|
Post by William A on Feb 23, 2022 20:58:03 GMT
I'm encouraged - I've put the refundable deposit down with Western Steam though; I figure I can't lose on that one really and I've probably got another year or so before I even really need to sweat it. Andrew at B/H has also kindly offered advice and assistance which I will definitely take up.
In terms of wider goals I am first looking to get the locomotive as a rolling chassis - requires finish machining the horns (they are slightly tapered) and fitting the hornstays, fabricating the axleboxes, bogie pin, and a ton of 3BA bolts.
Once that's done I think I need to decide on whether to attack the boiler, the motion, or the tender frame. Maybe given the conversations around boilers, the former makes more sense!
|
|
Geoff
Hi-poster
Posts: 171
|
Post by Geoff on Feb 26, 2022 8:24:07 GMT
I need to think about boilers, given the wait times if I go commercial. From the get-go I wanted to build my own boiler, and to hand I already have the flues, steel formers for the firebox and firebox-wrapper, and a pre-flanged smokebox tube-plate. While I already have a Sievert propane torch and an embryonic hearth, I also have basically no experience with any meaningful silver brazing at all at this stage. I make the rough cost to be about £400 for the balance of materials plus consumables. Now, it would appear that in the time Curly was writing the M.E. series there was an expectation this work would be undertaken as part of the locomotive build, but it seems that most people these days outsource this to dedicated boilersmiths either by association or commercially. Why is this? Clearly, I'm starting at the bottom of the skill tree and I have all the enthusiasm but none of the required experience. So, despite a desire to do it all myself - I wonder that it may be a better bet to pay for a commercial one and focus my efforts where my meagre experience is starting to pay off. To that end I have enquired from Western Steam and Southern Boiler Works. I would love to hear any advice on the pros/cons/etc. that the more experienced may have to offer on this as it's a decision I'll have to make soon(ish)
EDIT: Just got quoted the thick end of £4k inc. vat for a boiler so let's just say I'm hoping that 'it'll be fine just take your time and do it yourself' is a reasonable option...
My first Loco build was a Maid of Kent, and I built my own boiler. I did however, have some help from experienced members with the brazed joints. I borrowed an oxy-propane torch which really made it a lot easier with SWAMBO on the other gas torch. There's not many things you can do to a boiler that can't be fixed if you make a mistake. I watched Julian's excellent posts for his Terrier build numerous times before I started. Regarding the valve gear, I did it twice. Once to the LBSC design, which really didn't look too good on the simulator, but may have worked after a fashion and, after reading comments on this forum about lifting links being attached to the bottom of expansion links, once to Don Young's design which I was a lot happier with. The biggest headache I've had has been the fitting of the slide bars ..... and this is where my inexperience really showed. Everything had to go in and come out numerous time whilst trying to fettle the crossheads and slides and it drove me mad getting the screws to the motion plate lugs in and out. I'm getting all twitchy just thinking about it again! Don't be put off building your own boiler, and take a look at Julians posts! Cheers Geoff
|
|
|
Post by William A on Feb 26, 2022 16:17:35 GMT
Thank you Geoff - I'm going to give it a bash I think, there's not much that can go horrifically wrong and probably worth wasting the cash even if it doesn't work out perfectly as a learning experience.
In an related note I'm making a prototype axlebox to test my methods. I have the box sliced down and need to square off the top and bottom. Once that's done, I need to make it into a U shape by removing approx 1x1x1 section from the top-middale of it.
Rather than taking a lot of passes (36 at 50 thou per pass) with my Centec milling machine, is it possible to chain drill out across the bottom of the section and thenuse a slitting saw in the arbor (or a hacksaw) to cut the sides? I would assume yes if this were aluminium, steel or brass and slightly thinner, but not sure if this is possible without cracking the whole piece in CI.
On the note for the miller - I'm finding a bit of trouble - either my horizontal cutters are gouging on the corners (how? why?) or they are eccentric enough that only a couple of teeth are contacting for each revolution. That's what's limiting my depth of cut at the moment. All the cutters appear to be NOS and in fairly good condition - do I need to stone those with gouges? Is there anything at all that can be done with those which are mildly eccentric?
Cheers!
|
|
millman
Part of the e-furniture
Posts: 297
|
Post by millman on Feb 26, 2022 19:33:35 GMT
Never yet found a horizontal cutter that runs true, and that’s after 50+ years in industry. Possible causes are slightly bent arbor, wear on wheel when cutter being ground, try taking deeper cuts and feeding a bit quicker. For the eccentricity try rotating the cutter on the arbor and see if that improves matters, the eccentricity of the cutter may cancel out a slight bend in the arbor. Try clocking the arbor and see if it runs dead true or not, if it is dead true you will have to live with the slight eccentricity that horizontal cutters have.
|
|
|
Post by William A on Feb 27, 2022 9:06:58 GMT
A bit more messing around, this time with filing guides/buttons: Millman, I figure the gouges can't be from the arbor itelf if only about a third of the cutters suffer from it - but the eccentricity I understand your explanation perfectly. There are some cutters which neither gouge nor are eccentric; but are the wrong width or profile - so it must just be the luck of the draw? Regardless, I'll check the arbor later today, thanks for that tip. With regard to feeds, with a 4" diameter, 16 tooth cutter on CI I understand I should be running at about 90rpm feeding at about 12ipm (or two revolutions of a 100 thou handwheel per second) . If only four of those teeth are doing any work though, the cut should be fed at about 4ipm. That kind of feed cutting at a depth of 50 thou over 1/8" and 1/4" off six faces of four axleboxes just for the outside faces is a bit hard to stomach. Am I missing something obvious? Either way, loving messing around on the horizontal mode
|
|
|
Post by ettingtonliam on Feb 27, 2022 9:25:48 GMT
Don't fret about theoretical cutting speeds and feeds. Just feed at a rate that 'feels' comfortable.
|
|
|
Post by Roger on Feb 27, 2022 9:40:41 GMT
Thank you Geoff - I'm going to give it a bash I think, there's not much that can go horrifically wrong and probably worth wasting the cash even if it doesn't work out perfectly as a learning experience. In an related note I'm making a prototype axlebox to test my methods. I have the box sliced down and need to square off the top and bottom. Once that's done, I need to make it into a U shape by removing approx 1x1x1 section from the top-middale of it. Rather than taking a lot of passes (36 at 50 thou per pass) with my Centec milling machine, is it possible to chain drill out across the bottom of the section and thenuse a slitting saw in the arbor (or a hacksaw) to cut the sides? I would assume yes if this were aluminium, steel or brass and slightly thinner, but not sure if this is possible without cracking the whole piece in CI. On the note for the miller - I'm finding a bit of trouble - either my horizontal cutters are gouging on the corners (how? why?) or they are eccentric enough that only a couple of teeth are contacting for each revolution. That's what's limiting my depth of cut at the moment. All the cutters appear to be NOS and in fairly good condition - do I need to stone those with gouges? Is there anything at all that can be done with those which are mildly eccentric? Cheers! Personally, I wouldn't use slitting saws to remove material, they wander given half a chance, and can grab too. i'd just use a hacksaw or mill off the material. I'm not sure what you mean by 'gouges' on the corners. All tools have runout, you just don't notice it that much until you use a long End Mill or a Slitting Saw. i wouldn't worry about it, just be aware of the issue when you're trying to machine a long vertical face. Horn faces can be troublesome to machine because of runout and also wear on the end of the cutter. This is why you'll find that the axlebox binds when it's pushed fully home, because the End Mill is smaller in diameter where it's worn. If you can use one cutter to rough it out, and a new one to finish it, that would help. You'll notice that CNC machines generally use tipped milling cutters, even for milling tall vertical edges. The vertical edges are machined in multiple passes at different depths so that runout and tip wear are the same for the whole surface.
|
|
|
Post by William A on Feb 27, 2022 12:05:59 GMT
Scoring along one side of the cut width may be more accurate of a description than gouging?
Re: slitting - no problems. Is that suggestion with chain drilling and cold chiselling? I’m not out much more than time if I break it, but if milling is a better shot I may as well do that instead!
|
|
uuu
Elder Statesman
your message here...
Posts: 2,815
|
Post by uuu on Feb 27, 2022 15:08:58 GMT
Two revs of a milling handwheel per second feels like a rapid traverse to me (although I know some Centecs have a lever for rapids). I'd try a quarter of that - one rev per two seconds. And then - as noted - if it "feels" right, it is right.
Wilf
|
|
|
Post by William A on Feb 28, 2022 10:22:31 GMT
I've got my prototype axlebox body done: There was ALOT of swarf and many, many traverses - 42 for the keep slot alone! Unfortunately despite the tool being a side and end cutter, the sides of the slot were tapered by about 5 thou on each face. To remediate this one I'll need to either file or endmill the slot square.
As I want to use the horizontal mode, I think I'm going to have to revert back to hacksawing, vertical milling and drilling.
|
|
|
Post by ettingtonliam on Feb 28, 2022 12:08:25 GMT
You are using the rapid (capstan wheel) feed aren't you, not endlessly twidlling the handwheel?
|
|
|
Post by William A on Mar 1, 2022 15:09:30 GMT
Er... that would have been simpler wouldn't it?
|
|
|
Post by ettingtonliam on Mar 1, 2022 21:19:21 GMT
Years ago when I had a Centec, I had a lot (about 600) of 16 DP gear teeth to cut, and I reckoned that using the capstan handle saved me about 30 seconds per tooth, mainly on the speed of the back pass. Doesn't sound a lot, but thats 300 minutes or 5 hours of time.
|
|
dscott
Elder Statesman
Posts: 2,438
|
Post by dscott on Mar 3, 2022 6:51:44 GMT
Western Steam for a QUICK Boiler kit. I ordered a pair of kits for Class 2 and was very supprised at them being ready so soon. It turned out that Geoff was also wanting a boiler so Helen did a batch of 3. Usefully my old Boss now lives a few doors away and comes over to visit his Sister in Reading.
They come with a final heat up and check plus ready done tapered barrels.
David and Lily.
|
|
|
Post by William A on Mar 7, 2022 10:54:02 GMT
Righto, a bit of a cavalcade of shame over the last few days.
I wanted to swap the horizontal cutter after stoning the blades and corners of another to see if I could get a better finish, and it looks like the locking nut has fully jammed on my horizontal arbor and I can no longer remove it, even with the arbor removed and held by the flats in a vice. I've tried WD-40 and heating the nut up and no joy at all. Any ideas?
The recess for the axlebox keep was very slightly tapered from top to bottom - whether that was the table sagging or the arbor bending or just that the horizontal cutter or something else I don't know.
I swapped out to the vertical head and found some other annoying problems. Even when taking very small cuts I'm getting a 'stepping' effect, i.e. if I traverse a spiral on the surface of a piece, by the time I get around to the first corner again the cutter (and spindle) have been pushed upwards. I can't lock the spindle any harder than I am doing, I've tried to dial out the backlash in the fine adjustment wheel and lock that also with mixed success.
I've also noticed that I'm missing three (!!!) gib screws for the Centec's table - two on the X and one on the Y - which is no doubt contributing to the X/Y springing that appears to occur whenever the table isn't locked solid in a given axis. I believe these should be 2BA?
Anyway, enough of the moaning - this is the prototype axlebox and keep. Now to mill the recesses after I've got some punches to match the keep to the box, and the box to the chassis.
Not pictured is the massive amount of swarf generated to get this far...
|
|
|
Post by ettingtonliam on Mar 7, 2022 13:46:35 GMT
Not being rude, but you are turning the locknut the right way? Some are left hand thread.
Yes, I seem to recall that the gib ajustment screws on a Centec are 2 BA. They probably aren't available as dog point any more, but its easy to machine the ends to form a dog point.Don't forget the locknuts as well
|
|
|
Post by William A on Mar 8, 2022 11:46:56 GMT
Not taking it as rudeness at all - this locknut is indeed left-hand threaded but it's as stuck as it's ever going to be in both directions. I might need to get a cheater bar or something at this rate, or just commit to never using the mill in horizontal mode again For the gib screws I've sourced some 1" grub screws for the X-axis, though for the Y-axis I'll need to slot some steel threaded rod; I can't find any grub screws or bolts long enough. Hopefully this should help the rigidity. I'v realised that I should probably not have bothered getting the height or thickness of the keep perfect until it's pinned into the recess; since I can square it up in the mill afterwards. I will need some good audiobooks to keep me going through machining the other six. I'm trying not to think too hard about the tender...
|
|
|
Post by Roger on Mar 8, 2022 12:58:31 GMT
You might be able to get the nut off with an impact wrench. If you've got a socket that fits and a vice you can take to your local garage, they might oblige with their Air Impact gun they use to remove wheels. The probably will have a vice though. Alternatively, if you can't apply enough brute force, a quick run around the nut with an Oxy-Acetylene torch will definitely loosen it. Just get the spanner on when it's still Red hot.
|
|
|
Post by cplmickey on Mar 10, 2022 14:59:07 GMT
You might be able to get the nut off with an impact wrench. If you've got a socket that fits and a vice you can take to your local garage, they might oblige with their Air Impact gun they use to remove wheels. The probably will have a vice though. Alternatively, if you can't apply enough brute force, a quick run around the nut with an Oxy-Acetylene torch will definitely loosen it. Just get the spanner on when it's still Red hot. And whack the spanner with a mallet to try to shock it off.
|
|
|
Post by William A on Mar 12, 2022 19:38:32 GMT
I've replaced the Y-axis gib screws and some of the X-axis ones - but the final one is eluding me - it looks like the allen head has partially snapped off. Any ideas on how to get this out? There's no purchase for pliers, and because of the concave nature of the end that's left, I can't easily get a punch in there to force it around...
I'm going to try with a left handed drill bit...
Along those lines, I'm having a bit of a mare with the v/h on my Centec. It's a Mk.3 head and so has both a quill and fine feed. I still seem to be getting some weird behaviour - as I walk around a part (conventional milling) by the time I get to the middle, the cutter has been pushed upwards by a few thou - so the surface looks like an aztec pyramid.
I managed to get it slightly better by the following actions: - Engage the fine feed lock
- Push the quill UP to take up all the backlash in the fine feed screw
- Engage the quill lock
However this is not completely successful, though much improved.
With the quill locked but fine feed unlocked - I can raise and lower the spindle with one finger on the quill handle - which feels like it's wrong. I've taken the quill lock out and nothing seems awry - it just simply doesn't clamp very well at all?
Am I missing something obvious here?
|
|