martin_wynne

I also remember a chaired bullhead track product trialled by Ultrascale. I recall seeing Brian Rogers with some pre-production samples on an Ultrascale exhibition stand. This pre-dated Len Newman's chairs and looked very promising. The actual details are hazy, and I don't think it ever reached the market. Probably Brian was too busy with the wheels and gears to have time for it. At that time the only plastic-based bullhead track available was SMP Scaleway. Next on the scene was Ratio EMTrack. Martin.

p.s. Talking of misinformation, my apologies. I think it may be PVC filler in the Polypipe cement, not ABS as I said. Or maybe both. Martin.

@Haggerleases Hi, Found the original instructions text, apparently written for Exactoscale by Russ Elliott: 'Polypipe' is a commercial solvent gel used by plumbers for welding plastic pipes and tubes. It can be brushed, sparingly, over wooden timbers, and will impregnate the wooden surface, to aid subsequent solvent bonding of plastic components. A wipe of ordinary solvent onto the wood before applying Polypipe, or diluting the Polypipe with normal solvent, will aid the impregnation. Bostik PVC Weld Cement M5417 is an equivalent to Polypipe. I can't find Polypipe in the Digest Sheets, but there is a whole forum topic about it from 2010 which is public (from which the above): https://www.scalefour.org/forum/viewtopic.php?f=5&t=818&p=4787 Including the reported comment from Bernard Weller: "we didn't know where people would be using the product so we had to recommend something that was absolutely 100% going to work". Like many forum topics, it starts off with good info, which then gets muddied with misinformation from others. You want the Polypipe adhesive cement, not the pre-cleaner. cheers, Martin.

@Haggerleases Hi, If possible, it's a good idea to have been around this hobby for 60 years. The Exactoscale company was originally founded by the late Bernard Weller. When he introduced the injection-moulded chairs, he wrote detailed instructions for their use, which included the use of Polypipe on plywood timbers. After his death the Exactoscale company went through several hands, including an arrangement with the previous owner of C&L. The present situation is difficult to fathom. The company still exists and has a web site, but appears not to trade. Its products are available only via the EMGS, Scalefour and S7 societies, to their members only. Where the original Exactoscale instructions have got to in the process, I haven't the faintest idea, but I assumed they would still be available from the present suppliers of Exactoscale products. Exactoscale always had a strong association with the Scalefour Society, and I suspect the Polypipe instructions are still in the Society's Digest Sheets, which are online to their members. I will have a look. If I've got the history wrong, apologies. Memory is fading fast. cheers, Martin.

@Wayne Kinney Hi Wayne, Worth a try, but I'm a bit doubtful. Polypipe is essentially ABS filler dissolved in butanone. It's intended as a gap-filling adhesive for ABS components, which the butanone bonds with. On other materials as the butanone evaporates it would leave behind a plain layer of ABS. On wood grain it penetrates the grain and embeds ABS in the grain, but it's not going to do that on resin-printed components. My guess is that the deposited ABS would rub off. But I don't know without trying it. You don't have to buy Polypipe to do a test -- just dissolve some scrap ABS (or HIPS) in butanone. cheers, Martin.

@Haggerleases Well there's a surprise. Follow the chair manufacturer's instructions, and it works. Martin.

@Haggerleases Hi, The intention is that you use the plastic timbers with plastic chairs. The chairs are not designed or intended for plywood timbers -- that's entirely up to the user. cheers, Martin.

@Penrhos1920 Hi, There is no gauge-widening option in Templot. It is normally done using the track gauges when constructing the track. For the 3D Plug Track, there is a gauge adjustment option on the chairs. You could therefore print a set of chairs for a widened gauge, and substitute them for the ones created with the turnout. However, the above question was not about Templot's chairs, it was about Andy's chair files. Two different things. Normally you would not want gauge-widening for the special crossing chairs, but you might do for the check rail chairs. cheers, Martin.

Sigh. I said "typical" vehicle length. Say anything with 4 wheels. Anyone driving a long vehicle would know that they can't fit between the gate and the track.

And how much simpler and safer would it be if the gate was set back a typical vehicle length from the track? You could then get through and close the first gate, check for a green light on the opposite side, drive across, get through and close the second gate. No walking to and fro, no risk of stopping on the tracks. Martin.

After the 6-bolt fishplate, we expected nothing less. Martin.

@Haggerleases It's a bridge chair. Either L1 (48 lb) or M1 (43 lb) size*. For plain track they are used only on waybeams -- on bridges, ash pits, turntables, etc. : Also used within pointwork where there is no space for a standard chair. The L1 is too wide to fit on a standard 10" sleeper. The M1 just fits, but the screw fixings would be too close to the edge. p.s. DCC Concepts also do a mysterious 6-bolt fishplate. *has anyone measured them? Martin.

Most chemicals are available in at least two grades. 100% pure Laboratory Grade, and a lesser/cheaper Commercial/Industrial grade. For example, ordinary commercial Meths is only 70% alcohol. I don't know about Butanone/Mek, but as it's a widely used industrial solvent in paints and adhesives I imagine the same applies. 100% pure Butanone is likely to be a much better solvent for ABS polymer than lesser grades. But that's not the main problem. Which is that Butanone does not dissolve raw plywood. The way to fix ABS to plywood is: 1. dissolve some chair sprues in Butanone until you have a thin gloopy mess. Or buy it ready glooped in adhesive cements such as Polypipe. 2. apply it to the plywood underneath the chair positions so that it penetrates the wood grain. 3. leave it to dry/evaporate. 4. you now have some ABS polymer embedded in the wood grain, and chairs can be attached to it with fresh Butanone. This was the method recommended by Exactoscale when they first introduced their injection-moulded chairs. Martin.

Sometimes it's because you are describing something you did 10 years ago, or using parts you have had in stock for years. You can't assume that similar products obtained fresh now will be the same. For example, it's well-known that some currently available bullhead rail no longer fits Exactoscale chairs properly, causing the base to bend significantly: Sorry about poor image quality, copied from Scalefour web site. If the chair base is not flat, with pure solvent you will be gluing only along the outer ends, and it will come away very easily. It needs a cement-type adhesive with some gap-filling ability, such as the Polypipe stuff. A possible solution, after threading the chairs onto the rail, is to run a soldering iron along the rail to soften the chair, and press the rail and chair down onto a flat surface as it cools. It's tricky to get the temperature just right to avoid damaging the chair or pushing the rail through the chair base. cheers, Martin.

@Haggerleases Hi, You wouldn't say that if you had ever tried filing and fitting them! If you are not in a hurry, and have access to 3D printing (yourself, or friends, or a club maybe), there is a new track-building process in the offing which I'm calling 3D Plug Track. No glue, no solder, no gauges, the chairs are a press fit in the timbers. The timbers can be 3D printed, or could be laser-cut from plywood: Some initial experimental stuff should be available in Templot in the next few days. More info: https://www.rmweb.co.uk/community/index.php?/topic/155917-3d-printing-chairs-and-sleepers-for-bullhead-track/&do=findComment&comment=4500290 cheers, Martin.