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Tool for skrawking gutters


On nearly all buildings of my new layout there are gutters of the common type of semi-circular Zinc cylinders. On the first smaller building I did produce this from normal rectangular strip made into a half circle by scraping with a scraperboard knife and sanding. However as the amount of gutters on the set of buildings is nearing about a metre length in total, I felt that some faster method would be useful. I therefore produced a small specialised skrawker tool for the production of gutters. The whole affair is made from 0.5 mm steel packaging strip, the same free stuff as used for coupling rods. The tool consists of a piece of flat steel that is mounted into a small style aluminium X-acto knife handle. In this keeper there are two toolbits mounted, the first one for skrawking the underside into a half circle with a flat for glueing it to the roof. The second toolbit for scraping the top into a hollow curve. The toolbits are mounted at angle of about 20 degrees to the vertical to assist easier handling. The first toolbit can also be used for making half circular strip.


The photos show how the tool looks. The first toolbit is 2.7mm wide consisting of a 1 mm shoulder, 1.2 mm gutter and 0.5 mm guide for following the edge of the card. This bit is made by drilling a hole of 1.2 mm into the steel strip 1.6 mm x 1.1 from a square corner on the strip. The part is then clamped into the vice using a 0.6 mm drill to get the centerline of the opening exact in line with the top of the vice. Then use a file to remove one of the corners to open out the hole. Use a piercing saw to part the bit from the rest of the strip by cutting a rectangle 2.7 wide and about 5 long. The other bit is just a finger of 0.8 mm width, filed round at the top, with a bit more flesh for soldering at the other end. A rectangle of 2 x 5 mm suffices. The bits are mounted in 0.5 mm wide slots that are cut into the hammerhead with a piercing saw. The part for clamping the piece into the knife handle needs to be about 6mm wide. The size of the rest is not critical. I used the full width of the strip, which in my case is 12.5 mm. The slots are cut with the piercing saw, in this case a coarse one such as #0. To widen out the slot to a 0.5 mm just cut again but this time with the piercing saw kept at an angle. That way there is no need for a bar file. The sawblade is normally higher than it is wide and that can be used to good effect. Soldering the toolbits is with normal low melt solder after a thorough cleaning with abrasive of the surfaces to remove any blackening. The last thing is to sharpen the bits into a skrawker. To create a cutting edge the back of the bits is filed. This is easier after soldering when you can hold the tool. The standing time of edges will not be very long but more than a metre thus enough for my purpose, apart from that it can be easily sharpened again.

Using the skrawker is easy. Just position two sheets of 1 or 0.8 mm thick plasticard with a straight edge on top of each other. The lower one is just to raise the top sheet a little bit to prevent deep gashes into your cutting board. Make light cuts into the plastic leaving nice curls until you are left with a nice half round ridge. Turn the lot around and use a straight edge to deepen out the gutter. I didn't find it necessary to solder a depth stop to the toolbit but that is a possibility you may wish to do yourself. Final touch maybe some sanding with a strip of plasticard with some sanding paper stuck to it. This is another great tool for plastic: Glue number 240 dry cut with double sided tape onto a piece of 10 mm width, a length of 15 cm suffices. Best works some thick sheet of 1.5 to 2 mm for the right flexibility/rigidity . After finishing the freshly made gutter is parted from the sheet with a normal straight skrawker or sharp knife.

Side view of the complete tool and a piece of gutter (difficult to get on the photo!).

The two toolbits, left for the underside, right for the top of the gutter.

copyright: Henk Oversloot
date: 4 january 2004