CNC Clock Build W.I.P.

[J-G]

...so don't be disheartened Mate. "People" (well at least Don & me anyway!) ARE reading - AND enjoying.

Not really 'disheartened' but it would be encouraging to see [Views] changing - which was possible up to 1K but beyond that the forum just reports 2K, 3K etc. and it takes some time to record 1000 views

To some extent it's a matter of knowing that what one does is useful to someone else which is why I record all the mistakes! No matter how forward thinking you may be there always seems to be an opportunity for 'life' to trip you up.

The .PDF views are noted separately from the thread views so I can tell if the .PDF has been downloaded which is why I had concerns over Don's welfare.

 

[paulrbarnard]

Not really 'disheartened' but it would be encouraging to see [Views] changing - which was possible up to 1K but beyond that the forum just reports 2K, 3K etc. and it takes some time to record 1000 views

To some extent it's a matter of knowing that what one does is useful to someone else which is why I record all the mistakes! No matter how forward thinking you may be there always seems to be an opportunity for 'life' to trip you up.

The .PDF views are noted separately from the thread views so I can tell if the .PDF has been downloaded which is why I had concerns over Don's welfare.

I'm certainly enjoying it! Just commenting as I don't want you to stop posting before you have finished.

 

[J-G]

Thanks Paul - that's good to know.

 

[Jester129]

So engrossed in the write-up that I (and I'm guessing umpteen others) fail to make a comment.
Don't be disheartened, I'm sure there are loads of us watching, but just staying silent. I certainly don't have the skill required to do what you're doing.

 

[J-G]

That's great Jester - not that you fail to make comment, but that you are engrossed. It hopefully means that my writing style is 'interesting' Without feedback I often feel self-indulgent instead of potentially passing on knowledge.

I'm sure you could have the skill required, it's just that your interests lie in a different sphere so you haven't needed to acquire some of the skills that I have devoted my time to researching.

 

[donwatson]

Yes, very minor, the biggest one was life getting in the way of everything. I was 81 on the 9th and it coincided with a very good update from you. At my age a birthDAY usually turns into a week (and I am thankfull for it).
As I mentioned before, I had constructed a clock from 6mm plywood and brass rod and all cut on the Stepcraft CNC milling/router machine. I had no success with that and was wondering if I should try again. Your article has inspired me to do just that but when is another matter. In spite of all the frustrations I think I treat all these projects as FUN things and all part of the learning process, YES, even at my age your thirst for knowledge does not diminish. I am off now for elevenses.
take care and stay safe
Don W

 

[J-G]

Good to have that confirmation Don. In these 'weird' times one cannot make assumptions that all is well.​

==============================================================================
19th Dec
Yesterday was taken up mostly with bringing the WIP up-to-date but I also spent some time making a pair of 20T Gears for a Startrite Mercury 2 drill which is being restored and the owner was having problems finding replacements at a sensible price. I did get the drawing of the Rear Frame converted to a .DXF file though.

Due to other pressing issues (Strictly Final ) I only got 3 of the four Rear Frames machined today and even then made an error on the first because I forgot to change the Profile MOP from the default [Outside] to [inside] ! - I let the Denford finish the first recess which made it 14mm Ø instead of 12mm Ø. Since I hadn’t actually cut the Maple inserts it made little difference - I just had to remember to make one of the Maple buttons larger.

20th Dec
The fourth Rear Frame was machined ready for plugging with Maple buttons this morning and I remembered to take photo’s so you can get a better understanding of how I use the Screw Hole Grid on the Denford table to make location jigs along with clamps. Although the Eccentric Clamping Jaw in Fig-161 has fixing holes at 40mm centre (which fits the grid) in this case I needed it to be at 20° so one screw went into a grid hole but for the second I used a woodscrew into the ply sacrificial table.

Because I needed to re-position the frames once the Maple Insert Buttons had been glued in so as to cut the Bearing recesses I did not want to disturb the side locating block but at this time I hadn’t made the Maple Buttons. These buttons are 12, (14) & 18mm Ø and 6mm thick so can come out of offcuts.

In Fig-162 you can see the 12 buttons I need which have been machined using an ‘up-cutting’ end mill. The benefit of ‘up-cutting’ is that it lifts the waste

material out which would otherwise be pushed into the narrow grooves potentially jamming the cutter but as you can see, the downside is that it leaves some tear-out. This is no big deal really as they will be glued into the Frame and sanded off flush before I cut the Bearing Recess. To make it easy to glue them into the Walnut I do need to ‘ease’ this torn-out edge because the recess and the button are cut to the same size. Up to now I’ve done this by hand with a 2nd Cut file, however, I suddenly had a ‘light-bulb’ moment and realized that it would be a simple matter to use an engraving cutter - which has a 20° relief angle (Fig-163) - to simply trim the edge, putting a small chamfer on it which would provide an easy squeeze under the bench press. Taking photo’s inside

the Denford is not the easiest job so I’ve drawn a cross-section below the photo’ to make what I’m talking about as clear as possible.

To also make it very clear how these Maple buttons fit into the frame, in Fig-164 you can see the top two ready to be trimmed down before going back on the Denford to

have the Bearing recesses cut.

Once the Bearing recesses had been cut it only remained for me to prepare a new jig to hold the Frame perpendicular to the table so that I could cut the last two recesses for the Frame Spacers and I completed those late in the evening so tomorrow I hope to be in a position to build the basic frame.

Since I didn’t photograph the Front Frame in position for

machining the top threaded inserts - resorting to a drawing - Fig-165 is a photo’ of the rear frame in the similar orientation to have the Spacer Recesses cut. They are ostensibly in the same relative location since they are at opposite ends of the Frame Clamping screws.

The first attempt at assembling a frame mostly went as expected and I was pleased to see that the holes for the main centre spindle aligned spot on but I then noticed that I’d forgotten to drill & tap the holes for the ‘beat’ adjustment so that will be a challenge to overcome shortly - certainly before I do any glue-up of the spacers or the Frame Brace. The tentative assembly has revealed that the attention to detail as far as using jigs has paid off since I was easily able to slide the front frame down the spacer screws bringing both frames face-to-face. I will however need to do some ‘fine adjustment’ to things like the Frame Brace, Bottom Frame Spacer and Vertical Adjuster block – this is not unexpected since although I’m using CNC for much of the manufacture, some parts have to be done on the Mi

ll or Lathe so are subject to my personal reading of machine dials.

The part assembly does not have a ‘natural’ base which would enable it to stand alone so I had to take it a little further and fit the components which will ultimately fix it to the wall.

There is a Wall Plate with ‘Key-hole’ slots - see Fig-116 in WIP-24 - and I was again thankful to find that the two Mounting Buttons (Fig 117/8) dropped easily into the key-hole plates with no further adjustment so I could quickly screw the Wall Plate to a door and hang the part assembly to take a photo’.

I have to hope that the Dial Mounting Pads will align as easily!

Well that is very fortunate! My concerns over drilling and tapping the beat adjusting holes was unfounded.

It was a simple matter of using a slightly extended holder for a 2.5mm Ø drill in the mill and my standard T-wrench tap holder just cleared the top of the frame while still getting the tap through the one side. The two holes do not need to be absolutely aligned as there will be two separate grub screws acting on each side of a brass plate.

Before I can start a real assembly (glue-up) I will have to spend quite some time in sanding all the components to 320 grit, apply sanding sealer and MC Wax. The frames have been sanded to 120g but the rest are pretty much all straight off the tool.

[EDIT] - I realized that I'd forgotten to attach the .PDF so I've taken the opportunity to add another Photo'

22nd DEC
I didn’t expect to get much done today due to other work that was temporal but I did find the time to do an assembly of the parts that - although not properly finished - are at least pretty much to size. That does not include the Dial because I haven’t yet made the Dial Pads.

I will have to do some fine fettling of some of the Gear teeth to ensure that there are no ‘bindings’ at some parts of each rotation but overall the first mock assembly proves that they are free to run for at least 95% and all the spindles do fit into the bearings when the frames are clamped together with the spacers!

=================================================================================

Although I'm not going anywhere for the 'celebrations' I doubt that I'll get another posting done 'til they are over so I'll just wish everyone a Merry Christmas & a hope for a new year which is better than 2020 has been!

 

[donwatson]

Thanks again JG and a Merry Christmas to you and yours. Have a safe and healthy New Year.
Don W

 

[J-G]

Thanks Don - I've just done a small edit and added the .PDF file which I'd forgotten

 

[AES]

Thanks J-G. Your .pdf downloaded (but NOT read yet)!

If I haven't already said it - I forget, a lot on right now - best wishes of the season to you and yours, and stay healthy. All the best for 2021 (by which time I WILL have read/digested all your o/s .pdf's)!

 

[J-G]

In these strange times of isolation - or at least social distancing - 'holidays' and 'celebrations' don't have the same demands on ones time so working at a hobby does at least fill the day!

24th Dec
Having done all that I could to prepare for the festivities I found time to look at how I was going to make the hands. These are to be only 1mm thick for the majority of their length but the ‘hubs’ need to be 2mm so since they also have to be 200mm long and 20mm wide they present a number of problems. Mostly as regards holding the material.

For some reason beyond my ken, I thought to use the same methodology that I’d been using for the other components even though I knew that I would be using thin sheets of Walnut 60mm wide, 3mm (ish) thick and 430mm long. Actually the 3mm thick was after I’d removed the thicker centre part of the material I’d selected which was a remnant left after cutting other bits from the large Walnut plank. I forgot to take a photo’ so Fig- 169 is a drawing of the cross section which came about because I first ripped the board on the table saw and finished the separation on the bandsaw. (I hate waste )

All went well as far as skimming the surface was concerned and I was selective in the order in which I did the CNC machining, first taking out the main lengths of the hands to 1mm below the hubs, then cutting the axle holes before moving on to the outline which I knew might cause a problem even though I’d built in nearly 50 ‘holding tabs’.

The biggest problem came when I pushed my luck and decided that cutting the outline another ½mm deeper to make sure that it was cut though was wise - it wasn’t !! - At this point I hadn’t done some operations and was disappointed to find (after returning to the workshop - multi-tasking again!) that the blank had disintegrated.

I did recover two of the four - and fortunately one Hour Hand and one Minute Hand so I do have a pair. They needed quite a bit of ‘fettling’ and I had to resort to my Jewellers Piercing saw to cut the ‘spring’ slots but ultimately I did get them fitted to the first assembly in time to show the current state of the Clock to those who are intended as the recipients during a Family Zoom meeting tomorrow.

25th Dec
I hadn’t intended to be in the workshop today but since I had done all the festive food preparation last evening and the fact that I don’t have youngsters demanding attention, there wasn’t a lot to do before actually starting cooking so I found myself reviewing the options, and indeed ‘getting my hands dirty’!

I already had a second ‘sheet’ of Walnut prepared because I needed another two pair of hands but using the same method of holding was obviously not going to produce a better result.

Why I hadn’t previously thought about using double-sided adhesive tape I don’t know but it suddenly made the most sense. I needed to prepare a sub-base using the surfacing fly-cutter and make sure that the Walnut had a clean flat surface which just meant a quick rub on the linisher. In Fig-171 you can see the double-sided tape on the walnut and the prepared sub-base in the background. Fig-172 has the Walnut affixed ready for machining.

I didn’t need to modify any of the G-Code so by just changing the cutter and adjusting the ‘Z’ height, I could cut the second set of hands.

This time I did get the spring slots cut with a 0.8mm Ø burr before cutting the outline, it was only when I came to do the finish outline cut that I had a problem. Since I didn’t use a full coverage of double sided tape - ostensibly because that would make the removal of the finished hands, without damaging them, more difficult (but primarily because I’m a cheapskate and DS Tape is relatively expensive - and can’t be reused!). The end result is that one of the Minute hands had lifted away from the sub-base and the stresses of the final cut - albeit only 0.3mm wide - was greater than the 1mm thick Walnut could stand so it broke away at the junction of the stem and the pentagon counter-weight. (Fig-173)

This means I still need to make two Minute Hands and one Hour

Hand but I still have two smaller thin Walnut off-cuts, though they are only 210mm long which is a little tighter than I would like but holding them with DS Tape will get them done I’m sure.

26th Dec
The two off-cuts needed only a short time on the linisher to get a flat, smooth, surface which could take the DS Tape but I still took all day to finish off the last hands.

The centre holes are machined as an ‘friction interference’ fit of 0.2mm on the spindles and the ‘spring slots’ are intended to allow easy fitting and the means to re-adjust the time by simply moving the hands.

27th Dec
Now I have the hands fitted to the first ‘mock’ assembly, the Dial needs to be attached but as yet I haven’t made the stand-off pads. They have been left until I can be sure just how much the ‘stand-off’ can be. They were designed at 6mm and measuring the clearance between the Frame and the Dial that may be a little too much so I’ll reduce it to 5mm. Unlike ‘normal’ clock hands which are usually made from thin brass sheet which can be bent, Walnut won’t take kindly to that treatment

The Pads are another example of a component that is made much easier by having a CNC

option. They needed to be ‘face-grain’ so a set of simple 20mm Ø circles drawn at the appropriate place in CorelDRAW! produced a .DXF file and ultimately G-Code which cut superb 20mm x 10mm Maple Buttons which were easy to mount on the 4 jaw chuck (Fig-152 - WIP-30) for 2nd & 3rd operations. I’m particularly pleased with the fact that once I’d ‘sized’ the first tenon to fit the recess I could simply ‘dial in’ to the same settings on the lathe and get the same press fit in all the others. In the foreground of Fig-175 there is the 20mm Ø button as it came off the Denford and in the background are the two (marginally) different finished Dial Pads. They are only different because the two Pads at the top line up with the threaded inserts so need to have a clearance recess for them.

28th Dec
Now the Dial Pads are in place it becomes very obvious that I haven’t made the Signature Plate that covers the Bottom Spacer Thread Insert, so today I’ve been working on that. It is customary to mark clocks with a full signature or at least a monogram. In my case I mark all of my work - usually with a simple 5mm Ø copper disk into which I’ve stamped my Silversmith’s Sponsor Mark. Due to the limitations of size (2mm high) my mark is a monogram in a simple pentagon. Fig-176 is an endoscope screen grab of the punch but the original version is a ‘fancy’ monogram

in a Reuleaux Pentagon (Fig-177). After

a number of tests I’ve discovered that unfortunately that can’t be cut into wood - even close grained Maple - and still retain all the detail, smaller than about 2" high so I’ve settled on the compromise of a ‘filled’ version which will finish at 20mm high on a 25mm Pentagon.

 

[Yojevol]

Just a point of ergonomics, JG. The walnut hands may get lost against the similar material behind. I'm having this problem on my clock with maple hands in front of the birch ply components behind. It may be worth trying a sample of maple before committing to further manufacture.
Brian

 

[J-G]

Good call Brian, I had considered that issue some time ago (during the design stage) and thought that 'Gold' leaf may be a solution.

It may still be even adding gold leaf to the tips might be an option.

Due to the 'scrap' hands, I have plenty of 'test bed' pieces.

 

[donwatson]

Thanks again JG

 

[J-G]

I had meant to post this last night but got somewhat distracted

29th Dec
It never ceases to amaze me how long some simple (apparently) little components actually take to make. The Signature plates took all day - well I did have some other bits & pieces to do and had to let paint dry - but essentially with the time taken to set up a location jig and the numerous tests to get the best engraving I didn’t get anything else done. More to the point - they are all scrap!!

I only discovered this when I came to attach one to the mock assembly and was puzzled by the fact that it wasn’t central on the fra

me.


It took me a while to fathom what was wrong and only resolved when I came to photograph two of the plates side by side to demonstrate how they are fixed that I couldn’t align the bos

s correctly.











I thought that I had been meticulous with positioning the various elements (Pentagon, Circle... which are on opposite sides) accurately and also central to the blank which had to be turned over and was surprised when the surface clearing cut was about 1.5mm out. Without much thought, I made an adjustment after flipping the blank so I suspect that that was my main error.

30th Dec
I’ve just measured the position of the surface clearing polyline in the CamBam drawing and find that it is NOT central on the blank There is a difference of about 3mm (I wasn’t looking for micron accuracy!) so that does seem to explain it.

Since I have to start again, along with the correction of the surface clearing line, I’ve made a few small adjustments to the Monogram which I think will improve the final result.

It looks as though there is quite an improvement. There are now three of the four sitting in the Denford waiting for a final surface clean-up when the paint has dried overnight. Fortunately I watched while the 2mm cutter did the pentagon outline so was able to abort the run when it began to slip out of the collet — how could I forget to tighten it and leave it only ‘finger’ tight?? This meant that one of the holding tabs was removed so during the finishing cut, it broke away.

31st Dec

Fig-182 is the back of the ‘One that got away’ (recovered) showing that the mounting boss IS in the correct place and Fig-183 shows the remaining three waiting for the paint to dry before the final skim. I’ve already done a 0.1mm skim but there were depressions in the paint fill so

I’ve applied another coat which will be skimmed again later today.
I think that having the monogram ‘filled’ is better than just a thin film in the depressions.

With just a little experience of the effects of engraving depth and very minor adjustments to the original outline (tenths of a millimetre) it surprises me how much improvement there is to the finished work.

On the left of Fig-184 is the first attempt, which went wrong due to the mis-placed fixing boss, with the deeper cut and surface painted monogram and on the right the second attempt cut only 0.3mm less deep and fully filled with Acrylic Paint.

With the end of the year fast approaching, I’ve reviewed what is still to be done as far as component manufacture is concerned and see that the only parts still to be made are for the ‘Weight’. Though I’m still in two minds as to whether to buy in winding handles, which are standard parts available from the likes of Cousins, the main issue being that I don't have a broaching facility to cut deep square holes.

The Driving Weight has been left ‘til last because until I have a fully assembled clock I can’t be sure how much weight will be needed. I know that it will be made from a clear Acrylic Tube 60mm Ø but the length will be determined by the weight needed and I think that a ‘part filled’ weight would look ‘odd’.

Tomorrow I should start to look at finishing the wooden parts by sanding, applying Sanding Sealer and MC Wax before gluing up the various ‘sets’ of Gears that belong on the same spindle.

 

[donwatson]

Thanks JG

 

[J-G]

8th Jan
First day in the workshop this year - though, to be honest, I have done some ‘fettling’ of the gears while sitting at my office desk and waiting for the PC to finish a task - most of the time has been spent on End-of-Year Accounts and VAT return.

I’ve finished all the CNC machining (well I thought I had! see below) so now it’s a matter of dealing with the surface finish on the Gears and Frame, starting with sanding to 320g, then applying Sanding Sealer, de-nibbing and finishing with MC Wax.

I’d assembled some of the gears/pinions along with their bearings and taking these apart to do the sanding proved somewhat difficult - even though they had not been glued - and one pairing didn’t want to be parted at all and the Pinion disintegrated. With a second, I pressed the bearing deep into the pinion (with a bench press) such that I’ll have to break that apart to retrieve the Bearing — so, I now do have to do some CNC work to make two more!

The ‘fettling’ that I did at my desk was just cleaning up the Gear Teeth. I made a ‘stick’ roughly the shape of the tooth profile, glued a strip of 240g abrasive to it and simply went around each tooth to remove any remnants of wood fiber that would potentially cause a ‘bind’ with the mating Pinion or Gear.

Taking the photo’ for Fig-185 proved ‘interesting’ -- I only have two hands ... but I suspect you can fully understand what I was doing.

9th Jan
Made two new Pinions but scrapped one by trying to take too big a cut when machining the boss so had to make yet another !!

I still have quite a few Gears to ‘fettle’ and although I made another abrasive stick it really is a chore This led me to think about a better option which seemed to be a thin ‘flap wheel’ - or, better still - an abrasive ‘worm wheel’.

To sand the faces I’m using 50mm Ø abrasive discs attached to a pad by Velcro so I’ve had an idea to make a disc with velcro on both sides which will take the same discs. It might be somewhat more aggressive than my ‘Fettling stick’ so will need care but I have found 50mm Ø self adhesive Velcro discs which should be with me early next week so I can soon make a thin double sided abrasive disc which I can mount on a rod in the lathe. I’ll have to punch a 20mm hole in the centre of the Velcro & abrasive but that shouldn’t present much of a problem as I’ve previously made hole punches for Copper & Silver up to 10mm.

12th Jan
All the Gears have now been ‘finished’ with Sanding Sealer and had a final sanding with 400g so now I can start real assembly.

One of the most important things that I hadn’t made were the Escapement Pins so whilst I was waiting for the sanding sealer to thoroughly dry I made these. I had bought in 3m length of 2mm Ø Stainless Steel and had originally determined to hold that in a 2mm Collet on the lathe and feed enough to part off 14mm long pieces but I

had a better idea. To hold the steel in the lathe I would have needed to cut it into shorter (600mm max) lengths and even then by the time I’d parted most of that length off there would have been a short length that could no longer be held but it occurred to me that I could drill a 14mm deep 2.1mm Ø hole in a block of Aluminium and use that to saw off the 120 pins I needed.

I started by using a Jewellers piercing saw but the 4/0 blade was blunt after only 3. They are intended to be used on Silver/Gold/Copper/Brass etc. so there was no real surprise that Stainless Steel took its toll. Once I’d changed to a small Hacksaw I was cutting them off at a regular length in moments. I also needed 24 off at only 10mm long so a second hole soon sorted that and after a mornings work I had all the pins ready to be pressed into the pre-drilled holes.
The shorter pins are for the Drive Gear Pawls and only 6 in each so that’s where I started the assembly. I’d drilled the holes at 1.9mm Ø since I didn’t want to glue the pins in so I considered a 0.1mm interference sufficient. A problem immediately became apparent when I found that I couldn’t hold a pin above the hole and in a position to apply pressure from the Arbour Press so I had to open each hole out to 2mm but only for the first 1mm. Doing this by hand is not the easiest job I’ve had to do and I broke a drill leaving about 2mm in one of the holes That took quite some time to get out! In Fig-187 you can see two of the pins ready to have the third Pawl dropped on.

With the holes widened, I could just press the pin in by hand and then use the Arbour Press to force them in leaving the 5mm height I needed.

My next job will be to put 30 in each of the Escape Wheels but I think I need to find a better way to open the holes in them.

My experience with the Pawl Pins made me think to use the milling machine to ‘carefully’ open the tops of the holes in the Escape Wheel. The potential danger would be that the drill might ‘snatch’ which would remove the grip afforded by the original 1.9mm Ø hole. In fact I found it quite easy to just tweak the top 1mm and after I’d done a few I made sure that the pins would hold. Not remembering how many holes I’d actually re-cut, I continued and found that because these pins are 14mm long, it was easy to hold them well enough to hammer them home into the original holes without using the Arbour Press. One end of each pin was still ‘as sawn’, often with a small burr where I hadn’t sawn quite through

and been able to break the pin off the stock, but I had smoothed the other end off to get it in the jig. This meant that they all needed to be levelled in the same way that I’d sanded the Gears - with the 50mm Ø pad in the mill - but using 60g abrasive with a final skim using 240g.

Fig-188 is the complete Escape Wheel and Fig-189 a close up of the trimmed pins.

13th Jan
The glue-up of the Escape Wheel to the spacer and Pinion can now be done but I’d forgotten that the spacer also needed to be finish sanded & sealed!

The fact that the Spacer and Pinion are already mounted on the spindles made it easy to deal with that but I had to strip them for the glue up and ream the bore again to clean out excess glue.

I’ve received the 50mm Ø Velcro discs and made the thin disc sander that I mentioned on Saturday. Using two, back-to-back, would have been ideal but by the time I have even a thin backing card that the Velcro can be glued to it was too thick so I’ve had to settle for a single sided option and go round each Gear twice - turning them over for the second pass.

The rest of today was spent mostly in glueing together the ‘pairs’ of Gears but also finishing off small details that I hadn’t done on the Winding Drums. I still have to make the cord ends so that’s likely to be tomorrow.

 

[donwatson]

Thanks JG,glad your back.

 

[J-G]

16th Jan
Not a lot done to the clock since my last posting, my workshop lighting has been degrading for some time and although I bought new 600mm Sq. LED Panels in Nov.’19 I hadn’t made the time to fit them. With the demise of two more 5' flourescent tubes (or maybe ‘starters’) last week I really did need to make an effort. Since I’d bought ‘bare’ LED units I had to make ‘fittings’. I knew what they would be - very simple 19 x 45 battens with 16 x 16 trunking set in a slot, screwed to the ceiling so that the LED Panel could be slid in from the end. Exactly the same as those I fitted to my new workshop in 2019.

Nothing ‘fancy’ but deciding what suitable materials I had was, shall we say ‘fraught’! I eventually cut the battens out of some floorboard saved when I re-modelled my bathroom but I ha

d to resort to buying some junction boxes to make the connection to the existing lighting circuit ‘safe’.

I don’t have a fear of electrics - just a sensible respect - but I don’t find working on the ceiling at arms length from a small step ladder the most comfortable and just fitting one panel took me the best part of three days - I had made enough battens for all three lights though, and much of that time was spent in drawing the new LED fitting in the SketchUp model of my property/workshop. I like to know what I’m doing before I start!

I eventually got back to the clock this afternoon but I’ve only made the Cord Ends from 4mm Ø Brass rod. These are quite small at 4mm long and have two holes - one at 1.3mmØ and the other at 2.7mmØ. Fig-192 gives a better idea when compared to a 5p coin.

To drill the holes I needed to make a jig which would precisely locate the small billets in the vice on the milling machine. A small scrap of thin MDF with another scrap of hardwood glued to it did all I needed to position the support in the vice and a 3mm deep slot cut with a ball nose 4mm Ø end-mill was enough to locate the brass billet. I had to change the drill with

out moving the blank of course but that’s no great hardship.

Now the Cord Ends are made, I can get on with finishing the Winding Drums.

17th Jan
The Cord will need to be about 1.5 to 2m long but I can’t be sure of that until I have a fully assembled clock but I do need to start somewhere so I’ll cut them at 2m.

It will be fixed to the Drum by inserting the brass End into a 5mm hole in the side of the Drum (Fig-194) with the Cord coming out of a 1.5mm slot. Keeping it in place will be an End Cap which is fixed with three wood-screws (2mm Ø x 6mm long).

Threading the 1mm Ø (nominal) Cord through the 1.3mm Ø hole proved to be somewhat daunting. In fact so much so that I gave up after nearly an hour of trying various methods - using glue to keep the stran

ds together, thin wire to bind etc. - and drilled it out to 1.5mm, but also widened the outside by using a centre-drill to provide a ‘cone’ which had a tendency to pull the fraying strands ‘in’ rather than push them out. I still had to make a clean cut with a scalpel though.

The Cord is polyester so once threaded through the small hole it becomes a simple matter of burning the end which melts it and forms a larger ‘blob’ to sit inside the 2.7mm hole.

The Endcap had to have the three screw-holes drilled & countersunk before being assembled to the Drum, after which I could run an 8mm Reamer through to clean up any minor irregularity and mount it on the spindle for final finish sanding, sealing, MC wax and polishing.

Fig-195 shows the part assembled Drum with Cord & Cord-End and in Fig-196 you can see the fully assembled Drum with the Cord wound on. The second Cord-End is threaded on but just held on the Cord with a simple knot. It can’t be finished off until I’ve made the Eyelet that will be the top of the Drive Weight. I will have to ‘un-wind’ the Cord because the grub screw that holds it to the spindle is under it and I have to take it off the spindle to glue the Ratchet to the Drum and fit the Main Drive Gear.

 

[donwatson]

Thanks JG