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m1tanker78
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[*] posted on 27-3-2012 at 15:07
Correct clamp for the job?


I'm embarrassed to ask..

I recently swallowed my pride and decided to order some 'real' glassware for distillations, refluxing, etc. I'm also going to purchase an assortment of stands, clamps, clips, thermometers and so on. I'm a little confused with the different types of clamps that are available.

For example, there are simple clamps that look like this, ( )...
And others with 3 or 4 fingers.

Which is better for supporting the heating flask (say, a 1L 3-neck RBF) and which is appropriate to hold the condenser?

Are all lab thermometers manufactured to a standard thickness??


I appreciate any advice you all can share. This is all new to me and I don't want to break anything before I've gotten good use out of it. I certainly don't want to put my safety in danger although I'll be easing into this with water distillations using sand, oil, and possibly metal beads for heating on an electric hot plate.

Thanks,

Tank




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peach
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[*] posted on 28-3-2012 at 02:06


The style of clamp is less important (in my opinion) than learning where to clamp things and how tightly.

The word 'clamp' implies gripping the thing tightly, but that is usually not the best of ideas. Particularly if more than one clamp is involved. The clamps are not precision machined or auto-aligning. They will move when each of the screws is done up. If they're already tight up against something that's clamped elsewhere, they'll try to bend the thing in the way (the glass, which doesn't bend).

In general, thermometers are all around the same diameter, unless they're made for a special application (e.g. precisely measuring room temperature over a small range for calibration conditions).

[Edited on 28-3-2012 by peach]
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Hexavalent
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[*] posted on 29-3-2012 at 11:14


I can attest to Peach.

In my experience, the 4-finger ones, such as



seem to work the best, being rugged, stable and comparatively cheap, fitting many/most different types of glassware. The cork or plastic lining does become eroded after several years, but then the clamps have a further use, as plain metal ones, for high-temp operations. Personally, my clamps are over 20 years old and the cork is still perfect on them, though. They are as sturdy as ever, and I use them on a very regular basis.

With these, though, you do also need Bossheads;



although these do have many other uses in the lab, such as holding eyelets and other items, supporting rubber tubes or large cables, weighing down condenser water return tubes into buckets to stop them spraying everywhere, etc etc.

As Peach also said, though, proper clamping and positioning of those clamps *is* much more important than the clamps themselves. Try testing your clamping instinct very well on cheaper glassware, such as small tubes or erlenmeyers, before trying to fit in standard taper stuff or other expensive glassware such as burettes.

You may, however, find a single thermometer clamp occasionally useful;


, particularly for supporting thermometers in hot oil/water baths, in large glassware such as 600ml/1L beakers, etc.





[Edited on 29-3-2012 by Hexavalent]




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[*] posted on 29-3-2012 at 12:02


I much prefer my 3-fingered, 2 screw clamps over my single screw clamps. The 2 screws allowed finer and easier adjustments without moving the glassware.



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Hexavalent
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[*] posted on 29-3-2012 at 12:24


Where can one obtain those in the UK, Magpie?



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[*] posted on 29-3-2012 at 12:29


Quote: Originally posted by Hexavalent  
Where can one obtain those in the UK, Magpie?


I have no idea. I obtained my two in a grab bag from eBay. I would like to have a couple more.




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m1tanker78
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[*] posted on 31-3-2012 at 05:48


Thanks for the input. Hex, good call with the bossheads. I hadn't even taken them into consideration. I'll be placing my order shortly!

Should I remove the nylon coating on the clamps and use another material (glass wool?) between it and the flask? I gather that I shouldn't use direct metal to glass contact - especially with heating. Am I correct? I've considered making red RTV 'socks' for this purpose but may be overkill.

Thanks again,

Tank




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[*] posted on 31-3-2012 at 11:45


Glass can contact metal (provided it's being used as a rest), but under no circumstances should you try doing the clamp up.

The most ubiquitous thing on this planet, bar water, is that the padding is burnt off every clamp stand in every secondary school. It gradually dies if you use them on a regular basis. The rest of the clamp stand / lattice can also end up grubby and corroded too.

Chop a bit of tubing to length and slide it over each of the jaws. Neoprene seems to work rather well.

[Edited on 31-3-2012 by peach]
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[*] posted on 31-3-2012 at 13:06


i also got new clamps to replace my old homemade clamps because just when i had all the glass lined up it would all pull every which way when i went to tighten down.i even got real glassware to replace my coffee pots and oil lamp tubes.for the first time i watched the red nitric fumes slowly being pushed away until they almost disappeared when i last distilled nitric. i got two clamps for $7.99 from cr scientific and two aluminum clamp holders for$3.99. i got one really low quality clamp off ebay that is bult like a toy for $15.00. i swear the clamps were dipped in that rubber paint.i use an alihn condensor instead of a graham or liebig and it works just fine. the lab stand can easily be made.

[Edited on 31-3-2012 by cyanureeves]
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[*] posted on 1-4-2012 at 12:44


Quote: Originally posted by cyanureeves  
the lab stand can easily be made


I agree. I once made a very large 'Flexaframe' for the main bench, by strapping some of those super-heavy bricks to the centre of a piece of wood and then drilling holes on either side. Two 1m 11m diameter steel rods were then inserted into the holes and sealed, they costed me £5 each from a local hardware supercentre. I then acquired a job lot of bossheads on eBay, and attached using these and a heavy set of pliers two vertical rods of the same specification as before over the vertical ones.

It is actually very stable and works marvellously for all operations I have attempted so far, including large distillations. A similar setup from a lab supplier would usually cost hundreds of dollars, yet this one seems to work just as well and was much cheaper. In this home-build fashion, the unit can be tailor-made for your bench and if you want somehow affixed permanently to the benchtop.

Of course, I also have some normal lab stands that are movable for work in the fume cupboard and for unusual/awkward setups on the bench. Although I was donated mine from school, it is certain that you could build these also by yourself with half an hour, some wood or brick, a drill, a metal rod and some patience.




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m1tanker78
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[*] posted on 3-4-2012 at 17:38


Great pointers, gents! My glassware came in today - no broken bits (whew!). My other order with the therms, clamps, etc is looking like it's going to take a while to arrive. My free time has been very limited lately but I was able to scrounge though my hardware bins and found out that a 1" counduit hanger fits the 24/40 flasks and condensers perfectly (with wiggle room for padding). I'm going to use some thin red rubber padding between the 'clamp' and the flask. I'll figure something out for supporting the rest when the time comes - if the second order doesn't beat me to the punch. :P

Christmas in April.... :D

Tank




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Hexavalent
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[*] posted on 4-4-2012 at 14:21


Nice, post some photos of your new gear!:)



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[*] posted on 4-4-2012 at 15:12


tank that is what i used for my homeade clamps. i welded them to a steel rod and coated them with red rtv then i ran the other end of the rod through a hinge pin holder that was the same diameter. i welded the hinge to a 1/2 inch thick wall tubing that slid up and down the lab stand rod then tapped and threaded the tubing for the clamp down bolt. THEN i nickel plated the whole thing. all this stuff i learned when i worked heavy fab in your hometown,houston tx. boy you will be so happy when you get your clamps,happy,happy,happy.
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[*] posted on 4-4-2012 at 15:21


Nice one cyan, can you post images of your creations?

One can never have too much nerd porn:)




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[*] posted on 4-4-2012 at 15:36


are you kiddin hex? i was so ashamed of my clamps i think i buried them as soon as i got real ones and i sure as hell could'nt post any pics because i would run the risk of not being taken seriously next time i posted a question.(clothes makes the man sometimes to some people) i made nitric one time with the set up but it was really hard to keep the hold thing steady when i tried to clamp down.
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[*] posted on 4-4-2012 at 23:07


Yea, I'm serious! I admire homemade equipment that offers an alternative to the standard lab variety, it shows skills and inventiveness in the user:)



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[*] posted on 10-4-2012 at 11:59


Hex, I unwrapped the glassware to make sure nothing was broken or missing. I almost immediately wrapped everything back up so no pics yet.

Speaking of pics, I decided to try my hand at making a sturdy stand and here's what I ended up with (after taking a trip to Lowe's):


Not pretty but seems plenty sturdy. :D

[EDIT] All that's left is to attach the jaws to the rod. Something tells me I'll be using this bad boy more than the flimsy stands I ordered (but haven't received). The vertical pipe is a 2.5' length of conduit.

Tank

[Edited on 4-10-2012 by m1tanker78]




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[*] posted on 10-4-2012 at 13:40


Very, very nice. I wish I'd have thought of something like that. What's the bosshead you have on the bottom . . .is that a proper lab one or something you made (brilliant either way)!

IMO, any stand can be made considerably more useful by attaching temporarily to the bottom one or two of those very heavy bricks you get in storage heaters;






their relatively small size and enormous weight add stability to even the flimsiest of stands. I have a few kept in the corner of my lab from when we replaced the heaters in our house for just such purposes . . .I assume you could just go down to a refuse centre and they can provide you with some free of charge.


Best of luck with apparatus building and with your new lab, Hex.


[Edited on 10-4-2012 by Hexavalent]

[Edited on 10-4-2012 by Hexavalent]




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[*] posted on 13-4-2012 at 14:35


Hex: I made the bosshead by welding two of these together:


...and substituted the bolt with a thumb screw(?).

My other order has arrived and just for kicks, I'm including a pic of my homemade stand and one of the cheapies I bought for comparison. I already attached the 'jaws' (conduit hanger) to the threaded rod - all that's left is to take this baby for a spin:


Tank




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[*] posted on 14-4-2012 at 06:43


Quote: Originally posted by m1tanker78  
[...] by welding two of these together:
"Those" things are called beam clamps.
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[*] posted on 14-4-2012 at 10:29


Very nice, Tank. It's amazing how small and puny the commercial one looks next to yor home made one, which visually looks much more stable and steady. Why not post us some more images of your other new gear and glassware? By now I'm sure you've realised that the members of this forum love to drool over nice labware . . .



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[*] posted on 14-4-2012 at 12:05


now get you a fish tank submersible pump and those tube stretch band things used for excercising for your condenser. i like the stand because when i welded the rod to my base i didnt quite square it and heat always tugs on the metal too.good thing the rod only is reference point so all my set up is oriented anyway but you can find stuff at goodwill,like a second hand electric burner.my palm is itching for another arm adaptor cuz for years it was the one thing i could never duplicate with my jerry rigging ingenuity.
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[*] posted on 15-4-2012 at 15:04


Reeves, I already had a submersible pump. I tapped the outlet to accept a standard brass hose barb. I didn't weld any part of my stand except the beam clamps (thanks watson.fawkes) to make the bosshead. The vertical conduit beam slips snugly over a bolt so it can quickly be disassembled for storage.

I ran a simple water distillation today to test the glassware as well as my 'rigging' skills. I bought a 1oz tube of silicone based lubricant and used a small dab on each joint. It seems to have worked beautifully and should be fairly inert to most organics (I hope). Everything held together perfectly - no leaks or defects that I could detect. I used my improvised clamp and my homemade stand. Worked flawlessly! I used one of the commercial stands and a three-fingered clamp to support the Liebig.

Hex, I believe my glassware is made in China - nothing special. Still, I love the way it all looks!

I really appreciate the helpful tips.

Tank




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[*] posted on 15-4-2012 at 16:55


m1tanker78 can you answer a thing for me? knowing you got new glass i know your ground joints are new so i dont know if you have read that glass joints should be coupled by inserting and then given a half turn to firmly grip both glass joints together.i have done this and sure enough i can feel the ground joints grind while i'm turning and come to a stop and form a grip.the grip is even firm enough to lift both apparatuses with either of the glass items alone and wont slip off.when i added joint grease though i could not feel the grit when i gave it the half turn and in actuality could go 360 without even tightening up so i had to use keck clips. my question is do your joints do the same because i know for a fact that some of my glass was used when i got them and thought that maybe new glass would be different. i dont know if old or used glassware may have worn down ground joints enough to leak. i bet i could fill a non ground joint flask with sand and sand blast the inside of the neck and make it a ground joint and do the same to the male end. i have sand blasted before and and have seen glass roughen easily with the blowing sand.

[Edited on 16-4-2012 by cyanureeves]
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[*] posted on 15-4-2012 at 17:46


Reeves: My ground glass joints make a gritty sound (like honing my cut-throat razor on the strop). I didn't try to intentionally 'lock' the joints. When greased, they glide smoothly and go from opaque to transparent. I used Keck clips on all joints from adapter out. Also note that I've seen some people using springs and even rubber bands (for lower temps) to keep everything tight. If you're having trouble with leaks maybe find some suitable springs that are flexible enough to use on your app?

As for sand blasting the joints... You'd probably need to use alumina media (or better) to properly gouge the boro glass. Some of the sand in the flask would undoubtedly get blown out. I'm just speculating here.

Tank




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