Cutting edge profile

[wwaldner]

Hello,
First time posting here. Just recently acquired a used ShopBot and am presently working on getting it set up. This forum has certainly been of great help in the steep learning curve. Thanks to all.

Anyway, I am trying to figure out a way to cut a edge profile similar to the attached picture. The profile would place a long round-over on the top and bottom edge of the board. The bit shown would enable me to cut the profile in two passes and would work, but I have a 2 HP spindle and can't run the 3/4 shank.

I was thinking that I would cut the top side, and flip the piece over in the same exact position and route the bottom with same profile. If need be, i could cut this out the shape with a mill bit and then apply the profile. I was hoping to cut the profile and the final shape of the board at the same time.

So, I would appreciate some ideas/tips/advice on
1. Any router bits that could cut the profile desired.
2. Techniques/methods to index and cut top and bottom pieces.

I could use some ideas on how to get the piece lined up when flipping it over. I am planning on have some kind of vacuum fixture to hold it in place.

Hopefully this all makes sense. I am basically trying to cut out a cutting board and apply a nice tapered rounded edge.

[adrianm]

To be honest it would be far easier and faster to apply the edge using a router table.

If you're using VCarve or Aspire there are a couple of tutorials/projects that give ideas on two sided machining.

http://support.vectric.com/tut-aspire-3d-techniques
http://www.vectric.com/cool-stuff/projects/2012/cool-cubes.html

[wwaldner]

I am sure I underestimate the difficulty of this. I have not even cut out my first piece yet. To start with, I will start with the cutouts and do the shaping on router.

My ultimate goal is to try and do as much of this on the CNC for repeat-ablity and consistency. I am shaping bird's-eye maple and the table router tends to tear and sometimes causes less then ideal results. I am hoping that I can figure out a routine on the CNC that will give me more predictable results. This I hope to achieve using climb cutting and less chatter introduced by human handling.

[scottp55]

Wayne, Will the finished blank have a rectangular (90 degree) edge on at least 3 sides to reference off of (flipping)? Rounded corners don't make a difference for what I'm thinking.

[wwaldner]

Attached is what I have in mind. The blank(in red) would have 3 index holes drilled by cnc as the first step. The index holes are shown in red.

After the index holes are drilled, I was thinking I could:
1. Use a 1/2 mill bit to cut the profile to half the material thickness.
2. Use profile round-over bit and follow same path as step 1 on top surface.
3. Flip piece and repeat steps 1 and 2.

This would all be sitting on a vacuum fixture with pins aligning the blank to the index holes.

I could be all backwards on this...like I said, I haven't cut my first piece yet.
wayne

[barrowj]

Wayne,

As long as the index holes are exact from left to right you would be good to flip it that way. Another way to it is to have one side and bottom against a fence of some sort so you could filp and secure it again. Either would work, I have done both. I have also profiled edges and the only thing to get right is your depth. Let us know how it works out.

Joe

[kra]

wayne,
i cut a similar edge profile but much thinner material on a regular basis using a raised jig just made slightly smaller than piece being cut (actually larger than piece being cut but a trough is cut for bit to run in in the jig)
i cut top and bottom at same time with 1 bit
i use alignments built into the jig to locate part then the alignments hinge out of the way for cutting

you can get shaper type cutters made to your profile with 1/2" shafts

[wwaldner]

Randy,
Thanks for the info. Just a couple clarifications. You cut the part to size first and then place it on your raised jig for profiling? Is your raised jig setup to vacuum hold down? I assume you just have a gasket around the jig with a vacuum hole in the middle sucking down the piece being profiled.

Do you know where I might be able to have a custom shaper cutter made. Do you have an approximate cost for this?

[hh_woodworking]

Here is a company that is good to work with and makes custom cutters. Cost you will have to call them and find out too many variables unknown. :

http://www.ballewsawandtool.com

[kra]

wayne
i cut approx 1/16" oversize and let the edge profile bit clean it up to exact size
my jig is just lightweight mdf with vac pulling strait thru from normal vac table
no special gaskets or anything
i do have edges and trough area sealed to prevent unnessary vac loss and also cover any area of regular table zone that might cause vac loss if needed

i use commercial type ball bearing hinges for allignments and then just fold them back before cutting
(i have only forgotten about the hinges 1 time in thousands of parts
trashed a bit and the part but actually cut the hinge in to)

also watch out when zeroing or returning home, etc. to make sure your safe z clears the hinges. probably is a safer way than the steel hinges but it is simple and works for me

i cut 2'x4' and 2'x3' down to about 6"x8" with this setup regularly
also circles and ovals sometimes

[kra]

probably obvious but i also start cut from side and move into part keeping z the same throughout cut and park spindle out of the way for loading next part always keeping z the same (in my case 0 ) then cut another one
if you pause or anything during cut and the bit raises to safe z it trashes the part