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Tools

Quartering tool

 

I have already written an article on the subject of quartering. If you may want to know more on the subject of quartering you may want to read that article first. In that particular article I also described a suitable jig to quarter wheels accurately. The setback of such a tool is that you need a different tool if the wheels are too much different from the one you originally designed the jig for. This is exactly what happened when I built my NBDS 119. I needed to quarter the wheels because I had taken the wheels off their axles to turn down the pizza cutter flanges to the RP25 norm. Consequently the quartering was bust. I tried to restore it by eye but failed to get a correct quartering. The quartering jig was not suitable and the wheels had no crankpins. So I needed to find a different solution that 1. could be constructed relatively easy and 2. could be more versatile.

I soldered two rails on a small sheet of 0.75 mm brass. I milled a gap of appr. 4.5 mm in them.

Using a mill is not necessary, I was just lazy, any modeler should be able to achieve the same result with accurate filing.

 

The axle will settle in the gap like this.

What is critical.

  • the rails should be spaced at your gauge of choice. 16.5 mm in my case.
  • the brass sheet should be 100% flat.
  • the gaps should be identical ± 0.1 mm and the centre line perpendicular to the rails

What is not critical.

  • the size of the sheet, as long as it wide enough to rest the alignment tool on the long side
  • The size of the gap, in my case it is 4.5 mm but 5 or 6 would be good too, provided the wheel flanges hang free at their lowest point. The width of the gap is a trade off. The wider the gap the more stable the wheels will settle. Too wide a gap will give problems with smaller wheels touching "the ground".

 

I also made an alignment tool from transparent styrene card.

Making the card

I first cut the bottom line with a fresh, sharp blade along a steel ruler ensuring an identical knife position all the way. I cut in multiple strokes. Do not be tempted to break the styrene sheet as you may be used while building houses. It will leave a rough edge, and you are aiming for a clean straight cut.

 

I checked the result for straightness against a ruler. If you hold it against a light source, any light spot betrays irregularities. The length of the sheet at this stage was oversized, I incidentally had a strip this long. The longer the sheet is the higher the accuracy you can achieve in getting top and bottom parallel. The downside is you have more waste.

 

I set out the top line with a Haff compass at approximately 35 mm, taking the bottom line as a datum to run one leg against it and using the other to make a scratch.
After cutting the top edge, the strip is checked with a caliper to be parallel. The difference of width of the card on the left and the right side should be less then 0.1 mm. I was spot on!

Using an engineer's square I drew the vertical line. I cut the top line along the steel ruler.

Perpendicularity of the vertical line should be checked with the engineer's square from both bottom and top side. There should be no noticeable difference.

Similar to the top line I drew the horizontal measurement lines, spacing them by 1 mm. The horizontal lines are in the lower half of the card, leaving the upper half blank. The blank side is easier to use when measuring on the vertical line. You can also opt for two separate cards, one with the vertical line and one with the horizontal lines, as many as you want and where ever you want.

Finally the length of the sheet is cut to a suitable size, in my case 7 cm.

On this photo at the far right you can see an earlier attempt on different material. I slipped twice, hence the two conspicuous diagonal scratches.

What is critical about this card?

  • The top and the bottom (long) side should be absolutely parallel. The card is turned around during measuring the quartering alignment so any deviation from parallel will introduce a measurement error.
  • The vertical line should be, as you can guess, exactly 90 degrees. Measure both from the top and the bottom and you should have no measurable difference.
  • The horizontal lines should absolutely horizontal.

What is not critical?

  • The exact length and width of the card. Although the size should be practical, it does not come down to tenths of mm's.
  • The left and right sides. They are vertical for aesthetics sake but perpendicularity is not critical.
  • The relative spacing of horizontal lines. Spacing is aimed at 1 mm and regular pacing is pleasing to the eye, but again no harm done if there is an extra tenth of a mm.

 

First the vertical line is used to align one side of the wheel set. The datum side should stand absolutely vertical.

After lining out one side carefully turn the whole brass plate with wheel around and measure the other side.

Well, this wheel is clearly out of quarter. Adjust and start the whole procedure again until you have a good result.

Costs of the tool, maybe $5. For me it cost nothing, I only used scraps I already had. Is the tool accurate? Well, good enough. It works and it works for many wheel sizes, albeit only for 16.5 mm gauge. But then again, if you need one for another gauge, it is cheap and quickly made.