Rough Core - Profiling Problems

skiingfreak · Post by **skiingfreak** » Mon Apr 07, 2008 9:09 pm

We started to profile our cores recently and ran into a few problems. The main issue was that the core seems to want to suck up into the router while we're profiling. At first I thought this was the router sliding down from its locked position, until I switched to another router and a new bit, I noticed that the wood is definately sucking up from our profiler table. I'm not too worried about saving the core because I think i can either use veneer or patch up the mistakes, but this also seems to be making a rough surface.
To try and remedy this, we went ahead and started driving in screws in the area near where we have been routing the cores, but we are still ending up with some ridges. This does resolve the major suck up problem though. Do people generally just sand out ridges like these or are we doing something wrong? I'm fine with doing the work sanding, but I haven't seen any core pictures up here that look this rough.
Here are a couple pictures:
http://picasaweb.google.com/skiingfreak ... 7318098050
http://picasaweb.google.com/skiingfreak ... 8728163442
Thanks for any help in advance!

MartinJern · Post by **MartinJern** » Tue Apr 08, 2008 2:14 am

Before I started profiling with a planer I had the same problem as u.
To prevent the core from rising up to the router I ended up with a method that worked for me.

I made it in 2 stages, first i shaved off half of it, then i taped it down to the table with double sided tape. this will hold the core down now that it is thin and softer.

hopefully this will help...

sammer · Post by **sammer** » Tue Apr 08, 2008 5:12 am

Having just finished my first core night before last, I can suggest using hot glue
Just a few spots around the edges of your core and tip and tail
worked awesome and I'm making skis for my kid, tips are just a hair over 1mm!
sam

jono · Post by **jono** » Tue Apr 08, 2008 5:56 am

Hot glue is the way to go.
It was sad to see the wounds on your beautiful cores.
I've had good luck reprofiling cores after I filled my own wounds with veneer.
Good luck!!

skiingfreak · Post by **skiingfreak** » Tue Apr 08, 2008 2:42 pm

Perfect. Thanks for the replies. I thought about using a little bit of wood glue but that seemed a little too permanent. It sounds like hot glue is the way to go. Thanks for the feedback!

G-man · Post by **G-man** » Tue Apr 08, 2008 7:37 pm

I use a vacuum profiler and I'm pretty sold on the method. There's no way to pry a core blank off the table when the vacuum is on, but when I turn the vacuum off, the core lifts right up... no risk of breaking the thin core sections like there is with hot glue.

G-man

skiingfreak · Post by **skiingfreak** » Tue Apr 08, 2008 9:37 pm

So what's the setup look like for a vacuum profiler? Do you have something that slides along as you go over that spot? Or do you just basically have a kind of trench that runs the length of the core?
Do you mind putting up a couple of pictures or explaining in a little more detail?
Thanks!

skiingfreak · Post by **skiingfreak** » Tue Apr 08, 2008 9:58 pm

Nevermind, I just found your post that has some details. I'd still be interested in seeing a few photos if you have them available.
If anyone else is interested, i found the post here: http://www.skibuilders.com/phpBB2/viewt ... m+profiler

thetradwoodboat · Post by **thetradwoodboat** » Wed Apr 09, 2008 3:17 am

i'm also using a vacuum setup under my core profiler, works great. here's a brief description i posted last year;
i'm using a router bridge type profiler like as most guys are. underneath the deck of the profile jig i built a shallow box the same area as the deck. i then drilled holes in the deck ( about 1" dia.)that would be hidden by the core stock when it is in place on the jig. a bigger hole in the bottom of the shallow box accepts the hose from my dust collector. when i switch it on there is an amazing suction created on the core stock, it holds it perfectly flat. i've had to hot glue locators on the deck to keep the core from sliding slightly during routing, but otherwise it is great! i would guess it would still work well with a shop vac.

G-man · Post by **G-man** » Wed Apr 09, 2008 7:42 am

My set-up is very much like what thetradwoodboat describes, except that I use a shop vac. Also, I use a fairly soft foam tape (about 3/8 inch wide and 1/16 thick) that is 'let-in' to the top surface of the profiler (forms a seal just inside the perimeter of the core). This tape seals any vacuum leaks and helps to keep the core from moving around. I've tried to push the core around with the vacuum applied, and I can't move it. Instead of drilling holes in the top surface, I routed 1/4 inch wide slots... don't know if it makes a significant difference. The vacuum if strong enough that, if the holes are too big at the thinner sections at the tip and tail, the core can actually suck a bit down into the hole.

I'll try to get to the shop in a few days and get some pictures. I'm still working at home trying to get this CNC machine on line, so I haven't been in the ski shop much (about 10 miles away). Made some cuts in the air with the CNC yesterday. That was fun, but I still have a lot of software learnin' to do.

G-man

kelvin · Post by **kelvin** » Wed Apr 09, 2008 10:51 am

Lots of good suggestion in the above replies. I would also add:

make sure your router bridge is very rigid. Even a little flex will cause the cores to be uneven.

Cut less material per pass.

It looks like your router is 'walking' in one of your pics. Make sure you cut against the rotation of the bit. Here is an article: http://www.newwoodworker.com/rtrfeeddir.html

I usually go side-to-side for the roughing passes and go lengthwise down the entire core for the the finishing pass. Finishing pass should be a very light cut, 1/16" or so.

-kelvin

skiingfreak · Post by **skiingfreak** » Wed Apr 09, 2008 1:50 pm

Thanks for posting that site. I really haven't done any reading about using the router since it seems like such a basic tool (I know, unsafe assumption).
So it sounds like i've been doing a few things wrong.
1. I need to do a better job of keeping my core down it sounds like the best options are tape, glue and vacuum. I'm going to give it a shot with some hot glue this weekend since it's readily available and won't slow me down much.
2. I'm removing too much material with each pass. I'm going to try and cut off about half as much material in each pass and see how much better that works.
3. I should make a point of routing both side to side, and front to back to keep things nice and smooth.
How many passes do most of you make when you're routing? Do you generally do it in 2 passes or do you end up making a 3rd pass in the end to keep it nice and smooth?

G-man · Post by **G-man** » Wed Apr 09, 2008 6:50 pm

I make about five passes... about 2mm each. Each pass takes about one minute. As Kelvin indicated, the last pass should only be about a mm, or so... sometimes even a half mm. I have 12 routers, so I can set up two or three of them on bridges. That way, if I'm doing a few cores on the vacuum profiler, the last couple of passes with the dedicated routers result in cores that are exactly the same thickness. As I've indicated before, it takes less than 5 minutes to profile a perfect core on my profiler. It's hard to beat that time even with a CNC machine. I only run the bridge lengthwise on the core.

G-man

Wannabebuilder · Post by **Wannabebuilder** » Thu Apr 10, 2008 10:19 pm

G-man wrote:I have 12 routers

OMG!

Send me one please?

sammer · Post by **sammer** » Fri Apr 11, 2008 4:08 pm

g-man, what size cutter are you using?

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Rough Core - Profiling Problems

Rough Core - Profiling Problems