Having parts machined
Yes, just provide a drawing to a local engineering fabrication firm and they will sort you out.
If you aren’t fully clued up on tolerancing etc. it would probably be worth speaking to them about it so they understand what you are going to achieve.
They can probably also advise on how to draw something up that minimises cost.
Obviously the tighter tolerances are the the more expensive the part will be.Posted 5 months ago
Do you know what material you want to use?TheBrickMember
If you know someone that works that works at an engineering firm this is best as loads of places slow a little homework out of hours that someone will do for a bit of cash over lunch.
Ask around your mates as someone may not be a machinest but may work with some.
If you are based anywhere near Bournemouth i could maybe help depending on details as we have a full machine shop at work.Posted 5 months ago
This is the air spring – it sits inside that large bronze coloured cylinder, but in this case the bottom has been popped out so you can see:
What I want to do is replace that internal shaft to one with holes in different places. Normally the end cap (the bit with the air valve in it) is bonded (I think) to the shaft, but I happen to have an end cap lying around that has no shaft.
So I would need a shaft of the right external diameter, and then a piece made to fit into the end cap with a flange to accept the end of the shaft, which I’d then glue into place in the end cap. I then drill my own air hole in the end of the shaft. This allows me to bin that floating piston thing and then pressurise the negative chamber by means of the valve. Currently it’s a self-setting thing by means of that notch you can see in the shaft. And it’s not enough -ve air I think.Posted 5 months ago
Well I’d imagined starting off with a piece of tube that’s already a tube, and simply turning it down to reduce the outside diameter. Internal diameter doesn’t matter. The air hole I mention is just a hole in the side of the thing, which I’d do with my own pillar drill.Posted 5 months agomick_rSubscriber
Not sure exactly which bit you want, but that shaft looks to have a very finely machined and hard anodised finish – not just a bit of ally bar chucked in a lathe. And as dovebiker suggests long / deep small diameter accurate holes are a specialist thing (not always made with a drill).
Have you found any suitable raw tube listed anywhere?
Is there going to be a sliding seal surface on your new shaft (which is the bit requiring the fancy surface finish)?Posted 5 months ago
Depends if you can start with a tube that’s a standard size. It could be non standard. If you can measure the tube and check on line to see if it’s a standard size. If it’s not you’re looking at making a tube from rod.Posted 5 months ago
I would guess it is a standard size, but worth checking.
But the only accurate bits are external diameter – the internal dia and the extra hole in the end don’t matter. Surely it’s just a question of taking an off the shelf tube and turning it down?
The external finish is the bit that I would imagine would be hard. Possible to either not bother and just have a rough finish, or anodise it myself.
Of course if it’s a standard tube size I’d just have to have a piece made to fit it to the end cap.Posted 5 months ago
I’m curious as to why you’re doing this? Is something broken?
No, just not quite right still. The -ve pressure isn’t adjustable, and I want to add more. The mod will work if I can make it.
If I can buy a bit of tube and have a thing machined for a reasonable number of pounds then it’s worth a shot. And it’d be a satisfying project.
Is that a windy-down marz 66 I see before me? Thought I had the last of those
Mine doesn’t wind down, I had that fixed under recall. It’s always annoyed me though – loads of stiction. So I’m thinking about this mod, also going to see if I can replace the double Marz seal with a single Rockshox one and foam ring. Maybe also Fox Green oil …Posted 5 months ago
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