Base grinding

For discussions related to designing and making ski/snowboard-building equipment, such as presses, core profilers, edge benders, etc.

Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp

Kalvis
Posts: 5
Joined: Thu Feb 13, 2014 10:35 pm

Base grinding

Post by Kalvis »

Hi,

as the base grinding machines (stone/sand belt) are quite expensive, I was wondering, has anyone tried hand belt sander? Maybe some water could be applied on the base while sanding. I believe the idea is the same as for base grinding machines only the hand tool is narrower.

Thanks!
pmg
Posts: 479
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg »

Hi,

unless you have a hand machine that is wider than the ski, forget it. Even then, the result would not be half as good as a good ski service does it.

You can do it to test if the ski works at all, but if it does, get it a proper grind.

So, why is the hand grind so much worse?

1) A good ski service does not only belt grind the skis, but stone grind them. The stone is dead flat, making the ski the same. The surface it produces is very plain, and a structure for avoiding water "sucking" the ski down is applied in the last pass.

2) You would have to do hours of work with a hand machine and use quite some belts. On the one hand, you want to get some material away to get the ski really flat (it never is), but you also want a nice surface. So you may not take a belt too coarse even at the start. And then finish the surface with a quite fine belt, otherwise the base is terribly hairy and does not glide well at all.

3) With the hand machine, its very easy to accidently grind some depression or egde into the base (or even worse in the edge) - no way to repair that.

4) As the amount of water you can use is limited, its very easy to burn the base.

In other words:
Try to find a ski service in your area that is interested in helping someone who builds his own ride. I work in a ski service, It takes me 15mins max to get my new skis a perfect base finish (Talking about a pair).

Cheers
Philipp
Kalvis
Posts: 5
Joined: Thu Feb 13, 2014 10:35 pm

Post by Kalvis »

Thank you, Philipp, for the comment!
As you mentioned, that you work in a ski service, may I ask you another question which might be interesting for other forum users as well.
What about sanding base locally after Ptex repair? Usually after using Ptex candles and scraping them off with metal scraper, there are still signs from ptexing (the base looks different- dripped area looks darker etc.). After professional ski service the damaged area looks almost as brand new. Where is the secret?
pmg
Posts: 479
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg »

Well,

first, we use a melting machine for the repair ptex. Works better than getting it to burn - no grime in the repair ptex and so on.

secondly, the base is re-grinded, that makes most of the difference. This also would make a big difference if you candle-repaired it first.

Sanding locally may help a bit, but nothing beats a fresh stone grind :)

And if the servicemen do it properly, it can be done quite some times. There are some ski services that grind the whole base away in less than 10 services (that sucks), we get above 20 if the ski doesn't look too bad. We do not use a robot, but grind by hand with an auto-feeder and no too much pressure. Like this, we only take away as much material as needed (Checking after every single grind).
Most robots are set to produce perfect results in one pass, so they take away a lot of material in order to have a clean looking base and sharp edges after one pass through the robot.
Kalvis
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Joined: Thu Feb 13, 2014 10:35 pm

Post by Kalvis »

Thanks! Yes indeed, I believe nothing beats professional stone grinding machine.
twizzstyle
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Location: Kenmore, Wa USA

Post by twizzstyle »

A short belt, and very little coolant, won't keep the plastic cool enough. The long belts on big machines carry away a lot more heat, and they're doused with coolant (not just water).
rnordell
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Post by rnordell »

I have thought of getting one of the ski visions base tools but have not pulled the trigger on it yet. Kalvis, you could get one and let us know how it works :) http://skivisions.us/
Kalvis
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Joined: Thu Feb 13, 2014 10:35 pm

Post by Kalvis »

Twizzstyle, thanks, this makes sense.

Well, rnordell, their products looks pretty interesting. I am just wondering which could be more universal for snowboard- base flattener or file base flattener. Maybe somone has experience with these products?
skidesmond
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Location: Western Mass, USA
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Post by skidesmond »

I've used a belt sander and a spray bottle on my own skis before I bought a ski grinder. A belt sander is better than nothing. You need to have a very light touch, but it's not the tool for the job.

Back in the day we used a 12inch mill file :D
RYM Experimentals
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Location: Fall City, Wa.
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Post by RYM Experimentals »

If it's just a proto, you can get away with a cheap belt sander and spray water after each pass with a bit of coolant mixed in. Better than nothing but its a pain in the arse so buck up the $25 and have your local shop hit it with their stone grinder. I have an old Grindrite now but I still take the good decks in for a stone grind to get them flat. You can get skis flat on a Grindrite but its really hard to get a board flat.

Go ahead and experiment if you plan to make more. If you do use a belt sander, you can knock the hairs down with a quick pass of a torch but be careful, you can also quickly delam a deck doing this. Don't get greedy.

Good luck.
www.rymexp.com
On the edge of control is a good place to be!
gozaimaas
Posts: 663
Joined: Fri Feb 10, 2012 4:17 am
Location: Nagano Japan

Post by gozaimaas »

The hardest part is convincing the ski tech he can take more than 4 passes off the bloody thing. Grind it man till its smooth!
Dtrain
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Location: Prince Rupert/Terrace B.C.

Post by Dtrain »

I'm no ski tech. I can grind right through to core in 5 minutes😝
gozaimaas
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Location: Nagano Japan

Post by gozaimaas »

I dropped off a heap of boards for base grinds, got the call to come and collect, when I got there they were stone ground before being fully flattened, one even still had bits of contact on the base near the nose.
IMO you have to stress to them that they are new boards which have never been ground therefore they can hit them a bit harder than normal.
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falls
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Location: Wangaratta, Australia

Post by falls »

Same deal for me too.
My usual place is great. But others don't grind the nose and leave epoxy on the base. I think as you say they are used to tuning stuff that is already flat and trying to maximise the life of the base.
I like when they say "that will come off with the next grind". I don't know about everyone else but in Australia for 80-120 dollars a grind I don't think many pairs of skis ever get their bases done again.
Don't wait up, I'm off to kill Summer....
pmg
Posts: 479
Joined: Sat Dec 01, 2012 8:59 am
Location: Sonthofen

Post by pmg »

falls wrote:in Australia for 80-120 dollars a grind
Damn I need to go there and open my own ski service. Dude thats expensive!
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