Sharp cornered mdf doors

[GlenP]

Hey all, anyone out there with a PRS standard cutting mdf doors with a vbit to create sharp outside corners? I have having alot of trouble getting the cut clean as right now the cutter will take too much out of the corner and leave a awful profile which will require tons of sanding to clean up.

[Gary Campbell]

Glen...
Are you talking about sharp outside corners on interior carving, or on the outside profile?

Here is a set of vanity doors we do for a local designer that has a recessed beaded wainscot design. A V bit is used on the outside corner of the "panel" to get the required square corner. Also required was that the beads line up between the door and draw fronts above.
Heres the set:


45638.jpg

Closup of the corner:


45639.jpg
Gary

[GlenP]

Hey Gary, I am talking about the sharp corners on the interior panel corners. I am doing some sample doors and using aspire. For some testing I just made a simple rectangle and did a profile cut to cut on the inside with sharp corners turned on. Every test cut the cutter makes a corner that looks like the cutter diameter is incorrect but I have changed the cutter diameter values both up and down with no success in corner. I never have much luck posting pics here from our camera but I can send you the pics of the cut to your email if required. I have done lots of mdf doors with the rounded corners but want to do the sharp panel corners and have also been asked about doors just as you have created.

[Gary Campbell]

Glen...
To make the border,like you I drew and selected a rectangle, selected inside profile, 90 degree V bit, .25 depth and sharp inside and outside corners using VCPro5. It sounds as tho you did exactly the same, so I am a little stumped.

You can send the pics if you want, and I will look them over and post so that those wiser then I may be able to get you in the right direction.
Gary

[GlenP]

Thanks Gary. I will send them in the morning to you. I am hoping someone with a PRS Standard will chime in as that is the machine I am using. I do not use vacuum for hold down just screws to the spoilboard. I was using a 120 degree 2" diameter cutter with even a low .125" max cut depth to rule out too much down pressure and the material rising while the corner is being cut. I have tested close to both x rails to check for x motor backlash and the same cut. Heck I tested in the middle of the bed and same cut. When you look at the cut it just looks like the cutter is going too high (deep)into the corners when going up to create the sharp corner. I was wondering if IU reduce the cornering values to see if it is just backlash on the standard motors. ????? Thanks in advance for any help and ideas.

[myxpykalix]

GlenP go to www.xat.com and download
"jpegoptimizer". It will allow you to keep your pictures at 640x480 but shrink the kilobyte size to under 50k so you can post your pictures here.

45657.jpg

Gary- on your wainscoting to my eyes it looks like the beading is inset (i know its all one piece) and is lower than the surface of the rails and stiles or is it all the same height?
Nice looking though.

[GlenP]

Hey guys, here is the post on the vectric site to see a pic.
http://www.vectric.com/forum/viewtop...f=3&t=6415

[Gary Campbell]

Jack...
Yes the interior panel was pocketed out .125 before the beads were cut into it. This is a 4 bit job

1/2" downspiral pocket out panel .125 (from surface)
90 Vbit IS profile .25 deep around border
1/8 pointed roundover .21 deep (includes .125 from pocket)
3/8 compression to cut profile climb/conv

Heres the Setup in VCPro:

45669.jpg

And the preview:

45670.jpg
Gary

[tkovacs]

Glen,
I have a PRS standard and have never seen anything like what you are posting on the vectric site.
Looks to me like when the corner is cut the z axis is not moving up fast enough to keep pace with the xy motion.

Terry

[zeykr]

I think as someone else has mentioned, that the actual bit angle or size is different from the settings in the tool database. It's not at all unusual for v bit to be off several degrees or for endmills to be a little under or over the stated size.