what Tolerance?

[ggardner90]

I am building my planer jig or profiling and i am wondering what kind of tolerances that you guys are holding. i think that when it is all done i will be at +or- 0.27mm

do you think that it will be tight enough to make good cores on or should i figure something else out to get more precise?

also same question for the molds, what tolerances are you able to hold and what should my target tolerance be?

[jvangelder]

I wouldn't want to go much larger as far as tolerances is concerned. Are you making a router bridge or planer crib?

-Jacob

[ggardner90]

i am making a planer crib. do you think that it would be a better idea to do a router bridge? what tolerances are you able to hold on everything? i am looking for some goals to shoot for.

any ideas would help

[Richuk]

I'm happy with the planner method, but then I'm not using bamboo. Lots of designs to look at in the journal section, the adjustable slid designed by Falls has been followed quite a lot. I think SHIF gave this a lot of thought too. If you want to push past 0.27mm, then have a think about how you can use painters tape (0.1mm thick) and packaging tape (0.07mm) to refine (pack) the mold. Once you get to within +/- 0.07mm I would say you are there and it won't affect the work you are doing on flex prediction.

[Dr. Delam]

I find the planer crib method to be way more accurate and user friendly. Of course you have to start with a planer that is accurate but if everything is set up properly you should be within .05 mm of your target numbers.

[ggardner90]

thanks alot i will shoot for +or- .07 mm i like the painters tape and packaging tape ideas definitely going to use it

[twizzstyle]

The core profile, in my opinion, is the most important place to be accurate. Everywhere else - the mold, the sidecut, etc - you can have a small amount of error and you likely won't notice a difference on the slopes. The bending stiffness of the ski is proportional to the cube of the thickness. If you doubled the thickness along the entire length (extreme example), it would be 8 times stiffer!

.05mm shouldn't be hard to achieve using a planer and taking shallow cuts, I think I'm probably achieving that accuracy.

[SHIF]

The core profile, in my opinion, is the most important place to be accurate...

This is totally true. Using a digital caliper, I measure the thickness on both sides of the cores along the length of the ski at 10cm intervals and chart the data. Then I make subtle adjustments where required using my belt sander, and measure again. It takes a few iterations to dial-in near prefection. Time spent making accurate cores will result in really great skis. Sloppy cores will not perform as desired.

I'm using the planer bridge method to create the basic tapers then scooping out material to create the thin, parallel profiled tip and tail zones using my big old belt sander with 40 grit. This is slower than the planer crib approach but my planer is too light to handle that work load. After making several pairs of skis I have the technique down. Of course my method is totally unacceptable for production but fine for the garage hobbyist ski builds.

-S

[skidesmond]

The core profile, in my opinion, is the most important place to be accurate...

This is totally true. Using a digital caliper, I measure the thickness on both sides of the cores along the length of the ski at 10cm intervals and chart the data. Then I make subtle adjustments where required using my belt sander, and measure again. It takes a few iterations to dial-in near prefection. Time spent making accurate cores will result in really great skis. Sloppy cores will not perform as desired.
.....
-S

So true, digital calipers are a must to get it dialed in. Worth the $35-$40. make sure it reads out in inches and MM. I use a planer crib and still need to tweak w/ a belt sander a little bit.