Here is a list of all the postings Alan Crawley has made in our forums. Click on a thread name to jump to the thread.
|Thread: Griptru wil not ad just|
The only slight thing that is wrong with your last post Lee is the word "disputed". The bolts are nipped up and left alone, indisputable.
And the other poster's idea of bending the bolts to effect adjustment is horrifying. One part slides across the face of the other.
As you say, the ultimate tightening of the three conical screws holds it all in place.
Lee has summed it up neatly.
I have watched a couple of videos about these chucks and have to wonder if the users have read the maker's instructions. It only claims to repeat accurately at the diameter set, and also that the chuck key should be used in the same hole every time. You have to forget the habit of checking all three. And the same number should be used to unloosen it.
I have used one professionally for a good number of years without problems. The retaining screws are never touched. And I believe I may have stated earlier, if ham-fisted users strain them so they are bell-mouthed the jaws can be corrected carefully on a surface grinder. No need to grind the bore and make the jaw face concave.
My UK made Hardinge has one and the screws under the backplate so there is no way of adjusting on the run so to speak. If the instructions are followed and all taper screws are tight, as long as the mounting screws are tight enough to prevent endplay everything should be ok. No eccentric movement possible.
Edited By Alan Crawley on 19/10/2020 14:15:21
|Thread: Carbon fibre pendulum rod|
All of the above explains how my friend who completed a trip back home from Oz on Concorde from Bahrain arrived here before he left there.
Someone mentioned Fisshguard and I frequently stay with friends there and the shift in daylight is very noticeable.
A further aside-I think the carbon fibre rod looks nice with the brass bob and weights etc.
I fitted the carbon fibre rod as advised and all is well!
I recently used the term "amazingly accurate" when running on a length of 6mm EN3B. This was meant to be a relative term as it is amazing to me, my first ever clock in my ninth decade. It cost well over £300 for materials, and is not as accurate as a £4 clock from Aldi!
Another question, I learned that the term "Regulator" was used as it was the accurate clock in the clockmaker/repairers workshop to adjust other projects. What did they set the Regulator to? Or did it set standard time for the area it was in? I recall reading that railways had problems where different companies ran to different time. Much like today, it seems!
Many thanks for the help and guidance.
Edit:- comma after "to be honest"
I’m beginning to realise my IQ is too low for this conversation!!
i have now made up a carbon fibre pendulum rod with glued and pinned threaded ends.
The original design with Invar rod has a brass tube inside the bob as a compensating device. I guess that this is no longer needed with carbon fibre, has anyone any information or thoughts on this, please?
The clock is still running with an ordinary mild steel rod and it is obvious with the current temperatures how much it affects the time. It is almost spot-on at 6-30 am but probably about 10-15 seconds behind in the early evening, and then is accurate next morning.
This has produced some interesting replies and I particularly liked Duncan's link about gearing. That's life-we all enjoy the situation of "tell us what we want to hear" I wish I had read it earlier and I would not have worried so much about many hours of work being in vain.
Lockdown has at least given me the time to spend on this project and after over sixty years in engineering/toolmaking, and nearly fifty with my own small specialist business, I can still get immense enjoyment from something new and different.
You won't be able to imagine my excitement after a few little setbacks, how excited I was when this clock settled down and ran on its initial test.
I have one other small query about the CF rod, will it be ok where it is subjected to the friction of the crutch? This consists of two 3mm silver steel pins in a brass disc that can be rotated to adjust clearance to the pendulum rod. I would like to thank everyone who has taken the trouble to help me with my project.
Regarding the distance the weights descend and the height of the case, i have managed to calculate that it does not need sixteen turns on the barrels but about fourteen for a month going, and that there is probably just enough room if the weights are wound up to their limit.
I am completely out of my depth now with the information about pendulums that I don't understand regarding the comment I quoted about bob weight being unimportant. I read this in a couple of publications from respected clock makers, and during my process of crude lash-ups to see if my creation would run (an 'expert' told me it had no chance of running because I used involute tooth form) I used various objects on the pendulum rod ranging between around 2 kilo to the correct 4kilo as designed weight for no difference in timekeeping over periods of 36-48 hours. With the correct weight it has run several days spot on.
It's solid wood, so weight don't fall below case.
Edit- case is 51-1/2" inside
As a newcomer to clock making I read lots of information about it, and one thing i learned is that the weight of the pendulum is not important. With my current testing stage, I removed the bob and the clock started and ran without it, albeit quite fast! That surprised me!
The Model Engineer articles describe a glazed case for this clock, and I am somewhat confused about this aspect, too. It's all in Imperial dimensions, so I will use them. It is a thirty-day clock. The winding barrels have an effective diameter of 1-1/4" and sixteen turns, so 1.25 x pi x 16 =approx 63" The cable is doubled with pulley, so effective length is approx 31-1/2". When fully wound up the top of the clock to bottom of the weight is approx. 25", which gives an overall dimension of some 56-1/2" when weight is fully down, but the case is only 50-1/2" inside.Have I missed something?
Steel is 11.7, Invar 1.5. Carbon fibre can be as low as 0
Thanks again Mike, you have confirmed that what I was hoping to do is achievable
With this design the top is easy as he rod goes into 1/2" square brass that clamps the suspension shim.It also means that a metre of carbon fibre is just right.
I can't remember what the difficult to machine material was that we had at work, but we found that a carbide inset just touched on a diamond wheel to bring it to a sharp corner worked well. I imagine it would help on carbon fibre.
Thanks, Mike, that was what I was wondering. I'm assuming you part threaded the steel rod and bored the plain bit, or did you use M6 studding? That would only leave about .5mm wall.
Thanks for the quick replies. They are all interesting, and I had wondered about tube. The only readily availableone I found is 6mm O/D with 1mm wall, and I have no experience of carbon fibre apart from fishing rods and wonder if it would flex too much.I like the idea of tube as it would be the easiest option to make.
I have made the 30 day regulator clock from the book by Peter Heimann and have it running with a pendulum rod of 1/4" diameter EN3B mild steel, due to the cost of the Invar rod as described.
At the end of the book the author touches briefly on using carbon fibre rod.
He points out that it is impossible to thread so threaded ends are glued and pinned in place. The top end is easy to do, but I am wondering how to join the threaded section at the bottom and keep it all 1/4" / 6mm diameter. Has anyone turned this material, as I envisage boring a 4mm hole in the metal and turning the carbon fibre to fit and epoxy and a pin to secure it? I am lucky enough to have a very well equipped workshop, but no grinding machines..
Any suggestions welcomed.
|Thread: Griptru wil not ad just|
I have read numerous times about the tightness of the screws in the backplate. These are nothing to do with the adjustment and they must be full tightened.
In simple terms the chuck is in two parts, the back 'slice' is fixed to the normal backplate and the front part is adjusted on the back part. The screws that connect the two parts of the chuck proper are not even accessible without taking the backplate off.
I have read of someone who advises loosening/retightening the screws in the backplate every setting.
I hope this is clear
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