Turning a chimney

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Fri Aug 14, 2020 10:50 pm

Another small turning project.
Eccentrics
These are for Great Central loco Kits designed by John Bateson I now have the etch tools and am working my way through some of the turnings which John made for each kit some need to be turned for each kit but other things will go for casting as the time to do one is considerably more than its worth per kit
Starting with an 8mm bar I first face the front.
IMG_5715 (2).JPG

The next step is to drill a hole in the bar, but it needs to be off set from the centre by 1mm. To do this so I have put some spacing brass shim measuring 1mm in one of the jaws of the chuck which off sets the bar by 1mm. ~Then using a pointed milling cutter to start the hole.
IMG_5718.JPG
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This gives me a starter hole. As I need a tight fit on the axle I now use a 3mm drill to drill a deep hole in the end of the bar. Then I will ream out that hole with a 1/8 reamer.
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Once the hole has been reamed out I remove the brass shim.
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Now I reface the front pulling the tool out from the centre then going in again to a pre set distance which I have set at 0 on the cross slide dial.
IMG_5724.JPG

I then move the cross slide forward a set distance of .7mm. Then pull the cross slide out and at the same time the parting tool comes in and parts off the eccentric.
One eccentric turned, repeat this 40 times enough for 10 locos I get 8 off before I have to drill another hole.
IMG_5725.JPG
IMG_5726.JPG


These turnings still need some more work doing to them to make them fit together opposite.
So I have made a small jig to go in the pillar drill Just a brass bar with a 1/8th inch hole in, and a screw to hold the steel rod tight. I have then drilled a second and third hole put some .9mm wire in as a stoppers so that the eccentric when slotted over the rod is pushed against it its always in the right position. The axle hole is aligned with the centre of the chuck of the drill on a compound table, then moved 2.5mm to the left where a .8mm hole has been drilled so that when the eccentric is drilled with .5mm I know when to stop.
IMG_5727.JPG
IMG_5728.JPG

lastly just need cleaning up with a file
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now I have put a set together using a .5mm brass wire and soldered them together
IMG_5748.JPG
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So far I have only done one hole in each the drawing does say to do two to do that all I need to do is turn the eccentric upside down.

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David B
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Re: Turning a chimney

Postby David B » Sat Aug 15, 2020 8:10 am

Returning briefly to having the parting tool at the back and cutting on the 'up', I mentioned this to my brother yesterday (first visit since the lockdown). He is an experienced machinist and said that the main advantage was that the swarf dropped out of the cut instead of collecting on top where it can clog the (narrow) cut.

Another suggestion he gave to this lathe novice was to use a smear of tallow (or candle wax) on a centre drill (or any drill) particularly when drilling something like aluminium or white metal which can grab the bit and snap it. This is more likely to happen with the small diameter drills we use for modelling. The tallow helps to prevent the grabbing by the metal. I have got a drill bit both stuck and snapped in white metal more than once when drilling by hand.

Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Sat Aug 15, 2020 8:48 am

David B wrote:Another suggestion he gave to this lathe novice was to use a smear of tallow (or candle wax) on a centre drill (or any drill) particularly when drilling something like aluminium or white metal which can grab the bit and snap it.


Some sort of cutting lubricant is always needed when drilling steel, but brass and cast iron (which we would rarely if ever use) do not need anything. I have tended to cut aluminium and its alloys dry but on checking a favourite reference source (L.H. Sparey The Amateur's lathe) lubrication is recommended for these metals. Tallow or candle wax is not mentioned but Sparey recommends paraffin, something which not many of us are likely to have about.

Certainly I have experienced drills sticking in white metal so the use of some sort of lubrication is something I will remember. In the absence of anything else, ordinary lubricating oil will make a useful substitute.

Terry Bendall

CornCrake
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Re: Turning a chimney

Postby CornCrake » Sat Aug 15, 2020 9:54 am

Thanks for sharing that process Jeremy, fascinating & informative.
Steve

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Sat Aug 15, 2020 11:17 am

As to lubricants

I don't tend to use any on the big lathe usually only turn brass and nickel silver which don't need it, even steel although it can run hot and could do with a coolant if running it too fast. I use 3ini oil on the pantograph milling machine this keeps the cutters sharp for longer.
In the smaller lathes I only use a dab of spit on the drill bit as a lubricant especially drilling deep holes in brass and any hole in white metal I also move the drill in and out to keep the flutes clear as blocked flutes snaps drills.

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45609
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Re: Turning a chimney

Postby 45609 » Sat Aug 15, 2020 6:57 pm


Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Sun Aug 16, 2020 8:19 am

Jeremy Suter wrote:I don't tend to use any on the big lathe usually only turn brass and nickel silver which don't need it, even steel although it can run hot and could do with a coolant if running it too fast


I would agree with not using lubricant when turning steel, although on larger machine and high speeds it is useful. Just to clarify what I wrote was in relation to drilling holes in steel.

Terry Bendall wrote:
Some sort of cutting lubricant is always needed when drilling steel,


Terry Bendall

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Wed Nov 04, 2020 1:17 pm

Turning Lancashire and Yorkshire Whistles.

I get an order quite regularly for a quantity of these, and they need to be done quickly without mistakes so I use a jig.
IMG_5823[1].JPG

The jig fits in the tail stock and slots over the 1.2mm wire. Its made from an old axle drilled and milled to under just half way. The bottom one is a blank ready to be set for the GWR whistle for my Railmotor kit.
IMG_5842[1].JPG

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They are all done with hand held tools rather than mounted in the tool post.
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Starting with the wire a short distance out of the collet. Actually it is where the last one was cut off.
IMG_5827[1].JPG

Using a shaped lathe tool to do the top and a file to square the end.
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Resting the tool on the tool rest lightly push in and shape the top and then finish with fine emery paper.
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Once the top is done the wire is pulled out and the jig slots over the top, I use a file in the hole at the end to make sure the wire is in the right place.
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Then flip the tool rest over and using a piercing saw in the gaps to mark out the relevant slots.
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Using a 2 cutting edge 3 square file I form the lower section. The none cutting edge against the base so not to cut that part then finish with emery paper to smooth off.
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I use a flat ended tool to form the base.
IMG_5848[1].JPG

Slotting the jig over the wire the base is done with the flat ended cutter against the lower part of the jig which keeps the cutter from cutting the top and putting the base in. The jig also stops the cutter cutting too deep.
IMG_5838[1].JPG

Last job is to polish the whistle with fine emery paper before cutting off with the piecing saw.
IMG_5847[1].JPG

Which leave the wire with a nipple on in just the right place to start again I good run sees it done in about 3 minutes. Just need another 60 now.
https://www.youtube.com/watch?v=eUOUCebKDn4&t=813s
Last edited by Jeremy Suter on Tue Nov 17, 2020 8:17 am, edited 3 times in total.

Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Thu Nov 05, 2020 9:24 am

All very neat Jeremy and you have given me some ideas for future work. The video is well worth watching. The use of a watchmaker's lathe is of course ideal. With a suitable collet and small tool rest, the same job could probably be done on a larger machine. I shall have to give it a try.

Terry Bendall

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Tue Dec 29, 2020 10:26 pm

Turning a chimney in Two pieces

Sometimes it has to be done and this is one of them. I have been asked to do a chimney for a 7mm kit for the SR lord Nelson class and at first glance I thought that would be easy enough. Well I was wrong or it was going to take allot of filing.
My first attempt went well using the methods shown earlier. Until I wanted to cut the flare, the ball cutter was too fat to fit between the top and the section on top of the boiler so I tried a smaller one and thought I would cut less deep.
IMG_5919.JPG

If you look at the picture you can see I have cut too much off along the lower sections or top and bottom in the photo. So I had to start again.
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This time I have machined the base cleaned it up and whipped off the top area leaving a long straight section wider than the inside of the top of the chimney. It still needs work on the flange area to get it to the right diameter of the centre section of the chimney. I also rounded the top to get rid of any interference when I fit the new top.
IMG_5921.JPG

Now I need a new top.
Using the same bar I cut the base from, I drill out a short distance with an 8mm drill about 12mm deep. This gives me a start hole deeper than I need.
IMG_5922.JPG

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Now using a boring bar. I cut the inside of the hole, Its easier if you put the boring bar to the bottom of the hole first then moving it against the side to be cut and drawing the bar out, cutting the side from the bottom to the top rather than the other way round this makes sure you don't damage the cutting tool, and you get a cleaner cut.
I have no internal width gauge other than a pair of callipers so get it to nearly there. Then I take less and less of each cut until the base fits in snugly.
IMG_5924.JPG

In fact I got it so snug I cannot get it out.
So using a round end cutter I took some of the underneath the rim off before parting off with the base and rod slipped in the tailstock to keep it steady.
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Moving it over to the Collet lathe
I have now drawn two lines on the top. the lower one is the top of the rim and the other is the top of the chimney and will start to remove the excess. I have been able to turn the top without the use of solder to hold it. (This was more by luck I was going the solder it on.)
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Finding the diameter of the top. and making a note on the screw index of how far to go in.
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Cutting it to depth small amounts off with each cut.
IMG_5930.JPG

Forming the rim top
IMG_5931.JPG

Forming the rim base Its easier with a file so as not to take too much off in one go.

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Mon Jan 04, 2021 11:02 pm

IMG_5960.JPG
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With the main base shape made I need to add a ring of Rivets to the base of the chimney and to do this without a boiler to sit on I made a plastic box which I could slot the chimney into.
IMG_5964.JPG

I have marked on it the centre line, and the outer radius on each side. Slotting the chimney in I made sure it sits correctly, using a set square. When centred I marked the chimney base centre with a pen.
Putting it back into the lathe, I set that as the first hole. Using a hole jig fixed in the tool post, (its just an old coupling rod soldered to some 4mm square brass rod). It needs to be a little flexible but I will be moving the tool post backwards and forwards so its always close to the part of the chimney base to be drilled.
IMG_5969.JPG

Using the indexing wheel I can set the chuck to 60 positions or in my case 6 by moving it on 10 holes at a time It was later that I
realised I actually needed 12 rivets and had to reset it.
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The drill is resting on a bar to make sure I drill the same angel each time.
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Only done 6 holes at the moment.
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Now I need to start cutting the top this chimney which has a capuchon, and it will be best to remove some of the inside now before starting it.
IMG_5974.JPG

So again into the box to find the centre line of the other plain. Using the centre of the rod I left in, I can lay the set square to find the centre line, although the capuchon needs to go slightly further back.
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Using the lathe tool I have marked out the part to be removed. Twisting the chuck by hand and using the cutter as a scriber I can cut quite deep which gives a good start for the saw slightly above where I need to finish.
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Once marked out I removed the piece with a piercing saw, allowing some filing space to be finished later. I will use the lathe tool again to make sure its level.
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Now the top is cut, I need to remove the centre section. I could use a drill, but as I want a tapered hole I have decided to machine the inside using a home made boring bar, which is ground from 3mm Tool steel, then thinned down to a vee shape so as to not do any damage with the lower edges of the cutter.
IMG_5980.JPG

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I left the middle in for quite a long time so to keep the strength in the joint with the steel rod . Removing it when the inner wall was done.
The chimney is almost finished. It just needs the rivets putting in the base they are made from .5mm nickel silver rod.
IMG_5985.JPG

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When all the rivets rods are in and cleaned up underneath. I now use a piece of scrap brass. A .5mm hole drilled in to go over each rivet head as protection for not filing too much off at a time. Going round once then cleaning off any excess solder and going round another two times taking less off each time as I am filing the guide down a little on each rivet.
IMG_5992[1].JPG

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A few spins in the lathe with the fibre and swede brush will remove any hard edges on the rivets
Last edited by Jeremy Suter on Tue Jan 05, 2021 5:16 pm, edited 2 times in total.

JFS
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Re: Turning a chimney

Postby JFS » Tue Jan 05, 2021 9:12 am

First-rate Jeremy - excellent job and very well explained.
Many thanks indeed for posting.

Best Wishes,
Howard

ralphrobertson
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Re: Turning a chimney

Postby ralphrobertson » Tue Jan 05, 2021 11:32 am

That's a beautiful piece of work Jeremy.

Ralph

Winander
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Re: Turning a chimney

Postby Winander » Tue Jan 05, 2021 1:28 pm

These really are extremely useful demonstrations of techniques and I echo Ralph's observation and thank you for taking the considerable amount of time it must take to share them with us.

What is a swede brush, some kind of rutabaga? Maybe it is a predictive text corruption ;)?

best wishes
Richard Hodgson

Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Tue Jan 05, 2021 2:31 pm

Brilliant. I learn a lot from Jeremy's posts.

Terry Bendall

nigelcliffe
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Re: Turning a chimney

Postby nigelcliffe » Tue Jan 05, 2021 2:58 pm

This is excellent stuff. I particularly liked the support turning tool in the tailstock (I've used a different support method, but will try this one).

Its the sort of thing which needs to find its way into a resource for the future, not lost in the forum archives. As to how, I'm not sure.

CornCrake
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Re: Turning a chimney

Postby CornCrake » Tue Jan 05, 2021 4:47 pm

Wonderful, beats Netflix any time...

Now awaiting sequel,...

"Tuning a whistle!"

Steve

ralphrobertson
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Re: Turning a chimney

Postby ralphrobertson » Tue Jan 05, 2021 6:36 pm

Swede = suede.

Think Jeremy already provided a superb set of instructions on turning a whistle - back up to Jeremy's post on 4 November.

CornCrake
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Re: Turning a chimney

Postby CornCrake » Tue Jan 05, 2021 9:52 pm

Tuning... as in getting the right sound out of them...

Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Wed Jan 06, 2021 9:17 am

CornCrake wrote:Tuning... as in getting the right sound out of them..


But then you would need to make a working valve and have a supply of steam. That would be a challenge. Jeremy and Will L would have to combine their skills. :)

Terry Bendall

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Sun Jan 17, 2021 6:43 pm

My Next project again for the 7mm scale SR Lord Nelson Class is the Smokebox Door.
Like the Chimney it will go for casting. It will fit in a recess in the smoke box front etching.
SB DOOR 2.jpg

So first of all I need to cut a large disc in fact I cut two.
Now putting the block in the lathe I find it is a bit big for the standard Jaws so have taken them out and changed them for the reverse set.
IMG_5993[1].JPG

With the reverse set in. It clamps the metal easily but a block that size and only a small griping area I need to use the live centre to make sure that when I spin the lathe any deviation will not allow the block to be thrown.
IMG_5994[1].JPG

I have cut a large amount off to make a mounting spigot of 6mm and you can see the amount of deviation on the block.
IMG_5997[1].JPG

Because of the diameter of the block. I am using the original tool post for this lathe and have marked off where I want to part it off.
IMG_5999[1].JPG

Parting a block that size is done with a hack saw spinning the lathe I run the saw in the groove, leaving a small section to cut without it spinning.
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With the disc cut off, the jaws changed back and my other tool post put back on I face the front of the disc.
IMG_6006[1].JPG

The first movement now is to put the taper on the front, I have put the original tool post and cross slide on. Not the way the lathe was designed so I had to make it fit, drilling some extra holes in the mount to fit the cross slide at the angle I wanted. As I am only taking small amounts off at a time I used some holes I drilled for an earlier job.
IMG_6011[1].JPG

IMG_6012[1].JPG

Now putting the basic shape in on the smaller lathe.
First I need to get the dimensions. The outer diameter should be 38.4 with a .8mm rim and 1.4mm to the door base.
IMG_6025[1].JPG

IMG_6026[1].JPG

IMG_6027[1].JPG

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Sun Jan 17, 2021 9:00 pm

With the correct diameter of 34.4 mm I have shaped the door's corner using a shaped cutter. I made it that way round on purpose so I can clearly see what I am cutting.
IMG_6039[1].JPG

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This is one of the reasons why I did two disc as this cutter needed to be in the right position for cutting when you look at the chatter on this test part. I also used it for test running the taper cut earlier.
IMG_6037[1].JPG

With the curve on the corner done I need to put it back in the other lathe to do the front to the correct angle and take a little bit more off. The angle I wanted was 7 degrees in fact it is just slightly over which I am happy about, as it gives me some polishing space.
IMG_6040[1].JPG

Now because the top slide is not in the correct position I have had to fudge the angle as close as I can by eye which is one of the reasons I have a test piece. So I can inspect what I have done without touching the work piece.
IMG_6031[1].JPG

When the main shape is done I need to put the rivets in. To do this I have to find the centre for my drill jig which is easily done with a steel centre pin fitted in a 1/8th collet. I made it out of an old EM Axle the spike slots into the hole in the jig, the jig held in the tool post adjusting with the allen key until it moves easily on and off the spike.
IMG_6042[1].JPG

Moving the Drill jig out 6.7 mm from centre I need to mark 10 spacings in 12 positions the 2 nearest the hand rail do not need marking the hand rail is an extra .3mm from centre and not in the 2 missing spaces but just below them.
This is how I held the drill straight to mark the points for drilling.
IMG_6041[1].JPG

This is where I should have concentrated a bit more as I divided 10 into the 60 positions and came up with 6 when it should have been 12 so after marking the 10 positions I had to polished most of them out and started again.
Then moving to the outer rim I mark up the holes for the 8 locking dogs luckily the are all in line with the rivets.
IMG_6044[1].JPG

There is also a secondary lip which is not shown on the drawing I have but can clearly be seen in the original photo of the door which I put in at this point.
IMG_6044.jpg

With the 18 holes marked I now drill them all out with a .6mm drill I also drill out 3 extra with a .4mm to be filled with .4mm wire and filed back to hide the marks I made in error.
IMG_6045[1].JPG

The rivet holes are all now filled with .6mm wire and soldered in from behind.
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Once soldered in I file them back flush on the back and to above the depth they want to be on the front.
IMG_6050[1].JPG

I have left the two Pop marks for the Hand Rail Knobs to be drilled out on the castings.
IMG_6051[1].JPG

Terry Bendall
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Re: Turning a chimney

Postby Terry Bendall » Mon Jan 18, 2021 8:41 am

More very useful stuff from Jeremy. A couple of thoughts ...

When holding a longish length of large diameter bar, a support hole made with a centre drill is useful. This is difficult to do in the lathe. One way is to find the centre of the bar using a centre square and drill the hole in a drilling machine. It needs carful marking our but if you are turning the outside as Jeremy did if the hole is slightly off centre it does not matter a great deal.

An alternative way of setting out holes in a circle is to use a circular table bolted to the table of the drilling or milling machine. These allow the workpiece to be rotated and are graduated in degrees. Small ones, about 100mm diameter are not too expensive but it is an investment which may not be used often.

Terry Bendall

Philip Hall
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Re: Turning a chimney

Postby Philip Hall » Mon Jan 18, 2021 11:30 am

Jeremy, setting out holes in a circle: you can also use the GW Rivet Tool and some calculations. It looks like you have a GW tool and possibly (unlike me) you can handle the trigonometry...

Philip

Jeremy Suter
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Re: Turning a chimney

Postby Jeremy Suter » Mon Jan 18, 2021 5:29 pm

Thanks Terry and Phil for your input.
There are various ways of setting out the holes in the disc the important part is finding the centre and working out from there.

Moving onto the hinges I have made a 3:1 pattern of the hinge for the Pantograph Milling Machine, and cut it out in 10 thou nickel silver sheet.
IMG_6053.JPG

IMG_6054.JPG

Using the same method as before in the lathe I have set the position of the height of the hinges and drilled 4 holes to pin the hinge to the door before I solder them in place, This helps to stop them moving when I cannot touch it.
IMG_6057.JPG

As this is going for casting in a vulcanise mold it has to be able to reach 180degrees without coming apart. So I need to use high melt solder. and something this chunky needs to get very hot I tried with the resistance soldering iron on maximum but would not do it so a used the blow torch.
IMG_6072[1].JPG

With the hinges on I have put a .9mm wire for the bar and wrapped the legs of the hinge round it.
IMG_6058.JPG

The hinge just needs the mount to the smokebox which will be made from a piece of scrap nickel sheet cut to width slotted in the gap and pulled round then soldered in place

With the hinge done the door locking dogs need to be fitted in the 8 holes in the rim.

Again I made another 3:1 pattern of the locks for the Pantograph milling Machine and cut the out in 15 thou nickel they come out allot longer than I need. Two reasons, they don't disappear in the swarf and easier to clean up with something to hold.
IMG_6061.JPG

Now I need a pin to go through the 8 holes I made in the rim which I have done in the 6mm lathe as its the only .8mm collet I have. These need to represent the end of the bolt and the nut that holds the lock down Its a shame I have not got any hexagon stock in that size.
IMG_6060.JPG

As the holes in the locks are too small to do on the pantograph milling machine. I pop marked them and drilled to the right size to fit the rod through, one side folded over and the other cut to length.
IMG_6065.JPG

Once done slotting them in the holes in the rim.
IMG_6066.JPG

Soldered in place and cut back the excess on the other side and file back they should not go as deep as the back as the door as it will fit in a recess in the smoke box front.
IMG_6068.JPG


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