Using pipe freezing kits for shrink fitting?

[Jelly_Sheffield]

Has anyone had any success using a DIY pipe freezing kit for shrink fitting small shafts?

Ideally I would use LN2 or Dry Ice, but that's logistically complicated by comparison.

I'm assembling a custom bearing race onto a 16mm internal grinding spindle, so I'd rather use cold than heat to minimise potential distortion.

 

[addjunkie]

Put in a polly bag, wait till the Mrs goes out, and put it in the freezer. If it doesn't fit, buy her a big chest freezer

 

[Agroshield]

Do you have an example of the type you are considering? If it is similar to the Arctic Hayes one sold by Screwstation, it may not go cold enough to produce any significant shrink.

The refills are hideously expensive. You could look at the MSDS to see what they are using to produce the cooling.

More professional versions are like a mini-air conditioning plant (have to be gassed up occasionally). That would also give you an idea of the lowest temperature they would reach.

My gut feeling is that pipe freezers would not beat a domestic freezer.

I saw someone on YT with an attachment for a CO2 cylinder (looked just like a bag) that would make lumps of dry ice. I was under the impression that CO2, as cellar gas, was not too difficult to obtain.

 

[Jelly_Sheffield]

Do you have an example of the type you are considering? If it is similar to the Arctic Hayes one sold by Screwstation, it may not go cold enough to produce any significant shrink.

It is the Arctic Hayes type, ostensibly they can get down to -50°C, which is about double what my freezer will do...

But I have my doubts about this in practice.

I saw someone on YT with an attachment for a CO2 cylinder (looked just like a bag) that would make lumps of dry ice. I was under the impression that CO2, as cellar gas, was not too difficult to obtain.

I was under the impression those use liquid draw-off cylinders but it's definitely a thing I could do.

Given it's not something I do very often, it would probably be just as economic to just get organised and pick up a styrofoam tub of dry ice from my local BOC, and I wouldn't end up with yet another cylinder on rental.

 

[Jelly_Sheffield]

Put in a polly bag, wait till the Mrs goes out, and put it in the freezer. If it doesn't fit, buy her a big chest freezer

She's very tolerant, so no subterfuge required, just pop it in the bottom drawer with the bags of un-butchered rabbits.

 

[Agroshield]

...ostensibly they can get down to -50°C...

I think that means that would be a delta of roughly 70 degrees from ambient.

Even dry ice would only give a delta of roughly 90 degrees.

Would you not get a very similar delta by putting the bearing into the kettle (or a 120 degree oven)?

I think this is the bag thing I saw:

https://www.ebay.co.uk/itm/386956936550 (choose thread, but pub gas might not be BSP).

 

[addjunkie]

Always easier to heat than cool!

 

[oldbikedavey]

CO2 fire extinguishers work a treat for chilling....
Stick the component in a closed in expanded polystyrene box, or whatever, then blast the thing.
Check with an infra - red thermometer, and blast again....

 

[hotponyshoes]

Pub gas bottle turned upside down, cable tie a pillow case or something over the outlet.
Will be about -70 in a coolbox

Should be easy enough to find a free fire extinguisher although the co2 ones don't seem to be particularly common..

You can buy it in small amounts but the postage usually costs more than the product so maybe have a look for a local supplier?

 

[indy4x]

Years ago I used to rebuild Triumph GT6 rear hubs, the ones with rotoflex couplings on the shafts.

The inner bearing races were stupidly tight to install, hub went in the freezer, bearing in the oven and they used to just fall onto the hub

 

[timgunn1962]

Can you use a combination of warm and cold?

For fitting bearings to 40-50mm shafts at work, putting the bearing on a radiator for half-an-hour makes a huge difference to ease of installation. At equal temperature, it's usually a 2 kg hammer and steel tube job. With maybe 30-40 degC of temperature difference, the bearing slips on by hand. On site, putting the bearing in a poly bag and dunking it in hot water generally works: it's a rare site that doesn't have some means of making a cuppa.

I've done stuff at home where the female part has gone in the oven on its minimum (the setting I use for making jerky) and the male part has gone in the freezer. With neither part going more than maybe 50 degreesC from room temperature, distortion isn't likely to be a problem. I've usually been more concerned about melting/separating the bearing grease than about distortion.