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View Full Version : Using a skin to keep parts from moving..



ed_lang
03-30-2006, 10:14 AM
I have been making some basic cutting boards on my Alpha96 and holding them via vacuum. I screw a 1/2" corian square to the MDF spoilboard and machine grooves into it. I then added gasket material around the outside. I then place a plexiglas panel on the corian and start my vac pump. I then cut the outside profile of my cutting board just into the surface of the plexi. I then run gasket material around the inside of the cut. Then I drill a hole thru the plexi and lay my cutting board blank on top. All works great as long as I have sanded smooth the bottom of the blank and the wood is flat and will not pass air thru it. I also cut other items just like this. I do like the ability to finish cut something and release the vac and remove the part(s).

Now I am thinking I will try out the leave a skin and sand the bottom till the parts are released idea.

My question is to those of you who use the skin method, what do you release your parts with? Knife, drum sander or wide belt sander? Why did you choose the method you are using? Is it working great or do you wish to or plan to change and if so to what?

Thanks a bunch.
Ed

gerald_d
03-30-2006, 10:33 AM
For items as large as cutting boards, we run them through a thicknesser planer. In fact, we use planks which are still rough-cut on the back - the first time that side is planed is when it does the release in the thicknesser.

jamesgilliam
03-30-2006, 10:54 AM
Ed, We have done some odd shapes and left a skin a couple of times. Have used a knife and a drum sander to release them. Only draw back with the sander is part size. They must be long enough to reach the outfeed roller otherwise they can twist or turn up and then you get a grove sanded into the part. I would not recommend the sander on plexi, it will scar up the skin side of the part.

mziegler
03-30-2006, 03:59 PM
Ed, for small parts an edge sander works real good to remove the skin. I also have used a drum sander and that is a very doable solution too. The trick is to nest the parts in a sheet with enough material surrounding the parts to push them thru the rollers. The downside is that my drum sander can only remove .006 to .010 in a pass. Generally I need to do 3 to 5 passes to remove the skin. Mark

watswood
03-30-2006, 09:05 PM
I cut alot of smaller parts out of a hardwood blank and often use the skin method. My parts are too fragil for a planer and too short for my sander, so I use a trim router chucked with a 1/4" downcut spiral with a pilot bearing at the end. This goes very fast and leaves a nice clean edge on the bottom. If you are profiling your edges such as with a 1/4" roundover bit, you can trim the parts out and profile your bottom edge in one step.

donchapman
03-31-2006, 08:49 AM
Ed,I got lost in your description.
Would you please post a photo or two.
Thanks

mnrite
03-31-2006, 09:02 AM
Eugene,
Where can I get a 1/4 downcut w/ a bearing, the smallest I find is a 3/8"

Thanks
Mike

lto
03-31-2006, 09:48 AM
Mike,

http://mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_solid.html . Number 5089, These work.

gerald_d
03-31-2006, 10:18 AM
I'm intrigued by the "flush & bevel" bits shown on the page linked above. They look like they can cut thin tabs. Anybody tried them?

lto
03-31-2006, 10:24 AM
Gerald,

We use these also, for some plastic cuts they tend to burn with the slightest pause in movement.

ed_lang
03-31-2006, 12:11 PM
Hi Don, Sure I will post a link to some pictures of my bot. The pictures you will want to look at are on the last few pages. The others are just random Shopbot things at the shop. My shop looks quite different now so enjoy looking around the entire site if you like.

Others too of course.

http://kc4ylx.smugmug.com/gallery/883595

beacon14
03-31-2006, 12:15 PM
here's (http://www.amanatool.com/bits/rc_1008.html) another option for routing and easing the edge in one pass. Scroll down to the "No File" router bit # 47150

mziegler
03-31-2006, 01:29 PM
Has anyone try the MLCS brass piloted bits. The pilot is only 5/32”. Do they work OK? Mark

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_brass.html

lto
03-31-2006, 02:20 PM
Mark,

We've used them, theres more friction than with a bearing but for some more detailed shapes it is the way to go.

donchapman
03-31-2006, 08:15 PM
Thanks, Ed.
Great photos!
Now I better understand what you described above re vac hold down.
I like the way you use the double clamps, too.

mikejohn
04-01-2006, 01:13 AM
Ed
your photos beg so many questions.
Would you object to this thread being hijacked to answer a multitude of such questions, or can you start a seperate thread that points to this link "http://kc4ylx.smugmug.com/gallery/883595", so that we can ask questions from there?

I sit here drooling at what I have seen.


............Mike

watswood
04-01-2006, 07:48 PM
Mike E., I use whiteside bits available here http://www.routerbits.com/cgi-routerbits/sr.cgi?1143938481_557+98 (http://www.routerbits.com/cgi-routerbits/sr.cgi?1143938481_557+98) and at Woodcraft. They also sell an 1/8" downcut with a brass bearing for tight spots( it's the only one I have seen like it).

ed_lang
04-01-2006, 10:37 PM
OK Mike. New thread will be started