Tuesday 5 June 2007

08 kit building - Part 6

Having completed construction of the N Brass rolling road (plus the extension kit ready for the 9F) I turned my attention back to the 08 last Friday evening. Dave Stratton had attended a chassis construction group and has his gears and wheels all installed now, so I was lagging behind.

I was unhappy with the worm gearbox on mine, and with just the motor and worm fitted (no gears) it was very rough compared to when the motor was out of the gearbox. Flexing the gearbox did allow the motor to speed up, but I just could not make it stay like that. Eventually I realised the gearbox had folded up not square. I removed the bearing from the far end and the worm rod was naturally hard against the side of the mounting hole rather than in the middle. I took the gearbox apart at the fold lines, filed the edges square and soldered it back together square, so that the worm rod was central to the bearing mounting hole, and when the bearing was added, the motor still ran smoothly and very, very slowly.

Now I think I stand a chance of making it work with some gears in position too. However, I want to blacken the chassis first.

Sunday 25 February 2007

08 kit building - Part 5

This Friday we had balsa wood (courtesy of Dave Stratton) so I could add the wires cut during the last session to the brakes. At this point we noticed that there are another set of brakes on the thinner etch. I presume these would have been easier to fold and drill than the ones on the thick etch, but maybe not so strong in use, so we will use the thicker ones.

Threading in the wires, and soldering up, as per the instructions,was straight forward enough, and the photo shows them with most of the wires trimmed and cleaned up. I will cut the remainder later, as I expect the length will be critical to hold them in place with the outer frames, without fouling the gear chain on the one side.

The next stage will be to paint or blacken the frames and wheels ready for final assembly before progressing with adding the cranks and connecting rods. There will be a few weeks gap before the next session, as we have our own Basingstoke Exhibition coming (March 10th/11th - very good value) and then we are helping Jim again at Nottingham.

Saturday 3 February 2007

08 kit building - Part 4

Last night's session started by me having to free up the rusting worm tube and extract it from the bearing. I cleaned it up again with emery paper, and got everything running freely again, but left it dismantled this time. I must put some oil on it to stop it rusting again.

Having dismantled everything, this evening was a less-than-exciting session of drilling .35mm holes (the smallest surviving drill I could find in my toolbox). Twelve holes in the chassis, and another 18 in the folded up brakes. However, Dave Stratton and I managed to complete all this without breaking a drill, which makes a nice change for me. I then cut 18 half inch lengths of .3mm nickel-silver rod ready for soldering,but as we did not have any balsa wood, that will wait for the next session.

Saturday 20 January 2007

08 kit building - Part 3

We were very pleased to be joined by Paul Martin for last night's session, but as he accepted some of our tea, he may well be back in hospital pretty quick. He had his 08 kit with him, and although he read the instructions and looked at the bits, we did not manage to persuade him to start construction - yet.

Dave Stratten and I started by cutting up bits of the axle steel into bits approximately 3.5mm long, using a vice and slitting disk. The gear muffs were drilled and reamed until the axle steel would push into them (1.6mm drill was used eventually).

I fitted the lay shaft with the gear at each end first, using a 1.5mm drill first, then pushing it through with one of the short lengths of axle steel. This method worked quite well. The larger gear was catching on the stretcher tab, so it was filed back a little to clear the gear.

Next would be the worm gear lay shaft. The muff for this one needed shortening as the bearings are further in. Another problem is the fitting of the gearbox over one of the bearings. Excess solder was filed away to allow it to fit, but it was apparent that one of the gears on the already fitted lay shaft needed to be away from the end of the muff to clear the gearbox. The smaller gear had been glued to the end of the muff last week, but the larger gear could be pushed right up to the collar to give clearance. It does mean that the gear train to the wheels is on the opposite side to the model in the instructions, but hopefully that will not cause more problems. To turn that lay shaft round, I had to file the other stretcher tab to clear the larger gear.

You can see the gearbox tab and how it fits next to the gears in the bottom left of the second photo.

Note that the tube that has the worm on it is rusting rapidly, although I am sure I did not get any flux near it.

With the two lay shafts and the gearbox in place, power was applied, and it whirred away smoothly, but slowly. Very satisfying, but I think it needs loosening up a bit. Not sure yet if the gearbox has to be fixed in place, or left to float.

Saturday 13 January 2007

08 kit building - Part 2

Last night's session was to be remembered for the things I forgot, like my glasses, and soldering iron.

First of all, I corrected the previous week's mistakes, as pointed out on the VAG. The errant frame spacer was repositioned to the top of the frames, and Dave Stratten let me have a spare motor bearing so that I could complete the gear box. Getting the worm onto the tube was tricky, but do-able. However, it seemed to close up the tube so that the motor not longer fitted into it. I therefore pushed the worm down towards the other end of the tube which the motor still fitted.

Having soldered the bearing in place, I could not fit the motor to the gearbox. Dave could fit his, but the motor would not turn when volts were applied. I therefore, unsoldered the bearing, assembled the gearbox, and then fixed the bearing where it wanted to be with a quick touch of the soldering iron. Dave did the same, and both motors whirred away happily.

Next came sorting out which gears go where. Hopefully the photo shows the correct arangement. I drill the muffs in the centre with a 1.6mm drill to aid in applying glue, and allowing air to escape. One of these holes can be seen in the photo. Most gears were a good tight push fit, but two of the small gears were rather loose. I filed a flat on the muff, and a key into the inside of the gear, and applied araldite (see the lower left gear in the photo). I also put some araldite into the worm tube and fitted it to the motor. Thankfully the motor still turns today.

The next stage is fitting stub axles, but as nobody had remembered to bring a minidrill to cut the axle steel, that will have to wait for the next session.

Saturday 6 January 2007

08 kit building - Part 1

Well, two more 2mm Scale Association 08 kits have started being assembled. Dave Stratton and myself commenced Friday evening, 5th Jan 2007.

After checking the box contents, and the contents of the CD on a laptop, construction started.The instructions are clear and well illustrated, but definitely not for the novice, as has been stated. It starts off with the jig: here it is on the etch, here is a photo of the completed item, get on and build it. Fair enough, we had no problems there. Next the bearings were soldered to the frames, fully populated for all axles gear driven, using the thought that it will be easier to leave out idler gears later than add more bearings.

Now it was time to solder in the frame spacers. The quantity and positions seem to be at the whim of the constructor. The instructions state that various ones are optional, but does not indicate which ones, or why. The photos seem to be of two different sets of frames with different spacer populations. I eventually opted to put in 6 spacers. I remembered an earlier post on the 2mm VAG, so I made sure all the tabs were as close as possible to 90 degrees. The PCB strip was a lttle wide, so needed a little filing to fit. Also, my nice neat insulation gaps were too far apart, and had to be widened for some of the longer tabs.Trial fitting the gears will have to wait until next week, as thesteel axle rod will need cutting up with a slitting disk. Therefore, I proceeded to put together the gearbox. Hmmm. The gearbox needs another bearing, but all the bearings supplied with the kit have been used up on the frames. Another job that will have to wait until nextweek.

Anyway, the results of my first session can be seen below, cruelly magnifying my untidy soldering.