7mm Mickoo's Commercial Workbench
- Thread starter mickoo
- Start date
Eastsidepilot
Western Thunderer
Oh I don't know !Yeah forgot about them, living proof that my railway interest declines exponentially past the buffer faces
Allen M
Western Thunderer
Hi all
I have built a loco with split frame pick up so both frames are live. They are insulated from each other by using PCB for stretchers. Then between chassis and body there is a very thin sheet of plastic.
For US type pickup I would add the plastic and pit the fixing screw through an insulating bush. Result total safety.
Regards
Allen M
I have built a loco with split frame pick up so both frames are live. They are insulated from each other by using PCB for stretchers. Then between chassis and body there is a very thin sheet of plastic.
For US type pickup I would add the plastic and pit the fixing screw through an insulating bush. Result total safety.
Regards
Allen M
simond
Western Thunderer
mickoo
Western Thunderer
Another small update, the pony truck.
It's a nice example of fold up origami and with care results in a very nice pony truck, there are how ever a few pitfalls, hence this mini update whilst it's all still fresh in my mind.
From this angle everything looks fine and dandy, those that have built one of these before will note I've not added the fake spring overlay twixt bearing and axle box.
There's a good reason for this, it's half etch on the lower area on the inside and on the upper area on the outside, the transition between the two is not above the pony but just above the bearing.
The result is that the etch does not sit flat on the axle box face and thus tilts the top hat bearings; besides it's a very 2D affair and rather lets the rest of the assembly down, it actually looks better without it.
Reality is, I'll look at the real deal and work up a simple 3D print of the spring and supports and fit them later.
From below, again rather nice but the sharp of eye will notice some holes in the upper frame work where 0.8 mm wire needs to go to represent the bolts. Simple answer is, you can't once you've folded it up and you can only add the lower portion anyway.
The reason is that the front and rear transverse (the arched parts) fold up and block the hole from above, of course you only realise this once you've folded it......well y'all won't as I've just now warned you!
If you want to add these four bolts then you need to open out those holes before you bend up the transverse parts. To be honest, once the wheels are on the rim prevents you even seeing these four, so it's not great loss if they're not fitted.
Above from the rear, you can see the partially blocked holes where the front and rear transverse sections fold up, but, it also reveals the biggest issue, the upper stays that run back toward the pivot point.
Due to the fold up origami the only effective place they can fold up on the rear stretcher is where those two small tabs are folded over at each side on the rear transverse beam, these tabs will be removed shortly, but left here to show where the stays used to be attach.
The problem is the stay extends rearward a little before it kicks in toward the pivot point, sadly at exactly the same angle as the lower ones. The result is that the two tabs that attach to the lower stays end up being in mid air between the lower ones. Imagine the two upper stays simply moved inward by 2 mm each side.
A rough and ready photoshop to show where they would have originally been.
You can tweak them so that the rear end is moved outward, but, the brass is thin and in my case both broke off, besides, the front end would then end up with an odd angled dog leg affair when compared to the ones below.
Breaking off isn't as bad as it sounds, as it now allows you to put them in the correct place, in line (directly above) with the lower stays. By good fortune when the upper part is added to the top of the axle boxes it leaves a very small lip at the rear end. Also, by good fortune, when my stays broke off, a small part of half etch bend remained, this can be nestled onto the small lip area and soldered up.
I also swapped the left and right and flipped them, that way the half etch bend at the rear end is on the underside where it joins the lower stay, it also allowed the remains of the broken half etch bend to sit on the lip mentioned above.
Having done all that, someone will now probably come along and say the 47xx upper stays are offset in board
, I seem to have way laid my GA at the moment.
It's a nice example of fold up origami and with care results in a very nice pony truck, there are how ever a few pitfalls, hence this mini update whilst it's all still fresh in my mind.
From this angle everything looks fine and dandy, those that have built one of these before will note I've not added the fake spring overlay twixt bearing and axle box.
There's a good reason for this, it's half etch on the lower area on the inside and on the upper area on the outside, the transition between the two is not above the pony but just above the bearing.
The result is that the etch does not sit flat on the axle box face and thus tilts the top hat bearings; besides it's a very 2D affair and rather lets the rest of the assembly down, it actually looks better without it.
Reality is, I'll look at the real deal and work up a simple 3D print of the spring and supports and fit them later.
From below, again rather nice but the sharp of eye will notice some holes in the upper frame work where 0.8 mm wire needs to go to represent the bolts. Simple answer is, you can't once you've folded it up and you can only add the lower portion anyway.
The reason is that the front and rear transverse (the arched parts) fold up and block the hole from above, of course you only realise this once you've folded it......well y'all won't as I've just now warned you!
If you want to add these four bolts then you need to open out those holes before you bend up the transverse parts. To be honest, once the wheels are on the rim prevents you even seeing these four, so it's not great loss if they're not fitted.
Above from the rear, you can see the partially blocked holes where the front and rear transverse sections fold up, but, it also reveals the biggest issue, the upper stays that run back toward the pivot point.
Due to the fold up origami the only effective place they can fold up on the rear stretcher is where those two small tabs are folded over at each side on the rear transverse beam, these tabs will be removed shortly, but left here to show where the stays used to be attach.
The problem is the stay extends rearward a little before it kicks in toward the pivot point, sadly at exactly the same angle as the lower ones. The result is that the two tabs that attach to the lower stays end up being in mid air between the lower ones. Imagine the two upper stays simply moved inward by 2 mm each side.
A rough and ready photoshop to show where they would have originally been.
You can tweak them so that the rear end is moved outward, but, the brass is thin and in my case both broke off, besides, the front end would then end up with an odd angled dog leg affair when compared to the ones below.
Breaking off isn't as bad as it sounds, as it now allows you to put them in the correct place, in line (directly above) with the lower stays. By good fortune when the upper part is added to the top of the axle boxes it leaves a very small lip at the rear end. Also, by good fortune, when my stays broke off, a small part of half etch bend remained, this can be nestled onto the small lip area and soldered up.
I also swapped the left and right and flipped them, that way the half etch bend at the rear end is on the underside where it joins the lower stay, it also allowed the remains of the broken half etch bend to sit on the lip mentioned above.
Having done all that, someone will now probably come along and say the 47xx upper stays are offset in board
, I seem to have way laid my GA at the moment.
mickoo
Western Thunderer
David, the compensation beam is merely visual and very much truncated at the rear end.
I'm going to try and add one fixed at the front end on the pony, that stops just short of the rear one attached to the leading spring cross beam.
Maybe a laminated one with swaged rear ends to enclose (visually) the fixed one, that way the pony will still have full movement.
I'll also add some 3D printed axle boxes to fit on the inside to 'fill' out that area, it's very 2D fold up at the moment and easily seen from low angles when viewed from the front.
I've found my GA and the upper stays are in the right place, laterally, I.E line up with the axle boxes, but way to short, they should end up meeting the lower stay at the pivot point bend.
Now that I know this.......I'll probably end up taking these off and fabricating new ones....and....if I'm doing that, I'll probably add the reinforcing U brackets between the two and end up adding some sort of 3D representational blob to resemble the centre casting.
I'm going to try and add one fixed at the front end on the pony, that stops just short of the rear one attached to the leading spring cross beam.
Maybe a laminated one with swaged rear ends to enclose (visually) the fixed one, that way the pony will still have full movement.
I'll also add some 3D printed axle boxes to fit on the inside to 'fill' out that area, it's very 2D fold up at the moment and easily seen from low angles when viewed from the front.
I've found my GA and the upper stays are in the right place, laterally, I.E line up with the axle boxes, but way to short, they should end up meeting the lower stay at the pivot point bend.
Now that I know this.......I'll probably end up taking these off and fabricating new ones....and....if I'm doing that, I'll probably add the reinforcing U brackets between the two and end up adding some sort of 3D representational blob to resemble the centre casting.
mickoo
Western Thunderer
It had to change, knowledge is such a bad thing, once you know you have to modify to suit.
So off we went, a simple modification that took much longer to accomplish than write.
In basic terms new upper stays to the pivot point and then the inclusion of the supporting U shaped brackets.
Next up was a 3D printed centre casting, it's not 100% accurate, it doesn't need to be, it only needs to block the light and look like the real think at the required viewing angles, which are very small.
Never the less, now that I have a basic shape that fits the etch I can adjust and add detail at a whim and print and fit accordingly, I may add a few more flanges and nuts, none of which can be seen once fitted of course. There's a couple of pins to represent fixings, I over cooked them so they need scaling back to 0.8 mm to match the rest of the brass ones.
The fixing point is a bit of a quandary, it's a 6BA screw but the hole in the pony pivot is much too large, I've used may ways to solve this in the past, couple of washers laminated and turned to fit in the hole, the whole held in place with a nut; a short length of tube doing likewise as the washers.
This time I decided it was just as easy to turn one end of the 6BA nut to the required diameter and make the boss deep enough to allow the pony truck to swivel and tilt as required. The modified nut is upside down on the front plate work.
Was it all worth it?
Without centre casting......
With centre casting.......
It brings something to the party I suppose, it might be a bit more obvious once painted and some light weathering to add highlights etc. I did do some 3D inside axle box bearings to cover the 2D fold up affairs, they need some adjustments before a second print run tomorrow.
So off we went, a simple modification that took much longer to accomplish than write.
In basic terms new upper stays to the pivot point and then the inclusion of the supporting U shaped brackets.
Next up was a 3D printed centre casting, it's not 100% accurate, it doesn't need to be, it only needs to block the light and look like the real think at the required viewing angles, which are very small.
Never the less, now that I have a basic shape that fits the etch I can adjust and add detail at a whim and print and fit accordingly, I may add a few more flanges and nuts, none of which can be seen once fitted of course. There's a couple of pins to represent fixings, I over cooked them so they need scaling back to 0.8 mm to match the rest of the brass ones.
The fixing point is a bit of a quandary, it's a 6BA screw but the hole in the pony pivot is much too large, I've used may ways to solve this in the past, couple of washers laminated and turned to fit in the hole, the whole held in place with a nut; a short length of tube doing likewise as the washers.
This time I decided it was just as easy to turn one end of the 6BA nut to the required diameter and make the boss deep enough to allow the pony truck to swivel and tilt as required. The modified nut is upside down on the front plate work.
Was it all worth it?
Without centre casting......
With centre casting.......
It brings something to the party I suppose, it might be a bit more obvious once painted and some light weathering to add highlights etc. I did do some 3D inside axle box bearings to cover the 2D fold up affairs, they need some adjustments before a second print run tomorrow.
mickoo
Western Thunderer
I've used tube in the past, this time I couldn't be bothered to dig through my stock and find one that suited and trim it up. The modified nut above achieves the same, the turned section fits inside the etch pivot hole and when tightened up allows free movement of the pony truck.
It's kind of like a nut with a tube bush soldered on, so to speak.
And altogether a more elegant solution, but if you don't have a lathe to hand.....
(You're up late!!!).
3 LINK
Western Thunderer
Judging from the location slots for the cylinders, it looks like there is just enough room for the pony wheels to clear the cylinder covers when the loco is transversing curves , which is always a result.
Being a GWR fan this has caused a few problems over the years with the locos I have built, not a major problem, the worse case was having to cut a slot into the rear of the cylinders on a 42xx, and it looks like I might have to do the same with the Mitchell Castle that I am building at present.
Keep up the good work,
Martyn.
Being a GWR fan this has caused a few problems over the years with the locos I have built, not a major problem, the worse case was having to cut a slot into the rear of the cylinders on a 42xx, and it looks like I might have to do the same with the Mitchell Castle that I am building at present.
Keep up the good work,
Martyn.
mickoo
Western Thunderer
Then you can thread the nut onto some 6BA threaded rod (a bolt with the head cut off), attach in a Dremel and turn down with a file......
....Best stick to tube I think
Late, yes and paying for it now
Dave Holt
Western Thunderer
I think the centre casting representation is very much worth while. I can live with over-scale frame cut outs, to clear over-scale wheel flanges, but there's really no excuse to have clear daylight between trucks and bogies and the main frames. All full size locos have some means of transferring weight, so there's always lumps of metal blocking the gap. I like to make it functional (because I use sprung or compensated truck and bogie axles), but a purely cosmetic arrangement is preferable to a gap.
Dave.
PS. What happened to the MOK Ivatt 2-6-0?
Dave.
PS. What happened to the MOK Ivatt 2-6-0?
mickoo
Western Thunderer
Cheers, I think it adds something myself.
I added a basic form of oil bath to the last Bulleid and the smokebox light blocker with basic middle cylinder casting and blastpipe. Whilst neither were fully detailed they did enhance the overall feel of the model.
I do have a more detailed MK II pony casting printing right now, as well as some new inside front sand boxes, these are not in the kit, just a flat plate attached to the footplate overlay for the top of the sand boxes. The 47xx is quite open in this area so I think some 3D printed solid sand boxes will improve the look.
The MOK 4MT is a slow burner, the client is more than happy to let me progress faster priority models at the moment. I probably do a little more (a week or so) on it once the 47xx is done, just to keep it bubbling along.
mickoo
Western Thunderer
End of weekend update.
Fitted the pony axle box covers to the internal locations to cover up the 2D fold up etch, they also add a little mass when viewed low down at the front.
Before
After
It's a small thing really, just because I can I suppose. Revised the centre casting, added a bit more detail so it looks much more like the real thing, not that any of the extra work can be seen once it's on the engine, it's one of those 'I know affairs'.
Worked up some front internal 3D sand boxes.
From below they're barely visible, again one of those I know scenarios, sand pipe to be fitted in due course.
From above they are more noticeable.
I need to drill some holes for the filler lid retention spigot and the activation linkages and pivots; as such they're only fitted with double sided tape. they'll come out shortly for the extra work to be done before refitting permanently.
I do need to trim the pony pivot screw, whilst I can get the turreted nut on, it's a bit of a faff getting the etched bearing eye over the screw with the sand boxes in place. There's not a lot of room in there and I'm waiting until the slitting disc has reduced in size (dia) a little more before I attempt to reduce the screw height. Knowing my luck it'll break just before it reaches the required size!
Overall views of frames to date
Added frame overlays and built up the brakes, it is important to make sure the brake beam overlay goes on the right way, in this instance it is NOT
The rear pull rod to the weigh shaft should be on the right side of the engine, as should all the other pull rods.....when it's the right way up, not when you're working on it upside down. It is all removable, there being short pins at the hanger pivots that spring out of the frames, none the less, it's an almost total strip down of the brake rigging and rebuild. Hey ho.
Fitted the pony axle box covers to the internal locations to cover up the 2D fold up etch, they also add a little mass when viewed low down at the front.
Before
After
It's a small thing really, just because I can I suppose. Revised the centre casting, added a bit more detail so it looks much more like the real thing, not that any of the extra work can be seen once it's on the engine, it's one of those 'I know affairs'.
Worked up some front internal 3D sand boxes.
From below they're barely visible, again one of those I know scenarios, sand pipe to be fitted in due course.
From above they are more noticeable.
I need to drill some holes for the filler lid retention spigot and the activation linkages and pivots; as such they're only fitted with double sided tape. they'll come out shortly for the extra work to be done before refitting permanently.
I do need to trim the pony pivot screw, whilst I can get the turreted nut on, it's a bit of a faff getting the etched bearing eye over the screw with the sand boxes in place. There's not a lot of room in there and I'm waiting until the slitting disc has reduced in size (dia) a little more before I attempt to reduce the screw height. Knowing my luck it'll break just before it reaches the required size!
Overall views of frames to date
Added frame overlays and built up the brakes, it is important to make sure the brake beam overlay goes on the right way, in this instance it is NOT
The rear pull rod to the weigh shaft should be on the right side of the engine, as should all the other pull rods.....when it's the right way up, not when you're working on it upside down. It is all removable, there being short pins at the hanger pivots that spring out of the frames, none the less, it's an almost total strip down of the brake rigging and rebuild. Hey ho.
Last edited:
Yorkshire Dave
Western Thunderer
Ermmmmm.... as silly as this sounds why not use a permanent marker to draw a line or colour the excess pony pivot screw thread, dismantle it, put a nut on the screw up to the marked line/area, cut of excess thread, clean up, remove nut and replace the shortened pivot screw in the chassis.
Saves having to cut the excess thread whilst it is in the chassis.