Flat Head Bolts

Here's ons potential source.

TORX PLUS® Low Profile Head Drive System - Increased Screw Drive ...

Or this from recotools.

www.recotools.com/norway.html

Thanks for this (we call those elevator bolts) but the shank must be full thread to the underside of the head of the bolt.

That's right. You said that.

Threaded rod (all-thread) and low profile nuts won't do it?

Hi:

I actually checked the other link to Acument and they might have just what I need. The Strux or the Torx Low profile head fasteners might do the trick. If not you have given me some ideas on where to look.

Threaded rod would be awkward in an assembly situtation and would be difficult to get the required structural strength rating.

Thanks again

I have this problem all the time, and cannot find a bolt that doesn't have some shoulder. I have to make them myself by turning the shoulder on a manufactured fastener of the grade required. This is a pain in the ass, and I often just redesign the connection if possible.

I'd like to help, but I don't understand why you need high strength bolting to fasten medium gauge sheet. Why is such a low profile necessary. Does "cannot be screwed together" mean sheet metal screws. Will the pieces need to be disassembled regularly. Help me help you by giving more details.

Hi:

I actually looked into modfying but as I need large quantities that isn't too practical.

The guages run from min 16 ga to as heavy as 12 ga, possibly 10 ga and building code calls for min grade in this application which is a structural assembly.

The flat head is required as there will be other materials secured to the outside face of the metal and heads of course interfere. I did look at clinch fastening ut again not practical for the application. The sections are shipped to specific locations and then assembled.

Cannot be screwed means any screw type fastener whether self drillers, sheet metal etc.

Redsign would defeat the purpose of the design and engineering so can't go that route either.

Thanks for your input

I bought a winch some time ago. Included in the hardware kit were some 5/16 bolts with low profile heads. Grade 8. So, I know they are available. I got the winch from Harbor Freight (usual disclaimer). Is there a Harbor Freight store near you?

Or,

1/2-13X1-1/2-COARSE-BUTTON-HEAD-CAP-SC-PLAIN- 100-Pieces-Per-Carton

?

Hi:

No Harbor Freight here, I am in Alberta, Canada. Will check them out all the same,

Looked at Pan Head - Button Head fasteners bu tthey still have too much projection.

Leland Idustries does make a flat head fin neck bolt but only in 1/2" and not in the correct grade and I don't really want a fin neck either.

Thank you again,

I tried this: http://www.mcmaster.com/#specialty-bolts/=5tgat4

Your problem, as presently conceived, may be insoluble. If the bolt head is very thin, the shear strength of the head where it meets the shank may not be enough to equal Grade 5 specs. The strength of the fastener depends not only on the material but also on the geometry. However, you say you have 1/4" allowable head projection, so there may be some fasteners on adjacent pages to the one above that could work.

Check out button head, truss head, and pan head configurations. Of those, perhaps truss head is the best.

Hi:

Thanks for the help. The 1/4" is max but would prefer less if at all possible. Leland does make a bolt with a flat head just under 1/4" but only in 1/2" shank size. These are a grade 8.2 bolt as well.

The McMaster-Carr catalogue is an amazing collection of products and it would seem they do have what I am looking for or something very close to it. This is going to take a while to go through....

Thanks again

Hi:

Thanks for the input and link. The issue of grade relates to engineering as this is a structural assembly so has min specs which include grade 5. Looked at grade 2 bolts but they are way too weak. Original specs was A-325 structural grade....

I did look at the low profile pan head machine screws but the drive is slotted or phillips and won't make as tight a connection as a nut with wrench or torx drive on the head of the bolt.

Flat head with fins do connect tightly as the fins grip but again project too high or are not available in the smaller size. Fin neck would work if I could find them in 3/8" x 3/4" shanks....

Could have them made for me if I wanted a few million or so but I only need about 10,000 for starters

"The issue of grade relates to engineering as this is a structural assembly so has min specs which include grade 5. Looked at grade 2 bolts but they are way too weak. Original specs was A-325 structural grade."

Unless you're not telling us something, I don't see how joining 12 to 16 gage sheet metal could possibly require a grade 5 fastener. 

As I mentioned earlier, these are steel sections which are being assembled into a structural shape. The guages used are typically the same throughout in each assembly. Some of these assemblies are made from heavier guage material up to 12 guage.

As well these assemblies will be subject to various loads.

If there aren't any issues regarding confidential information with your project, you should explain with some detail what you're trying to do. Your material specs and fastener specs contradict each other somewhat.

Hi;

I must again apologize as there are indeed some confidentiality issues.

Essentially the sections being connected are the same guage within an assembly, different assemlies use different guage metals some as thick as 12 or occassionally 10 guage. The whole problem is the fastener heads which cannot project more than 1/4" above the outer face of the metal. Inside doesn't matter so of course will use a nut.

The whole assembly must be of a design that allows it to be assembled then dismantled and re-assembled elsewhere, thus the bolts versus screws, rivets or welding.

There was a recent CR4 discussion (and I cant recall the topic) which led to a US supplier of something like this + a similar broad flat head mating female half. The sort of attachment ideal for body panel joins and where you might use a wide head rivet but you want a flat low-protruding surface on both sides. I cant now even find the US manufacturer to help you but they are around. Any help?

Hi:

Thanks for your input. I have found those particular pan head low profile bolts which are sadly, unrated. Otherwsie they look like they would do the job nicely.

I also need to apologize as the low profile requirement is on one side of the assembly only. I actually am looking at using serrated flange nuts on the other side to lock the connection together.

At one time I even looked into using 3M brand adhesives but they don't quite work as they are extremely difficult to take apart without damaging the materials used.

I am hoping to find a company that manufactures a low profile bolt similar to the ones made by Leleand Industries which have a 3mm head height but only in 1/2" shank or bigger. I need 5/16" or 3/8" for this application.

They do make a dome head fin neck bolt but it projects too far above the metal surface.

You may want to look into "undercut flathead" screws, though I've only seen them up to 1/2" diameter, and don't know what grades are available. See http://www.winkfast.com/Phil-flat-undercut-ms.html for a quick reference to what I'm talking about. I'd suggest calling a rep for Komar (http://www.komarscrew.com/) and asking. No affiliation, though we ARE a customer of theirs.

It may be worth investigating use of metric fasteners, though the standard 90 degree heads are not going to help (vs. 82 deg.). It just broadens your options.

Please see the following link http://www.henrob.co.uk/languages/english_aus/index.htm Gordon Australia

(The link leads to a description of Henrob Self-Piercing Rivets). Rivets might be a good way to attach one layer of sheet metal to another, but the Original Post (OP) said, "...the pieces cannot be welded, riveted or screwed together" (my added emphasis).

Hi All:

I wanted to thank everyone for their suggestions and help. I did finally find a bolt with a large hex head at less than 1/4" projection that is rated at Grade 8 with full thread. It does have a dog point but that doesn't matter to me and is available in Canada.

Thanks all

May i ask where exactly you located those bolts. company name etc.