Steam up

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David B
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Steam up

Postby David B » Fri Mar 24, 2017 4:39 pm

I started my second loco at the recent Missenden Spring Weekend. As a dedicated GWR modeller, a GER Y6 tram loco might seem out of character but I have always loved these locos so bought one when Paul Willis got Jim McGowan to do a limited run. My thanks to Paul a) for getting the kit out and b) for his help at Missenden.

I am very much finding my way with chassis but I have made this one with a couple of new(ish) ideas.

First, the loco build so far:
Y6_4790crw.jpg
Y6_4790crw.jpg (85.04 KiB) Viewed 8581 times


Over the years I have been watching other modellers and thought 'that's a good idea' or 'I will not be doing that!' and in the latter cases, thinking up what I feel might be a better way. How many times have you seen someone fiddling with a screwdriver to remove a chassis, followed quite rapidly with either the 'bum-up' pose on the floor or cursing because the *** screw won't go in the hole?

My thoughts turned to magnets. No-one has yet come up with a way to magnetise brass, so I have used the butt end of a scalpel blade, snapped and ground to fit a Masokit door droplight frame and soldered under the floor. You have to think ahead here in order to make sure the frame spacer you are attaching the magnet to is the thickness of the droplight frame below the top of the chassis frame. I also put the magnet across a hole to reduce any negative effect to the magnetic field the brass might make. The magnet is 10x3x2mm neodymium which I bought from First4Magnets, stuck in with some double sided tape. I am sure there is scope for improvement here! The slot in my spacer is to clear the coupling.

To keep the chassis aligned, I soldered the droplight frame against one side frame and packed the other side out to the correct width with scrap etch.

The other end of the chassis slots below a cheesehead bolt (8BA) soldered in to a tapped hole in the floor and filed off flush. In this case, I wanted to avoid a nut showing in the cab; elsewhere this might not be so important. The lumps inside the spacers are bits of lead ballast.
Y6_4784crw.jpg
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When I made my other loco, 4600, I used a 2-pin plug to connect the motor. This meant that if the polarity is wrong, it is simply changed and if at any time the motor comes out, I do not need to unsolder anything. It means you only solder to the motor once. I have used decoder wire which is rated at 2amps. The socket is soldered to a piece of copper clad, across a break.

As this loco has a hidden chassis, I decided to use top wiper pick-ups as I did on 4600. Not being underneath the loco, these pick-ups are not vulnerable to damage, being caught by fingers or padding in the stock box. I think they also make a 'cleaner' chassis and intend to use top wipers wherever possible. I will come to the wipers in a moment, but to complete the 'between the frames' bit, I have used 0.7 brass wire, soldered to the copper clad and passing through the chassis inside some plastic tubing.
Y6_4785crw.jpg
Y6_4785crw.jpg (81.42 KiB) Viewed 8581 times


The actual pick-ups are made from 0.35mm phosphor bronze wire. I coiled it round some 0.7mm brass rod three times with a tail at each end. This was slipped over the rod sticking out from the chassis and secured with a 14BA washer soldered on the end. (Note: You must trim the brass wire back to clear the connecting rods first. Guess who did not!) The end of the p/b wire has been bent up, back then down to form a loop over the flange of the tyre, making sure it cannot touch the chassis side frame. This is to keep the pick-up on the tyre, not in front or behind.
Y6_4788crw.jpg
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Paul Townsend
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Re: Steam up

Postby Paul Townsend » Fri Mar 24, 2017 6:41 pm

Interesting innovations there. Now to build a Broad Gauge version!

Philip Hall
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Re: Steam up

Postby Philip Hall » Fri Mar 24, 2017 8:08 pm

David,

Very neat work. I would just counsel caution with using phorphor bronze wire against steel tyres. Oxidation is a problem with P/B against steel tyres (per Mike Sharman years ago) so I use 0.3mm hard brass, almost as springy. P/B is fine with nickel silver tyres, so Ultra scale wheels and P/B pickups are fine. It is true that RTR chassis always have P/B pickups, but there are often more of them so the problem is mitigated.

Philip
Last edited by Philip Hall on Sat Mar 25, 2017 1:47 am, edited 1 time in total.

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David B
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Re: Steam up

Postby David B » Fri Mar 24, 2017 8:17 pm

Thanks for the word of caution, Philip. I have not had any problem yet with 4600 over the past 5 years.

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Will L
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Re: Steam up

Postby Will L » Fri Mar 24, 2017 10:09 pm

Philip Hall wrote:..I would just counsel caution with using phorphor bronze wire against steel tyres. Oxidation is a problem vwith P/B against steel tyres (per Mike Sharman years ago)...


I have a great respect for Mike Sharman, but when he gave rise to this one I'm afraid the great man slept, and Ian Rice just followed where he lead.

May be true if you run your chassis in salty water but your dry chassis is quite safe. This is just as well because in terms of the chemical property which underlies this "missunderstanding" brass and phosphor bronze are not significantly different. If it really did happen with phosphor bronze against steel it would also happen with brass.

Galvanic corrosion is what this is, or isn't, all about. Ships in salty water have significant problems, delicate machinery in a damp atmosphere might need to take it into account, your chassis will have no problems. More information than you want here.

Can we please not hear this one again.

hughesp87
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Re: Steam up

Postby hughesp87 » Fri Mar 24, 2017 11:24 pm

David,

I've used PB wire with steel tyres for the last 25 years with no problems. One slight difference in my case is to bend a small V into the end of the wire so that contact with the tread is only at the point of the V. This reduces friction with no loss of efficiency.

Lovely models though. I'm a bit close to the Wisbech and Upwell here, so the sight of something like this is very tempting!

Regards,

Geraint
Geraint Hughes
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Philip Hall
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Re: Steam up

Postby Philip Hall » Sat Mar 25, 2017 1:45 am

Will, point noted, but I have had the odd problem from time to time which is why I avoid the mixture where possible. Sometimes I use very fine nickel silver wire.

The RTR use of P/B has, as I said, not given me many problems, although the spring pressure is often very heavy and difficult to adjust. Which is another reason why I like very fine brass or nickel silver (0.3mm or less) as the pressure can be very light.

Philip

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David B
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Re: Steam up

Postby David B » Sat Mar 25, 2017 8:47 am

I don't think it really makes a lot of difference whether one uses p/b, n/s or brass wire. I have used the p/b because I have the wire and I have seen it used widely, especially in rtr. I think the important thing is for it to be thin so that it is springy whilst not creating excessive drag. With the power of today's motors I am not sure that a V shape or wire against the tyre will be very different either but I take the point (no pun).

Has anyone else used magnets to attach chassis? They make chassis removal very much easier.

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Will L
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Re: Steam up

Postby Will L » Sat Mar 25, 2017 2:16 pm

Philip Hall wrote:Will, point noted, but I have had the odd problem from time to time which is why I avoid the mixture where possible. Sometimes I use very fine nickel silver wire.

Which you will note from the Wikipedia article is more corrosive combination with steel (in the wrong circumstance) than brass or phosphor bronze
The RTR use of P/B has, as I said, not given me many problems, although the spring pressure is often very heavy and difficult to adjust. Which is another reason why I like very fine brass or nickel silver (0.3mm or less) as the pressure can be very light.

Pick up design (bin there done that) does of course need to suit the materials use. Some people find that brass wire tends to be a bit too malleable for something that is intended to be springy, while P/B springs are much better at retaining their shape, as anybody trying to straighten P/B off the reel will have noted.

David B wrote:...Has anyone else used magnets to attach chassis? They make chassis removal very much easier.

Not as such David, but I too go for a fixed point at one end that the loco the chassis hooks under. Although I have always use a nut soldered to the body and a bolt to finish the job, by the time I've fitted (the operative word) the chassis to the body attached all the plumbing etc and got the motor slipping glove like into the space not taken up with weight, I find the chassis tends to pop into place. I can well imagine that a magnet would be more than enough to stop the chassis popping out again unexpectedly. You will just have to make sure you had something strong enough to pull on to brake the magnets grip.

Philip Hall
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Re: Steam up

Postby Philip Hall » Sat Mar 25, 2017 5:50 pm

I think this must be one of the many instances where our own preferences and experiences may be at odds with the true technical explanations! It's been interesting to hear these viewpoints.

As for magnets, many thanks, David for the idea. I have a GWR 42xx on the go at the moment (not a Hornby conversion, a kit build this time) which would be an ideal tryout for this form of fixing. When I built a 72xx from the same source getting a screw in to hold the front end to the chassis was a real fiddle, so I have just ordered some of the little magnets today.

Philip

billbedford
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Re: Steam up

Postby billbedford » Sun Mar 26, 2017 7:25 am

There is a reaction between phospher-bronze and some of the foam plastics that are used to line stock boxes. This can lead to uncertain running after taking the loco out of its box and placing it on the track.
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David B
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Re: Steam up

Postby David B » Sun Mar 26, 2017 8:05 am

I suggest that if there is any more on various reactions between materials, a new thread is started elsewhere. It would be easier to find for future reference.

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David B
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Railmotor

Postby David B » Wed Jan 30, 2019 10:24 am

In the topic on resistance soldering, I posted some images where I was applying overlays to Jeremy's rail motor chassis. Stephen Howe said he would be interested to follow my building of the chassis and I have received a few more requests, so here goes.

I would recommend any of you to read from end to end, Jeremy's own building of the chassis. I am sure we all find some different ways to achieve the same end product and I am no different, so there are some small deviations from Jeremy's workflow in what follows.

The first of these is that having cut out the frames and spacers, the first job I did was to put in the CSB knobs. I found this much easier to do with the frames flat. A short length of 0.4mm wire threaded through the knobs keeps them lined up. I made the rear spacer together with it's overlay and the lifting lugs before I put it to the frames and although I used 145 solder throughout, it could be made with 180, 145 being used to attach it to the frames.

Don't make the mistake I made - on seeing a half-etched line, I folded it. The half-etch line here is to locate the vertical part of the spacer which a fraction longer than the bottom part, fitting in the etched notch on the frame. I added the overlay, cleared the slots and added the lifting lugs.

Rear-spacer_3438crw.jpg

The middle spacer is folded top and bottom, the top having the two notches through which the CSB wire fits. Make sure the frame is square - the only 'bracing' at this point are the spacers. The boiler base, the big bit with a large hole in it and two parallel etched lines, will make it rigid but this goes on much later.

A tedious job, but well worth it, is to take the time to remove the etching cusp from parts wherever possible. The end result looks that bit better.

Next fit the hornblocks/bearings and here it is important to file off the etching cusp. Make sure the block slides freely - the slot is off-centre and the thicker portion goes inside the chassis. The outer portion is about the same thickness as the detail overlay.

I have shown how I added the overlayselsewhere but will do so again briefly here.

Tin the overlays. Fit a bearing, flux the frame, place the overlay in position around the bearing, move the bearing down and apply either a clean iron or RSU. The two rows of rivets go towards the centre of the chassis.

overlay_3412crw.jpg

overlay_3413crw.jpg

overlay_3414crw.jpg

overlay_3415crw.jpg

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David B
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Postby David B » Wed Jan 30, 2019 11:03 am

Next come the cylinders. These need thinking through if you are to make life easier later. There are quite a number of parts and more that are going to be fitted, 13 or so plus some tubing. The tube for the piston to slide in is 1.5mm o/d, 1mm i/d. Going further ahead, I have used 0.5mm nickel silver wire for the piston rod, so I also used some 1mm o/d, 0.5i/d tubing.

cylinder_3429.jpg

Before I put anything together, I made sure the 1.5mm tube would pass through the piston stem guides (4 + a half-etch) and cylinder end frames. The best tool is a broach. I cut one hole then marked the broach and cut the rest to the same place on the broach.

broach_3439crw.jpg

Here is a piston guide. I have inserted a short piece of 1mm tube, to take the piston, which only goes in to the larger tube by about 1mm. Alternatively, you can leave this out, as Jeremy has, and have a larger hole. I feel the narrower tube makes for a more positive fit but it is not essential.

stem-guide_3417crw.jpg

Not only does the piston guide tube got to be fitted in the cylinders but so have the slidebars. I suggest now is a good time to make them and make sure they fit through the square holes in the cylinder ends.

The slidebars come in two parts. To make them, I carefully clamped them together, fluxed and applied small amounts of solder to the edges so that the solder was taken in between the layers by capillary action. The top slidebars have two projections with a half-etched line. The half etches go inside as they will take a rod later.

top-slidebar_3427crw.jpg

The bottom slidebar has been soldered but not cleaned up. The top slidebar has has the etching cusps filed off, polished with micro mesh and the holes cleaned out with a 0.35mm drill. The left end goes in to the cylinder, the right attaches to the G iron.

I found that the slidebars fitted the holes if the etching cusps were removed, a tricky operation unless you have a very small file. The one in the image is an escapement file, 0.9mm square at its largest. I bought this a few years ago from Eileens and I warn you now, the price is eye-watering but the file has been invaluable. It is particularly useful for cleaning out slots for coupling hooks.

slidebar_3440crw.jpg


file_3441crw.jpg

Every hole was checked with the slidebar, so I hope that when I come to assembling these parts, they will all go together without difficulty.

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David B
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Postby David B » Fri Feb 01, 2019 2:55 pm

Assembling the cylinders - first, make sure you have the right bits!

cylinder_3444crw.jpg

I managed to get two S4 parts and two for either EM or OO. The S4 ones are the shortest. Do check you have them all the same length.

You only need two of the parts with the rounded end, one for each side. These do need to be at right angles to the frame, so check measurements at the base and outside. I used a piece of brass tube to help with positioning and holding.

cylinder_3443crw.jpg

The tubing that comes with the kit is just under 1.6mm od; I have used my own 1.5mm od tubing.

The cylinder inners I soldered in place. Again, the brass tube helps to line bits up. Jeremy assembled his off the frames; I preferred to build on the frames.

cylinder_3450crw.jpg

The piston stem guides (4 plus one half-etch) went on to 1.5mm od brass tube. I only soldered from one side and cleaned up the other. No-one will see the back! Leave 1mm of tube protruding unless you follow me and insert a short piece of narrower tube.

The cylinder ends are handed with the small footstep slot on the outside and above the centre line. I opened the slot with a 10A scalpel blade and chamfered the tab on the footstep. The tab on the footstep goes towards the middle of the cylinder end. I found it easier to assemble these three bits off the tube, flat on the bench, tinning the cylinder ends and using the RSU. Getting the step in is an exercise in working out how to hold bits for soldering and getting the step square to the cylinder end. This was a challenge.

On the top tube in the image I have added a short (2 or 3mm) piece of 1mm od 0.5mm id tube. I spoke with Jeremy and we found the piston rod on the prototype is 2" in diameter which is about 0.65mm in 4mm scale. I prefer to understate and am using 0.5mm rod but you might prefer to use something a bit larger. Either way, there should be about 1mm of tube projecting from the stem guides.

cylinder_3452crw.jpg

I then did a dry run with the cylinder tube and the slidebars. This needed some fettling. Be very careful not to take too much out of the slots in the stem guides or you will have the slidebars too close together for the crosshead. It might be worth making the crosshead and checking the measurement. I will come to making the crosshead soon.

Lining up the stem guides and cylinder ends (the wire is just for the photo) . . .

cylinder_3454crw.jpg

. . . then the cylinder bits on the chassis . . .

cylinder_3455crw.jpg

. . . and fettling until the ends of the slidebars fit the slots behind the cylinder front across the front of the chassis.

cylinder_3457crw.jpg

Do not fix the slidebars yet but make sure you know which ones go where. You may need to make small adjustments later when when the G irons go on. However, do fix the tube in place. I did not find it necessary to solder the cylinder ends as I soldered the tube from the inside and solder flowed through to hold them. The excess tube at the front can be filed off.

This part of the construction takes some time and is fiddly, so be patient, use minimal amounts of solder and only make small adjustments when fettling.

CornCrake
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Re: Steam up

Postby CornCrake » Fri Feb 01, 2019 6:42 pm

HI David,
Thanks for posting your progress with the motor bogie. I am learning something new each post, and they make a useful complement to Jeremy's instructions.
Steve

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David B
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Re: Steam up

Postby David B » Fri Feb 01, 2019 7:58 pm

Thank you, Steve. Having made two or three of these in development and now working on a couple of the final product, I still make mistakes (like not matching the two bits of the cylinder ends and the footstep slot not lining up) and find it important to think a few moves ahead if I'm not to get myself in to more of a pickle. I hope the chronicle helps other modellers to avoid some of the pits I have fallen in to.

Inevitably, when re-reading the posts, I find I have omitted something. For example, I soldered the steps on the cylinder ends from the back and filed them flat. This made the job a bit more difficult but the end result neater. When fettling the slidebars, I filed more off the top of the end that goes in to the cylinder. The bottom (inside) needs to be flat but don't take too much off or the crosshead might be too tight. We will see when we come to fit it!

It is little things like this that need to be considered - what are the consequences of what I am doing at the time? Think ahead.

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David B
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Postby David B » Tue Feb 05, 2019 6:11 pm

The boiler base went on much as Jeremy has described with a couple of small differences in method.

The bases were formed round a brass bar, mine is 9.5mm diameter. Press it so that it is all curved, not just the middle bit.

boiler-base_3458.jpg

Jeremy shortened the tabs on his; I bent mine in so that they fitted the slots more easily and went right through. Whilst the main tab is bent inwards, I also bent the end rivet of the bottom band outwards so that the base fitted the side better . . .

boiler-base_3460.jpg

. . . and to get an even better fit, I filed the parts that butt fit the sides to taper them. I filed the lower bit as well as this helps a couple of steps further on. I use miniature needle files from Expo Tools which are cheap. When they wear out, I chuck them and use a new one.

boiler-base_3464.jpg

With the base slotted in place, by keeping pressure on from the outside the tabs fit positively and are easy to solder from the inside. The red block is moulding rubber which is a very poor conductor of heat, protecting your fingers. Moulds have a limited life as moulds, so here is a way of prolonging their use.

boiler-base_3465.jpg

The base in place.

boiler-base_3467.jpg

The finishing touch is the rivet strip across the top. There are two 'rivets' on the boiler base which are in fact location aids as there are two dimples in the back of the rivet strip. I tinned my strip but made sure the location parts were not obscured. I found it helpful to shape the strip before fixing in place, first by bending round the bar and then bending the 'wings' outwards. I tinned mine as I used resistance soldering to attach the strips.

boiler-rivets_3469.jpg

Finally the body spring mounts are folded, rivets pushed out and then soldered in to the half-etched squares. I found these needed a bit more than the etching cusp being taken off so that they sit down properly in their allotted place. Again, I tinned the parts and used my RSU.

Before putting these in, I also drilled (0.8mm) and tapped the holes 14BA. Going much further along the line, these mounts will be used to fix the suspension mounting plate. In Jeremy's instructions, this comes near the end after the valve gear and pick-ups. Jeremy uses 14BA bolts and nuts. By tapping these brackets now, I am hoping to avoid using the nuts. If it does not work, then I can drill the holes and follow Jeremy's instructions. Expo Tools do taps and drills, either separately or in sets, at reasonable prices. They could be useful for occasional use. Mine did not come from Expo so I can't speak as to their quality. My tap cost even less, £1 from a second hand tool shop.

spring-mounts_3476.jpg

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David B
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Postby David B » Thu Mar 14, 2019 2:24 pm

Now we come to the finer work, beginning with the Motion Bracket. There are a number of parts involved, so it would be a good idea to identify them.

The main bracket comes in 3 sizes - OO, EM and S4; the rest are universal. The edge parts which go inside, on top and below the G are on the valve gear etch; the reversing lever and expansion link bracket parts (at the bottom of the image) are on the main etch. The arrowed areas on the triangular top bracket edging are the parallel sections Jeremy refers to and face forwards. I found it easier to make the G bracket as a sub assembly before adding it to the chassis.

Motion-bracket_3478.jpg

I cleaned the half-etch with a 13thou slotting file. This is a Luthier's tools (a maker of stringed instruments). I bought mine individually from Stewmac in the US; there are other sources. The files come in a range of thicknesses from 10 to about 56thou and file only on the edge. The drawback is that the edges are rounded, not square. The tweezers are ceramic tipped from Ebay.

Motion-groove_3483.jpg

Shaping the liner for the G, I used a piece of 2mm rod and the 'edge' from a Hold'n'Fold. Do make sure that the half-etched line is on the outside - it somehow seems natural to have it on the inside in which case you will have to straighten it and begin again. I speak from experience.

Motion-liner_3496.jpg

Once shaped, I cleaned the inside of the G, chamfered the edges a little, then slotted in the liner. Beginning at one end, I held the. liner against the bracket and applied a small amount of solder. The liner is the exact length required, so do not leave an overlap. I then worked my way round the liner, shaping as I went and holding with the tweezers as I applied small amounts of solder (and flux, of course).

Motion-liner-stages.jpg

When complete, I cleaned up the solder with a small chisel I made from scrap etch. The one illustrated is a single thickness which I made too long and found a bit flimsy, so I made another, shorter, with a double thickness of etch. The chisel is about 1mm wide and soldered in to 2mm brass tube, which fits nicely in to a pin vice as a handle. Finally, I rubbed the edges of the liner on some wet and dry laid flat on the bench, to remove the etching cusps.

Motion-clean_3488.jpg

The top and bottom bracket edgings were added, soldering the back edge on then bending before soldering the front. I also folded the reversing lever bracket, which fits in the half-etched square at the bottom of the G bracket.

Motion-complete_3505.jpg

The expansion link bracket is made of two parts. With the Y piece held in a vice, I bent the bracket, fitted the Y piece in to the slot and soldered them together. Using a small steel drill bit through the holes helped to hold the bracket. In the image, I have not got the parts quite lined up, so they were adjusted.

Expansion_3503.jpg

I dry-fitted the slidebars and motion bracket, trimming the slide bars from the front (inside the cylinder) until the motion bracket fitted at right angles to the frame. Make sure Y piece of the expansion link bracket fits through the slot in the motion bracket before it is fitted to the chassis. I found a little tweaking was needed as the expansion link bracket fits very close to the slidebars. The motion bracket was soldered from the inside of the chassis and the slidebars were soldered with a small amount of solder where indicated, on the top and bottom surfaces where it was easier to clean up. I have yet to add the expansion link bracket.

Motion-in_3509.jpg


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