A discrete but practicable 7mm tiebar

[Hayfield1]

I must have pinched this idea from someone else, but I need a tiebar for my COT track test plank and I found these items lurking in a draw. A bit of head scratching and I came up with this idea to experiment with. For a layout I would take a bit longer with the design, but its a good start to test out a few ideas



I started off with a brass bar 1 x 1,75mm and a 0.7 x 2.5mm double sided copperclad strip



I cut 2 pads 7mm long and soldered the bar with 221 degree solder



A second pad was also soldered with 221 solder with the outer edges 38mm apart



The Tiebars were soldered to the top pads with normal solder and the tiebar extended by 15mm past the outer stock rail. The tiebar could be cut flush with the outer rail and stiff wire soldered to the bottom of it to join an angle crank or activator



I filed the copperclad pads angled into the tiebar to disguise them more.

They might not be as prototypical as some want, but so much better than copperclad strip

The photos are larger than life and in the flesh do look much better

 

[Pencarrow]

The only downside of a solid joint to a bar is that it doesn't allow for any rotation. Yes the rotation is only small, but if the blades are moved a lot the soldered joint will fail. Might be ok on a lightly used home layout but using the same approach we had numerous joint failures and blades coming adrift.

These failures ceased when we amended the approach to have pins dropping down from the underside of the blades engaging with holes in an under board stretcher.

 

[John_B]

0.7 x 2.5mm copperclad strip

Presumably double sided, so soldering it to the bar was both possible, and doesn't cause a short.

 

[Hayfield1]

The only downside of a solid joint to a bar is that it doesn't allow for any rotation. Yes the rotation is only small, but if the blades are moved a lot the soldered joint will fail. Might be ok on a lightly used home layout but using the same approach we had numerous joint failures and blades coming adrift.

These failures ceased when we amended the approach to have pins dropping down from the underside of the blades engaging with holes in an under board stretcher.

Chris

Thanks for the suggestion, this is an area of concern and by using a 2.5mm pad and tinning the actual joint hopefully I have minimized the potential issue

John

 

[Hayfield1]

Presumably double sided, so soldering it to the bar was both possible, and doesn't cause a short.

Yes, otherwise one side will not accept solder

 

[Bigjohn]

Picking up a point by Pencarrow, above, the P 4 system of twin droppers and use of a plastic bar sliding in SWISH curtain rail track requiring no tie bar at all (dummy if you wished) was one of the mast underrated advances in pointwork control

 

[Hayfield1]

Thank you very much for the reminder about turnout operating units, but I am not at that stage yet

In 4mm scale I have both the original Studiolith (curtain rail type) under baseboard units and the excellent Exactoscale turnout operating units.

But this is for 7mm scale and neither of these methods provide a tiebar which is my first aim, I understand there are at least a couple of versions around, one is impossible to fold up and I don't think the other is available

What I require is a simple to build, yet sturdy unit for a test/demonstration track, I understand I run the risk of a solder joint failing, but its an improvement to a copperclad tiebar

Your ideas have given me and others some thoughts on improving the operational side. Thanks again

John

 

[Bigjohn]

My adaption to 7mm scale worked well on my layout…….omega loops 6 BA bolts as adjusters to GPO type micro switches extended from Perspex sq rod……….

 

[PaulRhB]

Would it be possible to shorten the tiebar and put in an insulating cut then use brass pins soldered to the rails to provide pivots.

https://flic.kr/p/2qMZW1W

 

[Hayfield1]

Would it be possible to shorten the tiebar and put in an insulating cut then use brass pins soldered to the rails to provide pivots.

https://flic.kr/p/2qMZW1W

Paul

Thanks for the visuals, But I am trying to capture the look (visual appearance) of a tiebar, I have not yet got to the actual operating linkage to what ever means which will be used to change the direction and polarity

I don't want to hide the tiebar, but superbly have it on show. Replace Tiebar for stretcher bar

 

[Pencarrow]

I've ended up with a mixture of cosmetic and working solutions. Working: the blades are driven under-board by tortoise point motors (droppers from the underside of the blade into a sliding bar). Cosmetic: castings on the side of the blades with some thin plasticard in between representing the tiebar.

 

[Jordan]

They might not be as prototypical as some want, but so much better than copperclad strip

They do look good.
A few years ago when I built my track, here at the Back of the Class I cut the pcb strip very thin for the tie bar, rather than use a full-sleeper-width piece. Despite the rigid soldered joints, the switch rails have not come away from the tie-bar, albeit this is a 'lightly used' home layout.
Photo here of the skeleton switch. The other ties (sleepers!!) were coffee stirrer strips cut to size, spiked with Peco N scale track pins....

 

[Softvark]

I use a very similar method to Hayfield but instead of using copper clad as the tiebar I use 0.5mm phophor bronze wire. This crucially gives the flexibility to avoid straining the solder connection to the copper clad under the rails. It is quite strong enough to move the switch blades and I've even used it for double slips where it's moving 4 switches at once.

Credit to Jim Snowdon for this method which he described in the Gauge O Guild Gazette Feb 2015.

Julian

 

[Hayfield1]

My prototype is just what I said, something practicable to make and use with materials I had to hand. Once the method/design has been proven I can think of developing it further.

Thanks to all contributing to the thread, anything to rid us of PCB tiebars must be a step forwaed

 

[Pencarrow]

My prototype is just what I said, something practicable to make and use with materials I had to hand. Once the method/design has been proven I can think of developing it further.

Thanks to all contributing to the thread, anything to rid us of PCB tiebars must be a step forwaed

I actually think that the tiebar is the most difficult part of building points. Often seems to be an afterthought in kits and, as you say, just a slab of PCB used. I've never liked the PCB solution as it looks nothing like the real tiebar when used flat between sleepers.

The problem is that anything else can be quite hard to do, particularly as you have to maintain electrical isolation. I did buy some of those brass fold up hobbies but working out the complex brass origami was beyond me. No idea where the brass castings I've used and modified originated from but the trickiest bit there is getting them positioned in the right place.

 

[simond]

I haven’t tried this but it occurs to me that a fibreglass tie rod would be quite unobtrusive. The fishing boys use pultruded gf rod so it’s available from eBay and fishing shops, in sub 1mm diameters. It is stiff but not rigid, so would flex to accommodate the point operation. It could be epoxied into those brass casting thingies once they’re soldered to the blades, rather than the wire.

(it works for cast metal brake shoe pivots too - I have done that)

beware carbon fibre, which is stiffer, more expensive, and conductive…

now, Chris, where did the cast brass thingies come from?

 

[Stephen Freeman]

For double slips I do the the two pairs separately and then connect them together, it's just easier that way. The Exactoscale method is generally to be preferred in my opinion as the stretcher bars can then be purely cosmetic.

 

[Pencarrow]

I haven’t tried this but it occurs to me that a fibreglass tie rod would be quite unobtrusive. The fishing boys use pultruded gf rod so it’s available from eBay and fishing shops, in sub 1mm diameters. It is stiff but not rigid, so would flex to accommodate the point operation. It could be epoxied into those brass casting thingies once they’re soldered to the blades, rather than the wire.

(it works for cast metal brake shoe pivots too - I have done that)

beware carbon fibre, which is stiffer, more expensive, and conductive…

now, Chris, where did the cast brass thingies come from?

I've had a dig around and it appears they came from C&L. Interestingly, two packets, same code, different contents. No idea if still available. I think I got most of mine second hand.

 

[Richard]

I used the MM1 tie bar kits which were a left hand and right hand etch which were joined together with an epoxy coated bit of paper to provide the insulation. They provided a decent length of brass to solder along the length of the switch rail(s).

With MM1 currently closed, and the future availability of these uncertain, I'd be tempted to draw up something similar, and get them etched in nickel silver.

 

[martin_wynne]

Templot plug track and COT track already includes an option for an invisible slider running under the ballast (not under the baseboard), allowing cosmetic dummy stretcher bars above it:

In 7mm scale this works for both THICK and MEDIUM timbers options:

What we haven't yet done is post the STL file for a resin-printed slider. It would be gauge-specific. Anyone?

In the meantime it shouldn't be too difficult to make a slider (file the side angles on tufnol or similar?).

The pin is retained in the slider with a soldered collar (not strictly necessary, but it makes assembly easier) which might be a small washer or a wrap of copper wire.

The top of the pin is bent over and soldered to the foot of the switch blade in the usual way.

If suitable pins are hard to find, the pin could be replaced with 1mm brass wire, bent over at 90 degrees below the slider.

The slider ribs are angled at 45 degrees to enable the ribs to be FDM printed more accurately. The short slot in the slider (rather than a plain hole) allows for the curving of the open switch blade.

The whole gubbins is hidden below a thin card or thick paper cover which can have some ballast sprinkled on it and/or be covered in the usual track gunge, having a couple of openings for the pins. If made from paper, the openings can be simple knife slits, which would close round the pin very effectively.

Dummy model stretcher bars can then be added, which can be resin-printed and fully detailed. This drive design also maintains full daylight below the rails between the timbers, not relying on the underside of the stock rail to hold the switch blades down on the slide chairs -- the slider does that. On the prototype the stretcher bars do that, and can be modelled with dummy extensions. (And full dummy rodding added, if wanted.)

cheers,

Martin.