Tuning question - Base bevel

[Sidehill]

I recently asked our local shop whether their new $40K tuning machine could do a base bevel, and was told only the edge should be beveled.
All other shops I have asked over the years say the same.

30 years ago I worked at the Copper Mountain repair shop, where we often tuned skis for racers.  Our shop was taught a base beveling technique where both the edge and the base were beveled one degrees, so that the file actually beveled both the base and the edge about 1/4 inch in from the edge.  A shop in Frisco, which only did ski tuning, primarily for racers, taught us this technique.  The angle is achieved by wrapping duct tape around the end of a panzer file. I also side bevel 1 degree to keep the edge at 90 deg.

I have used this technique on all of my skis since and find that the ski is more forgiving, and that I feel stabler at higher speeds. Also, there is then little need to detune the tips and tails.

I'm just wondering if this tuning technique was used elsewhere 30 years ago and whether it is still in use today. It sure works for me.

[midwif]

Welcome Sidehill to RS.

There are a few "self tuners' on this forum so hopefully they will chime in.
I've been trained to say at the shop" A 1 and 3 please".

However, I am curious. Is the shop in Frisco you refer to Precision Ski??
After Harald Harb recommended them, Jim and I always bring our skis there for tuning
when in that neck of the woods.

They do seem to know what they are doing and we have had good outcomes there.
And have had some pretty terrible tunes at some shops in vermont.

Lynn

[jbotti]

Sidehill, I am not sure what the shop guy is talking about. Maybe that their machine is not meant for base grinding? Every ski after significant use requires base grinding and the base bevel on the skis increases as the metal gets worn down from use (so a ski that leaves the factory with a 1* degree base bevel after 50-75 ski days will be more like 1.5 or even close to 2. Base high is what we call a ski where this occurs. The only way to get back to 1* is to grind down the base, thereby reducing the base bevel on the metal. Most places will grind a ski to flat and then file the metal to the desired bevel angle by hand using a base bevel guide.

[LivingProof]

Digging deep back into the memory bank......

My very first memory of what is now base beveling was as stated by Sidehill, and, it was shown in either ski or Skiing mag as a "racer secret" to make edge changes quicker. Put two wraps of tape around a flat file, put the tape side over one edge and the other was slightly beveled. I can't recall if this produced a 1/4" wide grind of the base.

To be clear, this was not done by a grinding machine, which only got the ski back to flat.
Today, there are dedicated tools replacing the tape, and, for sure, they do not cut back the side edge to the point where it removes the polymer base.

Edit:
I remembered an Epic post that included CAD drawings to show the amount of material removed in base beveling...find it here. Interesting for technicrats, all others, have a good cup of coffee.

http://www.epicski.com/t/49730/base-grind-needed-or-not-for-small-change

[Svend]

Sidehill:  I agree with Max and the others.  No ski should be tuned flat on the base.  The skis will behave terribly on the slopes -- edges hooking and grabbing, edge-to-edge transitions unpredictable and poorly controlled.  I have rented or demoed skis that were tuned flat, and fought them all day -- some of the worst ski days I have had, and not because of weather or poor snow, just a really crappy tune.  I was exhausted after only half a day.

A 1 degree base bevel is used for most recreational skis, and is what I put on all the skis in our household, no matter their purpose -- soft snow or hard.  Further, the comment about filing a 1/4 inch in from the edge is just wrong.  You should never file more than JUST the metal edge when base filing, and once the base bevel is set with a chrome file (using a high quality file guide!), subsequent sharpening is just a light touch-up with a diamond stone to file as little as possible from the base edge (the real sharpening work is done on the side edge).  When I set the base bevel on a new pair of skis, a trick I use to make sure I don't take off too much, is to run a black felt marker along the steel, and then CAREFULLY file just enough until all the marker colour is gone, never more, and never into the P-tex base.

Side bevels are optional, depending on where you ski, how aggressive an edge you want, and your tolerance for grippy edges.  General guidelines:  1 degree side edge is what some people use for powder/soft snow skis; 2 degrees is all-purpose; 3 degrees for hard snow high performance skis.

For ALL filing or sharpening work you must use high quality bevel guides to get good results.  They really are worth the investment - I have never regretted buying decent tools, for skis or any other work, for that matter, and they pay for themselves in short order.  Swix, Toko, KUU, Holmenkol, SVST, are some of the makers of good tools and vices.  If you visit their websites, you will find good how-to guides for sharpening.  Swix has videos, too.  Some shops publish such guides on their sites too -- Slidewright is a good place to check out.

BTW, $40K may sound impressive for a tuning machine, but it really isn't.  A serious shop will have a Wintersteiger or Montana (both German or Swiss made), laser guided machine with ceramic stones that grind the bases flat, set side and edge bevels, and can be programmed to put whatever bevel angles you want, and whatever base pattern you want.  These cost at least $250K or more.  The quality of their tunes is remarkable (in the hands of a good technician in a reputable shop), and very accurate.  Go find such a shop, and ask some pointed questions of their tech about their capabilities. 

Hope this helps, but post back if you have more questions.  Glad to help.

Cheers, and welcome to our forum.

[Sidehill]

Thank you all  for your input.

I think the shop in Frisco that taught us this method may have been Precision Ski, but I can't say for certain.  However I did just call them and the tech said that they had been there since 1981 so it was probably the same shop.  The tech (who had been there 15 years) also said that they no longer beveled the base ptex along with the base edge; they now bevel only the base edge.

However, because of that phone call, and the post above by LivingProof, I'm gonna call it a win,  since the folks on the epic ski forum apparently think that I am absolutely insane for even considering such a thing as beveling the ptex base along with the edge.

I can testify that I still do it and it still works on a cambered ski, such as my Recons.

Thanks again

[beastieboy]

Two thumbs up for Svend.  Great post.  The only thing I could correct is his spelling of the word 'colour'.

[Svend]

Hey, ya gotta cut me some slack there Beastie.  Being Canadian, that's how we spell it.  You know, the proper way.....      Like neighbour, flavour, odour...I could go on and on.....

Cheers,
Svend

[jbotti]

"Most places will grind a ski to flat and then file the metal to the desired bevel angle by hand using a base bevel guide.'

I beleive I have been misunderstood. There are two ways to get to the desired bevel angle on a base (somewhere between .5 and 1.00 degree). You can either have the machine put it on at the desired angle or grind the ski to flat and then use file to bring it to the desired angle. Good technicians will grind it to flat and put the desired angle on by hand. If you don't have a good tech to do it, better to have the machine do it.

[LivingProof]

Let me rejoin the fray, and, once again, show off my YEARS of acquired wisdom (or foolery).

Back to the OP's questions. Eons ago, when we used skinny skis with a lot of camber, they were just flat filed. Then, sometime in the early-mid 70's, a major ski magazine did an article by a leading American skier who showed how he filed skis to produce a base bevel. I believe the pictures did show that bevel extended into the base by about 1/4 inch. It was all done by hand, after a full flat base grind. The benefit of the bevel was it permitted faster, cleaner edge changes and with really long skis that was an advantage because it took a lot to the old style on edges.

The downside is that you take off base material and will shorten the life if skis are ground flat again.

That was then and I can't see much value in continuing that type of bevel with today's skis. For sure, if it's not being done by World Cup skiers, there is no longer a benefit. I would never remove base material and possibly screw up a world class ski. Maybe someone could try it on today's rock skis. Put it on one edge only and then do a report out on what is the difference.

BTW, I got quoted by the OP in an Epic thread (anonymously - thank god) for my remembrances. I really do prefer today's technology over the 70's era. But still put wax on with on old clothes iron!

[Svend]

"Most places will grind a ski to flat and then file the metal to the desired bevel angle by hand using a base bevel guide.'

I beleive I have been misunderstood. There are two ways to get to the desired bevel angle on a base (somewhere between .5 and 1.00 degree). You can either have the machine put it on at the desired angle or grind the ski to flat and then use file to bring it to the desired angle. Good technicians will grind it to flat and put the desired angle on by hand. If you don't have a good tech to do it, better to have the machine do it.

Gotcha.  And you're quite right in that a good base grind, flat, structured, followed by a hand tune to bevel the edges can also give an excellent tune if done well.  The $250K laser machines poorly calibrated and/or in the hands of a poor tech will give a worse tune than a simple flat grind followed by a hand tune done by a skilled tech.  Pays to know which shops do a good job, using either method.  I didn't mean to make it sound like the laser machine was the only way to get a quality tune.

[Gary]

Probably like some  here that do their own tuning...I've had brand new skis come with bizarre edge issues.

AND even when I've HAD to have a machine touch my edges....I always put my guides back on them with a fine file and ceramic stone....I figure since I'm skiing them....I trust me!

G

[jbotti]

"For sure, if it's not being done by World Cup skiers"

WC skies pertty much all come from the factory with a flat base grind and guys like Willie Wiltz and other top technicians put on the desired base bevel angle. They also spend hours on each ski sanding it with paper getting the edges as smooth as posible.