8mm button head tests

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Banquo

climber
Amerricka
Topic Author's Original Post - Feb 24, 2013 - 08:54pm PT
Minerals, who posts here on ST, sent me some 8mm button head anchors to test. I have been trying different drill sizes to see what works with them. But first some dimensional data:
Credit: Banquo

The split in the 8mm anchors increases the width of the shank by 22% while for 0.25” anchors the increase is 40%. So the increase is proportionally less for the 8mm anchors. The increase in diameter for the 8mm is 0.069” while for the 0.25” anchors it is 0.095” so the increase isn’t just proportionally less it is actually less. The 8mm isn’t just a scaled up 0.25” anchor which makes sense to me because of dimensional problems of scale. For a round section, the bending stiffness (moment of inertia) increases as the diameter to the fourth while the bending strength (section modulus) increases as the diameter to the third power. If you simply scaled up a 0.25” anchor it wouldn’t simply be proportionally strong or hard to drive. I am sure there are fabrication issues in scaling up also.

Next comes figuring out drill sizes. Carbide tipped masonry bits (SDS & A-Taper) are all oversize per ANSI B212.15 (which I found posted on some website and you can too). I am guessing that carbide bits are oversize so that a 1/4” rod or bolt will always fit in a hole drilled with a 14” bit. HSS twist drills are all just a bit undersize since a drill always makes a hole just a bit larger than the drill’s largest diameter.
Credit: Banquo

Test #1) Drilled with 8mm SDS and tested in pullout using a steel hanger which pried a bit. I had to use a 2 pound hammer in my effort to beat it into the hole. It crumpled and the head was flattened. I managed to mushroom and squash the anchor until the hanger was tight. It pulled at 960 pounds.
#1
#1
Credit: Banquo

Test #2) Drilled with 5/16” SDS and pulled with test fixture. I only got this one in about half way when it bent over. It pulled at 1960 pounds.
#2
#2
Credit: Banquo

Test #3) Was drilled too close to the edge of my granite block and spalled off the side so no result.
#3
#3
Credit: Banquo

Test #4) Drilled with an 11/32” HSS bit. I managed with much pounding to get this one all the way in and I tested it in pullout. My fixture broke at 2780 pounds. I couldn’t reattach to it so I chopped it.
#4
#4
Credit: Banquo

Test # 5) Drilled with an 11/32” HSS bit and tested in pullout with a hanger (some prying). It took much beating to get in and pulled at 2740 pounds.
#5
#5
Credit: Banquo

Test #6) 11/32” HSS tested in shear with a hanger. I mashed the head beating it in. The hanger broke first and then the head popped off with a maximum load of 4550 pounds.
#6
#6
Credit: Banquo

Test #7) Drilled with a 23/64” HSS bit and tested in pullout. It went in nicely and pulled out at 2720 pounds.
#7
#7
Credit: Banquo

In conclusion I would say that the 23/64” drill worked nicely but is very close to a 3/8” drill. Anything smaller than a 23/64 HSS (0.358”) bit is too small. There is a small range of drill sizes that will work since the largest dimension at the split is 0.385”. I would rather go ahead and put in a 3/8” bolt if I am drilling a hole of this size. A 3/8” carbide bit would drill a hole that is too large for the 8mm anchor. A 9mm carbide bit might work but they are pretty rare and I haven’t found them in the USA. Although the steel used in the 8mm anchors seems pretty soft to me, the capacity is certainly good if you can get the hole size right.

Spreadsheets as CSV in case anybody wants to open it in a spreadsheet:


ANCHORS,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
Split Shank Size,8mm,,"1/4"" x 1-1/2""",,"1/4"" x 1-1/4""",,,,,,,,,,,
,mm,in,mm,in,mm,in,,,,,,,,,,
Overall Length,45.97,1.810,41.73,1.643,34.98,1.377,,,,,,,,,,
Penetration Length,40.94,1.612,38.28,1.507,31.78,1.251,,1.169,,,,,,,,
Shank Diameter,8.03,0.316,6.07,0.239,6.10,0.240,,,,,,,,,,
Largest Split Dimension,9.78,0.385,8.48,0.334,8.53,0.336,,,,,,,,,,
Length of Split,27.89,1.098,22.00,0.866,21.84,0.860,,1.272,,,,,,,,
Difference Between Shank & Split,1.75,0.069,2.41,0.095,2.44,0.096,,,,,,,,,,
,,1.218,,1.397,,1.400,,,,,,,,,,
DRILLS,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
Recommended Drill,"1/4""",,"1/4""",,"5/16""",,8 mm,,Nov-32,,23/64,,9 mm,,"3/8""",
Type Measured (Carbide),"1/4 "" A-Taper (USA)",,"1/4 "" SDS (German)",,"5/16"" SDS (German)",,8mm SDS (China),,HSS,,HSS,,Don't have one,,"3/8"" SDS (German)",
,mm,in,mm,in,mm,in,mm,in,mm,in,mm,in,mm,in,mm,in
Measured Drill Dimension at tip,6.83,0.269,6.83,0.269,8.38,0.330,8.48,0.334,8.69,0.342,9.09,0.358,,,9.98,0.393
ANSI B212.15 (maximum),6.60,0.260,6.60,0.260,8.51,0.335,8.45,0.333,,,,,9.2,0.362,10.11,0.398
ANSI B212.15 (minimum),6.81,0.268,6.81,0.268,8.31,0.327,8.20,0.323,,,,,9.45,0.372,9.91,0.390
Published Size,,0.25,,0.250,,0.3125,8,,8.73,0.34375,9.13,0.359375,9,,,0.375
Actual/Published Size,,108%,,108%,,106%,106%,,,99.5%,,99.6%,,,,105%

Rhodo-Router

Gym climber
sawatch choss
Feb 24, 2013 - 10:18pm PT
thanks Banquo!
mike m

Trad climber
black hills
Feb 24, 2013 - 10:30pm PT
Buttonheads are always bomber.
Strider

Trad climber
ಠ_ಠ
Feb 24, 2013 - 10:56pm PT
Do you archive the data from your tests anywhere else, where they are all accessible in one place?

This is awesome info to digest and I appreciate the effort to put it together!

-nick
mike m

Trad climber
black hills
Feb 24, 2013 - 11:14pm PT
^^^Agreed. Most of the buttonheads I see are really old and are in varying states of deterioration.
Ron Anderson

Trad climber
Soon to be Nipple suckling Liberal
Feb 24, 2013 - 11:16pm PT
stronger than i thought.. Interesting info..
mucci

Trad climber
The pitch of Bagalaar above you
Feb 24, 2013 - 11:34pm PT
Thanks for the detailed report Dan!

Jesus, 8mm would be tough to send home if you were sketched out on lead!




How about a well placed 5/16th x 3/4" machine head rivet, pull and shear numbers? More of those on Yo walls than any other piece of metal.

Mungeclimber

Trad climber
the crowd MUST BE MOCKED...Mocked I tell you.
Feb 24, 2013 - 11:46pm PT
Banquo, I echo what Mucci said, if you have the time and inclination. I will definitely read the results and buy the drinks. :)






This below mimics everything I have heard about the 8mm Fixe split shafts. Essentially it's a crap shoot, and why would anyone crap shoot when they need it for upward progress. shame too. The old Rawl 5/16" were great on SMC hangers for lightweight work. you could pre-plug the splits into the hanger hole and have it stay. I have a few still, but I'm not doing enough back country work apparently. :)

Test #2) Drilled with 5/16” SDS and pulled with test fixture. I only got this one in about half way when it bent over. It pulled at 1960 pounds.
Scrubber

climber
Straight outta Squampton
Feb 24, 2013 - 11:46pm PT
Stronger than I thought too. Most of the ones around here have been replaced in the last decade or so. There's not much left of them after 20 years in our wet, coastal environment. I have seen the occasional stainless steel one over the years. No idea as to their cost or availability.

As someone who has pulled well over a hundred of these things to replace them with stainless wedge type anchors, I've made an interesting observation. Many of the split-shaft (compression) bolts I've removed have had one or both sides of their split partially or completely fractured prior to me removing them. This is conceivably due to the forces involved in beating the bolt into a tight fitting hole. (The cracked portion has clearly been rusting for some time before I got to it.)

Did any of the ones you sucessfully pulled show signs of cracking?

K
bhilden

Trad climber
Mountain View, CA
Feb 25, 2013 - 12:52am PT
I did a little math:

5/16" = .313"

8mm = .315"

So, it looks like 8mm = 5/16" or did everybody already know that?
Clint Cummins

Trad climber
SF Bay area, CA
Feb 25, 2013 - 04:14am PT
Nice work and analysis, Dan.

Minor point: it looks like Excel is up to its usual tricks - it has replaced 11/32 with Nov-32. Putting it in quotes '11/32 should help.
Don Paul

Big Wall climber
Colombia, South America
Feb 25, 2013 - 07:20am PT
Great work Dan. I'm a little surprised by picture #5 were you're pulling the bolt straight out from the rock. I thought bolts had no strength in that direction and could come right out, but you tested it at 2700 lbs. Someone else scared me by showing how easy it is to just pop them out with a chisel.
healyje

Trad climber
Portland, Oregon
Feb 25, 2013 - 07:26am PT
The old split-shank buttonheads out at Beacon are some of the most durable and hardest steel I've ever encountered. If the old homemade hangers on them weren't shite they'd still completely bomb.

Couldn't get them out with tuning forks and I finally tried my battery-powered Sawzall with a brand new Lennox blade that will cut a stud like swiss cheese - the blade burned to nothing making little more than a scratch on the buttonhead. Bummer there aren't better hangers on them.
rick d

climber
ol pueblo, az
Feb 25, 2013 - 09:04am PT
dan-

if you want to try a couple rawl 5/16 for tests let me know I have about a dozen (would like to keep a few). The best test for them is a hand drilled hole.

rick
tucson, az
Banquo

climber
Amerricka
Topic Author's Reply - Feb 25, 2013 - 10:27am PT
Do you archive the data from your tests anywhere else, where they are all accessible in one place?
I am not very organized in this regard.


Did any of the ones you sucessfully pulled show signs of cracking?
I didn't see any. The steel is very soft and malleable. I wouldn't expect cracks.

5/16" = .313"

8mm = .315"

So, it looks like 8mm = 5/16" or did everybody already know that?
I don't have any 5/16" to measure but the 1/4" shanks are 0.239" so I suspect the 1/4" size means they will fit in a 1/4" hole. The 8mm shanks are actually 8mm. A 5/16" may or may not have a 5/16" shank. This is what happens when there are no standards.

Someone else scared me by showing how easy it is to just pop them out with a chisel.
Having pulled a few 1/4" anchors myself, I know that some old ones can be pulled with little effort while others are very hard to pull. New 1/4" anchors tested 3340 lb in shear and 1860 pullout.

if you want to try a couple rawl 5/16 for tests let me know
Sure would, I'll send you my address. A couple to measure and then test in shear and tension.
Roughster

Sport climber
Vacaville, CA
Feb 25, 2013 - 10:34am PT
I always find this stuff really interesting, so thank you for posting it! I have posted this before but I will say it again. I once put a bolt into Table Rock, which is rock of the shittiest quality that is still boltable, that wiggled and spun. I just couldn't get it to tighten down all the way.

I decided to pull it, instead of just removing the inside stud and sealing to see just how "bad" this placement was. I spent the next 4 hours absolutely wailing on it with a 5 lbs sledge hammer funk device. I even started funking up and down and left and right which made the hole huge, and I still couldn't get it to pull.

I finally gave up, unscrewed the bolt from the sleeve and patched the hole, but from that day forward, my confidence in bolts was that, beyond the weird / freakish which I do recognize happens on occasion, they are frickin unbelievably bomber if you get them all the way into a hole.
slabbo

Trad climber
fort garland, colo
Feb 25, 2013 - 11:00am PT
I have placed quite few 5/16 over the years, both rawl and Fixe. Most of these were hand drilled and i always flared the hole slightly to prevent fracture. Whether this compromised strength, i don't know, but the Fixe especially would not go all the way in without the flaring.

most of these bolts certainly seemed bomber enough and were fall tested but you never know and for sure at 20+ years, they are due for replacement anyway.

I noticed Fixe ? hangers for your test. Do you think that the added thickness was a factor with such short bolts ?????

john
guyman

Social climber
Moorpark, CA.
Feb 25, 2013 - 11:30am PT
I hate 3/8 button heads... when the head has many hammer hits, beware!

The head can and will be worked, it will break off.

Kris S was getting lowered and cleaning the draws at Church Dome, "Jacobs Ladder" was the route if I recall.... its slightly overhung... he was swinging in to grab the draw, grabbed it and the top (the head) broke off!!!!! It didn't even hold at all!



Banquo

climber
Amerricka
Topic Author's Reply - Mar 25, 2013 - 01:52pm PT
supertopo member "rick d" sent me two 5/16" anchors to test and as a bonus two old Star Dryvins.

Two Star Dryvins and two 5/16" split shank anchors
Two Star Dryvins and two 5/16" split shank anchors
Credit: Banquo

I am interested in testing the Star Dryvins even though the voice in my head says there is no point since they are considered to be bad by one and all. ASCA says:

The Star Dryvin is the only sleeve-and-nail bolt we found. This anchor, once commonly used in sandstone, utilizes a lead sleeve and a steel nail. You tap the sleeve in the hole, and then hammer the nail in, spreading the sleeve. In the best rock the 3/8inch Dryvin only holds 1400 pounds in shear and less than that in pullout. In sandstone, where Dryvins were thought to be a good alternative for drilled angles these bolts are unbelievably weak-we pulled one out with our fingers.

Rickety and somewhat expensive at $2 each, there's no excuse for ever using a Dryvin. If you see a star icon on a nail head that's embedded in a sleeve, yank the sucker out and put in a real bolt.

If I do test them , I would like to try one in shear and one in pullout. I would expect the same results for the two lengths in pullout but the longer one might be better in shear. What to do?

The 5/16" anchors are interesting in comparison to the 8mm anchors. The stated sizes are very close but the 5/16 has a smaller actual shank diameter and a larger dimension at the split. I think it is designed to be placed in a 5/16" carbide hole which is slightly larger than 5/16. Anybody know what drill was specified?

Anchors: 8mm, 5/16" and two 1/4"
Anchors: 8mm, 5/16" and two 1/4"
Credit: Banquo

8mm Fixe, 5/16 Rawl, 3/8" Star Dryvin, 1/4" Powers
8mm Fixe, 5/16 Rawl, 3/8" Star Dryvin, 1/4" Powers
Credit: Banquo

Updated dimension table.
Credit: Banquo

CSV of spreadsheet.

ANCHORS,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
Split Shank Size,8mm,,"5/16"" x ?",,"1/4"" x 1-1/2""",,"1/4"" x 1-1/4""",,,,,,,,,
,mm,in,mm,in,mm,in,mm,in,,,,,,,,
Stated Diameter,8.00,0.315,7.94,0.3125,6.35,0.250,6.35,0.250,,,,,,,,
Overall Length,45.97,1.810,43.31,1.705,41.73,1.643,34.98,1.377,,,,,,,,
Penetration Length,40.94,1.612,39.24,1.545,38.28,1.507,31.78,1.251,,,,,,,,
Shank Diameter,8.03,0.316,7.72,0.304,6.07,0.239,6.10,0.240,,,,,,,,
Largest Split Dimension,9.78,0.385,10.24,0.403,8.48,0.334,8.53,0.336,,,,,,,,
Length of Split,27.89,1.098,28.07,1.105,22.00,0.866,21.84,0.860,,,,,,,,
Difference Between Shank & Split,1.75,0.069,2.51,0.099,2.41,0.095,2.44,0.096,,,,,,,,
Split Dim./Shank Diam.,,1.218,,1.326,,1.397,,1.400,,,,,,,,
,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
DRILLS,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,
Recommended Drill,"1/4""",,"1/4""",,"5/16""",,8 mm,,"11/32""",,"23/64""",,9 mm,,"3/8""",
Type Measured (Carbide),"1/4 "" A-Taper (USA)",,"1/4 "" SDS (German)",,"5/16"" SDS (German)",,8mm SDS (China),,HSS,,HSS,,Don't have one,,"3/8"" SDS (German)",
,mm,in,mm,in,mm,in,mm,in,mm,in,mm,in,mm,in,mm,in
Measured Drill Dimension at tip,6.83,0.269,6.83,0.269,8.38,0.330,8.48,0.334,8.69,0.342,9.09,0.358,,,9.98,0.393
ANSI B212.15 (maximum),6.60,0.260,6.60,0.260,8.51,0.335,8.45,0.333,,,,,9.2,0.362,10.11,0.398
ANSI B212.15 (minimum),6.81,0.268,6.81,0.268,8.31,0.327,8.20,0.323,,,,,9.45,0.372,9.91,0.390
Published Size,,0.25,,0.250,,0.3125,8,,8.73,0.34375,9.13,0.359375,9,,,0.375
Actual/Published Size,,108%,,108%,,106%,106%,,,99.5%,,99.6%,,,,105%
rick d

climber
ol pueblo, az
Mar 25, 2013 - 04:21pm PT
dan-
we actually tested two 1" x 1/4" dryvin's in concrete at Geir Hundal's house and got a respectable 800-900lbs shear out of them.

I can see if I can the OD of a 5.10 --5/16" bit to guestimate the hole size.

A photo image of the heads will also reveal the "R" for rawl.

From standing on 100's of 3/8" dryvins I believe the stats will be pretty good when said and done.

lead shields man. woooohooo
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