I am a woodshop teacher. We have three kids and myself almost ready for layup. One real problem we face is having other interested kids handle materials. Kids don't look with their eyes only. Many students are interested which is great, but it will take a delam or two to make believers out of students. Here are my plans.
1. Base: Sand blast edges, bend, super glue and seal in plastic bags. Just before layup take base assembly out, acitone one day and then flame treat just before layup.
2. Core/Sidewall: Hand sand core and side wall with 80 grit and lightly flame treat edges.
3. Top Sheet: Acitone and then flame treat.
4. Lastly for allignment in our vacuum press I am thinking of using needle and dental floss with a close cut veneer top sheet. My side walls are only about 8 mm wide and any lateral movement will mess us up.
Thanks for all the help!
Best Practice for preping materials for layup.
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Hello Hadley,
Great that you have so many kids interested in building skis. Regarding their handling of materials, here are my thoughts.
First, the base and top sheet. The surface treatment that is done at the factory is really quite thin on the surface of the material and can be degraded pretty easily by too much handling and by contamination by things like skin oil. The skin oil and other contaminants can be removed by an acetone wipe-down prior to lay-up. I haven't seen (or read) any evidence that acetone degrades the dyne level of the surface treatment. I wear rubber gloves when I handle/machine the base and top sheet, just to be on the safe side. If the surface treatment gets worn or abraded away due to too much handling, that can be a problem (see below).
Regarding your plan to flame treat the base and top sheet just prior to lay-up, I definitely recommend against it. For one, getting adequate surface treatment on any material via flame treating without the proper equipment is a 'crap shoot' at best. Trying to flame treat UHMW that is as thin as the base and top sheet will end up in extensive material warping (and probably a fair amount of melting). The material comes from the factory with a good surface treatment and you'd probably only destroy it if you attempted to 'bump treat' the factory treatment. On this really thin material, the factory uses water cooled rollers to keep the material from getting too warm and they use full width burners to keep the surface treatment uniform across the width of the material.
On the steel edge, yes, definitely do a sand blast and acetone wipe-down prior to lay-up... and then only handle the steel edge while wearing rubber gloves. The acid present in skin oil can cause delayed corrosion of the steel, even weeks after lay-up.
Post some pics of the kids at work.
G-man
Great that you have so many kids interested in building skis. Regarding their handling of materials, here are my thoughts.
First, the base and top sheet. The surface treatment that is done at the factory is really quite thin on the surface of the material and can be degraded pretty easily by too much handling and by contamination by things like skin oil. The skin oil and other contaminants can be removed by an acetone wipe-down prior to lay-up. I haven't seen (or read) any evidence that acetone degrades the dyne level of the surface treatment. I wear rubber gloves when I handle/machine the base and top sheet, just to be on the safe side. If the surface treatment gets worn or abraded away due to too much handling, that can be a problem (see below).
Regarding your plan to flame treat the base and top sheet just prior to lay-up, I definitely recommend against it. For one, getting adequate surface treatment on any material via flame treating without the proper equipment is a 'crap shoot' at best. Trying to flame treat UHMW that is as thin as the base and top sheet will end up in extensive material warping (and probably a fair amount of melting). The material comes from the factory with a good surface treatment and you'd probably only destroy it if you attempted to 'bump treat' the factory treatment. On this really thin material, the factory uses water cooled rollers to keep the material from getting too warm and they use full width burners to keep the surface treatment uniform across the width of the material.
On the steel edge, yes, definitely do a sand blast and acetone wipe-down prior to lay-up... and then only handle the steel edge while wearing rubber gloves. The acid present in skin oil can cause delayed corrosion of the steel, even weeks after lay-up.
Post some pics of the kids at work.
G-man
Picture Upload Attempt
I don't quite get how to upload an image. I recognize the Img* button is part of the process. I am also interested to see if I can post my skis and the data sheet that you have in the ski gallary. I am really not a computer moron but I'm just playing one in this format. Thanks for the help so I can get up to speed.
Here's a link to the page where collin and hoseman taught me how to post pics. If I haven't posted a pic in awhile, I still refer back to it for a refresher.
http://www.skibuilders.com/phpBB2/viewt ... ight=#2020
G-man
http://www.skibuilders.com/phpBB2/viewt ... ight=#2020
G-man
I'll add to G-Man's post.
As a teacher I trust you are in a well ventilated area and wear the proper protective equipment. I do believe that the flame treatment is a crap shoot at best. But at this point what options do you have? I would give it a try and have a test piece so you can get a good idea of the speed you need to pass with (not too slow to burn or warp the material).
Cleanlyness is next to ....
Great that you nave the students interested in making a ski / board.
Alignment can be solved by using a standoff (?). These are used in electronic circuit boards. Tiny T nuts out of plastic. Drill the core, one in front and one behind the binding mounting areas. Put the nut in and align with the base. Fill the tnut with super glue. let set and remove the core. now you have indexing locators. Ask in you do not understand or need more information. Happy ski building!
rockaukum
As a teacher I trust you are in a well ventilated area and wear the proper protective equipment. I do believe that the flame treatment is a crap shoot at best. But at this point what options do you have? I would give it a try and have a test piece so you can get a good idea of the speed you need to pass with (not too slow to burn or warp the material).
Cleanlyness is next to ....
Great that you nave the students interested in making a ski / board.
Alignment can be solved by using a standoff (?). These are used in electronic circuit boards. Tiny T nuts out of plastic. Drill the core, one in front and one behind the binding mounting areas. Put the nut in and align with the base. Fill the tnut with super glue. let set and remove the core. now you have indexing locators. Ask in you do not understand or need more information. Happy ski building!
rockaukum
Picture Test
Here is a picture slide show I have.
First Pic Upload
Here is a picture of the first student that glued on a sidewall. He was pretty proud. Tomarrow after school we have a work session. I will take pics.
Hadley
Thanks for the help!!!
Hadley
Thanks for the help!!!
RA
Do you see the t-nut base projected onto the PTEX base on the pressed ski?
Do you make a recess in the core?
Is this the sort of standoff you use?
http://www.mcmaster.com/
Part# 91145A157
Do you see the t-nut base projected onto the PTEX base on the pressed ski?
Do you make a recess in the core?
Is this the sort of standoff you use?
http://www.mcmaster.com/
Part# 91145A157
Wheezer,
That is the one. I do not remember if I got the plastic or the PTFE(?) Either way they work great. Once glued into place you remove the core from the base. durring the layup you will have to either cut a slit in the glass to go over the standoff or just work the glass over it without cutting the glass. Make sure you get a size that will work with your ski core (not too tall or fat, but you can cut the excess off, what is above the core). Let me know if you have any other questions.
rockaukum
That is the one. I do not remember if I got the plastic or the PTFE(?) Either way they work great. Once glued into place you remove the core from the base. durring the layup you will have to either cut a slit in the glass to go over the standoff or just work the glass over it without cutting the glass. Make sure you get a size that will work with your ski core (not too tall or fat, but you can cut the excess off, what is above the core). Let me know if you have any other questions.
rockaukum