Hey guys,
Today I have a question on the types of nuts/bolts for CF flanges. I dont have any access to any hardware store which sells CF flanges hardware so please bear with me for a few simple questions.
I'll use Lesker website as a reference: http://www.lesker.com/newweb/menu_flang ... &init=skip
1. What is the difference between the clearance Flange and the Tapped Flange ? (Please provide some example where it might be use)
2. What is the advantage of bolts that are made of Aluminium, Stainless Steel and the one that is Silver Plated ?
3. What is the difference between Matrix Hex Head and SI Hex Head ? (I'm assuming that it's just the head of the bolts)
Thanks guys for always giving me advice. I have already planned out most of the component of my fusor which would , hopefully, be completed by February 2013. =]
Sincerely,
Jack Puntawong
Types of nuts/bolts for CF flanges
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Jack Puntawong
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Chris Bradley
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Re: Types of nuts/bolts for CF flanges
Jack Puntawong wrote:
> 1. What is the difference between the clearance Flange and the Tapped Flange ? (Please provide some example where it might be use)
A tapped flange is one where the thread does not run through the full width of the flange. For example, a flange to accept a viewport would be a tapped flange. You put studs into a tapped flange and then bolt on the mating flange. I presume the clearance flange (I've not heard that term, actually, but seems to make sense to assume) is a flange with through-holes.
> 2. What is the advantage of bolts that are made of Aluminium, Stainless Steel and the one that is Silver Plated ?
Stainless are the strongest and most resistant. Al is cheaper, should do the job mechanically but may be unsuitable depending on the substances it may come into contact with. Nickel plated brass is mechanically less robust but non-magnetic whereas zinc plated steel are tough and cheap. Plated threads may shed some of their plating during mechanical tightening (especially repetitive tightening), so if that might be a critical issue then it might need to be monitored, but is normally a non-issue.
For repetitive tightening and dis-mounting, use a solid washer and nut. If you repetitively screw a plated bolt and washer, some of the plating will likely find its way into the thread and jam the nut. (I broke two KF flange clamps because of this, so now I regularly clean the threads off of the bolts on clamps. When it happened the first time, I thought it was odd but just chucked it. When it happened a second time, I realised this was what had happened, got miffed, and have made sure not to let it happen again!!)
> 3. What is the difference between Matrix Hex Head and SI Hex Head ? (I'm assuming that it's just the head of the bolts)
'Metric' head, I think you mean. Not sure, but I guess both are the same and refer to ISO standard threads (in mm). I suppose it might mean that 'SI' have iso threads whereas 'metric head' might be intended to mean a non-ISO thread but with a metric hex size? It doesn't really matter much what bolts you use (except for the tapped flange, of course - there you will need the right thread). So long as the bolt fits, you can use it because it is just 'a bolt' through a regular flange and is there to clamp the flange. Shouldn't matter what the thread is, then, so long as it is a suitable diameter.
> 1. What is the difference between the clearance Flange and the Tapped Flange ? (Please provide some example where it might be use)
A tapped flange is one where the thread does not run through the full width of the flange. For example, a flange to accept a viewport would be a tapped flange. You put studs into a tapped flange and then bolt on the mating flange. I presume the clearance flange (I've not heard that term, actually, but seems to make sense to assume) is a flange with through-holes.
> 2. What is the advantage of bolts that are made of Aluminium, Stainless Steel and the one that is Silver Plated ?
Stainless are the strongest and most resistant. Al is cheaper, should do the job mechanically but may be unsuitable depending on the substances it may come into contact with. Nickel plated brass is mechanically less robust but non-magnetic whereas zinc plated steel are tough and cheap. Plated threads may shed some of their plating during mechanical tightening (especially repetitive tightening), so if that might be a critical issue then it might need to be monitored, but is normally a non-issue.
For repetitive tightening and dis-mounting, use a solid washer and nut. If you repetitively screw a plated bolt and washer, some of the plating will likely find its way into the thread and jam the nut. (I broke two KF flange clamps because of this, so now I regularly clean the threads off of the bolts on clamps. When it happened the first time, I thought it was odd but just chucked it. When it happened a second time, I realised this was what had happened, got miffed, and have made sure not to let it happen again!!)
> 3. What is the difference between Matrix Hex Head and SI Hex Head ? (I'm assuming that it's just the head of the bolts)
'Metric' head, I think you mean. Not sure, but I guess both are the same and refer to ISO standard threads (in mm). I suppose it might mean that 'SI' have iso threads whereas 'metric head' might be intended to mean a non-ISO thread but with a metric hex size? It doesn't really matter much what bolts you use (except for the tapped flange, of course - there you will need the right thread). So long as the bolt fits, you can use it because it is just 'a bolt' through a regular flange and is there to clamp the flange. Shouldn't matter what the thread is, then, so long as it is a suitable diameter.
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Jack Puntawong
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Re: Types of nuts/bolts for CF flanges
Thanks Chris for such a quick reply. I think I will go with Stainless steel bolts through out the chamber from the looks of the shipping price. (Better to be as resistance as possible to avoid another order). The stainless steel bolt is the most flexible and durable I presume. By the way, do you use the viton o-ring for the KF flange ? Does it withstand the temperature that the fusor produce?
Jack Puntawong
Jack Puntawong
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Chris Bradley
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Re: Types of nuts/bolts for CF flanges
yes, the shipping is usually the bigger cost factor in the bolts than the bolts are, so just buy the better quality, and I would agree the SS is by far the better quality. There are also different grades of SS. Outside the US, these are usually referred to as 'A2' or 'A4'. Both would be quite suitable for your purpose, the A4 being acid resistant so you should find it a bit more expensive. The A2 is usually sold as A2-70 (meaning a tensile strength of 700MPa, so clearly an A4-80 would be meaning a 800MPa strength). You'd have to check your local nomenclature if the bolts are not marked A2 or A4 - there will be some SAE grade in the US, easily looked up on the internet. But it is essentially immaterial as either will do, just buy the cheapest SS grade.
In regards seals for fusors, I do not run a conventional fusor but I can be sure that you don't want anything 'hot', nor plasma, getting close to your rubber seals. Viton is better for the lower vacuums, but nitrile (buna) is absolutely, completely fine for the unit-odd micron pressures of a fusor and should be considerably cheaper. I believe it is also more resistant to adsorbing water vapour than viton too, as it happens.
If you have areas where plasma is likely to approach a rubber seal then shield it closely with a grounded metal screen and this will help avoid penetration of the plasma to it. You will probably find that this is already accomplished by the way the flange comes together. If you buy centring rings for KF flanges, for example, they will come with an inner metal ring that holds the seal in place, whereas for CF types they will come together close enough that it is unlikely plasma will reach into the crevice. The CF are designed for metal seals, so if you get a 'rubber' replacement then, I presume (not used them myself) the dimensions will have been chosen with this in mind - but worth checking for yourself for your own confidence. The heat from the shell itself should not be a concern to the seals as they should be fine for over 100C and if you get your shell to that sort of temperature then you've probably other concerns before the seal's temp resistance.
In regards seals for fusors, I do not run a conventional fusor but I can be sure that you don't want anything 'hot', nor plasma, getting close to your rubber seals. Viton is better for the lower vacuums, but nitrile (buna) is absolutely, completely fine for the unit-odd micron pressures of a fusor and should be considerably cheaper. I believe it is also more resistant to adsorbing water vapour than viton too, as it happens.
If you have areas where plasma is likely to approach a rubber seal then shield it closely with a grounded metal screen and this will help avoid penetration of the plasma to it. You will probably find that this is already accomplished by the way the flange comes together. If you buy centring rings for KF flanges, for example, they will come with an inner metal ring that holds the seal in place, whereas for CF types they will come together close enough that it is unlikely plasma will reach into the crevice. The CF are designed for metal seals, so if you get a 'rubber' replacement then, I presume (not used them myself) the dimensions will have been chosen with this in mind - but worth checking for yourself for your own confidence. The heat from the shell itself should not be a concern to the seals as they should be fine for over 100C and if you get your shell to that sort of temperature then you've probably other concerns before the seal's temp resistance.
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Richard Hull
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Re: Types of nuts/bolts for CF flanges
Most smaller flanges 2.75" conflats, etc., can use, common, very inexpensive 1/4 X 20 steel bolts and related hardware. Though most of the pro-stuff uses the common N.F. threading 1/4 X 28.
It is an expensive and needless measure to purchase any other special flange related hardware.
Larger flanges can used common 5/16 X 16 steel hardware and so on.
No need to get all tangled up with needless expense.
Richard Hull
It is an expensive and needless measure to purchase any other special flange related hardware.
Larger flanges can used common 5/16 X 16 steel hardware and so on.
No need to get all tangled up with needless expense.
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
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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John Futter
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Re: Types of nuts/bolts for CF flanges
Jack
It is impportant to use silver plated stainless bolts in CF flange tapped holes.
Stainless has a nasty habit of picking up on threads. Ie the threads mysteriously weld themselves together ruining the the flange. The silver acts as a lubricant. Even if using ordinary steel bolts in the threaded flange it is a very good idea to coat the bolt with anti seize such as nickel or copper loaded grease.
It is impportant to use silver plated stainless bolts in CF flange tapped holes.
Stainless has a nasty habit of picking up on threads. Ie the threads mysteriously weld themselves together ruining the the flange. The silver acts as a lubricant. Even if using ordinary steel bolts in the threaded flange it is a very good idea to coat the bolt with anti seize such as nickel or copper loaded grease.
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Peter Schmelcher
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Re: Types of nuts/bolts for CF flanges
I got a few used CF parts that came bolted together with a small amount of anti seize grease on the threads. An alternative might be Teflon plumbers tape.
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Jerry Biehler
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Re: Types of nuts/bolts for CF flanges
Teflon cold flows right out of the pressure area so it really does not do much.
I have had less galling with the finer pitch hardware. You can use anti-sieze, but it can be a bit messy. The silver plating is nice, it really comes into play when when you heat up a system to bake it out.
I have had less galling with the finer pitch hardware. You can use anti-sieze, but it can be a bit messy. The silver plating is nice, it really comes into play when when you heat up a system to bake it out.
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Richard Hull
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Re: Types of nuts/bolts for CF flanges
The use of N.F. thread, SS hardware with anti sieze compound is fine for pro systems that are going to be heat cycled via bakeout over and over again, but for the common amateur fusor, old fashion, hardware store, coarse threaded steel with lock washers is all that's needed. Few, save the perfectionist fusioneer ever bakeout, fully built, in-place systems.
The wise, and most fusioneers, just make sure stuff is clean and degreased when assembled and then just vacuum the entire thing out until an acceptable vacuum is produced and work solely in a technical and not a scientific vacuum.
Richard Hull
The wise, and most fusioneers, just make sure stuff is clean and degreased when assembled and then just vacuum the entire thing out until an acceptable vacuum is produced and work solely in a technical and not a scientific vacuum.
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
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
Re: Types of nuts/bolts for CF flanges
Automotive copper loaded antiseize compound is sold here in the UK as "Copper Slip" and is used on the bolts that hold brake components together and wheel studs in due to the fact that they have a tendency to weld themselves together from combined pressure and heat.
So a garage or place that sells car parts may be able to supply you with anti seize copper loaded grease. I guess you might want to be careful not to contaminate anythign with it that will end up inside your chamber.
An alternative in a pinch is to copper plate the threads of the bolt using a battery, copper sulphate solution and a second electrode made from copper (Copper pipe maybe ??). This is realitvely easy if the bolt is chemicaly clean and can be readily redone when it wears if you redo the bolt much.
Copper sulphate (If your chemists don't sell it anymore) is usualy used as an anti fungal application in gardening and fruit growing. Plant Nurserys use it also for getting seedlings etc started faster than fungus can take them down.
Copper plating may reduces the risk of getting grease where you don't want it.
So a garage or place that sells car parts may be able to supply you with anti seize copper loaded grease. I guess you might want to be careful not to contaminate anythign with it that will end up inside your chamber.
An alternative in a pinch is to copper plate the threads of the bolt using a battery, copper sulphate solution and a second electrode made from copper (Copper pipe maybe ??). This is realitvely easy if the bolt is chemicaly clean and can be readily redone when it wears if you redo the bolt much.
Copper sulphate (If your chemists don't sell it anymore) is usualy used as an anti fungal application in gardening and fruit growing. Plant Nurserys use it also for getting seedlings etc started faster than fungus can take them down.
Copper plating may reduces the risk of getting grease where you don't want it.