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D869

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Everything posted by D869

  1. 'bout time I put something on here again. I haven't been idle but it would be fair to say that things have rather lacked focus, basically doing what takes my fancy rather than aiming to hit some sort of target like having an O2 running for the DJ Expo. The O2 will still happen though. The last few days are a good example - the Hayle tractor currently has, effectively, 'skid steering'. I want to at least have a try to make the steering work... and consequently redesign the under baseboard drive system... which in turn may have a knock-on effect on the cutouts in the (so far non-exis
  2. First work out the geometry of the flare on a dome. That seems somewhat tricky on its own. I struggled to do it with a file and some brass, never mind telling software how to do it. At the risk of diverging well off the OP's question... I suspect it's do-able - at any point when viewed in cross section it's probably not unlike a circular fillet but the radius is small on top of the boiler and a good deal larger at its lowest point. Not all flares are created equal - some seem to flare so that they end up almost tangential to the boiler cladding, others hardly seem to bother much an
  3. +1 for OpenSCAD (but you knew that already) If you are happy getting your hands dirty with code then it's ideal - most of the tank barrel and rivets below were done with code - like spacing the rivets equally around the barrel and doing the 3d trig required for the rivets on the filler skirt. The top of the filler is a separate bit BTW. It's not all code - the vent and syphon bosses are rotated DXFs as are the domed ends on the barrel. Horses for courses. I also use a lot of 'if' statements to allow me to do an assembly preview model pulling together DXFs f
  4. As a rule it is wise to have a sheet of something under the job. Ply, aluminium, MDF, Tufnol etc. This can be bolted or clamped to the bed without the clamps interfering with the cutting. Double sided tape is very useful for holding the sheet being cut onto this. For metal I use the Diall stuff and use a hair dryer to get it unstuck afterwards. Maybe something less grippy for plastic but I have not done much of that.
  5. I think the best advice is not to worry about the number of flutes and just get on with doing some milling. One day you might need to care but for now you really don't. Whether a cutter can plunge does matter, of course and it's worth buying ones that can do this. Did you also know there are single flute cutters?.... and reasons why they work better for some jobs... but again, to get started with an MF70 it really doesn't matter. Bigger diameter mills snap far less frequently, so use the 2mm and 3mm cutters while you are learning. Make sure you have some spares in hand
  6. The X and Y axes are finished and have done plenty of good work cutting out bits for the O2. @justin1985 the reason I made my own motor mounts was to allow the MF70 to be swapped quickly between manual mode and CNC. It works as intended and I can swap in about 5 minutes. For quick, simple milling jobs I prefer manual mode. Happy to share the details if you are interested. You may need another machine to make the bits though The Z axis is a lower priority and is not done yet. I did do a mockup using an offcut of laminate flooring and bits robbed from the other axes to
  7. Likewise - mine does the job I need. There is a pretty big jump in price and size when you look at alternatives so I have no plans to change it. Incremental improvements, however, are well worth a look.
  8. Not weird at all. Same person doing the asking My standard spindle has about 2.5 thou runout measured on a cutter shank in the (Proxxon) collet. There are other reports online of circa 3 thou runout on the Proxxon spindle. The problem with this is several-fold. Firstly you get a cut that is oversize (3 thou is a fair percentage for a 1mm cutter). This error does manifest itself if using CNC to cut out shapes (and can be compensated by fudging the cutter diameter when generating g code). Secondly there is a high probability that you will only be cutting on one flute instead of the
  9. I'd suggest starting with a rewheeled 'N' loco and saving the full loco kit build until later. Then you will have something up and running quickly with which you can test your track and electrics.
  10. Could you do the black circles with a fine marker pen with the wheels turning in a lathe/drill/loco ?
  11. Good stuff Pix. Glad you are keeping up the work rate. I especially like the DMU nose - always good to see how people tackle tricky design issues and those cab window surrounds coinciding with the angles on the nose definitely come into that category.
  12. I reckon if you shift over to a different L&B then you will keep the RTR folks at bay for a while longer https://www.youtube.com/watch?v=ZjBKQlr9fSs The donkey at 1:12 is *NOT* happy! I do like a tin turtle too Oh... don't mind me... the randomness is quite an accurate reflection of the contents of my real workbench anyway.
  13. Thanks Tim and thanks for the postings about your loco builds which have definitely helped me with the O2. I do like a bit of L&B and am particularly glad that a short stretch has reopened and we can ride in restored coaches and admire the Exmoor scenery. I like my own narrow gauge models in 16mm scale with actual steam though
  14. You have the 16T kit from the Association - plastic body and etched chassis. Personally I'm a fan of this kit and have built several of them in different variations (top doors or not, bottom doors or not, different brake designs etc.). I generally scrape the insides of the sides to taper them a bit so that the top edges look thinner and add some 5 thou plastikard fillets on tops of the corners to complete the corner strengtheners. The slots in the sides are a nice touch. I'm not 100% sure about their later condition but I suspect you should probably delete the tiebars b
  15. Gosh... five! That's a vote of confidence. I hopefully have one on the way with completely wrong bogie centres which will need some stretching. Ian Morgan's post on t'other thread reminded me of another thing... I wonder if we will get to pay extra for import taxes and then service charges on top to for the privilege of having said taxes collected from us. I've had that happen before now with an order from the US but it seems pretty random.
  16. From https://en.wikipedia.org/wiki/British_Rail_Class_121 - 8'6 bogies and 46'6 pivot centres I notice they have some Green Max in stock too. Historically this brand had better answers for 1st gen DMUs. The product numbers seem now to be in the 57xx range and most of the listings dont quote the bogie wheelbase but maybe there is hope for a 17mm or 17.5mm wheelbase bogie one day? ... or maybe they have moved on to making GWR Pannier tanks now?
  17. MinerChris needed to install a replacement Tramfabriek motor in his 122 to get it to run properly. They seem to do quite a trade in them so maybe factor two new motors into your sums
  18. Lovely job Jim. Good to see it is now in revenue earning service. Onwards to the next project now then
  19. Stephen Harris' kits are excellent. As you say they are 2mm scale. That is a 3% size difference from British 'N'. Unless you have an identical vehicle to 2 1/16 mm scale alongside then you are unlikely to notice... and with wagons I suspect you'd be pushed to tell even if you did have two identical ones. The Association shop also does a number of BR era wagons... it just depends how 'modern' is your idea of 'modern'. http://2mm.org.uk/products/shops.php?shop_num=2 You will also need some 2-027 wheels from the shop to go under your kits - these are 'N' profil
  20. Brakes... I knew this was going to be quite an involved job and sure enough it was... and so is this post (sorry!) The O2 brakes are pretty prominent and even the cranks by which they are driven are on full display. MinerChris does have one of Mr Higgs' chassis etches in his gloat box so I could have pinched the brake etches from that but that seemed rather a waste. The Dave Holland keeper plate design complicates matters because the brakes must be removeable if the wheels are also to be removeable. I spent a whole evening just thinking about how to make all
  21. I'm not so sure. My (early) Hymek notes say that the wormwheel is 5.8mm OD and has 20T. This doesnt work out to a whole mod number but maybe that is the 'fudge' to allow it to pivot. The spur train in the bogie works out to mod 0.3 from my measurements - the wormwheel moulding is a compound gear giving reduction between the wormwheel and the spur train.
  22. I'm not sure how you would get the quartering 'in sync' with 3 axle gears. if your axles fit the bearings well and the crankpins fit the rods well then having a gear on just one axle is the usual approach. RTR models with fully geared wheels usually have tons of play around the crankpins which may be an option... but once you open the holes out you can't close them up again so I'd treat this as a last resort. I've usually had to tweak the quartering a little after using the quartering tool. It's still worth using because it presses the wheels into the muffs squarely but
  23. I've never had much success in getting wheels out of muffs non destructively. Most folks think it's better to trash the muff and avoid any risk of damaging the wheel. Sounds like you have a methodical approach. We're probably repeating ourselves but check for machining burrs on the gears (and file them off if you find any) and also make sure that the gears are not catching on anything at some point in their rotation - both of these things will mess up your running in potentially intermittent ways.
  24. There are probably two questions getting mixed up here - one is how to motorise an MU... which may involve cannibalising an RTR thing or creating something to make life easier, perhaps 3d printed as discussed or something etched along the lines of things that have gone before such as Mike Bryant's offering or TPM's kit that cannibalised a US Bachman A/B unit to get two for the price of one(ish). The other question is how to build a custom diesel chassis where the reason for doing so may be the absence of something suitable to cannibalise or a feeling that the RTR option doesn't run
  25. I was having another look at the gear question. My notes of past research say that Farish locos have 0.3 mod gears... which ties in with what Julia said too so if you want to have the option of using the Association drop-in wheels then 0.3 mod seems like the thing to have. My notes also say 0.3 mod for my Dapol Hymek which is one of the early ones so things may have changed. I haven't found anything that beats the prices from the 2mm shop. If I understand correctly the gears are now being done in house. Whether the in house person has the capacity if we all start building diesel bo
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