If memory serves my 84 Reliant had TTY. might have been that 86
Escort with the Mitsubishi engine-- but they are the newest cars I've
had the heads off of.
Here's a bit about them- but no models mentioned;
Same here, and TS sells their hardware by the pound. It's always
where I go first. I just bought a boatload of grade 2 & 5 carriage
bolts, nuts, washers, etc. for around $8 ($1.99/lb). The grade 8
are a little more expensive if you need them, but not unreasonable.
I was at Lowes later for something else, so just did a quick double
check to see how far off they were. Grade 1 bolts alone were nearly
8 (1/2 x4) = $8.80 ($1.10 each).
4 (1/2 x6) = $6.00 ($1.50 each).
The irony is that I'm using a plan I found at Lowes.
BTW: Using a drill gauge for sizing!
We use a card with various holes in it, originally designed we think
for sizing knitting needles?
But the holes are marked in metric on one side and on the other in
64ths, 32nds etc.
And what diameter would that be, since lags are tapered? And if there were
such a diameter, you would mean "root diameter" or minor diameter -- right?
But that's ok.... I'm sure the concept of conventional vs climb cutting is
going to take another few weeks to properly gel in your brain -- all this
other stuff will come in due time. Heh, mebbe you can study with yer buddee
Altho ahm no 'spert on wood, I doubt that the pilot hole should be exactly a
root diameter (if there were one) for wood. After all, yer not tapping the
wood like metal.
Mebbe there is a woodworker's equiv to Machinery's Handbook that has this
spec -- heh, mebbe even Machinery's handbook has it!
I'm sure there has to be some compression of the wood fibre, for adequate
strength, when drilling pilots. 1/8" actually sounds about right.
I measured a 1/4", just one, and its root measured .186-.187 top to bottom.
I don't imagine lags are a precision item, tho.
And one of the links someone posted gives the pilot as 3/16 in softwood,
7/32 in hard!
It also mentioned grease or vegeteable oil as a lube, but cautioned against
1/4 lags are fragile, tho. I'd use 5/16 on anything semi-substantial.
> > The next natural drill size is .187, or 3/16".
For optimum strength in solid wood you actually want to drill the pilot
hole smaller than the root diameter. Specifically between 0.7 and 0.9
times the root diameter, depending on the density of the wood in
question--softwood gets a smaller hole.
Long lore, at least...
I don't have a direct URL; I'd expect you'd find the information in some
of the US Forest Products Laboratory technical publications. It was
something I was taught way back in one of first HS ag-ed classes is
first I recall it personally, anyway...don't recall if it was taught as
a specific ratio, only "tubafores get smaller, rr-ties get bigger" was
the gist of it. :)
I don't see the point. The pilot hole sizes quoted work for nails
where compression determines strength but I don't see any benefit in
having a pilot hole of less than the root diameter of a threaded
The point is to have a larger pilot-hole in softer woods than hardwood
to minimize the effort of installation but to ensure a full bite which
can be marginal if use a full root diameter for pilot, particularly in
softwoods that tend often to "crumble".
No claim made (at least by me) that there's any _precise_ ratio other
than the aforementioned bigger/smaller based on the material.
I'd still wager there is some information at US FPL but I've not taken
time to search for it.
It's in "Wood As An Engineering Material", Page 7-11. What they say is:
"For low-density softwoods, such as the cedars and white pines, 40% to 70%
of the shank diameter; for Douglas-fir and Southern Pine, 60% to 75%; and
for dense hardwoods, such
as oaks, 65% to 85%. The smaller percentage in each range applies to lag
screws of the smaller diameters and the larger percentage to lag screws of
Excellent reference, J. Thank you for posting that, it is very much
The lag bolt which snapped off had an average shank diameter of 0.182".
Sixty percent of this value is 0.1092, while seventy five percent of this
value is 0.1365, which puts a pilot bit of 1/8" right in the middle.
On Thu, 17 Dec 2009 11:19:09 -0800, "Jon Danniken"
What do you mean by "shank diameter"?
Machinery's Handbook lists the "body" or "shoulder" diameter of a 1/4"
lag bolt as between .237" and .260". This is the area that is not
The "root diameter" is listed as .173". This is the diameter of the
remaining cylinder after the threads are formed.
(American National Standard Square Lag Screws - ANSI/ASME
BUT Jon,,,,,, While it is a kewl reference that agrees with what you were
using as a pilot hole, how did that work out for you?
The information could be out dated for readily available fasteners today.
If might be a new publication using old data.
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