tufnol(etc) spacers for insulation

[jon price]

Hi

I've tried (unsuccesfully, and not very actively) to find milled tufnol block for use as chassis spacers to go with split axles. Does anyone know of any supplier, or an easy to use alternative? With tender engines I think I'll use the American system, short the wheels to the axle on one side of the loco, opposite of the tender, and make sure the two are not linked in a conductive way, but for tanks I want an accurately dimensioned insulating block.

Jon Price 6540

[Russ Elliott]

http://www.collegeengineering.co.uk/Mat ... lsheet.htm

[Tim V]

I use double sided copper coated fibreglass, approximately 1.6mm thick.

I was able to mill tufnol blocks, but found hiding the screws that join the frames to it rather difficult.

[Philip Hall]

At Scaleforum either last year or the one before I got some milled Tufnol strips from Jeremy at the Stores, 14.1mm x 10mm. I got it to use for assembly of right - angled bits rather than frames. I can't see it on the current list, but might be worth asking Jeremy.

Philip

[Bob Ellis]

A simple and effective method I used to use before I acquired a milling machine produced gapped spacers quickly, easily and (most important) accurately from double-sided copper-clad fibleglass and lengths of 'U' shaped brass channel. The 'U' shaped channel needs to be a push fit over the thickness of the copper-clad fibreglass.

Use a vernier caliper to measure the thickness of the brass in the 'U' channel, multiply this figure by two and add about 0.2mm for clearance. Subtract this figure from the length you want your spacer to be when completed. Cut a copper-clad fibreglass spacer to this length and gap it. Cut two pieces of 'U' shaped channel to match the width of the spacer. Push fit one of the lengths of 'U' channel onto each end of the spacer. Place the assembly in your vernier caliper and close it up until it registers the desired length of frame spacer. The vernier caliper ensures not only that the spacer is the correct length but also that the ends of the spacer are parallel with each other. Whilst still holding the assembly in the vernier caliper, solder the 'U' channel to the copper-clad fibreglass.

Although I have not tried it, I assume this method would also work if you wanted to use tufnol or perspex rather than copper-clad fibreglass, although (of course) epoxy resin or superglue would need to be used in place of solder.

[BryanJohnson]

I can't remember where I got the idea from, but what I am part way doing for my current chassis project is to use the standard etched frame spacers to get the chassis mechanically complete, then use araldite to glue some stiff insulating material to the spacer before sawing through the brass to insulate the frames. I'll fill the resulting groove with araldite and file smooth. Has anyone else used this method?

I've built using cut copper-clad in the past, but struggled to get a set of spacers to a consistent and set width, hence trying the approach above. I have asked about pantograph milling a set of spacers but it seems that this is a bad material for the cutting tool.

I do like Bob's idea - I may try that next time. I guess that it's a prime candidate for using different melting point solders - high to fit channel to copper-clad, lower to fit spacer to frame.

[nigelcliffe]

A simple method I've used in 2mm scale is with thin double sided PCB and bent metal chassis spacers.
The PCB is soldered (flat face) to the frames. The metal spacer is formed and soldered to the other face of the PCB.

Result; the frame spacing is the width of the spacer plus two thichnesses of PCB.

I've used plain L-shaped spacers, and made U-shapes in a small press-tool which pushed out channel of predictable dimensions.

Double sided PCB (fibreglass core) can be bought as thin as 0.3mm. 0.5mm and 0.8mm are pretty common thicknesses.



- Nigel