Screws that don't strip

[Jeff]

Measure the root diameter of your lag screws or wood screws to help determine the pilot hole size which can be a bit larger in hardwoods and a bit smaller in softwoods.

[FONT=&quot]Solved with larger predrill and lots of bee's wax and the 20 volt impact.[/FONT]

There's also a down side to impact drivers. I have 2, 1 is a 12 volt and the other is a 20 volt. When I was building my new work bench I was driving 3/8 inch X 6 inch lag bolts into oak. I was predrilling. The 20 volt with it's extra power was twisting the bolts into at about 5 to 5-1/2 inches left to go. The 12 volt would not even start to move the bolt. Solved with larger predrill and lots of bee's wax and the 20 volt impact.

Pop

 

[DSWalker]

The issue you are experiencing is often referred to as "cam out" if you should wish to research the topic any further (at least aside from that hands-on research experience you have already acquired).

Both Phillips and traditional straight bladed screw heads are very prone to cam out just by way of their design (in the case of Phillips it was intentional to prevent overtorquing the screw or bolt), hence a big part of the reason that alternatives like Torx, Pozi-drive, Robertson (square), hex/Allen head, etc., have all been created and marketed over the years for higher torque applications. Also be aware that these days many screws that look like Phillips are actually JIS (Japanese) standard (and increasingly Pozi-drive as well, but Pozi-drive can be easily recognized by the much smaller wings in between the four major wings forming a nearly square center opening) and using a normal Phillips bit in these screws will result in one cramming out very easily, chewing up the face of the screw. You can recognize JIS screwdrivers by a flat (in the smaller sizes) at the tip where a Phillips comes to a much sharper point by comparison. But the JIS/Phillips confusion results in a lot of headaches because using Philips screwdrivers in JIS screws leads to a rather poor fit prone to cam out when you try to apply much torque due to the deeper point of the Phillips driver, and because the two look so similar superficially we tend to mix up both the screws and their drivers in our parts and toolboxes without realizing such. You can generally count on getting away with using a JIS screwdriver in place of a Phillips when mating to a Phillips screw, but not the other way around since a Phillips driver can not fully mate with a JIS screw.

However, when you need to apply enough torque to risk cam out you also have another option besides the "lowly" screwdriver and that is using an electric (usually cordless) impact driver. Impact drivers can deliver a great deal more torque without cramming out because they utilize a high impulse hammering action that exploits the inertia provided by the tool's own weight and only rotates a short distance on each strike (further reducing the risk of cam out since the but can reseat between strikes). Additionally, they avoid the usual torquing against the user that one experiences when using a typical drill/driver or cordless screwdriver -- so much so that they can be comfortably used one handed even in high torque applications.

Hope this also helps to shed some light on the topic as I know it can be quite frustrating.

This is very informative. I had no idea there were different types of drivers that looked like Phillips.

 

[Pop Golden]

​Thanks Jeff. The best way to measure a screw pilot hole is to hold it up to the light with the drill bit in front and see how much thread is showing. Also if it's hard wood, drill out the top of the hole for the unthreaded part of the screw to give it a place to go so you're not trying to force it into the pilot hole. I used soap for years before I discovered wax. I used old candles for years before a fellow woodworker gave me a hunk of bee's wax. It's the best screw lube I've found yet

Pop :eusa_danc

 

[DSWalker]

David,
What are you using the screws for and what is the failure method (sounds like camout - stripping out the drive)
What drive style are you using / do you want to use?
Can you use an alternate drive style? (torx / star / six lobe - all different names for the same thing) the bit engagement is better and you have less cam-out problems.
or is the screw body breaking when you install the screw (s)

This particular application is for a bench made of white oak, attaching the seat to the base. Screws are camming out. Had another that actually broke inside the base.

 

[tarheelz]

We've made it to Post #25 and no one has mentioned my favorite? SPAX Screws? (German company that has US manufacturing.)

http://www.spax.us/

While you can find some of these at the BORG, the online selection and pricing is much better.

I keep these (mostly in yellow zinc) "unidrive" screws in stock in sizes 1/2" to 2": http://www.spax.us/en/multi-material-construction-screws/unidrive-flat-head.html

With unidrive, you can use Phillips, Robertson, or the combo bit.

Edit: Grainger has Spax screws on clearance right now!

 

[Tarhead]

We've made it to post #26 and no one has mentioned worn driver bits. In my experience the bit is usually the problem, not the screw. Bits don't last forever and when they start to wear they slip and don't grab the screw like they should.

 

[Gotcha6]

I'll have to add one caveat on a specialty screw one may use. I had an application that required stainless steel #2 square drive screws going into pressure treated wood. Stainless screws are very soft compared to other screws and do not hold up well to impact driver forces. Best to use a slow speed drill or a regular screw gun for these.

 

[Pop Golden]

Hi Dennis, Having never used them I always thought stainless steel screws were harder than standard screws. This is good info.

Pop

 

[Gotcha6]

They may have a higher tensile strength, but I don't believe they are tempered like other screws. The ones I used would fail before getting completely seated without using a traditional drill, and they were #2 square drives as I mentioned. I tried variations on the square drive bits too but to no avail.

 

[tdukes]

Been using the star/torx screws for a while with a 1/4" impact driver. Can find them in #6, #8 and deck screw sizes at Lowes. I'm not using 1000's of these at a time so 5 or 6 bucks not killing me.

 

[JimD]

I usually use my little Ryobi 1/4 impact driver to drive screws partially to avoid cam out and partially because it's lighter than my cordless drills. Mostly I just use drywall screws. I know they are brittle but I am usually using them as a clamp to hold two pieces together until the glue sets up. I like many of the other suggested screws too but most of the time I don't need anything better than a drywall screw.

If you google around long enough you can find a site where they quote test results for screw holding power as a function of the pilot hole size. I don't remember the results too well, which vary by wood species, but 50% of the screw diameter for softwood and 70% for hardwood seems about right. With a big enough pilot hole, you will not break the screw and it is obviously easy to drive. You might pull the threads out of the wood. But if you have that problem you can use a drill and set the clutch or learn how long to beat on it with the impact.

 

[Rwe2156]

This particular application is for a bench made of white oak, attaching the seat to the base. Screws are camming out. Had another that actually broke inside the base.

Don't be so quick to blame it on the screws. If screws are camming out breaking off, your pilot hole it is probably too small.

An impact is not going to help, either.

If you're using a tapered drill bit, be sure you're using the right size.

Ise a little bees was or paraffin on the threads helps a lot.

That being said, I do despise the star bits and much prefer square drive.

Somebody mentioned Spax - I use them but hate them because of the wobble factor. Try screwing them into something off a 10 foot ladder. Bring your magnet cause you'll be picking up the ones that fall off the bit .....

GRX are better (and more expensive) than Spax.

Square drives are great because they stick to the bit.

 

[Gotcha6]

"Square drives are great because they stick to the bit."

Not always. We purchased 2- 50# boxes of square drive screws for a project some years ago that were prime coated. On 30% of them the screw heads had so much paint in them the bit wouldn't go in the socket far enough to hold to the screw. We had to discard the whole box. Buy good screws, and buy good bits. Replace the bits regularly. I'd rather replace a bit as to have a screw head strip out.....

 

[Hmerkle]

There is a lot of information here - and some "real-world" experience.

While there are "cheap" screws at the BORG's usually you can make them work.
As Jeff and Dr. Bob mention; the pilot hole (and clearance hole) are VERY important.

If you can't drive the screw by hand - you WILL have trouble with a drill driver.

Cam-out happens because the torque required to turn the screw is high and the operator cannot put sufficient "end-force" on the driver to keep the bit engaged in the drive.
Ethan mentioned in his post that a cross recess (Phillips) is prone to cam-out due to the angular design of the drive, BUT if you can put sufficient end force a quality bit WILL stay engaged and not cam-out of the drive!

This relies on a well executed pilot hole and shoulder hole as either of these can increase the torque required to drive the screw and as a result require more end-load to keep the bit engaged in the drive.

The square drive does have "bit-stick" meaning you can put the screw on the drive bit and hold it horizontally.

You can purchase Phillips ACR bits. While you will not get "bit stick" the "ribs" or "fins" on the driver bits help keep the bit engaged.

Also, if you can find true "Torx" bits rather than "Star" or "Six lobe" drives the "user experience" is better. you can hold a torx screw horizontally on a bit, not so sure about a "Star" or "Six lobe" screw.

Many people don't know that Phillips was a monumental change - the Phillips drive stayed engaged much better than a slotted drive - yep a marked change in 1932!

Not definitive info, but from my teaching pretty accurate;
https://en.wikipedia.org/wiki/Henry_F._Phillips

It is always a great laugh when I am teaching and mention that the screw was designed in 1932, but the driver was created a year later in 1933!!:BangHead:

 

[JimD]

Matthias W??, the woodworking for engineers website and youtubes, tested drywall screws for holding power versus deck screws and a normal woodscrew. He got equal or greater holding power and not bad ductility. I like it because I don't think drywall screws are a bad alternative for most projects. In softwood, I drill no pilot hole but do drill a clearance hole so it will pull the pieces together better. But in hardwood, I usually do not use screws but if I did, I would drill a pilot hole. Usually. But when I did the handrail to newel post connections for stairs (both oak), I used trim head screws and did not drill pilot holes. The screws were supposed to take care of that themselves and did. I think I used 2.5 inch screws. I got them at the home center, I think the heads were spanx. They were noticably better screws than my normal drywall screws.

 

[LeftyTom]

Hi Dennis, Having never used them I always thought stainless steel screws were harder than standard screws. This is good info.

Pop

I used stainless steel screws when putting up my composite deck. If I tried "no pilot hole", the screws would twist from the heat. I contacted the manufacturer, Swann, about the issue, and they sent me a pound of stainless screws free.

 

[CrealBilly]

We've made it to Post #25 and no one has mentioned my favorite? SPAX Screws? (German company that has US manufacturing.)

http://www.spax.us/

While you can find some of these at the BORG, the online selection and pricing is much better.

I keep these (mostly in yellow zinc) "unidrive" screws in stock in sizes 1/2" to 2": http://www.spax.us/en/multi-material-construction-screws/unidrive-flat-head.html

With unidrive, you can use Phillips, Robertson, or the combo bit.

Edit: Grainger has Spax screws on clearance right now!

I like to buy local Menards carries Spax their the best I've found locally. I totally avoid anything metal made in China, Screws, nails,. blades, drills, bits, etc... To many problems in the past so I avoid now if I can. Lucky for me Menards carries a lot of stuff tool wise made in USA.

 

[Leviblue]

Second for Mcfeelys. They used to have a gripper type Phillips head that was great. Hard to cam out the drive slot. The square drive works very good as well. The assortment sale was a great price when they have them.