letterspider Posted May 25, 2013 Share Posted May 25, 2013 I am starting this page up to record my first efforts at laser cutting in OO gauge. My aim is to produce a detailed, affordable structure by etching onto plywood, learn a few tricks and maybe extend the techniques to other areas of railway modelling. I am happy to exchange ideas with other modellers! Due to the limitations of time I have available to dedicate to this project I am keeping everything as simple as possible. I also apologise in advance if you read my posts, I take a LOT of time on my modelling projects and never finish any of them! First of all the design is the simplest type of viaduct which I have been able to visit and gather photographs for. I am aiming to model an urban scence with under the arch lettings - like this: I am using a simple software called 2D design. I made a test etch on 3mm ply and I couldn't help trying out a few detailing techniques while I was at it. I'm not thinking about how I am going to paint the etches just yet, only concerned with the capabilities of the laser cutter and software I have access to The first results encouraged me to have a go at a simple viaduct. Here is a screen shot - the first etch will be in a weeks time when I go back to work. Link to post Share on other sites More sharing options...
Orinoco Posted May 25, 2013 Share Posted May 25, 2013 Looks really interesting. Please do let us know how you get on Link to post Share on other sites More sharing options...
davknigh Posted May 25, 2013 Share Posted May 25, 2013 You might find this thread interesting http://www.scalefour.org/forum/viewtopic.php?f=14&t=2683 Cheers, David Link to post Share on other sites More sharing options...
letterspider Posted May 26, 2013 Author Share Posted May 26, 2013 A bit of fun, my own version of the Sweet Toof horse trailer. Test etch of brickwork on 3mm ply, with a try out of graffiti using pens. Link to post Share on other sites More sharing options...
raymw Posted May 28, 2013 Share Posted May 28, 2013 Hi Letterspider, What is the approximate size of the arch, and how long does it take to produce it by laser cutting? Best wishes, Ray Link to post Share on other sites More sharing options...
letterspider Posted May 29, 2013 Author Share Posted May 29, 2013 Hi Letterspider, What is the approximate size of the arch, and how long does it take to produce it by laser cutting? Best wishes, Ray I have decided to make something generic - it is intended to be high enough under the arch to allow single track with catenary to pass under it, so the whole is about 10cm from base to the top. If this simple design works okay, I might try variations. The design takes as long as you want it to take, it becomes a labour of love to pick out errors caused by shortcuts in the copying and pasting of the brickwork. I think I have spent 5 hours on it so far. The actual etching of the double arch I haven't done yet but I estimate about 1 hour because with my software the laser etches the lines in the order in which you drew them, so you can imagine there is a lot of to and fro-ing of the laser head across the plywood. I am sure with more sophisticated software the design and etching can be sped up considerably. Link to post Share on other sites More sharing options...
Etched Pixels Posted May 29, 2013 Share Posted May 29, 2013 What file formats does your software use - there are bits of software around that can do things like re-sort the drawing order of some types of vector files. An optimum cut order is a very hard problem but a good cut order is not too difficult. Link to post Share on other sites More sharing options...
letterspider Posted May 29, 2013 Author Share Posted May 29, 2013 What file formats does your software use - there are bits of software around that can do things like re-sort the drawing order of some types of vector files. An optimum cut order is a very hard problem but a good cut order is not too difficult. I can export as .emf files and have played around with Adobe Illustrator at work but for some reason this software won't run properly on Windows XP pro 64 and so I have soldiered on with the 2D design software, as the biggest problem is getting access to the laser cutter! Link to post Share on other sites More sharing options...
letterspider Posted June 6, 2013 Author Share Posted June 6, 2013 So I have done a test etch of the viaduct using a scrap of laser ply. Unfortunately it was a bit warped, resulting in badly frazzled ends due to the laser being off focus. Ply is also not a very consistent material, as the inner ply may have knots and areas of adhesive filled voids, all of which cause errors if the laser cuts through them. The middle areas do look very good, will spray them up in a colour close to mortar and attempt to dry brush brick colour on. I have made the arches to a scale 40 feet wide and they are too wide for the purpose I intend (urban viaduct). So back to the drawing board to make scale 20 to 25 foot wide arches and try out on 3mm MDF. Link to post Share on other sites More sharing options...
Beatty 139 Posted June 7, 2013 Share Posted June 7, 2013 Ply is no friend of the laser from experiences it takes very little to cause an issue I am trying at the moment to source thin section ply with interior glue that should perform like laser ply (which from memory isn't available under 4mm) I am trying to source 0.6mm 0.8mm 1mm & 1.6mm its possible that 0.4mm could be possible as well but would be painfully expensive. If we can get it, I would hope that it will solve some of the 'dirty' cutting and other issues with normal aircraft ply. Link to post Share on other sites More sharing options...
letterspider Posted June 8, 2013 Author Share Posted June 8, 2013 You didn't mention Balsa at all - is it not available in thin sections / not possible to laser cut? Ply is no friend of the laser from experiences it takes very little to cause an issue I am trying at the moment to source thin section ply with interior glue that should perform like laser ply (which from memory isn't available under 4mm) I am trying to source 0.6mm 0.8mm 1mm & 1.6mm its possible that 0.4mm could be possible as well but would be painfully expensive. If we can get it, I would hope that it will solve some of the 'dirty' cutting and other issues with normal aircraft ply. Link to post Share on other sites More sharing options...
letterspider Posted June 9, 2013 Author Share Posted June 9, 2013 Second protoype being designed with smaller 20 foot diameter arches and the correct brick pattern (English bond). Screen shot of the work so far. I will hopefully be etching this onto MDF for the reasons already mentioned. Another problem is that the laser appears to anneal the ply when it etches. This makes the mortar joints repel all water based paints and enamel sprays also seem unable to penetrate. As long as I am modelling weathered brick work (which I am) this should be okay. The mortar in blue engineering brick seems to be black most of them anyway! Link to post Share on other sites More sharing options...
letterspider Posted June 11, 2013 Author Share Posted June 11, 2013 I will be posting two pictures of the latest work on the viaduct. Comparing the ply and the MDF, the MDF has proven to have better results. I was able to cut staggered 1mm brickwork onto the ends of the viaducts whereas the ply simply turned to ash. Even so I am having a lot of trouble getting the staggered ends right and I'm not sure they are worth the trouble, as they are rather fragile. I thought I'd have a go at cutting some under arch details. I think the wooden doors look quite good but I think next time I should have etched a breeze block wall. I have also cut some acrylic to fit under these arches - to model a swanky gastropub or maybe a used car salesman (like this one I drove past yesterday) The viaduct I have so far been modelling is similar to the arches under Brixton station, where the arc is a complete semi-circle with the lining bricks forming a complete circumference (like this) However this seems to be quite rare and I have made adjustments to form viaduct arcs resting on brick piers. My piers are quite wide as I will probably be sticking these viaducts onto foam blocks, rather than wood. I have used wood before and everything starts to get horribly heavy. Link to post Share on other sites More sharing options...
Wild Boar Fell Posted June 11, 2013 Share Posted June 11, 2013 Hello, Just thought it might be worth me advising that I have heard that cutting a lot of MDF can clog up the laser cutters pretty quickly so you might have to watch out to avoid problems. I cannot say I have experienced the same problems with ply turning to ash as the Terraces and MPD on my layout are made out of it. Hope this helps, Wild Boar Fell Link to post Share on other sites More sharing options...
Gt.Shefford Posted June 12, 2013 Share Posted June 12, 2013 Hello, Just thought it might be worth me advising that I have heard that cutting a lot of MDF can clog up the laser cutters pretty quickly so you might have to watch out to avoid problems. Could you elaborate on this statement as I have never heard of medite causing any problems. Had our machine over 4 years, cutting mostly medite and appart from regular cleaning of the optics never had a problem. Have recently started cutting 0.8 and 1.5 WPB Finnish birch ply. To date we have processed over 40 4'x4' sheets of the stuff. Great material to work with, cuts really well with a small amount of edge burning. Jonathan Link to post Share on other sites More sharing options...
Wild Boar Fell Posted June 12, 2013 Share Posted June 12, 2013 Hello Jonathon, Without giving too much business information away, the laser cut kit supplier that I do part time work for had experienced far faster clogging of a machine when using 3mm MDF as opposed to the usual choice of plywood. The MDF soot had clogged some of the mechanical components leading to the cutter losing its registration, this happened over a very short timeframe and was not experienced with ply. The main reason I commented was the object being cut was fairly similar to what letterspider is doing as it had alot of small brickwork. I accept this may be a one off and may depend on wood supplier and type of laser cutter and extractor system. Hope this helps, Regards, Wild Boar Fell Link to post Share on other sites More sharing options...
Gt.Shefford Posted June 12, 2013 Share Posted June 12, 2013 Thanks Wild Boar Fell, just curious thats all. I've only cut 3mm once, and from memory it did generate more smoke than our 2mm - IIRC that was what propmted us to replace the supplied extractor. Jonathan Link to post Share on other sites More sharing options...
Beatty 139 Posted June 23, 2013 Share Posted June 23, 2013 Presuming that on the whole were all sourcing our ply from similar sources, I have been seriously considering ordering a run to be done in interior glue as I have been finding that 0.4mm up to 1.6mm cuts fine on the whole but in areas, exaggerated on the 0.4mm (which is a right pain) it will come across a area in the ply which causes flaring, localised superficial scorching to the surface adjacent to the surface and poor cut. I have put this down to the action of the resin glue, but have others found the same issues? Is there a way over it to save the expense of a special order, I have tried increasing the amount of air assist air flow but not dramatically. I used to have a supply of interior ply in 1.6mm but stocks are getting low and I could do with making my mind up what approach next, Its annoying that from what I can see the ply manufactures do not realise there is a substantial if limited market for laser ply below 4mm thick. As for MDF my personal experience is that it is does create more mess than ply and I have just compensated for this with increased cleaning and servicing when doing a run with it, I have not found that it has ever created a mechanical issue as yet. Link to post Share on other sites More sharing options...
letterspider Posted June 23, 2013 Author Share Posted June 23, 2013 Work on the 4mm MDF has been very good last week. I have now cut and etched enough panels to make a 6 foot viaduct. It is a matter of trial and error on each and every piece of MDF to find the correct power and speed for the cutting and etching, although on the whole the MDF is a lot more consistent than the ply and being denser I expect can be used to support the structure with little bracing. Taking inspiration from the car salesman under the viaduct, I have been using the arch templates for cutting internal structures. So far I have cut and etch clear perspex for glass and variations with arches filled in with brick or breeze blocks, some of which can be seen in the pictures below. The perspex needs to be etched where the window and door frames are to be painted in, this keys the surface for acrylic paint. Once dried I carefully scrape the excess off with the edge of a thick piece of plastic to leave the outline. The folding doors are glued together using Humbrol Clearfix. The next problem - how to build refuges on to the viaduct - as the trackbed is only going to be 10cm wide. Link to post Share on other sites More sharing options...
letterspider Posted June 23, 2013 Author Share Posted June 23, 2013 Further to comments about MDF fouling up the laser cutter - it certainly does produce a nasty brown resin as it is cut. We usually place a thin piece of solid scrap under any MDF that is being cut, this prevents this resin building up on the honeycombed support grid underneath (which I am told costs about £500 to replace). This resin build up is a nuisance as it can stain the next project you are working on - such as perspex. Link to post Share on other sites More sharing options...
Beatty 139 Posted June 23, 2013 Share Posted June 23, 2013 If someone does let the MDF residue build up it will clean off well with paint stripper, but I would recommend just wiping down in IMS or Meths at the end of the day. As an alternative for the honeycomb you can cheaply source the 10mm square grid material used by the ventilation grill manufactures if you ever do have an issue. Link to post Share on other sites More sharing options...
letterspider Posted August 4, 2014 Author Share Posted August 4, 2014 If someone does let the MDF residue build up it will clean off well with paint stripper, but I would recommend just wiping down in IMS or Meths at the end of the day. As an alternative for the honeycomb you can cheaply source the 10mm square grid material used by the ventilation grill manufactures if you ever do have an issue. Can you give me the contact details of a grill manufacturer - as we do now need a new grill. Link to post Share on other sites More sharing options...
letterspider Posted August 4, 2014 Author Share Posted August 4, 2014 Sorry to everyone who was expecting to see this viaduct assembled. As always this is another project on hold - in this case until a new kitchen worktop is put in and the loft is fully insulated. Our laser cutter is also out of service - apparently a problem with the focusing which needs to be fixed. Link to post Share on other sites More sharing options...
Beatty 139 Posted August 13, 2014 Share Posted August 13, 2014 If you contact a ventilation suppy distributor, not quite sure where you are but there are plenty around, e.g. VGC in Dudley they should be able to suppy what will be described as Egg Crate Core in Mill finish this is the you don't want it as a extract grill only the core they normally have thus avalible to drop into suspended ceilings to provide a return air path. Hope that helps Andy Link to post Share on other sites More sharing options...
BrushType4 Posted October 10, 2014 Share Posted October 10, 2014 Hi LS, Had a chance for any more progress? Link to post Share on other sites More sharing options...
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