Spax Screws

Page 1 of 2  
Do these things really work? I'm interested in knowing whether I could drive them through the face of 1/2" plywood into the edge of 3/4" plywood without splitting. (Assuming I'm reasonably near to the middle of the edge.)
JP
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've done that. I like Spax screws. Of course you do have to use the right size. A #12 X 2 1/2" may split it. Ed
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Jay:
Yes, Spax screws really do work. They come complete with threads and everything! ;-)
However, more to your question, and following my rather flipant answer, the real issue when using a screw as you propose is the fact that all screws act as wedges. Splitting can be avoided by removing the material that the screw shank would ordinarily displace (drilling a pilot hole), or by placing the screw far enough away from the edge of the board that the material's interfiber strength is not exceeded. Small screws obviously displace less material, so they tend to cause fewer splitting problems.
Spax screws, as well as the many variations of sawtooth screws on the market (including our own ProMaster screws) all work basically the same way - the saw teeth are designed to cut the fibers as the screw is driven. This does little to reduce the material displaced by the screw shank. It does seem to make the screw drive more easily, and it does seem to reduce splitting under certain conditions.
Unfortunately, the edge grain of plywood is quite different than the face or edge grain of solid lumber. Plywood is easily de-laminated, and because of the cross grain laminations, a screw is threading itself into both edge grain and end grain. Thus, plywood is especially suscepitble to splitting when a screw is drive into edge grain.
There are several solutions to this: 1. Predrill the hole in the edge plywood edge grain. Use a bit slightly smaller than the screw shank, and use an extra-long screw to maximize the thread contact. Also, unless using our ProMax screws with their Optimized Thread Length, it is a good idea to drill a clearance hole in the first board so that the screw can not cross thread. 2. Excavate a recess in the plywood edge grain into which you glue a block of wood, which you can then drive a screw into using your preferred method. 3. Drill a 1" to 1-1/2" diameter hole in the face of the plywood, about 3/4" to 1" from the edge, but only about 3/4 of the way through the plywood. Then glue a matching sized dowel into the hole (make sure you orient the grain so that the face grain is parallel to the edge of the plywood). Drive the screw so that it threads into the dowel for a very strong joint.
Hope a bit of this helps.
Jim Ray, President McFeely's Square Drive Screws www.mcfeelys.com

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Not wanting to sound flippant, but wouldn't "Square Drive" be more accurately referred to as "Robertson"?
Or does that violate a trademark of some sort?
I have built furniture for family in the US (I'm in Canada), and I always use the Robertson (Square Drive) screws. They had to fix something their son broke, and I had to send them a screwdriver to do it because they couldn't buy a Robertson where they live!!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I doubt that you will find a more qualified guy to respond than Jim but..
P.L. robertson invented the them in 1908.
The namesake company is still in business:
http://www.robertsonscrew.com /
I suspect that Robertson is a trademark of the Robertson screw company, not unlike "Kleenex" is to "facial tissue"
FWIW, Mcfeeley's site (Jim's) does cite the inventor
http://www.mcfeelys.com/tech.asp
-Steve

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

ISTR that someone on this ng said that square drive are straight sided whereas Robertson are slightly tapered.
Is this true? I know the Robertson are tapered and like them that way (easier to put the screwdriver tip in), but know nothing about the US Square Drive brand.
Mike - who always buys Robertson wood screws.
PS - Pre NAFTA, all (almost all?) electrical stuff in Canada used Robertson or Robertson/Slot screw heads. Now a lot is Philips or Philips/Slot, which sucks - you can't get a Philips to stay on the end of the screwdriver and it takes two hands to put in a screw or bolt!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Michael:
This is one I have answered before, but I'm just too lazy to search for my prior postings, so here goes again. You can probably Google it though.
The Square Drive recess is an Industrial Fastener Institute (IFI) standard, and calls for 1.5 degree taper to each face of the recess (3 degrees total). To my knowledge, no manufacturer purposely makes the recess non-compliant. One of the major obstacles the inventory overcame was developing a basically parallel sided recess that was manufacturable. Providing a slight taper to the recess allowed for easy removal of the "punch" that forms the recess. The reason for the taper is thus one of manufacturability, not trademark (and of course, the patents expired long ago).
The term "Square Drive" is one that we have been using for almost twenty years, not because we were trying to establish a new standard or anything, but because we wanted a descriptive name for the recess when trying to promote them to woodworkers in the USA. There were already enough "vanity" recess names (Frearson, Phillips, Reed-Prince, etc) that meant nothing to the user not having prior knowledge of the recess shape (quick now, what is a Frearson recess?). Identifying the screws as "Square Drive" in our catalog helped the woodworker know what the screws looked like without research. I can't tell you that we coined the name "Square Drive", but the screws certainly were not in common use 20 years ago.
Your comment about the pre-NAFTA Robertson recess use on electrical parts is interesting. Most of the electrical stuff I work on now has Robertson recess screws, and much of it is of Canadian manufacture. Please don't tell me that the US market is starting to see the light just as the Canadians succumb to the sometimes illogical demands of the US market. Ironic, and rather tragic.
HTH
Jim Ray, President McFeely's Square Drive Screws www.mcfeelys.com
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Maybe not in common use but square drive screws as we called them were certainly used many years ago. In high school in the mid 60's I worked at a trailer & camper mfgr, Fleetcraft in DT Seattle and we used them for that. The only problem really was the bit to drive them in. It wore out (rounded end) very quickly unless your air drill was exactly parallel to the screw, which took a few extra seconds. Since time was money you had to work fast and that made for a lot of worn out tips which you had to buy, they were not supplied at company cost<sigh>. Of course the worn out bit meant a worn out screw head too so buyer beware - back then.
Jim wrote:
<snipped>

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Grandpa:
I probably should have been more specific when I said they were not in common use. Industry was starting to adopt them, especially the mobile home and recreational vehicle industry. Adoption was also fairly regional for some reason - probably word of mouth or cross-pollinatio as employees moved from one company to another. What I was trying to say was that they were not in common use by recreational woodworkers, even though there were in fact a few mail order catalogs selling asmall selections, even back then.
I really didn't mean to imply that they were unknown - heck, they were invented in 1908 in Canada, and have been the preferred recess type there for many many years. (In fact, the Canadian magazine "TODAY" initiated a subscriber survey in 1982, which resulted in the Robertson screw receiving the number one ranking of the best things about Canada. It even beat out the newfoundland dog, and the Canadian flag!
Jim Ray, President McFeely's Square Drive Screws www.mcfeelys.com
"Grandpa" <jsdebooATcomcast.net> wrote in message

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
What's not to like about a screw? ;).
Newfoundland (note the capitalized "N", are big friendly beasts but the darned things are about the size of a Shetland Pony and I would hate to have to feed one. Also, 1982 was still a bit too close to the adoption of the red maple leaf flag. I know even my dad, a WWII vet, swore that his flag was the Canadian Ensign (small Union Jack on a red field with the Canadian Coat of Arms in the corner) 'cause that was the flag he served and fought over. So I imagine that in 1982 there were still a lot of vets and others to whom the red maple leaf was too new, too different or whatever.
But a Robertson Screw! It doesn't get any better than that!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'd agree - the best out there.
BTW, Robertson was quite a prolific inventor. He also invented the tracer bullet in WWI.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Did you verify that with Mrs. Robertson?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
You know, this all begs the question, what makes this screw, or a torx tip or others better than the standard phillips or straight slot screws? I've used a lot of different ones over the years and have not found one to be 'better' than another. Were I to have to select one over the other, I'd opt for a combo phillips/straight slot. I am curious though if perhaps I'm missing something? A sincere question sir.
Jim wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Phillips bits are designed to cam-out when overtorqued.
Robertson/square bits are designed not to cam-out when overtorqued.
Slot bits slip out very often...
Grandpa wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 16-Apr-2004, Grandpa <jsdebooATcomcast.net> wrote:

A Robertson screwdriver will hold the screw and allow you to drive the screw with one hand. With a Philips, you have to use one hand to hold the screw and the other to drive it. This makes it much easier to drive a screw in an ackward spot with a Robertson. After a lifetime of using Robertson and all the others, I'd have to say it is the best overall.
Mike
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hi -
You're correct - it's a trademark. You can't use "Robertson", unless you buy the product from Robertson...
Cheers -
Rob Lee
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Where's Mr. Phillips when you need him?
Jon~
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Don't ask the Secretary.
".... if caught or captured, the Secretary will disavow all knowledge.." :)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I find that to be "a good thing". I don't know how many "square drive" tools I have thrown away over the years, but I still have every screwdriver with the Robertson name on it. That name on a tool (or a box of screws) really means something.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There are two versions... IIRC, Robertson is tapered slightly while square drive is not.
djb
--
Was that last sig line lame or what?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.