Jacob
What goes around comes around.
Is there a coach bolt (square bit of shank) but countersunk with no slot so it'd fit flush with the surface? Say 5mm dia?
CS coach bolt?
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Myfordman
AKA 9Fingers
I’ve certainly seen bigger ones over the years but never that small.
Jacob
What goes around comes around.
5mm thread
Myfordman
AKA 9Fingers
They seem to be known as flat countersunk square neck bolts. you might have more luck omitting the "coach" reference from your search.
that said I've only found m10 and above.
The merkins seem to call them plow bolts but again seem to be larger and naturally with unified threads.
Best bet might be to phone a trade fastener stockist but you might be looking at MOQ of 100-200 pieces
that said I've only found m10 and above.
The merkins seem to call them plow bolts but again seem to be larger and naturally with unified threads.
Best bet might be to phone a trade fastener stockist but you might be looking at MOQ of 100-200 pieces
Phil Pascoe
Established Member
but not countersunk.
Agent_zed
Established Member
depending on what you are securing you might just be able to get away with 5mm countersunk bolts having enough friction to tighten without turning. Or perhaps a blob of weld or two on the shank
Homeless Squirrel
Established Member
once get desired bolts! Get a socket that fits heads and measure outer diameter of socket then shallow bore out holes with a forstner/flat bit etc that matches outer size of socket to required depth, once done have options of using a ratchet or power tool that way flush fitting done that many times.
sometimewoodworker
Established Member
All the coach bolts around here don’t have a slot though the head is slightly domed so you would just drill a recess
Inspector
Nyuck, Nyuck, Nyuck!
Try searching for Countersunk Coach Bolts, Plow Bolts, Elevator Bolts, Countersunk Square Bolts, Din 608 Flat Countersunk Square Neck Bolt With Short Neck and wherever they lead you. Eventually you'll get there.
Pete
Pete
BillHoughton
Established Member
In the U.S., they're called "plow bolts." I don't know if they come that small here. My hardware store used to carry them, but not sure if they still do.
Can you counterbore the stock into which you're placing them, so you can use a conventional coach (carriage in the U.S.) bolt or even a panhead bolt/machine screw of some kind? A word about coach/carriage bolts: in soft wood, that square can strip out. It's often better to have a bolt/screw with a head that takes a holding tool of some sort (screwdriver, for instance), even though it means counterboring to accept the head.
Depending on how close to flush you need to get, there are also elevator bolts, with a very thin, large diameter head atop a squared off section on the shank; my hardware store carries these - just saw them t'other day - but not sure of minimum diameter. 5mm shank size is pretty small.
Can you counterbore the stock into which you're placing them, so you can use a conventional coach (carriage in the U.S.) bolt or even a panhead bolt/machine screw of some kind? A word about coach/carriage bolts: in soft wood, that square can strip out. It's often better to have a bolt/screw with a head that takes a holding tool of some sort (screwdriver, for instance), even though it means counterboring to accept the head.
Depending on how close to flush you need to get, there are also elevator bolts, with a very thin, large diameter head atop a squared off section on the shank; my hardware store carries these - just saw them t'other day - but not sure of minimum diameter. 5mm shank size is pretty small.
Elevator bolts seem to be M6 minimum size:
https://go4b.co.uk/products/bucket-elevator-components/elevator-bolts
On one of the Engels Coach Shop YT videos, he makes what you are after by forging a standard coach bolt. Drill a hole into a piece of steel bar, countersink to the required depth, form the square with a file. Heat the head of a standard bolt to red, drop into the die and pound with a hammer.
https://go4b.co.uk/products/bucket-elevator-components/elevator-bolts
On one of the Engels Coach Shop YT videos, he makes what you are after by forging a standard coach bolt. Drill a hole into a piece of steel bar, countersink to the required depth, form the square with a file. Heat the head of a standard bolt to red, drop into the die and pound with a hammer.
BillHoughton
Established Member
Forging your own bolt for a one-off seems like a lot of work.
Kittyhawk
Established Member
We have both galv and stainless standard coach bolts here in 5mm. With the stainless ones it's easy to put them in the lathe and skim the rounded heads flat. With care an angle or bench grinder would work. The head adopts the shape of a flat disc but is ok for light duty applications.
ajs
Established Member
This is the kind of question that makes me take a step backwards first. What are you trying to do and why do you think a coach bolt is the best way of achieving it? It may well be there is another way of achieving the same ends.
Are you after the security of a coach bolt against tampering? Or is this simply the stop the bolt rotating in the outmost part?
Why must it be countersunk? Is it the case that clearance is needed for something to fit or slide above it - in which case can it be recessed? Or must the surface be smooth, in which case recessed and plugged or filled?
Options that immediately come to mind are either a regular square head bolt or recessing and plugging the head, but I can't help feel there is some detail missing here which would suggest an alternative solution.
Are you after the security of a coach bolt against tampering? Or is this simply the stop the bolt rotating in the outmost part?
Why must it be countersunk? Is it the case that clearance is needed for something to fit or slide above it - in which case can it be recessed? Or must the surface be smooth, in which case recessed and plugged or filled?
Options that immediately come to mind are either a regular square head bolt or recessing and plugging the head, but I can't help feel there is some detail missing here which would suggest an alternative solution.
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