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Post by delaplume on Mar 4, 2020 22:32:01 GMT
Hello all,
Quote}---" may also need to put a notch into the spigots on the cylinder covers too."........Yes, quite agree...Down the many years repairing and / or overhauling various different designs for people this problem has cropped up on more than one occasion....Solution as given.
Those "Interesting marks" are high spots....
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Post by keith1500 on Mar 4, 2020 23:59:19 GMT
Indeed I agree those interesting marks are high spots but isn't it strange that there should be high and low spots given it was bored out by a rotating tool. Are they the result of vibration in the tool? Is this common?
Just out of curiosity, what would be the symptoms that can expect for this engine if I don’t provide it with good steam access above the piston when it’s at the end of its stroke?
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jasonb
Elder Statesman
Posts: 1,209
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Post by jasonb on Mar 5, 2020 7:27:55 GMT
Indeed I agree those interesting marks are high spots but isn't it strange that there should be high and low spots given it was bored out by a rotating tool. Are they the result of vibration in the tool? Is this common? Just out of curiosity, what would be the symptoms that can expect for this engine if I don’t provide it with good steam access above the piston when it’s at the end of its stroke? It would still run a sit is, and unless you are looking for efficiency and performance probably won't hake a lot of difference, maybe just a bit lumpy at slow speed running as the exhausted air can't get out so easily and not helped by the lack of air getting in at the other end. Your smaller size holes may also be part of the reason there is less exposed opening, Think you drilled 1/8" rather than 3.5mm on the drawings.
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Post by delaplume on Mar 6, 2020 20:56:50 GMT
What lap is there ??.......if you are working expansively then there isn't any steam access at the end of the stroke..........Unless you are referring to the LEAD steam on the other side of the piston ??
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Post by keith1500 on Mar 29, 2020 18:13:30 GMT
Started to machine the valve arrangement.
The steam chest as such is a bronze cylinder with a 7mm reamed hole. I am just in the throws of drilling of the 7mm hole and dreading the thought of reaming it, why?
Started with a 5 mm pilot. Went well. Next was a 6.5 mm drill which started to get hot and grab. Swapped for another. Same issue. Resharpened a drill with plenty of clearance. This worked better. But I have stopped half way down as the job is getting too hot.
What the technique/ approach with bronze?
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Post by Roger on Mar 29, 2020 19:54:27 GMT
Bronze is a natural bearing material, and as such, it would much rather rub than cut. You need razor sharp tools to cut it cleanly and without getting very hot. You don't need a high RPM, slow and gentle is the way in my opinion. If you think about it, the 5mm pilot had a much tougher job than opening it out a bit with the 6.5mm drill, so it has to be the sharpness and geometry of the 6.5mm drill that's not right. I always use flood coolant on all lathe operations, that helps no end, even on Bronze or Brass which people usually say doesn't need any. The only material I wouldn't use coolant on is Cast Iron.
I'd open it up to 6.8 then 6.9 before finally reaming 7mm.
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Post by Oily Rag on Mar 29, 2020 20:54:11 GMT
Started to machine the valve arrangement. The steam chest as such is a bronze cylinder with a 7mm reamed hole. I am just in the throws of drilling of the 7mm hole and dreading the thought of reaming it, why? Started with a 5 mm pilot. Went well. Next was a 6.5 mm drill which started to get hot and grab. Swapped for another. Same issue. Resharpened a drill with plenty of clearance. This worked better. But I have stopped half way down as the job is getting too hot. What the technique/ approach with bronze? Did you break the edge of the drill with flat of .20mm for use in bronze ? Opening out a hole with a normal sharp drill will more likely snatch than not snatch ! Try this. I have a full set of drills for such tasks. [/font
www.youtube.com/watch?v=pAngKHIZgyA
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Post by keith1500 on Mar 29, 2020 21:31:35 GMT
Next time I am in Brisbane I’ll buy you a beer.
So treat bronze the same as brass?
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Post by Oily Rag on Mar 29, 2020 21:46:01 GMT
Next time I am in Brisbane I’ll buy you a beer. So treat bronze the same as brass? Yes ATMCO (according to my current opinion) especially opening out a hole and breaking through the other side. Always welcome if any one is in Brisbane, call in for a feed , beer and wine.
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Post by delaplume on Mar 29, 2020 22:07:51 GMT
Started to machine the valve arrangement. The steam chest as such is a bronze cylinder with a 7mm reamed hole. I am just in the throws of drilling of the 7mm hole and dreading the thought of reaming it, why? Started with a 5 mm pilot. Went well. Next was a 6.5 mm drill which started to get hot and grab. Swapped for another. Same issue. Resharpened a drill with plenty of clearance. This worked better. But I have stopped half way down as the job is getting too hot. What the technique/ approach with bronze? Did you break the edge of the drill with flat of .20mm for use in bronze ? Opening out a hole with a normal sharp drill will more likely snatch than not snatch ! Try this. I have a full set of drills for such tasks. [/font
www.youtube.com/watch?v=pAngKHIZgyAExcellent link---thanks very much ----I'd forgotten all about that idea ----- That's given me something to do during this virus lock-down..... As a Pom I'd naturally love to join you for a feed, beer and a whine !!-------------LoL !! Cheers.
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Post by Roger on Mar 29, 2020 22:30:55 GMT
Started to machine the valve arrangement. The steam chest as such is a bronze cylinder with a 7mm reamed hole. I am just in the throws of drilling of the 7mm hole and dreading the thought of reaming it, why? Started with a 5 mm pilot. Went well. Next was a 6.5 mm drill which started to get hot and grab. Swapped for another. Same issue. Resharpened a drill with plenty of clearance. This worked better. But I have stopped half way down as the job is getting too hot. What the technique/ approach with bronze? Did you break the edge of the drill with flat of .20mm for use in bronze ? Opening out a hole with a normal sharp drill will more likely snatch than not snatch ! Try this. I have a full set of drills for such tasks. [/font
www.youtube.com/watch?v=pAngKHIZgyAI certainly agree that it does have a tendency to grab the drill. However, if you're aware of this and you lightly pinch the tailstock you'll find that there's no need to modify the drills, although this undoubtedly does work. Just take it gently and it will be fine.
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Post by keith1500 on Apr 1, 2020 8:56:00 GMT
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Post by Roger on Apr 1, 2020 13:05:41 GMT
Hi Keith, From the colour of that, I'd say it's possibly Phosphor Bronze PB102 or similar? If it turns leaving stringy swarf then it's probably Phosphor Bronze, because most other Bronzes break up a bit like Brass. If it's Phosphor Bronze, I approach machining it as I would Stainless Steel, ie with polished inserts as used on Aluminium or HSS with a decent amount of top rake. I definitely wouldn't use a general purpose insert or break the edge of a drill as has been suggested for Brass or Bronze. Again, if it's PB102, unless the Reamer is really sharp it will rub, get very hot and possibly jam up. In other words, all Bronzes are definitely not the same. Some machine more like Brass, and other like Stainless Steel. Another thing to watch out for is that if you buy material from eBay, many of the sellers list Phosphor Bronze and then tell you it's SAE660 which definitely isn't Phosphor Bronze. You have to look for PB102 or PB104 to be sure of getting the right thing.
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Post by keith1500 on Apr 1, 2020 14:42:42 GMT
Hi Roger,
That probably explains it! From what you have said I think you have hit the nail on the head.
I guess it helps to know what you are dealing with in the first place! Thanks for the heads up on that.
As I haven't got a 7mm reamer I’ll make sure I get a new one.
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Post by andyhigham on Apr 1, 2020 18:01:55 GMT
Hi Keith, From the colour of that, I'd say it's possibly Phosphor Bronze PB102 or similar? If it turns leaving stringy swarf then it's probably Phosphor Bronze, because most other Bronzes break up a bit like Brass. If it's Phosphor Bronze, I approach machining it as I would Stainless Steel, ie with polished inserts as used on Aluminium or HSS with a decent amount of top rake. I definitely wouldn't use a general purpose insert or break the edge of a drill as has been suggested for Brass or Bronze. Again, if it's PB102, unless the Reamer is really sharp it will rub, get very hot and possibly jam up. In other words, all Bronzes are definitely not the same. Some machine more like Brass, and other like Stainless Steel. Another thing to watch out for is that if you buy material from eBay, many of the sellers list Phosphor Bronze and then tell you it's SAE660 which definitely isn't Phosphor Bronze. You have to look for PB102 or PB104 to be sure of getting the right thing. Also beware if you get bronze from an unknown source it could be "aluminium bronze" That is a real bitch to machine, it is really hard and fights back
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Post by Roger on Apr 1, 2020 18:53:02 GMT
Hi Keith, From the colour of that, I'd say it's possibly Phosphor Bronze PB102 or similar? If it turns leaving stringy swarf then it's probably Phosphor Bronze, because most other Bronzes break up a bit like Brass. If it's Phosphor Bronze, I approach machining it as I would Stainless Steel, ie with polished inserts as used on Aluminium or HSS with a decent amount of top rake. I definitely wouldn't use a general purpose insert or break the edge of a drill as has been suggested for Brass or Bronze. Again, if it's PB102, unless the Reamer is really sharp it will rub, get very hot and possibly jam up. In other words, all Bronzes are definitely not the same. Some machine more like Brass, and other like Stainless Steel. Another thing to watch out for is that if you buy material from eBay, many of the sellers list Phosphor Bronze and then tell you it's SAE660 which definitely isn't Phosphor Bronze. You have to look for PB102 or PB104 to be sure of getting the right thing. Also beware if you get bronze from an unknown source it could be "aluminium bronze" That is a real bitch to machine, it is really hard and fights back You can see the difference in colour though, it has a lighter yellow hue if its Aluminium Bronze. Again, it machines more like Stainless Steel than most Bronzes, and it's usually more expensive. I made my valve crosshead from Aluminium Bronze because it's much stiffer than the SAE660 leaded bronze. As long as you understand what it's like to machine, it's not a problem if you have razor sharp tools with plenty of top rake and lubricant. Now, if you want something that's a real bitch to machine, look no further than Molybdenum. That stuff detroys tools like nothing else I've ever machined. You might get half a dozen cuts out of a tap or die, then you throw them away. It's abrasive, brittle and you can only take tiny cuts. Truly horrible.
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Post by keith1500 on Apr 1, 2020 20:43:50 GMT
Well, this bronze might well be aluminium bronze. The swarf coming off the lathe is similar to that when machining aluminium, certainly not chipping like brass.
Oh, well we have started so we’ll finish ! The next job is a couple of holes and then machine a shallow slot. Watch this space.
As goes for Molybdenum, I just Wikipedia that, I can not imagine ever having to come across it other then as an additive in something special like a steel. It reads like a subject that would pop up on mastermind.!
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Post by Roger on Apr 1, 2020 21:15:08 GMT
Well, this bronze might well be aluminium bronze. The swarf coming off the lathe is similar to that when machining aluminium, certainly not chipping like brass. Oh, well we have started so we’ll finish ! The next job is a couple of holes and then machine a shallow slot. Watch this space. As goes for Molybdenum, I just Wikipedia that, I can not imagine ever having to come across it other then as an additive in something special like a steel. It reads like a subject that would pop up on mastermind.! No, I'm sure it's Phosphor Bronze if it turns with long stringers of swarf. You say it turns like Aluminium, but I bet it's more difficult to turn ie it takes more force to cut. Take a look at this photo. The bar on the left is Aluminium Bronze, and the one on the right is Phosphor Bronze PB102. Yours looks like the colour of the one on the right. Aluminium Bronze could be mistaken from Brass until you try to machine it. 20200401_220957 by The train Man, on Flickr
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Post by springcrocus on Apr 2, 2020 6:08:46 GMT
I accidently made some boiler bushes from ali-bronze and had to bin them. It's the colour of brass, turns like stainless and doesn't accept silver solder, well not with ordinary fluxes. Based on a comparison of the colour of your component against your brass base part in the photo, I would agree with Roger. It's phosphor-bronze and will need very sharp tools to machine.
Regards, Steve
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Post by keith1500 on Apr 2, 2020 21:36:17 GMT
Found some time to do a bit more on the valve body. Two items. The first was the two exhaust steam ports and corresponding slot that links them to the exhaust steam pipe. The other was to make the brass cap. To this I added an O ring which should ensure a good seal with minimum force, after all there’s not much to prevent the valve body from rotating other than a dose of locksomethingtight. Simple single cylinder steam engine by GL5Keith1500, on Flickr A picture for the curious showing the valve body in situ minus the cylinder block. Simple single cylinder steam engine by GL5Keith1500, on Flickr
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