Extruder half bearings and alien technology?

The wiki says: "You may be tempted to make just one whole bearing and then to cut it in half. Be warned: unless you own a hacksaw with a 10 micron thick blade supplied by alien technology you will not be able to make this work..."

If you can use a stack of washers cut in half with bolt cutters why does it matter if you cut a bearing in half and lose a saw cut width? It is only half a bearing with no mating half so why does it matter if it is slightly less than half?

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[www.hydraraptor.blogspot.com]

i think it was a (pretty good) attempt at humor. if you can cut a bearing in half and make it work... go for it!

I think the idea is that with a bearing with only a 3mm hole in the middle, a hacksaw can easily wipe out 1mm of that, and that wouldn't leave you with a whole lot of lateral support in the bearing, so you can't readily make two bearings out of one fully round bearing. When ya cut a washer with bolt cutters, you end up with two almost-halves, and a lot more lateral support.

OK I will stick to human technology and make two, thanks.

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[www.hydraraptor.blogspot.com]

I don't quite understand what all the drama is about making bushings. I just drilled a hole of the proper diameter (quarter inch in my case) through a piece of quarter inch bar stock and then hacksawed off the bit I needed and touched it up with an abrasive wheel to get rid of the burrs. Took me about five minutes.

Forrest,
I don't understand, how can you drill 1/4" hole in 1/4" bar? Typo ?

I seem to remember you had a closed hole rather than a half bearing. How does the filament get past the bearing?

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[www.hydraraptor.blogspot.com]

The bar was 1/4 inch thick. It was 3/4 inch wide and couple of feet long.

I basically drilled a hole in the bar, sawed off at a length which fit the slot for the bushing in the polymer pump (I widened the hole to handle the thicker piece of steel, mind) and then sawed that piece in half so that the threaded rod seated in the cradle of steel made up of the half-hole.

The top bushing had a closed hole, but that bushing was above where the filament fed into the pump.

nophead Wrote:
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> Forrest,
> I don't understand, how can you drill 1/4" hole
> in 1/4" bar? Typo ?
>


It's obvious, isn't it? He uses alien technology! That's why the bearings don't cause him any drama.

I guess that I must be an alien then. Funny, I thought aliens were those funny little brown guys who hang around parking lots hoping somebody will take them home and pay them to do gardening work.

Ouch! they also do other work and are they still called aliens now that the Gov. wants them here...

Hello All Bruce W.

As grand a governor as he's been when compared with his predecessor, I'm afraid that Arnie doesn't make immigration policy.

It shouldn't be too much drama for me to make some half round bearings as I do have a lathe and having spent time writing code to mill the half round indentions in the extruder it would be a shame to fill then with something square.

However, my lathe skills are not the best, basically I am relying on childhood memories of watching my dad so it could all go pear shaped. I which case I may fall back on Forest's technique.

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[www.hydraraptor.blogspot.com]

Well I managed to make the bearings quite easily with human technology although I did make it harder work for myself by using steel rather than brass. This picture illustrates why you can't just make one and cut it in two :-



The wiki instructions say to make the drive screw before the bearings but I think it is better to make the bearings first. That way you can try the bearings against the lands while the screw is still in the lathe and turn it down to just the right size. Especially as the wiki has the lands at 3mm and the bearings holes at 3mm, surely there should be a small clearance?

Edited 1 time(s). Last edit at 07/22/2007 06:36PM by nophead.

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[www.hydraraptor.blogspot.com]