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car valve springs in cell : )

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#1 MessiToM

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Posted 11 October 2012 - 08:35 PM

Can you have to stiff a spring on your collimation bolts? I ask because Iam using valve springs from a leftover engine head's valvetrain in my project. I thought it was a neat idea.

#2 Happy-Idiot

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Posted 11 October 2012 - 08:41 PM

Would tightening the bolts be considered a valve lash adjustment or collimation? Let us know how it works, good idea.

#3 MessiToM

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Posted 11 October 2012 - 08:44 PM

Posted Image

Works so far

#4 Pinbout

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Posted 11 October 2012 - 09:12 PM

if you want to use springs on your collimation bolt, don't use them on the teeter totters.

#5 hottr6

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Posted 11 October 2012 - 10:02 PM

Can you have to stiff a spring on your collimation bolts? I ask because Iam using valve springs from a leftover engine head's valvetrain in my project. I thought it was a neat idea.

My gut tells me it waaaaay overkill. Valve springs have rates measured in hundreds of lbs; Mirror cells need only rates measured in 10s of lbs.

You'll need really strong fingers to collimate.... made even tougher with cold fingers at night.

#6 MessiToM

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Posted 11 October 2012 - 10:10 PM

O overkill for sure! I just wanted to tie in my other hoby (building engines) somehow in this scope build and thought it was clever.

Very good point about tuff collimation with cold fingers.

#7 cheapersleeper

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Posted 11 October 2012 - 10:36 PM

Can you have to stiff a spring on your collimation bolts? I ask because Iam using valve springs from a leftover engine head's valvetrain in my project. I thought it was a neat idea.

My gut tells me it waaaaay overkill. Valve springs have rates measured in hundreds of lbs; Mirror cells need only rates measured in 10s of lbs.

You'll need really strong fingers to collimate.... made even tougher with cold fingers at night.


I agree that valve springs may be too much, but I do think that the stiffest springs that allow you to turn the knobs are the best way to go regardless of whether it is cold or not. Much better to have too much than too little tension. As mirrors get bigger and heavier we have to make sure that regardless of the orientation of the optical tube, the springs are strong enough not to compress. If it's hard to turn the collimation bolts, use a bolt with a bigger head.

Regards,
Brad

#8 ausastronomer

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Posted 11 October 2012 - 11:52 PM

This will be the only amateur scope, I know of, that you will need a torque wrench or rattle gun to collimate :)

Cheers

#9 John Carruthers

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Posted 12 October 2012 - 03:02 AM

I've used bike valve springs in a cell, and old mower motor springs. The strongest I've used were the inner coils from Cooper S blue double valve springs (70 lb/inch)the red ones (90lb/inch) were just too much.

#10 JasonBurry

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Posted 12 October 2012 - 06:26 AM

A friend has Fiat valve springs on his 13.5" cell. Works well, but stiff to adjust.

I'd rather have too strong a spring installed than too weak.

J

#11 Jon Isaacs

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Posted 12 October 2012 - 07:57 AM

The springs in my 12.5 inch Novak cell are quite stiff and there is a pair each bolt. I suspect they are similar in stiffness to a valve spring. The main thing is that cell needs to be able to handle the springs..

#12 Pinbout

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Posted 12 October 2012 - 08:34 AM

with the spring under the teeter totter/collimation bolt, you will always have collimation issues as you rotate thru the alt axis, from zenith to horizon. :o

#13 MessiToM

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Posted 12 October 2012 - 10:40 AM

Well that's unfortunate ^

#14 Gastrol

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Posted 12 October 2012 - 02:44 PM

This will be the only amateur scope, I know of, that you will need a torque wrench or rattle gun to collimate :)

Cheers

...and a feeler gauge... :lol:

#15 jgraham

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Posted 12 October 2012 - 03:43 PM

I think that I'd go with a push-pull system before using springs with this much force. But, to each their own...

#16 Ed Holland

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Posted 12 October 2012 - 04:58 PM

Surely, springs from a Nova would be most appropriate...

:brick:

#17 Binojunky

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Posted 12 October 2012 - 05:28 PM

Not wishing to kill a scope builders jest for the hobby but just once in a while things get a bit silly, car valve springs of all things, not needed and a crazy way to go,JMPOV,DA.

#18 MessiToM

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Posted 12 October 2012 - 05:54 PM

What's it gona hurt? Other than my thumbs possibly ^

#19 MessiToM

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Posted 12 October 2012 - 06:26 PM

Surely, springs from a Nova would be most appropriate...

:brick:


Nope, just mopar springs here lol

#20 kfrederick

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Posted 12 October 2012 - 06:31 PM

I used valve springs on my 20 newt. I built it in 1992. A 3/8 bolt compress them easy. It holds alignment very good the mirror weighs 50 lbs .A weaker spring I think would not be as good .I put them on a plate not on the cross bars of the cell.

#21 TxStars

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Posted 13 October 2012 - 05:45 PM

I see no problem with some grade 8 bolts & all metal parts to prevent wear.

#22 Jeff Porter

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Posted 14 October 2012 - 08:41 AM

I like it. You could then add an old Mercedes hood ornament as a finder.

-Jeff p

#23 MessiToM

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Posted 14 October 2012 - 12:25 PM

lol

#24 bremms

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Posted 14 October 2012 - 12:52 PM

I still have some inner valve springs from a Fiat X1/9 they would work well with a fine thread bolt. It wouldn't take that much to compress them if you oil the threads and use a nice knob.

#25 careysub

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Posted 14 October 2012 - 06:58 PM

A friend has Fiat valve springs on his 13.5" cell. Works well, but stiff to adjust.

I'd rather have too strong a spring installed than too weak.

J


Hmm... how strong does a spring to be so that is not too weak?

Lets say a mirror+cell weighs 30 lb and is supported by 3 springs. Pointed at the zenith, 10 lb of weight compresses each spring, then we want the collimation bolts to pull the spring down further, to create enough force to hold it securely against the bolt. I'm guessing that another 10 lb of force, the equivalent of 1 G holding it against the bolt would be more than adequate. If you treat that as the top of your collimation adjustment range, you will want to pull it down further, a quarter-inch maybe (and have a total 1/2 inch adjustment range)?

So a spring that has 1/2 inch of travel left with a 20 lb load would be about right, wouldn't it? Say a rate of 20 lb/inch and 1.5 inches of working length, or a 40 lb/in rate and a 1 inch working length.

Why would a spring need to be stiffer than that (adjusting for the mirror weight)?






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