New chassis for the Hattons 14XX - Part 2
Entry posted by Captain Kernow
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I concluded the previous blog entry on this subject by saying that the next job would be to fettle the Perseverance frames to fit the Hattons/DJM body. These are the frames as provided on the Perseverance etch:
And separated from the fret:
The 'topography' of the underside of the Hattons/DJM footplate moulding called for some initial modifications to the tops of the Perseverance frames:
Further adjustments were subsequently made, particularly with regard to removing additional metal from the frames above the leading driving axle bearing holes.
The small piece of brass soldered to the rear of the lower side frame was due to concerns that the cut line was too close to the etched slot, but this didn't prove to be an issue.
In the meantime, the Mashima 1015 motor (which is all that would fit inside the mazak block) was given some gentle running in, prior to being fitted to the High Level gearbox:
The Markits wheels were also prepared to be attached to their axles. I find these days that I have to very carefully remove a bit of metal from the centres of Markits wheels, to get them to fit on their axles. I do this using a small, 4-sided needle file, which is fortunately a snug fit inside the wheel centre. Only a very few light passes with this file are necessary to get the axle to fit and I usually do one pass at a time and offer up the axle each time, until it fits OK:
I then put the High Level gearbox together. This consists of a special 'lash up', using components provided by Chris Gibbon. These are:
1 x LoadHauler Compact + gearbox, but not including the small drive extension that comes with the gearbox kit
1 x D2 DriveStretcher attached to the bottom of the LoadHauler Compact+, but with one third of the DriveStretcher removed
1 x D1 DriveStretcher attached to the end of the modified D2 DriveStretcher
The above then gave me sufficient distance to drive the leading axle and have room for the vertical part of the gearbox, plus the 1015 motor, within the space afforded inside the mazak block.
This is the gearbox 'lash up' before I soldered a 'stabilising' bar between the main gearbox and final DriveStretcher:
Some additional pieces of 2mm inside diameter tube needed to be cut to length, in order to keep the gears in the DriveStretchers on the correct side:
The completed 'lash up':
The gearbox under test:
And in the chassis:
Since taking the above photos, a number of c*ck ups (of my own making) have come to light. First of all, the whole reason for driving the leading axle was to enable me to fit single beam compensation on the rear driven axle and the pony axle. Unfortunately this wasn't possible, because I failed to allow sufficient space around the rear driven axle for the hornblocks, which inevitably intrude into the area occupied by the bottom of the main part of the LoadHauler Compact+ gearbox. The gearbox is a tad under 11 mm wide and the Perseverance OO framespacers are 11.5 mm wide, which just isn't enough room, so I decided to built the chassis rigid, albeit with some springing on the rear pony axle.
Unfortunately, in building the chassis rigid, I didn't use the chassis building jig to my advantage and resulted in the axle spacing on one side being very slightly longer than the other. As such, the chassis has been dismantled since the above photos were taken and is in the process of being soldered back together with more care.
In the meantime, I was beginning to have misgivings about the ability of the little 1015 motor to power the loco nice and smoothly, driving all those gearwheels in the process.
The stumbling block was the horrible lump of mazak, trapped inside the loco body. Removal of the side tanks/cab moulding from the plastic footplate moulding is necessary in order to remove it in a civilised manner, but that will break one or more of the lovely conduits arranged at the bottom of and the front of the side tanks, which then run down and along the footplate. The use of the 'soldering iron blade' to cut the plastic motor cradle out (as mentioned in the first part of this blog) had resulted in the plastic of the side tank/cab moulding and that of the footplate moulding getting fused together (in an area you won't see when the loco is completed), so having removed all the visible screws, including the two in the coal bunker, I didn't want to force the issue, for fear of causing irreparable damage to the loco body.
I had tried using my 12v mini drill, with appropriate burrs, to remove the mazak, but this didn't have enough 'grunt' to make a difference.
At this point, my good friend John F (Re6/6) came to the rescue and offered the use of his mains Dremel, so yesterday I went round to his place and together we wrapped the loco body up and masked it off, to try to keep it as clear as possible from 'mazak dust':
Well, the mains-powered Dremel certainly made a difference. One thing I hadn't anticipated (why, I don't know, because it is obvious when you think about it) is the amount of heat that the burr will make at high and sustained speed. I have John to thank entirely for bringing my attention to this and suggesting a coffee pause, to let the metal cool down, prior to the next session. This is what it looked like while we were having a break:
After a bit more attention, the mazak proved no match for the Dremel and the burrs and this is what we were eventually faced with when it was all over:
When we removed the paper wrapping the loco body, I was dismayed at the amount of 'mazak dust' that had found its way into the rest of the body, but this was easily removed in the end.
One casualty, though, due to my inattention, was one of the leading steps, where the rotating Dremel caught it:
I cleaned this up and made up a replacement lower step from nickel silver sheet last night:
The removal of the mazak block has now given a cavity about 23mm above the footplate and 35mm in length. That should be enough room for a 1020 and a slim flywheel, all being well. Here is a 1020 on test with the gearbox 'lash-up' this afternoon:
On the scale drawing, this is now the cavity that is available for a motor/gearbox combination:
Next steps will be to re-assemble the chassis and re-fit the motor/gearbox, see how that runs and see if there is room for a slim flywheel.
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