conflat vacuum bolts

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Jake Wells
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conflat vacuum bolts

Post by Jake Wells »

i have found these conflat flange bolts on eBay will they fit through a non threaded 2.75 conflat flange bolt hole?
http://www.ebay.com/itm/VARIAN-MDC-STAI ... 8172&rt=nc
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Rich Feldman
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Re: conflat vacuum bolts

Post by Rich Feldman »

Hi Jake.
How much time did you spend investigating that question
using resources other than "just ask at fusor.net" ?
Please try to figure it out by yourself first.
You can get the answer sooner and learn more.

1) We can all see that the ebay vendor says the stainless steal [sic] bolts are used, and are for Conflats, and are 1 1/4 inches long. You can get a pretty good idea of the shank diameter by measuring the photos, or asking the ebay seller.

2) Do different size conflat flanges have different size bolt hole diameters and bolt length requirements?
Just look at some data sheets or vacuum-equipment guides.

[edit] Hint: check out http://vacuumshopper.stores.yahoo.net/4odtube.html
All models are wrong; some models are useful. -- George Box
Jerry Biehler
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Re: conflat vacuum bolts

Post by Jerry Biehler »

Jake Wells wrote:i have found these conflat flange bolts on eBay will they fit through a non threaded 2.75 conflat flange bolt hole?
http://www.ebay.com/itm/VARIAN-MDC-STAI ... 8172&rt=nc
Looks like standard 1/4-28 bolts that should bolt together standard flanges. I tend to used just generic hardware store 1/4" stainless bolts. Do not use steel.
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Richard Hull
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Re: conflat vacuum bolts

Post by Richard Hull »

I have used standard steel, coarse threaded hardware for 100% of my vacuum conflat systems for years. I have also torn apart some professional systems that used the vacuum rated, fine threaded SS bolts that were so badly frozen that they had to be sawed off. For common fusor use, I think common steel hardware is just fine, however, use the expensive stuff if you wish.

Recently I had occasion to remove some vacuum plumbing and had some old SS, 1/4X28 bolts from salvaged stuff so I used that hardware for re-assembly. I tend to use what is at hand and upgrade as I go, provided I have better stuff laying around that I have acquired.

I would not recommend course steel for a pro system assembly, of course. Most fusors are crude affairs by most any standard and are not menat to survive industrial or extended scintific use for many years. I understand a few people want to do a nice professional job and if you have the money for all the pro flanges, go for the pro hardware.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Bob Reite
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Re: conflat vacuum bolts

Post by Bob Reite »

Yes 2.75 inch conflat flanges take 1/4-28 bolts. Stainless steel bolts and nuts from Fastenal and similar places will work fine for non threaded flanges.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
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Andrew Robinson
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Re: conflat vacuum bolts

Post by Andrew Robinson »

Don't waste your money. http://www.mcmaster.com
I can wire anything directly into anything! I'm the professor!
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Andrew Robinson
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Re: conflat vacuum bolts

Post by Andrew Robinson »

Here, look up this part number on McMaster (91271A573)

x50 brand new for $10 and some change.

Fastenal works too.
I can wire anything directly into anything! I'm the professor!
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Richard Hull
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Re: conflat vacuum bolts

Post by Richard Hull »

I have come to not like Mc Master over the years. High postage and other needless charges on smaller orders.

I now just use

http://www.boltdepot.com/catalog.aspx?g ... 7AodGjUA7w

100 - 1/4X20X1.5 316 SS bolts $27.00 (hex head)
same bolt in 18-8 SS 100 for $16.00
same bolt grade 8 steel - zinc plated 100 for $10.00

Unfortunately, if you have pre-threaded CF flanges you are locked into the fine threads.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
John Futter
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Re: conflat vacuum bolts

Post by John Futter »

The correct bolts for threaded CF flanges are either NF thread or metric thread.
Herein lies a huge danger 8mm and 5/16NF are almost identical but the threads bind after 2-3 turns these bolts are what are used 4" CF upwards.

If you have threaded CF componentry and can afford it -use the silver plated stainless steel bolts. The silver is to stop the bolts galling.
If the bolts you use are not silver plated then silver anti-seize compound or nickel anti-seize should be used on the bolts to stop galling.
Do not use copper anti-seize!!
Stainless bolts are renond to seize in stainless threaded holes.
I personally would use zinc plated high tensile steel hardware which will stop the above happening and is much cheaper
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Richard Hull
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Re: conflat vacuum bolts

Post by Richard Hull »

Yes, $10.00 per hundred in 1/4x20X1-1/2 inch length as noted in previous post from bolt depot. I try to avoid pre-tapped CF flanges unless I have one and it is needed due to the inability to suffer a nut on the other side due to spatial considerations. (usually due to poor system design in the first place.)

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Bob Reite
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Re: conflat vacuum bolts

Post by Bob Reite »

To echo what John said, if you have tapped flanges (as I do on some of my parts), bite the bullet and get silver plated bolts. I can't count the number of times I've had stainless steel nuts and bolts gall up on various projects. If you are using through hole flanges, it's not such big deal to just break the bolt off and put in a new one if it galls up.
The more reactive the materials, the more spectacular the failures.
The testing isn't over until the prototype is destroyed.
Jerry Biehler
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Re: conflat vacuum bolts

Post by Jerry Biehler »

Yep, stainless galls if you look at it funny. But with steel it will contaminate the stainless fittings and can cause corrosion issues. There are anti-seazes that help and any lubrication will help too. Once you get a little burr on a thread is is all over with.
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Chris Bradley
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Re: conflat vacuum bolts

Post by Chris Bradley »

Why would it come with a nut if it was a captive thread?

For the life of me, I can't see why a 10 cent regular zinc plated steel bolt won't do. It's not like you should ever take this size of bolt to its torque maximum when clamping up a joint.

This sort of stuff is ideal for a professional lab that has to have everything just-so, and delivered right the first time. If you're kludging together a home-brew bit of kit, you have to use some common sense.
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Richard Hull
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Re: conflat vacuum bolts

Post by Richard Hull »

Some folks with money just like the pro look and even figure nice cap head screws are too plebian and go for the silver plated 12 point bolts. (Wow!). If ya' got th' dough and love that look of "see my money", then go for it.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Jerry Biehler
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Re: conflat vacuum bolts

Post by Jerry Biehler »

Chris Bradley wrote:For the life of me, I can't see why a 10 cent regular zinc plated steel bolt won't do. It's not like you should ever take this size of bolt to its torque maximum when clamping up a joint.

This sort of stuff is ideal for a professional lab that has to have everything just-so, and delivered right the first time. If you're kludging together a home-brew bit of kit, you have to use some common sense.

If you are actually using the stuff for UHV and baking the system out you want stainless. I have so much stainless hardware from all the bits and pieces of conflat I have picked up over the years that I really dont worry about it. Like I said before, steel contaminates stainless and will cause it to start rusting. Only way to stop it is with something like nitric or oxalic acid all the way up to HF.
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Dave Xanatos
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Re: conflat vacuum bolts

Post by Dave Xanatos »

Jerry Biehler wrote:Only way to stop it is with something like nitric or oxalic acid all the way up to HF.
Thanks for that tidbit... I have five pounds of oxalic acid, and was wondering what I'd ever use it for...
It would take decades of work, by thousands of scientists, in a particle accelerator powered by dump trucks of flaming grant money! - Professor Farnsworth/FUTURAMA
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