relaxinghobby Posted October 20, 2014 Share Posted October 20, 2014 My Hornby Caley 0-4-0 saddle tank is in for heavy repair, that's because the cylinders have fallen off.So whilst I am glueing them back on which is easy as they are plastic card and tube, I can consider how to fine tune the mechanism.The chassis is one of the early ones with the big X04 motor.In an effort to tame it's speed and acceleration I had fitted a Romford worm and gear set and some Romford 14 mm wheels. Getting the gear to mesh smoothly was difficult and when I discovered that the model was inaccurate in that the tank and wheel base are too long compared to the prototype, I lost interest. It's was upgraded with the Romford parts years ago and I cannot remember the details, it looks like I filed the chassis a bit, see the the bear metal just by the gear wheel. That would have been to lower the motor down onto the gear.So the question is how to I adjust the depth that the worm goes into the gear wheel teeth, there is a tight spot at one part of the revolution of the gear wheel. An observation wheels have the older pizza cutter flanges not as neat as as the later RP25 shape treads and flanges. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted October 20, 2014 RMweb Premium Share Posted October 20, 2014 Maybe the Romford gear wheel has the axle hole drilled off centre? Does it still have a tight spot if the coupling rods are removed? ps Its not an 0-6-0! Link to post Share on other sites More sharing options...
Londontram Posted October 21, 2014 Share Posted October 21, 2014 If the chassis runs freely with the motor out then maybe when the chassis was filed down to much making the mesh too tight, you could try a very thin shim under the motor where its been filed off to see if this raises the motor slightly and thus making the gears mesh less tightly. Link to post Share on other sites More sharing options...
DCB Posted October 23, 2014 Share Posted October 23, 2014 The romforrd worm wheel tends to be a slightly loose fit on the axle and tightening the grub screw makes it run eccentrically, personally I have only had any success by drilling the axle and using a (12 ba?) bolt screwed into the axle to make the gear wheel turn with the axle. A Hole much bigger than the bolt so the worm wheel is a loose fit works especially well, but make sure the worm wheel is shimmed for side play, dont rely on the wheels controling side play, shim the worm wheel, this applies to all direct worm drive locos. Meshing an X04 with Romford gears is a problem the Romford worm-wheel is smaller than the normal Hornby worm-wheel and as the X04 has a lug and slot front mounting you may need to file the lugs and to drill and tap the hole in the lower pole piece and one through the chassis to take a bolt to hold the motor down, you will probably need to file away the chassis to allow the motor to sit down further at the front, if you go this route you can shim the motor up or down to get the mesh correct Link to post Share on other sites More sharing options...
relaxinghobby Posted November 20, 2014 Author Share Posted November 20, 2014 Despite the gear wheel being fixed with a grub screw it would not budge when the screw was undone. So I must have originally use lock-tight too, belt and braces . With one of the wheels removed leaving the other as something to hold and pull on I rested my soldering iron against the gear and in about ten seconds I could pull the axle out.Inspecting them on the bench I found that the gear was a tight push fit on the axle, probably due to the hardened lock-tight residue left behind. I've reamed out the gear axle hole and polished the axle with fine emery paper.I've sorted out some spacing washers, the thin brass ones from Romford Wheels themselves, to go over the axle and reassemble it all with the gear wheel nice and central. I introduced some lock-tight type fluid down the grub screw hole ( actually it's Lock-Thread from Grenville, it's what I found car spares shop ). I'll leave it to set until tomorrow. There is plenty of room for vertical movement of the motor in the chassis frame, it has already been filed in the original conversion. The problem is fixing the front of the motor at the right hight /position. The hole in the under frame piece of the motor is tapped to except a bolt coming up from the bottom of the chassis. The whole thing is a sloppy fit, my next task is to find a way of holding the motor still, in the right up and down position. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted November 21, 2014 Share Posted November 21, 2014 I would shim it as far fore and aft of the bolt as possible, until an optimum gear mesh is achieved. Tack glue the shims on so they don't move about and recheck the mesh, then stabilise the assembly with silicone or contact adhesive over as large a contact area as possible between motor frame and chassis, tighten down with the bolt and recheck the mesh. Leave it in a warm place for a week to thoroughly 'go off'. My efforts in this department typically fall down on 'leave it a week to go off', and I have to restart the process... Link to post Share on other sites More sharing options...
relaxinghobby Posted November 24, 2014 Author Share Posted November 24, 2014 Is cardboard an engineering material? Can I use it to make shims and spacers, should I replace it with plastic or metal of the same thickness ? Photo side view --------- you can see the card board there are two pieces under the motor, one under the brushes and one under the rear screw. If you look carefully you can see a tiny gap just above where the motor fixing lug is. It looks to be about 10 thou' I'll see if I can measure it. By the way these are old style Romfords, too many spokes, moulded in balance weights and a deep flange. Photo under view-------you can see the front motor screw it goes through a lump of lead that has been glued in between the frames. This is an early Triang/Hornby Polly chassis made from two sideframes of steel with solid spacers front and back leaving the centre with an open space which I had filled with lead.This set-up lets the motor and wheels tern freely on the bench, but because the gear and worm is hidden by the frame sides I can not see how deeply they mesh together. The top of the chassis has been filed down by about 1.5 mm so that the footplate can rest at the right height. The lump under the rear motor screw is the original height.If I run this set-up in as it stands, should I run with some metal polish or toothpaste on the worm to polish the teeth? Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted November 25, 2014 RMweb Premium Share Posted November 25, 2014 Is cardboard an engineering material? Can I use it to make shims and spacers, should I replace it with plastic or metal of the same thickness ? This set-up lets the motor and wheels tern freely on the bench, but because the gear and worm is hidden by the frame sides I can not see how deeply they mesh together. The top of the chassis has been filed down by about 1.5 mm so that the footplate can rest at the right height. The lump under the rear motor screw is the original height. If I run this set-up in as it stands, should I run with some metal polish or toothpaste on the worm to polish the teeth? I would let it run with the wheels off the tracks, suspended by the ends. The motor should run evenly in both directions, if the mesh is correct. If not try adjusting the tension with the screws at either end. No harm in polishing the worm, but won't help if the mesh isn't right. As for cardboard a fairly dense type would be best, but if it goes soft (such as if it soaked by oil), then you can select another material. At least you'd have an idea by then of exactly what thickness to use, for alternate materials. Link to post Share on other sites More sharing options...
relaxinghobby Posted January 5, 2015 Author Share Posted January 5, 2015 Even with the refitting of the worm and gear and using a cardboard spacer to reposition the motor slightly there is a bit of resistance when the motor runs. This mechanism can jam with the wheels at the same spot in there rotation. To try and get a better alignment between motor and worm I shall next try a fold-up etched gearbox. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted January 5, 2015 RMweb Premium Share Posted January 5, 2015 Even with the refitting of the worm and gear and using a cardboard spacer to reposition the motor slightly there is a bit of resistance when the motor runs. This mechanism can jam with the wheels at the same spot in there rotation. To try and get a better alignment between motor and worm I shall next try a fold-up etched gearbox. It sounds like the gear wheel might be eccentric - hole not bored in the centre. If so, no amount of gear packing will make any difference. (I suggested the same thing on 21/10/14 - any result?). Link to post Share on other sites More sharing options...
relaxinghobby Posted January 8, 2015 Author Share Posted January 8, 2015 Thanks to kevinlms' encouragement I've had another go. The loco jam at the spot at the same place when the wheel rotates is because the valve gear was jamming, i.e the small end pin was hitting the coupling rod. I've removed the piston rod temporarily, and the loco nows runs, even if it a bit hesitantly, which is due to a poor pick up. I'll have to reshape the pick up wire and/or build a wagon tender with pick up to provide extra pickups for the loco. Top speed is much more realistic now, but it has a coffee grinder growl even with PTFE lube on the gears. Maybe some fine tuning of the motor spacers is still needed. Maybe even a drastic rebuild into an 0-4-2, as the Caley did with some of theirs? Link to post Share on other sites More sharing options...
RMweb Gold teaky Posted January 8, 2015 RMweb Gold Share Posted January 8, 2015 It may just be photographic distortion but the wheel at the bottom right of that picture doesn't look like it is square on to the axle. Link to post Share on other sites More sharing options...
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