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The Workshop Progress Thread 2020

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Ron Laden08/06/2020 12:40:14
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Jason, do I take it that you will fit the liner and then bore it to size and finish on the mill..?

duncan webster09/06/2020 19:20:34
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My timing belt pulleys arrived from China finally, so I've been making swarf for a change. Tailstock DRO now functional, needs a belt guard and the display putting somewhere sensible

img_3781 (small).jpgimg_3780 (small).jpg

JasonB09/06/2020 19:29:15
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Posted by Ron Laden on 08/06/2020 12:40:14:

Jason, do I take it that you will fit the liner and then bore it to size and finish on the mill..?

Probably turn it all in the lathe and then just slip that in to the finned section, might need a bit of a clean up first?

Ron Laden10/06/2020 06:36:42
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Looking good Jason, I see you have it well set up to prevent distortion. Is there much movement when silver soldering steel, I guess a lot depends on the assembly and how much soldering there is.

JasonB10/06/2020 07:08:15
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I've noticed it more on round items like wheels and flywheels where the rim will open up and you also need to watch out if anything is clamped together as the pressure can distort the soft hot metal brass and bronze are more prone to this as you are getting closer to their melting point,

I tray and build in machining allowances on critical surfaces so end up with something like a casting that can then be machined. For example the two horizontal circular parts will have the reduced diameter middle removed which served to keep them in line but reduced mass so they heated quicker, the ends will be skimmed and then holes bored. he two vertical parts of the frame are mostly parallel sides at the moment to make holding for machining easier after which they will be reduced in width but will bulge out around the crankshaft bosses and also have all the corners rounded over.

Neil Wyatt10/06/2020 22:15:38
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Two jobs yesterday, curiously related as they both involved 'Losmandy-style' telescope mounting dovetail plates.

I don't think I've even handled one of these before a few days ago, and then two friends got in touch independently asking me to modify theirs! Both sets dropped off at the garden gate with appropriate social distancing, but good to see some familiar faces.

These plates can be ridiculously expensive, especially red-anodised Italian ones, so it's not surprising that one chap had gambled on a cheap 'no-name' dovetail. The problem was that the distance across the dovetail was at least a millimetre wider than the slot in the saddle clamp it had to fit...

An inspection of a 'proper' dovetail showed that (unlike the narrower, deeper Vixen-style I've made before) it is a 60-degrees, so at least I could use a standard cutter. Offering the cutter up to the cheap plate showed an issue straight away - it was cut at nearer to 70 than 60 degrees. That's why the distance across the dovetail didn't seem much oversize yet it clearly was nowhere near fitting.

I should have skimmed both sides, but the problem was that it's around 400mm long and that meant interrupted cuts anyway. I decided just to skim 1.5mm off one side. The slots made it easy to clamp although I could only use M6 screws, and I had to remove the Y-handwheel and rely solely on power feed. I used block against the t-slot for alignment.

Locking the Y-axis the Bristol handle broke - and it was a 'superior' replacement for the one originally fitted. I swapped the handle off an M5 one to get it going again, but I'm going back to using a cap head screw and a t-handle Allen wrench...

I decided better t take a light skim off the flat than end up with a step inside the dovetail vee, but it was a fairly light cut.

I'd forgotten that some time ago I fitted a 1A fuse as a 'get running' bodge, so 40mm into a cut under power feed it blew... (for the record I was climb milling on my X2).

But I had a pack of the correct (I hope) 3.15A fuses and managed to complete the first cut. I then moved it along again using blocks to set it. As I feared despite care being taken to get the same Y setting, I got a very slight bump at the join. But this is just a clamping dovetail, not a working surface so that's not a problem.

I also discovered a second reason why these plate are cheap - the countersink holes are FAR to widely spaced and my cut just broke into the countersinks at the base of the dovetail. Even if machined symmetrically there would only have been about 0.25mm between dovetail and countersinks...

Naturally there are machining witnesses where the mill stalled and at the join, but you can't really feel them.

I broke all the sharp edges and it's now a nice fit in the dovetail clamp.

losmandy dovetail 1.jpg

The other friend's pair were a budget set, and the irony was that the countersunk holes were too close together, by about 4 or 5mm, for expensive red tube rings! Not necessarily a fault as different manufacturers use different spacings. The chap is ex-Royal Engineers, but although his expertise was building bridges in Iraq at 40C in the shade he was still able to accurately mark out the positions for four holes on each dovetail.

This was a much easier job, and the drill press was up to the task. I picked up each of his marks with a spotting drill. the holes were an odd size (meant as clearance for both M6 and 1/4" UNC - camera tripod thread). It was rather less than 7mm and the closest match I could find was letter I, which I followed up with. Deburrd the exit wounds and a test against the tube rings showed all was well. They are countersunk M10, and while strictly they should be flat bottomed, rather than risk a mishap I just followed up with a quality M10 bit and used the depth stop on the drill press, then deburred the top.

losmandy dovetail 2.jpg

The moral of this story?

If you're a member of an astro club, don't let on that you have a workshop!

Neil

Joseph Noci 110/06/2020 22:48:21
711 forum posts
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Posted by Neil Wyatt on 10/06/2020 22:15:38:

The moral of this story?

If you're a member of an astro club, don't let on that you have a workshop!

Neil

If you're a member of an astro club life, don't let on that you have a workshop!

Joe

Jim Nic11/06/2020 20:26:02
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A "family shot" of progress so far on my version of Stew Hart's Dads & Lads mill engine.

family 1.jpg

The governor is a Bangood special .

There's still plenty to do; when I've got the eccentric and flywheel done I will look to getting the crankshaft drawn up so that I can fit a driving pulley that lines up with the governor.

Jim

Chris Gunn11/06/2020 20:45:22
327 forum posts
24 photos

Here is my Undertype now painted and with a tiled and bricked plinth. I used printed glossy tile paper and embossed brick effect paper, but I should have done it Jason's way, as the oil from the engine is working its way under the paper. Chris Gunnp6114015.jpg

Iain Downs29/06/2020 08:10:15
667 forum posts
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Nothing as nice as some of these models, but this weekend I completed a spindle lock for my mill

spindlelock.jpg

As usual for me, the original idea (to have the legs a snug fit to the DRO link) failed, due to slight inaccuracies in the centering of the block on the cylinder. Bodging didn't work, so I ended up reversing the block and putting some set screws in.

It's now helped to make some keyways for me.

Iain

JasonB12/07/2020 14:03:29
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My Thompson engine has been steadily progressing. All the gears are in place complete with cam and coolong fan, crankshaft done as well as the liner and piston. Yesterday I shape dthe head on the CNC and this morning did the valve and inlet/outlet holes.

Edited By JasonB on 12/07/2020 14:05:32

Ron Laden12/07/2020 15:13:35
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Looking good Jason, especially the frame considering it came from flat stock, you could certainly be forgiven from thinking it a casting. Also impressive is the alignment considering it a silver soldered assy, not the easiest of shapes but obviously proves your initial set up was good.

Ron

Jim Nic13/07/2020 12:29:34
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Slowly but surely I'm creeping up on Stew Hart's Dads & Lads mill engine. Here is the connecting rod before I make the big end bearing:

conn rod 2.jpg

This is the flywheel "Wot I made.":

flywheel 2.jpg

And here's the bits completed so far loosely put together:

family 3.jpg

Jim

mechman4813/07/2020 16:06:34
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Oh woe is me! got back to my beam engine again after some away time, as previously mentioned, on assembly of earlier parts I noticed tight spots appearing in parts when assembling. one was in the piston operation within the cylinder, I had to strip the piston out & check the bore as there seemed to be a tight spot in the centre of the cylinder ( ? ) don't ask! I ended up giving the cylinder a little extra hone in the middle area to see if that would improve matters, the piston seemed to move easier than before.

I reassembled the cylinder & valve chest assembly together & tried operation with compressed air, it seems to work pretty smoothly, the piston reaching both ends of the stroke when I operated the slide valve so I know that works ok, but when I assembled the eccentric conrod to the bell crank it would not operate through its full rotation. I checked & freed off the end of the conrod yoke where it was catching the bell crank by some judicial filing but still catching as though the conrod was too long & not allowing eccentric full rotation.

I chanced removing a couple of threads from the conrod to see if that would help eccentric go 'over centre' no chance ! finally looked at the crankshaft end; lo & behold .. a run out on one side if the crank. on stripping it out again I checked distance between webs, all as should be but closer inspection showed that the eccentric side of the crank the shaft was not 90* to the web... hmm? it boils down to prior making of the crankshaft the drilling for the 4mm diam portion was not vertical to the web, if you get my drift. Suspicion fell on to the culprit as being the bench drill not being as accurate as hoped ..bearing fit etc.so in essence drilling off the vertical, so in all it was giving me a run out of 0.024" on the right hand side of the crankshaft & locking up the eccentric side plates & over reaching the con rod stroke, Bollocks was my cry!

Needles to say I am now again at the remaking of the crankshaft / webs stage, this time I'll make the crank up as a single rod through the offset ( big end ) & the web end rather than as shown on the drawing as separate pieces; & I'll do the drilling on the mill.

Crank zeroed at 'low spot' ... NB. felt tip marked at top of crank...

27.crank shaft run out (3).jpg

Crank rotated 180*... .024" run out ... not good!

27.crank shaft run out (4).jpg

Ah well! .. Mea Culpa,... "Once more into the breach" is all I can say.

George.

JasonB19/07/2020 17:03:30
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I picked up this piece of 105mm dia EN3 and put it onto the KX3's table briefly stopping at th elathe on the way.

And a little while later pick this up leaving behind a pile of swarf. Not too bad but there are a couple of things I'm not totally happy with so will look into what caused them before doing the next one.

Edited By JasonB on 19/07/2020 17:05:58

Ron Laden19/07/2020 19:41:34
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That is a heavy duty looking wheel Jason, never imagined the Thompson would have such a thick set wheel but then I looked back at the original engine picture and saw it has a real lump of a flywheel.

JasonB19/07/2020 20:18:59
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I thought a spoked one would look nicer, still got a big hub so the starter cord pulley can be fitted to that. Hopefully will make for some nice slow running. I wanted something that looked a bit like the flywheel on a Wall Wizard

Ron Laden20/07/2020 03:25:54
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1970 forum posts
390 photos

The Wizard wheel does look good and going by the pictures the spokes look a bit slimmer though it has 6 spokes against your 5. I,m guessing it is something about the spokes you are not happy with, is it possible to put the wheel up again and have enough meat to machine out the problem or is it not that simple or even doable.

Ron

Roderick Jenkins23/07/2020 17:39:09
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OK, I know it's only wood but it did come out of my workshop:

bglr1.jpg

bglr2.jpg

bglr3.jpg

Baroque guitar cobbled together from drawings of a Jacopo Checchucci and an Antonio Stradivari. Birds-eye Maple, Ebony and Alpine Spruce. It's tuned like the top five strings of a modern guitar except the D string is paired with one an octave higher and the A strings are both an octave higher.

Stay well,

Rod

Colin Heseltine23/07/2020 19:21:18
419 forum posts
125 photos

Rod,

That is very nice work. I'm intrigued by the frets are they movable>

Colin

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