Hi Guys,
I have recently purchased a Backwoods miniatures double fairly kit, which I was thrilled to get. However, the 1.5mm layshaft had been changed to 2mm, also the two separate reduction gears were now fouled as one, and the number of teeth had been changed by Backwoods. The holes to take the various bearings were already etched into the fret, and can therefore not be in the wrong position, but the final axle drive gear is meshing far too deeply into the reduction gear. Have any other members experienced this, and does anyone know where to obtain suitable replacement gears. I have tried topping the nylon final gear, and then re-profiling the leading/training tooth edges, but rather unsatisfactory I am afraid. Any suggestions (police ones) would be much appreciated.
Regards to all
Norman
I've not got one of these myself but hopefully a few pointers may help.
I'm assuming that you have purchased this kit second hand. On that basis it's possible that the 2mm layshaft and "two separate reduction gears were now fouled as one" (not sure what you mean by that description, unless it is a 1 part 'compound' gear - larger and smaller diameter gears moulded in on part - that has replaced 2 gears that you mount together on the same shaft) are not original 'Backwoods' parts but replacements by a former owner of the kit for reasons unknown.
From memory the Backwoods kits use gears obtained from High Level (https://www.highlevelkits.co.uk/), so in the first instance it may be worth contacting them to see if they can sell you some replacements, or confirm what the original specification for the gears were.
Knowing the 'correct' specification gears will be useful if you then need to go elsewhere. I've had some success sourcing gears from Mikroantriebe (https://www.kkpmo.com/) so they might be worth a try, and I suspect that there may be other sources in the former 'eastern block', but I've yet to find anywhere in the UK that can supply these sorts of items at a sensible cost / timescale.
The other thought is that in opening the original holes for the 1.5 mm layshaft to 2 mm for its replacement you have managed to move the hole and the centre of the layshaft towards the final drive axle, thus increasing the depth of mesh. In theory it should be possible to measure the new centre distance to sort out what size/pitch gears you would need to get a correct mesh, but I suspect that will need one or both gears to be replaced, especially as a replacement etch is unlikely to be available any time soon.
That's probably not the good news you wanted to hear, sorry...
The gears are all MO,3.
I replaced all the gears in mine so as to get a central mesh with the worm wheel.
The idler shaft gears are 25T, 1.5mm thick and 1.5mm bore. Also 12t, 2mm thick and 1.5mm bore.
The bottom output gear is 25T, 1.5mm thick and 2mm bore.
Here is a link to the company. I have had good service from them on numerous occasions. I think a link to this company needs putting up on the 009 web site as queries for spare gears often come up.
https://shop.kkpmo.com/index.php?cat=c27_M0-3-spur-gear---gearwheels---pinions-M0-3---Gearwheels---Pinion---Spurgear.html
If the holes in the gearbox for the idler shaft have been opened up you can easily bush it with brass tube or you could order the gears with a 2mm bore. This might not leave much material left on the 12T gear.
Thanks Alex & Julian, Very useful contact details, and yes this would be a useful link on societies pages.
Yes they are compound gears, and, being a retired clockmaker, I know that the correct centres were maintained, the gear diameters must be fractionally different.
Thanks a lot for your input.
Regards
Norman
Andrew (Webmaster) has now added a link to KKPMO/Microantriebe on the 'Links' page of the Society website.
Julian