Homemade Parts!

PB Forum :: Mechanics' Lounge
Homemade Parts!
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Posted: Jan 25, 2020 at 10:26 Quote
Think about it for a moment....
As the piston in the IFP has no piston rod, you can't have any significant pressure difference, between the wet and the dry side, no matter what the gas pressure is.
It requires a mechanical force on the piston, that is driven by something other than the gas or the oil, for a pressure difference over the piston to occour.
That can only happen if the shock is either:

A) Overfilled. Hydraulic locking will be the result of that once the piston bottoms out, and the pressure on the wet side of the piston will get real high, possibly leaking oil to the gas side.

B) Underfilled. The piston will bottom out, making the pressure difference equal the gas pressure, which also will cause leakage, but from the gas to the oil side.

So, for a shock that is not low on oil, the only possible scenario is that the air was there all along.
I'd still put my money on that the shock was low on oil, which happens more often than not, even straight out of the box.


Magura Smile

Posted: Jan 26, 2020 at 12:46 Quote
Are we sick of suspension gadgets yet? Looks like this is my next scheme: Hand dyno. Won't give me a printed graph with numbers and lines on it, but this should at least be a little less time consuming and clumsy than remounting the shock in the bike and bouncing around the shop to see if the damper is working. I've never tried one, but from what I'm reading they're supposed to give you a better feel for damper function than bike bouncing in the shop does. The commercially available model I was looking at costs $1k. It's beautifully made and I'd even say it's worth the money if you have that kind of cash laying around, but I don't. What I DO have is a free license on Fusion360 and a kick ass machine shop with good rates...
Here comes the next gadget... Started looking into hand dynos the other day and only found one priced at 1k. It was beautifully made but I don t need beautiful and expensive. Modeled my own in Fusion360 this morning. Pretty sure my local machine shop will do it for a lot less than 1k...

Posted: Jan 26, 2020 at 13:50 Quote
I used a similar DIY contraption as well. It doesn't really give you much info about the shock setup, but what it does beautifully, is testing for oil leaks and trapped air.

Magura Smile

Posted: Jan 27, 2020 at 20:30 Quote
RunsWithScissors wrote:
More of a homemade tool than a homemade part, but this seems like the kinda crowd that might find it useful, so I'll drop the idea here in case it comes in handy for someone else...

I've been getting deeper and deeper into shock work and needed a vacuum fill and bleed rig for piggyback shocks like Float X. Looking at the price of the "Andreanni Machine" made me choke and start thinking there had to be a cheaper way. Turns out there is. Hand operated vacuum pump, a tee, a couple of ball valves, a big syringe and we're on our way. Tried it today for the first time and it worked like a charm. Total cost of the parts was about $150 vs. a few thousand for an Andreanni Machine.

ITWORKS ITWORKS ITWORKS My hand operated vacuum fill and bleed rig turned out to be a raging success. After pulling a vacuum and filling with oil it only took about a dozen cycles of the damper before all the bubbles were gone and this Float X was dead silent in operation. Yay
Huh this is very cool. Think I'm gonna have to make one of these!

Posted: Jan 28, 2020 at 5:53 Quote
wrote:
wrote:
You can totally do this at home. It's not hard at all. Just jump on Amazon and give Jeff Bezos your money Wink
ITWORKS ITWORKS ITWORKS My hand operated vacuum fill and bleed rig turned out to be a raging success. After pulling a vacuum and filling with oil it only took about a dozen cycles of the damper before all the bubbles were gone and this Float X was dead silent in operation. Yay
Huh this is very cool. Think I'm gonna have to make one of these!

Posted: Jan 28, 2020 at 6:05 Quote
For vacuum bleeding machine I would recommend you to buy vacuum pump (something like that one https://www.aliexpress.com/item/32302256824.html?algo_pvid=afde1b36-b65f-47e1-8079-832967f5705d&algo_expid=afde1b36-b65f-47e1-8079-832967f5705d-1&btsid=55ce6361-a677-4e3f-8a78-0d72d3f65b76&ws_ab_test=searchweb0_0,searchweb201602_3,searchweb201603_52) - it is faster than hand operated.

I have mine DIY vacuum bleeding system similar to http://www.shockbleeder.com/products/shock_bleeder_kits and alltogether it was around 200 € (100€ vacuum pump + 100 € water filter, pressure gauge, brass fittings, tubes....).

I use it for rear shock bleeds and also for Charger dampers.

Posted: Feb 15, 2020 at 23:47 Quote
That shockbleeder is ridiculous. I made something similar myself "almost" for free:
Dyad bleeding

Posted: Feb 16, 2020 at 4:30 Quote
romphaia wrote:
That shockbleeder is ridiculous. I made something similar myself "almost" for free:
Dyad bleeding

After seeing so many different varieties of homemade bleed/fill rigs I'm surprised anyone can sell the high dollar commercially made ones. There's gotta be at least 10 different ways you can do this without spending a crap load of money.

Posted: Feb 23, 2020 at 12:38 Quote
Will this design of crowns allow me to properly tighten the headset?

Posted: Feb 23, 2020 at 12:55 Quote
przecinak wrote:
Will this design of crowns allow me to properly tighten the headset?
Only if you have some other way to adjust the headset besides moving the 2 crowns.

Posted: Feb 23, 2020 at 15:07 Quote
If the angle was set for your specific headtube length with headset stack etc factored in it will work. But if anything changes or your measurements are off even a small amount crowns wont line up correctly.

Posted: Feb 23, 2020 at 19:53 Quote
przecinak wrote:
Will this design of crowns allow me to properly tighten the headset?

No, you will not even have enough adjustment, to take up the tolerances.


Magura Smile

Posted: Feb 23, 2020 at 22:06 Quote
You could maybe use something similar to the system on the OneUp stem to preload the headset

Posted: Feb 24, 2020 at 9:29 Quote
You could have a sleeve that is used to preload the headset allowing the crowns to stay in a set position.

Posted: Mar 14, 2020 at 0:10 Quote
Spangoolies wrote:
skerby wrote:
That's the coolest bike bag I've ever seen. Clean bends and brazing, love it.

Thanks! I made it with a load of scrap I had left lying around in the shed. Made the wheels out of some window frame sections and my old skate wheels. Pretty happy with the result. Both axles lock into the frame so the bike reinforces the bag and doesn’t move at all. Best part is the whole bag weighs just under 8kg and only cost me an extra £20 in fittings. Already had the crappy old bag that i used for a car boot liner.

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