SPS-F075-500-0-75-Inch-Thread-500-Count/...

[Ed Rarick]

Wow, that is interesting.  If you are making a top can you just edge glue the planks?  You should not need screws for strength--the glue should suffice.

[Etay Schnapp]

I love my kregjig so much i honestly didn't consider just dropping it and using glue :) its much messier but i agree, if i can't get the splitting gone even with the 0.75" screws ill have to just glue it all together... i also considered trying the microjig? anyone can give feedback on that? are the pocket holes closer to the join or just smaller in size?

[Etay Schnapp]

OK, so I tried doing what I mentioned before, i.e. set the drill stop collar about 1/16" deeper than the 1/2" mark and use the 0.75" screws... with this setup i get a perfect join with no splitting almost 99% of the time!!! :D

[Jack Kelly]

I too am having a serious splitting problem! I'm using a bargain type of 19 mil Baltic birch for face frames.

I have set my K5 jig to the 5/8" setting in order to get the screws to come out at the center of the board which has helped some.

Changing the depth stop collar has had almost no effect.

I am running the screw half way in and out with no real improvement.  

I have yet to try lubricant, but I am also sure that this wood is very dry! 

My screws are genuine Kreg screws and I think that the length is correct for the application, any shorter and they would hold nothing.

Is pre drilling a realistic option?

Any comments or suggestions would be appreciated.

[Ed Rarick]

I would set the Kreg jig and bit collar normally and switch to #6 screws.  They are somewhat hard to find but they stopped my splitting of dry cherry -- which was a nightmare for me until I switched #6.  If you are working with face frames (mine are 1.5" wide) you only need one #6 screw in the middle of the frame as long as you also glue the joint.  The glue provides all the strength you need and the screw provides the instant clamping and flush alignment of the stile to the rail.

Just to let you know how bad my splitting problem was, my stiles would split even when I hand-tightened the Kreg screw vs. using a drill.  Just as the joint closed as I slowly turned the screw driver the wood would split -- EVERY TIME!  The second I switched to the #6 screws the problem went away and I have never has a split since.

[jim.zakany]

QuickScrews has what you want.

[Ken Darga]

Jack,

Baltic Birch is generally plywood.

Is the baltic birch you're using, contain several plys?

Installing screws in the glued section, can easily result in the plys separating.

When the screw enters, between the plys, the screw forces the plys to separate.

A pilot hole is necessary, to avoid this problem.

Make the face frames from solid wood.

Jack Kelly said:

I too am having a serious splitting problem! I'm using a bargain type of 19 mil Baltic birch for face frames.

I have set my K5 jig to the 5/8" setting in order to get the screws to come out at the center of the board which has helped some.

Changing the depth stop collar has had almost no effect.

I am running the screw half way in and out with no real improvement.  

I have yet to try lubricant, but I am also sure that this wood is very dry! 

My screws are genuine Kreg screws and I think that the length is correct for the application, any shorter and they would hold nothing.

Is pre drilling a realistic option?

Any comments or suggestions would be appreciated.