Total Newbie Needs Help

[DocRock]

Aloha All,

I'm new to VCP and CNCing for that matter. I have a large table we are creating out of a 2.5in thick walnut table blank we glued up. It's basically a very large oval and we are attempting two seemingly easy but I'm learning $1700 worth of wasted wood later it's not as easy as it looks.

First we need a profile cut that will create the initial shape of the oval 106"x44." so first question is how do we accomplish this when the bit is only sticking out about 2.25" (totally willing to buy new end mills if needed) I almost killed a brand new machine doing this wrong already.
'
Second we need a gradual slope inward starting about .25" up from bottom of material and sloping inward until we reach the top of material about 2.25" creating a angular sweep if you will. see pic.

Please any advise on doing this from proper bits to how to do tool paths to feed and speeds will help. Already drained a lot of time and $$$ doing this the incorrect way. Please excuse any mistakes in this post again absolutely green here.



file to take a look if you dare can be found here: https://d.pr/cqFC

Thanks in advance for any help.

Mahalo,
Doc

[Rcnewcomb]

I have a couple of suggestions:
1."learning $1700 worth of wasted wood later it's not as easy as it looks." Use pink or blue foam insulation sheets for practice. It is much more forgiving and cheaper while you learn.
2. "2.5in thick walnut table blank", but your thickness in your CRV file is only 2.25. If you plan on cutting this out on the CNC then you should change that to 2.5"
3. "how do we accomplish this when the bit is only sticking out about 2.25" " You need a bit with at least a 2.5" cutting edge length (not just the length of the bit sticking out of the collet)
4. You should also use a Zero plane (Model/Add Zero Plane) to eliminate some rough edges

[FixitMike]

I would suggest having a bit custom made with the length and angle required.
https://www.google.com/search?q=custom+ ... 8&oe=utf-8

[4DThinker]

The edge bevel can be done using the Moulding toolpath. Once that is done if you pocket down the waste outside of the oval some your 2.25" end mill should be able to finish off profile cutting out the oval. In this example I used a .5" ball end bit to do the bevel, and .5" end mill to both rough cut for the bevel, pocket down the perimeter, and do the final profile cutout. Assumes a vacuum table or your own choice for holding down the board.

4D

[dwilli9013]

The long DOC endmills you would need are available here.
Please do post final pics of your project sounds amazing.

https://www.bqtool.com/extra-length-bal ... mills.html

[Kayvon]

4. You should also use a Zero plane (Model/Add Zero Plane) to eliminate some rough edges

Is that an option in VCarve? I know it is in Aspire.

[Adrian]

4. You should also use a Zero plane (Model/Add Zero Plane) to eliminate some rough edges

Is that an option in VCarve? I know it is in Aspire.

Yes it is.

[martin54]

4. You should also use a Zero plane (Model/Add Zero Plane) to eliminate some rough edges

Is that an option in VCarve? I know it is in Aspire.

As Adrian has said yes it is, if you look at the drop down menus at the top of the screen it comes under the modelling tab

That would only be from version 8 of the software though when they introduced all the modeling features to Vcarve

[DocRock]

Thanks for all the great ideas. I attempted to do what 4D said and got almost the results except I'm losing some of my .25" thickness at the very ends.

I also tried the zero plane thingy but didn't see any visual feedback other than fast calculating line at the bottom of the UI, is this normal?

Thanks again,
Doc

[Rcnewcomb]

The Zero plane will help eliminate the "chatter" you would get at the edge of your model if you didn't have it.

[tomgardiner]

You are experiencing a geometry phenomena. When you reduce an ellipse by a ratio you do not maintain parallel lines between original and reduced ellipse. To overcome this, offset inwards by the required amount. Fit curves to that smaller ellipse to reduce the number of nodes.

[4DThinker]

Thanks for all the great ideas. I attempted to do what 4D said and got almost the results except I'm losing some of my .25" thickness at the very ends.

I also tried the zero plane thingy but didn't see any visual feedback other than fast calculating line at the bottom of the UI, is this normal?

Thanks again,
Doc

If you used the moulding tool path then you should have used an inner offset line that was the exact same distance from the outer ellipse all the way around as your drive rail. to end up with an edge that was the same thickness all around. Done right the outer edge would not be touched while cutting the bevel, and a profile pass using the outer ellipse would give you a clean edge. I tried to upload my .CRV file but it was too large even zipped. I drew a side view of the bevel to use as the profile for the Moulding tool path, and used a boundary offset of just 1/2 the diameter of the ball nose bit I used.

4D

[adze_cnc]

First we need a profile cut that will create the initial shape of the oval 106"x44." so first question is how do we accomplish this when the bit is only sticking out about 2.25" (totally willing to buy new end mills if needed) I almost killed a brand new machine doing this wrong already.

Cutting deeper than the length that your bit projects is tricky but not impossible. In the attached image there is a deep relief pocket around the outside such that when the bit is at its deepest the collet nut and part of the router body are below the material top but safe as they have somewhere to go.

Steven

[DocRock]

Aloha 4D,

Would you mind sending me the .crv via email, dropbox, droplr please. My email is docrock at gmail dot com. Still struggling with doing a equidistant offset. Pretty sure it's easier than i'm making it .

Mahalo,
Doc

If you used the moulding tool path then you should have used an inner offset line that was the exact same distance from the outer ellipse all the way around as your drive rail. to end up with an edge that was the same thickness all around. Done right the outer edge would not be touched while cutting the bevel, and a profile pass using the outer ellipse would give you a clean edge. I tried to upload my .CRV file but it was too large even zipped. I drew a side view of the bevel to use as the profile for the Moulding tool path, and used a boundary offset of just 1/2 the diameter of the ball nose bit I used.

4D

[4DThinker]

Aloha 4D,

Would you mind sending me the .crv via email, dropbox, droplr please. My email is docrock at gmail dot com. Still struggling with doing a equidistant offset. Pretty sure it's easier than i'm making it .

Mahalo,
Doc

Check your email.
4D