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Juliet
Oct 10, 2018 16:25:39 GMT
Post by GWR 101 on Oct 10, 2018 16:25:39 GMT
Pete, don't knock yourself down they look sound to me. It's all part of the journey to achieving your goal, what are your plans for the crank-pin holes ?. Regards Paul
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smallbrother
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Posts: 2,269
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Post by smallbrother on Oct 10, 2018 17:01:08 GMT
Thanks Paul. They will suffice but the flanges are of variable thickness. I see no reason it will affect the running though so on we go.
I will be making a jig to get the measurement constant. I have some silver steel in my cupboard to make the pins. Hopefully everything will turn reasonably freely when the time comes!
Pete.
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Post by Deleted on Oct 10, 2018 19:32:26 GMT
great work Pete....you'll soon have a rolling chassis, sir...
Pete
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smallbrother
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Juliet
Oct 10, 2018 20:19:11 GMT
Post by smallbrother on Oct 10, 2018 20:19:11 GMT
great work Pete....you'll soon have a rolling chassis, sir... Pete Wonder if I can get there this year. That's my target anyway. Pete.
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Lisa
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Post by Lisa on Oct 11, 2018 3:19:21 GMT
If you read this Lisa I take a lot of inspiration from your posts - thanks for putting them up and please keep them coming. Always nice to know Pete, thanks, and you're welcome. In designing Blowfly, Barry Potter said he took a lot of inspiration from 'an older well known design'; which I'm quite sure was Juliet, as there are a great number of similarities, so it's interesting watching Juliet come together. Keep at it, you'll soon be pushing her back and forth on the bench while making 'chuff chuff' noises... I do it all the time.
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smallbrother
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Post by smallbrother on Feb 6, 2020 12:15:31 GMT
Well a bit of a delay but here we go again. I have cylinders to machine for Juliet and Mona so am doing Juliet first using this video as a guide - www.youtube.com/watch?v=cYeFlDaxMCM&t=606sJust started making a mandrel and come back in the house for a warm-up. Fingers frozen. Pete.
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smallbrother
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Post by smallbrother on Feb 12, 2020 15:00:50 GMT
I have bored out a cylinder and faced one end. (Which of course will be the rear face)
The dimensions of the cylinder vary from 0.998 at the front to 1.002 at the rear of the cylinder. I have taken a lot of measurements as each one can vary depending on how I handle the gauge and the micrometer it would seem.
No massive errors so I am happy with that.
Pete.
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Juliet
Feb 12, 2020 21:33:23 GMT
Post by David on Feb 12, 2020 21:33:23 GMT
Good progress! I agree measuring bores is tricky for us part-timers. Cheap bore gauges like mine probably don't help. They get sticky and I don't really believe anything I read from them. It's easy to imagine the worst outcome of 0.004 to be made up from any number of errors including technique and tools. And that doesn't sound like a huge error anyway.
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Post by Roger on Feb 16, 2020 19:08:23 GMT
I have bored out a cylinder and faced one end. (Which of course will be the rear face) The dimensions of the cylinder vary from 0.998 at the front to 1.002 at the rear of the cylinder. I have taken a lot of measurements as each one can vary depending on how I handle the gauge and the micrometer it would seem. No massive errors so I am happy with that. Pete. Well done Pete, that's an excellent result. You will get variation in your measurements however hard you try to avoid them. The main thing is to get a repeatable close set of values for the measurements you make.
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smallbrother
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Juliet
Feb 17, 2020 8:47:53 GMT
Post by smallbrother on Feb 17, 2020 8:47:53 GMT
Looking a little bit ahead I see the drawing calls for 3 steam passages at each end of the cylinder.
Is this usual and am I reading it correctly I wonder?
Pete.
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Juliet
Feb 17, 2020 9:31:14 GMT
Post by David on Feb 17, 2020 9:31:14 GMT
I think 2 or 3 passages is normal. Consider the vastly greater space in the cutout in the port face compared to one little hole going to the cylinder. High pressure going in might be ok but you probably want some space for the expanded and low pressure exhaust.
I think my mogul has two passages.
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stevep
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Post by stevep on Feb 17, 2020 9:34:53 GMT
Pete, There needs to be a connection between the steam port on the valve face and the end of the cylinder. The normal method of doing this is to drill three holes at the correct angle (making sure the drill doesn't touch the edges of the port. To improve flow, some people then use a small round file and join the three holes so there is rectangular hole with rounded ends. This is how I drilled the holes on one of my Pansy cylinders:
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smallbrother
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Juliet
Feb 17, 2020 9:43:28 GMT
Post by smallbrother on Feb 17, 2020 9:43:28 GMT
Thanks David and Steve.
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Post by Deleted on Feb 17, 2020 10:51:18 GMT
Hi Pete As Steve has stated, the norm is to drill a couple of holes and then open them out to a slot, I did mine a little different, in as I finished the slot with a suitably sized cutter. Here's the picture of the holes being drilled, as Steve showed on his the cylinder needs to be angled for this job. here's the slot after being machined... I must point out, to avoid any confusion, that normally the slot is much closer to the end of the bore, it is so on my outside cylinders. Here I have set it back a little, it's in the correct position in relation to the other end but the bore face is left oversize and a stepped spigot has been incorporated in the cylinder cover to put its inner face in the correct position to match. The reason is the fact that this face has to be machined by hand as you can't get a full swing due to the close proximity of the steam chest, I struggled as it was to swing the chuck, not a fit young man anymore... Pete
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smallbrother
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Juliet
Feb 20, 2020 10:15:51 GMT
Post by smallbrother on Feb 20, 2020 10:15:51 GMT
I have machined the 2 ends and the bore.
Now looking to mill the surface for the steam chest etc.
Not sure how to set this up in the vice as the only references are the machined faces. Not obvious to me how to get things central along the bore in order to get the correct width either side of the centre line.
Will have a little play about.
Pete.
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stevep
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Juliet
Feb 20, 2020 14:17:30 GMT
Post by stevep on Feb 20, 2020 14:17:30 GMT
Pete,
Sorry if this might be a bit disheartening, but I would have machined the port faces (and the bolting flanges) before doing the bores, as it would have given you a reference surface. The port face against one of the 4-jaw jaws (with appropriate packing to avoid marking) would ensure the bore would be parallel to the face.
The challenge you have now is to make sure the port face is parallel to the bore. I am inclined to suggest you hold the cylinder in the machine vice by the front and back faces, with a length of something like silver steel through the bore, and pressed down on the top of the machine vice jaws. That should ensure they come out parallel.
You may be able to do the bolting flanges at the same time.
Hope that helps.
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smallbrother
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Juliet
Feb 20, 2020 15:18:28 GMT
Post by smallbrother on Feb 20, 2020 15:18:28 GMT
Thanks Steve. I assume if I secure the 2 machined faces (with packing) in the vice jaws then the bore will be at right angles to the jaws. I must also ensure the vice is set correctly in the X and Y axes of the mill.
Where I am struggling is to locate the centre line of the bore, so that the port face and flanges are machined equally, either side of the centre line.
If I get this wrong, and the cylinder is a bit high/low, will this cause a problem? Providing the guide bars for the cross-head are parallel to one another and follow the same centre line I am thinking the connecting rod would still operate as it is pinned and can rotate.
Hope this makes sense!
Pete.
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mbrown
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Juliet
Feb 20, 2020 16:29:44 GMT
via mobile
Post by mbrown on Feb 20, 2020 16:29:44 GMT
Hi Pete,
I know you prefer chucking the casting to fly cutting with it on the cross slide, but as you have done the end flanges, another method is to bolt it to the cross slide with a bolt through the bore and the casting resting on the rear end face. Then you can fly cut the portface to a set dimension from the bore and that gives you a datum for milling the flanges. In my view, getting the steamchest precisely aligned with the middle of the bore is less important (within reason) than getting them parallel.
Good luck.
Malcolm
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smallbrother
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Juliet
Feb 20, 2020 16:57:45 GMT
Post by smallbrother on Feb 20, 2020 16:57:45 GMT
Thanks Malcolm.
With careful measurement I reckon I can avoid any gross errors.
Pete.
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stevep
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Post by stevep on Feb 20, 2020 17:03:35 GMT
Thanks Steve. I assume if I secure the 2 machined faces (with packing) in the vice jaws then the bore will be at right angles to the jaws. I must also ensure the vice is set correctly in the X and Y axes of the mill. Where I am struggling is to locate the centre line of the bore, so that the port face and flanges are machined equally, either side of the centre line. If I get this wrong, and the cylinder is a bit high/low, will this cause a problem? Providing the guide bars for the cross-head are parallel to one another and follow the same centre line I am thinking the connecting rod would still operate as it is pinned and can rotate. Hope this makes sense! Pete. Pete, To answer your last question first - not a lot, but it depends on how far out you would be. Don't forget that, as the suspension goes up and down, the centre of the driving axle doesn't remain on the cylinder centre line. My approach to solving your conundrum would be first to machine off the port face with the cylinder in the vice. Then turn up a small piece of material that just fits the bore, and using a small square mark off from each side of the plug to the port face. Do this at both ends, and then scribe a light line to connect the marks from each end. These lines would then be marking the position of the bore. From this, you should be able to mark off the edges of where the flanges should come, and after re-setting the cylinder in the milling machine, mill down to the marks. Provided you haven't marked too hard on the port face, you should be able to polish out the lines by rubbing on a sheet of very fine emery. Otherwise, don't go all the way when you first mill the port face - just clean it up. You can then take it to the final dimension when you do the flanges.
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