10/5/11

We Haven't Talked About Those Evil Bushings for a While

Email dialog between Clockbuilder Gene (black print) and Clayton (red print):

Clock builder Gene writes:
"I will admit, I have about come to the end of my rope.  At one point I have had my clocks (2) run for up to 48 hours, non-stop. At that point they were running fast, so I thought I would lengthen the shafts by two inches. So, I cut 2 inches off of the 36.25” and added 4” to the middle of the shaft using a lighter colored wood for contrast. When I tried to restart the clocks neither would run for more than an hour. I have tried every think I can think of to get them to run smoothly again. I’ve polished everything that I can get to hold still.  I have even tried to add brass tubing to the ends of the arbors to act as a bearing. If I turn the wheels by hand they seem smooth as silk. But when I add the escapement and weights and try to start them they will stall after a while. It seems like there is not enough force to turn the escape wheel to the next spook. I tried adding more weight to the Weights. With little or no change.  I tried adding heavier string and more of it to fill the take up spool. Nope…………. No good….. no help.
Question: Do you think that it may have been a mistake to put the brass tubing on the ends of the arbors?
Thank in advance for the help………………………. If you have any extra straw laying around may I borrow some…………….. because I have been grabbing at all the straw that is around here.
Wish I had a video camera.
Gene"

"Aloha Gene,

The answer to your question is:  OMG YES! Any sag of the frame whatsoever will bind the arbors with brass inserts. I think you may have found your problem.

In my very first clocks I put brass bushings - big mistake. Now I NEVER put in brass except possibly at the weight end (but don't even consider using them there either).
When I went to the NAWCC Museum and Library in Columbia PA I saw a 300 year old clock still in running condition that used only metal arbors on wood plates. After 300 years you might want to consider bushing, but I doubt it.

Clayton"

"Thanks Clayton. I thought that the brass bushing with oil would solve some of my problems. But after studying the workings for the last week, the bushing were the only thing I could think off that I might change. Guess I’ll go back, fill the holes and re-drill them. What do you thing would be best to use, water base or oil base filler?


The clocks look nice but if they won’t run for more than 10 minutes, I will never be happy with them. My oldest daughter, Stephanie, tried to make me feel better by saying she didn’t care if it runs or not she just thinks it will look nice to have on her wall. She knows I’m a stickler for detail. And before I will let them leave my shop, they will be right."


"To correct my beginner's error in my first clocks, I went back and pounded in wood dowels with wood glue, and re-drilled. Tricky, but it can be done, and I think you'll be a lot happier with their performance. Drill slowly, in and out, with a Brad point bit because this time you'll be drilling with the grain instead of across it...unless you make plugs! 

"You may be right about the plugs. They would be good and tight and not need much glue. I could make 3/8”plugs using a plug cutter from the same wood as the frame and I think the arbors would be happier in the cross grain. And plug from both sides, where needed. If this works I’ll let you. My wife will tell you that I threatened to burn down my shop with the clocks in it. But now maybe I can wait a week or two."

And later Gene writes:



"Many thanks for your help. You were right about the brass bushings. I plugged the holes with 3/8” walnut plugs and re-drilled then to 9/64” & 13/64”.


I think part of the problem was caused because when I cut these holes on my CNC I was having some feed rate problems with it and the holes were not perfect in size. This time I drilled them using a brad point bit that I had ordered from the internet. I only have to make 6 small shaft caps and I’ll be sending these to their new homes. The shop will seem like something is missing when they go. But off to a new project, Riding my Honda Gold Wing to Montana and Glacier National Park in June.


P.S. I think I have solved the problems with my CNC, the last time I used it ran perfectly.


Thanks again for the plans & the help.


I’ll be BACK


Gene"

1 comment:

  1. Glad you've returned to blogging. I can't make a clock right now despite my newly purchased plans, and enjoy your blog.
    Russ

    ReplyDelete

I love comments, but in order for me to have more time playing in my sawdust, I cannot respond to them here. If you have a technical question, please do not post it here, or I will have my wife answer it for me and her technical knowledge is highly suspect. For technical questions, check out the FAQ section of my website, or find my email link there. Mahalo and Aloha, Clayton