adjusting the sextus?
  • My sextus clock is just finished, and it seems to run fine, but overnight it lost 2 1/2 hours. Is there a way to adjust this?
    How are the others out there working as far as accuracy?
  • There are several factors that will influence the accuracy of your Sextus, but I think you will find them pretty well covered in the instructions on page 47-48, have you gone through the mentioned stages, sorry to be so vague but it would seem that you maybe have not had the time to get the weight right?

  • When I was initially setting up my Sextus, I checked the natural period of the pendula with no weight and no escape wheel. With this setup, I found that with the adjustment weights in all positions, I could not get the period down to the required 2 seconds. I figured that there would be no chance of adjusting the Sextus to keep time. So I moved the adjustment weights to mid-range, and added small weights to the back of the lower pendulum bobs until the natural period came to exactly 2 seconds. In my case I think I added about 4 grams (blu-tack) to each bob.

    Then with the clock fully assembled, and using 3 kg of weight, It was a fairly simple matter to adjust the clock to keep time using the brass adjustment weights . It has now run for 3 months without further adjustment. Normally it keeps time to within +/- 2 minutes per day, but during wet weather, it can lose as much as 6 minutes per day. I don't know if this is good or bad, but I'm happy with it.

    BTW, IPADs and other tablets have free stopwatch apps which are very useful for regulating clocks!

    Hope this helps.
  • On reflection, I think the accuracy of my Sextus is better than I stated above. I wind it every morning, and it is usually within a minute of the correct time. We have had 2 very wet periods this year, and during these it did slow down noticeably.
  • David...I have to apologize.....It was so exciting to get this first clock running that I completely forgot about reading through pages 47-48. After this, and a couple of days of minor sanding and adjustments.....this sextus is running within a few minutes accuracy per day. I'm sure with a few weeks...(as stated in those pages)....of a bit more minor tinkering, it will be as close as Pauls. Thanks for you input, and Pauls too.
  • @Mike
    All is well that ends well, the main thing is you have your Sextus up and running!

    The setting up of a wooden clock like the Sextus can take just as long as the build and can also be more frustrating, although a wooden clock might seem like a simple machine, it can take a while to grasp all the parts that have to work together in order to have a running clock.

    @ Paul
    Its an interesting point you make when you mention that you wind your clock every morning, back in the day when there were only mechanical clocks they were wound at a specific interval and a specific amount, as are tower clocks nowadays, as experience showed that regularity in winding increased the accuracy.

    That is what the Sextus looks while loosing a minute - every 15 minutes.
    I too will take pages 47 & 48 to bed with me tonight so tomorrow will be a new beginning!
  • Since adding some + - 3" thin slices of sheet lead to the pendula last night, this am. the clock is found to be fast by 12 minutes in eight hours!(yeah!)
    Improvement from the 1 min. every 15 minutes.

    So now I will start shortening the sheet lead strips to fine tune that accuracy.
    But, BUt BUT, first and foremost, I hung a 3 lb. additional weight to the 6 lbs. to help assist the pendula with that additional weight. Three lbs. is way over kill. Since this clock should run with + - 6.5 lb. I will reduce that weight first by half and see if she is still running when I get home from work.
    Then I will start shortening the strips.

    This morning I don't think having the lead strips hanging below the pendula was such insightful placement, so I will change the orientation to horizontal rather than vertical; thinking I have lengthened the pendual and added weight. Since I don't want the lead to show when the correct weight (length) has been determined, best I change that orientation now I believe.

    So two changes this am. reduce weight and change existing additional strip weights on pendula in hopes she is still running potentially fast.

    Please do offer any comments / suggestions as this is my first clock project and my last intention is to come off sounding as if I'm schooling any reader! ; )
    2-9-16 am.jpg
    918 x 1632 - 493K
  • The fact that your Sextus is running is 99.9% of the build, the rest is just tweaking.

    I would strongly recommend getting your drive weight reduced before you start trimming the Pendula, 4 Kgs is too much, I recommend 2.7 Kgs but mine runs comfortably on 2.5 Kgs
    and a customer told me he reduced his weight down to 2.2 Kgs.

    As mentioned in the instructions the amount of drive weight dramatically affects the speed of the clock, so if you now trim/tweak your pendula you will have to start over when you reduce the weight.

    The increase in weight is indicative of a further problem, which should be corrected ASAP (probably friction)
  • Thank you for the comments Dave. I am working on the drive weight reduction now but fear your FRICTION call may be far too intuitive and relevant for my hopes! LOL !
  • Started assembly Friday night, complete and running Sunday night. So far no issues! (Less a lazy left pallet, easy fix)
  • I'm currently running with 2.8Kg and tweaking a fast run time. I've moved the weights down on the pindula and am now gradually working them back up.

    @Chris. I did add a smidgen of weight to that lazy pallet. The search for an appropriate sculpture subject has about burned me out. I may just settle for a solid 6Kg weight (with a pulley) and paint same color as the wall. Hey, post us a picture or a YouTube link of your Sextus in motion!??
  • Will do when Time allows. Nothing special about her, honestly. I keep them simple to move on through projects, as the next one always seems more interesting than the current one. Guess that's what makes this a "hobby " lol.
  • @ marc- per your request, here is a link to the clock-

    She runs on 6 lbs, 4 oz, and keeps time very well in early trials.
  • Cheers Chris! Looks great and nicely done!
    I'm at 6lb 3 ozs. but I have a quarter placed on the backside of the bottom pendula.

    I just can't have this huge 12.5 lb weight hanging below the clock. This is a bit out there but I guess you have to consider the source! LOL!

    Almost about to pull the trigger on this 15" arm span @ 14lb. guy, but still a bit hesitant. Would have preferred a squirrel, but maybe one day it'll show up.
    800 x 1200 - 69K
    1600 x 1066 - 66K
    1600 x 1066 - 63K
  • Nice! After further review of my "lazy pallet ", I discovered I was running too little drive weight (less than stated above ) causing the perception it was "lazy". In actuality, the undersized weight created timing issues for the pallet, which now functions without assistance. In the last 24 hours, she has only lost 40 minutes, but environmental factors could be at play, since she has moved from a cold damper workshop to a dry warm living room. I plan on letting her find her natural beat over the next 2 weeks before drawing any conclusions and making adjustments. Just my past experience telling me to be patient :) BTW- What did you find/do that helped you with the reduction in drive weight? Friction in the arbors? Just curious. ..
  • I believe adding the quarters to backside of each bottom pendulum has allowed the clock to run with less drive weight. Maybe my deduction is wrong, but that was the last change done prior to the resulting progression of removal of excess drive weights.

    Still running with only 99 oz. Still fidgeting with fast times. Time I let it run 24 hours and get a one day result. Benn difficult not to readjust after only a couple hours!
  • Yeah, tough to resist the temptation! I know a solution for the need to fidget...

    Build another clock lol. If you do, you will be so busy building, staring, tweaking the first, adjusting the second, staring at the first, tweaking the first, thinking about the second underway, working on the second, thinking about the planned tweeks for the first, wanting the second to run you wont have time to tweek the first every hour lol.

    Just my solution.....your thoughts may vary......:)
  • Well Dave has that "tonic" you speak of but he says it's not in kit form yet! Humm, leave me wanting too long and I may stray...
  • Duodecimus the one I'm referring to.
  • Ok...what may be a final update. Temperature and humidity levels have stabilized to get some results, along with some run time. After tightening the frame from sag ( expected as most new builds need this) and no further adjustment she holds around 2 minutes a day (generally slow) which is absolutely respectable and acceptable. No stoppages in her first week. Guess I can officially say. ....


    Fun build, and on to the next.
  • Great news Chris - Congrats. I enjoyed the banter!
  • As did I! Although the next build isn't of a woodentimes design, I plan on stopping by regularly, so no need for the banter to end my friend; )
  • My Sextus is now 5 min. fast in 8 hrs. so still tweaking the pendula weights up the all-thread.

    I also just received the sculpture weight that will demand the need for a pulley set up. This should be a fun set up to construct!
  • Ever think of potentially reducing the drive weight to correct the speed?
  • My perception is I'm not a hard head really though reality really appears to be so. Dave has spelled out reducing the weight back on on Feb 9. My stubborn ignorance has kept me trying to work azz-backwards using a set drive weight. (similar to the sculpture's)

    I pick up the scroll saw today so I'm thinking of shelving the sculpture idea and just get this baby running in the "classic" style.