[Richard Johnson]

QUOTE (wiggy25 @ 13 Jun 2008, 21:09) <{POST_SNAPBACK}>Does it look like this?

Looks like Key kits do a 4-2-2 chassis:-

KEYKITS milestones range

ML6/9 Looks like the one....No excuse now

***Hi Ian

If its the pills making you do it then please keep taking them - and if you can spare a few, send me some!

I love building loco's (my favourite part of the hobby) and think your project is an excellent one - there's nothing more satisfying than creating something thats uniquely your own handiwork.

Richard
DCCconcepts

 

[Richard Johnson]

QUOTE (wiggy25 @ 15 Jun 2008, 01:56) <{POST_SNAPBACK}>The bearings did stick out a fair bit on the outside, it says file them down if your short of space, so I filed them down anyway as I don't know, better then than when it's all built!

Question for those in the know, the worm gear on the motor shaft and the idler gear are both held on by a very small grub screw, does any body put loctite on these, not glue!!
I have a range in my works tool box from super concrete I think thats 243, to just thread lock which isn't so bad, or do you just not need to bother?

Cheers

***A good start Ian, well done. Do read & follow the chassis assembly advice from Comet - it will help a lot.

When you mount the gearbox on the axle, use some etched 1/8" washers on the axle each side to keep it loosely centralised between the frames. If U can't get etched washers you can use stamped ones but rub each side on some medium wet and dry t reuly flatten them (they get a wee cusp when stamped and that makes them not so smooth). Ditto to keep the final gear in best position for the intermediate gear.

Re fixing the gears, I actually prefer to use Loctite and no grub screw at all as the grub screw will very slightly decentralise the gear and can cause less than perfect running. Never had a gear come loose doing it this way, but boy they do seem to stick like S to a blanket when U want to remove them .

The loctite I use to fix the gear is the stronger one - not a simple gentle thread locker - I can't remember the number but its green... I think its used to secure steel pins and studs in engine blocks etc so they won't ever move.

the benefit of using loctite as the primary gear fixing is that it really flows around the axle and helps perfectly cetralise the gear (even though they feel like they are a tight fit, they will move to one side or the other if not centralised somehow)

If you are nervous about no grub screw then file a small "flat" on the axle only where the grub screw goes & then drill the axle to take the tip of the grubscrew with a little clearance and then you can seat it "just home but not tight" and lock it in place with a wee bit of glue to stop it loosening, actually securing the gear to the axle with loctite. Then if the loctite still lets go the gear will still be keyed to the axle with the grubscrew and you'll probably not notice.

When you loctite the gear to axle: first clean it and the gear / bearings thoroughly with some solvent. Put it as close to "in position" as you can. put a wee bit of oil on the outside of each bearing and rotate the axle to coat the bearing/axles only, then apply the loctite into the grubscrew hole with a pin or something similar. turn the gear a couple of times while holding the axle to spread the loctite - let the loctite flowing round "centralise" the gear and go off before seating the grubscrew.

Try not to get too much in the grubscrew thread but if U do don't worry - its only messy as the Loctite won't usually go off in the grubscrew hole as its thixatropic - it only sets in when in a thin film between parts and when air is excluded - most loctites also only "go off" when in contact with steel - ie the axle.

Regards

Richard
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[Richard Johnson]

QUOTE (wiggy25 @ 20 Jun 2008, 23:12) <{POST_SNAPBACK}>Ok so I have no idea what I'm doing!

I have the Romford wheels and crankpins and spacer washers.
Reading the instructions, I place the connecting rod onto the crankpins of the two large wheels, followed by the coupling rod from one large wheel to the crosshead valve mechanism, on top of this fits the return crank.

Then what, do the washers fit on last thing?
Are these washers soldered to the crankpins to hold the connecting rods on?

I'm a bit lost now, instructions do tell you which order to put everything on in but not where the washers go or how you fix things to the crankpins, any help would be useful!

Cheers

***

Ian, I'll try to help but I'm doing it blind not having the same kit to hand - the techniques are mine - you can vary or follow other instructions If U have them...

DO buy the Iain Rice book on building loc's - it explains all this stuff really well!!

So have U got the gearbox installed?

This should be on and tested as smooth running with the centre axle/drivers and then all the wheels in the chassis and properly quartered before U solder the rods on.

fitting the rods... Before U solder anything, test the chassis with the rods on.

place them over the crankpins and use some insulation stripped from wire slipped over the crankin to hold them. If the alignment of rods and crankpins is good, and you have got the quartering right (one side all 90 degrees offset from the other) it should run very freely.

If not you will have to look closely at the rods at the tight spot where it binds and find which rod it is... carefully open out that specific connecting rod hole only left and right only with the tip of a round fine needle file.

For the front and rear driver crankpins:

Before putting the rods in place paint around each hole both sides with a spirit based texta of felt tip pen - this helps stopping solder going where U don't want it.

Now put the cranks in place, cut a tiny bit of thin paper (standard typing paper etc) and make a small hole in it. Put it onto the crankpin. Now, slightly countersink one side of the turned washer and slip it onto the crankpin with the slight countersink facing you. press it doen gently so it slightly cmpresses the paper between washer and rod and carefully solder the washer to the crankpin.

(the paper stops solder and creates a slight spacing for free running. the countersinking allows a fillet of solder for a strong joint and it will that there then it will not let go when U later carefully clip the pin and file it flat to the washer face)

repeat with other side.

Now, the centre pins / crank .

I'm flying blind as I don't know the detail of the kit U have but generally one washer goes on the centre pin after the connecting rod is in place, then a thin bit of paper, then the crank.

If your kit asks for it be sure you did the two slight bends in the crank to create the vertical offset for the clearance of the valve rod before you start this!!

tin the face of the crank boss with a very very thin coat of solder then slightly countersink the hole in the etched crank on the side facing you with a fine drill hand-held and place it on the crankpin. Make sure you get the right position - usually about 20 degrees leading. Check your prototype for this!!

Solder the crank to the washer and crankpin carefully and quickly - be very sparing of flux on all these joints - and be quick. the paper washers & texta will prevent solder sticking the ther side of the washer to the connecting rods.

You will now need to clip off and file the front and rear pins flat. However test run the chassis again before trimming the centre one as you may have to remove it or adjust it and that easiest with a long pin. connecting.

Don't forget to remove the paper washers you used as a solder barrier... (I usually just wet them with a little oil and they work their way out assisted by a bit of judicious help from a scalpel tip)

Good luck....

Richard
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[Richard Johnson]

QUOTE (wiggy25 @ 20 Jun 2008, 23:59) <{POST_SNAPBACK}>Thanks Richard,

This is the link to the loco that I'm actually building!

Schools class

Hopefully that should help!

Cheers

***Help who Ian??

Generally the advice applies OK to the asswmbly & valve gear as I wrote it... What I meant was I don't have the specific kit in front of me as there can be small changes maker by maker that need small technique changes - however looking at the loco I'd say you can do it as I said it in general, except that I wrote it for a 6 coupled not a 4.

The 4 will be easier to get smooth - only two crankpins each side is an easy (easier anyway) path to tread!

regards

Richard

 

[Richard Johnson]

QUOTE (wiggy25 @ 21 Jun 2008, 17:56) <{POST_SNAPBACK}>Thanks Richard,

The advice about soldering on the crankpin washers is what I needed to know.
Having never fitted any, didn't have a clue.

The link was just meant to give an idea of what I'm building, I doubt if the body will look that good though!!

Need to test run it then paint it all, before any of that, which is going to have to wait!

Not slept properly in 4 days and the pain down my leg is crippling, pain killers just make me constantly feel sick.
This is not good! Hey ho MRI on Monday, then another week before I see the results to find out whats going to happen!
Nightmare!

Anyway will try and get some photos of the chassis, it's all nearly complete, should be able to connect most things up and run it up and down to see how it goes.
Trying to work out if there's a way of connecting the return crank and valve arm to the crankpin just to test the complete motion without soldering it all up.
Will look into that one!

Thanks again for the info, exactly what I needed!

Cheers

Good luck Monday Ian

No, there's no way to fit the crank without soldering it up - but once you have tested the connecting rods as mentioned there will be no real need to either.... just check that the crosshead moves smoothly on the slidebar and it'll be fine.

Be confident - you are doing fine!

But:

DO get the book by Iain Rice - its published by Wild Swan I think... Iain writes really well and makes it sound interesting and easy - it'll be the best couple of quid you'll spend for a long time!! ...and it'll be something useful for you to read when the pills make working on the model a no-no.

Richard

 

[Richard Johnson]

QUOTE (dwb @ 21 Jun 2008, 18:46) <{POST_SNAPBACK}>A "touch" of Loctite which is designed to stick but which breaks if you try to "shear" the join? ie the objects joined won't pull apart but if you twist them - hey presto they do?

David

***Loctite only goes off in the presence of steel... none there to help it I'm afraid.... its all brass or nickel silver... PLUS its formualted to creep into joints so it can't be stopepd creeping deper in the valve gear which would gum it up anyway.

Anyway... Basically it can't be done with glue or it'll likely compromise the later soldering... but there's no need to either, if the quartering is right (and it will be with the self quartering axles Ian has) and the connector rod spacing is good (which is will be with a newer comet kit) then it'll be just fine.

Richard
DCCconcepts

 

[Richard Johnson]

QUOTE (dwb @ 22 Jun 2008, 06:40) <{POST_SNAPBACK}>I was speculating on what might be needed. So Loctite don't do anything suitable. Is there a gap in the market or is it just Ian that needs something like that? I'm not a chemist so I can't help.

Thanks for the extra info Richard. I shall try to remember it, especially as I would one day like to follow in Ian's footsteps and build a chassis for myself, but I think I might choose an inside cylinder 0-6-0 to start with...

David

*** If you start with a more recent DJH Kit you'll do it standing on your head - they go together easily and in general instructions are excellent. Have a go!

Richard