Here is a list of all the postings Alan Charleston has made in our forums. Click on a thread name to jump to the thread.
|Thread: Boxford Cross Slide & Top Slide Disassembley|
I've bought a sad old Boxford AUD lathe which I'm in the process of resurrecting. I've got the headstock and gearbox working OK and now I'm working on the carriage. I've struck a couple of problems.
The first is that I can't get the top slide off the cross slide. I've taken the bolts which clamp the rotating mechanism out and can see the ends of the clamping pins at the bottom of the holes but I can't get them out far enough for the cone on the bottom of the top slide to come out of cross slide. I seem to remember Tubal Cain on Youtube had a similar problem with a South Bend but I can't for the life of me find the video.
The second problem is in disassembling the top slide. I've taken the screw and the gib out, but the brass nut stops the top part from sliding off the bottom part and the bottom dovetail is to wide to allow it to come off sideways. It seems to be an impossible puzzle.
Any suggestions to get round these problems?
|Thread: John Wilding 8 day Weight Driven Wall Clock|
When I started this clock 10 - 15 years ago I was having trouble figuring out how the bits out the front worked as well so I drew up how I thought they should go and sent it off to John Wilding. He sent my drawing back with a penciled addition showing where the spring went (see photo). He didn't make any other comments so I assume my drawing is accurate.
I hope this is helpful. I'm not up to this part yet and I won't be until I can get the clock to run properly. I'm pretty discouraged at the moment and haven't done worked on it for the last 6 weeks or so.
I agree that an eccentric at both ends of the pallets would be a good idea. As it is, the amount of adjustment is pretty small before the pivots start to bind.
Thanks Stephen. I "polished" the ends of the pivots before and after I hardened them using 1000 grit wet and dry paper. When I've got it apart I'll give them a polish using a felt pad on the Dremel and Brasso.
Thanks for your comments. I didn't make the pendulum bob as laid out in the book which is a quite streamlined design. Instead I used a piece of 40mm dia. steel 100mm long which has the same weight as I calculated the lead filled bob described in the book to have. The air resistance of this is going to be more than the bob described in the book which is only 25mm at its thickest point and 90mm in diameter. Although at this stage that's not what my problem is (there is barely enough ummph to keep the crutch alone oscillating) I'll bear it in mind if I make some progress in increasing the force from the escape wheel.
Yes, I initially ran it without oil as everything seemed to be rotating freely and I could drive the train by blowing on the escape wheel. Without oil I could only get a few beats out of the crutch but after I lubricated the pivots it more or less ran continuously.
You say I could try a heavier oil for the winding drum pivots. I have some clock spring oil. Would this be a better bet?
From what you say about lubricating the pallet faces, (which I didn't do) I presume one of the jobs to be done when I get it apart is to polish the contact surfaces of the escape wheel which still have the machined surface.
All of the small pivot holes are reasonably loose but the large diameter winding wheel pivots are a reasonably close fit. I'm not sure of the best way to ease these out as one end is an odd size which I needed to make a special reamer for.
The other area I'm not sure about is the adjustable front pallet bush. If this is rotated much, it binds onto the escape wheel pivot because the holes in the front pallet bush and the back cock aren't in line. This is made worse because of the thickness of the front bush. I've tried to get around this by drilling the hole out except for the back 1/8" but the amount of adjustment achievable before the pivots start to bind still isn't much.
As far as the lantern versus cut pinions go, one of the problems with lantern pinions is that you can't look at them end on to see how they engage with the wheels when you are depthing them. If I have the depthing wrong, I'm not inclined to plug the holes in the frame and start again. At some stage enough will be enough and I'll move on to a more rewarding project.
Thanks for the comments,
I've got exactly the same problem. Without the pendulum in place the crutch goes backwards and forwards but there is not enough "ummph" to maintain the pendulum after it is set going.
I was hoping that I had got to the stage where either it would work OK and I could proceed with the bits on the front of the clock or it wouldn't work at all which would give me an excuse to give up on this project from hell. Sadly it's half working so I suppose I'll keep on going to see if I can get it going properly.
I'm going to disassemble it and open up the pivot holes, polish the wheel bearing surfaces and the pinions. I've gone for the lantern pinions which may have been a mistake but I'm not going to machine solid ones.
One thing I found made a difference was to put a bit of clock oil into the pivot holes - this sped up the crutch oscillations a lot.
If all else fails, I'll try your idea of hanging the weight directly from the main wheel spool which will double the force to the train - I don't mind winding it every 4 days rather than every 8.
I wonder what the ratio of finished clocks to books sold is.
I repeated the test I did using a reamed brass collet onto a 3/32" silver steel shaft with both the surfaces of the shaft and the collet roughened with 240# wet and dry emery paper. The emery paper was rubbed along the axes. It made a big difference to the strength of the joint.
I did the same to the arbor through the barrel and after waiting 24 hours I hung the weight off it. No problems. If it's still OK tomorrow, I'll continue with the rest of the train.
Thanks for the help.
Thanks for all your comments. Both the silver steel arbor and the reamed hole in the brass were shiny which could have been part of the problem as well as not leaving it to cure for long enough. As per the comments, I'll try roughening the surface of the silver steel with 240# wet and dry emery and try getting a bit of scotchbright through the hole in the brass.
The first joint I'll make will be the arbor going through the barrel which holds the weight string. I'll test the integrity of the joint by hanging the weight 1/2" off the ground and without connecting the rest of the train. I'll leave it for a couple of days. Even if it fails, I don't see it causing any damage.
Thanks for the help,
I had trouble finding anyone who stocked Loctite 638 locally so I got Bondloc B638 which I was assured was the equivalent, and as it was made in England (i.e. not China) I bought a bottle.
I've done a test by gluing a piece of 3/8" brass rod reamed out to 3/32" onto a piece of 3/32" silver steel. I degreased both parts using isopropyl alcohol.
The bottle said it took 1 hour to fully cure so after 2 hours I tried twisting the brass off the shaft. It wasn't all that difficult and I got a bit worried as to whether the joint was strong enough so I downloaded the Technical Data Sheet from Bondloc. It gives the full cure time as 24 hours. It also says that the surface keying action is greatly increased by a rough surface finish giving higher shear strength. They recommend a roughness of 30 - 100 micons whatever that means.
Does anyone else roughen the surfaces, and if so, what is a good grade of emery paper to use?
I've redone the trial and given the silver steel a bit of a rub with 600# emery paper and I'll give it 24 hours before I try twisting it off again.
Good to hear from a fellow chemist. In the past I had a tube of Loctite in the fridge for over 10 years and it seemed to last OK. I figure that if the recommended storage temperature range is 8 - 21C, it's better being in the fridge at say 4 - 5C than at ambient which can be from say 5 - 30C here. The relatively stable fridge temperature will reduce the propensity for the bottle to breathe as well.
Thanks for all the comments. I'll follow the advice and Loctite the wheels in place. It's interesting the general opinion favours using Loctite 638. Wilding recommends 601 in the book - but that is more than 25 years old now, so I'll go for the 638.
I'm worried about using Loctite as I've had problems in the past when I've mucked about too long getting the position right and having a piece freeze in the wrong position. I think I'll make a 1/2" OD/ 3/32" ID collet bored out to say 1/4" 6mm from one end and use this to position the wheel on the shaft before adding the Loctite. I can then apply the glue to the shaft and slide the wheel into position up against the collet with no delays. The bored out end will stop the wheel sticking to the collet.
|Thread: Machinery's Handbook|
I've got my Grandfathers 1914 Fifth Edition which I still use. Tapers, threadforms, involute gear cutters etc. don't seem to have changed - I hope.
|Thread: John Wilding 8 day Weight Driven Wall Clock|
Thanks for that. Just to clarify, does the Q factor of 10,000 applies to the pendulum alone - without the crutch?
Also, pardon my ignorance, but is the amplitude the horizontal distance the pendulum travels or is it the angle it moves through?
Another couple of extra questions,
I have had the pendulum oscillating with the crutch and pallets operating the freewheeling escape wheel. The pallets made the escape wheel rotate backwards. Does this mean I've got the pallets about right?
I haven't attached the wheels to their shafts yet. John Wilding recommends Loctiting them in place but I think I would prefer to slit the arbors and fit collets to compress them onto the shafts as he recommends for attaching the crutch to its' shaft. I can then adjust them to where I want them to sit easily. Is there any reason why I shouldn't do this?
Thanks Stephen - Just what I wanted to know.
After waiting for weeks my 0.2mm slitting saw finally turned up so I have been able to cut the slots required to get the pendulum installed. It's amazing how the suspension spring lets the pendulum oscillate for a couple of hours when it's set in motion.
I now need to install the crutch. The book gives the dimension of the slot which goes around the upper block as 3/16" which is the same as the upper block. In my case, this has resulted in a tight fit. Am I right in thinking that it should be a loose fit with the slop taken up by the adjustable shim? If so I'll file the crutch slot out.
Does anyone have any photos of the way the upper block fits into the crutch?
I've made the pallets, so once I've got the crutch sorted out I can look at putting everything together and see if it ticks. Exciting times indeed!
Thanks for the help. One of the problems I struck was that the book says that the line GH shown in drawing 2 should pass through C and between F and D. It doesn't specify how it should pass between F and D. I have therefore drawn GH such that it passes through a point midway between F and D and generated a drawing of the pallets which I have printed and glued to a piece of 1/16" brass. I'll follow Bob Stevensons advice and see how I get on.
I wonder if someone can help me with the pallets for this blasted clock. The method for marking them out using a depthing tool shown in Wilding's book is too complicated for me so I have been trying to simulate his method using a drawing program to generate a paper pattern I can glue onto the carbon steel blank. The problem I have struck is trying to understand the situation shown in drawing 2. As I understand it, the pallets are supposed to cover 71/2 teeth on the escape wheel. As far as I can see from drawing 2, the pallets cover 8 teeth and appear to lock the escape wheel so it can't move. Any help will be gratefully received.
Thanks for the link to Cobb's site. My problem is that I am in New Zealand so getting stuff here could be expensive and slow.
Thanks for the help. I got stuck in and have made the back cock.
The plate connecting the two pieces of angle was silver soldered and the pendulum post was soft soldered into position. I'm pretty sure it will be strong enough.
I haven't slit the post for the pendulum yet as I don't have the .006" spring steel or a 0.2mm slitting saw.
I can source some .006" spring steel shim plate locally. Will this be OK for the suspension spring?
I will order some 0.2mm slitting saws from CTC Tools. At $2-50 each I'll get a few of them I think. The thinnest saw I've used to date is 1/16" so any suggestions about things to watch out for will be welcome.
Here is a picture showing where I am at the moment. The wheels and pinions haven't been loctited to the arbors yet. I want to have the pallets in position so I can see the whole train before I set them in their final positions.
Thanks again for your help.
Thanks for the information. It's just as well I asked for help instead of charging ahead on my own. You are right about me using the old (1990) book. I have made the lantern pinions. I'm the same as you with regard to a mixture of imperial and metric.
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