MadModder
Gallery, Projects and General => How do I?? => Topic started by: John Hill on July 16, 2009, 05:12:22 PM
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I am considering machining plates by bonding them to a holding piece with instant glue the theory being that moderate heat will release them?
These are the side frames for my little nutating engine which really need to be nicely cleaned up more than I could easily do with abrasives etc.
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Hi John
Yes heat will release supper glue (can't spell cyanoacrylate) I've used this method myself for holding thing whilst machining the biggest problem with it is that its a bit brittle and the bond can crack so you have to take really small cuts and feeds, if you can get hold of some two sided sticky tape that may work better, or try using a combination of glue and some form of mechanical fixing.
Old clockmakers use to use a thing they called a shellack chuck similar idea to using glue.
Hope this helps
Stew
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John,
If you look at it technically, ali is a very difficult material to 'stick' together. It forms it's own oxide coating in a matter of seconds after the original oxide layer is penetrated, it is for that reason it has fairly good corrosion resistance.
What's all this crap got to do with it sticking together?
Unless you coat the whole joint surface with superglue, the joint will most probably be very weak and won't last that long. The oxide layer that the glue is stuck to will just break away from the surface and a new oxide layer will be formed on the surface. Resulting in a very weak bond.
Stew has the right idea, and the one I use most of the time. Using double sided tape over both full surfaces will give a longer lasting and stronger bond. But don't use it if you are going to do any thru drilling, as the joint will most probably fail as you penetrate from one plate to the next.
John
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To answer the orig question...Acetone will dissolve a joint made with CA..
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Acetone? Ok good,i been wondering a few times as well what was needed...ever since i glued my indexfinger and thumb together when i wanted to prove superglue wasn that fast...but it was :bang:
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Thanks Strew, how much heat are we talking about? Is a bucket of hot water or a wafting over with the hot air gun enough?
This will be steel Bogs, useful to know about the ali oxide layer though, of course I knew such was there but I thought it was well stuck on!
This particular job is to tidy up the side frames of my little engine project by giving them a skim on my shaper. The pieces are past the stage where I would want to clamp them in a vice even if they would fit so the idea is to stick them to the shaper base plate augmented with a few clamps. The fixing has to be stable enough that I can move the clamps around as the job progresses without the plate workpiece moving even a whisker which would surely throw Sally Shaper into a hissy fit and cause an unsightly gouge.
Thanks John, acetone is worth remembering, I even have a little labeled 'nail polish remover'! (I spoke to a nice lady at the nail manicure booth in the mall)
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Hi John
Yes heat will release supper glue (can't spell cyanoacrylate)
Can't spell super glue either...... :lol: :lol: :lol:
Sorry couldn't resist..... :)
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I've done a few Ali plates and pieces on my little CNC with superglue hold-downs, but it's always a little sketchy-- without coolant they get hot enough to fly off easily, and once you're done, even acetone is a little tedious at removing the dried glue.
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Hi John
It doesn't take a lot of heat higher than 100 deg C though I usually waft a blow torch over the job, just enough to get a straw colour change should do it.
Have fun
Stew
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I had a piece glued up with soup-er glue. steel backing plate alum part
was milling and it started getting a little warm so used a can of spray air turned up side down to cool the part.
the part poped right off. diferent amouts of expansion
might work if you can not use heat
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If you do use heat be careful to avoid the fumes as they should not be inhaled, as I know from experience :doh:
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I know it is getting away from the original question, but for steel and brass, that are to have some heavy machining done on them, I soft solder the parts together, especially if more than two are being done.
Bogs
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Even simpler.
Coat both parts with PVA wood glue, stick a sheet of good quality cartridge paper inbetween and clamp up.
Leave overnight to set and then go to it.
Soak in boiling water to remove.
John S.
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John Bogs, I actually like soft solder, it is the only form of metal bonding I can manage with a hot air gun, excluding glues of course.
John S, that is a good one to remember. :thumbup:
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Just to pick up on something Stew mentioned earlier on; Shellac is an excellent temporary fixative. It dries quite quickly, has a decent strength hold but immediately loses its bond when heated lightly at about 60 deg C (or put in hot water). It hasn`t the strength of superglue but it is good enough for an intentional semi-permanent fixture.
I have loads of the stuff for both my other hobbies, watch repair and pen repair of which I use it daily to seal new ink sacs to the nipple of fountain pens. If anyone wants to give it a go: http://www.cathedralpens.co.uk/index.php?main_page=product_info&products_id=96 and if your in the US, apparently it is very easy to come by in hardware stores by the litre for only a few dollars! (bearing in mind you only use a few drops, it`ll last you years). I`ve only managed to find it in one hardware store over here in the UK but that .5L is still nearly full.
Sorry, hijacked the thread a little but I would recommend having a bottle in the workshop.