Has anyone built an ice level tool, to measure the dish in a sheet? How did you build it. Would be a neat tool to play around with.
OfflineHas anyone built an ice level tool, to measure the dish in a sheet? How did you build it. Would be a neat tool to play around with.
John Minnaar has one called a Positional Overhead Device [I think]. He will perhaps reply & describe it.
.. ... .. but why bother measuring the flaw? Just fix it! When you flood, if you flood deep enough for the water to find it's level before any part 'dries' [freezes], the sheet will be as 'level' as it is going to get. The job then becomes that of making it actually 'flat' since water never freezes without some slight deviations caused by draughts, differences in floor temp, depth of water etc.
Ice that has been 'flattened' will not stay that way for very long because it gets worn off by curling, sublimates, compacts etc.
'Flattening' can be done by repeated full scrapes; the whole sheet each time, until there are no more spots untouched by the blade. It can take several passes to get to this point but it is worth it. When scraping after a flood low spots usually show as 'dirty', with the whitish muck from the minerals that are squeezed to the surface as the [tap] water freezes. This 'dirt' is an excellent indicator of where the ice surface is still low. It's also the stuff that gets on people's clothes and brooms, and reduces the speed of your ice.
If you use purified water to flood the low spots will probably show as 'shiny', but the same principle applies.
Between floods the same technique can be used except that now the low spots will be shiny compared with the freshly cut surface which has a 'matt' [lightly frosted] finish.
If it's still shiny the blade hasn't got there yet... Keep scraping.
Of course this all depends on having a blade that is 'true' and well balanced; and using patterns that scrape the whole sheet each time.
Havanicedayea! Ian
I've always wondered how surveying equipment would work.
We call it the IcePOD, for Precision Overhead Device. The frame comes apart to fit into a travel case, three lengths of piping that slot together into triangular plates at the ends. Between the plates we tension a cable as tight as hell and level it by using Vodka and a plastic tube inside the top pipe (spirit level!). From the cable we hang a precision dial (within 0.01mm) that measures the level of the ice.
Sounds easy, but it was made by an engineering firm to be sure it is strong enough for the tension. It works very well, if it is used correctly it cannot lie. Mine cost a fortune, but you can make one for yourself that should cost less.
Surveying equipment is only level within 1mm, which isn't enough. Stone will find 0.1mm no bother.
Make a manual one. Use two rocks,one at each side of the sheet, run a colored fishing line under each rock and across the sheet. Place a coffee stir under the line beside each rock and pull the string tight. With a third stir stick check the gap made by the first two sticks. If there is no gap your sheet is high in between the rocks and if the stick slides under the string with room to spare you are dished. Your blade will also tell you if you are dished or high centered by the shape of the snow on the blade.
Glenn Albertson
Glenn, I love the idea, the concept is brilliant and we now have an understanding of what we're looking for.
Alas! the sag of the string will guarantee that you will think a dished sheet is level. But good strong fishing line would maybe get you close enough for curling. However, if you're happy with eyeballing a stir stick under a string, [on top of the pebble?] I'll have to keep that in mind.
I prefer to trust my blade to tell me if I have scraped enough.
As long as I can still see the bottoms of the dishes, I have not really finished the job. Have I?
When they're gone, I'm done.
As long as the blade is true... Ian
I've got a unique situation about sheet dishing. I do the same routine on all my 6 sheets five of them are dished and one is slightly crowned. I do the same routine on all my sheets for pebbling and scraping why would one crown while the rest dish? would it be my floor or something in the environment air flow?