Author Topic: Colin Thorne's - Skeleton Timepiece (Read 33519 times)

sbwhart · « **Reply #25 on:** November 14, 2009, 04:59:51 AM »

Chris

You need to get them exactly all the same length or the frame will be twist when you tighten things up.

Best way is to use a back stop.

Stew

raynerd · « **Reply #26 on:** November 14, 2009, 06:25:19 AM »

OK - so if I make a little jig with a 6mm hole, push the jig up to lock up against the back of the chuck and then insert a pillar. Take it down to a perfect size, lock up the saddle and repeat with each of the pillar? I`ll let you know how it goes. They currently measure 45.00, 45.20 and 45.20 so they are not exact.

EDIT: I was just reading this: http://madmodder.net/index.php?topic=1649.15 and unfortunately that would work as the critical size is shoulder to shoulder not end to end.

sbwhart · « **Reply #27 on:** November 14, 2009, 07:11:53 AM »

Thats correct Chris shoulder to shoulder is the critical feature, your little jig idea would be just the ticket.

Have fun

Stew

raynerd · « **Reply #28 on:** November 14, 2009, 07:21:24 AM »

something like this:

Will it be accurate enough when repositioning each pillar as I will need to remove the jig from the jaws to unbolt it, or I could try and leave it in place and use a long screwdriver on my mini lathe? If I punch the jog to locate jaw 1 would that be good enough?

raynerd · « **Reply #29 on:** November 14, 2009, 08:08:16 AM »

... it may be as accurate turning between centres and measuring them as I go and taking my time?? I`ll give it a think before I do anything, they are easy enough to make but wouldn`t like to waste my time for the sake of it.

Chris

raynerd · « **Reply #30 on:** November 16, 2009, 06:53:41 PM »

A slight aside from the actual clock build, after seeing Jere's watch box for all his parts as he makes them I couldn`t help but want one. Certainly not to Jere's high standards but should serve me well in my dirty workshop! I have made a compartment at the front large enough for the frame and the first row is sufficient size for the larger wheels. I`ve been planning this all weekend and it hasn`t taken me too long to finish...

Last picture is with it up to date!!! Hummm

a bit empty, perhaps I should now get on with the difficult part of building a clock! .... nope, not yet, a few more clock related jobs and tools to make! Keep posted....

Chris

Bernd · « **Reply #31 on:** November 16, 2009, 07:39:33 PM »

Chris,

Nice box.

It'll even nicer once you fill it up with the parts you make for the clock. Can't wait to see when the box is full.

So now, get to work.

Bernd

Krown Kustoms · « **Reply #32 on:** November 17, 2009, 08:46:16 AM »

It looks good, I like the box.
I collect watches (mostly modern), I have a box similar for them.
-B-

zeusrekning · « **Reply #33 on:** November 17, 2009, 05:25:01 PM »

Awesome work Chris, I had toyed with the idea of attemping this clock a while back. But Im happy to settle with watching you do it instead. But im impatient so

Tim

Cliff · « **Reply #34 on:** November 17, 2009, 11:40:13 PM »

Awesome build Chris. Cliff.

raynerd · « **Reply #35 on:** December 01, 2009, 03:26:16 PM »

I`m cheesed off, I`ve just taken a nice video of me cutting the wheel with my new CNC rotary table and the damn file won`t open! It says the file is corrupt or different format. All the other videos will open so I haven`t a clue why this one won`t!

Anyway, it’s not as exciting but here are a few pictures and it is much more successful than last! I`m really pleased. Here is what has changed since my last attempt:

1. Clockmakers CZ120 engravers brass, I would never bother trying with soft brass again!!
2. A new sharp hardened cutter
3. My new CNC rotary table which worked a treat!

I`m really pleased. I`m going to re-do it as I still feel the teeth are a touch spiral which indicated my cutter was not centre. I spent a good 10 minutes eyeballing this centre with a dead centre in the rotary table and locking the Z-axis to position. I`m certain it was centre so I need to work out what was wrong, perhaps the cutter is not sitting parallel?

It could possibly run as it is only a fraction out and barely noticeable but I think I`ll go for a re-make. Just need to figure how to get this bob on centre height.

These pictures are still on the rotary table with the teeth just cut. They have since been dressed and cleaned up. The difference is the flakes that are still on the photos just flick off and rub off with fine paper where as with the soft brass in my last attempt at cutting, the brass flakes left behind were smudged and could not be cleaned. I`m not going any further with this wheel yet as I would prefer to start over a fresh but I`m confident the tooth profile is OK so the cutter seems a success.

Chris

raynerd · « **Reply #36 on:** December 01, 2009, 03:28:44 PM »

The thread to my CNC rotary table conversion is here:

http://madmodder.net/index.php?topic=2242.0

it was built primarly for this project and seems like it is going to work perfectly.

Chris

sbwhart · « **Reply #37 on:** December 01, 2009, 04:08:24 PM »

Nice going Chris.

A height gauge may help you get the tool at the correct height, this is how I got the key way tool set for a pulley I was making.

Hope this helps.

Stew

andyf · « **Reply #38 on:** December 01, 2009, 05:09:39 PM »

I still reckon that, if you are cutting each space to full depth before moving round (for example, clockwise from your viewpoint) to cut the next, the brass on the left side of the space you are cutting will be better supported than the brass on the right of it (because you have already cut a space on the other side of the brass to the right, whereas there is no space to the left). Thus, the stresses of the cutting might be causing the brass on the right to bend over a little into that existing space, giving the spiral effect.

Andy

Darren · « **Reply #39 on:** December 01, 2009, 06:47:36 PM »

I think Andy has a good point ..... you are coming on well there Chris ...

sbwhart · « **Reply #40 on:** December 02, 2009, 01:59:02 AM »

Chris

Andy as made a good point, did you use a backing plate the extra thickness and support may stop that effect, also it may be an optical illusion, but the teeth look thinner than the gap they should be about the same, have you measured them ?.

Did you start with the largest wheel, that way if you get a scrapper you can reduce its dia down to the next smallest and not waist the material.
(you may end up with lots and lots of tiny wheels

)

Just a leg pull

Have fun

Stew

raynerd · « **Reply #41 on:** December 04, 2009, 04:57:01 AM »

Hi Guys

I`ve just been with someone who has cut out some wheels and using 2.5mm combo brass which this is, you really shouldn`t need any support or backing plate. I`m not going against your advice and theory, it sounds totally likely but with this thickness of brass it seems unlikely that the teeth will bend. In my first attempt the brass was very thin and with thin brass in future wheels I will definately back them. However, I can understand how backing plate will support the teeth from pushing backwards but not bending to the right. The advice is to take the cut in one pass at full depth. It was quite a quick clean cut and I can`t see much pressure pushing the teeth sideways, I would expect it all to be against the cut.

Stew, the gaps are a touch wider than the teeth but I`ve been told that I should get away with this with lantern pinions.

I think it may be worth making a lantern pinion and depthing the two out to see if I get a correct meshing?

Chris

Stilldrillin · « **Reply #42 on:** December 04, 2009, 08:55:01 AM »

Quote from: craynerd on December 01, 2009, 03:26:16 PM

I`m really pleased. I`m going to re-do it as I still feel the teeth are a touch spiral which indicated my cutter was not centre. I spent a good 10 minutes eyeballing this centre with a dead centre in the rotary table and locking the Z-axis to position. I`m certain it was centre so I need to work out what was wrong, perhaps the cutter is not sitting parallel?

Chris

Chris,
It looks to me as though your cutter was below centre height.

Try my setting method, used over very many years........

http://madmodder.net/index.php?topic=1904.msg22777#msg22777

David D

raynerd · « **Reply #43 on:** December 04, 2009, 02:49:59 PM »

David, call me thick but I`m not 100% sure I`ve got the method right. What do you mean by "take a light cut across the blank, at the rear of the indexer.

Rotate blank 180 degrees.

Then take a same depth, but partial length cut across the blank, at the front of the indexer."

Will you end with marks on the blank? I can kind of understand what your doing, your taking a cut then shifting it 180 deg and if it is not on centre you`ll end with two marks rather than one mark on the same position right? I`m just not 100% sure of your method.... any more ideas.

Chris

dsquire · « **Reply #44 on:** December 04, 2009, 05:35:35 PM »

Chris

~~I think he means to flip the blank 180 degrees then take a partial cut to see if they line up.~~
Cheers

Don

Reason for edit: Wrong advise given. Don

Stilldrillin · « **Reply #45 on:** December 05, 2009, 04:35:16 AM »

Chris,

Take a light pass, (make a witness mark), in your chosen cutting position......

Rotate blank/ indexer 180dgrs.

Don`t disturb Z. Move cutter in Y axis, to align with the mark you made, in it`s new position.

Observe cutter position relative to existing mark.

Adjust in Z axis until this process produces only 1 witness mark, in both 180dgr positions of the indexer........

MUCH easier to do, than to explain!

David D

raynerd · « **Reply #46 on:** December 05, 2009, 12:14:30 PM »

Makes perfect sense now, cheers Dave. That is a great idea. Basically, if it isn`t centre it`ll make two marks instead of one - got ya!

Chris

Stilldrillin · « **Reply #47 on:** December 05, 2009, 12:25:00 PM »

Quote from: craynerd on December 05, 2009, 12:14:30 PM

Makes perfect sense now, cheers Dave. That is a great idea. Basically, if it isn`t centre it`ll make two marks instead of one - got ya!

Chris

Thas right!

raynerd · « **Reply #48 on:** January 15, 2010, 03:23:52 AM »

A bit of an update - not much but the frame is now cut and this is the first assembly. I need to square the bottoms of the frames. Camera phone so not the best quality:

sbwhart · « **Reply #49 on:** January 15, 2010, 04:48:44 AM »

Looking good Chris

Have fun

Stew

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Author Topic: Colin Thorne's - Skeleton Timepiece (Read 33519 times)