It is almost 2014 and i yet to build a pair of skis for the season!!! Like usual i have been working on airplanes all summer and little bit of ski tooling.
The CNC is a way bigger project and learning curve then i could have imagined. When i purchased this old shopbot i upgraded it with a G540 so i could run it on my XP machine. This summer i went from 28Volts to 36V, added an Ethernet smooth stepper, vacuum hold down section. Now i can run on my windows 7 laptop. Much better. Still battling CAD, CAM MACH software. It only gets better with mistakes. Seriously is it possible to learn anything on a CNC machine without destroying something?
My vacuum table works amazing. I built a twiz style drag knife and let me tell you it works SWEET!!!! I spent about 10 minuets with my grinder and an old 1/4" drill bit and wala. Drag knife baby. Getting rid of all that router teeny tiny little base material that clings to everything in the shop was a happy day. Thanks for that great idea twiz.
Next i decided to do full wrap edges. The only reason being i can figure out how to draw the step for 3/4 wrap edges on cad. ARG!!! Of course this means more TOOLING. I build the nipper benders. They really do work amazing and take no time to build.
I have profiled some cores on the CNC as well. It is really cool to draw up a core and just push enter.
Thats it so far. I have materials on their way and hope to press this weekend but most likely next. As usual thanks for all the help builders.
Which CAD software are you using? I'm sure I can help you with that 3/4 wrap. Btw, how do you guys account for the offset of the blade when creating the toolpath?
In order to account for the blade offset you have to make/use a script which adds corner action for sharp corners + modifies the curves following this principle : http://math.ucsd.edu/~ebender/87/bicycle.pdf
I have been using snowcad to generate the dxf then importing it to draftsight. I just cant seem to figure how to select just the portion i want move. I would love some advice.
As far as the drag knife. All i do is a standard profile cut out with a tool diameter of nothing. I dont do anything else special besides making sure the knife is oriented properly for the first cut.
it seems to do a fine job for just a simple base shape. Im sure it would not work if i was trying to do die cut letters or something for the base.
Snocad to Draftsight and the waist moved on me ... I found the issue once the template had been cut. It happened a while back, when Snocad was in question and Draftsight was relatively new.
As long as your radii are sufficiently large (like just doing a ski outline) you don't need to worry about offsets. The one time I did a multi-colored base, I just put a small filet on every corner so I wouldn't have to deal with it.
Great job on the drag knife and the nipper! Sometimes the cheap solutions are the best!
You may want to push the blade up in your chuck a bit more. With 1/4" you may be ok, I use a 1/8" diameter blade. One time I had it sticking out maybe an inch, and it snapped. Now I only have maybe 1/4" sticking out of the chuck, if that.
Finally got my skis made for the season. I upgraded my heat controller with dual controls. One for top and bottom. I need to do some programming of the bottom as it seems to over shoot by quite a bit. It was about $35 with the SSR. I hope i can get it to perform more like the Auber i have on the top. It also seems that even with top heat only the base ski temperature is going to be much hotter then the top?
Im pretty excited about this pair. They are %100 carbon, no fiberglass. I have yet to weigh them but they seem pretty light weight. The flex feels pretty typical to my 20oz triax glass skis so i think im close there. I hope to get them ground and mounted in the next few days.
Nice work! Maybe you can look at the P, I and D setting on your Auber controller and just copy them to your new controller. They should both have these settings somewhere.
What weight of carbon fiber did you use to replace the 20oz fiberglass (especially how much fiber weight do your fg and carbon have in each direction?)?
I have found that my top blanket is a lot easier to control due to the aluminium cat track heat sink effect. Once the cat track is warm it stabilizes the heat in the top ally sheet where as the bottom is much more sensitive and therefore harder to stay on the target temp.
This might seem ghetto but these days I just plug my blankets straight into the wall socket and turn them on or off as needed. I get better results that way.
our first "heat controller" worked really awesome till the TC bulb got crushed, plus we changed brands of blanket. After that, the 1200 dollar unit was nothing more than a glorified on/off switch that had to be babysitted and monitored with a pampered chef Oven temperature probe. This worked out for four years!
BH Thermal really hard timed us about getting a proper replacement for the temperature sensor, so we sent them off with a GFY and built our own controller that works decent.
Built my controller several yrs ago for about 200-250. Dual PID control with Main on/off and individually controlled on/off for top/bottom. Works like a charm and holds temp very accurately +\- 3 deg, as programmed, as long as I place my thermocouples well.
vinman- Speaking of well placed thermocouples where do you place yours?
It would be cool to sacrifice a probe and lay it up inside a ski. Get actual temp in the ski. I have one probe on top of the top alum sheet and the same on the bottom. Im wondering now with this last pair if the tips and tails do not get as hot.
Just finished a new pair. Controller worked perfectly. Found some odd settings on the bottom controller and fixed that. I also had a piece of welding rod stuck in the fuse holder that was grounding out...
