The Triumph Dolomite Club - Discussion Forum

The Number One Club for owners of Triumph's range of small saloons from the 1960s and 1970s.
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PostPosted: Fri May 10, 2024 9:53 pm 
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There's a lad at work here who's mad about 3d printing....if someone can supply a fag packet sketch I could ask him about getting some made perhaps.
It's more complex a casting than a fag packet sketch.....!
Which bit are we talking about on here?....

Image

I've never seen inside a servo before!

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PostPosted: Fri May 10, 2024 10:15 pm 
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What does the Bakerlite look like.

You say you tried Alloy.
Is Steel a option.
Be much more hard wearing that Alloy.


I can asked my Engineer/ Machinist's if that’s helps. I

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2009 Mini Clubman Cooper S Daily Driver.
1980 Dolomite Sprint with a touch of BLTS
Balanced Lightened and Tweaked 13B Rotary and SuperCharged.
Back in my possession 22 September 2019.
Rebuilding the Sprint time taken so far, 111Hrs@15/12/2020
212Hrs @31/12/2021
352 @ 28/11/2022
455Hrs @ 20/10/2023
530. @ 09/07/2024
This is time taken at the Sprint not necessary time worked.

Member TDC no 0471

Project 13B Sprint now back on..
No Pistons No Cams how’s it gonna run?


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PostPosted: Sat May 11, 2024 9:02 am 
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Bakelite is the material pre-war light switches and door handles used to be made of, often mottled brown in colour; a bi-product of the coal industry, I believe.

One of the Ford owners commissioned a piston to be machined from steel billet; it cost him £500 apparently, but when he gave it to the reconditioners to put into his servo they found it was too heavy for the limited manifold depression to move it back and forward.

The issue with the light alloy version is a 3 mm slot needs to be milled into the centre shaft, but the resulting thin wall it creates keeps bursting before the slot is completed. They're looking at whether reinforcing the wall would be detrimental to other operation of the servo...and I've suggested they might move the split between the two cast parts to the slot location so that when they then TiG together the slot is created by a machining in one part prior to mating them together...

Work in progress...


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PostPosted: Sat May 11, 2024 9:14 am 
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Do you have any pictures of the bakerlite component.

Could it be made in two pieces.
Steel insert with a the outer in alloy.

Would Titanium be a viable option if a steel insert was possible.
Light but expensive

What grade of alloy are they trying.

_________________
2009 Mini Clubman Cooper S Daily Driver.
1980 Dolomite Sprint with a touch of BLTS
Balanced Lightened and Tweaked 13B Rotary and SuperCharged.
Back in my possession 22 September 2019.
Rebuilding the Sprint time taken so far, 111Hrs@15/12/2020
212Hrs @31/12/2021
352 @ 28/11/2022
455Hrs @ 20/10/2023
530. @ 09/07/2024
This is time taken at the Sprint not necessary time worked.

Member TDC no 0471

Project 13B Sprint now back on..
No Pistons No Cams how’s it gonna run?


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PostPosted: Sat May 11, 2024 11:24 am 
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Location: Harrow Middlesex
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It's more complex a casting than a fag packet sketch.....!
Which bit are we talking about on here?....

Image

I've never seen inside a servo before!

Image
Its an odd shape i can see why your have trouble making it, another option could behave it sand cast make the wall thicker cut the 3mm slot then remachine wall back down if you need to, as you say Brass or ally could be used

if you need help there a sand cast place near me

Dave


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PostPosted: Sat May 11, 2024 12:00 pm 
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Location: Over here...can't you see me?
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Do you have any pictures of the bakerlite component.

Could it be made in two pieces.
Steel insert with a the outer in alloy.

Would Titanium be a viable option if a steel insert was possible.
Light but expensive

What grade of alloy are they trying.
It seemingly has to be made in two pieces, hence the TiG weld prior to final machining. I've no idea what grade they're using, just reporting what I'm told at each update. I don't have a picture to hand. Mart took one away that had been cut in half and made a CAD model of it...
Quote:


Its an odd shape i can see why your have trouble making it, another option could behave it sand cast make the wall thicker cut the 3mm slot then remachine wall back down if you need to, as you say Brass or ally could be used

if you need help there a sand cast place near me

Dave
It's in the hands of the reconditioners who I use who have external expert contacts they use regularly for casting, machining, 3d printing etc. I'm not involved beyond the expression of interest I've made that the Club would provide them with more custom beyond the Ford models if they're successful...


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PostPosted: Sat May 11, 2024 2:07 pm 
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Here you go...

Image

Image

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Sprintless for the first time in 35+ years. :boggle2: ... Still Sprintless.

Engines, Gearboxes, Overdrives etc. rebuilt. PM me.


1997 TVR Chimaera 450


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PostPosted: Sun May 12, 2024 11:03 am 
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I am not sure about this particular component but some Bakelite can contain asbestos.


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PostPosted: Sun May 12, 2024 4:54 pm 
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Old servo rattles when I shake it. Guess that’s fairly conclusive that the Bakelite piston has broken !!


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PostPosted: Sun May 12, 2024 8:08 pm 
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Unfortunately, yes


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PostPosted: Mon May 13, 2024 4:57 pm 
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I am intrigued by what function the Bakelite disc performs inside the servo.
Its not a strong enough material to be subjected to full brake pressure so looking at the pictures above it may be some kind of support/former for the rubber diaphragm?

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Russ Cooper
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