smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
|
Post by smallbrother on Oct 31, 2020 20:20:00 GMT
I am thinking it is quite difficult to get the 1" dimension across the flats correct, with reference to the centre of the hole for the piston rod. I am proposing to make the best effort I can and there is scope to take up any error in the cross-head and slide bars if necessary. Anyone see a difficulty in this approach? Pete/
|
|
|
Post by RGR 60130 on Oct 31, 2020 20:47:35 GMT
I'd machine a bit of bar to 1" diameter with a spigot that's a snug fit in the centre hole. A bit of wetted fag paper on the side of the bar will tell you that you're as good as there when the milling cutter picks it up.
Reg
|
|
stevep
Elder Statesman
Posts: 1,070
|
Post by stevep on Oct 31, 2020 21:28:23 GMT
I do the same, but coat the bar with a marking pen. When the black starts to disappear, you're there.
|
|
|
Post by delaplume on Nov 1, 2020 2:11:08 GMT
Hi Peter,
Yes, as per the 2 ideas--- as a beginner you might find the paper one easier to approach with the tool, the paper being thicker than a pen mark...
Photographic "Tip"}--- For future use, I would have laid a 6" ruler on the table at bottom, L/H of the casting.....or some other technical looking thing.........what the eye doesn't see others can't comment on... if you get my drift ??
Keep it up !!
|
|
smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
|
Post by smallbrother on Nov 7, 2020 15:58:19 GMT
Here is a front cover for a cylinder with the holes centered. I scribed a line with the tool in the lathe to help with marking out. Went much easier with that as a reference - the rear cover I did a few days ago is not as neat as this. ("Yikes", I hear some of you say!) Pete.
|
|
stevep
Elder Statesman
Posts: 1,070
|
Post by stevep on Nov 7, 2020 16:55:24 GMT
Looks good Pete.
The only comment I would make is to ask what gasket material (if any) you are going to use?
I have always relied on metal to metal contact between carefully faced surfaces - and have had no troubles. That deep radial scribe line on the sealing face might leak if you were using metal to metal contact.
I would suggest that in future, you coat the faces with marking fluid, (I use a thick felt pen), and then you can use much less force when scribing the line, and it will show up well.
|
|
|
Juliet
Nov 7, 2020 17:11:58 GMT
Post by delaplume on Nov 7, 2020 17:11:58 GMT
Yes------ as per Steve re}--- marking fluid/felt tip pen etc........works OK and you can keep it in your overalls / dustcoat pocket.......You can now use this cover as a template to spot-through on to the cylinder block...
|
|
smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
|
Post by smallbrother on Nov 7, 2020 18:00:06 GMT
Looks good Pete. The only comment I would make is to ask what gasket material (if any) you are going to use? I have always relied on metal to metal contact between carefully faced surfaces - and have had no troubles. That deep radial scribe line on the sealing face might leak if you were using metal to metal contact. I would suggest that in future, you coat the faces with marking fluid, (I use a thick felt pen), and then you can use much less force when scribing the line, and it will show up well. Very useful tip there Steve. I will be using the usual paper for gaskets so I think they will seal OK, especially as I put a smear of gasket sealant on as well. Pete.
|
|
|
Post by ettingtonliam on Nov 7, 2020 19:18:22 GMT
You might consider adding 2 (3 would be better) tapped holes in the covers for use with jacking screws to get the covers off if you are using gasket sealant. Commonly used in full size practice.
|
|
barlowworks
Statesman
Now finished my other projects, Britannia here I come
Posts: 874
|
Post by barlowworks on Nov 7, 2020 19:29:48 GMT
For blueing I use a chisel tipped blue Sharpie, about £2.50 each from that well known auction site, or about £9.00 for a box of 12.
Mike
|
|
smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
|
Post by smallbrother on Nov 25, 2020 20:38:33 GMT
This photo hides a multitude of sins. I followed the method of one hole drilled and tapped with a fixing screw to hold the cover in place while transferring the holes through the cover to the cylinder. No idea how but the some of the drilled holes managed to shift their position. The register is a good fit. Resolved by filing longer holes but disappointed with the messing about. Will see what I can do to improve on the next one. Have used screws rather than studs. Jury out whether to go to the effort as this is extra work I don't need. This is a front cover and the boss will be removed in due course. Pete.
|
|
|
Post by Deleted on Nov 25, 2020 21:09:33 GMT
Hi Pete
A tip in case you didn't do this, when transferring the holes, after doing the first hole and the bolt is in, next do the hole opposite. It's easier to see that the cover is central, drill/tap and then fit the second bolt. Then the cover is both central and can't move while drilling/tapping the others. I tend to then do the next bolt that's in the middle of the first two and then the opposite to that, I keep doing this until all have been drilled/tapped.
Hope that makes sense?
Pete
|
|
|
Post by delaplume on Nov 25, 2020 21:28:15 GMT
This photo hides a multitude of sins. I followed the method of one hole drilled and tapped with a fixing screw to hold the cover in place while transferring the holes through the cover to the cylinder. No idea how but the some of the drilled holes managed to shift their position. The register is a good fit. Resolved by filing longer holes but disappointed with the messing about. Will see what I can do to improve on the next one. Have used screws rather than studs. Jury out whether to go to the effort as this is extra work I don't need. This is a front cover and the boss will be removed in due course. Pete. Hi Peter, At least those Hex. heads have an "Engineering look" about them--unlike slot headed screws that some folk use.....Flat washers underneath wouldn't go amiss either........ You could always leave the boss on and claim that your loco has balanced pistons fitted............This isn't as daft as you may think..Some full size locos had an extended piston rod running in the front cover....As well as extra load bearing the areas of the piston front and rear are now the same and thus the force exerted is the same forwards and backwards.......A majority of piston valves are set up like this.......
|
|
smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
|
Juliet
Nov 25, 2020 21:52:49 GMT
Post by smallbrother on Nov 25, 2020 21:52:49 GMT
Hi Pete A tip in case you didn't do this, when transferring the holes, after doing the first hole and the bolt is in, next do the hole opposite. It's easier to see that the cover is central, drill/tap and then fit the second bolt. Then the cover is both central and can't move while drilling/tapping the others. I tend to then do the next bolt that's in the middle of the first two and then the opposite to that, I keep doing this until all have been drilled/tapped. Hope that makes sense? Pete Pete - Yes it makes perfect sense and is pretty much what I did. I think I will make deeper holes next time when I drill through. I suspect the drill tip managed to wander - not sure how but the only explanation I can come up with at the moment. Anyway, having done one the next will hopefully be more successful. All good experience! Pete.
|
|
|
Juliet
Nov 25, 2020 22:00:56 GMT
Post by delaplume on Nov 25, 2020 22:00:56 GMT
Hi Peter,
Over time I've made up a collection of Half-length drills......As you can imagine there is virtually no tendency for them to "drift" off course...
|
|
|
Post by Deleted on Nov 25, 2020 22:20:34 GMT
To add to Alan's tip, make sure the drills are sharp...bronze is pretty tough..
Keep up the good work...
Pete
|
|
|
Juliet
Nov 25, 2020 23:01:14 GMT
Post by coniston on Nov 25, 2020 23:01:14 GMT
A good step forward Peter, Hex screws look good and as Alan mentioned a thin small diameter washer under the heads will set them off really nice.
Chris D
|
|
smallbrother
Elder Statesman
Errors aplenty, progress slow, but progress nonetheless!
Posts: 2,269
|
Juliet
Nov 26, 2020 8:53:29 GMT
Post by smallbrother on Nov 26, 2020 8:53:29 GMT
Thanks guys. I was going to put washers on. This is just temporary to see it all fits.
I think I only secured 2 screws before ploughing on with spotting the other holes. I will follow Pete's full procedure for the next one.
Pete.
|
|
stevep
Elder Statesman
Posts: 1,070
|
Post by stevep on Nov 26, 2020 9:15:43 GMT
Thanks guys. I was going to put washers on. This is just temporary to see it all fits. I think I only secured 2 screws before ploughing on with spotting the other holes. I will follow Pete's full procedure for the next one. Pete. I think you answered your own question there Pete - you say you 'spotted' the holes. The tip is to only drill the cover with the tapping size drill. Then when you 'spot' through, use the tapping size drill and go quite deep - even deep enough for the tapping. Then open out that hole in the cover with the clearance drill, and they will definitely be in line. Also, don't forget to mark the cover with which way is up. Unless the holes are drilled with high precision, it will only fit nicely in one position.
|
|
timb
Statesman
Posts: 512
|
Juliet
Nov 26, 2020 10:49:37 GMT
Post by timb on Nov 26, 2020 10:49:37 GMT
Just a thought Pete, dont tighten any of the screws fully until you machine the outer face true. It does not take much of an angle to bend those small bolts and snap the head off. Speaking from experience!
More progress though, well done!
Tim
|
|