flubrush

The milling machine is a Seig KX1 with Mach3 controlling it. The brass I use starts off as clock plate - CZ120 grade. I prefer to use sheet as I can hold the part more easily on the mill and can machine the whole part, just leaving small tabs to keep it in the sheet which then have to be cut through to release the part. The tyres are machined from free cutting steel blanks which I obtained from the SSMRS parts table at a meeting a year or two ago. John Holden, the parts officer at the time, had got a box full of them from someone in the past and I literally bit his hand off to acquire them - saves all the hassle of boring and parting off from solid bar. Jim. Jim.

Well my Caledonian dock tank wheels have been completed - brass CNC milled centres and steel tyres turned, fitted and profiled on the Cowells. I've also milled some wheels for a Caledonian 0-4-0 pug using the same methods. Jim.

Here's a sample of the DXF output list from my slightly ancient copy of CorelDraw. Plenty to choose from. :-) Jim.

Jason, Just a comment in passing, but there can be quite significant differences in DXF file features depending on the version. I note from the header of the DXF file which you attached that it is a 2014 version file - probably the latest version. AutoDesk are quite good at making significant changes with every new version of AutoCAD and it is difficult for other applications to keep up with the changes. So you can get some applications not importing DXF files properly if they expect an earlier version of the file. A lot of applications which export DXF - including AutoCAD itself - give the option of outputing several earlier versions of the file and it is generally accepted that the R12 version of DXF seems to be accepted by every application. (This is the pre-year 2000 version!!!) So it might be worth exporting DXF files in an earlier version if possible to see if the problems are solved. Jim.

Mike, Where did you measure the 0.6mm thickness? Did you just measure in one place? I use styrene sheet in my CNC milling machine and the one thing I have found is that sheet thickness is nominal and can vary by quite a margin around a sheet. To get accurate thickness for my purposes, I start with a thicker sheet and surface mill it down to the thickness I require to get an even thickness overall. So your 0.6mm sheet might have been more than 0.6mm in places. :-) Jim.

I don't actually think it is an error. The graphics applications are actually stretching a shape and curved corners should deform in that way if the stretch algorithm is applied properly. If you stretch a rounded corner rectangle in a CAD program, then curved corners are maintained at the same size and curvature. Jim.

I spent and hour and a half last night just drawing regisration marks on that MK5 file to try and work out whats wrong with the registration. So far nothing found! Tonight I'm going to investigate the droplight and bolection layers as these seem the two worst.... Andy G Andy, You might have to watch out for the styrene sheet stretching under the cutting action of the blade. This is a known problem when cutting the panelling layer out by hand. David Jenkinson shows his method of getting round the problem in his book and I do remember a demonstrator at the London Easter show way back in the 60s advising builders to cut the panelling layers first then cut the main sides to match the size of the panelling. :-) You could check that just by putting a ruler on the panelling layers after cutting to see if there is any stretch. Jim.

I wonder if you might be underestimating the strength of your bridge. If all your plastic joints are well made then you might find that the deflection of the bridge under load on its own is less than that of the seven foot brass girders. Jim.

I've just done a trial cut of all my CNC code in Plastikard. The basic GCode is generated in Cut2D - that's the wheel, balance weight, boss and spoke shapes. I've then hand written the GCode to cut the flares on the spoke inner and outer ends. First the wheel centre still in place after cutting in sheet Then the wheel removed from the sheet and cleaned up a bit, showing that everything seems to be cutting OK and there are no obvious faults. The one thing I do note is that the 0.4mm cutter which is used to cut the gap between the boss and the balance weight is cutting into the flare round the boss. I let it run all round the boss thinking it would be OK, but it looks as though I will have to work out another way of doing it to avoid this. The boss and counterweight are sitting proud by 0.2mm. I tend to do this so that any marks on the side of the boss when shaping spokes will be removed when turning off the 0.2mm when the work on the spokes is finished. Now to cut it in brass but I might have to order up some 3mm brass sheet to do it, so might be a day or two till that happens. Jim.

David, Just found some more pictures by rooting around on the Bluebell site a bit more. http://www.bluebell-railway.co.uk/bluebell/locos/178_wk/178_wheels_derekh_13dec09.jpg http://www.bluebell-railway.co.uk/bluebell/locos/178_wk/178_frames_derekh_13dec09.jpg http://www.bluebell-railway.co.uk/bluebell/locos/178_wk/wheels_robf_8nov09h.jpg http://www.bluebell-railway.co.uk/bluebell/locos/178_wk/robf487_11oct09h.jpg Also dug up this Derek Hayward selection which has got a lot of wheel pictures running through it. http://www.derekhayward.co.uk/BluebellRailway-1/Locomotives/323-Overhaul/21095817_DQkpVp/1677931419_zrxrnk7#!p=1&n=10 There's also another photographer mentioned - a Ron Faulkener - but his pictures appear to have been stored on Fotopic and I can't find if he has uploaded them to anywhere else. Jim.

David, I hope they help. I'm just hand writing GCode for my Caledonian 498 class wheels at the moment and I'm hoping I might start cutting some trial wheels tomorrow - in styrene in case I've made any mess-ups with the code and the small cutters might survive any non-intended excursions. :-) If all looks well, I'll start cutting brass. Jim.

Just found these pictures on the Bluebell site - in case you haven't dug them up yourself. http://www.bluebell-railway.co.uk/bluebell/loco_news/12/27_removed_buffer_beam.jpg http://www.bluebell-railway.co.uk/bluebell/pic2/wn-2010/323frames_derekh23may10.jpg http://www.bluebell-railway.co.uk/bluebell/pic2/wn-2010/323_wheels_derekh_8may10.jpg http://www.bluebell-railway.co.uk/bluebell/loco_news/09/323_wheels_derekh_23oct09.jpg http://www.bluebell-railway.co.uk/bluebell/pic2/wn-2009/323_andrews6882_3sep09h.jpg Pictures of wheels during rebuilds are usually the best since you don't get them hidden behind/under bodywork. Jim.

David, They could well be. I remember seeing a note on a drawing of a casting which I have which said "round off corners to X inches radius". I had a look for it again yesterday, but couldn't find it again. :-) But it did look as though the drawing office had left the cosmetic points of the casting master to the pattern makers, which could have led to rounded ends to rectangular spoke cross sections. Jim.

David, It might be worth looking for someone on the Bluebell Railway to see if they can give you some help - maybe the owner(s) of the P class tank. Jim.

David, Maybe more of a fillet between the front of the spokes and the boss if you can manage - as is apparent on this picture http://www.derekhayward.co.uk/BluebellRailway-1/Locomotives/27/19947660_f45cTG#!i=1676125356&k=4xBF2Sr&lb=1&s=A And I know what you mean about finding your way around 3D CAD . :-) I reckon a lot of people are thinking that 3D printing is going to make life a lot easier for modellers, that is until they realise that they will have to get their brains around 3D CAD work, and that might be the major stumbling block. :-) Jim.

Ahem. February 2013 Gazette - page 12. Jim.

David, You should be fairly safe with the mass of the Boxpok wheel - and it might not be too bad with the Class P since it has very small drivers with short spokes which will probably be a lot sturdier than a larger diameter wheel. UK S scale modellers seem to prefer the split frame method of pickup and it might be worth looking at the possibility of conductive centres (even metal?) to allow your wheels to be used easily for that purpose. On the availability of wheels in S, the situation in the UK actually wasn't too bad some years ago when the Mike Sharman range of 4mm scale wheels was available. He had such an extensive range that you were pretty sure of finding a 4mm scale wheel which was the correct diameter in S scale in the small to medium sizes, with the correct number of spokes and, possibly, the correct crank throw. I built a Midland 1F tank and the wheels were one of Sharman's 4mm scale ones and they are pretty well spot on in S. Unfortunately, the Sharman range went off the market some years ago when the person who took the range over from Mike Sharman couldn't maintain production. I look forward to seeing your results. I won't be starting my own wheel making for a week or two - I'm in the middle of hacking CNC holes in some JLTRT 7mm scale resin coach sides for a friend and that's taking a fair bit of time and effort at the moment. :-) Jim.

Scott, I read somewhere recently that someone in, I think, Australia had printed a gun but it failed when fired. I suspect that there are variations in the strengths of the plastic you can use which would make a successful gun a bit of a lottery. Getting a bit off topic now. Jim. PS - Another off topic - anyone got success in using smilies on this version of the software. Apart from having to choose from a huge list which can take a long time, the smilie eventually displayed is not the one that was chosen.

I could generate Gcode to do the rounding of the spoke edges but it might be easier to do it by hand. I think it will still need a fair bit of experimentation until I get the result I want. You want to join the society. We have several members from countries other than the UK. The problem the society has in providing parts is in trying to cater for the wide range of interests of its members. A survey carried out a year or two ago showed that the interests of society members covered a very large number of the UK railway companies, as well as Irish, European, North American, African, New Zealand, Australian and Malaysian prototypes. With a membership of around the 110 mark, this means that the numbers interested in particular items can be quite low and it is difficult to raise enough interest to make the production of a part or a kit an economic possibility. The society attempts to provide a generic range of parts which can be used or modified by a wide range of the members, but S scale modellers should be prepared to have to scratchbuild a lot of their modelling. Have you thought about using the 3D process for producing a master to use in lost wax casting? This would possibly provide a solution to durability and might be cheaper than 3D printing all your wheel centres if you require a large number of wheels. but you would need a lathe to finish off the brass centres. I've got several other projects on the go at the moment, but i hope to get back to coding forf the wheels someting in June. Jim.

David, I'm coming into this thread a bit late - I missed the start in March. But you may be interested in the fact that the S scale society in the UK provides ready turned tyres - probably a bit cheaper than your specially made ones. There is one of 5' 7" diameter which would be close to your requirements - about half way down this web page http://www.s-scale.org.uk/wheels.htm Also for axles, 0.125" or 3mm silver steel will do very well. It comes straight and round and accurate to size from metal suppliers and only needs to be cut to length. With plastic centres, a solid axle is all that is required. Also you might want to be prepared to finish turn the completed wheel true if the 3D printed centre is not completely concentric. I'm making my own S scale wheels at the moment, but cutting them out of brass with a CNC mill. Here's a picture of an early experiment. The centre is for a four foot diameter wheel for a Caledonian 498 class 0-6-0 dock shunter. I've now got access to the original drawing for the locomotive wheels, so I'm now re-doing the code for the wheel cutting. My original code was based on trying to assess the spoke shapes from pictures which usually entails a lot of guesswork. I use split axle pickup so solid metal wheels are ideal for this. I look forward to seeing how your project progresses. Jim.

And it's also worth considering installing a wooden floor if the garage floor is concrete or composite. This provides insulation from the cold concrete, but, more importantly, makes life a bit easier on your feet and legs since you could be doing a lot of standing around when building and running the layout. This can be done fairly easily by laying battens on the existing concrete floor with damp proof protection, then laying tongued and grooved wood or chipboard on the battens. Jim.

Even worse. Jim.

If you type "South African Railway Modelling into Google a few sites pop up and these sites have links pages with even more pointers. There' s UK modelling site with a good links page here http://www.sarmodel.com/ and a South African site with a good links page here http://www.cmd-models.com/links.html and there's a Yahoo mailing list at http://groups.yahoo..../SAR-Modelling/ which has a steady low level of messages. There's also a site with a huge selection of drawings available on CD - about £20 for a CD of a full set of drawings for a particular locomotive. http://www.sarsteam.co.za/ Whatever turns you on. :D Jim.

Ian There are several members in the UK S Scale society who model Cape Gauge such as WAGR and NZR and I've just been having an email exchange with another member who is modelling an SAR Class 25. He has almost finished the 60ft condensing tender and is close to starting on the locomotive itself. If you are going to the St. Albans exhibition this coming weekend, you might see the tender on the S scale stand although I'm not sure on which day he is attending. Unfortunately, native SA modellers don't seem to have taken andvantage of S scale to model their railways accurately and they seem to he happy with H0 outline on H0 track. I assume they can get away with this since the SAR loading gauge was very generous and wider gauge wheels won't look too out of place. Whereas, S scale on H0 track is popular in New Zealand, and some parts of Australia. [PLUG ]Just in case your interested you can join the SSMRS here. http://www.s-scale.org.uk/join.htm [/PLUG ] Jim.

There are a few suppliers of all the bits you need - such as Machine-DRO http://www.machine-dro.co.uk/index.php?target=categories&category_id=3 Jim.