Brake line double flare fitting help..

[Mr Fixit]

Hi Group,

I have a fitting that is not available except by one vendor and their cost ($30.00) is more than I'm willing to lay out when I think I can make the same thing... The drilling, threading and machining is something I feel ok about. It's' the flare bulb in the bottom that I'm not sure how to make.

The hole is threaded and has a double flare bulb in the bottom for the brake line fitting to seal against. How would you drill this hole to get the proper Major Diameter to thread the inside and cut the bulb in the bottom.



It screws into the wheel cylinder and has a banjo fitting that aligns with the hole in the side for a bleed port and the brake line fitting screws into the hex end with the Double flare bulb in the bottom.

I look forward to any help that you can provide.

TX
Mr fixit for the family
Chris

[Bented]

Form tool, similar to an endmill with the feature ground into the end.

If thousands are required one may also incorporate the thread diameter in a single tool, one plunge move.

[oxford]

On some of the stuff that I have screwed around with that was similar, the flare at the bottom wasn’t machined into the fitting. It was a separate piece that was pressed into a hole.

You may be able to find the piece separate and do something similar.

[Chipps]

Does a flexible (rubber) line screw into the hex?
Or metal line with nut?

You could make the fitting for regular metric bubble flare as the tip of a 135* drill works great to seal- no form tool required. Then match with bubble flare metal or flex line.

[BigMike782]

30.00 is a bargain.

[paul463]

On some of the stuff that I have screwed around with that was similar, the flare at the bottom wasn’t machined into the fitting. It was a separate piece that was pressed into a hole.

You may be able to find the piece separate and do something similar.

I did exactly this with a fitting on my project truck.
Made a flare seat similar to this;

[deltap]

I would try to single point it with a hand ground thread tool. The key is to have thread relieved at bottom of hole to major dia. so there is room to to cut inverted flare cone. Is the spec for the cone 45 deg? Definitely for someone with more time than money. Might scrap a few getting it figured out.

[CalM]

Bore the hole for the threads as one feature.

Then with a suitably ground boring tool produce the undercut "major diameter of the threads", that also has the profile to produce the V profile for the flair.
That could be two tools, but space is tight, and the flair feature is small.

As mentioned, PRACTICE on a piece of scrap! Making two tries on junk is way better than scrapping a piece that you have time into.

On your finished piece, do this detail FIRST in case things go badly . I assume you are using bar stock as raw material.

[rdfeil]

Not exactly a replacement, but how about a double flare to 1/8 pipe fitting. Then modify the original to accept the 1/8 fitting.

[rdfeil]

Another question... What is the problem with the original fitting?

[Mr Fixit]

HI Group,

Can anyone show me an example of the form tool you speak of? Is it a lathe operation or a milling operation? Chipps, it's the latter a rigid 3/16" pipe with a double flare fitting with 3/8" x 20 BSF thread which I do have a tap & die for. It has the regular 45* flare angle like a double flare has. Yeah $30.00 might be a bargain but I have the tools so I look forward to the challenge with a little help from folks here.

Paul 463 was it just a press fit? I wonder about sealing the fitting in the bolt, any soldering or sealant used? The original is borrowed from a friends car to measure and get dimensions from. My car did not have them and there is no way to bleed the hydraulics to the wheel cylinders without it.

I have hex 1215 solid stock that I will be making these from. I can get 12L14 too but thought the 1215 was a better choice. I figure test runs and experimenting would be part of it since it's new to me and I'm a HSM hobbyist there will be learning curve, just like the wheel cylinder sleeving that was a success recently. I was thinking of aluminum test pieces in round to get the hang of it but I'll need to figure out the grinding of tooling first.

So, if anyone has any suggestions, links, or pictures of form tooling that is mentioned above, I would greatly appreciate it.

TX
Mr fixit for the family
Chris

[rdfeil]

Chris,
A "Form Tool" is a custom lathe tool ground to the inverse shape of what you want the final part to be. You grind the tool yourself from a HSS blank. It takes care and time to get it right.

[macona]

30.00 is a bargain.

Yup. I would not bother for a one off.

[Mr Fixit]

Thanks rdfeil,

I thought that was the comment but when a mill tool was mentioned I was confused. So, I need to use the Dremel to shape a HSS bit in the shape of the bubble, what sort of relief should it have, just the bottom or a top rake too? I figure it would be 1/2 of the shape 1- 45* with a flat end for the bottom.

I agree Macona but I need 4 of them,$$$ . Besides I will learn something new about form tool cutting and if I muck it up then I can still buy them, which is a good backup.

TX
Mr fixit for the family
Chris

[oxford]

Paul 463 was it just a press fit? I wonder about sealing the fitting in the bolt, any soldering or sealant used?

TX
Mr fixit for the family
Chris

The ones I have seen were just press fit if I remember correctly. There may have been some sort of sealant but definitely no solder.

These we’re on a motorcycle caliper and I had to remove them so I could use a standard banjo bolt and crush washers with the custom brake lines. I just screwed a wood screw into the hole in the “olive” and then levered it out with a set of dykes.