Bearings in clocks

[David Morrow]

Since I requested this clock section, I'll kick things off with one of those hotly debated topics - should I use bearings ?

I won't debate whether or not to use bearings with this post. I have made wooden clocks with no bearings, with brass tubing for bushings, and real  bearings. But, when I do use bearings, I use router bearings that I buy from Lee Valley Tools here in Canada. Normally I use 1/4" OD x 1/8" ID bearings for most arbors. For the wind arbor, I use 1/2" OD x 1/4" ID router bearings.

Brian Law and Woodentimers plans show the bearings as being mounted in the frames and the wheels / pinions being locked to the arbor with a set screw. The arbors then turn in the bearings. That OK when you can get them almost perfectly aligned and thereby avoiding any binding. It's also ok when you have zero frame sag, which also causes binding. What I do is press fit the bearings in the wheel / pinion assembly which I glue together, and and let them spin on the arbor rather than locking the gears to the arbor which turns on the bearings in the frame. I find that I have no alignment issues and, frame sag, if it occurs, becomes a non-issue.

The downside is that I have to make brass tubing spacers to keep the gears properly aligned.

I hope my description makes sense.

[John T]

Hi,
I have made a total of 34 clocks and none of my clocks uses bearings although I have used brass bushings from time to time.  In actual fact I've found that the problems a alignment are not worth the effort of using bearings or bushings unless the wheel is turning on steel, that is not to say that if properly aligned bearing wouldn't be effective, I just find them not worth it. 

My longest running clock was put into beat in December 2005, and runs without problems other than keeping it wound.  This clock uses wooden plates, wooden gears and wooden (dowel) arbors.  It is a 30 hour movement running on 3 pounds.

John

[ArtF]

John:

Impressive. Thats a good run from pure wood IMO.

I use bearings where I can, Im not opposed to them anyway. With acrylic I find
sinking a bearing in the acrylic gear helps center it. Lasers dont cut very straight
holes, but a 15mm hole that you press a flanged bearing into makes it run very true.

  Depends on the project and medium Id suppose..

Art

[doc_here_]

Hi folks, please understand that I am in no way an expert but recently reading through some very obscure documents I discovered that the discovery that turned clock making around way back when they were trying to make reliable and accurate ship board clocks to work out longitude was the use of Lingum vitae. This wood was able to self lubricate the bearings, is unaffected by water, salt or fresh, and its use marked a new era in clocks. I read that one of the clocks built back then has been refurbished and is still keeping good time 300 years later. I did a search and found that one of your power companies over there turned to Lingum vitae bearings a few years ago and it has been remarkable in removing all maintenance required and saved them thousands. Another search and a knife making supply company here in Aus. sent me a small block of Lingum vitae which I intend to use in small sections by inserting small blocks where my brass rods will go and hopefully will be able to get around using bearings that way. Unfortunately I then found with further searching that this wood is on the restricted list and is very hard to buy so I seem lucky to have gotten the piece that I did. Hope that this small thought is of interest, thanks for your time, Phil

[David Morrow]

I don't think I have heard of anyone in recent years getting any lignum vitae so yes, you are very lucky. Best to use it very sparingly. It would be a nice tribute to your find to use it for clock bearings.

Another thought that comes to mind when you say it is self lubricating is to use graphite plugged bronze bushings.
http://www.nationalbronze.com/News/self-lubricating-graphite-plugged-bronze-sleeve-bushings-now-available-online/

[ArtF]

Funny, they sell Lignum Vitae , I have a chunk on my workbench. The Navy used
to use it for the drive shaft bearings up here. It really is well known as bearing
wood and lasts a long time.. strangely, Ive never used it, I tend to steel bearings.

Art

[Mooselake]

The local (that's 100 miles east of here) exotic hardwoods place had some the last time I was in there.  Bought a 1 inch square by 12 inch piece, $5 from their web site.  No real intended purpose, but thought it might be handy to try making some bushings out of it.

Wife picked out a 2" square by 36" chunk of purpleheart.  She's not a woodworker so it might be a clue stick...

Kirk

[ArtF]

Theres a few types of it I notice, the real good stuff is sold by the pound, not by board foot.

Art

[David Morrow]

Funny, they sell Lignum Vitae , I have a chunk on my workbench. The Navy used
to use it for the drive shaft bearings up here. It really is well known as bearing
wood and lasts a long time.. strangely, Ive never used it, I tend to steel bearings.

Art

The only time I ever heard of it being used for a bearing was John Harrison when he was in the race to build the clock trying to win the British Admiralty prize in order to more accurately calculate longitude. I suspect anyone using it today is making an effort for something as traditional as possible. Here's an episode of PBS's Nova about Harrison and his clocks. Really interesting.

https://www.youtube.com/watch?v=NENPdT4LASw

[doc_here_]

Yes, that is who and what I was referring to. An amazing tale and a shame that he died before he could collect the prize money.
There is also a great article on their modern use as bearings to be found here : http://www.hydroworld.com/articles/hr/p ... urbin.html
Ps the piece that I got here down under was 1 ?" x 1 ?" x 6" and cost me $30 and $25 shipping, sucks being here sometimes lol