I've got denting-Advanced Help Needed?

skidesmond · Post by **skidesmond** » Tue Aug 23, 2011 4:56 am

Ok now I'm getting the picture.

falls - (single vertical support) many of the vids I've seen from the big manufacturers use I-beam style of presses. And many in the forum have that style too. I have a center support, I'll re-check my stuff.

What about cores?? Could the problem start there? If the planer crib has any imperfections it could stem from that. My first planer crib wasn't a very precise piece of equipment and I noticed some waviness, mostly along the top, not so much on the base.

MontuckyMadman · Post by **MontuckyMadman** » Tue Aug 23, 2011 3:47 pm

the sleds we have are pretty accurate.
CNCed.
the tail denting could have been from the previous molds that were less accurate.
Also the tail denting may line up with the vertical support there but then we would have deflection and denting in the middle but we didn't then.
We have deflection but it is nominal and doesn't really affect the camber at all.
At 65 the center support does have less slack and is under load slightly.
The most recent cores we did were through the giant door sander and they were pretty perfect.

falls · Post by **falls** » Tue Aug 23, 2011 5:04 pm

falls - (single vertical support) many of the vids I've seen from the big manufacturers use I-beam style of presses. And many in the forum have that style too. I have a center support, I'll re-check my stuff.

There was a recent post I think of a video at maybe ELAN that had showed they had a lot of the "cage" style presses (like mine/mongo/benmtl/kingswood etc).
The other thing I possibly thought was in the I beam style presses they might be using the Langzauner type press where they designate the camber with multiple adjustable supports underneath a thick pressing plate. If you are seeing miniscule wave like denting on production models then the very high pressures could be translating these "strong" spots even through a plate of al/steel.
Not in any way saying I am right about this, but I feel that I saw it occur in my skis after I started pressing at higher pressure (65 vs 45PSI).

The other thing MM with multiple vertical supports is that if they aren't all exactly as long as each other then you could get variable amounts of deflection at different points along the press (?)

Cadman · Post by **Cadman** » Thu Sep 08, 2011 7:18 pm

I would think that this is a typical grinding issue caused from a stone that has not been kept clean. Little bits of grit get caught up in the stone and
create a "bump" in the stone. I good way to prove it out would be to change your feed speeds and see if the "dent" pattern changes. I bet it will change. Most companies live with this since dressing the stone more often will wear out the stone faster. Call Wintersteiger and ask them what they think. I bet they will tell you the same. Hope this helps you.

MontuckyMadman · Post by **MontuckyMadman** » Thu Sep 08, 2011 7:42 pm

this is straight out of the press, no grind.
I virtually never have a stone grind on my own stuff.

I have a base grinder with a autofeed but the denting does not remove without focusing on those areas to attempt to mellow the visual effect.

It's very hard to see and if you read all that I posted you will see its not a base dent its a full dent edge and all, its a laminate issue.

We will back the pressure down change the center topmold expansion blocks to sheet goods and try again.

I think falls nailed it.

The worst ones on the shop floor are the 4frnts and they are made at the Slovenian elan factory where they have all the cage presses, just like his.
Prolly over cranking the pressure at that factory to reduce press time.

Cadman · Post by **Cadman** » Fri Sep 09, 2011 3:12 pm

Hmm, I guess that I am out to lunch here then. I did not carefully read that it was right out of the press. I am intrigued now as to what you are seeing in the 4frnt skis. Which models of 4FRNT skis did you see the dents? Elan builds all but the Renegade in Slovenia. The Renegade is built in Salt Lake. I have seen the press in Salt Lake and it has 1 inch square bolster tubes over the length of the ski. Since the tube would contact the top sheet on the tip and tail at the outside edge and along the camber, I would guess it would contact in the center of the tube so just guessing here that the tip and tails would show the most faceting. Do you see this happening? Pressure definately could play a part in this. Getting enough pressure at the tip and tail is a problem on sharper radii so that is why you see presses with air cylinders added in the tip/tail area. If you turn the pressure up too much to try to get the tip and tails to press all the way, I would think that you may get too much in the center causing your resin-to_glass ratio to be off which could cause delamination due to dry glass.

falls · Post by **falls** » Fri Sep 09, 2011 4:56 pm

My last pair was the same MM with the waviness. Pressed at 65PSI in the bags. I think in my case it is the vertical supports
I think my plan with the new molds I'll get cut soon is to reduce the gap to slide the cassette in and better offset the top mold from the bottom mold.
I'm really only pressing at 65 because when I started using the 1.5mm aluminium for bottom cassette layer I needed way more pressure to get the tip to press in well. I hope with the new molds I can get a good press at a lower PSi (say 45?).

doughboyshredder · Post by **doughboyshredder** » Fri Sep 09, 2011 5:31 pm

could this be caused by the cat track? If your top mold sheet, plus blanket, etc... isn't thick enough, it may be allowing the cat track to create a pressure point which could be transferring through the laminate. Also, this could be being caused by the cat track separating a little bit, causing an area with pressure variances, which could also be transferred through the laminate.

falls · Post by **falls** » Fri Sep 09, 2011 7:48 pm

thats a good point doughboy. i was thinking about that this morning too.

MontuckyMadman · Post by **MontuckyMadman** » Fri Sep 09, 2011 8:53 pm

Ive got big springs. the cattrack stays pretty tight but Ill check it out.
Thanks

Cadman · Post by **Cadman** » Mon Sep 12, 2011 11:34 am

Bolster tubes and catrack are the same thing. I would be curious to see
if the faceting that you see on the base is more pronounced at the tip and tail or in the center of the ski.

MontuckyMadman · Post by **MontuckyMadman** » Mon Sep 12, 2011 1:41 pm

its only one place after we cnced everything right in the middle and lines up with the center support.
Bolster tubes and cattrack same? huh, I though he was referring to adjustable camber supports.

Cadman · Post by **Cadman** » Wed Sep 14, 2011 11:20 am

MontuckyMadman wrote: Bolster tubes and cattrack same? huh, I though he was referring to adjustable camber supports.

On the factory presses, they have adjustable bars about every 3 inches under the bottom formblock plate. I can see where that could cause some
faceting since these bars contact the formblock plate in a small contact area. Send me your email and I can send you a picture if you like.
Can you also tell me if you saw the flaws in the production skis that Elan was building or the ones that are being made in Salt Lake ( The Renegades)

MontuckyMadman · Post by **MontuckyMadman** » Wed Sep 14, 2011 12:46 pm

elan 4frnts from slovenia factory. I have never looked at details on the rens as I have only seen 1 pair as they are only available in very limited qty and distribution.

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I've got denting-Advanced Help Needed?

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