02GF74
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| posted on 17/12/08 at 02:16 PM |
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how to make a cone on the end of a bolt?
I want to replace a bleed screw by a socket screw (aka grub screw) but need to make a cone on the end.
Any tips on how to ensure the cone will seal?
My plan is to use engineer's blue, screw into the caliper then see if I get a continous ring - good?
Tools I have are a drill press and file.
I am not sure if making a gauge will be accurate enough.
So ideas ....?
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thunderace
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| posted on 17/12/08 at 02:21 PM |
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can you not just buy one??
as i dont think you will be able to do it even if you use a lathe.
its not going to be easy to match .
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Russ-Turner
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| posted on 17/12/08 at 02:24 PM |
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That will be really tough to do IMO. Even a nipple on one of our Performance Friction calipers leaked once after six hours of use from new!!
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02GF74
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| posted on 17/12/08 at 02:25 PM |
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quote:
Originally posted by thunderace
as i dont think you will be able to do it even if you use a lathe.
its not going to be easy to match .
oooh, that sounds like a challenge!!! 
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Mr Whippy
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| posted on 17/12/08 at 02:29 PM |
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stick it in a drill (high speed) and take a angle or bench grider to the end while its spining
Fame is when your old car is plastered all over the internet
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02GF74
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| posted on 17/12/08 at 02:30 PM |
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^^^ yes, that is how I plan to make it - but using a file.
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myke pocock
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| posted on 17/12/08 at 02:36 PM |
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stick it in a drill (high speed) and take a angle or bench grider to the end while its spining
Sorry, but do it that way and you will never get it to seal properly, it just aint accurate. Have you thought of using a hex head bolt with a copper
washer under the head?
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Mr Whippy
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| posted on 17/12/08 at 02:44 PM |
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quote:
Originally posted by myke pocock
stick it in a drill (high speed) and take a angle or bench grider to the end while its spining
Sorry, but do it that way and you will never get it to seal properly, it just aint accurate. Have you thought of using a hex head bolt with a copper
washer under the head?
already done this for brake bleed screws, works fine as the metal is soft enough to deform and seal, thats why I had to do it in the first place as
they were marked, just cleaned them up on the bench grinder.
Fame is when your old car is plastered all over the internet
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londonsean69
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| posted on 17/12/08 at 02:48 PM |
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Erm, so how will you bleed your brakes??
Just out of interest, why do you want to replace it?
If the above is not a problem, you could do as the others say, but maybe finish off by taping some (wet) wet and dry to a flat surface, then doing the
final turning on that (or could offer the wet and dry to the piece while it is in the drill press)
Will leave a better surface than a file (unless you finish with a very fine file.
If it is for a caliper, do you have an old junk one? If so, you can use lapping compound to finish the screw, but it still might not be perfect in the
new caliper.
The biggest problem will be maintaining a correct and consistent angle to match what is in the caliper.
Sean
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Mr Whippy
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| posted on 17/12/08 at 02:55 PM |
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quote:
Originally posted by londonsean69
The biggest problem will be maintaining a correct and consistent angle to match what is in the caliper.
Sean
if you look down the hole, the angle in the caliper is not the same as that of the screw as it relies on a small contact area to seal. Thats why often
a small ring mark is left on the cone of the screw. This needs cleaned off sometimes to get the screw to seal.
[Edited on 17/12/08 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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londonsean69
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| posted on 17/12/08 at 03:00 PM |
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quote:
Originally posted by Mr Whippy
if you look down the hole, the angle in the caliper is not the same as that of the screw as it relies on a small contact area to seal. Thats why often
a small ring mark is left on the cone of the screw. This needs cleaned off sometimes to get the screw to seal.
[Edited on 17/12/08 by Mr Whippy]
Fair enough, it's been over 5 years since I have had a caliper apart 
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DarrenW
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| posted on 17/12/08 at 03:00 PM |
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Dare i ask why you would want to do such a thing.
Are you planning on making your own tyres too?
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Mr Whippy
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| posted on 17/12/08 at 03:11 PM |
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quote:
Originally posted by londonsean69
quote:
Originally posted by Mr Whippy
if you look down the hole, the angle in the caliper is not the same as that of the screw as it relies on a small contact area to seal. Thats why often
a small ring mark is left on the cone of the screw. This needs cleaned off sometimes to get the screw to seal.
[Edited on 17/12/08 by Mr Whippy]
Fair enough, it's been over 5 years since I have had a caliper apart
lucky you 
Fame is when your old car is plastered all over the internet
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MikeCapon
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| posted on 17/12/08 at 04:04 PM |
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Standard (cup point) socket screws already have a 118° angle on the end which finishes at around half the diamter of the screw before the
'cup' return.
Cone point socket screws have a complete point although I'm not sure of the angle. Have a look at one of the manufacturers sites. Unbrako is a
(very) good make.
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omega 24 v6
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| posted on 17/12/08 at 05:29 PM |
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Sorry but the proper parts are available at a minimal cost. What your suggesting is a BODGE. Don't do it you know it's not safe or
sensible.
If it looks wrong it probably is wrong.
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dnmalc
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| posted on 17/12/08 at 11:03 PM |
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the bleed nipple is normally designed to be softer metal than the caliper and is designed to distort to achieve the seal. Using a pointed steel bolt
to achieve the same sealing will require higher torqes and risk stripping the thread in the caliper. I would seriously consider either using a brass
grub screw which will often come with a taper on the front or altenatively use a plain bolt which does not bottom out and then seal the system by
using a Dowty sealunder its head.
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C10CoryM
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| posted on 18/12/08 at 01:38 AM |
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Why not just weld the end of the bleeder?
So long as you can do it well enough to stay on at high pressure that is.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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greggors84
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| posted on 18/12/08 at 09:26 PM |
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quote:
Originally posted by omega 24 v6
Sorry but the proper parts are available at a minimal cost. What your suggesting is a BODGE. Don't do it you know it's not safe or
sensible.
Well said. Making parts yourself is what this forum is all about. But when your saving a couple of quid on a part that stops all your brake fluid
gushing out your caliper when you stomp on the brake.
Just not worth doing.
Or is there a really good reason for it?
Edit: After reading the other post I now see its for a bicycle, not quite so dangerous, still...
[Edited on 18/12/2008 by greggors84]
Chris
The Magnificent 7!
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